Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to fluid-operated chucks in general, and to fluid oper-
ating mechanism for rotary chucks in particular.
C:onventional fluid operating mechanisms for rotary chucks provide a cylinder
with a piston therein defining opposite chuck closing and opening cylinder ends,and a fluid coupling. The cylinder is adapted for mounting on the chuck-carrying
. .
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._ _ _ e ___ _ _ _. ..__._ _ . ___ _,
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11;3;3~ ~3
spindle of a lathe or the like so as to be turnable therewith, while the piston
is adapted for operative connection with the jaw actuator of the chuck, and the
coupling has companion parts of which one part turns with the cylinder, and the
other part is held against rotation and is connectible with two fluid conduits,
with these coupling parts having having suitable ports that form together with
the conduits fluid passages to the opposite cylinder ends. There is also provided
valve mechanism which is operable to connect either fluid passage with a fluid
pressure source and simultaneously vent the other passage for closing and open-
ing an associated chuck.
Among these fluid operating mechanisms are those of fluid lock type which
act to lock the operating fluid in either cylinder end whenever the pressure of the
supplying fluid drops below a safe work gripping pressure from any cause what-
ever, including a leak or break anywhere in the fluid passages. This is achieved
by two check valves and associated plungers, of which each check valve is
interposed in one of the passages and is normally closed to block fluid flow
from the respective cylinder end, and the associated plunger is subjected to
fluid in the other passage, with this plunger acting to open the check valve
when subjected to such fluid on operating valve mechanism to admit fluid to
this other passage and simultaneously vent the opposite passage.
The invention is concerned with fluid operating mechanism of fluid lock
type for high-low operation of a chuck,i.e., operation of a chuck in two stages
at successive high and low fluid pressures in contrast to a conventional chuck
operation of a single stage at a single fluid pressure. High-low operation of a
chuck iS indicated when a particular machining operation on work calls for a
heavy work grip by the chuck for an initial part of the machining operation, foll-
owed by a lighter work grip for the remaining part of the machining operation as,
for example~ in reducing a relatively thick wall of hollow work in an initial
rough-machining operation for which a relatively heavy work grip is required,
--2--
1 followed by a lighter grip on the work when the same becomes so fragile that the
heavy work grip, if it were continued during finish-machining of the work, would
most likely permanently distort or fracture the work.
Fluid operating mechanism(~f fluid lock type for high-low chuck operation is
disclosed in the patent to Smithson No. 3,735,670, dated May 20, 1973. This
prior mechanism has the usual fluid passages to the chuck closing and opening
cylinder ends, with a check valve in;,each passage and its associated plunger
subjected to fluid in the other passage. These passages serve for supplying
fluid to the cylinder for operation of the piston therein as in the aforementioned
10 conventional chuck operation in which the admission of operating fluid to either
cylinder end for chuck closing and chuck opening is accompanied by venting of
the other cylinder end as a condition precedent to proper functioning of the
dleck valves, i.e., the passages serve in this case to apply fluid to the chuck-
closing cylinder end for the high stage of a high-low chuck operation, as well as
to apply fluid to the chuck-opening cylinder end for opening the chuck, with the
other cylinder end being vented during either of these chuck operations. However,
these two fluid passages are of no avail for supplying the cylinder with fluid for
the change from the high stage to the low stage of the high-low chuck operation.
This is due to the fact that the check valves and their associated plungers do
20 not permit fluid flow in either of these two passages which would meet the im-
perative requirement of a high-low chuck operation that the change from the high
stage to the low stage of such an operation be effected by reducing the pressure
of the operating fluid in the chuck-closing cylinder end without, however, evac-
uating this fluid from this cylinder end that would release the work from the chuck.
Thus, such reduction of the pres sure of the fluid in the chuck-closing cylinder end ,
i.è~., without evacuation of the fluid therefrom, would require in any event open-
ing of the associated check valve. However, it is well known that this check
valve will open only if the fluid passage in which it is interposed is vented,
113;3~.}3
wherefore any attempt at opening this check valve for mere pressure reduction
of the operating fluid in the chuck-closing cylinder end without any fluid evac-
uation therefrom is doomed to failure.
For supplying the cylinder with fluid for the change from the high stage to
the low stage of a high-low chuck operation, this prior mechanism relies on a
bypass around the check valve in the passage to the chuck-closing cylinder end,
and a rather intricate system of control valves which are associated with the by-
pass and function, at the conclusion of the high stage of an operation, to first
bleed fluid from the chuck-closing cylinder end until the pressure of the fluid
10 therein drops from a preset high pressure to a given minimum pressure, and then
immediately apply to the bypass fluid of a preset low pressure higher than the
minimum pressure for the low stage of the operation. The bypass and the control
valves associated therewbth perform several functions which are imperative for
high-low chuck operation and which the fluid passages with the interposed check
valves and their associated plungers could not perform. Thus, and as already
mentioned, one of these imperative functions is the bleeding of fluid from the
Ghuck-closing cylinder end for the sole purpose of reducing the pressure of the
fluid therein. Another one of these imperative functionslies in bleeding fluid from
the chuck-closing cylinder end until the pressure of the fluid therein drops from
20 the preset high pressure to the specified minimum pressure, and then applying
to this cylinder end fluid at the preset low pressure for the low stage of the
high-low chuck operation.This latter function also takes into account that mere
reduction of the pres sure of the fluid in the chuck-closing cylinder end from the
preset high pressure to the preset low pressure would not bring about the de~iired
changeover from the high stage to the low stage of the chuck operation because
this preset low pressure, while fully adequate to hold the work at the desired
lighter grip for the low stage of the operation, is mostly too high to permit the
operating chuck parts to break loose from their tight binding engagement ensuing
1~;33~13
from the initial heavy grip exerted on the work. Accordingly, the pressure of the
operating fluid in the chuck~closing cylinder end has to be reduced from the
preset high pressure to a minimum pressure which must be sufficiently low that
the chuck will respond to it in relaxing the heavy work grip, and only then is fluid;
at the preset low pressure applied to the chuck-closing cylinder end for the low
stage of the chuck operation. Still another and highly important one of these im-
perative functions lies in maintaining in the chuck-closing cylinder end through-
out the changeover from the high stage to the low stage of the operation fluid of
a pressure at which the chuck will retain a positive grip on the work.
