US3581625A

US3581625A - Impact cylinder

Info

Publication number: US3581625A
Application number: US806551A
Authority: US
Inventors: Stanley Joseph Michalak
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-03-12
Filing date: 1969-03-12
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01

Abstract

A pneumatic impact cylinder with a piston latch operable to restrain the piston until predetermined pressure develops on the side of the piston associated with generating impact movement, the said latch being operable to release said piston in direct response to the said pressure.

Description

United States Patent [72] Inventor Stanley Joseph Michalak 9231 S. Cedar Drive, West Olive, Mich. 49460 [21] Appl. No. 806,551 [22) Filed Mar. 12, 1969 [45] Patented June 1,1971

[54] IMPACT CYLINDER 5 Claims, 23 Drawing Figs.

52] us. Cl 91/45,

I 92/24, 92/135 [51] Int. Cl FISb 15/26 [50] Field ofSearch 91/45,41,

- [56] References Cited UNITED STATES PATENTS 2,360,535 10/1944 Ashton 91/44 Primary Examiner-Martin P. Schwadron Assistant Examiner- Irwin C. Cohen Attorney-Glenn B. Morse ABSTRACT: A pneumatic impact cylinder with a piston latch operable to restrain the piston until predetermined pressure develops on the side of the piston associated with generating impact movement, the said latch being operable to release said piston in direct response to the said pressure.

INVENTOR ATTORNEY Fig. 3

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PATENTEUJUN 1197:

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Fig/3 Fig.

Stanley J.Micho ATTORNEY PATENTEU JUN H97l 558L625 I35 HIM Fig. 20 i!! F '9- 23 MENTOR Stanley J. Michuluk BY H. 4

ATTORNEY IMPACT CYLINDER BACKGROUND Pneumatic impact cylinders have a wide variety of uses. Essentially, they are fast-acting air cylinders that deliver a hammerlike blow, and they are often used as actuators for small dies and special machinery. It is common practice to design these piston-cylinder assemblies with one end of the cylinder open, so that the impact velocity of the piston is not opposed by a mass of air entrapped ahead of the piston during the course of its movement. This arrangement necessarily eliminates the possibility of an effective pneumatic retracting motion of the piston, which would be very useful in the stripping" movement of a die to which the cylinder mechanism was connected. Quite commonly, a blanking action in which a-hole is punched in sheet metal requires a forcible withdrawal of the punch out of the hole, and this is very difficult to provide in an open end impact cylinder without the use of an auxiliary cylinder for generating the withdrawal action. The application of vacuum in place of impact pressure is normally not sufficient to generate the necessary forces, and also tends to produce a slamming action which is undesirable.

In addition to the problem of pulling the cylinder back after the delivery of the impact blow, the problem associated with the flow of air through relatively small conduits and orifices produces a throttling action which makes it very difficult to generate a high-rspeed piston movement through the use solely of a valve-controlled air admission. Means have been devised in the past for restraining the movement of piston until sufficient piston forces developed 'to overpower the restraint, and permit the piston to proceed on its impact blow. This arrangement thus permits a considerably amount of pressure to develop in the cylinder prior to the release of the piston, so that the piston velocity can be generated by expansion of the compressed air, rather than relying solely on rapid admission of the air into the cylinder. These restraint devices that operates on the principle of a threshold piston force are subject to variations in performance, and do not have the safety factors characteristic of a positive restraint under the direct control of air pressure.

. SUMMARY OF THE INVENTION The present invention provides a release action generated directly by the pressure within the cylinder, which will ultimately be used to at least assist in inducing the impact motion of the piston. In the preferred form of the invention, a heavy spring is also utilized to produce this movement, the spring being compressed by pressure on the opposite side of the piston. The release of the latch is induced by the movement of a small latch piston which is maintained in locking position by the action of a special spring. The adjustment of this spring establishes the threshold pressure at which the latch operates to retract a group of detents normally in engagement with a shoulder on an inside surface of the main impact piston. The generation of theradial detent movement from locking to released positions is produced by the axial movement of the latch piston in cooperation with the interengagement of inclined surfaces on these members, thus converting the axial movement of the piston to radial movement of the detent elements. In the preferred form of the invention, the pressure which induces the withdrawals of the detents will also control a valve on the opposite side of the main piston to move it to full exhaust position, in order to minimize the resistance ahead of the main piston during its impact motion.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of an impact cylinder embodying the present invention.

