Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Load Detection And Monitoring Apparatus
The present invention relates to a fluid powered apparatus
that has application for clamping, punching, welding and
other functions that are necessary in the manufacture and
assembly of machines and vehicles such as automobiles.
More particularly, the invention is related to a dual
action fluid powered apparatus designed to implement a
rapid movement in approaching a workpiece until contact is
effected. The movement of the apparatus upon contact with
the workpiece is then transformed to a slow, more powerful
working mode. Specifically, this invention is a device for
detecting and monitoring the engagement force between the
apparatus and a workpiece, and this application is divided
from application 2,025,641, filed September 18, 1990.
The prior art reveals a wide variety of fluid powered
devices that employ a plurality of cylinder and piston
combinations to control the speed and force of the device
as an element thereof advances toward a workpiece.
In general, most of the prior art devices utilize a tandem
arrangement for the various pistons that are all contained
within a single cylindrical housing.
By way of example, the present invention differs from the
oleopneumatic jack that is shown and described in U.S.
Patent No. 3,426,530 entitled "Oleopneumatic Jack with
Staged Structure" issued February 11, 1969, to Alexander
Georgelin. The jack has a cylindrical tubular body
structure with end caps attached thereto. A first piston
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is positioned at one end within the cylindrical body. The
piston has attached thereto an elongated hollow plunger
that is adapted to move with the piston. A floating piston
is positioned so that it slides freely along the previously
mentioned hollow plunger. A third piston is positioned
near the other end of the cylindrical body. The third
piston has coupled thereto, as an integral part, a thrust
member that protrudes from the other end of the cylindrical
body. The third piston contains a hollow central chamber
into which extends a portion of a thrust member. Air
pressure is applied to one end of the floating piston thus
causing it to urge oil against the third piston which in
turn causes the thrust member attached to the third piston
to extend from the cylindrical body. After the initial
rapid advancement of the third piston and the thrust
member, air pressure is introduced behind the first piston.
As the first piston moves axially along the interior of the
cylindrical body, its attached hollow plunger enters the
oil filled hollow central chamber of the third piston thus
~0 causing it to move slowly while exerting a large force.
In U.S. Patent No. 4,099,436 entitled "Apparatus for
Piercing Sheet Material" issued July ll, 1978, to Donald
Beneteau, there is described a force intensifier that
employs an oil reservoir that is external of a cylindrical
structure that contains a pair of pistons in axial
alignment. The oil in the reservoir is forced into the
cylinder by pressurized air that is in direct contact with
the oil. The oil that is introduced into the cylinder
moves one of the pistons, causing a tool carrying plunger
to advance toward a workpiece. In order to intensify the
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force delivered by the tool carrying plunger, air is
introduced behind the other piston, causing it to move an
attached plunger into a constricted cavity where the oil
pressure is greatly increased, thereby exerting an even
greater force on the tool carrying plunger.
An additional load producing cylinder is shown in Figure 3
of U.S. Patent No. 4,395,027 entitled "Pressure
Intensifying Device" issued July 26, 1983, to Robert
Nordmeyer. Figure 3 of the above referenced patent depicts
a cross-sectional view of a pressure intensifying device
that has an essentially cylindrical configuration. There
is a first piston and plunger combination that moves in the
direction towards a second piston plunger combination. The
first piston moves under the influence of air pressure and
returns to its original position by the biasing action of a
compression spring. The second piston is essentially
hollow and is filled with oil that supplies the force that
causes the second piston and plunger to move linearly.
After the second piston has accomplished its initial
movement, the first piston plunger is advanced into the oil
filled chamber of the second piston. The force on the
second piston is thus intensified. The cylinder contains
an internally positioned oil reservoir through which the
first piston plunger passes. The just mentioned device
utilizes, in tandem, pistons that move in the same
direction during the initial or advancement movement. One
of the inherent drawbacks of the just described device is
its overall length. Then, too, the spring that is biased
against the first piston subtracts from the overall load
that is applied by air pressure.
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The apparatus of this invention does not have an air-oil
interface since the oil is self-contained completely within
the confinement of the apparatus. In addition, the
invention has a plunger unit that is separable from the
load enhancement plunger.
The apparatus with which this invention is associated does
not utilize springs to aid in the movement of the pistons.
Also, the invention is not arranged in a continuous linear
array as is the device described in U.S. Patent 4,395,027.
The present invention relates to a load intensifier
apparatus for use in any application where a linear force
of considerable magnitude is required such as in metal
shaping, punching, clamping, and welding. The invention
provides a load measuring device for such an oleopneumatic
load intensifier apparatus which causes a rapid advance of
a tool carrying piston rod followed by slow advance of the
piston rod at an increased load. The oleopneumatic
apparatus has a master cylinder and an actuating cylinder
that can assume different positions with respect to the
master cylinder while maintaining fluid communication
therewith. An enclosed hydraulic system is shared by the
master and actuating cylinders. Pneumatic pressure
actuates a piston within the master cylinder that causes a
rapid advancement of a hydraulic fed piston within the
actuating cylinder, causing a piston rod and a tool
associated therewith to contact a workpiece. The load
measuring device monitors the load associated with the
pneumatic pressure applied to the piston and associated
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piston rod, located in the master cylinder, and the
resultant force applied to the hydraulic fed piston located
within the actuating cylinder, to precisely determine the
load delivered to the workpiece.
The apparatus of the invention includes a two part housing
wherein the second portion of the housing can be arranged
at any attitude with respect to the first portion of the
housing. The first portion of the housing contains an
enclosed oil reservoir that is in communication with the
second housing. The first portion of the housing contains
a floating piston that moves along the piston rod of an
intensifier piston. The second portion of the housing
contains a piston and a piston rod that extends from the
housing. In the first housing, air pressure is introduced
to one side of the floating piston causing a volume of oil
located on the other side of the floating piston to move
into the second portion of the housing where its pressure
causes the piston within the second portion of the housing
to undergo rapid movement to advance the attached piston
rod toward a workpiece. After the rapid movement of the
piston in the second portion of the housing has occurred,
the pressure intensifier piston within the first portion of
the housing is moved under the influence of air pressure.
The end of the piston rod of the intensifier piston then
enters a constricted oil passageway causing a slow but
intense movement of the piston in the second portion of the
housing. The further movement of the piston in the second
portion of the housing causes its piston rod to
additionally bias itself against the workpiece.
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In one aspect, the invention provides an apparatus for
intensifying a force that is applied to a tool to move said
tool into and out of engagement with a workpiece. The
apparatus comprises a master cylinder having a first
manifold, a second manifold adjacent the first manifold,
and a third manifold spaced relative those first and second
manifolds. The first, second and third manifolds each have
at least one aperture therein, and are axially aligned and
in spaced apart relationship to one another. Means form a
first cavity between the first and second manifolds, and
means form a second cavity between the second and third
manifolds. An intensifier piston is positioned in the
first cavity, the intensifier piston defining first and
second chambers in that first cavity. A reservoir piston
is positioned in the second cavity, the reservoir piston
defining third and fourth chambers in that second cavity.
That reservoir piston has a central bore therein, and an
intensifier rod is coupled to the intensifier piston, the
intensifier rod passing through an aperture in the second
manifold and the central bore of the reservoir piston. An
actuating cylinder is positioned in juxtaposed relationship
with respect to the master cylinder. Means form a third
cavity within the actuating cylinder; a piston is
positioned in the third cavity of the actuating cylinder,
that piston defining fifth and sixth chambers on each side
of the piston. The third chamber adjacent the reservoir
piston and the sixth chamber adjacent that piston each
contain hydraulic fluid. Passage means can place the third
and sixth chambers in fluid communication with each other,
that passage means communicating with the second and third
manifold at one end and having an opposite end attached to
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the actuating cylinder. A piston rod is attached to the
piston, the piston rod having a free end cantilevered from
the actuating cylinder. Means are provided for introducing
pressurized pneumatic fluid to the fourth chamber adjacent
the reservoir piston, to cause the reservoir piston to
force hydraulic fluid from the reservoir piston third
chamber into the actuating cylinder sixth chamber that is
adjacent to that piston, such that the piston and attached
piston rod advance at a first predetermined rate toward a
workpiece. Means can introduce pressurized pneumatic fluid
to the first chamber adjacent the intensifier piston, to
cause the intensifier piston to move and further to move
the coupled intensifier rod into one end of the passage
means and act on the hydraulic fluid in the sixth chamber
such that the pressure of the hydraulic fluid is
intensified for introduction to the actuating cylinder
sixth chamber that is adjacent that piston to cause the
piston rod attached to the piston to advance at a second
predetermined rate toward the workpiece.
