Adjustable stroke clamp

Information

  • Patent Grant
  • 6612557
  • Patent Number
    6,612,557
  • Date Filed
    Monday, April 30, 2001
    23 years ago
  • Date Issued
    Tuesday, September 2, 2003
    21 years ago
Abstract
An apparatus to position or clamp a work piece includes a body, a generally linearly moving powered actuator positioned in the body, and a mechanism to adjust an available stroke of the actuator. The actuator has a first piston coupled to a second piston. The available stroke is defined by a distance spanned by the first and second pistons.
Description




BACKGROUND AND SUMMARY OF THE INVENTION




The present invention relates generally to clamping and positioning devices and, more particularly, to a powered clamp or positioning mechanism having an adjustable stroke.




Powered clamps are commonly used in industrial applications for holding work pieces of many sizes and shapes during forming and machining operations. Such devices include a pneumatically or hydraulically actuated cylinder which causes one or more arms to move through a desired range of rotational motion to push against a work piece. Depending on the specific application, the user may wish to actuate one or two arms which may be vertically or horizontally aligned in an environment contaminated with weld splatter, saw chips, coolants, dust and dirt. Two such conventionally powered clamps are disclosed in U.S. Pat. No. 5,171,001 entitled “Sealed Power Clamp” and U.S. Pat. No. 5,884,903 entitled “Powered Clamp and Gauging Apparatus”, both of which are hereby incorporated by reference.




When operating a powered clamp or positioning mechanism, it is often desirable to limit the range of motion of the cylinder within a certain operating window.




Various traditionally powered clamps have been modified to provide a method of adjusting the cylinder stroke of the clamp. The most common device includes a screw threadingly engaged with the rear end cap extending into the piston cylinder. The screw position may be adjusted by rotating the screw thereby adjusting the position of a stop for the piston. Unfortunately, several components must be either moved or temporarily removed to perform the adjustment process. Specifically, the proximity sensors must be moved after each adjustment. In addition, several tools are required to complete these steps. The adjustment screws used within the clamp are very long if a full range of stroke is to be accommodated. An increased length of adjustment screw increases the overall lengths of the cylinder which also increases the likelihood of interference and damage to the adjustment screw and piston. Such elongated cylinders also undesirably require extra space in the end use manufacturing plant. If the adjustment screw is shortened, the stroke is correspondingly shortened thereby increasing the number of cylinder models required to provide a certain stroke range.




In accordance with the teachings of the present invention, a preferred embodiment of an adjustable stroke clamp includes a first piston and a second piston interconnected by a threaded fastener arrangement such that the position of the first piston may be adjusted and maintained relative to the position of the second piston. Accordingly, because the length of a piston cylinder is fixed, the stroke of a piston rod may be adjusted by adjusting the relative distance between the two pistons.




Another aspect of the present invention includes an apparatus to position or clamp a work piece having a body, a generally linearly moving powered actuator positioned in the body, and a mechanism to adjust an available stroke of the actuator. The actuator has a first piston coupled to a second piston. The available stroke is defined by a distance spanned by the first and second pistons.




The adjustable stroke clamp and positioning apparatus of the present invention is highly advantageous over conventional clamps because the present invention includes a floating driver to engage the head of a threaded rod. The piston rod, which is internally threaded in combination with the floating driver, allows stroke adjustment with a single allen wrench. In addition, no disassembly whatsoever is required to adjust the stroke of the clamp. Because clamps are often used in highly contaminated environments, it is highly desirable to be able to adjust the stroke of the cylinder without disassembling it.




Another advantage of the present invention is that the pistons themselves carry probe or sensor pins which cooperate with proximity sensors for indicating the position of the pistons within the cylinder. Unlike other devices presently available, the present invention does not require a repositioning of the sensors after a stroke adjustment. Also, less air is required to actuate the clamp when the pistons are spaced apart. A cost operational savings may be realized based on the reduced volume of compressed fluid required.




Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.