While this mechanism performs generally satisfactory, it is also highly com-
plex structurally and is even deficient in a few respects. Thus, the provision in
this mechanism of the bypass with the system of associated control valves makes
for a highly complex construction and correspondingly high cost of the mechanism.
Further, the operational safety afforded by the check valves prevails only during
the high stage, but is totally lacking during the low stage, of an operation.
Also, with the bypass and the system of associated control valves being closely
related with the one fluid passage to the cylinder end which is the designated
chuck-closing cylinder end, there is no possible way to convert the mechanism,
by mere reversal of two fluid connections, to high-low chuck operation with the
2 0 other cylinder end serving a s the chuck-closing cylinder end .
It is an important object of the present invention to provide fluid operating
mechanism of fluid lock type which lends itself to high-low chuck operation, and
in which the only available fluid flow paths to and from the cylinder ends are
via the check valves of the fluid lock and the two passages in which they are i s i
interposed. This fluid operating mechanism, by lacking the bypass and the intricate
associated control valves of the aforementioned prior mechanism, is for this
reason alone vastly superior to this prior mechanism in the matter of structural
simplicity and low cost. rurther, by passing all operating fluid through either
1~3;~3
check valve of the fluid lock in the present mechanism, the safety in chuck oper-
ation afforded by the check valves prevails throughout each high-low chuck oper-
ation and not only during the high stage of such an operation as in the prior mech-
anism. Also, and in direct contrast to the prior mech~si;sm,the present mechanism
lends itself to ready conversion for operation with either cylinder end as the chuck
closing cylinder end by simply reversing two connections in the fluid lines to the
cylinder ends .
It is another object of the present invention to provide fluid operating mechan- -.
ism of fluid lock type in which the only fluid paths to the cylinderl ends are via
10 the check valves and the two passages in which they they are interposed, with
the key to high-low chuck operation lying in the arrangement of the check valve
and plunger elements of the fluid lock such that the plunger elements perform their
designated valve opening function not only on accustomed venting of the respective
fluid passages, but also without venting these passages. With the plunger elements ~:
thus able to function for opening~ their associaYed check valves without venting the
passages in which they are interposed, that most unique and hitherto unattainable
step in high-low chuck operation of bleeding some minute quantities of fluid from
the chuck-closing cylinder end through the associated check valve for merely
lowering the pressure of the fluid therein from the prevailing high pressure, is
20 attainable by opening this check valve without venting the passage in which it is
interposed and, instead,admitting to this passage fluid at a lower control pressure
with which the fluid in the chuck-closing cylinder end will blend for a drop of
its pressure to this lower control pressure.
It is a further object of the present invention to provide fluid operating mech-
anism of fluid lock type in which fluid of the control pressure admitted to the `
"primary" passage to the chuck-closing cylinder end, while serving for the primary
purpose of blending with the fluid in the chuck-closing cylinder end in order to
reduce the pressure therein as aforementioned, also inherently opposes opening of
the check valve in the primary passage by its plunger on accustomed admission
to this end of operating fluid to the "secondary" passage to the chuck-opening c~- ir =
~1;33;~3
cylinder end, wherefore for proper performance of the mechanism the fluids ad-
mitted to these primary and secondary passages must be effective so that, on
the one hand, the valve opening action of the plunger by the fluid in the sec-
ondary passage will prevail over the opposition to such plunger action by the
fluid in the primary passage, and on the other hand, the fluid in the primary
passage and chuck-closing cylinder end must prevail over the fluid in the sec-
ondary passage and chuck-opening cylinder end to hold the associated chuck
closed so as not to relinguish its positive work grip even for an instant. To
achieve this end, the plunger associated with the check valve for the chuck-
10 closing cylinder end is featured as a stepped plunger, of whch the larger faceis subjected to fluid in the secondary passage, and the smaller face is subjected
to fluid in the primary passage between the check valve therein and the assoc-
iated cylinder end, with the areas of the larger and smaller faces of the plunger
being of a given ratio. Thus, assumimg that the ratio of the plunger faces be 5
to 1, and that the pressure in the fluid in the primary passage be lOOlbs. per
inch2, the check valve in the latter will be opened by the plunger on admitt-
ing to the secondary passage fluid of a pressure over 20 lbs. per inch2, as
will be readily understood.