By another aspect the invention provides an apparatus for
intensifying a force that is applied to a tool to move said
tool into and out of engagement with a workpiece. The
apparatus includes a master cylinder having a first
manifold, a second manifold adjacent the first manifold,
and a third manifold spaced relative to those first and
second manifolds. The first, second and third manifolds
each have at least one aperture therein, and are axially
aligned and in spaced apart relationship to one another.
Means form a first cavity between the first and second
manifolds, and means form a second cavity between the
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second and third manifolds. An intensifier piston is
positioned in the first cavity, that intensifier piston
defining first and second chambers in the first cavity. ~A
reservoir piston is positioned in the second cavity, the
reservoir piston defining third and fourth chambers in that
second cavity, and the reservoir piston has a central bore
therein. An intensifier rod is coupled to the intensifier
piston, and passes through the at least one aperture in the
second manifold and the central bore of the reservoir
piston. An actuating cylinder is positioned in spaced
relationship with respect to the master cylinder. Means
form a third cavity within the actuating cylinder, and a
piston is positioned in that third cavity of the actuating
cylinder. That piston defines fifth and sixth chambers on
each side of the piston. The fourth chamber adjacent the
reservoir piston and the sixth chamber adjacent the piston
each contain hydraulic fluid. Passage means can place the
fourth and sixth ehambers in fluid communication with each
other; the passage means having one end juxtaposed the
master cylinder and an opposite end attached to the
aetuating eylinder. A piston rod is attached to the
piston, the piston rod having a free end cantilevered from
the actuating eylinder. Means are loeated in the seeond
manifold for introducing pressurized fluid to the third
chamber adjacent the reservoir piston, to cause the
reservoir piston to force hydraulic fluid from the
reservoir piston fourth chamber into the actuating cylinder
sixth chamber that is adjacent to that piston, such that
the piston and the attached piston rod advance at a first
predetermined rate toward a workpiece. The means for
introducing pressurized fluid to the third chamber
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comprises at least one port passage complementary with the
one of the at least one apertures of the second manifold,
to provide ingress of pneumatic fluid to pressurize the
third chamber adjacent the reservoir piston, and means for
introducing pressurized pneumatic fluid to the first
chamber adjacent the intensifier piston to cause the
intensifier piston to move and further to move the coupled
intensifier rod into the at least one aperture of the third
manifold to act on the hydraulic fluid therein such that it
is intensified for introduction to the actuating cylinder
sixth chamber, to cause the piston rod attached to the
piston to advance at a second predetermined rate toward the
workpiece.
In accordance with this invention a load detection device,
for monitoring the engagement force between a tool and a
workpiece, comprises means having a free end for
transmitting a force, the force being transmitted at the
free end. A load cell has one face juxtaposed that free
end of the means for transmitting a force, for monitoring
the force of that force-transmitting means. Biasing means
is mounted between the free end and that one face of the
load cell, the biasing means providing a biasing force to
urge the load cell monitoring the force away from that free
end. A piston rod adapter is provided, having a blind bore
at one end and an open end opposite that one end; the
opposite end being slidably mounted to the free end of the
means for transmitting a force. The biasing means and the
load cell are mounted in the blind bore of the piston rod
adapter, and are interposed between the free end and the
bottom of the blind bore. Means for limiting the movement
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of the means for transmitting a force relative to the
piston rod adapter are included; the limiting means being
mounted to the means for transmitting a force such that the
force transmitted at the free end of the means for
transmitting a force is counteracted by the biasing means,
and the net effect of the force is monitored by the load
cell to determine the engagement force between the tool and
the workpiece.
The invention also provides a load detection device for
monitoring a tool when engaging and disengaging a
workpiece. The load detection device comprises a piston
rod having a free end, the piston rod transmitting a force
at the free end, and having a diametral aperture located
adjacent the free end. A load cell is located adjacent the
free end of the piston rod. A spring is interposed between
the free end and the load cell, the spring biasing the load
cell away from the free end, and transmitting the force
between the piston rod and the load cell. A piston rod
adapter is slidably telescoped over the free end of the
piston rod, and encloses the load cell and the spring. The
piston rod adapter has a pair of diametrally-opposed
longitudinal slots disposed thereon, and a radially-aligned
bore for egress of an electrical connection to the load
cell. A pin simultaneously engages the diametral aperture
of the piston rod and the pair of diametrally-opposed
longitudinal slots of the piston rod adapter; the pin
retaining the piston rod adapter of the piston rod. The
pin is capable of traversing the pair of diametrally-
opposed longitudinal slots for providing axial movement ofthe piston rod adapter in relation to the piston rod.
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The invention will now be described in more detail, by way of
example only, with reference to the accompanying drawings in
which:-
Figure 1 is a perspective view that shows a preferred
embodiment of the force intensifier of the present invention;
Figure 2 is a top view of the preferred embodiment of Figurel;
Figure 3 is a cross-sectional view taken along section line
3-3 of Figure 2 showing the cylinders and pistons and their
interrelationship to one another;
Figure 4, with Figure 1, is a part sectional view of the
preferred embodiment of Figure 1 as mounted to a mounting
bracket;
Figure 5, with Figure 1, is a cross-sectional view showing
the intensifier cap seal arrangement depicted in circle 5 of
Figure 3;
Figure 6, with Figure 1, is a cross-sectional view showing
the positions of the 0-ring and backup ring arrangement of
the actuating cylinder detailed in circle 6 of Figure 3;
Figure 7, with Figure 1, shows an alternative embodiment with
the actuating cylinder in fluidic communication with the
master cylinder by an external fluid connection to the end
cap;
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Figure 8A is a cross-sectional view that shows the position
of the pistons and piston rods in the fully retracted
position;
Figure 8B is a cross-sectional view that shows the position
of the pistons and piston rods after pressure has been
applied to the reservoir piston;
Figure 8C is a cross-sectional view similar to that shown in
Figures 8A and 8B except that intensification has occurred;
Figure 8D is a legend to the fluid pressures indicated in
Figures 8A through 8C and Figures 13A and 13D;
Figure 9 is a part sectional view of an embodiment that
employs a load cell near the end of the working piston rod;
Figure 10 shows an alternate mounting arrangement with the
actuating cylinder directly mounted to the master cylinder
auxiliary port;
Figure 11 is a schematic view that shows the valving system
utilized with the present apparatus;
Figure 12 is a cross-sectional view of a second embodiment of
the invention showing the cylinders and pistons and their
interrelationship to one another;
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Figure 13A is a cross-sectional view of the second embodi-
ment that shows the position of the pistons and piston rods
in the fully retracted position;
Figure 13B is a cross-sectional view similar to that shown
in Figure 13A showing the position of the pistons and piston
rods after pressure has been applied to the retract piston;
Figure 13C is a cross-sectional view similar to that shown
o in Figure 13A and 13B showing the position of the pistons
and piston rods after pressure has been applied to the
reservoir piston; and
Figure 13D is a cross-sectional view similar to that shown
in Figures 13A, 13B and 13C except that intensification has
occurred; and
Figure 14 depicts yet a further embodiment of the invention
wherein the actuating cylinder can be arranged to have any
attitude with respect to the master cylinder.
Referring now to the drawings and more particularly to
Figure 1, there is illustrated in perspective one configura-
tion of the present load intensification apparatus. The
overall apparatus is identified by the numeral 10. The
overall apparatus 10 has two distinct subassemblies or
housings which shall hereinafter be identified as the master
cylinder 12 and the actuating cylinder 14. The master
cylinder 12 is essentially a hollow structure with a first
or front manifold 16, a second or center manifold 18, and an
end cap 20 that are in spaced apart, axially aligned
relationship to one another. A cylindrically shaped thin-
walled front sleeve 22 is positioned between the front
manifold 16 and the center manifold 18. A similar cylindri-
cally shaped rear sleeve 24 is positioned between the center
manifold 18 and the end cap 20. The master cylinder 12 is
held together by studs 26 that pass through each one of the
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manifolds 16 and 18 and the end cap 20. The studs 26 are
threaded on each end and tension thereon is maintained by
threaded nuts 28.