BRIEF DESCRIPTION OF THE DRAWINGS




The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:





FIG. 1

is an exploded, perspective view showing the preferred embodiment of an adjustable stroke clamp of the present invention;





FIG. 2

is a cross-sectional side view, taken along line


2





2


of

FIG. 1

, showing the preferred embodiment of the present invention;





FIG. 3

is a cross-sectional side view, like that of

FIG. 2

, showing an actuator of the preferred embodiment clamp, located in a fully retracted position;





FIG. 4

is a cross-sectional side view showing a first piston spaced apart from a second piston of an actuator employed in the preferred embodiment of the present invention clamp;





FIG. 5

is an exploded perspective view of a first embodiment of an actuator employed in the preferred embodiment of the present invention;





FIG. 6

is an exploded view of a second preferred embodiment of an actuator employed in the present invention clamp;





FIG. 7

is a cross-sectional side view showing the second preferred embodiment actuator of the present invention clamp;





FIG. 8

is a partial exploded side view of the preferred embodiment of the present invention clamp;





FIG. 9

is a cross-sectional side view of an alternate embodiment of the present invention clamp; and





FIG. 10

is a cross-sectional end view of the alternate embodiment of the present invention shown in FIG.


9


.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS





FIGS. 1 and 2

show a first preferred embodiment of an adjustable clamp and positioning mechanism


20


constructed in accordance with the teachings of the present invention. Adjustable clamp


20


includes a body or housing


22


, an actuator


24


, a link


28


, a crank


30


, a hub


32


, and an arm


34


. Arm


34


is located external to body


22


while the other aforementioned components are internally disposed within the body. Arm


34


may be reversed to attach to a face of hub


32


on either side of body


22


. Alternatively, a pair of arms may be coupled to both faces of hub


32


.




Body


22


is preferably forged or extruded from 6061-T6 aluminum and then machined as a unitary hollow part. An end cap


36


is fastened upon a proximal end of body


22


while a front cover


38


is threadingly engaged with an open distal end of body


22


. Seals and elastomeric O-rings, or the like, are disposed between end cap


36


, front cover


38


and body


22


. Once each of the internal components of the adjustable clamp have been assembled, a cavity


40


within the distal end of body


22


is filled with lubricant and sealed by front cover


38


. Accordingly, the one piece nature of body


22


aids in achieving a fully sealed and permanently lubricated adjustable clamp assembly.




Actuator


24


includes a first piston


42


, a second piston


44


, an elongated, cylindrical piston rod


46


and a threaded rod


48


. First piston


42


and second piston


44


are linearly translatable within a longitudinally oriented cylinder bore


50


machined in body


22


. Bore


50


has an oval cross-sectional shape to orient each of the pistons within the bore during actuation. Each of the pistons are displaced in response to, preferably pneumatic or alternately, hydraulic fluid pressures forcing the pistons in either longitudinal direction. Various annular and elastomeric seals


52


are provided between portions of actuator


24


and the coincidental bores within body


22


.




Linear translation of actuator


24


is converted to rotational movement of arm


34


through piston rod


46


, pivoting link


28


, crank


30


and hub


32


. The present invention functions to assist a user in setting the total range of hub and arm rotation per actuation. In practice, an operator may adjust the stroke of actuator


24


to obtain the desired range of rotation. One benefit of the present invention is that a stroke adjustment may be made without disassembling adjustable clamp


20


in any manner.




As shown in

FIGS. 3 and 4

, adjustment is accomplished through the use of a driver


54


disposed within an aperture


56


of end cap


36


. Driver


54


is retained in aperture


56


by a snap ring


57


. Driver


54


includes a body portion


58


and a protruding shank portion


60


. An O-ring


61


is positioned between body portion


58


and aperture


56


to provide a seal for driver


54


. Shank portion


60


has a hexagonal cross-section for removable engagement with a recessed socket


62


located in a head


64


of threaded rod


48


. Socket


62


also has a hexagonal cross-sectional shape. It should be appreciated that aperture


56


is sized to allow driver


54


to maintain a complete rotational degree of freedom and a limited translational degree of freedom along an axis


66


extending longitudinally through body


22


. In this manner, actuator


24


may be fully retracted as shown in

FIG. 3

, without concern for alignment between shank portion


60


of driver


54


and socket


62


of threaded rod


48


. When an adjustment is desired, an operator simply engages an externally removable allen wrench


67


with a recessed socket


68


found in body portion


58


of driver


54


. At this time, driver


54


may be rotated and axially displaced to engage shank portion


60


within socket


62


. Because threaded rod


48


is equipped with a right-hand thread, counter-clockwise rotation of driver


54


and threaded rod


48


increases the distance between first piston


42


and second piston


44


thereby reducing the total allowable stroke of actuator


24


.