AIDther object of the present invention is to provide fluid operating mechanism
20 of fluid lock type for high-low chuck operation, of which at least the plunger
associated with the check valve for the chuck-closing cylinder end is of the
featured stepped kind with a given area ratio between its larger and smaller
faces, and to operate the mechanism according to a method which involves,
for chuck performance at the high stage of a high-low operation, applying fluid
of a given high pressure to the chuck-closing cylinder end via its passage and
simultaneously opening the other passage for venting the chuck-opening cylinder
end, and changing to chuck performance at the low stage of a high-low chuck
3Z43
operation by first applying to the passages to the chuck closing and opening
ends operating fluid of second and third pressures, respectively, of which the
second and third pressures are lower than the given high pressure and are of
a ratio smaller than the area ratio of the faces of the stepped plunger to thereby
cause opening of the check valve for the chuck-closing cylinder end and a press-
ure drop of the fluid in the latter from the preset high pressure to the second
pressure, and then venting the passage to the chuck-opening cylinder end while
supplying the passage to the chuck-closing cylinder end with operating fluid of
a fourth pressure which is lower than the given high pressure but not lower than
10 the second pressure. In thus operating the mechanism, the chuck perfolmance is
changed from the high stage to the low stage of the high-low chuck operation
essentially as in the aforementioned prior mechanism, with this important diff
erence, however,that in the present mechanism the only fluid paths to and from
the cylinder ends are via the check valves and the two passages in which they
are interposed. Thus, in the present mechanism the pressure of the fluid in the
chuck-closing cylinder end is reduced from the given high pressure to the spec-
ified second pressure while fluid of the specified third pressure is applied to
the chuck-opening cylinder end, wherefore the effective pressure of fluid on the
piston in the cylinder is the differential between these second and third press-
2Q ures, and this pressure differential has the same effect as the explained minimum -
fluid pressure in the chuck-closing cylinder end of the prior mechanism, namely
to relax the chuck's heavy work grip sufficiently so that the chuck will exert a
lighter grip on the work on subsequently venting the chuck-opening cylinder end
and applying to the chuck-closing cylinder end fluid of a given low pressure
for the chuck performance at the low stage of the high-low chuck operation.
Further objects and advantages will appear to those skilled in the art from
the following, considered in conjunction with the accompanying drawings.
1133;2~;~
In the accompanying drawings, in which certain modes of carrying out the
present invention are shown for illustrative purposes:
Fig. 1 is a longitudinal section throufg fluid operating mechanism which
embodies the invention;
Fig. 2 is a section through the mechanism taken substantially on the line
2-2 of Fig. l;
Fig. 3 is a diagrammatic view of fluid operating mechanism, including a
system of control valves associated with the mechanism/ for high-low chuck
operation according to the invention;
Fig. 4 is a diagrammatic view of fluid operating mechanism, including a
modified system of control valves therefor, for high-low chuck operation in acc-
ordance with the invention; and
Fig. 5 is a diagrammatic view of fluid operating mechanism, including an-
other modified system of control valves therefor, for high-low chuck operation
a ccording to the invention .
Referring to the drawings, and more particularly to Figs. 1 and 2 thereof,
the reference numeral 10 designates a fluid coupling of a chuck operating mech-
anism. The coupling 10 provides stationary and rotary companion parts 12 and 14,20with the rotary part having a cylindrical journal 16 for its rotary support in anti-
friction bearings 18 in the stationary part 12. The rotary coupling part 14 provides
a cylinder 20 with a piston 22 which defines in the cylinder opposite chuck-
closing and chuck-opening ends 24 and 26. The piston 22 is provided with a rod
extension 28 which is formed as a sleeve owing to the provision of the exemplarycenter aperture 30 in the coupling, with this sleeve extension 28 being through a
draw bar 32 connected in usual manner with a jaw actuator of an associated chuck(not shown). The chuck is customarily mounted on the front end of a power spindle
in a lathe or the like (neither shown), and the coupling 10 is with its rotary part
14 mounted on the rear end of the pav~er spindle in usual manner
_g
~33~3
Operating fluid is applied to the cylinder 20 from a suitable fluid pressure
source via fixed conduits 34,36 that lead to the stationary coupling part 12, and
suitable orifices in the coupling parts that lead to the opposite ends of the cyl-
inder. Thus, operating fluid is admitted, under suitable valve control, to the
chuck-closing cylinder end 24 via a fluid passage 38 which is formed by the fixed
conduit 34 that leads to a port 39 with an annular groove 40 in the stationary
coupling part 12, and a continuing orifice 42 in the coupling parts 12 and 14 that
extends all the way to the chuck-closing cylinder end. Operating fluid is also
admitted to the chuck-opening cylinder end 26 via a fluid passage 46 which is
formed by the other fixed conduit 36 that leads to a port 47 with an annular groove
48 in the stationary coupling part 12, and a continuing orifice 50 in the coupling
parts 12 and 14 that extends all the way to the chuck-opening cylinder end 26.
The orifices 42 and 50 are in this instance wholly contained in the coupling parts ~2
12 and 14, but they are represented in part by lines which in Fig. 1 extend outside
the coupling parts for a clear demonstration not only of their continuity to the
respective cylinder ends, but also of their coordination with fluid lock units 52
and 54 which are shown diagrammatically in Fig. 1, with each of these units
having operating valve and associated plunger elements . Thus ,the unit 52 provides
a check valve 56 and an associated plunger 58, with the plunger being slidable
in a cylindrical passage 60 in a casing 62, and having an axial shank 64 for
opening the valve 56 on subjection of the plunger 58 to certain fluid pressure
described hereinafter. The orifice 42 to the chuck-closing cylinder end 24 is
interrupted for interposition thereat of the check valve 56 and of the end of the ~.-
passage 60 in the casing 62 next to the check valve 56. The opposite end of
the passage 60 is through a bran~horifice 68 connected with the orifice 50 behind
a check valve 70 therein which is part of the other fluid lock unit 54. This
other fluid lock unit 54 provides the check valve 70 and an associated plunger 72r
--10--
in a cylindrical passage 74 in a casing 76, with the plunger 72 having an axial
shank 78 for opening the valve 70 on subjection of the plunger 72 to certain fluid
pressure described hereinafter. The orifice 50 to the chuck-opening cylinder end
26 is interrupted for interposition of the check valve 70 and of the end of passage
74 in the casing 76 neEt to the check valve 70. The opposite end of the passage
74 is through a branch orifice 84 connected with the orhfice 42 behind the check
valve 56 therein. The check valves 56 and 70 are arranged to open for fluid ad-
mission to, but to close for blocking fluid flow from, their associated chuck-clos-
ing and chuck-opening cylinder ends 24 and 26, and the plungers 58 and 72 func-
10 tion, on being subjected to fluid pressure as described hereinafter, to open theirassociated check valves 56 and 70.