The actuating cylinder 14 is cylindrical throughout its
internal and external configuration. As shown in the
preferred embodiment of Figure 1, the actuating cylinder 14
is directly mounted to the end cap 20 with threaded
fasteners 40. While the actuating cylinder 14 is shown in a
lo parallel attitude with respect to the master cylinder 12, it
is readily understood that the orientation and positioning
of the actuating cylinder 14 can be altered to fit any
particular application by providing an auxiliary port 42 to
the end cap 20. A fluidic connection 38 can then be used
between the master cylinder 12 and the actuating cylinder
14, as shown as an alternative embodiment in Figure 7.
Further, if desired, the actuating cylinder 14 may be
mounted directly to the end cap's 20 auxiliary port 42 for a
90~ direct mounting configuration as shown in Figure 10.
Additionally, it is readily understood that this embodiment
allows a single master cylinder 12 to control any desired
number of actuating cylinders 14 in series or in parallel
connection. Accordingly, the master cylinder 12 should be
proportionally sized for the particular application. Figure
3 is a cross-sectional view of the overall apparatus 10 that
is depicted in Figure 1. Figure 3 shows the pistons and
their interrelationship to one another in an at rest
condition. The front sleeve 22 may, if desired, have the
same overall dimensions as the rear sleeve 24. The front
and rear sleeves 22 and 24 are preferably manufactured from
steel. The leading end 48 of the front sleeve 22 fits over
a machined boss 50 on the front manifold 16. Even though
close tolerances are maintained between the inside diameter
of the front sleeve 22 and the outside diameter of the boss
50, it is desirable to utilize an O-ring 52 for sealing
purposes. The trailing end 54 of the front sleeve 22 fits
over a machined boss 56 on the center manifold 18. An
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O-ring 58 is utilized between the machined boss 56 and the
interface with the front sleeve 22 to ensure a fluid tight
joint. The leading end 60 of the rear sleeve 24 fits over a
machined boss 62 on the center manifold 18. An 0-ring 64 is
positioned so that it effects a fluid tight seal between the
inside surface of the rear sleeve 24 and the machined boss
62. The trailing end 66 of the rear sleeve 24 fits over a
machined boss 68 on a third or an annular manifold member
72. An O-ring 70 is used to ensure a fluid tight seal
lo between the inside surface of the rear sleeve 24 and the
machined boss 68. The end cap 20 is attached to the
trailing end of the annular manifold member 72. A first 0-
ring 74 ensures a fluid tight seal between the perimeter of
the annular manifold member 72 and the end cap 20. A second
O-ring 76 is utilized to maintain a fluid tight seal between
a reduced portion of the annular manifold member 72 and the
end cap 20. The annular manifold member 72 has a bore 78
that contains a groove 80 therein for an elastomeric seal 82
retained by a retainer cap 81, as best illustrated in Figure
5. The purpose of the reduced diameter bore 78 will be
discussed in more detail below.
An intensifier piston 104 is positioned within a bore 106 in
the front sleeve 22. The intensifier piston 104 is sealed
against the bore 106 by means of an O-ring 108. An
intensifier piston rod 110 is centrally attached to the
intensifier piston 104 by a threaded fastener 118. The
intensifier piston rod 110 passes through a bore 120 that is
located in the center manifold 18. A groove 122 within the
bore 120 carries an 0-ring 124 provided as a seal between
the center manifold 18 and the intensifier piston rod 110.
An annular-shaped floating reservoir piston 132 is
positioned over the intensifier piston rod 110. A portion
of an inner surface 126 of the floating reservoir piston 132
is elongated and tapered to closely mate with a frustoconi-
cally shaped portion 128 of the annular manifold member 72.
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The reservoir piston 132 iS positioned within a bore 134
within the rear sleeve 24. The floating reservoir piston
132 iS sealed against the surface of the bore 134 by means
of a leading end O-ring 136 and a trailing end O-ring 138,
located in grooves 140 and 142, respectively, in the
floating reservoir piston 132. The floating reservoir
piston 132 iS also sealed against the intensifier piston rod
110 along which it slides by O-rings 144 and 146 which seal
the floating reservoir piston 132 against the intensifier
o piston rod 110 on opposite sides of a relief passage 148
within the floating reservoir piston 132. The relief
passage 148 places the area between the leading and trailing
end O-rings 136 and 138 on the perimeter of the floating
reservoir piston 132 and the area between the O-rings 144
and 146 adjacent the intensifier piston rod 110 in fluid
communication, thus preventing the build up of residual
pressure between the leading and trailing end O-rings on the
floating reservoir piston 132. The arrangement of the
floating reservoir piston 132 on the intensifier piston rod
20 110 within the rear sleeve creates two fluid chambers 152
and 154 within the area of the rear sleeve 24. The fluid
chamber 152 lies between the annular manifold member 72 and
the internal surface 126 of the floating reservoir piston
132. The fluid chamber 154 lies between the center manifold
18 and a recess in the leading face of the floating
reservoir piston 132.
The front manifold 16 contains a fluid chamber 156 and a
threaded bore 160. An additional fluid chamber 162 lies
30 between the intensifier piston 104 and the center manifold
18. The center manifold 18 contains a first bore or port 86
that is in communication with the chamber 154. A second
bore or port 164 iS in communication with the additional
fluid chamber 162. The end cap 20 contains a bore 168 that
is in communication with the chamber 152 through the reduced
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diameter bore 78 in the annular manifold member 72. In
addition, the end cap 20 has a supply port 90 which is also
in fluidic communication with the chamber 152 via a supply
passage 92 in the annular manifold member 72. A reservoir
94, positioned in any convenient location, is fluidically
connected to the supply port so for purposes of supplying the
chamber 152 with hydraulic fluid. A one-way check valve 96
is positioned between the reservoir 94 and the supply port 90
to allow fluid to be supplied to the chamber 152 and also to
prevent backflow from the chamber 152 to the reservoir 94.
The actuating cylinder 14 has an external cylindrical
configuration over its axial extent. The rear portion of the
actuating cylinder 14 has a bore 174 that is threaded (not
shown) for communication with the bore 168 of the end cap 20.
The interior of the actuating cylinder 14 is formed by an
axial bore 176 that extends over approximately the rear one
half of the actuating cylinder 14. The remaining or forward
one half of the interior of the actuating cylinder 14 is
formed by an axially extending bore 178 that is of greater
diameter than the axial bore 176 of the rear half of the
actuating cylinder. A radially extending shoulder 180 forms
the intersection between the bores 176 and 178. A sleeve 182
is positioned within the bore 178 of the actuating cylinder
14. The shoulder 180 acts as a stop for the sleeve 182 thus
defining its axial position within the actuating cylinder 14.
A rear piston 184 is positioned within the bore 176. The
rear piston 184 has a first 0-ring seal and backup rings 185
positioned within a groove 187, and a second 0-ring seal 186
positioned within a groove 188 located in the cylindrical
exterior surface of the rear piston 184 as more clearly shown
in Figure 6. A piston rod 46 has one end thereof attached to
the rear piston 184. The piston rod 46 has a reduced
diameter end 192 with a threaded portion (not shown) that
extends through an axially aligned bore 194 in the rear
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piston 184. The rear piston 184 is attached to the piston
rod 46 by means of a threaded nut 196 that engages the
threaded portion threads (not shown) on the end of the
reduced diameter end 192 of the piston rod 46. The piston
rod 46 extends from the rear piston 184 through the entire
axial extent to the right, as viewed in Figure 3, where it
exits the actuating cylinder 14 as an unencumbered
cantilevered end 198.
Returning once again to the actuating cylinder 14, a forward
piston 200 is press fit onto the piston rod 46. The forward
piston 200 is located generally toward the mid-portion of the
axial extent of the piston rod 46. The forward piston 200
has a peripheral groove 202 that contains an 0-ring 204. The
sleeve 182 accommodates the forward piston 200 within a bore
206 of the sleeve 182. The 0-ring 204 seats against the
surface of the bore 206. The sleeve 182 contains a second
bore 212 that permits the piston rod 46 to pass therethrough,
forming a chamber 210 between the forward piston 200 and the
shoulder formed between the bore 206 and the second bore 212.