FIG. 5

illustrates actuator


24


in greater detail. A head or collar


64


of threaded rod


48


is disposed within a circular counter-bore


70


and retained therein via a snap ring


72


. An O-ring


74


provides a seal between head


64


and counter-bore


70


. It should be appreciated that this method of interconnection provides first piston


42


a complete rotational degree of freedom about axis


66


.




First piston


42


has a generally oval cross-sectional shape with a first sensor pin


76


which extends toward end cap


36


. As best shown in

FIG. 4

, first sensor pin


76


is movable to a position within a sensor pin receptacle


78


of end cap


36


when actuator


24


is in its fully retracted position. A proximity switch


80


includes a first probe


82


and a second probe


84


for determining the presence of sensor pins within the sensor pin receptacles. An appropriate signal is output from proximity switch


80


if a sensor pin is detected by the first or second probes. It is noteworthy that the sensor pins and switches are automatically adjusted when the piston spacing is adjusted.




Second piston


44


includes a generally oval cross-sectional shape with a circular counter-bore


86


having a threaded portion


88


. It should be appreciated that while the first and second pistons of the preferred embodiment are shown having an oval cross-sectional shape, the shape is not critical to the function of adjustment clamp


20


. Specifically, it is alternately contemplated that pistons having a circular cross-section be utilized in conjunction with an anti-rotational device.




A proximal end


90


of piston rod


46


includes an external thread for engagement with threaded portion


88


. A seal


92


is positioned between counter-bore


86


and piston rod


46


to prevent fluid from passing thereby. In addition, piston rod


46


includes a generally cylindrical mid-section


94


with a bifurcated distal end


96


. Mid-section


94


also includes an aperture


98


which is at least partially threaded near proximal end


90


for engagement with threaded rod


48


. It should be appreciated that aperture


98


extends at least substantially equal to the length of threaded rod


48


to allow first piston


42


to be positioned adjacent to and in contact with second piston


44


, as shown in FIG.


3


. Threaded rod


48


is also of sufficient length to maintain threaded engagement with aperture


98


when first piston


42


is spaced apart from second piston


44


, a distance approximately equivalent to the length of bore


50


. In operation, an anti-rotational compound such as Vibra-tite brand material, is applied between threaded rod


48


and piston rod


46


to maintain the desired distance spanned by pistons


42


and


44


.




A pair of second sensor pins


100


extend from second piston


44


toward front cover


38


. Because adjustable clamp


20


is capable of fully advancing to a position where actuator


24


is in a self-locking, or “over-center” position, the distance from a stop face


102


of second piston


44


to bifurcated distal end


96


must be closely controlled. Accordingly, when assembling piston rod


46


to second piston


44


, an operator threadingly engages piston rod


46


with threaded portion


88


until the piston rod bottoms within counter-bore


86


. Second piston


44


is backed off from the seated position previously described a minimal amount to align one of second sensor pins


100


with a sensor pin receptacle


104


(see FIG.


4


). Because second piston


44


includes two second sensor pins


100


, alignment may be achieved by rotating the second piston relative to the piston rod a maximum of 180 degrees. If only one second sensor pin were provided, second piston


44


may require rotation of nearly one full turn or 360 degrees relative to piston rod


46


to achieve proper alignment. A variance of one full turn or one full thread pitch in overall length of actuator


24


is undesirable and therefore avoided by the use of two second sensor pins


100


. Additionally, by using this method of attachment, second piston


44


is able to rotate or “float” a small amount relative to bore


50


and piston rod


46


. The floating type connection allows each of the pistons to move slightly within bore


50


to provide an optimized seal with minimal wear.