In accordance with an important aspect of the present invention, the plunger
58 of the fluid lock unit 52 is a stepped plunger which is double-acting in perform-
ing its designated function of opening the associated check valve 56. Thus, the
plunger 58 is formed in stepped cylindrical parts 88 and 90 with diametrically smal- -
ler and larger ends or faces 92 and 94, respectively, and the passage 60 in the .
casing 62 is also formed in stepped sections 96 and 98 for sliding reception of
the respective plunger parts 88 and 90, with the diametrically smaller passage .~ ~
section 96 and plunger part 88 being next to the associated check valve 56 (Fig 1) .
20 The plunger 72 of the other fluid lock unit 54 is in this instance also a stepped
plunger, being formed in similar stepped cylindrical parts 100 and 102 with dia-
metrically smaller and larger ends or faces 104 and 106, respectively, and the
passage 74 in the casing 76 is also formed in stepped sections 108 and 110 for
sliding reception of the respective plunger parts 100 and 102, with the diametrically
smaller passage section 108 and plunger part 100 being next to the associated
check valve 70.
The merit of a stepped plunger lies in its function to open the associated
check valve in a fluid passage to a particular cylinder end on admitting operating
1133;2~;~
fluid into the passage to the other cylinder end with or without venting of the
other passage. Thus, assuming that for closure of an associated chuck the chuck-
closing cylinder end 24 is supplied with fluid of a given high pres sure via the
described passage 38, the chuck will be opened on operating valve mechanism
to admit fluid under pressure to the chuck -opening cylinder end 26 via the des-
cribed passage 46 and simultaneously vent the chuck-closing cylinder end 24 via
the passage 38. Under the circumstances, the check valve 56 will be opened by
the plunger 58, be~ause the face 92 of this plunger is no longer subjected to any
fluid pressure the moment the passage 38 is vented, so that the pressure of the
fluid admitted to the chuck-opening cylinder end, which is then the only fluid
pressure acting on the plunger 58 and more particularly on the face 94 thereof,
will open the check valve 56 at any pressure of the fluid then admitted to the
chuck-opening cylinder end, as will be readily understood. Assuming now that the
chuck-closing cylinder 24 is suppliedvia the passage 38 with fluid of a given
high pressure at which the associated chuck is closed and holds work with a
firm grip,the check valve56 associated with the chuck-closing cylinder end 24
can be opened without venting the fluid passage 38, by admitting fluid of a
first control pressure to the passage 46 and chuck-opening cylinder end 26 and
applyin~ to the passage 38 fluid of a second control pressure, the only require---n~
ments being that these contro:bare lowerthan the given high pressure:-and may
be as low as desired, and the total pressure of fluid on the larger face 94
of the plunger 58 is in excess of the total pressure of fluid on the smaller face
92 thereof, with the latter requirement being met as long as the second and
first control pressures are of a ratio smaller than the ratio at which the area
of the larger face 94 of the plunger 58 is larger than the area of the smaller
face 92 thereof. In this connection, it is to be understood that fluid of the
given high pressure is in this instance applied to the passage 38 until the
--12--
~ ~;33~
fluid of the second control pressure is applied to this passage and ordinarily
cause closure of the check valve and, hence, entrapment of the fluid of high
pressure in the chuck-closing cylinder end. However, since in this example
fluid of the first control pressure has first been applied to the passage 46 and
the force it exerts on the larger plunger face 94 overpowers the counterforce
of the fluid acting on the smaller plunger face 92, the plunger prevents actual
closure of the check valve 56 in this case andJ instead, keeps the same open.
On the other hand, if the fluid of the second control pressure were applied to
the passage 38 before the fluid of the first control pressure is applied to the
passage 46, the check valve 56 will actually close on the application of the
second control pressure and will be opened with the application of the first
control pressure, as will be readily understood. For a better understanding of the
action of the stepped plunger 58, let it be assurned that the ratio between the
larger and smaller areas of the opposite faces 94 and 92 be 5 to 1, for example,
and that the first control pressure of the fluid acting on the larger plunger face
94 be 20 lbs. per inch2, the check valve 56 will be opened without venting the
passage 38 to the chuck-closing cylinder end if the second control pressure of
the fluid acting on the smaller plunger face 92 is less than 100 lbs. per inch .
In thus admitting fluid of the described first control pressure to the passage 46
and chuck-opening cylinder end 26, and also admittir3g fluid of the described
second control pressure to the other passage 38 in lieu of venting the latter,
the plunger 58 will open the associated check valve 56 and thereby release the
fluid of high pressure in the chuck-closing cylinder end 24 for assimilation
with the fluid of the second control pressure admitted to the passage 38 and
establishment of a common pressure, i.e., the second control pressure, for
all fluid in the passage 38 and chuck-closing cylinder end 24, as will be readily
understood .
--13--
1133~3
The fluid lock units 52 and 54, while shown diagrammatically and outside
the fluid coupling 10 in Fig. I, are in this instance arranged within the fluid
coupling 10, and more particularly within the rotary coupling part 14 as shown
in Fig. 2 in which parts of the units 52 and 54 are denoted by the same refer-
ence numerals as their counterparts in Fig. 1.