The second bore 212 contains a groove 214 in which an 0-ring
216 is positioned for providing a seal between the sleeve 182
and the piston rod 46. The sleeve 182 contains a groove 218
positioned in its external surface so that an 0-ring 220 can
be placed therein to effect a seal between the sleeve 182 and
the bore 178 of the actuating cylinder 14.
The section of the piston rod 46 located to the right of the
forward piston 200, as viewed in Figure 3, has a diameter
that is less than the bore 206 of the sleeve 182, thus
forming a chamber 222. The chamber 222 is in communication
with a central bore 226 through the rear portion of the
piston rod 46 by way of a radial passage in the piston rod
46. In a similar manner, the rear piston 184 has a radial
bore 228 extending between the 0-ring seals 185 and 186 that
is in communication with the central bore 226. A chamber
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231, which is positioned to the right of the rear piston 184,
is in communication with a passage 232 in the sleeve 182. A
chamber 236, located to the left of the rear piston 184 as
viewed in Figure 3, iS in communication with the fluid
chamber 152 of the master cylinder 12 via the bore 174 of the
actuating cylinder 14, the passage 168 in the end cap 20, and
the bore 78 in the annular manifold member 72.
A retaining bushing 44 iS mounted to the forward portion of
the actuating cylinder 14 and has an external part
cylindrical section 240 that fits into the bore 178 to
establish the chamber 222. The retaining bushing 44 iS
immobilized by means of a retaining ring 242 that coacts with
a groove 244 in the wall of the bore 178 in the actuating
cylinder 14 and with a groove 246 that is milled in the
external surface of the external part cylindrical section
240.
As can be better seen in Figure 1, the piston rod 46 contains
a milled planar area 248 on one side and a similar milled
planar area 250 on the other side thereof which is optional.
The purpose of the milled planar areas 248 and 250 iS to
provide orientation to the piston rod 46 SO that it will not
rotate and cause misalignment with a nonsymmetrical tool that
may be affixed to the cantilevered end 198 of the piston rod
46.
Figure 4 is a part sectional view of an embodiment that
employs a trunnion 254 as an integral part of the actuating
cylinder 14. Figure 4 shows the trunnion 254 engaged with
mounting slots 256 within a mounting bracket 258. This
arrangement allows the actuating cylinder 14 to be pivoted to
the preferred attitude for a particular application.
Figure 9 is a part sectional view of an embodiment that
employs a load cell device within the piston rod 46 of the
actuating cylinder 14. Figure 9 shows the sleeve 182, the
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piston rod 46 and the retaining bushing 44 similar to like
components shown in Figure 3. The piston rod 46 has a
reduced diameter cylindrical section 30. The reduced
diameter cylindrical section 30 telescopes within a piston
rod adapter 32. The piston rod adapter 32 has an external
cylindrical surface that fits within a bore 34 in the
retaining bushing 44. The piston rod adapter 32 has an
internal bore 36 into which the telescoping end of the
piston rod 46 fits. A load cell 35 is positioned within the
lo bore 36 and a compression spring 37 is aligned within the
bore 36 between the end of the piston rod 46 and the load
cell 35. In order to retain the piston rod adapter 32 on
the end of the piston rod 46, a pin 33 is installed in a
bore 31 that is diametrically aligned with respect to the
piston rod 46. The pin 33 protrudes beyond the external
surface of the reduced diameter cylindrical section 30. The
ends of the pin 33 fit into slots 29 that are milled into
the piston rod adapter 32. In this manner, the piston rod
adapter 32 has a limited degree of axial movement with
respect to the piston rod 46. The piston rod adapter 32 has
a radially aligned bore 39 that permits electrical lead
wires 41 of the load cell 35 to exit the interior of the
piston rod adapter 32. During operation of the overall
apparatus the piston rod 46 causes the compression spring 37
to exert a force on the load cell 35. After the load has
been released from the load cell, the compression spring 37
will cause the piston rod adapter 32 to move axially subject
to the constraints of the pin 33 and the slots 29.
During the assembly of the overall apparatus 10, great care
must be taken to preserve the integrity of the seals,
particularly the 0-rings which are subject to the nicks
caused by assembly. The master cylinder is assembled by
installing the appropriate seals on the reservoir piston 132
and the intensifier piston 104. The intensifier piston 104
is affixed to the end of the intensifier piston rod 110 by
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CA 02238139 1998-07-13
the threaded fastener 118. The intensifier piston rod 110
is then inserted through the bore 120 in the center manifold
18. The reservoir piston 132 is then slid over the free end
of the intensifier piston rod 110. The front and rear
sleeves 22 and 24 are then installed over the respective
bosses 56 and 62 on the center manifold 18. The front
manifold 16 and the annular manifold member 72 are then
positioned so that their respective bosses 50 and 68 slide
within the ends of the front and rear sleeves 22 and 24.
lo The end cap 20 is then positioned against the annular
manifold member 72, aligning the bore 168 with the reduced
diameter bore 78 and the supply port 90 with the supply
passage 92. The four studs 26 are then installed in the
holes (not shown) within the front and center manifolds 16
and 18 and the end cap 20. The studs 26 are then tensioned
by the installation of the nuts 28.
During the assembly of the actuating cylinder 14, the
forward piston 200 is press fit onto the piston rod 46 as
seen in Figure 3, the fit being an interference fit. The
sleeve 182 is then positioned over the left end (as viewed
in Figure 3) of the piston rod 46. Next, the rear piston
184 is affixed to the end of the piston rod 46 by the nut
196. The rear piston 184, the piston rod 46 and the sleeve
182 are installed within the bores 176 and 178 of the
actuating cylinder 14. The retaining bushing 44 is then
slid over the cantilevered or free end 198 of the piston rod
46. The retaining bushing 44 is then moved into locking
arrangement with the retaining ring 242. The actuating
cylinder 14 is then mounted to the end cap 20 with the
threaded fasteners 40.
Figure 8A is a cross-sectional view that shows the position
of the pistons and piston rods when the overall apparatus 10
is in the fully retracted position. At the commencement of
a cycle of the overall apparatus 10, the intensifier piston
10~
- 21 -
CA 02238139 1998-07-13
is held to the extreme right end of the chamber 162 by high
air pressure, as shown, through the bore 120 and its external
port. Consequently, the end of the intensifier piston rod
110 is retracted to a position outside of the bore 78
permitting the fluid chamber 152 to communicate with the bore
78. The reservoir piston 132 is to the extreme right end of
travel against the center manifold 18. In the actuating
cylinder 14 portion of the overall apparatus 10, the rear
piston 184 is positioned toward the extreme left toward the
end cap 20 defining the greatest extent of the chamber 231,
therefore, the extreme right free end of the piston rod 46 is
almost entirely retracted within the confinement of the
actuating cylinder 14. The forward piston 200, acting as an
integral part of the piston rod 46, is positioned against the
shoulder defined by the bores 212 and 206.
Figure 8B is a cross-sectional view that shows the position
of the pistons and piston rods after the overall apparatus 10
has been actuated to begin a work cycle. Air pressure is
introduced to the fluid chamber 154 through the first bore 86
causing the reservoir piston 132 to move toward the left.
The oil to the left of the reservoir piston 132 begins to
exit the fluid chamber 152 and, being prevented from
returning to the reservoir 94 by the check valve 96, travels
via the reduced diameter bore 78 and the bore 168 into the
chamber 236. The increase in volume of oil in the chamber
236 causes the rear piston 184 to move rapidly to the right.