With reference to

FIGS. 6 and 7

, a second preferred embodiment of the clamp employs a varied actuator


140


. A first piston


142


is identical to a second piston


144


with the exception that first piston


142


includes a first sensor pin


146


which extends toward end cap


36


while second piston


144


includes a second sensor pin


148


which extends toward front cover


38


. Accordingly, only first piston


142


will be described in greater detail.




First piston


142


has a generally oval shape with a first aperture


152


for receipt of first sensor pin


146


and a second aperture


154


for receipt of threaded rod


48


. Second aperture


154


includes a through bore portion


156


and a key hole slot


158


partially extending through first piston


142


. A detent


159


transversely extends through a portion of first piston


142


. Threaded rod


48


is coupled to first piston


142


by displacing collar


64


within the key hole slot


158


and translating threaded rod


48


into detent


159


until the longitudinal axis of the threaded rod aligns with through bore portion


156


. Detent


159


is sized to receive collar


64


and resist axial displacement of threaded rod


48


once the above-described component alignment occurs.




Piston rod


160


includes a proximal end


162


having a collar


164


similarly coupled to second piston


144


. In addition, piston rod


160


has a generally cylindrical body


166


with a bifurcated distal end and aperture substantially identical to piston rod


46


of first embodiment actuator


24


.




The remaining description is applicable to adjustable clamps incorporating either the first or second embodiment actuator. For purposes of clarity, an adjustable stroke clamp equipped with first embodiment actuator


24


will be described.




With reference to

FIGS. 1 and 8

, bifurcated distal end


96


of piston rod


46


is coupled to a first end


168


of link


28


via a pin


170


. A second end


172


of link


28


is coupled to crank


30


by way of another pin


173


.




Crank


30


includes a seat


174


from which a pair of parallel walls


176


extend in a bifurcated manner. A semi-circular recess


178


is positioned along one edge of each of walls


176


. In addition, four orifices


180


transversely extend through seat


174


and are arranged in a generally semi-circular pattern in relation to each other and semi-circular recess


178


. Crank


30


is preferably machined from 6150 HRS material which is hardened and ground to Rc 50-54.




Hub


32


has a cylindrically-shaped peripheral surface


182


partially split by a laterally extending channel


184


. Hub


32


further includes an annular flange


186


outwardly projecting from an outboard face. Peripheral surface


182


of hub


32


is rotatably received within a matching cross-bore


188


extending through side walls of body


22


. Eight circularly oriented apertures


190


are drilled through both faces of hub


32


and the portion of hub


32


adjacent to channel


184


. A central aperture


192


is also drilled through hub


32


. Hub


32


is preferably machined from 4150 HT material.




Arm


34


is affixed to a face of hub


32


via eight dowel pins


194


and a screw


196


. Screw


196


engages a locking nut


198


and sandwiches a hubcap


200


on its opposite end. Semi-circular recess


178


of crank


30


is designed to provide clearance around the shaft of screw


196


. Arm


34


includes a set of apertures


202


arranged in a generally circular pattern with respect to each other. Dowel pins


194


are positioned within apertures


202


and arm


34


is placed in a pre-selected orientation in relation to hub


32


and body


22


. Four dowel pins


194


also retain hub


32


to crank


30


. Hub


32


is preferably constructed from 1045 material.




An operational sequence may be observed with reference to

FIGS. 2-4

. Specifically, with reference to

FIG. 2

, arm


34


is disposed in a locking position wherein a work piece would be firmly held for a highly repeatable and accurate gauging or clamping function. In this position, actuator


24


is fully extended such that stop face


102


bottoms within bore


50


of body


22


. At this time, first end


168


of link


28


is positioned relative to second end


172


in an “over-center” relation. Accordingly, forces exerted on arm


34


in an attempt to rotate hub


32


in a clockwise direction are resisted. In this manner, adjustable clamp


20


maintains the desired position of arm


34


even if a loss of fluid pressure within bore


50


occurs. It should be appreciated that other links which do not obtain an over-center relation may also be used.





