Note: Descriptions are shown in the official language in which they were submitted.
29020 8
ADJUSTABLE STROKE CONNECTION
1. Field of the invention.
The present invention relates to mechanical stamping and
drawing presses, and, more particularly, to apparatus for an
adjustable stroke connection for adjusting the stroke length of
the press slide.
2. Description of the related art.
In mechanical presses, it is often desirable to adjust or
change the stroke length of a reciprocating member, for example
the slide, to which stamping tooling is installed. In some prior
art toothed adjustment systems, there is a tendency for the
system parts to wear after a certain period of operation time.
It would be desirable to provide an apparatus or system which may
be utilized to quickly, easily, and accurately adjust the stroke
length of the slide or other parts.
The present invention provides a dual eccentric adjustable
stroke connection system for use in changing the stroke length of
the slide or other member of a mechanical press.
An eccentric on a rotatable crankshaft is supplied with an
eccentric bushing disposed thereon. A press connection member,
such as a connecting rod or link, is attached about the eccentric
bushing. During normal operation, there is relative movement
between the eccentric bushing and connecting member or arm to
thereby cause reciprocation of the press slide. During stroke
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adjustment, pressurized oil is communicated between the eccentric
bushing and crankshaft eccentric, thereby relieving the press fit
or interference fit therebetween, and causing the eccentric
bushing to expand and form a temporary press fit connection with
the connecting arm. At this time, crankshaft may be rotated,
along with its eccentric, to thereby change the position of the
eccentric within the eccentric bushing. This causes a change of
stroke length. The oil pressure is then relieved thereby causing
the eccentric bushing to contract and again form a press fit or
interference fit with the crankshaft eccentric and release the
temporary press fit connection between the outside of the
eccentric bushing and connection member or arm. After such high
oil pressure has been reduced, normal press operations may
proceed.
The invention comprises, in one form thereof, a mechanical
press having, a press connection member, an eccentric bushing
disposed within the press connection member, and a second
eccentric member disposed within the eccentric bushing, the
second eccentric member releasably connectable with the eccentric
bushing. A rotatable crankshaft is connected to the second
eccentric member. The invention includes means for connecting
the eccentric bushing with the press connection member to prevent
rotation therebetween and permitting rotation of the second
eccentric member within the eccentric bushing whereby rotation of
the crankshaft, when the means is activated, then causes a press
stroke adjustment. The invention also includes at least one high
coefficient of friction seal, disposed between the second
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eccentric member and the eccentric bushing, where the high
friction seal prevents rotation of the eccentric bushing relative
to the second eccentric member prior to creation of the temporary
press fit connection.
, The invention comprises, in another form thereof, a fluid
pressure means for connecting the eccentric bushing with the
press connection member to prevent rotation therebetween and
permitting rotation of the second eccentric member within the
eccentric bushing. The fluid pressure means includes fluid
passageways through the crankshaft in communication with a fluid
pressure intensifier means for increasing fluid pressure through
the crankshaft passageways. In one form of the invention the
intensifier may include a movable piston to increase the fluid
pressure within the crankshaft passageways.
An advantage of the present invention is that a mechanical
press may now include a simple and compact stroke adjustment
connection operated by fluid pressure. Prior stroke adjustment
connections utilized keys and/or gearing between the crankshaft
and various eccentrics. The present invention utilizes a
connection that is simple in design and vastly reduces the number
of parts necessary for a stroke adjustment mechanism.
Another advantage of the present invention is that a
significant reduction in costs is obtained along with increasing
the functionality of the press with a simple stroke adjustment
connection. Additionally, maintenance costs for adjustment and
replacement parts, as compared to prior adjustable stroke
connections, are reduced.
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Another advantage of the present invention is that of a
fluid intensifier which achieves a high ratio of fluid
intensification while disposed within the press crank shaft. The
new and novel fluid intensifier of the present invention is
simple in construction and operation, thereby requiring simple
rotary sealing arrangements.