As the rear piston moves toward the right, air is exhausted
from the chamber 231 through the passage 232. Since the
forward piston 200 acts as a part of the piston rod 46, the
forward piston 200 also moves toward the right thus causing
an ingress of atmospheric air into the chamber 210 and an
egress of atmospheric air from the chamber 222. After the
initial introduction of air pressure to the fluid chamber 154
at the right of the reservoir piston 132 there is a rapid
deployment of the piston rod 46 to the right where its travel
CA 02238139 1998-07-13
is halted by an interception with, for example, a workpiece
47. It has been determined through experimentation that
performance characteristics may be diminished if the forward
piston 200 is driven toward the right by introducing air
pressure into the chamber 210 during the commencement of the
cycle illustrated in Figure 8B. The cause for this loss in
performance is believed to be the result of a ~sucking
action" created when the forward piston 200, as a result of
air pressure introduced into the chamber 210, begins to
lo travel before or travels at a faster rate than the reservoir
piston 132, thereby forming a partial vacuum in the chamber
236. This in turn provides an additional force that compels
the reservoir piston 132 to travel to the left faster than
intended by the action of the air pressure in the fluid
chamber 154. Figure 8C is a cross-sectional view similar to
that shown in Figures 8A and 8B that shows the final stage of
the work cycle of the overall apparatus 10. Since rapid
deployment of the piston rod 46 has brought a tool (not
shown) carried by it into contact with the workpiece 47, the
load must be increased beyond the capability of the air
pressure normally found at an industrial site. Consequently,
air pressure is introduced into the chamber 156 which is
positioned to the right of the intensifier piston 104. As
the intensifier piston 104 moves to the left, the tip of the
intensifier piston rod 110 enters the bore 78 in the annular
manifold member 72, causing the oil trapped before it to act
as a closed loop system between the intensifier piston rod
110, the bore 78, and the chamber 236. The continued travel
of the intensifier piston rod 110 into the bore 78 acts on
the oil in the chamber 236 urging the rear piston 184 to the
right, delivering a greatly increased or intensified force to
the piston rod 46. The actual movement of the piston rod 46
has been exaggerated in Figure 8C for purposes of
illustrating the movement thereof. The increased movement of
the forward piston 200 to the right will exhaust additional
atmospheric air from the chamber 222 and cause an influx of
additional atmospheric air into the chamber 210. Thus, there
will be a combined hydraulic
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CA 02238139 1998-07-13
intensifying force introduced to the piston rod 46.
On the return stroke, both the intensifier piston 104 and
the rear piston 184 are driven back to their original
positions by introducing high pressure air into their
respective chambers 162 and 231 through the bore 164 and the
passage 232. The return stroke of the rear piston 184 acts
to return the reservoir piston 132 to its original position
to the right end of the fluid chamber 152 against the center
0 manifold. As an added feature to ensure adequate
performance of the apparatus 10, there is provided a
proximity sensor 252 for sensing the position of the
reservoir piston 132 in relation to the extreme left end of
the fluid chamber 152. As shown in Figure 3, the proximity
sensor 252 is located adjacent the extreme left end of the
fluid chamber 152 and can be instrumented through any
conventional means to relay a warning signal when the
reservoir piston 132 is approaching the end of its stroke
capability within the fluid chamber 152. This condition
would arise if, for example, the hydraulic fluid within the
fluid chamber 152 has dropped to an unacceptable level. By
way of a warning signal, an operator of the apparatus 10 is
put on notice that replenishment of the hydraulic system is
necessary. Figure 11 is a schematic fluid diagram according
to the present invention and the controls that achieve the
fluid motion. For purposes of the present invention the
fluids have been described as air and oil. Figure 11 shows
a simplified layout of the pistons and piston rods. Since
the oil within the overall apparatus 10 is self-contained,
the oil has been shown for clarity as section lines. In
order to operate the overall apparatus through its entire
work cycle, only external air pressure need be applied. For
purposes of explanation, it is assumed the overall apparatus
10 is coupled to an air supply 272. Air under pressure is
supplied to a three-way valve mechanism 274 which is a
solenoid actuated spring return device. The air under
pressure exits the air supply through a line 276 and travels
- 24 -
CA 02238139 1998-07-13
through the three-way valve mechanism 274 to a line 278 and
to the chamber 231. The air supply 272 also supplies air
under pressure to a line 304 which is connected to the two-
way valve mechanism 288 which supplies air under pressure to
the chamber 162. The air pressure supplied to the chamber
231 causes the rear piston 184 to move to the left as viewed
in Figure 8A forcing the oil from the chamber 236 into the
fluid chamber 152 and urging the floating reservoir piston
132 to the right. As the floating reservoir piston 132 moves
0 to the right, air is exhausted from the fluid chamber 154
through a line 282 to the valve mechanism 274 which permits
the expelled air to enter a line 284 and travel to an exhaust
port 286 which may, if desired, be a device such as a muffler
to attenuate the noise level of the exhausting air. The air
pressure delivered via a line 280 to the chamber 162 causes
the intensifier piston 104 to remain to the right, ensuring
that the tip of the intensifier piston rod 110 does not
impede the flow of oil into the fluid chamber 152. The
chamber 156 is connected to the two-way valve mechanism 288
by a line 290. In the unenergized position, the two-way
valve mechanism 288 permits pressurized air in the chamber
156 to exhaust through the line 290 to a line 292 and pass to
the exhaust port 286. At the start of the cycle, a solenoid
294 on the normally open three-way valve mechanism 274 is
energized by the movement of a workpiece into a work station
or by other means that connect to an electrical source to the
solenoid. The energizing of the solenoid 294 connects the
air supply line 276 to the line 282 pressurizing the fluid
chamber 154 through the port in the manifold 18 through the
first bore 86 which causes the floating reservoir piston 132
to move to the left, forcing oil from the fluid chamber 152
into the chamber 236. Oil entering the chamber 236 causes
the rear piston 184 to move rapidly to the right, hence the
piston rod 46 moves to the right along with the forward
piston 200. The energizing of the solenoid 294 on the three-
way valve mechanism 274 also causes the air supply line 278
to the chamber 231 to become connected to the exhaust line
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- - -
CA 02238139 1998-07-13
284. As the forward piston 200 moves to the right, air is
exhausted from the chamber 222 through a line 295 and air
from the exhaust port 286 is drawn through a line 296 to the
chamber 210. After the piston rod 46 has made its rapid
advance toward and against a workpiece such as is identified
by numeral 298, the pressure, or an electrical sensing switch
such as 300, energizes a solenoid 302 on the normally closed
two-way valve mechanism 288 causing the line 304 to be
switched from its connection to line 280 to be reversed and
lo be connected to the line 290 and at the same time the line
280 is switched to be connected to the exhaust line 292. The
air pressure delivered by the line 290 to the chamber 156
causes the intensifier piston 104 to move to the left thus
permitting the tip of the intensifier piston rod 110 to enter
the bore 78 and apply an intensified pressure on the oil in
the chamber 236. The increased force supplied to the rear
piston 184 is transferred to the piston rod 46 and to the
workpiece 298. At the command of an operator or by auto-
matic timing, the solenoids 294 and 302 are deenergized,
permitting springs 306 and 308 to return the valve mechanisms
274 and 288 to their original starting positions. It is to
be noted that by utilizing air to hold the intensifier piston
positively in place while the floating reservoir piston is
sub~ected to air pressure avoids the need for using springs
and results in a more positive control of the intensifier
piston. It is also to be noted that appropriate bleed
passages are provided, as is customary in the art, between
cooperating seals to prevent the buildup of residual
pressures due to blowby.
By way of illustration, the intensifier piston rod 110 has a
diameter of 0.5 inches and the intensifier and rear pistons
104 and 184 each have a diameter of 1.75 inches. The in-
crease in the pressure delivered to the rear piston 184
varies as the square of the diameter, 1.75 squared divided by
0.5 squared yields a pressure increase of 12.25. Thus, if
typical shop air at 80 p.s.i. is delivered to the intensifier
- 26 -
CA 02238139 1998-07-13
piston, there will be 980 p.s.i. delivered to the rear
piston 184.
In a second embodiment of the present invention, Figure 12
illustrates a load intensification apparatus identified by
numeral 410. The load intensification apparatus 410 of the
second embodiment is distinguished from the load intensifi-
cation apparatus 10 of the first embodiment by the provision
of an intermediate retract position capability. As will be
lo readily seen, the intermediate retract position facilitates
multiple weld operations by reducing the cycle time between
successive welds which do not require the full clearance
provided by the full retract position of the overall
apparatus 10.