FIG. 3

illustrates actuator


24


in a fully retracted position. In this position, first piston


42


is forced into contact with end cap


36


. First sensor pin


76


is disposed within sensor pin receptacle


78


. Proximity switch


80


outputs an appropriate signal regarding the position of actuator


24


. It is at this actuator position where driver


54


may be selectively disposed within socket


62


and rotated to adjust the stroke of actuator


24


. A maximum stroke condition is shown in

FIG. 3

where first piston


42


is positioned adjacent second piston


44


.




With reference to

FIG. 4

, first piston


42


is spaced apart from second piston


44


to provide a decreased stroke and resultant range of arm articulation. By comparing

FIGS. 3 and 4

, it can be observed that the initial position of arm


34


is affected by adjustment of actuator


24


. The initial or fully retracted arm position varies with actuator adjustment but the final or fully extended position of arm


34


remains constant. This occurs because second piston


44


is coupled to piston rod


46


and piston


44


is free to travel until stop face


102


bottoms in bore


50


. Another feature of the present invention relates to the fact that the volume of space within bore


50


located between first piston


42


and second piston


44


is void of pressurized fluid. Therefore, as the total stroke of adjustable clamp


20


is reduced, the volume of fluid required to displace actuator


24


is correspondingly reduced.




An alternate embodiment of adjustable clamp


20


of the present invention is shown in

FIGS. 9 and 10

. In this exemplary embodiment, body


22


includes a longitudinally extending channel


220


interconnecting bore


50


with cavity


40


. The purpose of providing channel


220


is to increase the surface area available for retracting actuator


24


from the fully extended, over center position previously described. By allowing pressurized fluid to enter cavity


40


, the cross-sectional area of piston rod


46


, or any other member attached to an end of the rod, is added to the area of second piston


44


. Therefore, the force available to retract actuator


24


is increased an amount proportionately equivalent to the increase in surface area achieved by adding the area of piston rod


46


. Alternately, a longitudinal bore may be located independent of and spaced away from the piston rod bore in a parallel manner.




While various embodiments of the clamp have been disclosed herein, other aspects also fall within the scope of the present invention. For example, other piston-to-arm coupling mechanisms can be employed which use additional links or cams to convert linear to rotary motion. Moreover, the adjustable stroke feature can equally apply to work piece grippers and part locators. Additionally, an actuator may be separately manufactured and subsequently attached to a housing or mechanism for moving objects. The body can also have a circular-cylindrical external shape. Additionally, the threaded adjustment rod can be replaced by another. The external adjustment tool can alternately be a screwdriver and may even be integrally attached to the clamp, although some of the robust and compact advantages of the present invention may not be fully achieved. While various materials have been disclosed, other materials can be employed.




The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.