Reference is now had to Fig. 3 which shows diagrammatically chuck oper-
mechanism
ating/120 which includes the fluid coupling 10 of Figs. 1 and ~-, and which
lends itself to high-low chuck operation. Thus, the fluid coupling of the diagram=
matic showing in Fig. 3 indicates the stationary and rotary companion parts 12
10 and 14 with the cylinder 20 in the rotary coupling part 14, and the piston 22
which devides the cylinder 20 into the opposite chuck-closing and chuck-opening
cylinder ends 24 and 26. Further shown in Fig. 3 are the fluid passages 38 and
46 with their respecrive conduits34 and 36 to the fluid coupling 10 and their
respective orifices 42 and 50 in the coupling, with the fluid lock units 52 and 54
being also shown in association with the respective fluid passages 38 and 46.
rE~e chuck operating mechanism also includes valve mechanism in the form of
several valves 122,124, 126 and 128 which may be operated for high-low chuck
operation . Available in this example for operation of the mechanism~ are three
fluid sources of different operating pressures denoted PH, PL and PM, of which
20 "H", "L" and "M" signify "high" pressure, "low" pressure and "minimum" press .~e,
ure, respectively, with the fluid source PH being connected to the valve 124
and the fluid sources PL and PM being connected to the val~ae 128. Valve 128
has an outlet 130 which through a conduit 132 is connected with an inlet 134
in the valve 124. Valve 124 has also an outlet 136 which through a conduit
138 is connected with an inlet 140 in the valve 122. Valve 122 also has a
vent opening 142 and an outlet 144 which is connected with the conduit 34
of the fluid passage 38 to the chuck-closing cylinder end 24. Branching from
the conduit 132 is a conduit 146 which is connected with an inlet 148 in
valve 126 which also has a vent opening 150 and an outlet 152 which is conn~
--14--
ected with the conduit 36 of the fluid passage 46 to the chuck-opening cylinder
end 26. Interposed in the branch conduit 146 is a check valve 154 which opens
to admit fluid above a given pressure to the valve 126, and is normally closed
to block fluid flow from the valve 126 to the conduit 132. This valve 126 is nor-
mally closed by a spring 156 which is calibrated to permit opening of the valve
by fluid in the conduit 132 above the aforementioned given pressure.
Following is a description of a high-low chuck operation by the mechanism
120. Let it be assumed that the associated chuck is held open by connection of
the chuck-opening cylinder end 26 with the fluid pressure source PL and simul-
10 taneous venting of the chuck-closing cylinder end 24, with the connection of the c~ -
chuck-opening cylinder end 26 with the fluid pressure source PL being via the fluid
passage 46, valve 126, conduit 146 with the interposed check valve 154, and ~ ~r~'
conduit 132, with the sliding member 160 of the valve 126 being to this end
shifted to its other position against the force of the return spring 162 on energiz-
ing a relay 158, and venting of the chuck-closing cylinder end 24 being via the
fluid passage 38 and the vent opening 142 in valve 122 on energizing a relay 164
and thereby shifting the member 166 c~ valve 122 to its other position against
the force of the return spring 168. A high-low chuck operation by the mechanism,
and more particularly the high stage thereof, will be started by connecting the
20 chuck-closing cylinder end 24 with the fluid pressure source PH on deenergizing
the relay 164 for spring return of the member 166 of valve 122 to the position
shown, and venting the chuck-opening cylinder end 26 via the fluid passage 46
and through the vent opening 150 in valve 126 on deenergizing the relay 158 for
spring return of the valve member 160 to the position shown . The chuck will be
powert3driven during the high stage of its operation. When the high stage of the
chuck operation is concluded, the power drive of the chuck is preferably stopped
and the mechanism is operated for changing from the high stage to the low stage
of the chuck operation, with the power drive of the chuck being resumed when
~133Z43
the chuck resumes its operation at the low stage. For changing from the high
stage to the low stage of the chuck operation, the chuck-opening cylinder end
26 and the fluid passage 38 are successively connected with the fluid pressure
source PL and PM, respectively, with the chuck-opening cylinder end 26 being
connected with the fluid pressure source PL via conduit 132, the branch conduit
146 with the interposed check valve 154, valve 126 and fluid passage 46, on ener-
gizing the relay 158 and thereby shifting the member 160 of valve 126 to its other
position against the force of the return springl62, and the fluid passage 38 being
connected with the fluid pressure source PM via conduit 132, valve 124, conduit
10 138 and valve 122 on energizing a relay 170 and thereby shifting the member 172
of the valve 128 to its other position against the force of the return spring 174,
and further energizing a relay 176 and thereby shifting the member 178 of the
valve 124 to its other position against the force of the return spring 180. In thus
connecting the chuck-opening cylinder end 26 and the fluid passage 38 with the
respective fluid pressure sources PL and PM, the pressure of the fluid acting on
the larger face 94 of the plunger 58 (Fig. 1) is that of PL minus the pressure
of fluid required to open the spring-closed check valve 154 (Fig. 3~, while the
pressure of the fluid acting on the smaller face 92 of the plunger 58 is that of . -~
the fluid source PM. Further, the closing spring 156 of the check valve 154 is
20 calibrated so that the pressure of fluid in the conduit 132 required to overpower
this spring 156 and open the valve 154 must be in excess of PM, wherefore on
connecting the fluid passage 38 with the fluid pressure source PM as described,
fluid from this source then admitted to the conduit 132 will not open the check
valve 154. Still further, the pressure of the fluid source PL, while lower than the
pressure of the fluid source PH, must be such that on connecting the chuck-open-
ing cylinder end 26 with the fluid pressure source PL via the check valva 154
and valve 126 as described~ the pressure of the fluid then admitted to the chuck-
opening cylinder end, being the pressure of the fluid source PL minus the pressure
--16--
of fluid required to open the check valve 154, must be lower than the pressure
of the fluid source PM for a reason explained hereinafter. Thus, on connecting
