US3456814A - Transfer assembly for presses - Google Patents

Description

TRANSFER ASSEMBLY FOR PRESSES Filed Oct. 16. 1967 5 Sheets-Sheet 2 a 23 77/7 g5 Z4 55 77 J07 65 30 554 I I I l //1/l /V7"0/?. FREDEP/CK H. 8/44/72 1 W Ti 5 July 22, 1969 F. H. BAUTZ TRANSFER ASSEMBLY FOR PRESSES 5 Sheets-Sheet 5 Filed Oct. 16, 1967 July 22, 1969 F. H. BAUTZ 3,456,814

TRANSFER ASSEMBLY FOR PRESSES Filed Oct. 16, 196'? 5 Sheets-Sheet 4 N g R4 w \kko iii!!! 4;. I 2 w l i 5 :3 m 3 1 m g F N wvavrae.

AWMW July 22, 1969 BAUTZ 3,456,814

I TRANSFER ASSEMBLY FOR PRESSES Filed Oct. 16, 1967 5 Sheets-Sheet 5 I am/ W "H3 5 3,456,814 TRANSFER ASSEMBLY FOR PRESSES Frederick H. Bautz, Hazel Crest, Ill., assignor to Verson Allsteel Press Company, Chicago, Ill., a corporation of Delaware Filed Oct. 16, 1967, Ser. No. 675,543 Int. Cl. B66c 23/10 US. Cl. 214-1 15 Claims ABSTRACT OF THE DISCLOSURE A transfer assembly is provided for a press for gripping and transferring work pieces from station to station along the press. It includes at least one longitudinally movable feed bar and at least one gripper mechanism carried by said at least one feed bar for longitudinally moving gripper finger mechanisms having gripper fingers to grip and release the work pieces for transferring the work pieces as said at least one feed bar is longitudinally moved. The gripper mechanisms laterally advance and retract the gripper finger mechanisms and open and close the gripper fingers thereof. Said at least one feed bar is also raised and lowered by a lifter mechanism. In operation, the feed bars are in their lowered position, and the gripper finger mechanisms are then laterally advanced and the fingers are closed to grip the work piece. The feed bars and gripper finger mechanisms are then raised, longitudinally moved in one direction and then lowered to transfer the work piece from one station to the next. The gripper fingers are then opened and the gripper finger mechanisms are then laterally retracted and longitudinally returned in the opposite direction by the lowered feed bar for another cycle of operation. The lifter mechanisms support the feed bars at a plurality of points along the length thereof.

A principal object of this invention is to provide improved lifter mechanisms in the foregoing transfer as sembly for lowering and raising the longitudinally movable feed bars. Briefly, in this connection, each lifter mechanism includes a lifter housing carried by the press, a plunger vertically slidably mounted in the housing and extending upwardly therefrom, and a bracket carried by the upper end of the plunger and having supporting and guiding rollers thereon. The longitudinally movable feed bars are provided with guide tracks which are engageable with said supporting and guiding rollers to be supported thereby. Means are provided for raising and lowering the plunger for raising and lowering the feed bars. The raising and lowering means may be gear and rack means as specifically disclosed herein. Means are also provided for supplying air under pressure below the plungers so that much of the load carried by the plungers (the feed bars, the gripper mechanisms, the gripper finger mecha nisms, and the Work pieces) is supported by such air under pressure. Such a lifter mechanism, the details of which are disclosed herein, is particularly suitable for use in the transfer assembly disclosed herein, it being simple in construction and accurate in operation and it being rugged for long life operation.

Other objects of this invention reside in the combination of the transfer assembly incorporating the aforementioned lifter mechanisms and including means for operating the lifter mechanisms, means for longitudinally moving the feed bars in one direction and the opposite direction, and means for operating the gripper mechanisms to advance and retract the gripper finger mechanisms and to open and close the gripper fingers thereof all in timed relation.

The specific gripper mechanisms for laterally advancing and retracting the gripper finger mechanisms and for States Patent 3,456,814 Patented July 22, 1969 closing and opening the gripper fingers thereof is disclosed and claimed in Frederick H. Bautz and Howard J. Mc- Elroy application Ser. No. 675,625 filed Oct. 16, 1967. The specific gripper finger mechanisms for gripping and releasing the work pieces are disclosed and claimed in Frederick H. Bautz and Tsuruo Otsuka application Ser. No. 675,544, filed Oct. 16, 1967.

