CA2238139C - Load detection and monitoring apparatus - Google Patents

Abstract

A load detection device for monitoring the engagement force between a tool and a workpiece, comprises means having a free end for transmitting a force, the force being transmitted at the free end. A load cell has one face juxtaposed that free end of the means for transmitting a force, for monitoring the force of that force-transmitting means. Biasing means is mounted between the free end and that one face of the load cell, the biasing means providing a biasing force to urge the load cell monitoring the force away from that free end. A piston rod adapter is provided, having a blind bore at one end and an open end opposite that one end; the opposite end being slidably mounted to the free end of the means for transmitting a force. The biasing means and the load cell are mounted in the blind bore of the piston rod adapter, and are interposed between the free end and the bottom of the blind bore. Means for limiting the movement of the means for transmitting a force relative to the piston rod adapter are included; the limiting means being mounted to the means for transmitting a force such that the force transmitted at the free end of the means for transmitting a force is counteracted by the biasing means, and the net effect of the force is monitored by the load cell to determine the engagement force between the tool and the workpiece.

Description

Load Detection And Monitoring Apparatus The present invention relates to a fluid powered apparatus that has application for clamping, punching, welding and other functions that are necessary in the manufacture and assembly of machines and vehicles such as automobiles.
More particularly, the invention is related to a dual action fluid powered apparatus designed to implement a rapid movement in approaching a workpiece until contact is effected. The movement of the apparatus upon contact with the workpiece is then transformed to a slow, more powerful working mode. Specifically, this invention is a device for detecting and monitoring the engagement force between the apparatus and a workpiece, and this application is divided from application 2,025,641, filed September 18, 1990.

The prior art reveals a wide variety of fluid powered devices that employ a plurality of cylinder and piston combinations to control the speed and force of the device as an element thereof advances toward a workpiece.

In general, most of the prior art devices utilize a tandem arrangement for the various pistons that are all contained within a single cylindrical housing.

By way of example, the present invention differs from the oleopneumatic jack that is shown and described in U.S.
Patent No. 3,426,530 entitled "Oleopneumatic Jack with Staged Structure" issued February 11, 1969, to Alexander Georgelin. The jack has a cylindrical tubular body structure with end caps attached thereto. A first piston is positioned at one end within the cylindrical body. The piston has attached thereto an elongated hollow plunger that is adapted to move with the piston. A floating piston is positioned so that it slides freely along the previously mentioned hollow plunger. A third piston is positioned near the other end of the cylindrical body. The third piston has coupled thereto, as an integral part, a thrust member that protrudes from the other end of the cylindrical body. The third piston contains a hollow central chamber into which extends a portion of a thrust member. Air pressure is applied to one end of the floating piston thus causing it to urge oil against the third piston which in turn causes the thrust member attached to the third piston to extend from the cylindrical body. After the initial rapid advancement of the third piston and the thrust member, air pressure is introduced behind the first piston.
As the first piston moves axially along the interior of the cylindrical body, its attached hollow plunger enters the oil filled hollow central chamber of the third piston thus ~0 causing it to move slowly while exerting a large force.

In U.S. Patent No. 4,099,436 entitled "Apparatus for Piercing Sheet Material" issued July ll, 1978, to Donald Beneteau, there is described a force intensifier that employs an oil reservoir that is external of a cylindrical structure that contains a pair of pistons in axial alignment. The oil in the reservoir is forced into the cylinder by pressurized air that is in direct contact with the oil. The oil that is introduced into the cylinder moves one of the pistons, causing a tool carrying plunger to advance toward a workpiece. In order to intensify the force delivered by the tool carrying plunger, air is introduced behind the other piston, causing it to move an attached plunger into a constricted cavity where the oil pressure is greatly increased, thereby exerting an even greater force on the tool carrying plunger.

An additional load producing cylinder is shown in Figure 3 of U.S. Patent No. 4,395,027 entitled "Pressure Intensifying Device" issued July 26, 1983, to Robert Nordmeyer. Figure 3 of the above referenced patent depicts a cross-sectional view of a pressure intensifying device that has an essentially cylindrical configuration. There is a first piston and plunger combination that moves in the direction towards a second piston plunger combination. The first piston moves under the influence of air pressure and returns to its original position by the biasing action of a compression spring. The second piston is essentially hollow and is filled with oil that supplies the force that causes the second piston and plunger to move linearly.
After the second piston has accomplished its initial movement, the first piston plunger is advanced into the oil filled chamber of the second piston. The force on the second piston is thus intensified. The cylinder contains an internally positioned oil reservoir through which the first piston plunger passes. The just mentioned device utilizes, in tandem, pistons that move in the same direction during the initial or advancement movement. One of the inherent drawbacks of the just described device is its overall length. Then, too, the spring that is biased against the first piston subtracts from the overall load that is applied by air pressure.

The apparatus of this invention does not have an air-oil interface since the oil is self-contained completely within the confinement of the apparatus. In addition, the invention has a plunger unit that is separable from the load enhancement plunger.

The apparatus with which this invention is associated does not utilize springs to aid in the movement of the pistons.
Also, the invention is not arranged in a continuous linear array as is the device described in U.S. Patent 4,395,027.

The present invention relates to a load intensifier apparatus for use in any application where a linear force of considerable magnitude is required such as in metal shaping, punching, clamping, and welding. The invention provides a load measuring device for such an oleopneumatic load intensifier apparatus which causes a rapid advance of a tool carrying piston rod followed by slow advance of the piston rod at an increased load. The oleopneumatic apparatus has a master cylinder and an actuating cylinder that can assume different positions with respect to the master cylinder while maintaining fluid communication therewith. An enclosed hydraulic system is shared by the master and actuating cylinders. Pneumatic pressure actuates a piston within the master cylinder that causes a rapid advancement of a hydraulic fed piston within the actuating cylinder, causing a piston rod and a tool associated therewith to contact a workpiece. The load measuring device monitors the load associated with the pneumatic pressure applied to the piston and associated piston rod, located in the master cylinder, and the resultant force applied to the hydraulic fed piston located within the actuating cylinder, to precisely determine the load delivered to the workpiece.

The apparatus of the invention includes a two part housing wherein the second portion of the housing can be arranged at any attitude with respect to the first portion of the housing. The first portion of the housing contains an enclosed oil reservoir that is in communication with the second housing. The first portion of the housing contains a floating piston that moves along the piston rod of an intensifier piston. The second portion of the housing contains a piston and a piston rod that extends from the housing. In the first housing, air pressure is introduced to one side of the floating piston causing a volume of oil located on the other side of the floating piston to move into the second portion of the housing where its pressure causes the piston within the second portion of the housing to undergo rapid movement to advance the attached piston rod toward a workpiece. After the rapid movement of the piston in the second portion of the housing has occurred, the pressure intensifier piston within the first portion of the housing is moved under the influence of air pressure.
The end of the piston rod of the intensifier piston then enters a constricted oil passageway causing a slow but intense movement of the piston in the second portion of the housing. The further movement of the piston in the second portion of the housing causes its piston rod to additionally bias itself against the workpiece.