the chuck-opening cylinder end 26 and the fluid passage 38 with the fluid press-
ure sources PL and PM, respectively, as described, the pressure of the fluid
acting on the larger face 94 of the plunger 58 is lower than the pressure of the
fluid from the source PM acting on the smaller face 92 of the plunger 58. This is
a prerequisite for achieving, on the one hand, the required opening of the check
valve 56 without venting of the fluid passage 38, and the ensuing release of the
fluid of high pressure in the chuck-closing cylinder end 24 for assimilation with
the fluid of the pressure PM admitted to the passage 38 and astablishment of a
common pressure, i.e., the pressure of the fluid source PM, for all fluid in the ,~
passage 38 and chuck-closing cylinder end 24, and for achieving, on the other
hand, and after the establishment of the common pressure of all fluid in the pass-
age 38 and chuck-closing cylinder end 24, irnperative retention of a positive work
grip by the chuck at any instant. The check valve 56 will be opened under the
conditions just described even though the pressure , i . e ., the specific pressure ,
of the fluid acting on the larger face 94 of the plunger 58 is lower than the press-
ure, i.e., the specific pressure, of the fluid then acting on the smaller face 92
of this plunger, because the effective total pressure of the fluid on the larger
plunger face 94 is indeed greater than the effective total pressure of the fluid on
the smaller plunger face 92 as long as the specific pressures of the fluid on the
smaller and larger plunger faces 92 and 94 are of a ratio smaller than the
ratio of the areas of the larger and smaller plunger faces. For a better understand-
ing of this, let it be assumed that the areas of the plunger faces 94 and 92 be
2 2
an exemplary 5 inch and an exemplary 1 inch at an exemplary area ratio of
5 to 1 of these plunger faces, that the specific pressures of the fkuid sources
PL and PM be 90 and 50 lbs. per inch, respectively, and that the minimum
pressure required to open the chbck valve 154 be 50 lbs. per inch, the spec-
--17--
11;~3~'~3
1 if ic pres sure of the fluid supplied from the source PL and acting on the larger
plung0r face 94 would be 90 minus 50 or 40 lbs. per inch, while the specific
` pressure of the fluid supplied from the source PM and acting on the smaller plun-
ger face 92 would be 50 lbs. per inch . Under these circumstances, the total
pressure of fluid on the larger plunger face 94 would be 40 times 5 lbs. or 200
lbs ., while the total pressure of fluid on the smaller plunger face 92 would be
50 times 1 or 50 lbs., wherefore the total pressure of fluid on the larger plunger
face, being greater than the total pressure of fluid on the smaller plunger face,
would indeed open the check valve 56. Also, the ratio of the specific fluid
10 pressures acting on the smaller and larger plunger faces 92 and 94, being in
this example 50 to 40 or 5 to 4, is indeed smaller than the area ratio of 5 to
of the plunger faces 94 and 92, as is required for opening of the check valve 56
without venting the fluid passage 38.
Connection of the chuck-opening cylinlder end 26 and of the fluid passage
38 with the respective fluid pressure sources PL and PM will bring about establishr
ment of a common pressure, i . e ., that of the fluid source PM, of all fluid in the
passage 38 and chuck-closing cylinder end 24, and this common fluid pressure
corresponds to the hereinbefore explained minimum fluid pressure at which the
chuck will relax its work grip, but which is too low for a safe grip of the work
20 by the chuck for the low stage of its operation. Accordingly, once this comm-
on minimum fluid pressure is established for all fluid in the passage 38 and
chuck-closing cylinder end 24, the work grip of the chuck is increased to
where it is safe for the low stage of the chuck operation. This i~ achieved in
this instance by venting the chuck-opening cylinder end 26 via the fluid passage
46 and vent opening 150 in the valve 126 on deenergizing the relay 158 for
spring-return of the member 160 of tha valve 126 to the position shown, and
connecting the fluid pressure source PL with the chuck-closing cylinder end 24
via conduit 132, valve 124, conduit 138S valve 122 and fluid passage 38, on
--18--
11~3~3
deenergizing relay 170 for syring return of the member 172 of valve 128 to the
position shown, and maintaining the relay 176 energized to keep the member 178
of the valve 124 in its other position against the force of the return spring 180.
The chuck will now resume its operation at the low stage thereof. Once the low
stage of the chuck operation is concluded, the power drive of the chuck is stopp-
ed and the chuck is opened for release of the work therefrom, with opening of the
chuck being achieved by connecting the chuck-opening cylinder end 26 with the
fluid pressure source PL via conduit 132, conduit 146 with the interposed check
valve 154, valve 126 and fluid passage 46 on energizing the relay 158 to shift
the member 160 of valve 126 to its other position against the force of the return
spring 162, and venting the chuck-closing cylinder end 24 via the fluid passage
38 and vent opening 142 in valve 122 on energizing the relay 164 for shifting the
member 166 of valve 122 to its other position against the force of the return
spring 168.
It will be noted that high-low chuck operation by the mechanism 120 with
the cylinder end 24being the designated chuck-closing cylinder end requires
only one stepped plunger, i.e., the plunger 53 associated with the check valve
56 for the designated chuck-closing cylinder end. Of course, by forming the plun-
gers 58 and 72 for both chesk valves as stepped plungers, high-low chuck op-
20 eration by the mechanism with the cylinder end 26 being the designated chuck-
closing cylinder end is accomplished by mere reversal of two connections in the
fluid lines to the cylinder ends, as will be readily understood. The check valve
56 affords the usual safety in operation of the mechanism during the high and
low stages of a high-low chuck operation, in that the operating fluid in the
chuck-closing cylinder end will be trapped therein if the fluid supply thereto
shou~d be interrupted at any time, as by a leak in or rupture of the supply line
to this cylinder end. The other valve 70 will afford the same safety in oper-
ation of the mechanism ii the other end 26 is used as the chuck-closing cylinder
end on reversing two connections in the fluid supply lines to the cylinder enfd.