Claims
  • 1. An apparatus for interfacing with a work piece, the apparatus comprising:a body; and an actuator linearly moveable in relation to said body, said actuator including a first piston adjustably connected to a second piston, said first and second pistons operably advancing and retracting in response to fluid pressure, wherein a range of movement of said actuator is defined by a position of said first piston relative to said second piston.
  • 2. The apparatus of claim 1 further including a hub coupled to said actuator for pivotable movement in response to linear movement of said actuator.
  • 3. The apparatus of claim 2 further including a piston rod and an adjustment rod, said piston rod connecting said second piston and said hub, said adjustment rod connecting said first piston and said piston rod.
  • 4. The apparatus of claim 3 wherein said adjustment rod is threadingly engaged with said piston rod such that rotation of said adjustment rod varies said position of said first piston relative to said second piston.
  • 5. The apparatus of claim 3 further including a link having a first end and a second end, said first end pivotably coupled to said piston rod, said second end being coupled to said hub.
  • 6. The apparatus of claim 2 further including a workpiece interfacing arm coupled to said hub, said arm being held in a locked position when said actuator is full extended.
  • 7. The apparatus of claim 1 further comprising a threaded adjustment rod rotatably coupled to said first piston.
  • 8. The apparatus of claim 7 wherein said adjustment rod is rotatably coupled to said second piston.
  • 9. A apparatus comprising:a body having a bore; a first piston slidably moveable in said bore; a second piston positioned substantially coaxially to said first piston in said bore; and an adjustable mechanism coupling said first piston and said second piston, said adjustment mechanism being operable to position said first piston a spaced distance relative to said second piston to limit piston stroke travel and to change fluid quantity required within the bore.
  • 10. The apparatus of claim 9 wherein said adjustment mechanism includes a first threaded member coupled to said first piston and a second threaded member coupled to said second piston, whereby rotation of one of said first and second threaded members relative to the other varies said spaced distance and said clamp stroke.
  • 11. The apparatus of claim 10 further including a driver rotatably coupled to said body, said driver being selectively engageable with said first threaded member to vary said clamp stroke.
  • 12. The apparatus of claim 11 further including an end cap enclosing said bore, said driver being rotatably mounted to and retractable entirely into said end cap, wherein said driver is accessible from outside enclosed bore.
  • 13. The apparatus of claim 12 wherein said first piston is rotatably coupled to said first threaded member to allow said first piston to rotate when forming a seal with said bore.
  • 14. The apparatus of claim 13 further including a hub rotatably coupled to said body, said hub drivingly engaged by said second threaded member to rotate in response to linear displacement of said second threaded member.
  • 15. The apparatus of claim 9 further including a position sensor to sense the position of said first piston, said position sensor having a sensing end facing in a direction parallel to plane defined by a leading face of said first piston.
  • 16. The apparatus of claim 15 wherein said position sensor outputs a first signal when said first piston is in a predetermined position.
  • 17. The apparatus of claim 16 wherein said position sensor outputs a second signal when said second piston is in a predetermined position.
  • 18. The apparatus of claim 17 wherein said position sensor is operable to output said first and second signals regardless of said spaced distance between said first and second pistons.
  • 19. The apparatus of claim 18 further including a sensor pin protruding in an elongated manner from said first piston, said sensor pin located in sensing proximity to said position sensor when said first piston is at said predetermined position.
  • 20. An apparatus to position or clamp a work piece, the apparatus comprising:a body; a generally linearly moving power actuator positioned in said body; and a mechanism operable to adjust an available stroke of said actuator, said actuator having a first piston always coupled to a second piston when the pistons are both advanced, said available stroke being defined by a distance spanned by said first and second pistons.
  • 21. The apparatus of claim 20 wherein said mechanism to adjust said available stroke includes a driver selectively engageable with said actuator to vary said distance spanned by said first and second pistons.
  • 22. The apparatus of claim 21 wherein said driver is accessible from a location outside said body.
  • 23. The apparatus of claim 22 wherein said mechanism to adjust said available stroke includes a first member rotatably coupled to said first piston and a second member rotatably coupled to said second piston, said first member threadingly engaged with said second member whereby rotation of one of said first and second members varies said distance spanned by said first and second pistons.
  • 24. The apparatus of claim 20 wherein pneumatic fluid operably powers said pistons.
  • 25. An apparatus comprising:a body having a wall; an actuator slidingly coupled to said body, said actuator being adjustable to define a changeable stroke distance, said actuator operable traveling relative to said body; and a driver rotatable coupled to said body, at least a majority of said driver being substantially located within said wall of said body, said driver being selectively engageable with said actuator to adjust said stroke distance.