In one aspect, the invention provides an apparatus for intensifying a force that is applied to a tool to move said tool into and out of engagement with a workpiece. The apparatus comprises a master cylinder having a first manifold, a second manifold adjacent the first manifold, and a third manifold spaced relative those first and second manifolds. The first, second and third manifolds each have at least one aperture therein, and are axially aligned and in spaced apart relationship to one another. Means form a first cavity between the first and second manifolds, and means form a second cavity between the second and third manifolds. An intensifier piston is positioned in the first cavity, the intensifier piston defining first and second chambers in that first cavity. A reservoir piston is positioned in the second cavity, the reservoir piston defining third and fourth chambers in that second cavity.
That reservoir piston has a central bore therein, and an intensifier rod is coupled to the intensifier piston, the intensifier rod passing through an aperture in the second manifold and the central bore of the reservoir piston. An actuating cylinder is positioned in juxtaposed relationship with respect to the master cylinder. Means form a third cavity within the actuating cylinder; a piston is positioned in the third cavity of the actuating cylinder, that piston defining fifth and sixth chambers on each side of the piston. The third chamber adjacent the reservoir piston and the sixth chamber adjacent that piston each contain hydraulic fluid. Passage means can place the third and sixth chambers in fluid communication with each other, that passage means communicating with the second and third manifold at one end and having an opposite end attached to the actuating cylinder. A piston rod is attached to the piston, the piston rod having a free end cantilevered from the actuating cylinder. Means are provided for introducing pressurized pneumatic fluid to the fourth chamber adjacent the reservoir piston, to cause the reservoir piston to force hydraulic fluid from the reservoir piston third chamber into the actuating cylinder sixth chamber that is adjacent to that piston, such that the piston and attached piston rod advance at a first predetermined rate toward a workpiece. Means can introduce pressurized pneumatic fluid to the first chamber adjacent the intensifier piston, to cause the intensifier piston to move and further to move the coupled intensifier rod into one end of the passage means and act on the hydraulic fluid in the sixth chamber such that the pressure of the hydraulic fluid is intensified for introduction to the actuating cylinder sixth chamber that is adjacent that piston to cause the piston rod attached to the piston to advance at a second predetermined rate toward the workpiece.
By another aspect the invention provides an apparatus for intensifying a force that is applied to a tool to move said tool into and out of engagement with a workpiece. The apparatus includes a master cylinder having a first manifold, a second manifold adjacent the first manifold, and a third manifold spaced relative to those first and second manifolds. The first, second and third manifolds each have at least one aperture therein, and are axially aligned and in spaced apart relationship to one another.
Means form a first cavity between the first and second manifolds, and means form a second cavity between the second and third manifolds. An intensifier piston is positioned in the first cavity, that intensifier piston defining first and second chambers in the first cavity. ~A
reservoir piston is positioned in the second cavity, the reservoir piston defining third and fourth chambers in that second cavity, and the reservoir piston has a central bore therein. An intensifier rod is coupled to the intensifier piston, and passes through the at least one aperture in the second manifold and the central bore of the reservoir piston. An actuating cylinder is positioned in spaced relationship with respect to the master cylinder. Means form a third cavity within the actuating cylinder, and a piston is positioned in that third cavity of the actuating cylinder. That piston defines fifth and sixth chambers on each side of the piston. The fourth chamber adjacent the reservoir piston and the sixth chamber adjacent the piston each contain hydraulic fluid. Passage means can place the fourth and sixth ehambers in fluid communication with each other; the passage means having one end juxtaposed the master cylinder and an opposite end attached to the aetuating eylinder. A piston rod is attached to the piston, the piston rod having a free end cantilevered from the actuating eylinder. Means are loeated in the seeond manifold for introducing pressurized fluid to the third chamber adjacent the reservoir piston, to cause the reservoir piston to force hydraulic fluid from the reservoir piston fourth chamber into the actuating cylinder sixth chamber that is adjacent to that piston, such that the piston and the attached piston rod advance at a first predetermined rate toward a workpiece. The means for introducing pressurized fluid to the third chamber comprises at least one port passage complementary with the one of the at least one apertures of the second manifold, to provide ingress of pneumatic fluid to pressurize the third chamber adjacent the reservoir piston, and means for introducing pressurized pneumatic fluid to the first chamber adjacent the intensifier piston to cause the intensifier piston to move and further to move the coupled intensifier rod into the at least one aperture of the third manifold to act on the hydraulic fluid therein such that it is intensified for introduction to the actuating cylinder sixth chamber, to cause the piston rod attached to the piston to advance at a second predetermined rate toward the workpiece.

In accordance with this invention a load detection device, for monitoring the engagement force between a tool and a workpiece, comprises means having a free end for transmitting a force, the force being transmitted at the free end. A load cell has one face juxtaposed that free end of the means for transmitting a force, for monitoring the force of that force-transmitting means. Biasing means is mounted between the free end and that one face of the load cell, the biasing means providing a biasing force to urge the load cell monitoring the force away from that free end. A piston rod adapter is provided, having a blind bore at one end and an open end opposite that one end; the opposite end being slidably mounted to the free end of the means for transmitting a force. The biasing means and the load cell are mounted in the blind bore of the piston rod adapter, and are interposed between the free end and the bottom of the blind bore. Means for limiting the movement of the means for transmitting a force relative to the piston rod adapter are included; the limiting means being mounted to the means for transmitting a force such that the force transmitted at the free end of the means for transmitting a force is counteracted by the biasing means, and the net effect of the force is monitored by the load cell to determine the engagement force between the tool and the workpiece.

The invention also provides a load detection device for monitoring a tool when engaging and disengaging a workpiece. The load detection device comprises a piston rod having a free end, the piston rod transmitting a force at the free end, and having a diametral aperture located adjacent the free end. A load cell is located adjacent the free end of the piston rod. A spring is interposed between the free end and the load cell, the spring biasing the load cell away from the free end, and transmitting the force between the piston rod and the load cell. A piston rod adapter is slidably telescoped over the free end of the piston rod, and encloses the load cell and the spring. The piston rod adapter has a pair of diametrally-opposed longitudinal slots disposed thereon, and a radially-aligned bore for egress of an electrical connection to the load cell. A pin simultaneously engages the diametral aperture of the piston rod and the pair of diametrally-opposed longitudinal slots of the piston rod adapter; the pin retaining the piston rod adapter of the piston rod. The pin is capable of traversing the pair of diametrally-opposed longitudinal slots for providing axial movement ofthe piston rod adapter in relation to the piston rod.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:-Figure 1 is a perspective view that shows a preferred embodiment of the force intensifier of the present invention;

Figure 2 is a top view of the preferred embodiment of Figurel;

Figure 3 is a cross-sectional view taken along section line 3-3 of Figure 2 showing the cylinders and pistons and their interrelationship to one another;

Figure 4, with Figure 1, is a part sectional view of the preferred embodiment of Figure 1 as mounted to a mounting bracket;

Figure 5, with Figure 1, is a cross-sectional view showing the intensifier cap seal arrangement depicted in circle 5 of Figure 3;

Figure 6, with Figure 1, is a cross-sectional view showing the positions of the 0-ring and backup ring arrangement of the actuating cylinder detailed in circle 6 of Figure 3;

Figure 7, with Figure 1, shows an alternative embodiment with the actuating cylinder in fluidic communication with the master cylinder by an external fluid connection to the end cap;

Figure 8A is a cross-sectional view that shows the position of the pistons and piston rods in the fully retracted position;

Figure 8B is a cross-sectional view that shows the position of the pistons and piston rods after pressure has been applied to the reservoir piston;

Figure 8C is a cross-sectional view similar to that shown in Figures 8A and 8B except that intensification has occurred;

Figure 8D is a legend to the fluid pressures indicated in Figures 8A through 8C and Figures 13A and 13D;

Figure 9 is a part sectional view of an embodiment that employs a load cell near the end of the working piston rod;

Figure 10 shows an alternate mounting arrangement with the actuating cylinder directly mounted to the master cylinder auxiliary port;

Figure 11 is a schematic view that shows the valving system utilized with the present apparatus;

Figure 12 is a cross-sectional view of a second embodiment of the invention showing the cylinders and pistons and their interrelationship to one another;

Figure 13A is a cross-sectional view of the second embodi-ment that shows the position of the pistons and piston rods in the fully retracted position;

Figure 13B is a cross-sectional view similar to that shown in Figure 13A showing the position of the pistons and piston rods after pressure has been applied to the retract piston;

Figure 13C is a cross-sectional view similar to that shown o in Figure 13A and 13B showing the position of the pistons and piston rods after pressure has been applied to the reservoir piston; and Figure 13D is a cross-sectional view similar to that shown in Figures 13A, 13B and 13C except that intensification has occurred; and Figure 14 depicts yet a further embodiment of the invention wherein the actuating cylinder can be arranged to have any attitude with respect to the master cylinder.

Referring now to the drawings and more particularly to Figure 1, there is illustrated in perspective one configura-tion of the present load intensification apparatus. The overall apparatus is identified by the numeral 10. The overall apparatus 10 has two distinct subassemblies or housings which shall hereinafter be identified as the master cylinder 12 and the actuating cylinder 14. The master cylinder 12 is essentially a hollow structure with a first or front manifold 16, a second or center manifold 18, and an end cap 20 that are in spaced apart, axially aligned relationship to one another. A cylindrically shaped thin-walled front sleeve 22 is positioned between the front manifold 16 and the center manifold 18. A similar cylindri-cally shaped rear sleeve 24 is positioned between the center manifold 18 and the end cap 20. The master cylinder 12 is held together by studs 26 that pass through each one of the manifolds 16 and 18 and the end cap 20. The studs 26 are threaded on each end and tension thereon is maintained by threaded nuts 28.