FIG. 2 is a sectional elevation along the axis of the cylinder assembly shown in FIG. I, in the extended position of the piston rod.

FIG. 3 is a sectional elevation similar to FIG. 2, with piston rod retracted.

FIG. 4 is an axial section on an enlarged scale showing the piston latch in the retracted condition. FIG. 5 is a section similar to FIG. 4, with the piston latch in locking position.

FIG. 6 is a perspective view of the latch piston.

FIG. 7 is a perspective view of the detent assembly associated with FIGS. 4 and 5.

FIG. 8 is a section on the'plane 8-8 of FIG. 2.

FIG. 9 is a section on the plane 9-9 ofFIG. 3.

FIG. 10 is a section on the plane 10-10 of FIG. 2.

FIG. 11 is an end view of the cylinder illustrated in FIG. I.

FIGI 12 is a perspective view of the control piston shown in FIG. 10. I

FIG. 13 is an end view of the control piston shown in FIG. 12.

FIG. I4 is a section on the plane 14-14 of FIG. 12.

FIG. 15 is an axial section of a modified form of the invention, with the main piston in position to project the piston rod.

FIG. 16 is a section similar to that of FIG. 15, with the piston at the opposite extreme of travel, corresponding to a retraction of the piston rod;

FIG. 17 is a perspective view of the stem of the piston latch v assembly.

FIG. 18 is a perspectiveview of the latch piston associated with the FIG. 15 assembly, 7

FIG. 19 is a perspective view of the detents associated with the FIG. 15 assembly.

FIG. 20 is a perspective view, partially in section, showing the cup unit of the FIG. 15 piston latch assembly.

FIG. 21 is a perspective view, partially in section, of the adjusting cap of the FIG. l5.assembly.

FIG. 22 is a perspective view ofthe rotary valve plate.

FIG. 23 is a perspective view of the cylinder head adjacent the valve plate in the FIG. 15 assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The impact cylinder assembly illustrated in FIGS. 1 through 14 includes the cylinder heads and 31 interconnected by the cylinder sleeve 32, with the heads being secured together by the rods 3336. Each of these rods traverses the heads, and is secured by nuts as shown at 3744. A piston rod traverses the head 30, and the extreme end of this piston rod will normally be connected to the moving section of a die, or some other actuated machine component. The forces delivered by the piston rod will include the inertia effect of the piston 46, together with the effect of air pressure within the chamber 47 defined by the sleeve 32 on the right side of the piston, as shown in FIG. 2, and also the force of the spring 48. The inertia effect of the piston 46 (together with that of the rod 45) will be due to an impact velocity generated by the combined effect of the air pressure and the compression spring 48. This spring moves from the compressed condition shown in FIG. 3 to the extended condition of FIG. 2 in delivering the impact motion. To provide an appropriate spring length, the spring is received within a cylindrical recess 49 in the piston 46, and it ispreferable that the recess be of sufficiently small diameter to leave a considerable wall thickness for the piston to increase its mass, and therefore increase its inertia effect.

The control of the impact cylinder shown in the drawings is accomplished by the selective admission of air pressure through either the port 50 or the port 51. These parts lead into a crossbore in the head 30 which defines a control cylinder 52 carrying the control piston 53. A slot 54 in the side of this piston receives the actuating pin 55 of the valve ring 56. This ring is rotatably received within a suitable recess in the head 30, and is held in place by the retaining ring 57, as best shown in FIG. 3. The pin 55 extends through a passage 58 communicating between the control cylinder 52 and the recess receiving the ring 56. When air is admitted through the port 50, the control piston 53 moves to the position of FIGS. 8 and 10, carrying with it the pin 55. This action rotates the ring 56 into a position such that the holes 5963 are in alignment with the holes 64-68 in the head. This action serves to instantly provide exhaust passages for air within the cylinder defined by the sleeve 32 to the left of the main piston 46.