--19--
~ 3Z~3
Also, while the operating fluid used in the described operation of the mechanism
is air which accounts for the described venting of fluid at the openings 142 and
150 in the valves 122 and 126, it is, of course, entirely feasible to use liquid,
such as oil, for example, as the operating fluid for the mechanism in which case ,'~
the openings 142 and 150 in the valves 122 and 126 are connected with return
lines to a liquid supply or supplies for pumps that may constitute the fluid press-
ure s ource s .
Reference is now had to Fig. 4 which shows diagrammatically chuck-oper-
ating mechanism 200 which also lends itself to high-low operation of an associat-
10 ed chuck, and includes valve mechanism which differs in several respects fromthe valve mechanism in Fig. 3. Thus, while the valve mechanism of Fig. 3
requires the establishment of two different fluid pressures in the chuck-closing
cylinder end for the two functions of relaxing the work grip of the chuck and
subsequently operating the chuck at the low stage of its operation, the valve
mechanism of Fig. 4 requires the establishment of only one fluid pressure in
the chuck-closing cylinder end for the same two functions. Also, while the valve
mechanism of Fig. 3 requires an extra check valve 154, the valve mechanism
of Fig. 4 does not require such an extra check valve. Still further, while
with the valve mechanism of Fig. 3 the chuck is opened with a force which is
20 way below the force with which the chuck is closed for the high stage of its
operation, the valve mechanism of Fig. 4 follows the more usual procedure of
opening the chuck with a force equal to that with which the same is closed.
The valve mechanism of Fig. 4 provides in this instance four separate valves
202,204,206 and 208, and there are available three fluid sources PH,PL and PM
of different pressures, of which "H", "L" and "M" signify "high" pressure,
"low" pressure and "minimum" pressure, respectively. The fluid pressure source
PH is by conduits 210 and 212 connected with inlets 214 and 216 in the valves
202 and 206. The fluid pressure source PL is connected with another inlet 218
--20--
in the valve 202, while the remaining fluid pressure source PM ls connected
; with another i,nlet 220 in the valve 206. The valve 206 also has an outlet 222
which through a conduit 224 is connected with an inlet 226 in the valve 204,
with the ]atter also having a vent passage 228 and an outlet 230 which is conn-
ected to a conduit 34a that extends to a ~luid coupling lOa which may in all res--
pects be like the coupling 10 of Figs . 1 and 2. The conduit 34a connects with
an orifice 42a that extends in the coupling lOa and leads to the chuck-closing
cylinder end 24a of the cylinder 20a in the rotary coupling part 14a, with the
conduit 34a and orifice 42a together defining a fluid passage 38a from the
valve 204 to the chuck-closing cylinder end 24a. The valve 206 has an outlet
232 which through a conduit 234 is connected with an inlet 236 in the valve
208, and the latter also has a vent opening 238 and an outlet 240 to which is
connected a conduit 36a that extends to the fluid coupling lOa. The conduit
16a connects with an orifice 50a which extends in the coupling lOa and
leads to the chuck-opening cylinder end 26a, with the conduit 36a and orifice
50a together defining a fluid passage 46a from the valve 208 to the chuck-opening
cylinder end 26a. Fig. 4 also shows fluid lock units 52a and 54a in associat-
ion with the fluid passages 38a and 46a.
Let it now be assumed that the associated chuck is open, with fluid ~f- .-n
20 from the source PH being then admitted to the chuck-opening cylinder end 26a
via conduit 212, valve 206, conduit 234, valve 208,ar~;fluid passage 46a, on
energizing a relay 242 and ensuing shift of the member 244 of valve 208 to its
other position against the force of the return spring 246, and the chuck-closing
cylinder end 24a being then vented via fluid passage 38a and the vent opening
228 in the valve 204 on energizing a relay 248 and ensuing shift of the member
250 of valve 204 to its other position against the force of the return spring 252.
The hgh stage of the high-low chuck operation may then be started by connect~
ing the chuck-closing cylinder end 24a with the fluid pressure source PH and
simultaneously venting the chuck-opening cylinder end 26a, with the cylinder
end 24a being connected with the fluid pressure source PH via conduit 210,
valve 202, conduit 224, valve 204 and fluid passage 38a on deenergizing relay
248 for spring return of the member 250 of valve 204 to the position shown,
and the other cylinder end 26a being vented via fluid passage 46a and the vent
opening 238 in valve 208 on deenergizing relày 242 and ensuing spring return
of the member 244 of valve 208 to the position shown. At the conclusion of the
high stage of the chuck operation, the mechanism 200 is operated for the low
stage of the chuck operation. To the latter end, the fluid passage 38a and the
chuck-opening cylinder end 26aare connected with the fluid pressure sources PL
and PM, respectively, whereby either connection may be established first. Thus,
10 the fluid passage 38a is connected with the fluid pressure source PL via valve
202, conduit 224 and valve 204 on energizing a relay 260 and ensuing shift of
the member 262 of valve 202 to its other position against the force of the return
spring 264, while the chuck-opening cylinder end 26a is connected with the fluid
pressure source PM via valve 206, conduit 234, valve 208 and fluid passage 46a
on energizing a relay 266 with ensuing shift of the member 268 of valve 206 to
its other position against the force of the return spring 270 and also energizing
the relay 242 for shi~tlng the member 244 of~ valve 208 to its other position
against the force of the return spring 246. With the pressures of the fluid
sources PL and PM being lower than that of the fluid source PH, and with the
20 pressures of these fluid sources PL and P~l~ being, furthermore, of a ratio
smaller than the ratio of the larger and smaller areas of the opposite faces of
the plunger associated with the check valve for the chuck'`~losing cylinder end
24a, the pressure of fluid then acting on the opposite faces of this plunger
compel opening of the associated check valve and assimilation of the fluid
from the source PL admitted to the fluid passage 38a and establishment of a
common pressure, i.e., that of the fluid from the source PL, for all fluid in
the passage 38a and chuck~ closing cylinder end 24a, with ensuing relaxation
of the work grip of the chuck. Once this is accomplished, the work grip of the
chuck is decreased to that required for the low stage of the chuck operation
by simply venting the chuck-opening cylinder~ end 26a via fluid passage 46a
1~;3;~2~3
and the vent opening 238 in valve 208 on deenergizing relay 242 for spring
return of the member 244 to the position shown. The chuck is now set for the
low stage of its operation on resuming the chuck drive. At the conclusion of
the low stage of the chuck operation, the drive of the chuck is stopped and
the chuck is opened as described earlier for release of the work therefrom.
