GB1584576A

GB1584576A - Article transfer mechanism

Info

Publication number: GB1584576A
Application number: GB4925077A
Authority: GB
Original assignee: Gulf and Western Manufacturing Co
Current assignee: Gulf and Western Manufacturing Co
Priority date: 1976-12-23
Filing date: 1977-11-25
Publication date: 1981-02-11
Also published as: JPS53104481A; FR2375117B1; IT1090924B; CA1064849A; DE2756096A1; DE2756096C2; FR2375117A1; AU2981777A; AU510543B2; DE7738370U1

Description

(54) ARTICLE TRANSFER MECHANISM (71) We, GULF & WESTERN MANUFACTURING COMPANY, a corporation organised under the laws of the State of Delaware, United States of America, of 23100 Providence Drive, Southfield, Michigan 48075, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in the following statement: This invention relates to the art of material handling and, more particularly, to a reciprocating article transfer mechanism for advancing articles step by step along a linear feed path.

The present invention finds particular.

utility in connection with the step by step advancement of a workpiece relative to a plurality of work stations in a metalworking press. Accordingly, the invention will be described with regard to such use; however, it will be appreciated that the invention has utility in connection with transferring articles other than press workpieces and in conjunction with apparatus other than presses.

Transfer feed mechanism have been provided heretofore for advancing workpieces step by step through a metalworking press such that a workpiece is picked up at one station, advanced to the next station and then released for the performance of work thereon by the press. Among such transfer mechanisms are those including a pair of longitudinally and laterally reciprocable feed bars having opposed pairs of cooperable feed fingers therebetween. The feed bars are adapted to be displaced laterally away from one another to release the fingers from engagement with an article, displaced longitudinally in one direction to position another set of fingers in alignment with the article, displaced laterally toward one another for the article to be received between the new pair of fingers, and then advanced longitudinally in the opposite direction to move the article to the next work station. Such movement is of course coordinated with the stroke of the press slide such that the engagement transfer and release functions of the feed mechanism take place during the non-working portion of the total stroke of the press.

A variety of arrangements have been provided heretofore for imparting the longitudinal and lateral reciprocating motions to the feed bars and thus the feed fingers associated therewith. Such previous efforts have included cam and linkage assemblies including rotating cams and long linkage trains involving a number of pivotally interrelated component parts. Other arrangements have included oscillating levers and linkage trains, again involving a considerable number of pivotally interconnected component parts. In view of the longitudinal and lateral reciprocating motions imparted to the feed bars it is necessary to have separate drive mechanisms therefore which generally are driven from a common drive source such as the crankshaft of the press so as to coordinate the operation. Even though the mechanisms are driven by the press, a principal disadvantage of the mechanisms heretofore provided has been the inability to time the separate longitudinal and lateral displacements with sufficient precision for high speed press operation. In this respect, links, levers, bell cranks and the like, introduce errors through long chains of action which effect the ability to achieve and maintain desired timing relationships between the longitudinal and lateral displacements. Further, operation of a feed transfer mechanism is continuous and accordingly requires a continuous and repeated change of direction with respect to the feed bars. In connection with this requirement, the drive arrangements heretofore provided consume a considerable amount of energy as a result of heavy links, levers, bell cranks and the like, whereby high frictional losses are encountered which hinder high speed operation. Thus, the inability to obtain close coordinated action of the longitudinal and lateral drives for the feed bars heretofore has impeded the use of such feed mechanisms in high speed presses.

-The foregoing and other difficulties and disadvantages encountered in connection with previous transfer feed mechanism are overcome or minimized in accordance with a presently preferred embodiment of the present invention described in detail below, which achieves lateral displacement of the feeds bars and minimizes energy loss and 'enables improved timing capabilities and thus higher speed press operation than heretofore possible.

In accordance with the present invention, there is provided an article transfer mechan ism comprising a pair of elongate feed members each having a plurality of feed fingers located between opposite ends of the members, the fingers of one feed member being opposed to respective fingers of the other feed member; two support means located one at each end of the pair of feed members, each support means including a pair of support members, one supporting each feed member, the support members being supported for linear reciprocation laterally toward and away from one another, each support member receiving and supporting the corresponding end of one of said feed members for longitudinal sliding movement relative thereto; means for reciprocating said feed members longitu dinally; a pair of pivotal levers, each lever of said pair having one end pivotally intercon nected with a support for the support members and the other end slidably engag ing a corresponding one of the support members; a rotatable cam between the levers; biasing means biasing the levers toward engagement with the cam; and means for rotating the cam so that the cam levers and biasing means reciprocate the support members and feed bars laterally toward and away from one another.

In the embodiment described below a continuously rotating cam is associated with the feed bars for achieving relative lateral displacement therebetween. This con tinuous rotating drive arrangement enables optimizing timing of such lateral reciproca tion and thus coordination thereof with longitudinal reciprocation of the feed bars.

Moreover, by maximizing rotary motion to achieve lateral displacement of the feed bars, energy losses heretofore encountered through long linkage trains is minimized.

Further, by use of a cam in accordance with the preferred embodiment of the invention, two in and out motions of the feed bars are realized for each revolution of the cam, thus further reducing energy losses heretofore encountered and reducing inertia loads on the cam, thus enabling higher speed press operation. Still further, reciprocating ,movement of the feed bars is preferably achieved through use of rotary-to-oscillatory drive mechanism, whereby the input to the separate drive mechanisms for achieving lateral and longitudinal reciprocation are both rotary. This enables optimizing the timing between the lateral and longitudinal reciprocating movement of the feed bars.