  • 26. The apparatus of claim 25 wherein said actuator includes a first piston movably coupled to a second piston, and wherein said stroke distance is defined by a distance spanned by said first piston and second pistons.
  • 27. The apparatus of claim 26 wherein said actuator includes a threaded member coupled to one of said first and second pistons, wherein rotation of said threaded member adjusts said stroke and the pistons always move together.
  • 28. The apparatus of claim 27 wherein said driver is selectively engageable with said threaded member to vary said distance spanned by said first and second pistons.
  • 29. The apparatus of claim 25 wherein said well of said body is an end cap that is removable from the remainder of said body.
  • 30. A work piece engaging apparatus comprising:a piston having an axially extending aperture with a transversely extending detent formed therein; a rod having an annular collar positionable in said detent to interconnect said piston and said rod; and a workpiece engagable member coupled to and operably moving in response to operable movement of said rod.
  • 31. The apparatus of claim 30 further comprising a seal located around an entire periphery of said piston, wherein said aperture is shaped as a key hole inwardly spaced away from said seal.
  • 32. The apparatus of claim 31 wherein said rod is rotatably coupled to said piston.
  • 33. The apparatus of claim 30 wherein said rod is attached to said piston by axially displacing said collar in said axially extending aperture and transversely displacing said collar in said transversely extending detent.
  • 34. The apparatus of claim 9 wherein the pistons advance and retract together.
  • 35. The apparatus of claim 30 wherein said rod is coaxial with said piston.
  • 36. The apparatus of claim 30 further comprising a link at least partially coupling said rod to said workpiece engagable member, the workpiece engagable member being a rotatable clamping arm.
  • 37. An apparatus comprising:a body; a first piston slidably moveable in said body; a second piston slidably moveable in said body; a threaded member having a socket, said threaded member coupling said first piston to said second piston, wherein said threaded member is operable to vary a distance between said first and second pistons to limit piston stroke travel; and a driver rotatably coupled to said body, said driver including a protruding shank selectively engageable with said socket of said threaded member wherein said threaded member rotates in response to rotation of said driver when said driver is in the engaged position.
  • 38. The apparatus of claim 37 wherein said driver includes a socket engageable by a tool located outside said body and wherein said driver rotates in response to rotation of said tool.
  • 39. The apparatus of claim 38 wherein said tool is engageable with said socket of said driver without any disassembly of said apparatus.
  • 40. The apparatus of claim 39 further including a proximity sensor for sensing the location of at least one of said first and second pistons, said proximity sensor operable to sense piston position while mounted at a single location relative to said body regardless of said distance between said first and second pistons.
  • 41. A method of adjusting a stroke of an apparatus having a body with a tool, the apparatus having a first piston adjustably coupled to a second piston, the first and second pistons slidably moveable in the body the method comprising:(a) engaging an adjustment mechanism with the tool external to said body; (b) rotating the tool; (c) adjustably moving the first piton relative to the second piston; and (d) simultaneously moving the first and second pistons when applying sufficient fluid pressure.
  • 42. The method of claim 41 wherein the step of engaging said adjustment mechanism includes a rotating threaded member coupled to one of said first and second pistons wherein rotation of said threaded member varies a distance spanned by the first and second pistons.
  • 43. The method of claim 42 wherein said adjustment mechanism includes a driver spaced apart from said threaded member and wherein the step of engaging said adjustment mechanism with the tool includes engaging a driver with the tool and displacing said driver into engagement with said threaded member.
  • 44. The method of claim 41 further comprising changing fluid volume required in a cylinder of the body by adjustably moving the first piston relative to the second piston.
  • 45. A work piece engaging apparatus comprising:a body having a first cavity and a second cavity; a piston slidably moveable within said first cavity, a rod having a first end slidably moveable within said first cavity and a second end slidably moveable within said second cavity wherein said first end of said rod is coupled to said piston; and a passageway extending through said body interconnecting said first cavity and said cavity to allow a pressurized fluid to substantially act on said piston and at least one of said first and second ends of said rod substantially simultaneously.
  • 46. The apparatus of claim 45 wherein said actuator includes a second piston slidably moveable within said first cavity.
  • 47. The apparatus of claim 45 wherein said body includes a piston rod bore and wherein said passageway is a longitudinally extending channel in communication with said piston rod bore substantially along its entire length.
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Entry
U.S. patent application Ser. No. 09/426,623, Sawdon et al., filed Oct. 26, 1999.
Norgren “GC3 Grippers”, GC Series Grippers, one page. (Believed to have been offered for sale, publically used or published before Apr. 30, 2001).*
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Brochure of Bimba, (prior to Oct. 26, 1999).