The above-mentioned and other features and advantages
of this invention, and the manner of attaining them, will become
more apparent and the invention will be better understood by
reference to the following description of embodiments of the
invention taken in conjunction with the accompanying drawings,
wherein:
Figure 1 is a schematic, perspective view in partial cut
away of a portion of the crankshaft and slide connection;
Figures 2A and 2B are two cross-sectional views of the
crankshaft and eccentric bushing, at maximum and minimum stroke
positions respectively, wherein the connection is shown in
elevational view, and wherein the oil conduits for lubrication
and crankshaft adjustment are not shown;
Figure 3 is an enlarged view of the crankshaft and eccentric
bushing of Figure 2A;
Figures 4A and 4B are schematic, axial cross-sectional views
of the invention at separate times of operation, namely during
normal stamping operations and during stroke length/eccentric
adjustment, respectively;
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Figure 5 is an axial, cross-sectional view of an alternate
embodiment of the invention showing an additional connection
bushing between the eccentric bushing and the connection, and
with an oil conduit for crankshaft adjustment shown;
Figure 6A is an axial, cross-sectional view of a first
eccentric bushing. Figures 6B and 6C are an axial cross-
sectional view and a side view, respectively, of another
eccentric bushing. Figure 6D is an axial, cross-sectional view
of still another eccentric bushing;
Figure 7 is an axial, cross-sectional view of an embodiment
of the present invention in which a suitable method of supplying
high pressure oil to the crankshaft without a high pressure
rotary union is shown;
Figure 8 is a schematic, partial cross-sectional view of a
second seal configuration for sealing high pressure oil between
the eccentric bushing and the crankshaft eccentric;
Figure 9 is an elevational view of a typical mechanical
press utilizing the present invention; and
Figure 10 is a schematic, cross-sectional view of one of the
U-shaped seals of the present invention.
Corresponding reference characters indicate corresponding
parts throughout the several views. Although the drawings
represent embodiments of the invention, the drawings are not
necessarily to scale and certain features may be exaggerated or
omitted in order to better illustrate and explain the present
invention.
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2 1 ~0 20 $
The adjustable stroke connection of the present invention is
ideally suited for a wide assortment of configurations of
mechanical, stamping presses. As is conventional, a mechanical
press 110 (Fig. 9) typically includes a crown portion 115, a bed
portion 117 having a bolster assembly connected thereto, and
uprights 113 connecting crown portion 115 with the bed portion
117. Uprights 113 are connected to or integral with the
underside of the crown and the upper side of the bed. A slide
119 is positioned between uprights 113 for guided, reciprocating
movement relative to the bed. Tie rods (not shown), which extend
through the crown, uprights and bed portion, which are attached
at each end with tie rod nuts. Leg members 118 are formed as an
extension of the bed and are generally mounted on the shop floor
by means of shock absorbing pads.
In order to power the reciprocating motion of the slide 119,
a drive mechanism 114 for the press is provided. A suitable
mechanism includes a drive motor 116 attached by means of a belt
to an auxiliary flywheel 120 attached to crown 115. The
auxiliary flywheel 120 is connected to a main flywheel 112, which
in turn is selectively engaged by the clutch of the combination
clutch/brake to power the rotation of the press crankshaft 14,
which in turn effects slide motion via connections extending
between the slide and crankshaft. This description of press 110
and its drive mechanism is merely illustrative. A wide variety
of mechanical presses are well known in the art, and the instant
invention can be utilized with any mechanical press that utilizes
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CA 02190208 2001-11-13
a crankshaft type device to achieve reciprocating motion of a
press component. An example of a mechanical press is disclosed
in U.S Patent No. 5,189,928 entitled "ADJUSTABLE STROKE PUNCH
PRESS".
Referring now to Fig. 1, there is schematically shown in
perspective view a portion of the crankshaft, its associated
eccentric bushing, and the connection which is powered by
crankshaft rotation. The connection may be formed of a bottom
portion and a cap, and the bottom portion of connection member 10
would typically be attached in a suitable fashion to the press
slide. The crankshaft 14 includes a cylindrical main portion 16
axially centered on the crankshaft axis of rotation and a second
eccentric member such as a cylindrical eccentric 18 rotatably
fixed thereto or integrally formed therewith. Although only one
crankshaft eccentric is shown, multiple eccentrics would be
provided along the axial length of crankshaft 14 to cooperate
with additional connections which are not shown.
Ringing crankshaft eccentric 18 is a bronze eccentric
bushing 20. Figs. 2A, 2B and 3 better illustrate the
configuration of these components, wherein crankshaft main
portion 16 ie shown in dashed lines. During normal press
operation, as crankshaft 14 rotates, the eccentric bushing 20 is
held in place on crankshaft eccentric 18 (i.e., rotates
therewith) by a press fit or interference fit around the
crankshaft eccentric circumference at 22 that is sufficient to
transmit the torque required to accomplish the stamping or
forming operation. Oil is supplied to lubricate the rotation of
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eccentric bushing 20 relative to connection 10 For example, oil
passes through the top of the connection or the connection cap at
conduit 24 and into a .003" to .005" radial clearance 26 to
provide an oil film on which eccentric bushing 20 rotates Fig.
