US2929298A - Horizontal double end machine - Google Patents

Description

March 22, 1960 w. P. HILL 2,929,298

HORIZONTAL DOUBLE END MACHINE Filed May 20. 1955 '7 Sheets-Sheet 1 H INVENTOR. x M/Ar )7 #171 BY L I TaFNIf/S March 22, 1960 Filed May 20. 1955 W. P. HILL HQRIZONTAL DOUBLE END MACHINE 7 Sheets-Sheet 2 March 22, 1960 w. P. HILL HORIZONTAL DOUBLE END MACHINE 7 Sheets-Sheet 3 Filed May 20. 1955 INVENTOR. Vl d/z r )7 #27] March 22, 1960 w. P. HILL HORIZONTAL DOUBLE END MACHINE '7 Sheets-Sheet 4 Filed May 20. 1955 INVENTOR. Vl djier ff/i/Z BY $1,414; Em/4 March 22, 1960 w. P. HILL 2,929,298

HORIZONTAL DOUBLE END MACHINE Filed May 20. 1955 '7 Sheets-Sheet 5 l I l l l I l i.. E .5 g A INVENTOR. I vfzr 20/172 exalt/g March 22, 1960 Filed May 20. 1955 w. P. HILL 2,929,298

HORIZONTAL DOUBLE END MACHINE '7 Sheets-Sheet 6 5' ray/vars:

March 22, 1960 w. P. HILL 2,929,298

HORIZONTAL DOUBLE END MACHINE Filed May 20. 1955 7 Sheets-Sheet 7 HORIZGNTAL DOUBLE END MACHINE Walter P. Hill, Bloomfield Hills, Mich.

Application May 20, 1955, Serial No. 509,715

4 (llaims. (Cl. 90-11) This invention relates to a machine for performing work operations simultaneously on opposite ends of a workpiece and more particularly to a high speed, double end machine adapted to perform work operations on workpieces of various lengths and diameters.

It is an object of this invention to provide a high speed double end machine of the aforementioned type which may be easily and quickly adjusted to accommodate work pieces of various lengths and diameters.

It is a further object of this invention to provide a high speed double end machine of the aforementioned type which is adapted to perform a wide variety of double end operations on tubular and solid metal parts, including boring, chamfering, burring, milling, centering, flaring, spinning, and other like operations.

It is a still further object of this invention to provide in a machine of the aforementioned type, an improved magazine or hopper in which a plurality of workpieces may be stacked, and an improved and unique mechanism for automatically feeding the workpieces from the hopper or magazine into a work performing position.

It is a still further object of this invention to provide, in a machine of the aforementioned type, improved and novel means associated with the hopper or magazine for clamping a workpiece in position for the work performw,

ing operation.

It is a still further object of this invention to provide, in a machine of the aforementioned type, uniquely controlled spindles for carrying tools for performing a work operation and an improved mechanism for operating the same.

It is a still further object of this invention to provide a machine of the aforementioned type which is completely automatic in operation and in which the various elements automatically operate in sequence relative to each other to perform the work operation on a plurality of workpieces placed in the hopper or magazine.

it is a still further object of this invention to provide a machine of the aforementioned type, which is exceptionally efficient in operation, rugged in construction, and relatively inexpensive to manufacture.

These and other objects of this invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a front view, partially in section and partially in elevation, of a machine of this invention, with certain of the electric, hydraulic and air system elements eliminated for the purpose of clarity;

Fig. 2 is a top view, partially in section and partially in elevation, of the structure illustrated in Fig. 1;

Fig. 3 is a fragmentary view, partially in section and partially in elevation, taken along the line 3-3 of Fig. 1, and illustrating a workpiece clamped in position for a work performing operation;

Fig. 4 is a view similar to Fig. 3, illustrating the position of the parts of a machine prior to clamping a workpiece in the work performing position;

Fig. 5 is an enlarged view of structure illustrated in Fig. 2, taken within the circle 5 thereon;

Fig. 6 is a fragmentary view, partially in section and partially in elevation, of one of the work tool spindles and its associated operating mechanism;

Fig. 7 is a diagrammatic view of the hydraulic mechanism of the machine of this invention; and

Fig. 8 is a diagrammatic view of the electrical circuit of this invention.