The actuating cylinder 14 is cylindrical throughout its internal and external configuration. As shown in the preferred embodiment of Figure 1, the actuating cylinder 14 is directly mounted to the end cap 20 with threaded fasteners 40. While the actuating cylinder 14 is shown in a lo parallel attitude with respect to the master cylinder 12, it is readily understood that the orientation and positioning of the actuating cylinder 14 can be altered to fit any particular application by providing an auxiliary port 42 to the end cap 20. A fluidic connection 38 can then be used between the master cylinder 12 and the actuating cylinder 14, as shown as an alternative embodiment in Figure 7.
Further, if desired, the actuating cylinder 14 may be mounted directly to the end cap's 20 auxiliary port 42 for a 90~ direct mounting configuration as shown in Figure 10.
Additionally, it is readily understood that this embodiment allows a single master cylinder 12 to control any desired number of actuating cylinders 14 in series or in parallel connection. Accordingly, the master cylinder 12 should be proportionally sized for the particular application. Figure 3 is a cross-sectional view of the overall apparatus 10 that is depicted in Figure 1. Figure 3 shows the pistons and their interrelationship to one another in an at rest condition. The front sleeve 22 may, if desired, have the same overall dimensions as the rear sleeve 24. The front and rear sleeves 22 and 24 are preferably manufactured from steel. The leading end 48 of the front sleeve 22 fits over a machined boss 50 on the front manifold 16. Even though close tolerances are maintained between the inside diameter of the front sleeve 22 and the outside diameter of the boss 50, it is desirable to utilize an O-ring 52 for sealing purposes. The trailing end 54 of the front sleeve 22 fits over a machined boss 56 on the center manifold 18. An O-ring 58 is utilized between the machined boss 56 and the interface with the front sleeve 22 to ensure a fluid tight joint. The leading end 60 of the rear sleeve 24 fits over a machined boss 62 on the center manifold 18. An 0-ring 64 is positioned so that it effects a fluid tight seal between the inside surface of the rear sleeve 24 and the machined boss 62. The trailing end 66 of the rear sleeve 24 fits over a machined boss 68 on a third or an annular manifold member 72. An O-ring 70 is used to ensure a fluid tight seal lo between the inside surface of the rear sleeve 24 and the machined boss 68. The end cap 20 is attached to the trailing end of the annular manifold member 72. A first 0-ring 74 ensures a fluid tight seal between the perimeter of the annular manifold member 72 and the end cap 20. A second O-ring 76 is utilized to maintain a fluid tight seal between a reduced portion of the annular manifold member 72 and the end cap 20. The annular manifold member 72 has a bore 78 that contains a groove 80 therein for an elastomeric seal 82 retained by a retainer cap 81, as best illustrated in Figure 5. The purpose of the reduced diameter bore 78 will be discussed in more detail below.

An intensifier piston 104 is positioned within a bore 106 in the front sleeve 22. The intensifier piston 104 is sealed against the bore 106 by means of an O-ring 108. An intensifier piston rod 110 is centrally attached to the intensifier piston 104 by a threaded fastener 118. The intensifier piston rod 110 passes through a bore 120 that is located in the center manifold 18. A groove 122 within the bore 120 carries an 0-ring 124 provided as a seal between the center manifold 18 and the intensifier piston rod 110.

An annular-shaped floating reservoir piston 132 is positioned over the intensifier piston rod 110. A portion of an inner surface 126 of the floating reservoir piston 132 is elongated and tapered to closely mate with a frustoconi-cally shaped portion 128 of the annular manifold member 72.

CA 02238l39 l998-07-l3 The reservoir piston 132 iS positioned within a bore 134 within the rear sleeve 24. The floating reservoir piston 132 iS sealed against the surface of the bore 134 by means of a leading end O-ring 136 and a trailing end O-ring 138, located in grooves 140 and 142, respectively, in the floating reservoir piston 132. The floating reservoir piston 132 iS also sealed against the intensifier piston rod 110 along which it slides by O-rings 144 and 146 which seal the floating reservoir piston 132 against the intensifier o piston rod 110 on opposite sides of a relief passage 148 within the floating reservoir piston 132. The relief passage 148 places the area between the leading and trailing end O-rings 136 and 138 on the perimeter of the floating reservoir piston 132 and the area between the O-rings 144 and 146 adjacent the intensifier piston rod 110 in fluid communication, thus preventing the build up of residual pressure between the leading and trailing end O-rings on the floating reservoir piston 132. The arrangement of the floating reservoir piston 132 on the intensifier piston rod 20 110 within the rear sleeve creates two fluid chambers 152 and 154 within the area of the rear sleeve 24. The fluid chamber 152 lies between the annular manifold member 72 and the internal surface 126 of the floating reservoir piston 132. The fluid chamber 154 lies between the center manifold 18 and a recess in the leading face of the floating reservoir piston 132.

The front manifold 16 contains a fluid chamber 156 and a threaded bore 160. An additional fluid chamber 162 lies 30 between the intensifier piston 104 and the center manifold 18. The center manifold 18 contains a first bore or port 86 that is in communication with the chamber 154. A second bore or port 164 iS in communication with the additional fluid chamber 162. The end cap 20 contains a bore 168 that is in communication with the chamber 152 through the reduced diameter bore 78 in the annular manifold member 72. In addition, the end cap 20 has a supply port 90 which is also in fluidic communication with the chamber 152 via a supply passage 92 in the annular manifold member 72. A reservoir 94, positioned in any convenient location, is fluidically connected to the supply port so for purposes of supplying the chamber 152 with hydraulic fluid. A one-way check valve 96 is positioned between the reservoir 94 and the supply port 90 to allow fluid to be supplied to the chamber 152 and also to prevent backflow from the chamber 152 to the reservoir 94.

The actuating cylinder 14 has an external cylindrical configuration over its axial extent. The rear portion of the actuating cylinder 14 has a bore 174 that is threaded (not shown) for communication with the bore 168 of the end cap 20.
The interior of the actuating cylinder 14 is formed by an axial bore 176 that extends over approximately the rear one half of the actuating cylinder 14. The remaining or forward one half of the interior of the actuating cylinder 14 is formed by an axially extending bore 178 that is of greater diameter than the axial bore 176 of the rear half of the actuating cylinder. A radially extending shoulder 180 forms the intersection between the bores 176 and 178. A sleeve 182 is positioned within the bore 178 of the actuating cylinder 14. The shoulder 180 acts as a stop for the sleeve 182 thus defining its axial position within the actuating cylinder 14.

A rear piston 184 is positioned within the bore 176. The rear piston 184 has a first 0-ring seal and backup rings 185 positioned within a groove 187, and a second 0-ring seal 186 positioned within a groove 188 located in the cylindrical exterior surface of the rear piston 184 as more clearly shown in Figure 6. A piston rod 46 has one end thereof attached to the rear piston 184. The piston rod 46 has a reduced diameter end 192 with a threaded portion (not shown) that extends through an axially aligned bore 194 in the rear piston 184. The rear piston 184 is attached to the piston rod 46 by means of a threaded nut 196 that engages the threaded portion threads (not shown) on the end of the reduced diameter end 192 of the piston rod 46. The piston rod 46 extends from the rear piston 184 through the entire axial extent to the right, as viewed in Figure 3, where it exits the actuating cylinder 14 as an unencumbered cantilevered end 198.

Returning once again to the actuating cylinder 14, a forward piston 200 is press fit onto the piston rod 46. The forward piston 200 is located generally toward the mid-portion of the axial extent of the piston rod 46. The forward piston 200 has a peripheral groove 202 that contains an 0-ring 204. The sleeve 182 accommodates the forward piston 200 within a bore 206 of the sleeve 182. The 0-ring 204 seats against the surface of the bore 206. The sleeve 182 contains a second bore 212 that permits the piston rod 46 to pass therethrough, forming a chamber 210 between the forward piston 200 and the shoulder formed between the bore 206 and the second bore 212.
The second bore 212 contains a groove 214 in which an 0-ring 216 is positioned for providing a seal between the sleeve 182 and the piston rod 46. The sleeve 182 contains a groove 218 positioned in its external surface so that an 0-ring 220 can be placed therein to effect a seal between the sleeve 182 and the bore 178 of the actuating cylinder 14.