The external air connections to the unit are preferably arranged so that the admission of air at the port 50 is simultaneous with the admission of air pressure to the port 69 at the opposite end of the cylinder assembly. This results in the development of air pressure within the recess 49 in the main piston, which is communicated through the opening 70 in the base of the cup 71 to the chamber 72 defined by the interior of this cup. As this pressure develops, it reaches a level sufficient to drive the latch piston 73 to the right against the action of the latch spring 74, as air is vented out through the passage 75 in the head 31. The movement of the latch piston 73 to the right brings the conical flange 76 into engagement with the conical inner portions 7780 of the detent elements 8184. (Refer to FIG. 7.) The radial sections 85-88 of these elements extend through appropriately located openings in the wall of the cup 71 in sliding relationship, and movement of the control piston 73 from the FIG. 3 to the FIG. 2 position will result in radially retracting the portions 8588 as a result of the interengagement of the conical flange 76 with the portions 7780. The outer extremities of the portions 8588 are disposed to engage the shoulder 89 formed by the groove 90 in the wall defining the recess 49 of the main piston. Withdrawal of the detents from this groove will release the piston 46 for movement to the left under the combined etfect of the spring 48 and the air pressure in the chamber 47. The opposite side of the piston has been prepared for this movement by the placement of the valve ring 56 in the exhaust position, as previously described.

Since it is desirable to obtain as much assistance from the air pressure as possible, the spring 74 functions primarily to establish a predetermined intensity of the chamber pressure back of the piston before the latch system releases the piston. The amount of this release pressure is determined by adjustment of the screw 91, the inner extremity of which serves as a seat for the spring 74. The stem 92 is slidable within the interior of the screw 91, with the latter being in threaded engagement with the head 31. A retaining ring 93 secures the stem against outward movement as a result of air pressure, as the cup 71 is fixed through threaded engagement with the head 31. The hollow interior of the stem 92 provides an air passage into the chamber 47 and the piston recess 49. To prevent leakage, the interior of the latch piston 73 is sealed around the stem 92 by the O-ring 94, and passage out around the periphery of the stem 92 through the bolt 91 is sealed by the "O"-ring 95. The periphery of the latch piston as it engages the cup 71 is sealed by the -ring 96.

In order to prepare the cylinder assembly for the piston release and the resultant impact blow, pressure is admitted to the port 51 rather than the port 50. In other words, the pressure delivered to the port 51 is considerably in excess of that at the port 50. Under these conditions, the control piston 53 is moved to the FIG. 9 position, carrying the actuating pin 55 with it. This action rotates the valve ring to a position in which the holes 59-63 are out of registry with the holes 64-68, and the hole 97 assumes a position opposite the passage 58 communicating with the control cylinder 52. In this position, the lateral hole 98 in the control piston 53 is also in alignment with the passage 58, and the hole 98 communicates with the axial hole 99. A complete passage is thereby created which permits the air pressure to be delivered through the port 51 to the interior of the main cylinder on the left side of the piston 46, as shown in FIGS. 2 and 3. This pressure is delivered in sufficient intensity to compress the main spring 48, and drive the piston to the FIG. 3 position. Conventional O"-ring seals at 100 and 101 are provided to inhibit leakage around the main piston 46. The piston rod 45 is carried with the piston during this movement through the action of the retaining ring 102. As this movement continues to its extreme point shown in FIG. 3, the edge defining the opening of the cylindrical recess 49 encounters the peripheral bevelled edges 103-106 of the detent elements and forces them inwardly against the effect of the latch mechanism, which had projected them to the FIG. 3 position. This projection is induced by the movement of the latch piston 73 to the left by the latch spring 74, which brings the conical surface 107 in engagement with the inside surfaces of the portions 7780 of the detent elements, sliding them outwardly. As the piston movement continues to its full extreme, the detent elements move into the groove 89, as shown in FIG. 3. The unit is now ready for a reversal of air pressure to generate the action described previously, which will result in movement from the FIG. 3 to the FIG. 2 position with a rapid impact blow.