It is often necessary to perform work operations on opposite ends of tubular or solid metal parts. Typical operations which often must be performed on opposite ends of such metal parts are boring, chamfering, burring, milling, centering, flaring and spinning operations. It is, of course, desirable to perform these or similar operations on both ends of the workpiece simultaneously and as rapidly as possible. The machine of this invention is designed to perform such operations simultaneously on opposite ends of tubular and solid workpieces, in an extremely rapid manner, and with the machine of this invention it is possible to perform such operations on more than six thousand workpieces per hour. The machine of this invention likewise has considerable versatility, not only in being able to perform different types of work operations, but inbeing able to accommodate various lengths and diameters of metal parts. For example, the machine illustrated is adapted to handle workpieces of a length from three inches (3") up to forty inches (40"), having diameters from three-sixteenths of an inch 7 to five-eighths of an inch it will, of course, be appreciated that different sized machines may be made to accommodate workpieces of still different lengths and diameters.

Referring now to the drawings, it will be seen that the machine consists of a welded steel base or stationary supporting structure 11, adapted to rest on the floor of a building or the like. Horizontal ways 13 are provided on the top horizontal surface of the base and a pair of spaced apart carriages 15 and 17 are supported on the base 11. The carriage 15 is fixed to the base and is normaily not moved thereon, while the carriage 17 is slidably adjustable toward and away from the carriage 15, and guided for such movement by the ways 13. In order to adjust the position of the carriage 17, a lead screw 19 is rotatably supported in the base and threadably engages a nut, not shown, connected with the carriage. A hand wheel 20 is provided on one end of the lead screw so that its rotation will cause the carriage 17 to move'toward or away from the carriage 15. A magazine or hopper is provided for supporting a plurality of workpieces 18 on which a work performing operation is to be performed, and one half of the hopper or magazine is supported on the carriage 15, while the other half is supported on the carriage 17. In this connection 'it will be noted that a vertical plate 21 is supported on and rigid with each of the carriages 15 and 17, adjacent the inner or adjacent ends thereof. Connected with each of the plates 21 is an angle sectioned hopper guide member 23, one portion 25 of which extends downwardly and forwardly along the plate, and the second portion 27 of which extends vertically downwardly from the portion 25, adjacent the front end thereof. A second angle shaped hopper guide member 29 is connected with each of the hopper plates 21 in spaced relation to the vertical portion 27 of the guide member 23. There is thus provided between the hopper guides 27 and 29 a vertical chute for supporting a plurality of workpieces. The carriage 17 is, of course, moved toward or away from the carriage 15 so that the hopper plates 21 are spaced apart a distance substantially equal to the length of the particular workpieces 18 in the hopper.

elsaaaas members 29 are provided with elongated slots 31 through which fasteners, such as cap screws 33, extend so that by loosening the cap screws the hopper members '29 can be moved toward or away from the hopper guide portion 27 to thus accommodate workpieces 18 of varying diameters. Supported on each of the hopper side plates 21 is a mechanism for permitting only one workpiece 18 at a time to drop from the hopper into clamping means, to be hereinafter described, which support the workpieces for the work performing operations. Each of these mechanisms includes an elongated platelike finger 35 disposed on approximately a thirty degree angle to the horizontal and having a vertical front face 37 which is normally disposed beneath the hopper chute so that the finger engages the lowermost workpiece 18 therein and cooperates with the lower end of the adjacent hopper guide portion 27 to retain the same in the chute as illustrated in Fig. 3. Each finger 35 is slidably supported on its adjacent hopper plate 21 by means of a bracket 39, and the outer or front end of the finger is connected with a head 41. The head 41 is in turn connected with a piston rod 43 which projects from a cylinder 45. A conduit 47 is connected to the outer or forward end of the cylinder and is connected to a suitable source of air pressure, not shown, so as to urge a piston 49 within the cylinder toward the rear of the machine to resiliently retain the finger 35 in the position illustrated in Fig. 3. The finger 35 may, however, be moved forwardly against the air pressure within the cylinder upon the application of force to the end thereof. The piston and cylinder unit thus acts as an air spring to resiliently retain the workpiece 18 in the position illustrated in Fig. 3. The position of the free end of the finger may be adjusted so as to properly engage different sized workpieces by means of an adjusting rod 51 which is threadably connected with the head 41 and extends rearwardly therethrough so as to abut the bracket 39 and control the rearmost position of the finger 35.