In a manner similar to the first embodiment, Figure 12 shows
the overall apparatus 410 of the second embodiment having a
master cylinder 412 and an actuating cylinder 414 which
together constitute two distinct subassemblies or housings
of the overall apparatus 410. The overall apparatus 410 of
the second embodiment is constructed nearly identically to
the overall apparatus 10 of the first embodiment except for
specific modifications to the master cylinder 412 which will
be delineated below.
Similar to the first embodiment, the master cylinder 412 of
the second embodiment has a front manifold 416, a center
manifold 418, and an annular manifold member 472 which are
in spaced-apart, axially-aligned relationship to one
another. Cylindrically-shaped front and rear sleeves 422
and 424 are positioned between the front and center manifold
416 and 418, and the center manifold and annular manifold
member 418 and 472, respectively. The front and rear
sleeves 422 and 424 form a front bore 506 and a rear bore
534, respectively. Within the rear bore 534 there is
provided a retaining ring 538 within an internal groove 540
- 27 -
CA 02238l39 l998-07-l3
which is positioned approximately midway between the annular
manifold member 472 and the center manifold 418. The
retaining ring 538 iS of sufficient strength to act as a
piston stop in a manner to be described later.
The annular manifold member 472 has an elongated annular
portion 473 with an outer cylindrical surface 528 extending
towards the center manifold 418. The interior surface of
the elongated annular portion 473 provides a reduced dia-
o meter bore 478. An end cap 420 in part is mounted to the
annular manifold member 472 on a side opposite the elongated
annular portion 473. The end cap 420 has a bore 568 that is
in communication with the reduced diameter bore 478 of the
annular manifold member 472.
As with the first embodiment, the second embodiment has an
intensifier piston 504 which is attached to an intensifier
piston rod 510 and is positioned within the front bore 506.
The intensifier piston 504 divides the front bore 506 into a
20 first chamber 556 adjacent the front manifold 416, and a
second chamber S62 adjacent the center manifold 418. The
first chamber 556 iS in fluidic communication with a port
560 in the front manifold 416. The second chamber 562 iS in
fluidic communication with a port 564 within the center
manifold 418. The intensifier piston rod 510 passes through
a bore 520 located in the center manifold 418 and extends
short of the reduced diameter bore 478 of the annular
manifold member 472.
Similar to the first embodiment, a floating reservoir piston
532 of the second embodiment is positioned over the intensi-
fier piston rod 510 within the rear bore 534. The floating
reservoir piston 532 divides the rear bore 534 into a third
chamber 554 adjacent the center manifold 418, and a fourth
chamber 552 adjacent the annular manifold member 472. The
third chamber 554 iS in fluidic communication with a port
- 28 -
CA 02238139 1998-07-13
436 in the center manifold 418. The fourth chamber 552 is
in fluidic communication with the reduced diameter bore 478
of the annular manifold member 472 and the bore 568 of the
end cap 420. The end cap 420 also is provided with a supply
port 490 which is in fluidic communication with the rear
bore 534 through a supply passage 482 in the annular
manifold member 472.
In contrast to the first embodiment, the floating reservoir
o piston 532 is truncated and does not mate with the cylindri-
cal surface 528 of the annular manifold member 472.
Instead, the floating reservoir piston 532 is retained
within the rear bore 534 between the center manifold 418 and
the retaining ring 538.
In addition, in the second embodiment a retract piston 536
which is positioned over the outer cylindrical surface 528
of the annular manifold member 472 is provided. The retract
piston 536 defines a retract chamber 553 within the rear
bore 534 between the annular manifold member 472 and the
retract piston 536. The retract piston 536 operates between
the annular manifold member 472 and the retaining ring 538
such that the retract piston 536 always remains piloted upon
the outer cylindrical surface 528 of the annular manifold
member 472. Further, the retract piston 536 is constructed
such that it cannot interrupt the fluidic path between the
fourth chamber 552 and the reduced diameter bore 478. The
retract chamber 553 is in communication with the supply port
490 via the supply passage 482 for purposes of actuating the
retract piston 536.
Similar to the first embodiment, a proximity sensor 652 is
provided for sensing the position of the floating reservoir
piston 532 in relation to the retaining ring 538. The
proximity sensor 652 serves to warn an operator that the
quantity of hydraulic fluid within the fourth chamber 552 is
low and needs replenishing. The hydraulic fluid is
- 29 -
CA 02238139 1998-07-13
introduced into the fourth ehamber 552 through a fill port
542 positioned in proximity to the retaining ring 538.
The actuating cylinder 414 is constructed identically to the
actuating cylinder 14 of the first embodiment. As shown, the
S actuating cylinder 414 is mounted to the end eap 420, but as
noted with the first embodiment, the actuating cylinder 414
can be fluidically connected to the end cap 420 with a
suitable fluidic connection. The rear portion of the
actuating cylinder 414 has a bore 576 that is in fluidic
communication with the bore 568 of the end cap 420. A rear
piston 584 is positioned within the bore 576. The rear
piston 584 is attached to a piston rod 446 which extends from
the rear piston 584 through the entire axial extent to the
right, where it exits the actuating cylinder 414 as an
lS unencumbered cantilevered end 598.
The rear piston 584 divides the bore 576 into a fifth and
sixth chamber 631 and 636, respectively. The sixth chamber
636 is in eommunication with the fourth chamber 552 of the
master cylinder 412 via the passage 568 in the end cap 420
and the reduced diameter bore 478 in the annular manifold
member 472.
Operation of the seeond embodiment is nearly identieal to the
first embodiment exeept for the ability of the foree
intensifieation apparatus 410 to reaeh an intermediate
retraet position from either the fully retraeted or fully
extended position. Figure 13A is a eross-seetional view that
shows the position of the pistons and piston rods when the
overall apparatus 410 is in the fully retracted position. At
the commencement of a cycle, the intensifier piston 504 is
held to the extreme right end of the front bore 506 by high
pressure air in the second chamber 562, as shown.
Consequently, the end of the intensifier piston rod 510 is
retracted to a position outside of the reduced diameter bore
- 30 -
CA 02238139 1998-07-13
478 permitting the fourth chamber 552 to communicate with
the reduced diameter bore 478. The floating reservoir
piston 532 is to the extreme right end of its travel against
the center manifold 418. The retract piston 536 is to the
extreme left end of its travel against the annular manifold
member 472.
In the actuating cylinder 414, the rear piston 584 is held
by high pressure air to the extreme left toward the end cap
lo 420 defining the greatest extent of the fifth chamber 631.
Therefore, the extreme right free end of the piston rod 446
is almost entirely retracted within the confinement of the
actuating cylinder 414.
Figure 13B is a cross-sectional view that shows the position
of the pistons and piston rods after the overall apparatus
10 has been actuated to the intermediate retract position at
the start of a work cycle. Air pressure is introduced into
the retract chamber 553 through the supply port 490, causing
the retract piston 536 to move toward the center manifold
418 until it abuts against the retaining ring 538. A volume
of oil corresponding to the volume displaced by the retract
piston 536 exits the fourth chamber 552 and travels via the
reduced diameter bore 478 and the bore 568 to the sixth
chamber 636. The increase in volume of oil in the sixth
chamber 636 causes the rear piston 584 to move rapidly to
the right. Consequently, there is a rapid deployment of the
piston rod 446 to the right where its travel is arrested a
predetermined distance from a workpiece 447, serving as an
intermediate retract position for the overall apparatus 410.
The predetermined distance traveled by the piston rod 446 is
determined directly by the volume of oil displaced by the
retract piston 536.
Figure 13C is a cross-sectional view that shows the position
of the pistons and piston rods after the overall apparatus
410 has been actuated to engage the workpiece 447. Figure
- 31 -
CA 02238139 1998-07-13
13C corresponds to Figure 8B of the first embodiment, and
the operation of the overall apparatus 410 corresponds
accordingly. Air pressure is introduced to the third cham-
ber 554 causing the floating reservoir piston 532 to move to
the left toward the retract piston 536. An additional
volume of oil corresponding to the volume displaced by the
floating reservoir piston 532 exits the fourth chamber 552
and travels via the reduced diameter bore 478 and the bore
568 into the sixth chamber 636, further causing the rear
o piston 584 to mover rapidly to the right. The piston rod
446 consequently moves rapidly to the right where its travel
is halted by its interception with the workpiece 447.