The modified form of the invention shown in FIGS. 15 and 16 operates on the same general principles, but with some variations in structural detail. The piston rod 107 traverses the head 108, and is connected to the piston 109. A control piston 110 moves within a control cylinder 111 in the head 108, in the manner previously described. Admission of relatively high-pressure to the conduit 112 results in releasing the piston latch, and in placing the valve ring 113 in the exhaust position. This ring is identical to the ring 56 shown in FIG. 22. The arrangement of ports and openings in the head 108 and in the ring are the same as described in connection with the previous modification. The T"-fitting 114 serves the function of distributing the air pressure from the conduit 112 to the interior of the stem 115 and to the conduit extension 116, which conducts the air pressure to the right side of the control cylinder 111, as shown in FIGS. 15 and 16. In the cylindrical assembly shown in FIGS. 15 and 16, the heads are in threaded engagement with the cylinder sleeve 117 with a modified form of the retaining ring being shown at 118 to hold the valve ring 113 in position. The valve ring is also rotatable with respect to the head 108, as previously described.

The principal difference between the modification shown in FIGS. 15 and 16 and that shown in FIGS. 2 and 3 is in the latch mechanism. The stem 119 is in threaded engagement with the cylinder head 120, and the enlarged end 121 of the stem retains an otherwise free cup 122. The

radial portions

123 and 124 of the

semiannular detents

125 and 126 are interposed axially, between the end of the cup 122 and the inner end of the cylinder head 120. The outermost edges of the

detents

125 and 126 are defined by a circumscribed diameter equal to or slightly less than the diameter of the cup 122. The

conical portions

127 and 128 of the

detents

125 and 126, respectively, are received within the conical slot 129 of the latch piston 130, thus inducing radial extension and retraction according to the movement of the piston along the latch cylinder 131 in the head 120. The upper portion of the cylinder 131 is vented at 132 to permit movement of the piston against the action of the spring 133. The hollow interior of the stem 115 admits pressure in the chamber 134, and the action of the projected

radial sections

123 and 124 is as described in connection with FIGS. 2 and 3. A port is provided at 135 in the cup 122 to assure immediate transmission of air pressure between the main cylinder and the interior of the cup 122. The

detents

125 and 126 engage the shoulder provided by the groove 136 in the same manner as previously described, thus retaining the main piston 109 against the action of the spring 137.

Adjustment of the release pressure is accomplished by manipulation of the special nut 138, which is in threaded engagement with the stem 119. The adjusted position of the nut is maintained by the setscrew 139, and rotation of the nut with respect to the stern will move the

pins

140 and 141, which traverse the head 120 and support the washer 142 acting as a seat for the spring 133. The stem 119 can either be in threaded engagement with the head 120, and locked in place by the nut 143, or the hold in the head 120 receiving the stem 119 may be large enough to clear the threads. The presence of the nut 143 will serve to secure the stem in either case.

The particular embodiments of the present invention which have been illustrated and described herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire invention disclosed herein, except as I am limited by the prior art.

I claim:

l. A pneumatic actuator having a cylinder, a piston received for reciprocation within the cylinder, a piston rod connected to said piston and traversing one end of said cylinder, wherein the improvement comprises:

said piston having an axial pressure responsive surface receiving a main spring;

latch means adapted to interengage said piston to a member normally fixed with respect to said cylinder, said latch means being directly responsive to gas pressure admitted to the pressure responsive surface side of said piston to release said piston for movement in a selected direction;

valve means operatively associated with the said cylinder to selectively admit pressure and provide exhaust on opposite sides of said piston; and

pneumatic conduit means providing pressure to said valve means. 7 v

2, An actuator as defined in claim 1, wherein said pressure responsive surface is defined by an axial recess, and said latch means engages said piston at the surface defining said recess.