A clamping mechanism is disposed below each side of the hopper chute for picking up a workpiece 18 from the hopper and clamping the same in position for the work performing operation. clamping mechanism includes a member 53 which is bolted to each hopper plate 21 below the chute and provided with ways 55 on the upper surface thereof. A carriagelike member 57 is slidably supported on the member 53 for fore and aft movement. Removably secured to the carriage member 57 is a blocklike clamping member 58 which has a semicircular recess 60 in the front face thereof of a diameter slightly less than the diameter of the workpiece 18. This clamp may, of course, be removed or changed to accommodate workpieces of various diameters. In order to actuate the carriages 57, actuating earns 59 and 59 are supported on a splined shaft 61 which extends laterally of the machine and on which the cam 59 is slidable when the carriage 17 is moved laterally of the machine. A link 62 is pivotally connected at one end to the dwell portion of each cam at 65 and at its opposite end at 64 to the adjacent carriage member 57. An adjustable stop screw 67 is supported on the member 53 to limit the movement of the cam in one direction, while an adjustable stop screw 69 is supported on the adjacent hopper plate 21 by a bracket 71 to limit the movement of the cam in the opposite direction, as illustrated in Fig. 4. The spline shaft 61 oscillates so as to oscillate the cam and thus reciprocate the carriage 57 and the clamp block 59 fore and aft between the positions illustrated in Fig. 3 and in Fig. 4.

Referring now to Figs. 2 and 5, it will be noted that the shaft 61 is oscillated by a pair of hydromotors 63 and 63' carried by each of the main carriages 15 and 17. The hy'diomo'tors are of the conventional hydraulic type in which a vane member oscillates, and the operation of the motors will be hereinafter described. The motor 63 carried by the carriage 15 has its output shaft 68 connected with a splined collar which in turn is journalled in antifriction bearings 72. The splined collar, in turn, is splined adjacent its opposite end at 74, to the spline shaft 61 so as to rotate the same. The splined collar 70 is rigidly connected with the cam 59 so that oscillation thereof causes oscillation of the cam 59. The splined shaft 61 extends through the other hydromotor 63 and the vane member of the hydromotor 63 is slidable on the shaft 61. The right hand end of the shaft 61, as viewed in Fig.2, is journalled in and held against longitudinal movement by a portion of the machine base 11. The spline shaft 61 is connected with the cam 59' through a splined collar 70 which is journalled in bearing 72, as previously described. Thus, the hydromotor 63' and its adjacent cam 59', mounted on the carriage 17, can slide laterally relative to the spline shaft 61 without becoming disconnected'therefrom and the hydromotors are operated in sequence with each other to oscillate the shaft 61 and thus move the clamp members 59 and 59 fore and aft in unison.