Figure 13D is a cross-sectional view corresponding to Figure
8C of the first embodiment, showing the final stage of the
work cycle of the overall apparatus 410. For achieving
force intensification at the piston rod 446, air pressure is
introduced into the first chamber 556 to the right of the
intensifier piston 504. As the intensifier piston 504 moves
to the left, the tip of the intensifier piston rod 510
enters the reduced diameter bore 478 in the annular manifold
member 472, causing the oil trapped before it to act as a
closed system between the intensifier rod 510, the bore
reduced diameter 478, the bore 568 and the sixth chamber
636. The continued travel of the intensifier piston rod 510
into the reduced diameter bore 478 acts on the oil in the
sixth chamber 636 urging the rear piston 584 to the right,
delivering a greatly increased or intensified force to the
piston rod 446.
According to the second embodiment of the present invention,
the overall apparatus 410 does not automatically return to
the fully retracted position shown in Figure 13A, but
returns to the intermediate retract position shown in 13B
for purposes of facilitating rapid successive weld opera-
tions. To return the overall apparatus 410 to the inter-
mediate retract position from the intensified position, air
- 32 -
CA 02238139 1998-07-13
pressure is released from the first chamber 556 and reintro-
duced in the second chamber 562 to drive the intensifier
piston 504 back to its original position. Consequently, the
intensifier piston rod 510 is withdrawn from the reduced
diameter bore 478, simultaneously reducing the pressure
against the rear piston 584 in the sixth chamber 636. The
floating reservoir piston 532 is driven back to its original
position by the partial return stroke of the rear piston 584
in cooperation with the releasing of the high pressure air
lo from the third chamber 554 which had originally moved and
held the floating reservoir piston 532 in its actuated
position. The rear piston 584 and, therefore, the piston
rod 446, is retracted to the intermediate retract position
upon the floating reservoir piston 532 being returned to its
original position. The rear piston 584 and the piston rod
446 retract no further because of the volume of oil yet
displaced by the retract piston 536.
At the end of a multiple weld operation, the operation of
the overall apparatus 410 is again similar to the overall
apparatus 10 of the first embodiment. From the intermediate
retract position, air pressure is re-introduced into the
fifth chamber 631, driving the rear piston 584 back to its
original position. Upon release of the high pressure air in
the retract chamber 553 which had originally moved and held
the retract piston 536 in its actuated position, the retract
piston 536 is returned to its original position adjacent the
annular manifold 472 by the return stroke of rear piston
584.
From the above, it can be appreciated that rapid successive
weld operations can be accomplished more quickly by elimin-
ating the first embodiment's requirement for a complete
retraction of the piston rod 446 between weld operations.
The overall apparatus 410 under the second embodiment can
rapidly perform a successive number of weld operations by
CA 02238139 1998-07-13
first extending to the intermediate retract position (Figure
13B), further extending to the weld position (Figure 13C),
intensifying during the weld operation (Figure 13D),
partially retracting to the intermediate retract position
(Figure 13B) which is designed to sufficiently clear the
workpiece 447, and then return to the weld position (Figure
13D) for an additional intensification and weld operation.
When the desired series of weld operations is completed, the
overall apparatus can then be cycled directly from the
lo intermediate retract position (Figure 13B) to the full
retract position (Figure 13A) for purposes of providing
maximum clearance with the workpiece 447.
A fluid control system for the second embodiment of the
present invention would be analogous to the schematic fluid
diagram of the first embodiment illustrated in Figure 11.
Those with ordinary skill in the art can readily recognize
the minor modifications necessary to accommodate the opera-
tional requirements of the retract piston 536. By example,
a solenoid-operated valve can be employed to operate the
retract piston 536 between its "stowed" position when the
piston rod 446 is fully retracted, and its "deployed"
position when the piston rod 446 is at the intermediate
retract, weld and intensified positions. In addition, the
three-way valve mechanism 274 of the first embodiment can be
modified to provide a valve position in which both lines 282
and 278 are exhausted to the exhaust port 286 when the
overall apparatus is in the intermediate retract position.
Figure 14 depicts yet a further embodiment of the invention
wherein the actuating cylinder can be arranged to add any
attitude with respect to the master cylinder in an arrange-
ment as provided which permits viewing of the self-contained
hydraulic system to assure replenishing thereof, as
necessary. The embodiment illustrated differs from the
preferred embodiment in that a viewing tube 730 for viewing
- 34 -
CA 02238139 1998-07-13
the hydraulic fluid contained within the master cylinder 712
spans the distance between the center manifold 718 and the
rear manifold 720. A nipple 732 is positioned in axial
alignment with the viewing tube 730 and a quick disconnect
fitting 734 is coupled to the cantilevered end of the nipple
732. The quick disconnect fitting 734 provides for easy
access to the hydraulic system should the addition of
hydraulic fluid become necessary.
A compression fitting 90~ elbow 736 is attached to the
lo rear manifold 720. The elbow 736 is in turn coupled with an
elastomeric tube 738 that is made of urethane or other
suitable material that can withstand contact with hydraulic
oil and reasonable pressures generated thereby. The
elastomeric tube 738 is coupled to a straight compression
fitting 740.
An actuating cylinder 714 is essentially cylindrical
throughout its internal and external configuration and at the
back end has a tapped hole to accept the compression fitting
740. The front end of the actuating cylinder is supported by
a mounting plate 742. The mounting plate 742 is cantilevered
in a downward direction from its rigid support on the front
manifold 716. While the actuating cylinder 714 is shown in a
parallel attitude with respect to the master cylinder 712, it
is readily understandable that the flexible nature of the
elastomeric tube 738, as well as its selectable, varying
length, permits orientation or positioning of the actuating
cylinder 714 to assume any location with respect to the
master cylinder 712. A retaining bushing 744 is attached to
the front end of the actuating cylinder 714. The retaining
bushing 744 permits the end of a piston rod 746 to protrude
therefrom. By way of example, a tool 747, such as an
electrode for welding purposes, can be affixed to the
cantilevered end of the piston rod 746.
CA 02238139 1998-07-13
Figure 14 shows the pistons and their interrelationship
to one another. The front 722 and rear 724 sleeves as in the
preferred embodiments are assembled to their respective
manifolds similar to the preferred embodiment. An end cap
772 is attached to the trailing end of the rear manifold 720.
The end cap 772 has a threaded section that engages similar
threads in an axially aligned bore 774 in the rear manifold
720. An o-ring 776 is utilized to maintain a fluid tight
seal between the end cap 772 and the rear manifold 720. The
end cap 772 has a reduced diameter bore 778 that contains a
groove 780 for the elastomeric seal 782. The purpose of the
reduced diameter bore 778 will be discussed in more detail
below.
The center manifold 718 has a 90~ elbow fitting
threadedly engaged in an upper threaded bore 786. The elbow
fitting 784 has its non-threaded end 788 directed toward the
left or toward the rear manifold 720. A tee fitting 790 has
its stem end 792 threadedly engaged within a threaded lower
bore 794 in the rear manifold 720. The lower bore 794 is
located on the top of the rear manifold 720. The top of the
tee fitting 790 is aligned so that its axis is parallel with
the longitudinal axis of the master cylinder 712. The
viewing tube 730 is aligned between the tee fitting 790 and
the end 788 of the elbow fitting 784. 0-ring seals 796 and
798 effect seals at the leading and trailing ends 800 and 802
of the viewing tube 730 with the respective elbow fitting 784
and tee fitting 790. The viewing tube 730 can be fabricated
from tempered glass tubing or high strength plastic material.
The nipple 732 is threadedly attached to the end of the tee
fitting 790 and the quick disconnect fitting 734 is attached
to the nipple 732. Thus, the quick disconnect fitting 734,
the nipple 732, and the viewing tube 730 are in axial
alignment with one another.
- 36 -
CA 02238139 1998-07-13
As in the preferred embodiment, an intensifier piston
804 is positioned within a bore 806 in the front sleeve 722.
The intensifier piston 804 is sealed against the bore 806 by
means of an 0-ring 808. An intensifier piston rod 810 is
centrally attached to the intensifier piston 804. A reduced
diameter end 812 of the intensifier piston rod 810 is
positioned within a bore 814 in the intensifier piston 804.