Further objects and advantages of this invention will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawings in which:

FIG. 1 is a diagrammatic front elevational view of a conventional mechanical press having the transfer assembly of this invention applied thereto;

FIG. 2 is a diagrammatic horizontal sectional view through the press of FIG. 1 taken substantially along the line 22 of FIG. 1;

FIG. 3 is a chart illustrating the motions applied to the gripper finger mechanisms of the transfer assembly for transferring work pieces from one station to the next station in the press;

FIG. 4 is a top plan view of one portion of the transfer assembly diagrammatically illustrated in FIG. 2;

FIG. 5 is an elevational view of one portion of the transfer assembly illustrated in FIG. 1;

FIG. 6 is an elevational 'view of a portion of the transfer assembly illustrated in FIG. 5 with parts of the lifter mechanism shown in section;

FIG. 7 is an endelevational view of a portion of the transfer assembly looking from the right of FIG. 6 with the lifter mechanism thereof in section along the line 77 of FIG. 6;

FIG. 8 is a vertical sectional view through the gripper mechanism of a portion of the transfer assembly taken substantially along the line 8-8 of FIG. 6;

FIG. 9 is a horizontal sectional view through the gripper mechanism taken substantially along the line 9-9 of FIG. 8;

FIG. 10 is a vertical sectional view through the gripper mechanism taken substantially along the line 1010 of FIG. 8;

FIG. 11 is a horizontal sectional view through the gripper mechanism taken substantially along the line 11-11 of FIG. 9 and illustrating the actuator rods in the retracted position;

FIG. 12 is a horizontal sectional view similar to FIG. 11 but illustrating the actuator rods advanced to substantially the advanced position;

FIG. 13 is a horizontal sectional view similar to FIGS. 11 and 12 but illustrating the second actuator rod being advanced beyond the advanced position toward the projected position; and

FIG. 14 is an elevational view of a splined ring utilized in securing the gripper finger mechanism to the gripper mechanism.

Referring first to FIGS. 1 and 2, a conventional press, such as a mechanical press, is diagrammatically illustrated at 10. It includes a bed 11, uprights 12 supporting a crown (not shown) and a vertically reciprocatable ram 13 which may be driven from a power driven crankshaft (not shown). Arranged along the length of the bed 11 is a plurality of spaced apart work forming stations, each including a die structure 14 carried by an adapter plate 11A and bolster on the bed 11 and a punch structure 15 including an adapter plate carried by the ram 13 for performing work functions on work pieces upon each downward stroke of the press ram 13 as they are progressively advanced along the press 10 from station to station. The initial work pieces are fed to the press 10 from a magazine 16 at one end of the press and the finished work pieces are discharged from the press 10 by a discharge mechanism 17, such as a conveyor or a chute or the like,

at the other end of the press 10. The work pieces are progressively transferred from station to station in the press from the magazine 16 to the discharge mechanism 17.

The press is provided with a transfer assembly generally designated at 18 and extending lengthwise of the press. The transfer assembly 18 includes at least one longitudinally movable feed bar 19 (two being illustrated with one toward the front of the press and the other toward the rear of the press) which carry a plurality of equally spaced gripper mechanisms 20. Each gripper mechanism 20 laterally advances and retracts a gripper finger mechanism 21 and opens and closes the gripper fingers of the gripper finger mechanism for gripping and releasing the Work pieces being formed by the press. The transfer assembly 18 also includes a plurality of lifter mechanisms 22 carried by the adapter plate 11A on the bed 11 for supporting and raising and lowering the longitudinally movable feed bars 19.

A pair of longitudinally extending reciprocatable rods 23 is provided for longitudinally moving the feed bars 19 in one direction and in the opposite direction. A pair of longitudinally extending reciprocatable rods 24 is provided for operating the gripper mechanisms 20 to advance and retract the gripper finger mechanisms 21 and to open and close the gripper fingers thereof. A pair of longitudinally extending reciprocatable rods 25 is provided for operating the lifter mechanisms 22 to raise and lower the feed bars 19 and hence the gripper mechanisms 20 carried thereby. A suitable drive mechanism 26, which is operated from the crankshaft of the press 10 in timed relation therewith, is arranged at one end of the press 10 for reciprocating the rods 23, 24 and 25 in timed relation to each other and to the upward and downward movement of the press ram 13.