The section of the piston rod 46 located to the right of the forward piston 200, as viewed in Figure 3, has a diameter that is less than the bore 206 of the sleeve 182, thus forming a chamber 222. The chamber 222 is in communication with a central bore 226 through the rear portion of the piston rod 46 by way of a radial passage in the piston rod 46. In a similar manner, the rear piston 184 has a radial bore 228 extending between the 0-ring seals 185 and 186 that is in communication with the central bore 226. A chamber 231, which is positioned to the right of the rear piston 184, is in communication with a passage 232 in the sleeve 182. A
chamber 236, located to the left of the rear piston 184 as viewed in Figure 3, iS in communication with the fluid chamber 152 of the master cylinder 12 via the bore 174 of the actuating cylinder 14, the passage 168 in the end cap 20, and the bore 78 in the annular manifold member 72.

A retaining bushing 44 iS mounted to the forward portion of the actuating cylinder 14 and has an external part cylindrical section 240 that fits into the bore 178 to establish the chamber 222. The retaining bushing 44 iS
immobilized by means of a retaining ring 242 that coacts with a groove 244 in the wall of the bore 178 in the actuating cylinder 14 and with a groove 246 that is milled in the external surface of the external part cylindrical section 240.

As can be better seen in Figure 1, the piston rod 46 contains a milled planar area 248 on one side and a similar milled planar area 250 on the other side thereof which is optional.
The purpose of the milled planar areas 248 and 250 iS to provide orientation to the piston rod 46 SO that it will not rotate and cause misalignment with a nonsymmetrical tool that may be affixed to the cantilevered end 198 of the piston rod 46.

Figure 4 is a part sectional view of an embodiment that employs a trunnion 254 as an integral part of the actuating cylinder 14. Figure 4 shows the trunnion 254 engaged with mounting slots 256 within a mounting bracket 258. This arrangement allows the actuating cylinder 14 to be pivoted to the preferred attitude for a particular application.
Figure 9 is a part sectional view of an embodiment that employs a load cell device within the piston rod 46 of the actuating cylinder 14. Figure 9 shows the sleeve 182, the piston rod 46 and the retaining bushing 44 similar to like components shown in Figure 3. The piston rod 46 has a reduced diameter cylindrical section 30. The reduced diameter cylindrical section 30 telescopes within a piston rod adapter 32. The piston rod adapter 32 has an external cylindrical surface that fits within a bore 34 in the retaining bushing 44. The piston rod adapter 32 has an internal bore 36 into which the telescoping end of the piston rod 46 fits. A load cell 35 is positioned within the lo bore 36 and a compression spring 37 is aligned within the bore 36 between the end of the piston rod 46 and the load cell 35. In order to retain the piston rod adapter 32 on the end of the piston rod 46, a pin 33 is installed in a bore 31 that is diametrically aligned with respect to the piston rod 46. The pin 33 protrudes beyond the external surface of the reduced diameter cylindrical section 30. The ends of the pin 33 fit into slots 29 that are milled into the piston rod adapter 32. In this manner, the piston rod adapter 32 has a limited degree of axial movement with respect to the piston rod 46. The piston rod adapter 32 has a radially aligned bore 39 that permits electrical lead wires 41 of the load cell 35 to exit the interior of the piston rod adapter 32. During operation of the overall apparatus the piston rod 46 causes the compression spring 37 to exert a force on the load cell 35. After the load has been released from the load cell, the compression spring 37 will cause the piston rod adapter 32 to move axially subject to the constraints of the pin 33 and the slots 29.

During the assembly of the overall apparatus 10, great care must be taken to preserve the integrity of the seals, particularly the 0-rings which are subject to the nicks caused by assembly. The master cylinder is assembled by installing the appropriate seals on the reservoir piston 132 and the intensifier piston 104. The intensifier piston 104 is affixed to the end of the intensifier piston rod 110 by the threaded fastener 118. The intensifier piston rod 110 is then inserted through the bore 120 in the center manifold 18. The reservoir piston 132 is then slid over the free end of the intensifier piston rod 110. The front and rear sleeves 22 and 24 are then installed over the respective bosses 56 and 62 on the center manifold 18. The front manifold 16 and the annular manifold member 72 are then positioned so that their respective bosses 50 and 68 slide within the ends of the front and rear sleeves 22 and 24.
lo The end cap 20 is then positioned against the annular manifold member 72, aligning the bore 168 with the reduced diameter bore 78 and the supply port 90 with the supply passage 92. The four studs 26 are then installed in the holes (not shown) within the front and center manifolds 16 and 18 and the end cap 20. The studs 26 are then tensioned by the installation of the nuts 28.

During the assembly of the actuating cylinder 14, the forward piston 200 is press fit onto the piston rod 46 as seen in Figure 3, the fit being an interference fit. The sleeve 182 is then positioned over the left end (as viewed in Figure 3) of the piston rod 46. Next, the rear piston 184 is affixed to the end of the piston rod 46 by the nut 196. The rear piston 184, the piston rod 46 and the sleeve 182 are installed within the bores 176 and 178 of the actuating cylinder 14. The retaining bushing 44 is then slid over the cantilevered or free end 198 of the piston rod 46. The retaining bushing 44 is then moved into locking arrangement with the retaining ring 242. The actuating cylinder 14 is then mounted to the end cap 20 with the threaded fasteners 40.

Figure 8A is a cross-sectional view that shows the position of the pistons and piston rods when the overall apparatus 10 is in the fully retracted position. At the commencement of a cycle of the overall apparatus 10, the intensifier piston 10~

is held to the extreme right end of the chamber 162 by high air pressure, as shown, through the bore 120 and its external port. Consequently, the end of the intensifier piston rod 110 is retracted to a position outside of the bore 78 permitting the fluid chamber 152 to communicate with the bore 78. The reservoir piston 132 is to the extreme right end of travel against the center manifold 18. In the actuating cylinder 14 portion of the overall apparatus 10, the rear piston 184 is positioned toward the extreme left toward the end cap 20 defining the greatest extent of the chamber 231, therefore, the extreme right free end of the piston rod 46 is almost entirely retracted within the confinement of the actuating cylinder 14. The forward piston 200, acting as an integral part of the piston rod 46, is positioned against the shoulder defined by the bores 212 and 206.

Figure 8B is a cross-sectional view that shows the position of the pistons and piston rods after the overall apparatus 10 has been actuated to begin a work cycle. Air pressure is introduced to the fluid chamber 154 through the first bore 86 causing the reservoir piston 132 to move toward the left.
The oil to the left of the reservoir piston 132 begins to exit the fluid chamber 152 and, being prevented from returning to the reservoir 94 by the check valve 96, travels via the reduced diameter bore 78 and the bore 168 into the chamber 236. The increase in volume of oil in the chamber 236 causes the rear piston 184 to move rapidly to the right.
As the rear piston moves toward the right, air is exhausted from the chamber 231 through the passage 232. Since the forward piston 200 acts as a part of the piston rod 46, the forward piston 200 also moves toward the right thus causing an ingress of atmospheric air into the chamber 210 and an egress of atmospheric air from the chamber 222. After the initial introduction of air pressure to the fluid chamber 154 at the right of the reservoir piston 132 there is a rapid deployment of the piston rod 46 to the right where its travel is halted by an interception with, for example, a workpiece 47. It has been determined through experimentation that performance characteristics may be diminished if the forward piston 200 is driven toward the right by introducing air pressure into the chamber 210 during the commencement of the cycle illustrated in Figure 8B. The cause for this loss in performance is believed to be the result of a ~sucking action" created when the forward piston 200, as a result of air pressure introduced into the chamber 210, begins to lo travel before or travels at a faster rate than the reservoir piston 132, thereby forming a partial vacuum in the chamber 236. This in turn provides an additional force that compels the reservoir piston 132 to travel to the left faster than intended by the action of the air pressure in the fluid chamber 154. Figure 8C is a cross-sectional view similar to that shown in Figures 8A and 8B that shows the final stage of the work cycle of the overall apparatus 10. Since rapid deployment of the piston rod 46 has brought a tool (not shown) carried by it into contact with the workpiece 47, the load must be increased beyond the capability of the air pressure normally found at an industrial site. Consequently, air pressure is introduced into the chamber 156 which is positioned to the right of the intensifier piston 104. As the intensifier piston 104 moves to the left, the tip of the intensifier piston rod 110 enters the bore 78 in the annular manifold member 72, causing the oil trapped before it to act as a closed loop system between the intensifier piston rod 110, the bore 78, and the chamber 236. The continued travel of the intensifier piston rod 110 into the bore 78 acts on the oil in the chamber 236 urging the rear piston 184 to the right, delivering a greatly increased or intensified force to the piston rod 46. The actual movement of the piston rod 46 has been exaggerated in Figure 8C for purposes of illustrating the movement thereof. The increased movement of the forward piston 200 to the right will exhaust additional atmospheric air from the chamber 222 and cause an influx of additional atmospheric air into the chamber 210. Thus, there will be a combined hydraulic intensifying force introduced to the piston rod 46.