A complemental workpiece clamp member 73 is rigid- 1y connected with a bracket 75 mounted on each hopper plate 21, forwardly of the adjacent movable clamp 58. The clamp member 73 has a semicircular recess 77 in the 'back face thereof, which is complemental to the recess 61 in the other clamp member 58. The clamp 73 can be removed from the bracket 75 so that a different clamp member can be connected with the bracket 75 to accommodate workpieces of various diameters. lidably supported in each bracket 75 and extending through each clamp member 73 is a platelike finger 79, thefront edge of which is tapered downwardly and forwardly at 81. The back end of each finger 79 is connected to a head 83, which in turn is connected to a piston rod projecting from a cylinder 87 and rigidly connected with a piston 89 disposed therein. A conduit 91 is connected to the front end of the cylinder and the interconnected with the conduit 47 of thecylinder 45 so as to provide air pressure yieldably urging piston 89 rearwardly and urging the 7 finger 79 rearwardly. The finger 79 can, however, be

In this connection, each its moved forwardly or away from the hopper chute by the application of pressure thereto so that the piston and cylinder unit acts as a tension spring for resiliently urging the finger 79 'rearwardly. The head 83 likewise carries an adjsuting rod 86 which is engageable with the bracket 75 for limiting the rearward movement of the finger 79. The rod 85 can be adjusted to adjust the rearj most position of the finger 79 in accordance with the diameter of the workpieces.

In order to position a workpiece in the proper position for the work performing operation, the clamp elements 58 are disposed in the position illustrated in Fig. 4 and when the cams 59 and 59' are oscillated or rotate counterclockwise; the clamp elements, which have a projecting plate 95 immediately below the recess 61 therein, move forwardly carrying a workpiece resting upon the platelike projections 95. This forward movement of the clamps 58 moves the'fingers 35 forwardly away from the hopper chute to permit the next workpiece to drop down onto the top of the clamp 58, asillustrated in Fig. 3. As the clamps58 move forwardly the fingers 79 are moved rearwardly against the air pressure in'the cylinders 3'7 and retain the workpiece on theclamp 58 until the workpiece is firmlyheld between the clamp members 58 and 73. The work performing operation, which will be hereinafter described, is then performed, and the cams 59 and 59' then oscillate in a clockwise direction to move the clamping members 58 rearwardly.

As the clamping members 58 move rearwardly, the fingers 35 will insure that the workpiece will be pushed 01f of the front edge of the platelike proejctions 95 on the clamp members and the workpiece will drop onto a chute therebelow teased by angle members 98 carried .byeach hopper plate 21.

As soon as the clamp members return to their fully retracted position, the workpiece which has been resting thereon will drop down onto the projections 95 and a subsequent clamping operaation will occur when the clamp member moves forwardly.

In order to perform the work operations simultaneously on the opposite ends of a workpiece held in the clamped position as described above, a pair of opposed rotatable spindles 97, each of which is adapted to carry a work performing tool, are rotatably and axially movably supported on the carriages and 17. in this connection a cagelike housing 99 is supported on each carriage. Extending through the center of each cagelike housing 39 is a sleeve 101 in the right hand portion of which a sleeve 103 is movably supported for sliding movement laterally of the machine. The spindle 97 is rotatably supported in the sleeve 183 by suitable bearings 107 and the left hand end of the spindle, as viewed in Fig. 6, is splined at 103. An internally splined sleeve 111 is disposed on the spline end of the spindle and rotatably supported in the sleeve 101 by bearings 113. A pulley 115 is keyed to the sleeve 111 outwardly of each housing 99. Each pulley 115 is operativeiy connected by belt 116 to a pulley 117 on the output shaft 119 of an electric motor 121, which is supported on the top of each housing 99. A pair of opposed hydraulic piston and cylinder units 123 are disposed in each housing 99. A piston rod 125 projects from each piston and cylinder unit through the inner wall of the housing 99 and is connected to a head 127, which in turn is rigid with the sleeve 103. The piston and cylinder units are actuated, as will be hereinafter described, and when the piston rods are moved to their extended position the spindle 97 and sleeve 103 move inwardly to move the carriage and a tool carried thereby into engagement with the end of a workpiece. Each spindle is rotatably driven by its motor 121 through the belt and pulleys, and the spindle is free to move longitudinally relative to the pulley 115 because of the spline connection previously described. Thus, after each workpiece has been clamped in position, the rotating spindles carrying the working tool move upwardly to perform the work operation and then are retracted so that the workpiece can be discharged from the machine and a new workpiece moved into the clamping position.