The motions imparted to the gripper finger mechanisms 21 for transferring the work pieces from the magazine 16 and progressively from station to station along the press 10 to the discharge mechanism 17 are diagrammatically illustrated in FIG. 3. With the parts in the positions illustrated in FIGS. 1 and 2, the ram 13 has been raised sufficiently so that the punches carried thereby are clear from the work pieces, the feed bars 19 are in their lowered and their returned positions, and the gripper fiinger mechanisms 21 are in their retracted positions with their fingers opened. This is represented by the point A in the diagram of FIG. 3.

First, the rods 24 are moved to the left with respect to the feed bars 19 to advance laterally the gripper finger mechanisms and close the fingers thereof to grip the work piece in that station. Next, the rods are moved to the left to raise the feed bars 19 and hence the gripper finger mechanisms 20 to lift the gripped work piece from the die structure of that station. Next, the rods 23 and 24 are simultaneously moved to the left to move the raised feed bars 19 to the left to transfer the gripped and raised work piece from that station to the next station, there being no relative movement between the rods 23 and 24 during this movement. Next, the rods 25 are moved in the opposite direction to the right to lower the feed bars 19 and hence the gripper finger mechanisms 20 for lowering the gripped work piece into the die structure 14 of said next station. Next, the rods 24 are moved in the opposite direction to the right to open the gripper fingers in the gripper mechanisms 20 and retract the gripper finger mechanisms. Next, the rods 23 and 24 are simultaneously moved in the opposite direction to the right to move the lowered feed bars 19 to the right to return the gripper finger mechanisms 21 with their fingers in opened position to point A in FIG. 3 for another transferring cycle. The punches 15 on the ram 13 perform their workfunctions on the work pieces While the gripper finger mechanisms 20 are lowered and retracted. The drive mechanism 26 may include suitable cam linkage and lever constructions operated from the crankshaft of the press 10 for producing the foregoing timed sequences of operation of the 4 rods 23, 24 and 25 with respect to the operation of the press ram 13.

While the transfer assembly 18 is illustrated in FIGS. 1 to 3 as having two sets of mechanisms, one toward the front of the press and the other toward the rear, for gripping the work pieces at two points for transferring them along the press, in some instances it may be desirable to grip the work pieces at only one point for this purpose and, under such circumstances, only one set of mechanisms need be used, as for example, the one toward the front of the press or the one toward the rear thereof. The constructions of the lifter mechanisms 22 and the gripper mechanisms 20 are generally illustrated in FIGS. 4 to 7, the details of the lifter mechanisms 22 being illustrated in FIGS. 6 and 7 and the details of the gripper mechanisms being illustrated in FIGS. 8 to 13.

Referring now to FIGS. 4 to 7 the lifter mechanism, generally designated at 22, includes a lifter housing 30' which is suitably secured to the top of the adapter plate 11A on the bed structure 11. It has a downwardly extending projection 31 which is accommodated by an opening 32 in the adapter plate 11A. The adapter plate 11A in addition to carrying the lifter housing 30 also carries the die structures 14 so that the transfer assembly 18 and the die structures 14 are a unitized assembly which may be removed and replaced as a unit, the adapter plate being removable from the bolster and the bed 11 for this purpose. The housing 31 has a vertically arranged cylindrical opening 33 therethrough and a bearing sleeve 34 is arranged at the top of the opening and a bearing sleeve 35 is arranged toward the bottom of the opening but spaced upwardly therefrom. The opening 33 is closed at its bottom by a plate 36 suitably secured to the downward extension 31 of the housing 30. A plunger 37 is vertically slidably mounted by the bearing sleeves 34 and 35 in the opening 33 and it is provided at its upper extremity with a flange 38. Adjacent its lower end the plunger 37 is provided with a seal 39 for sealing the plunger with respect to the bearing sleeve 35.