On the return stroke, both the intensifier piston 104 and the rear piston 184 are driven back to their original positions by introducing high pressure air into their respective chambers 162 and 231 through the bore 164 and the passage 232. The return stroke of the rear piston 184 acts to return the reservoir piston 132 to its original position to the right end of the fluid chamber 152 against the center 0 manifold. As an added feature to ensure adequate performance of the apparatus 10, there is provided a proximity sensor 252 for sensing the position of the reservoir piston 132 in relation to the extreme left end of the fluid chamber 152. As shown in Figure 3, the proximity sensor 252 is located adjacent the extreme left end of the fluid chamber 152 and can be instrumented through any conventional means to relay a warning signal when the reservoir piston 132 is approaching the end of its stroke capability within the fluid chamber 152. This condition would arise if, for example, the hydraulic fluid within the fluid chamber 152 has dropped to an unacceptable level. By way of a warning signal, an operator of the apparatus 10 is put on notice that replenishment of the hydraulic system is necessary. Figure 11 is a schematic fluid diagram according to the present invention and the controls that achieve the fluid motion. For purposes of the present invention the fluids have been described as air and oil. Figure 11 shows a simplified layout of the pistons and piston rods. Since the oil within the overall apparatus 10 is self-contained, the oil has been shown for clarity as section lines. In order to operate the overall apparatus through its entire work cycle, only external air pressure need be applied. For purposes of explanation, it is assumed the overall apparatus 10 is coupled to an air supply 272. Air under pressure is supplied to a three-way valve mechanism 274 which is a solenoid actuated spring return device. The air under pressure exits the air supply through a line 276 and travels through the three-way valve mechanism 274 to a line 278 and to the chamber 231. The air supply 272 also supplies air under pressure to a line 304 which is connected to the two-way valve mechanism 288 which supplies air under pressure to the chamber 162. The air pressure supplied to the chamber 231 causes the rear piston 184 to move to the left as viewed in Figure 8A forcing the oil from the chamber 236 into the fluid chamber 152 and urging the floating reservoir piston 132 to the right. As the floating reservoir piston 132 moves 0 to the right, air is exhausted from the fluid chamber 154 through a line 282 to the valve mechanism 274 which permits the expelled air to enter a line 284 and travel to an exhaust port 286 which may, if desired, be a device such as a muffler to attenuate the noise level of the exhausting air. The air pressure delivered via a line 280 to the chamber 162 causes the intensifier piston 104 to remain to the right, ensuring that the tip of the intensifier piston rod 110 does not impede the flow of oil into the fluid chamber 152. The chamber 156 is connected to the two-way valve mechanism 288 by a line 290. In the unenergized position, the two-way valve mechanism 288 permits pressurized air in the chamber 156 to exhaust through the line 290 to a line 292 and pass to the exhaust port 286. At the start of the cycle, a solenoid 294 on the normally open three-way valve mechanism 274 is energized by the movement of a workpiece into a work station or by other means that connect to an electrical source to the solenoid. The energizing of the solenoid 294 connects the air supply line 276 to the line 282 pressurizing the fluid chamber 154 through the port in the manifold 18 through the first bore 86 which causes the floating reservoir piston 132 to move to the left, forcing oil from the fluid chamber 152 into the chamber 236. Oil entering the chamber 236 causes the rear piston 184 to move rapidly to the right, hence the piston rod 46 moves to the right along with the forward piston 200. The energizing of the solenoid 294 on the three-way valve mechanism 274 also causes the air supply line 278 to the chamber 231 to become connected to the exhaust line - - -284. As the forward piston 200 moves to the right, air is exhausted from the chamber 222 through a line 295 and air from the exhaust port 286 is drawn through a line 296 to the chamber 210. After the piston rod 46 has made its rapid advance toward and against a workpiece such as is identified by numeral 298, the pressure, or an electrical sensing switch such as 300, energizes a solenoid 302 on the normally closed two-way valve mechanism 288 causing the line 304 to be switched from its connection to line 280 to be reversed and lo be connected to the line 290 and at the same time the line 280 is switched to be connected to the exhaust line 292. The air pressure delivered by the line 290 to the chamber 156 causes the intensifier piston 104 to move to the left thus permitting the tip of the intensifier piston rod 110 to enter the bore 78 and apply an intensified pressure on the oil in the chamber 236. The increased force supplied to the rear piston 184 is transferred to the piston rod 46 and to the workpiece 298. At the command of an operator or by auto-matic timing, the solenoids 294 and 302 are deenergized, permitting springs 306 and 308 to return the valve mechanisms 274 and 288 to their original starting positions. It is to be noted that by utilizing air to hold the intensifier piston positively in place while the floating reservoir piston is sub~ected to air pressure avoids the need for using springs and results in a more positive control of the intensifier piston. It is also to be noted that appropriate bleed passages are provided, as is customary in the art, between cooperating seals to prevent the buildup of residual pressures due to blowby.
By way of illustration, the intensifier piston rod 110 has a diameter of 0.5 inches and the intensifier and rear pistons 104 and 184 each have a diameter of 1.75 inches. The in-crease in the pressure delivered to the rear piston 184 varies as the square of the diameter, 1.75 squared divided by 0.5 squared yields a pressure increase of 12.25. Thus, if typical shop air at 80 p.s.i. is delivered to the intensifier piston, there will be 980 p.s.i. delivered to the rear piston 184.

In a second embodiment of the present invention, Figure 12 illustrates a load intensification apparatus identified by numeral 410. The load intensification apparatus 410 of the second embodiment is distinguished from the load intensifi-cation apparatus 10 of the first embodiment by the provision of an intermediate retract position capability. As will be lo readily seen, the intermediate retract position facilitates multiple weld operations by reducing the cycle time between successive welds which do not require the full clearance provided by the full retract position of the overall apparatus 10.

In a manner similar to the first embodiment, Figure 12 shows the overall apparatus 410 of the second embodiment having a master cylinder 412 and an actuating cylinder 414 which together constitute two distinct subassemblies or housings of the overall apparatus 410. The overall apparatus 410 of the second embodiment is constructed nearly identically to the overall apparatus 10 of the first embodiment except for specific modifications to the master cylinder 412 which will be delineated below.

Similar to the first embodiment, the master cylinder 412 of the second embodiment has a front manifold 416, a center manifold 418, and an annular manifold member 472 which are in spaced-apart, axially-aligned relationship to one another. Cylindrically-shaped front and rear sleeves 422 and 424 are positioned between the front and center manifold 416 and 418, and the center manifold and annular manifold member 418 and 472, respectively. The front and rear sleeves 422 and 424 form a front bore 506 and a rear bore 534, respectively. Within the rear bore 534 there is provided a retaining ring 538 within an internal groove 540 CA 02238l39 l998-07-l3 which is positioned approximately midway between the annular manifold member 472 and the center manifold 418. The retaining ring 538 iS of sufficient strength to act as a piston stop in a manner to be described later.

The annular manifold member 472 has an elongated annular portion 473 with an outer cylindrical surface 528 extending towards the center manifold 418. The interior surface of the elongated annular portion 473 provides a reduced dia-o meter bore 478. An end cap 420 in part is mounted to the annular manifold member 472 on a side opposite the elongated annular portion 473. The end cap 420 has a bore 568 that is in communication with the reduced diameter bore 478 of the annular manifold member 472.