4A.shows how oil, such as at 125 p.s.i., can be delivered through
hose 25 and conduit 24 to radial/running clearance 26 to
lubricate the connection movement. At this point of operation,
the conduits in Fig. 4A indicated in dashed lines within
crankshaft 14 and eccentric 18 are not being used in a manner to
effect stroke adjustment described further below. As crankshaft
14 and its co-rotating eccentric bushing 20 rotate relative to
connection 10, the connection 10 moves up and down to effect a
reciprocating motion of slide 119.
When a change or adjustment in the stroke of slide 119 is
desired, rotation of crankshaft 14, and therefore motion of the
slide, is stopped, and the oil supply through conduit 24 at the
top of connection 10 is halted. Then, high pressure oil is
supplied through crankshaft 24 such as through axial bore 28 and
one or more cross bores 29, to the inside diameter of eccentric
bushing 20. The high pressure oil is expected to be, but not
limited to between 7,000 p.s.i. to 10,000 p.s.i., and is
distributed circumferentially around crankshaft eccentric 18.
Seals 100, 102 may be provided, such as along the axial edges at
the inside diameter of bushing 20, to prevent escape of the high
pressure oil. The high pressure oil tends to circularly expand
bushing 20 to relieve the press fit between crankshaft eccentric
18 and eccentric bushing 20. The high pressure oil in effect
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2~~020 0
creates a small radial clearance between eccentric 20 and
crankshaft eccentric 18 indicated at 31, and creates a temporary
press fit or interference fit situation at 33, circumferentially
between eccentric bushing 20 and connection 10. (See also Fig.
4B) Lubricated, radial clearance 31 allows crankshaft 14 to
rotate relative to eccentric bushing 20, which, due to its
temporary press fit with connection member 10 does not rotate.
As crankshaft 14 rotates, the crankshaft main portion 16 shifts
into a different position relative to the eccentric bushing 20,
which in turn effectively changes the stroke length of connection
10 to a desired length. When the adjustment is completed, the
high pressure oil at 31 supplied through crankshaft 14 is halted,
allowing the eccentric bushing 20, due to the resiliency of its
metal construction, to return to its press fit with the
crankshaft eccentric (second eccentric member 18) to again allow
rotation of the crankshaft to reciprocate the connection and
thereby continue stamping operations.
Figs. 2A and 2B disclose how a rotation of crankshaft 14
along with eccentric bushing 20 through 180° achieves, as shown,
a 2.5" stroke length. Naturally, other stroke lengths are
possible within the scope of the invention.
Fig. 5 discloses an alternate embodiment of the invention,
and this embodiment is shown during stamping operations. In this
embodiment, an additional connection bushing 11 is interposed
between connection 10 and bushing 20, and connection bushing 11
fits in a circumferential groove provided in the radially outer
portion of eccentric bushing 20. Oil can be introduced into
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radial clearance 26 to furnish an oil film which facilitates free
rotation of the crankshaft and its eccentric bushing relative to
connection 10 and its associated bushing 11. In this embodiment,
seals 35 prevent escape of high pressure oil from between
crankshaft eccentric 18 and eccentric bushing 20. During stroke
adjustment, high pressure oil is supplied through multiple cross
bores 29 fed by an axial bore 28. Axial bore 28 extends through
the crankshaft to each connection further along the axial length
of the crankshaft.
To aid in preventing eccentric bushing 20 from possibly
"egg-shaping" and developing uneven stresses when it is expanded
to relieve its press fit with crankshaft eccentric 18 as
described above, a variety of eccentric bushing shapes may
possibly be employed.
For example, Fig. 6A is an axial, cross-sectional view of an
eccentric bushing 20 in which the eccentric lobe portion 40
includes an internal cavity 41 in fluid communication with the
eccentric bushing internal opening 43 which receives crankshaft
eccentric 18. When the high pressure oil is introduced
circumferentially around the crankshaft eccentric, the high
pressure oil provides a force directed radially outwardly (as
indicated by the arrows 42), and the force also acts within lobe
cavity 41 as shown. Fig. 6B is a cross-sectional view,
conceptually similar to the view of Fig. 6A, in which the outer
lobe portion has an I-beam type configuration with a central rib
45. The forces produced by the high pressure oil are again
indicated at 42. Fig. 6C discloses the eccentric bushing of Fig.
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6B in side view wherein the eccentric lobe is shown as including
rib 45 recessed from the axial edges of the eccentric bushing.
Fig. 6D discloses still another embodiment in axial cross-
sectional view, wherein the eccentric lobe 47 of the eccentric
bushing 20 is hollow.
Referring now to Fig. 7, there is shown still another aspect
of the present invention which allows a conventional rotary
union, as opposed to a special high pressure rotary union, to be
used to introduce high pressure oil used for expansion of the
eccentric bushing. The majority of the embodiment shown in Fig.