A- bracket 41 is secured to the flange 38 at the upper end of the plunger 37 and this bracket 41 carries four rollers 42 rotatable about vertical axes, two rollers 43 rotatable about horizontal axes and two rollers 44 rotatable about horizontal axes. These rollers cooperate with a track 45 secured to the underside of the longitudinally movable feed bars 19. The track 45 extends laterally from the feed bars 19 so as to be laterally engaged by the rollers 42 and vertically engaged by the rollers 43 and 44. As a result, the track 45 and, hence, the feed bars 19 are supported and guided for longitudinal movement by the rollers 42, 43 and 44 carried by the upper end of the plunger 37.

The vertically movable plunger 37 is provided on one side with a toothed rack 47 which is engaged by an elongated gear 48, substantially one half of the gear 48 being a driven gear meshing with the toothed rack 47 on the plunger 37. The other half of the gear 48 forms a driving gear. The gear 48 is journaled in suitable bearings 49 carried by the housing 30 and they and the gear 48 are enclosed by plates 50 suitably secured in place. Rack teeth 51 on a longitudinally movable rack 52 mesh with the driving gear portion of the gear 48. The exterior of the rack 52 is splined to engage internal splines on spline bearings 54 suitably secured in a longitudinally extending opening 53 in the housing 30 to prevent rotation of the rack. The splined rack 52 is secured by suitable adjustable couplings 55 to the longitudinally movable rod 25. Where two feed bars 19 are used, a longitudinally movable rod 25 is provided for each row of lifter mechanisms. Both rods 25 are driven from a common cam drive and are thus actuated simultaneously.

With the parts of the lifter mechanism in the position illustrated in FIGS. 4 to 7, the plunger 37 is in its lowered position and, hence, the feed bar 19 is in its lowered position. When the rack 52 is moved to the left by the longitudinally reciprocatable rod 25, the driving portion of the gear 48 is rotated in a clockwise direction as illustrated in FIG. 6 to cause the driven portion of the gear 48 to raise the plunger 37 and, hence, the feed bar 19 supported by the supporting and guide rollers 42, 43 and 44 carried by the bracket 41 which is secured to the upper end of the plunger 37. When the rack 52 is moved in the opposite direction to the right by the longitudinally reciprocatable rod 25, the gear 48 is rotated in the counterclockwise direction to lower the plunger 37 and, hence, the feed bar 19. Thus, by longitudinally reciprocating the rack 52 in one direction and the opposite direction the feed bar 19 is raised and lowered, the longitudinal reciprocation of the rack 52 being accomplished by the longitudinal reciprocation of the rod 25.

A manifold 56, to which compressed air is suitably supplied, extends along the length of the press adjacent the various lifter mechanisms 22 and suitable connections 57 are made from this manifold 56 to a passage 58 in the downwardly extending portion 31 of the lifter housing 30 for supplying compressed air below the sleeve 31 under the plunger 37. This compressed air normally exerts an upward force on the plunger 37 for supporting much of the load of the feed bar 19 and the mechanisms carried thereby. As a result, minimum stress is applied to the rack 52, the gear 48 and the toothed rack 47 of the plunger 37 and ready raising and lowering of the feed bar 19 and the mechanisms carried thereby is provided with minimum force applied to the longitudinally reciprocatable rod 25. By adjusting the adjustable connections 55, the positions of the rack 52 and, hence, the plunger 37 may be adjusted with respect to the position of the longitudinally reciprocatable rod 25. The stroke length of the reciprocatable rod 25 may be infinitely adjustable within a predetermined range so that the amount of lift motion may be varied to suit the requirements of the parts to be produced. The number of lifter mechanisms may be selected to suit the length of the feed bars 19 and the racks 52 thereof may be connected together by the threaded couplings 55.

The gripper mechanism generally designated at 20 in FIGS. 4 to 13 includes a gripper mechanism housing 62. This housing 62, as illustrated in FIGS. 8 to 13, includes a transversely extending opening 63 in which internally splined bearing members 64 are mounted. Slidably mounted in these bearing members 64 is an externally splined hollow first actuator rod 65, the splines permitting longitudinal sliding movement of the first actuator rod 65 but preventing rotation thereof. A side of the hollow first actuator rod 65 is milled out as indicated at 66 and one side of this milled portion 66 of the hollow actuator rod 65 is provided with rack teeth 67. The other side of said side of the hollow actuator rod 65, which is also milled out as indicated at 8, provides a circular cam slot which in turn is provided with a recess 69 and a shoulder 70 in the form of a modified involute. A second actuator rod 71 is longitudinally slidable in the hollow first actuator rod 65 and it is provided with rack teeth 72 which extend to a greater length to the left than the rack teeth 67 in the first actuator rod 65. The end of the second actuator rod 71 has an annular shoulder 73 which is adapted to engage the corresponding end of the first actuator rod 65 when said actuator rods are in their retracted and advanced positions. The second actuator rod 71 is provided with an extension 74 beyond the shoulder 73 for operating the fingers of the gripper finger assembly 21.