As with the first embodiment, the second embodiment has an intensifier piston 504 which is attached to an intensifier piston rod 510 and is positioned within the front bore 506.
The intensifier piston 504 divides the front bore 506 into a 20 first chamber 556 adjacent the front manifold 416, and a second chamber S62 adjacent the center manifold 418. The first chamber 556 iS in fluidic communication with a port 560 in the front manifold 416. The second chamber 562 iS in fluidic communication with a port 564 within the center manifold 418. The intensifier piston rod 510 passes through a bore 520 located in the center manifold 418 and extends short of the reduced diameter bore 478 of the annular manifold member 472.

Similar to the first embodiment, a floating reservoir piston 532 of the second embodiment is positioned over the intensi-fier piston rod 510 within the rear bore 534. The floating reservoir piston 532 divides the rear bore 534 into a third chamber 554 adjacent the center manifold 418, and a fourth chamber 552 adjacent the annular manifold member 472. The third chamber 554 iS in fluidic communication with a port 436 in the center manifold 418. The fourth chamber 552 is in fluidic communication with the reduced diameter bore 478 of the annular manifold member 472 and the bore 568 of the end cap 420. The end cap 420 also is provided with a supply port 490 which is in fluidic communication with the rear bore 534 through a supply passage 482 in the annular manifold member 472.

In contrast to the first embodiment, the floating reservoir o piston 532 is truncated and does not mate with the cylindri-cal surface 528 of the annular manifold member 472.
Instead, the floating reservoir piston 532 is retained within the rear bore 534 between the center manifold 418 and the retaining ring 538.

In addition, in the second embodiment a retract piston 536 which is positioned over the outer cylindrical surface 528 of the annular manifold member 472 is provided. The retract piston 536 defines a retract chamber 553 within the rear bore 534 between the annular manifold member 472 and the retract piston 536. The retract piston 536 operates between the annular manifold member 472 and the retaining ring 538 such that the retract piston 536 always remains piloted upon the outer cylindrical surface 528 of the annular manifold member 472. Further, the retract piston 536 is constructed such that it cannot interrupt the fluidic path between the fourth chamber 552 and the reduced diameter bore 478. The retract chamber 553 is in communication with the supply port 490 via the supply passage 482 for purposes of actuating the retract piston 536.

Similar to the first embodiment, a proximity sensor 652 is provided for sensing the position of the floating reservoir piston 532 in relation to the retaining ring 538. The proximity sensor 652 serves to warn an operator that the quantity of hydraulic fluid within the fourth chamber 552 is low and needs replenishing. The hydraulic fluid is introduced into the fourth ehamber 552 through a fill port 542 positioned in proximity to the retaining ring 538.

The actuating cylinder 414 is constructed identically to the actuating cylinder 14 of the first embodiment. As shown, the S actuating cylinder 414 is mounted to the end eap 420, but as noted with the first embodiment, the actuating cylinder 414 can be fluidically connected to the end cap 420 with a suitable fluidic connection. The rear portion of the actuating cylinder 414 has a bore 576 that is in fluidic communication with the bore 568 of the end cap 420. A rear piston 584 is positioned within the bore 576. The rear piston 584 is attached to a piston rod 446 which extends from the rear piston 584 through the entire axial extent to the right, where it exits the actuating cylinder 414 as an lS unencumbered cantilevered end 598.

The rear piston 584 divides the bore 576 into a fifth and sixth chamber 631 and 636, respectively. The sixth chamber 636 is in eommunication with the fourth chamber 552 of the master cylinder 412 via the passage 568 in the end cap 420 and the reduced diameter bore 478 in the annular manifold member 472.

Operation of the seeond embodiment is nearly identieal to the first embodiment exeept for the ability of the foree intensifieation apparatus 410 to reaeh an intermediate retraet position from either the fully retraeted or fully extended position. Figure 13A is a eross-seetional view that shows the position of the pistons and piston rods when the overall apparatus 410 is in the fully retracted position. At the commencement of a cycle, the intensifier piston 504 is held to the extreme right end of the front bore 506 by high pressure air in the second chamber 562, as shown.
Consequently, the end of the intensifier piston rod 510 is retracted to a position outside of the reduced diameter bore 478 permitting the fourth chamber 552 to communicate with the reduced diameter bore 478. The floating reservoir piston 532 is to the extreme right end of its travel against the center manifold 418. The retract piston 536 is to the extreme left end of its travel against the annular manifold member 472.

In the actuating cylinder 414, the rear piston 584 is held by high pressure air to the extreme left toward the end cap lo 420 defining the greatest extent of the fifth chamber 631.
Therefore, the extreme right free end of the piston rod 446 is almost entirely retracted within the confinement of the actuating cylinder 414.

Figure 13B is a cross-sectional view that shows the position of the pistons and piston rods after the overall apparatus 10 has been actuated to the intermediate retract position at the start of a work cycle. Air pressure is introduced into the retract chamber 553 through the supply port 490, causing the retract piston 536 to move toward the center manifold 418 until it abuts against the retaining ring 538. A volume of oil corresponding to the volume displaced by the retract piston 536 exits the fourth chamber 552 and travels via the reduced diameter bore 478 and the bore 568 to the sixth chamber 636. The increase in volume of oil in the sixth chamber 636 causes the rear piston 584 to move rapidly to the right. Consequently, there is a rapid deployment of the piston rod 446 to the right where its travel is arrested a predetermined distance from a workpiece 447, serving as an intermediate retract position for the overall apparatus 410.
The predetermined distance traveled by the piston rod 446 is determined directly by the volume of oil displaced by the retract piston 536.

Figure 13C is a cross-sectional view that shows the position of the pistons and piston rods after the overall apparatus 410 has been actuated to engage the workpiece 447. Figure 13C corresponds to Figure 8B of the first embodiment, and the operation of the overall apparatus 410 corresponds accordingly. Air pressure is introduced to the third cham-ber 554 causing the floating reservoir piston 532 to move to the left toward the retract piston 536. An additional volume of oil corresponding to the volume displaced by the floating reservoir piston 532 exits the fourth chamber 552 and travels via the reduced diameter bore 478 and the bore 568 into the sixth chamber 636, further causing the rear o piston 584 to mover rapidly to the right. The piston rod 446 consequently moves rapidly to the right where its travel is halted by its interception with the workpiece 447.

Figure 13D is a cross-sectional view corresponding to Figure 8C of the first embodiment, showing the final stage of the work cycle of the overall apparatus 410. For achieving force intensification at the piston rod 446, air pressure is introduced into the first chamber 556 to the right of the intensifier piston 504. As the intensifier piston 504 moves to the left, the tip of the intensifier piston rod 510 enters the reduced diameter bore 478 in the annular manifold member 472, causing the oil trapped before it to act as a closed system between the intensifier rod 510, the bore reduced diameter 478, the bore 568 and the sixth chamber 636. The continued travel of the intensifier piston rod 510 into the reduced diameter bore 478 acts on the oil in the sixth chamber 636 urging the rear piston 584 to the right, delivering a greatly increased or intensified force to the piston rod 446.
According to the second embodiment of the present invention, the overall apparatus 410 does not automatically return to the fully retracted position shown in Figure 13A, but returns to the intermediate retract position shown in 13B
for purposes of facilitating rapid successive weld opera-tions. To return the overall apparatus 410 to the inter-mediate retract position from the intensified position, air pressure is released from the first chamber 556 and reintro-duced in the second chamber 562 to drive the intensifier piston 504 back to its original position. Consequently, the intensifier piston rod 510 is withdrawn from the reduced diameter bore 478, simultaneously reducing the pressure against the rear piston 584 in the sixth chamber 636. The floating reservoir piston 532 is driven back to its original position by the partial return stroke of the rear piston 584 in cooperation with the releasing of the high pressure air lo from the third chamber 554 which had originally moved and held the floating reservoir piston 532 in its actuated position. The rear piston 584 and, therefore, the piston rod 446, is retracted to the intermediate retract position upon the floating reservoir piston 532 being returned to its original position. The rear piston 584 and the piston rod 446 retract no further because of the volume of oil yet displaced by the retract piston 536.