3. An actuator as defined in claim 2, wherein said piston has a shoulder on the said recess, and said latch means includes:

a cup normally fixed with respect to said cylinder, and axially receivable in said piston recess, said cup having at least one opening in the periphery thereof;

a detent having a portion traversing said cup opening for reciprocation therein in a direction having a radial component to releaseably engage said shoulder, said detent also having a portion within said cup inclined to the axis thereof;

a latch piston mounted for reciprocation in said cup, and

having axially spaced portions slideably receiving said detent inclined portions;

latch biasing means urging said latch piston in a direction to project said detent means to engaging position, said cup having port means admitting the surrounding pressure in said cylinder to the side of said latch piston corresponding to movement thereof to move said detent to release position against the action of said latch biasing means; and

vent means in said cylinder for releasing pressure on the opposite side of said latch piston.

4. An actuator as defined in claim 1, wherein said valve means includes:

a ring rotatably mounted in the opposite end of said cylinder from said latch means, said ring having at least one opening therein, said cylinder having an exhaust passage in alignment with said opening in a selected angular position of said ring;

means in said opposite cylinder end defining a control cylinder, and a passage extending therefrom to said ring, said ring having an actuating member traversing said passage; and

a control piston slideably mounted in said control cylinder,

said control piston being interengaged with said ring projection whereby reciprocation of said piston induces reciprocating rotary movement of said ring between said selected angular position and a position in which an opening in said ring is disposed in alignment with means forming an intake passage communicating with said cylinder.

5. An actuator as defined in claim 4, wherein said intake passage includes said control cylinder on one side of said control piston.

Claims

1. A pneumatic actuator having a cylinder, a piston received for reciprocation within the cylinder, a piston rod connected to said piston and traversing one end of said cylinder, wherein the improvement comprises: said piston having an axial pressure responsive surface receiving a main spring; latch means adapted to interengage said piston to a member normally fixed with respect to said cylinder, said latch means being directly responsive to gas pressure admitted to the pressure responsive surface side of said piston to release said piston for movement in a selected direction; valve means operatively associated with the said cylinder to selectively admit pressure and provide exhaust on opposite sides of said piston; and pneumatic conduit means providing pressure to said valve means.

2. An actuator as defined in claim 1, wherein said pressure responsive surface is defined by an axial recess, and said latch means engages said piston at the surface defining said recess.

3. An actuator as defined in claim 2, wherein said piston has a shoulder on the said recess, and said latch means includes: a cup normally fixed with respect to said cylinder, and axially receivable in said piston recess, said cup having at least one opening in the periphery thereof; a detent having a portion traversing said cup opening for reciprocation therein in a direction having a radial component to releaseably engage said shoulder, said detent also having a portion within said cup inclined to the axis thereof; a latch piston mounted for reciprocation in said cup, and having axially spaced portions slideably receiving said detent inclined portions; latch biasing means urging said latch piston in a direction to project said detent means to engaging position, said cup having port means admitting the surrounding pressure in said cylinder to the side of said latch piston corresponding to movement thereof to move said detent to release position against the action of said latch biasing means; and vent means in said cylinder for releasing prEssure on the opposite side of said latch piston.

4. An actuator as defined in claim 1, wherein said valve means includes: a ring rotatably mounted in the opposite end of said cylinder from said latch means, said ring having at least one opening therein, said cylinder having an exhaust passage in alignment with said opening in a selected angular position of said ring; means in said opposite cylinder end defining a control cylinder, and a passage extending therefrom to said ring, said ring having an actuating member traversing said passage; and a control piston slideably mounted in said control cylinder, said control piston being interengaged with said ring projection whereby reciprocation of said piston induces reciprocating rotary movement of said ring between said selected angular position and a position in which an opening in said ring is disposed in alignment with means forming an intake passage communicating with said cylinder.