A vertically arranged pin 76 is supported in the gripper mechanism housing 62 by the bottom wall thereof and by a cover 77 suitably secured in place on the housing 62, a key holding the pin from longitudinal and rotative movement. A combination gear and cam member 78 is rotatably mounted on the pin 76 by suitable bearings. The combination gear and cam member 78 has a driving gear 79, a driven gear 80 and a cam 81. A rack 83 is longitudinally slidably mounted in the housing 62 and it is provided with rack teeth 84 which mesh with the driving gear teeth 79. The rack 83 is longitudinally provided with a hole for receiving the longitudinally reciprocatable rod 24 and is adjustably connected along the rod 24 by nuts 85 threaded on the rod 24. Thus, as the rod 24 is reciprocated, the rack 83 drives the driving gear 79. The rack 83 is adjustably mounted on the rod 24 so that each gripper mechanism may be adjusted and set independently of all others. Thus, adjustment of one gripper mechanism will not affect the setting of others.

With the parts in the position illustrated in FIGS. 4 to 11, the longitudinally reciprocatable rod 24 and rack 83 are in the right hand position and the first actuator rod and the second actuator rod 71 are in the retracted position. As the longitudinally reciprocatable rod 24 is moved to the left, the driving gear 79 is rotated by the rack 83 to rotate the driven gear 80 and the cam 81. This rotation of the driven gear 80 which meshes with the racks 67 and 72 on the actuator rods 65 and 71 laterally advances these actuator rods from their retracted poSitions as illustrated in FIG. 11 to substantially their advanced positions as illustrated in FIG. 12. When the actuator rods 65 and 71 are so moved to substantially their advanced positions as illustrated in FIG. 12, the rack teeth 67 on the first actuator rod 65 disengaging the driven gear teeth 80 so that the first actuator rod 65 cannot be advanced any further thereby. At this point the leading edge of the cam '81 having a modified involute form engages the shoulder of modified involute form in the recess 69 of the cam slot 68 in the first actuator rod 65 to provide a slight amount of additional forward motion to the first actuator rod 65. When, however, the leading edge of the cam 81 disengages the shoulder 70 as illustrated in FIG. 13, the cam 81 is engaged by the circular cam slot 68 in the actuator rod 65 and, hence, further advance of the first actuator rod 65 is stopped, the cam 81 cooperating with the circular cam slot 68 to lock the first actuator rod 65 in the advanced position. As the combination cam and gear member 78 is further rotated, the driven gear which is still in mesh with the rack teeth 72 on the second actuator rod 71, causes continued advance of the second actuator rod 71 toward a projected position. Such continued advancing movement of the second actuator rod 71 beyond the advanced position to the projected position operates to cause the fingers of the gripper fingers mechanism 21 to close as will be explained more fully hereafter.

When the longitudinally reciprocatable rod 24 is moved in the opposite direction to the right, the combination gear and cam member 78 is rotated in the opposite direction to retract the second actuator rod 71 from its projected position to its advanced position. When the second actuator rod is thus retracted to its advanced position, the leading edge of the cam 81 is returned beyond the shoulder 70 in the slot 69 in the first actuator rod 65 and the shoulder 73 on the first actuator rod 71 engages the end of the first actuator rod 62. This causes the first actuator rod 65 to be retracted somewhat from its advanced position so that the rack teeth 67 thereof are re-engaged by the driven gear 80 to positively drive the first actuator rod 65 and also the second actuator rod 71 from their advanced positions to their retracted positions as illustrated in FIG. 11. When the first actuator rod 65 is being initially retracted, the modified involute leading edge of the cam 81 and the modified involute shoulder 70 on the rod 65 engage to insure proper reengagement of the rack teeth 67 With the teeth of the driven gear 80. Thus, upon movement of the longitudinally reciprocatable rod 24 to the left, the first and second actuator rods 65 and 71 are driven to their advanced position from their retracted position, the first actuator rod 65 is stopped or locked in its advanced position and the second actuator rod 71 is advanced beyond the advanced position to the projected position. Upon movement of the longitudinally reciprocatable rod 24 in the opposite direction to the right the second actuator rod 71 is retracted from its projected position to its advanced position, the stopping or locking means for the second actuator rod 71 is released and both the first actuator rod 65 and the second actuator rod 71 are retracted from their advanced position to their retracted position.