At the end of a multiple weld operation, the operation of the overall apparatus 410 is again similar to the overall apparatus 10 of the first embodiment. From the intermediate retract position, air pressure is re-introduced into the fifth chamber 631, driving the rear piston 584 back to its original position. Upon release of the high pressure air in the retract chamber 553 which had originally moved and held the retract piston 536 in its actuated position, the retract piston 536 is returned to its original position adjacent the annular manifold 472 by the return stroke of rear piston 584.
From the above, it can be appreciated that rapid successive weld operations can be accomplished more quickly by elimin-ating the first embodiment's requirement for a complete retraction of the piston rod 446 between weld operations.
The overall apparatus 410 under the second embodiment can rapidly perform a successive number of weld operations by first extending to the intermediate retract position (Figure 13B), further extending to the weld position (Figure 13C), intensifying during the weld operation (Figure 13D), partially retracting to the intermediate retract position (Figure 13B) which is designed to sufficiently clear the workpiece 447, and then return to the weld position (Figure 13D) for an additional intensification and weld operation.
When the desired series of weld operations is completed, the overall apparatus can then be cycled directly from the lo intermediate retract position (Figure 13B) to the full retract position (Figure 13A) for purposes of providing maximum clearance with the workpiece 447.

A fluid control system for the second embodiment of the present invention would be analogous to the schematic fluid diagram of the first embodiment illustrated in Figure 11.
Those with ordinary skill in the art can readily recognize the minor modifications necessary to accommodate the opera-tional requirements of the retract piston 536. By example, a solenoid-operated valve can be employed to operate the retract piston 536 between its "stowed" position when the piston rod 446 is fully retracted, and its "deployed"
position when the piston rod 446 is at the intermediate retract, weld and intensified positions. In addition, the three-way valve mechanism 274 of the first embodiment can be modified to provide a valve position in which both lines 282 and 278 are exhausted to the exhaust port 286 when the overall apparatus is in the intermediate retract position.

Figure 14 depicts yet a further embodiment of the invention wherein the actuating cylinder can be arranged to add any attitude with respect to the master cylinder in an arrange-ment as provided which permits viewing of the self-contained hydraulic system to assure replenishing thereof, as necessary. The embodiment illustrated differs from the preferred embodiment in that a viewing tube 730 for viewing the hydraulic fluid contained within the master cylinder 712 spans the distance between the center manifold 718 and the rear manifold 720. A nipple 732 is positioned in axial alignment with the viewing tube 730 and a quick disconnect fitting 734 is coupled to the cantilevered end of the nipple 732. The quick disconnect fitting 734 provides for easy access to the hydraulic system should the addition of hydraulic fluid become necessary.

A compression fitting 90~ elbow 736 is attached to the lo rear manifold 720. The elbow 736 is in turn coupled with an elastomeric tube 738 that is made of urethane or other suitable material that can withstand contact with hydraulic oil and reasonable pressures generated thereby. The elastomeric tube 738 is coupled to a straight compression fitting 740.

An actuating cylinder 714 is essentially cylindrical throughout its internal and external configuration and at the back end has a tapped hole to accept the compression fitting 740. The front end of the actuating cylinder is supported by a mounting plate 742. The mounting plate 742 is cantilevered in a downward direction from its rigid support on the front manifold 716. While the actuating cylinder 714 is shown in a parallel attitude with respect to the master cylinder 712, it is readily understandable that the flexible nature of the elastomeric tube 738, as well as its selectable, varying length, permits orientation or positioning of the actuating cylinder 714 to assume any location with respect to the master cylinder 712. A retaining bushing 744 is attached to the front end of the actuating cylinder 714. The retaining bushing 744 permits the end of a piston rod 746 to protrude therefrom. By way of example, a tool 747, such as an electrode for welding purposes, can be affixed to the cantilevered end of the piston rod 746.

Figure 14 shows the pistons and their interrelationship to one another. The front 722 and rear 724 sleeves as in the preferred embodiments are assembled to their respective manifolds similar to the preferred embodiment. An end cap 772 is attached to the trailing end of the rear manifold 720.
The end cap 772 has a threaded section that engages similar threads in an axially aligned bore 774 in the rear manifold 720. An o-ring 776 is utilized to maintain a fluid tight seal between the end cap 772 and the rear manifold 720. The end cap 772 has a reduced diameter bore 778 that contains a groove 780 for the elastomeric seal 782. The purpose of the reduced diameter bore 778 will be discussed in more detail below.

The center manifold 718 has a 90~ elbow fitting threadedly engaged in an upper threaded bore 786. The elbow fitting 784 has its non-threaded end 788 directed toward the left or toward the rear manifold 720. A tee fitting 790 has its stem end 792 threadedly engaged within a threaded lower bore 794 in the rear manifold 720. The lower bore 794 is located on the top of the rear manifold 720. The top of the tee fitting 790 is aligned so that its axis is parallel with the longitudinal axis of the master cylinder 712. The viewing tube 730 is aligned between the tee fitting 790 and the end 788 of the elbow fitting 784. 0-ring seals 796 and 798 effect seals at the leading and trailing ends 800 and 802 of the viewing tube 730 with the respective elbow fitting 784 and tee fitting 790. The viewing tube 730 can be fabricated from tempered glass tubing or high strength plastic material.
The nipple 732 is threadedly attached to the end of the tee fitting 790 and the quick disconnect fitting 734 is attached to the nipple 732. Thus, the quick disconnect fitting 734, the nipple 732, and the viewing tube 730 are in axial alignment with one another.

As in the preferred embodiment, an intensifier piston 804 is positioned within a bore 806 in the front sleeve 722.
The intensifier piston 804 is sealed against the bore 806 by means of an 0-ring 808. An intensifier piston rod 810 is centrally attached to the intensifier piston 804. A reduced diameter end 812 of the intensifier piston rod 810 is positioned within a bore 814 in the intensifier piston 804.
The intensifier piston 804 is immobilized by the attachment of a threaded fastener nut 818 to a threaded portion of the reduced diameter end 812. The intensifier piston rod 810 passes through a bore 820 that is located in the center manifold 718. A groove 822 within the bore 820 carries an 0-ring 824 provided for a seal between the center manifold 718 and the intensifier piston rod 810. The intensifier piston rod 810 also passes through a bore 826 that is located within the rear manifold 720. A seal is maintained between the rear manifold 720 and the intensifier piston rod 810 by means of an 0-ring 828 that is positioned within a groove 830 in the wall of the bore 826.

A floating reservoir piston 832 is trained over the intensifier piston rod 810. The floating reservoir piston 832 is positioned within a bore 834 in the rear sleeve 724.
The floating reservoir piston 832 is sealed against the surface of the bore 834 by means of an 0-ring 836 and wiper seals 838 and 840 that are positioned on each side of the 0-ring 836. The 0-ring 836 and accompanying wiper seals 838 and 840 are positioned within a groove 842 that is located in a peripheral surface of the floating reservoir piston 832.
The floating reservoir piston 832 is also sealed against the intensifier piston rod 810 along which it slides. A glide or wiper ring 844 and an adjacent 0-ring 846 are positioned in grooves 848 and 850, respectively. The positioning of the floating reservoir piston 832 on the intensifier piston rod 810 creates two fluid chambers 852 and 854 within the area of the rear sleeve 724. The first fluid chamber 852 lies between the rear manifold 720 and the floating reservoir piston 832. The second fluid chamber 854 lies between the center manifold and the floating reservoir piston 832.

The front manifold 716 contains a fluid chamber 856 and an elbow fitting 858 that is threaded into a threaded bore 860 of the front manifold. The bore 860 is in communication with the fluid chamber 856 and the elbow fitting 858. An additional fluid chamber 862 lies between the intensifier piston 804 and the center manifold 718. The center manifold 718 contains the upper bore 786 that is in communication with the second chamber 854 and the elbow fitting 784. A lower bore 864 is in communication with the additional fluid chamber 862 and an elbow 866 that is threaded into the bottom of the center manifold 718. The rear manifold 720 contains a bore 868 that is in communication with the first fluid chamber 852 and the interior of an elbow fitting 870 that is anchored in the rear manifold 720.