Reference is finally had to Fig. 5 which shows diagrammatically chuck
operating mechanism which also lends itself to high-low operation of an ass-o
ociated chuck, and includes valve mechanism which is modified from those of
Fig .3 and 4. The valve mechanism of Fig .5 provides in this instance only three
valves 280, 282 and 284, and is otherwise further distinguished from the other
valve mechanisms by requiring only two fluid pressure sources PH and PL, of
which "H" and "L" signify "high" pressure and "low" pressure, respectively.
The fluid pressure sources PH and PL are connected to inlets 286 and 288 in the
valve 280 which also has an outlet 290 that is connected through branch con-
duits 292 and 294 with inlets 296 and 298 in the valves 282 and 284. Valve
282 is provided with a vent opening 300 and also with an outlet 302 which is
connected with a conduit ~4b which extends to the sta.ionary part 12b of the
fluid coupling lOb the rotary companion part 14b of which provides a cylinder
20b with its chuck-closing and chuck-opening cylinder ends 24b and 26b. The
conduit 34b connects with an orifice 42b~in the coupling lOb which leads to
the chuck-closing cylinder end 24b, with the conduit 34b and orifice 42b to-
gether defining a fluid passage 38b from t~ valve 282 to the chuck-closing
cylinder end 24b. Interposed in the branch conduit 294 is a check valve 306
which is normally closed by a spring 308 to block fluid flow from the valve
284 to the valve 280. The valve 284 is provided with a vent opening 310 and
an outlet 312 which is connected with a conduit 36b that extends to the coupling
lOb and there connects with an orifice 50b in the coupling which leads to the
cylinder end 26b, with the conduit 36b and orifice 50b defining a passage 46b
from the
--23--
valve 284 to the chuck-opening cylinder end 26b. Also shown diagrammatically c -are the fluid lock units 52b and 54b in association with the fluid passages 38b
and 46b.
Let it now be assumed that the associated chuck is open, with the fluid
pressure source PH being then connected with the chuck-opening cylinder end 26b,and the chuck-closing cylinder end 24b beingvented, with the fluid pressure source ~~
PH being connected with the chuck-opening cylinder end 26b via valve 280, b~nch
conduit 294 with the interposed check valve 306, valve 284 and fluid passage
46b, on energizing a relay 316 and ensuing shift of the member 318 of valve 284
to its other position against the force of a return spring 320, and the chuck-clos~3-~
ing cylinder end 24b being vented vla fluid passage 38b and vent opening 300 in
valve 282 on energizing a relay 322 and ensuing shift of member 324 of valve
282 into its other position against the force of a return spring 326. The high
stage of a high-low chuck operation may then be started by connecting the
fluid pressure source PH with the chuck-closing cylinder end 24b via valve 280,
branch conduit 292, valve 282 and fluid passage 38b, on deenergizing relay
322 and ensuing spring return of the ~ember 324 to the position shown, and
venting the chuck-opening cylinder end 26b via fluid passage 46b and vent op-
ening 310 in valve 284 on deenergizing relay 216 and ensuing spring return of
the member 318 of valve 284 to the position shown. At the conclusion of the
high stage of the chuck operation, the valve mechanism is operated for the low
stage of the chuck operation. To this end, the fluid passage 38b and the chuck-
closing cylinder end 24b are first connected with the fluid pressure source PL,
with the fluid passage 38b being connected with this fluid pressure source via
valve 280, branch conduit 292 and valve 282, on energizing a relay 330 and
ensuing shift of a member 332 of valve 280 to its other position, and the chuck-openingend 26b being connected with the fluid pressure source PL via valve 280,
branch conduit 294 with the interposed check valve 306, valve 284 and fluid
passage 46b, on energizing relay 316 and ensuing shift of the member 31g of
--24--
3~fl3
valve 284 to its other position against the force of the return spring 320. The
pressure of fluid thus admitted to the passage 38b is that of the fluid supply
PL, while the pressure of fluid admitted to the chuck-opening cylinder end 26b
is that of the fluid supply PL minus the pressure of fluid required to open the
check valve 306, with the closing spring 308 of the latter being calibrated so
that the pressures of the fluid admitted to the passage 38b and to the chuck-
opening cylinder end 26b are of a ratio smaller than the ratio of the larger and
smaller faces of the plunger associated with the check valve in the fluid
passage 38b in order that the plunger will open the associated check valve
10 and thereby permit assimilation of the fluid of high pressure in the chuck-clos -.~ c~
ing cylinder end 24b with the fluid admitted to this passage, for all fluid in
the latter and in the chuck-closing cylinder end and thereby cause relaxation
of the work grip by the chuck. Once this is accomplished, the work grip of
the chuck is increased to that prescribed for the low stage of the chuck oper-
ation, by simply venting the chuck-opening cylinder 26b via fluid passage 46b
and vent opening 310 in valve 284 on deenergizing the relay 316 for spring return
of the member 318 of valve 284 to the position shown . The chuck is now set
for the low stage of its operation on resumimg the chuck drive. At the conclus-
ion of the low stage of the chuck operation, the drive of the chuck is stopped
20 and the chuck is opened for release of the work.
:- :