The gripper finger mechanism generally designated at 21 in FIGS. 7, 8, 9, 11 and 12 includes a bracket 87 which fits over the splined end of the first actuator rod 65. Adjacent its end, the first actuator rod 65 is provided with a first groove for receiving a snap ring 89 and a second wider groove for rotatably receiving an internally splined ring 88 (FIG. 14). The ring 88 is drawn against the snap ring by three equally radially spaced screws threaded into the bracket 87 to clamp the bracket 87 in place, and when this occurs the internal splines in the ring 88 engage the external splines on the first actuator rod 65 between the grooves therein to lock the bracket 87 against rotation. There are 20 splines on the rod 65 and in the ring 88 and since three equally spaced screws are utilized (FIG. 14), the bracket 87 may be clamped in 60 different desired rotative positions on the rod 65. The bracket 87 has a pair of spaced ears 98 and a pair of gripper fingers 99 are arranged between and pivoted to the ears 98 by pivots 100. The pivoted gripper fingers 99 are connected by links 101 to a bracket 102 carried by the projection 74 on the second actuator rod '71, the bracket 102 being secured in place on the projection 74 by a snap ring 103.

en both of the actuator rods 65 and 71 are in their retracted positions and in their advanced positions with the shoulder 73 on the second actuator rod 71 engaging the first actuator rod 65, the gripper fingers 99 are opened as illustrated. However, when the first and second actuator rods 65 and 71 are advanced to their advanced position and the second actuator rod 71 is advanced beyond the advanced position to the projected position, the bracket 102 is moved outwardly to cause the links 101 to close the gripper fingers 99. When the second actuator rod 71 is retracted from the projected position to the advanced position where the shoulder 73 on the second actuator rod 71 engages the end of the first actuator rod 65, the bracket 102 on the second actuator rod 71 is retracted to cause the links 101 to open the gripper fingers 99. To aid in adjusting the gripper finger mechanisms in their work gripping positions, the opposite ends of the second actuator rods 71 are threaded and provided with nuts 71A. In setting up the transfer assembly, the longitudinally reciprocatable rod 24 is moved to the left to advance the gripper finger mechanisms 21 and close the gripper fingers thereof and one of the nuts 85 on the rod 24 adjacent each gripper mechanism 20 is backed off to allow desired setting of the fingers in their closed positions. The nuts 71A are then drawn up against the end of the first actuator rod 65 and locked in place to fix the set positions of the closed fingers for the particular work pieces gripped thereby. Then the nuts 85 on the rod 24 are drawn up against the racks 83. In this way the closed positions of the gripper fingers may be individually accurately set. Also, by utilizing the nuts 71A the set position is always assured even though it may be necessary to back off the nuts 85 to release a faulty work piece from between the fingers should this occur and be required.

Referring to FIGS. 4 and 5, the feed bars 19 carry a plurality of lubricating fittings 106 for supplying lubricant through connections 107 to the moving parts of the gripper mechanisms 20, suitable lubricant being supplied to the lubricating fittings 106 from a lubricant supply line 108. The feed bars 19 also carry terminal boxes 110 having leads 111 extending to the gripper fingers for providing an electrical signal to indicate that the work pieces are properly gripped by the gripper fingers of the gripper assembly. In the even that the work pieces are not properly gripped the signal operates to shut down the press.

While for purposes of illustration one form of this invention has been disclosed, other forms thereof may become apparent to those skilled in the art reference to this disclosure.