7 is conceptually similar to the embodiments described above. A
cylindrical crankshaft eccentric 52 is integral with crankshaft
main portion 50 and ringed by an eccentric bushing 54 which is
press fit at 55 on eccentric 52. A connection bushing 56 rings
eccentric bushing 54 and is provided with a small radial
clearance at 60. Connection bushing 56 is press fit within an
opening provided between connection cap 63 and connection bottom
62, which is attached to the press slide.
Axially extending through crankshaft main portion 50 is bore
65 from which branch off cross bores 67 radially extending
through crankshaft eccentric 52. Axial bore 65 extends to the
left in Fig. 7 toward other connections. To realize the high
pressure oil used to expand eccentric bushing 54 without
requiring that oil at these high pressures be introduced through
a rotary union into the crankshaft, an intensifier with a 10:1
(or other) ratio is provided. Within the end of axial bore 65 is
an intensifier rod or plunger 69 which is sealed by seal 70
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seated in an internal groove of the crankshaft. Alternatively,
the seal could be mounted on plunger 69. Plunger 69 ends at a
circumferentially sealed piston 72. Oil, for example at 1,000
p.s.i., passes from 74 into rotary union 76 and into chamber 78
where it acts against piston 72 to force plunger 69 to move to
the left. During plunger movement, air passes through vent 79.
As plunger 69 has a cross-sectional area one-tenth or other
fraction of the cross-sectional area of piston 72, oil already
within axial bore 65 and cross bores 67 is raised to a pressure
of about 10,000 p.s.i. by piston movement. The piston and
plunger are designed so as to have sufficient stroke to allow
enough oil to be displaced to furnish expansion of the eccentric
bushings of all of the connections. When high pressure oil
within cross bores 67 moves into the inner-diameter cavity of
eccentric bushing 54 to radially expand the bushing, seals 81
prevent the oil from escaping or leaking from the closed system.
Fig. 8 is a partial, axial cross-sectional view of another
method of sealing high pressure oil used to expand the eccentric
bushing. In this embodiment, O-ring face seals 84 mounted on
eccentric bushing 86 cooperate with radially aligned walls of
ribs 88 projecting from crankshaft eccentric 90. Or, the seals
could be provided on ribs 88 to protect against oil leakage.
Other sealing configurations could also be employed within the
scope of this invention.
The present invention includes two seals 100 and 102 (Fig. 1
and 10) made of a high coefficient of friction material which,
when pressurized, creates a holding force or mechanism such that
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both the eccentric bushing 20 and second eccentric member 18 lock
together until there is a press fit or interference fit created
in clearance 26, located between connection member 10 and
eccentric bushing 20.
. Clutch torque, during rotation of crankshaft 14 will have to
overcome the high coefficient of friction of this feature thereby
created between the eccentric member 18 and eccentric bushing 20.
This feature allows multiple eccentrics to displace at the same
time with the same angle, without any additional mechanical
teeth, sprockets, or other mechanisms to ensure proper timing or
displacement therebetween. This sealing arrangement, with a high
coefficient of friction, further reduces parts and simplifies the
design. There are no other mechanical parts necessary to hold
the position of multiple eccentrics relative to each other, so
that the slide remains parallel after the press stroke change is
completed.
An additional feature of the invention is that the same
adjustable stroke connection may be utilized between the
crankshaft and a balancer, thereby press balance may be
maintained. Therefore the types of connection members utilizable
with the present invention may be those of a normal connection
arm or other link to a press part, such as a dynamic balancer.
Although the adjustable stroke mechanism of the present
invention utilizes a single oil passageway through the
crankshaft, it may be possible to have two different oil
passageways coming from opposite sides, one to operate the
adjustable stroke connection mechanism of the present invention
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related to slides, and the other passageway operating stroke
adjustment for a balancing arrangement.
One type of seal found to be useful in the present invention
is that of a U-type seal. This type of seal operates by the
action of the internal fluid pressure spreading the lips of the
seal. This movement creates a braking force between the
eccentrics and journal which allows a clamping force to be
developed. It has been found that a U-cup or U-shaped seal
operates better than any other type of seal so far utilized.
Figure 10 shows a typical U-shaped seal (100,102) while pressure
is applied between the two eccentric members. The clamping force
increases with pressure. The holding force therefore can be
easily manipulated for whatever torque is required by the device.
While this invention has been described as having a
preferred design, the present invention can be further modified
within the spirit and scope of this disclosure. This application
is therefore intended to cover any variations, uses, or
adaptations of the invention using its general principles.
Further, this application is intended to cover such departures
from the present disclosure as come within known or customary
practice in the art to which this invention pertains and which
fall within the limits of the appended claims.
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