Referring now to Fig. 7, which is a diagrammatic view of the hydraulic system, it will be seen that a suitable pressure source such as a pump and reservoir 131 is provided, which pumps liquid under pressure through conduit 133 to a solenoid operated valve 135, valve 135 includes solenoids S1 and S2 which are actuated in a manner which will be hereinafter described. In order to move the spindles inwardly solenoid S1 is actuated, which shifts the valve so that liquid under pressure flows through conduits 137 and 139 to the piston and cylinder units 123 so as to move the pistons and piston rods inwardly and thus move the work tool into engagement with the workpiece. Fluid in the opposite end of the cylinders flows through conduit 141, throttling valve 143, conduit 145, back through the valve 135 and to tank through conduit 147. When it is desired to retract the work engaging tools solenoid S2 is energized, as will be hereinafter described, so that liquid under pressure flows through conduits 145 and 141 to the opposite end of cylinders 123, while the fluid in the other ends of the cylinders flows through conduits 139 and 137, valve 135 and conduit 133, back to tank. Fluid flowing under pressure through conduit 133 likewise flows through conduit 151 to a solenoid operated valve 153 which is actuated by solenoids S3 and S4.

When it is desired to oscillate the hydromotors in a counterclockwise direction, solenoid S3 is energized, which shifts the valve 153 so that fluid flows through conduits 155 and 157 to the hydromotors and to one side of the vane therein. Fluid on the opposite side of the vane flows back to tank through conduits 159, 161, valve 153 and motors. .also operate contacts M1, M2 and M3 which are conconduit 163. When it isdesired to oscillate thethyd-romotors in a clockwise direction, solenoid S4 is energized,

as will be hereinafter described, and fluid flows into conduit 151, through the valve 153 to conduit 161, thence through conduit 153 to the hydromotor, while fluid returns from the opposite side of the hydromotor, through conduits 157 and 155, valve 153 and conduit 163.

Referring now to Fig. 8, which is a diagrammatic illus- V tration of the electrical operating circuit of the machine, the complete operation of the machine will become apparent. As can be seen therein, the spindle motors 121, as well as a hydraulic pump motor 171, are individually fused three phase motors which are connectible to a three phase source 173, through a three pole single throw switch SW1 and through individual sets of contactors M2, M3, and M1 respectively. These sets of contactors are in turn controlled by the relays MR2, MR3 and MR1.

Each of the electric motors is also provided with an overload switch individual thereto, these switches being labeled OL2, 0L3 and 0L1, respectively.

Single phase power is applied through the control transformer to the fuses F1 and F2. Since the stop switch PB2 is normally closed, upon the operation of the start switch PR1, current passes through the closed start switch, through the normally closed stop'switch, through the windings of relays MR1, MR2 and MR3 in parallel, and through the normally closed overload switches 0L1, 0L2 and 0L3, thereby operating the three relays MRl, MR2 and MR3 to start the operation of the aforesaid three Relays MR1, MR2 and MR3, in operating,

nected in series with one another and in shunt of the start switch so that once the start switch is momentarily depressedthe three motors will continue to be energized until the stop switch'is momentarily depressed unless any .one of the three motors is subjected to an overload condition, in which case one of the three overload switches will be operated resulting in all three of the motors becoming deenerg'ized.

Nothing further will occur until one of the cycle-start switches P133 or PBS are momentarily closed, at which.

time current will flow through the normally closed cyclestop switch PBd, through the momentarily closed cyclestart switch, and through the winding of relay CR1. to operate relay CR1.', Relay CR1, in operating, will close its clamped position, limit switch LS6, which is actuated by the clamp, is closed to operate relay CR5. Therefore,

upon the operation of relay CR1, a path is completed through the closed switches LS1 and LS2, through front cont ct CR5 of operated relay CR5, through contact CR1, and through the winding of relay CR2, to operate relay CR2. Relay CR2 locks operated through its front locking path therefor.