The intensifier piston 804 is immobilized by the attachment
of a threaded fastener nut 818 to a threaded portion of the
reduced diameter end 812. The intensifier piston rod 810
passes through a bore 820 that is located in the center
manifold 718. A groove 822 within the bore 820 carries an 0-
ring 824 provided for a seal between the center manifold 718
and the intensifier piston rod 810. The intensifier piston
rod 810 also passes through a bore 826 that is located within
the rear manifold 720. A seal is maintained between the rear
manifold 720 and the intensifier piston rod 810 by means of
an 0-ring 828 that is positioned within a groove 830 in the
wall of the bore 826.
A floating reservoir piston 832 is trained over the
intensifier piston rod 810. The floating reservoir piston
832 is positioned within a bore 834 in the rear sleeve 724.
The floating reservoir piston 832 is sealed against the
surface of the bore 834 by means of an 0-ring 836 and wiper
seals 838 and 840 that are positioned on each side of the 0-
ring 836. The 0-ring 836 and accompanying wiper seals 838
and 840 are positioned within a groove 842 that is located in
a peripheral surface of the floating reservoir piston 832.
The floating reservoir piston 832 is also sealed against the
intensifier piston rod 810 along which it slides. A glide or
wiper ring 844 and an adjacent 0-ring 846 are positioned in
grooves 848 and 850, respectively. The positioning of the
floating reservoir piston 832 on the intensifier piston rod
810 creates two fluid chambers 852 and 854 within the area of
the rear sleeve 724. The first fluid chamber 852 lies
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CA 02238139 1998-07-13
between the rear manifold 720 and the floating reservoir
piston 832. The second fluid chamber 854 lies between the
center manifold and the floating reservoir piston 832.
The front manifold 716 contains a fluid chamber 856 and
an elbow fitting 858 that is threaded into a threaded bore
860 of the front manifold. The bore 860 is in communication
with the fluid chamber 856 and the elbow fitting 858. An
additional fluid chamber 862 lies between the intensifier
piston 804 and the center manifold 718. The center manifold
718 contains the upper bore 786 that is in communication with
the second chamber 854 and the elbow fitting 784. A lower
bore 864 is in communication with the additional fluid
chamber 862 and an elbow 866 that is threaded into the bottom
of the center manifold 718. The rear manifold 720 contains a
bore 868 that is in communication with the first fluid
chamber 852 and the interior of an elbow fitting 870 that is
anchored in the rear manifold 720.
The actuating cylinder 714, like in the preferred
embodiment, has an external cylindrical configuration over
its axial extent. The rear portion of the actuating cylinder
714 has a section 872 of reduced external diameter. The end
of the section 872 contains a bore 874 that is threaded (not
shown) for coupling with the compression fitting 740. The
interior of the actuating cylinder 714 is formed by an axial
bore 876 that extends over approximately the rear half of the
actuating cylinder 714. The remaining or forward half of the
actuating cylinder 714 is formed by an axially extending bore
878 that is of greater diameter than the axial bore 876 of
the rear half of the actuating cylinder. A radially
extending shoulder 880 forms the intersection between the
bores 876 and 878. A sleeve 882 is positioned primarily
within the bore 878 of the actuating cylinder 714. A portion
of the sleeve 882 is of reduced external diameter so that it
fits within the bore 876. The reduced external diameter
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CA 02238139 1998-07-13
portion of the sleeve 882 creates a reentrant notch that
coacts with the shoulder 880 of the actuating cylinder 714.
The shoulder 880 acts as a stop for the sleeve 882, defining
its axial position within the actuating cylinder 714.
A rear piston 884 is positioned within the bore 876.
The rear piston 884 has on O-ring seal 886 positioned within
a groove 888 located in the cylindrical exterior surface of
the rear piston 884. The piston rod 746 has one end thereof
attached to the rear piston 884. The piston rod 746 has a
reduced diameter end portion 892 that extends through an
axially aligned bore 894 in the rear piston 884. The rear
piston 884 is attached to the piston rod 746 by means of a
threaded nut 896 that engages threads (not shown) on the end
of the reduced diameter end portion 892 of the piston rod
746. The piston rod 746 extends from the rear piston 884
through the entire axial extent to the right, as viewed in
Figure 2, where it exits as an unencumbered cantilevered end
898.
Returning once again to the sleeve 882, a forward piston
900 is machined into the piston rod 746 as an integral part
thereof. The forward piston 900 is located generally toward
the mid-portion of the axial extent of the piston rod 746.
The forward piston 900 has a peripheral groove 902 that
contains an O-ring 904. The sleeve 882 accommodates the
forward piston 900 within a bore 906. The O-ring seal 904
seats against the surface of the bore 906. The sleeve 882
contains a second bore 908 that can be seen in Figure 2 to
the left of the forward piston 900. The second bore 908
forms a chamber 910 between the internal surface of the
second bore 908 and the external surface of the piston rod
746. The sleeve 882 contains a third bore 912 that permits
the piston rod 746 to pass therethrough. The bore 912
contains a groove 914 in which an O-ring 916 is positioned
for providing a seal between the sleeve 882 and the piston
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CA 02238139 1998-07-13
rod 746. The sleeve 882 contains a groove 918 positioned in
its external surface so that an O-ring 920 can be placed
therein to effect a seal between the sleeve 882 and the bore
876 of the actuating cylinder 714.
The section of the piston rod 746 located to the right
of the forward piston 900, as viewed in Figure 2, has a
diameter that is less than the bore 906 of the sleeve 882,
forming a chamber 922. The chamber 922 has a bore 924 that
is in communication with an elbow fitting 926. In a similar
manner, the chamber 910 has a bore 928 that is in
communication with an elbow fitting 930. A chamber 931,
which is positioned to the right of the rear piston 884, has
a bore 932 that is in communication with an elbow fitting
934, and a chamber 936, located to the left of the rear
piston 884, is in communication with the second chamber 854
of the master cylinder 712 via the bore 874, the elastomeric
tube 738, the elbow 736, a bore 938 in the end cap 772, the
reduced diameter bore 778, the threaded lower bore 794, and
the viewing tube 730 and its included elbow and tee fittings.
The retaining bushing 744 is supported by the mounting
plate 742. The mounting plate 742 is anchored to the front
manifold 716 by studs 726 and nuts 728. The retaining
bushing 744 has an external part cylindrical section 940 that
fits into the axially extending bore 878. The retaining
bushing 744 is immobilized by means of a training ring 942
that coacts with a groove 944 in the wall of the axially
extending bore 878 in the actuating cylinder 714 with a
groove 946 that is milled in the external surface of the part
cylindrical section 940.
The operation of the embodiment shown in Figure 14 is
similar to that of the preferred embodiment. Figure 14
represents the apparatus in its fully retracted position.
The cycle is actuated by introducing air pressure to the
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CA 02238139 1998-07-13
chamber 852 causing the floating reservoir piston 832 to move
to the right. The oil to the right of the floating reservoir
piston 832 begins to exit the second chamber 854 and travel
via the viewing tube 730 and the elastomeric tube 738 into
the chamber 936. The increase in volume of oil in the
chamber 936 causes the rear piston 884 to move rapidly to the
right. As the rear piston moves towards the right, air is
exhausted from the chamber 931. Since the forward piston 900
is a part of the piston rod 746, the forward piston 900 also
moves to the right, causing an ingress of air into the
chamber 910 and an egress of air from the chamber 922. After
the initial introduction of air pressure to the chamber 854
at the left of the floating reservoir piston 832, there is a
rapid deployment of the piston rod 746 to the right where its
travel is halted by interception with a workpiece. The
intensification cycle is now ready to begin and since it is
clear to one skilled in the art that the cycle is identical
to that described in the preferred embodiment, the cycle will
not be repeated herein. Once intensification has been
accomplished, the device returns back to a rest position by
relieving the air pressure in the chamber 856 and applying
air pressure in the additional fluid chamber 862 while
simultaneously applying air pressure in the chamber 931 to
return the hydraulic fluid in the chamber 936 to the chamber
854 and relieving the air pressure in the chamber 852 to
allow the floating reservoir piston 832 to return to its
initial starting position.
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