I claim: 1

1. In a transfer assembly for a press for gripping and transferring work pieces from station to station along the press and including at least one longitudinally movable feed bar, at least one gripper mechanism carried by said at least one feed bar for longitudinally moving gripper finger mechanisms having gripper fingers to grip and release work pieces for transferring the work pieces as said at least one feed bar is longitudinally moved and at least one lifter mechanism for raising and lowering said at least one longitudinally movable feed bar, the improvement wherein each said lifter mechanism includes a lifter housing, a plunger vertically slidably mounted in said housing and extending upwardly therefrom, a bracket carried by the upper end of said plunger and having supporting and guiding rollers thereon, guide tracks on said at least one longitudinally movable feed bar engageable with said supporting and guiding rollers for supporting and guiding said at least one feed bar for longitudinal movement, and means for raising and lowering said plunger for raising and lowering said at least one longitudinally movable feed bar.

2. The combination of claim 1 wherein said means for raising and lowering said plunger includes a driven gear in said housing and rotatable in opposite directions, and a rack on said plunger engageable with said driven gear for raising and lowering the plunger as the gear is rotated.

3. The combination of claim 2 including a driving gear in the housing associated with said driven gear for driving the same, and at least one longitudinally reciprocatable rod extending lengthwise of said at least one feed bar into the housing, and a rack on said at least one longitudinally reciprocatable rod engageable with said driving gear for driving the same to raise and lower said plunger and hence said at least one longitudinally movable feed bar.

4. The combination of claim 1 including means supplying air under pressure below said plunger to in supporting the load carried by said plunger.

5. The combination of claim 2 including means for supplying air under pressure below said plunger to aid in supporting the load carried by said plunger.

6. The combination of claim 3 including means supplying air under pressure below said plunger to in supporting the load carried by said plunger.

7. The combination of claim 1 including means for longitudinally moving said at least one feed bar in one direction when said at least one feed bar is in a raised position and for longitudinally moving said at least one feed bar in the opposite direction when said at least one feed bar is in a lowered position.

8. The combination of claim 3 including means for longitudinally moving said at least one feed bar in one direction when said at least one feed bar is in a raised position and for longitudinally moving said at least one feed bar in the opposite direction when said at least one feed bar is in a lowered position.

9. The combination of claim 1 wherein the guide tracks on said at least one longitudinally movable feed bar extend longitudinally therealong and project laterally therefrom, and said supporting and guiding rollers on said bracket are arranged below, above and laterally of said guide tracks.

10. The combination of claim 2 wherein the guide tracks on said at least one longitudinally movable feed bar extend longitudinally therealong and project laterally therefrom, and said supporting and guiding rollers on said bracket are arranged below, above and laterally of said guide tracks.

11. The combination of claim 3 wherein the guide tracks on said at least on longitudinally movable feed bar for aid for aid extend longitudinally therealong and project laterally therefrom, and said supporting and guiding rollers on said bracket are arranged below, above and laterally of said guide tracks.

12. The combination of claim 10 including means for longitudinally moving said at least one feed bar in one direction when said lat least one feed bar is in a raised position and for longitudinally moving said at least one feed bar in the opposite direction when said at least one feed bar is in a lowered position.

13. The combination of claim 11 including means for longitudinally moving said at least one feed bar in one direction when said at least one feed bar is in a raised position and for longitudinally moving said at least one feed bar in the opposite direction when said at least one feed bar is in a lowered position.

14. The combination of claim 1 wherein said at least one gripper mechanism carried by said at least one feed bar includes means for laterally moving said gripper finger mechanisms between advanced and retracted positions and for closing and opening the fingers thereof when in advanced position.

15. The combination of claim 7 wherein said at least one gripper mechanism carried by said at least one feed bar includes means for laterally moving said gripper finger mechanisms between advanced and retracted positions and for closing and opening the fingers thereof when in advanced position and means for operating said at least one gripper mechanism to advance said gripper finger mechanisms and close the fingers thereof before said at least one feed bar is raised and before it is longitudinally moved in one direction and for operating said at least one gripper finger mechanism to open the fingers thereof and retract the same after said at least one feed bar is lowered and before it is longitudinally moved in the opposite direction.

References Cited UNITED STATES PATENTS 3,001,651 9/1961 Fekete 2l41 3,165,192 1/1965 Wallis 2141 GERALD M. FORLENZA, Primary Examiner 13.5. C1. X.R. 198-218

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