The actuating cylinder 714, like in the preferred embodiment, has an external cylindrical configuration over its axial extent. The rear portion of the actuating cylinder 714 has a section 872 of reduced external diameter. The end of the section 872 contains a bore 874 that is threaded (not shown) for coupling with the compression fitting 740. The interior of the actuating cylinder 714 is formed by an axial bore 876 that extends over approximately the rear half of the actuating cylinder 714. The remaining or forward half of the actuating cylinder 714 is formed by an axially extending bore 878 that is of greater diameter than the axial bore 876 of the rear half of the actuating cylinder. A radially extending shoulder 880 forms the intersection between the bores 876 and 878. A sleeve 882 is positioned primarily within the bore 878 of the actuating cylinder 714. A portion of the sleeve 882 is of reduced external diameter so that it fits within the bore 876. The reduced external diameter -portion of the sleeve 882 creates a reentrant notch that coacts with the shoulder 880 of the actuating cylinder 714.
The shoulder 880 acts as a stop for the sleeve 882, defining its axial position within the actuating cylinder 714.

A rear piston 884 is positioned within the bore 876.
The rear piston 884 has on O-ring seal 886 positioned within a groove 888 located in the cylindrical exterior surface of the rear piston 884. The piston rod 746 has one end thereof attached to the rear piston 884. The piston rod 746 has a reduced diameter end portion 892 that extends through an axially aligned bore 894 in the rear piston 884. The rear piston 884 is attached to the piston rod 746 by means of a threaded nut 896 that engages threads (not shown) on the end of the reduced diameter end portion 892 of the piston rod 746. The piston rod 746 extends from the rear piston 884 through the entire axial extent to the right, as viewed in Figure 2, where it exits as an unencumbered cantilevered end 898.

Returning once again to the sleeve 882, a forward piston 900 is machined into the piston rod 746 as an integral part thereof. The forward piston 900 is located generally toward the mid-portion of the axial extent of the piston rod 746.
The forward piston 900 has a peripheral groove 902 that contains an O-ring 904. The sleeve 882 accommodates the forward piston 900 within a bore 906. The O-ring seal 904 seats against the surface of the bore 906. The sleeve 882 contains a second bore 908 that can be seen in Figure 2 to the left of the forward piston 900. The second bore 908 forms a chamber 910 between the internal surface of the second bore 908 and the external surface of the piston rod 746. The sleeve 882 contains a third bore 912 that permits the piston rod 746 to pass therethrough. The bore 912 contains a groove 914 in which an O-ring 916 is positioned for providing a seal between the sleeve 882 and the piston rod 746. The sleeve 882 contains a groove 918 positioned in its external surface so that an O-ring 920 can be placed therein to effect a seal between the sleeve 882 and the bore 876 of the actuating cylinder 714.

The section of the piston rod 746 located to the right of the forward piston 900, as viewed in Figure 2, has a diameter that is less than the bore 906 of the sleeve 882, forming a chamber 922. The chamber 922 has a bore 924 that is in communication with an elbow fitting 926. In a similar manner, the chamber 910 has a bore 928 that is in communication with an elbow fitting 930. A chamber 931, which is positioned to the right of the rear piston 884, has a bore 932 that is in communication with an elbow fitting 934, and a chamber 936, located to the left of the rear piston 884, is in communication with the second chamber 854 of the master cylinder 712 via the bore 874, the elastomeric tube 738, the elbow 736, a bore 938 in the end cap 772, the reduced diameter bore 778, the threaded lower bore 794, and the viewing tube 730 and its included elbow and tee fittings.

The retaining bushing 744 is supported by the mounting plate 742. The mounting plate 742 is anchored to the front manifold 716 by studs 726 and nuts 728. The retaining bushing 744 has an external part cylindrical section 940 that fits into the axially extending bore 878. The retaining bushing 744 is immobilized by means of a training ring 942 that coacts with a groove 944 in the wall of the axially extending bore 878 in the actuating cylinder 714 with a groove 946 that is milled in the external surface of the part cylindrical section 940.

The operation of the embodiment shown in Figure 14 is similar to that of the preferred embodiment. Figure 14 represents the apparatus in its fully retracted position.
The cycle is actuated by introducing air pressure to the chamber 852 causing the floating reservoir piston 832 to move to the right. The oil to the right of the floating reservoir piston 832 begins to exit the second chamber 854 and travel via the viewing tube 730 and the elastomeric tube 738 into the chamber 936. The increase in volume of oil in the chamber 936 causes the rear piston 884 to move rapidly to the right. As the rear piston moves towards the right, air is exhausted from the chamber 931. Since the forward piston 900 is a part of the piston rod 746, the forward piston 900 also moves to the right, causing an ingress of air into the chamber 910 and an egress of air from the chamber 922. After the initial introduction of air pressure to the chamber 854 at the left of the floating reservoir piston 832, there is a rapid deployment of the piston rod 746 to the right where its travel is halted by interception with a workpiece. The intensification cycle is now ready to begin and since it is clear to one skilled in the art that the cycle is identical to that described in the preferred embodiment, the cycle will not be repeated herein. Once intensification has been accomplished, the device returns back to a rest position by relieving the air pressure in the chamber 856 and applying air pressure in the additional fluid chamber 862 while simultaneously applying air pressure in the chamber 931 to return the hydraulic fluid in the chamber 936 to the chamber 854 and relieving the air pressure in the chamber 852 to allow the floating reservoir piston 832 to return to its initial starting position.

Claims (7)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A load detection device for monitoring the engagement force between a tool and a workpiece, said load detection device comprising:
means for transmitting a force, said means for transmitting a force having a free end, said force being transmitted at said free end;
a load cell having one face juxtaposed said free end of the means for transmitting a force for monitoring said force of said force-transmitting means;
biasing means mounted between said free end and said one face of said load cell, said biasing means providing a biasing force to urge said load cell monitoring said force away from said free end;
a piston rod adapter having a blind bore at one end and an open end opposite said one end, said opposite end being slidably mounted to said free end of said means for transmitting a force, said biasing means and said load cell being mounted in said blind bore of said piston rod adapter and further being interposed between said free end and the bottom of said blind bore; and means for limiting the movement of said means for transmitting a force relative to said piston rod adapter, said limiting means being mounted to said means for transmitting a force such that the force transmitted at said free end of said means for transmitting a force is counteracted by said biasing means, and the net effect of said force is monitored by said load cell to determine the engagement force between said tool and said workpiece.

2. The load detection device of claim 1, wherein said means for limiting the movement of said force-transmitting means relative to said piston rod adapter includes:
an elongated slot diametrically disposed in said piston rod adapter; and a pin mounted to said means for transmitting a force, said pin having ends engaging said slot such that said means for transmitting a force is limited in movement relative to said piston rod adapter.

3. The load detection device of claim 2, wherein said piston rod adapter slidably telescopes over said free end of said means for transmitting a force, said piston rod adapter enclosing said biasing means and said load cell.

4. The load detection device of claim 1, 2 or 3, wherein said piston rod adapter includes a radially-disposed bore for egress of an electrical connection attached to said load cell.

5. The load detection device of any one of claims 1 to 4, including retention means for retaining said piston rod adapter on said free end.

6. The load detection device of any one of claims 1 to 5, wherein said biasing means is a spring, said spring being interposed between said free end and said load cell, said spring transmitting said force between said free end and said load cell.

7. A load detection device for monitoring a tool when engaging and disengaging a workpiece, said load detection device comprising:
a piston rod, said piston rod having a free end, said piston rod transmitting a force at said free end, said piston rod having a diametral aperture located adjacent said free end;
a load cell located adjacent said free end of said piston rod;
a spring interposed between said free end and said load cell, said spring biasing said load cell away from said free end, said spring transmitting said force between said piston rod and said load cell;
a piston rod adapter slidably telescoping over said free end of said piston rod, said piston rod adapter enclosing said load cell and said spring, said piston rod adapter having a pair of diametrally-opposed longitudinal slots disposed thereon, said piston rod adapter having a radially aligned bore for egress of an electrical connection to said load cell; and a pin simultaneously engaging said diametral aperture of said piston rod and said pair of diametrally-opposed longitudinal slots of said piston rod adapter, said pin retaining said piston rod adapter on said piston rod, said pin being capable of traversing said pair of diametrally-opposed longitudinal slots for providing axial movement of said piston rod adapter in relation to said piston rod.