contact CR2 and through a back contact of relay CR3. Relay CR2. in operating, also completes a circuit for the operation of solenoid S3. This causes actuation of valve 153 and counterclockwise movement of the hydromotors, to cause the clamps 58 to clamp a workpiece against the stationary clamps 73. After the workpiece has been clamped switch LS6 is operated to release relay CR5. Despite the release of relay CR5, relay CR2 remains operated due to the existence of the previously traced Clamping of the workpiece also results in the closure of the switch LS3, which is engaged by the clamp to complete a circuit through the front contact CR2 of the operated relay CR2 and the windings of the solenoid LS1 to cause the valve to be actuated so that liquid flows to the piston and cylinder units 123 .to cause the spindles, 97 to move toward the part to be worked on. As the spindles move forwardly limit switches LS1 and LS2 are opened, which produces no immediate effect since relay CR2 is locked over the previously traced path. When both spindles, with their tools mounted'thereon, reach their fully extended position for engagement with the workpieces, switches LS4 and LS5, which are actuated thereby, are closed to operate relay CR3. Relay CR3, in operating, opens its back contact to interrupt the previously traced locking path in relay CR2, whereupon relay CR2 de-energizes both solenoids S1 and S3. Relay CR3 then energizes solenoid S2, which causes the hydraulic liquid to flow through the four-way valve 135 so as to cause the piston rods 125 of the piston and cylinder units 123 to retract. The operation of relay CR3 also results in the completion of a circuit to energize relay CR4. Since this energizing circuit for relay CR4 must include the closed switches LS4 and LS5, the

system timing is arranged so that switches LS4 and LS5 do not open for at least a few milliseconds after the energization of solenoid S2 to permit relay CR4 to operate.

Once relay'CR4 is operated it completes a locking circuit fo'r'itself through its own front contact and through a back contact of relay CR5. When limit switches LS4 and LS5 do open, relay CR3 is released to de-energize solenoid LS2, but relay CR4 remains operated due to the existence of the above described locking path.

When both spindles 97 are completely retracted, limit switches LS1 and LS2 are again closed to complete a path through front contact CR4 of relay CR4 to energize solenoid S4 of valve 155. Hydraulic liquid then flows to the hydromotors to cause the same to rotate in a clockwise direction and retract the clamps 58, whereupon the workpiece on which the operation has been performed will be discharged from the clamp and will roll down the ramp 98. As the workpiece becomes unclamped limit switch LS3, opens in preparation for the next cycle, and limit switch LS6 is closed to operate: limit switch CR5. Relay CR5, in operating, opens its back contact CR5 to interrupt the previously traced locking circuit for relay CR4, whereupon relay CR4 is released and solenoid S4 is subsequently de-energized. Since limit switches LS1 and LS2 are again closed, and since relay CR5 is again operated, the initial conditions are re-established so that the cycle will repeat and will continue to repeat as long as relay CR1 continues to be operated. Momentary depression of the cycle stop switch PB4 will result in the de-energization of relay CR4 so that thereafter the three motors 121 and 171 will continue to rotate, but the operating cycle will not be repeated.

It 'will also be noted that the cycle stop switch PB4 is not immediately operated to stop the operation of the apparatus. If it is depressed during the course of a cycle that cycle will be completed before the apparatus ceases further to function.

Two emergency return switches PB6 and P87 are provided. If either is depressed relay CR1 will be deenergized to prevent the commencement of a succeeding cycle. Additionally relay CR3 will be immediately energized to operate solenoids S2 and S4 in the manner above described. It will be noted that relay CR3 in operating, opens its back contact to release relay CR2 and hence to de-energize solenoids S1 and S3 if they were energized at the time at-which the emergency return switches P36 and P137 were opened. The three motors 121 and 171 will continue to rotate until the stop switch P32 is depressed.

It will thus be appreciated that the machine of this invention operates automatically to perform simultaneously work operations on both ends of a workpiece and that the workpieces are automatically moved into position for the work engaging operation and discharged therefrom automatically and in a rapid manner, so that the machine will have the high production rate previously mentioned.

What is claimed is:

1. In a machine for performing a work operation on a workpiece, means for feeding and supporting a workpiece in position for a work engaging operation, said means including a hopper, a movable clamping element disposed below said hopper in position to receive and support a workpiece when in its retracted position, supporting structure, said movable clamping element being carried by said supporting structure, means for reciprocating said movable clamping element between a retracted position and an extended position, a stationary clamp element for engaging a workpiece when said movable clamp element is in its extended position, whereby said clamp elements cooperate to support a workpiece in a predetermined position for a working operation,'fiexibly actuated finger means supported on said supporting structure for retaining additional workpieces in said hopper until said movable clamping element has again been retracted and for stripping a workpiece from said clamping element during its retraction.

2. In a machine for performing a work operation on a workpiece, means for feeding and supporting a workpiece in position for a work engaging operation, said means including a hopper, a movable clamping element disposed below said hopper in position to receive and support a workpiece when in its retracted position, said movable clamping element being carried by said supporting structure, means for reciprocating said movable clamping element between a retracted position and an extended position, yieldable finger means adjacent said movable clamping element for retaining a workpiece in engagement therewith when said movable clamping element is 7 moved from its retracted position to its extended position,

a stationary complemental clamp element for engaging a workpiece when said movable clamp element is in its extended position, whereby said clamping elements cooperate to support a workpiece in a predetermined position for a working operation and flexibly actuated finger means adjacent said movable clamping element for retaining additional workpieces in said hopper until said movable clamping element has again been retracted and for stripping a workpiece from said clamping element during its retraction.

3. In a machine for performing a work operation on a workpiece, means for feeding and supporting the workpiece in position for a work-engaging operation, said means including a hopper, a movable clamping element disposed below said hopper in position to receive and support a workpiece when in its retracted position, supporting structure, said movable clamping means being carried by said supporting structure, means for reciprocating said movable clamping element between a retracted position and an extended position. a stationary clamp element mounted on said supporting structure for engaging a workpiece when said movable clamping element is in its extended position, whereby said clamp elements cooperate to support a workpiece in a predetermined position for a working operation, a horizontally disposed yieldable finger means mounted on said supporting structure adiacent to said movable clamping element for retaining a workpiece in engagement with the movable clamping element as it advances toward and away from said stationary clamp element, and an angularly disposed yieldable finger means mounted on said supporting structure above said horizontal finger means and having a vertical front edge disposed adjacent to said movable supporting structure, a movable clamping element on said supporting structure disposed below said hopper, said movable clamping element having an upwardly presenting supporting surface for supporting workpieces and a laterally presenting substantially semicircular recess, means for reciprocating said movable clamping element between a retracted position wherein a workpiece can be disposed on said supporting surface to an extended position, a stationary clamping element mounted on said supporting structure having a substantially semicircular recess for cooperating with the semicircular recess of said movable clamping element for clamping a workpiece when said movable clamping element is in its extended position, a horizontally disposed yieldable finger mounted on said supporting structure adjacent to said movable clamping element for retaining a workpiece in engagement with the semicircular recess thereof as it advances toward and away from said stationary clamping element, and an angularly disposed yieldable finger mounted on said supporting structure above said horizontal finger having a vertical front edge disposed adjacent to said movable clamping element in the retracted position of the movable clamping element for initially preventing movement of a workpiece in a direction away from said semicircular recess and for interfering with the movement of a workpiece by said horizontal finger during the retraction of said movable clamping element in a manner to positively eject a workpiece downwardly.

References Cited in the file of this patent UNITED STATES PATENTS 2,235,083 Poole Mar. 18, 1941 2,347,175 Dewey Apr. 25, 1944 2,404,161 Bower July 16, 1946 2,411,110 Pruitt Nov. 12, 1946 2,438,600 Bower Mar. 30, 1948 2,531,395 Carlson Nov. 28, 1950 2,539,723 Branch Jan. 30, 1951 2,622,488 Payne Dec. 23, 1952

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