A transfer feed mechanism in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of the transfer feed mechanism; Figure 2 is a side elevation view of the mechanism in the direction of line 2-2 in Figure 1; Figure 3 is an end elevation view of the mechanism in the direction of line 3-3 in Figure 2; Figure 4 is a plan view, partially in section, of a drive arrangement by which feed bars are laterally reciprocated as seen along line 4-4 in Figure 3; Figure 4A is a view similar to Figure 4 but showing the component parts in different positions; Figure 5 is a sectional elevation view taken along line 5-5 in Figure 4, and, Figure 6 is a sectional elevation view taken along line 6-6 in Figure 4.

Referring now in greater detail to the drawings, Figures 1-3 illustrate a transfer feed mechanism for use with a press in which a workpiece is to be transferred step by step to a plurality of successive work stations between opposite sides of the press.

As is well known in the art, workpieces are conveyed to the input end of the transfer mechanism and are moved step by step across the press bed or a bolster plate thereon to the exit end of the transfer mechanism at which point the workpieces are picked up by a suitable discharge conveying mechanism. Accordingly, it will be appreciated with regard to Figures 1-3 that the transfer feed mechanism designated generally by the numeral 10 is mounted on the press frame to span the press bed such that workpieces W are transferred across the press bed from input end 12 to discharge end 14 of the transfer mechanism. Basically, the transfer feed mechanism includes a pair of parallel feed bars 16 carrying a plurality of opposed pairs of feed fingers 18 along the lengths thereof. Typically, bars 16 are reciprocated longitudinally and laterally in' a pattern which provides for fingers 18 to move laterally apart to release a workpiece therebetween, to move longitudinally in the direction of input end 12 of the mechanism, to move laterally inwardly to grip a new workpiece therebetween, and then to move longitudinally in the direction of output end 14 of the mechanism to transfer the workpiece to the next work station.

In the embodiment illustrated, feed bars 16 are longitudinally reciprocated by means of a drive unit 20 at the input end of the feed mechanism and are laterally reciprocated by means of a drive unit 22 at the input end of the mechanism and a similar drive unit 24 at the discharge end of the drive unit and which is driven in synchronism with drive unit 22 through a cross shaft 23 therebetween. As will be described in greater detail hereinafter, the opposite ends of feed bars 16 are supported for longitudinal and lateral reciprocation relative to the press bed by components of drive units 22 and 24.

Drive unit 20 is a mechanism adapted to translate rotary motion into oscillating mo tion and, in the preferred embodiment, is a well known and commercially available Fer guson (Registered Trade Mark) Cam Box.

As is well known in the art, such a unit has a rotatable input shaft 26 and an output shaft 28 which oscillates in response to rotation of shaft 26. One end of input shaft 26 is connected to the press crankshaft, not shown, through a timing belt 30 so that oscillation of output shaft 28 is timed with respect to the press drive. Input shaft 26 extends through the cam box and the other end of the shaft is connected with an input shaft 32 of drive unit 22 through a timing belt 34. The timing belt provides for the operation of drive units 22 and 24 to be synchronized with the oscillating move ments of output shaft 28 of drive unit 20. It will be appreciated of course that drive unit 20 is suitably mounted on the press frame such as by a bracket assembly 36 and that drive units 22 and 24 are likewise suitably mounted on the press frame such as by corresponding bracket assemblies 38. Out put shaft 28 of drive unit 20 is coupled to a member 40 provided with a pair of laterally spaced apart arms 42, and feed bars 16 are reciprocated together longitudinally by means of corresponding wobble links 44 coupled to arms 42 by universal couplings 46 and to feed bars 16 by universal couplings 48.

Feed bars 16 are laterally reciprocated relative to one another and to the press bed by means of drive units 22 and 24. The latter drive units are substantially identical in structure and operation and the differences therebetween will be apparent and will be pointed out hereinafter in conjunction with the description of drive unit 22 ilustrated in Figures 4-6 of the drawing. With regard to the latter Figures, drive unit 22 includes a housing 50 provided with a cover 52. The end of housing 50 facing the press is open to receive the corresponding ends of feed bars 16, and the latter ends of the feed bars are longitudinally slidably received in corresponding feed bar support members 54.

More particularly, each member 54 is provided with a, recess 55 slidably receiving the corresponding feed bar and which recess is covered by a plate 56 to retain the feed bar against upward displacement relative to the support members. Each support member 54 is provided with a pair of parallel laterally extending openings 58 receiving corresponding laterally extending guide rods 60 having opposite ends fastened in place with respect to housing 50 such as by correspond- ing brackets 62. Preferably, bearing sleeves 64 are interposed between openings 58 and rods 60 to enhance lateral sliding of support members 54 along the guide rods.

Housing 50 is further provided with a circular post 66 which is fixed relative to the housing and which supports a driven gear 68 for rotation about the vertical axis of post 66. Gear 68 has a hub portion 70 providing a shoulder 72, and an apertured cam member 74 receives hub 70 and rests on shoulder 72.

Cam 74 is suitably attached to gear 68, such as by a shrink fit therebetween, so that the cam is rotatable with the gear. Cam 74 is a double cam having a major axis 76 and a minor axis 78 and a peripheral cam surface 80 which is identical in each of the four quadrants defined by the major and minor axes.

A pair of follower levers 82 are disposed between cam 74 and a corresponding one of the feed bar support members 54. Each lever 82 has one end 84 pivotally interconnected with housing 50 and its other end 86 interconnected with the corresponding support member 54 for sliding engagement.

therewith. Further, each lever is provided intermediate its opposite ends with depending follower rollers 88, which rollers engage diametrically opposite sides of cam surface 80 of cam 74. Follower rollers 88 are biased toward cam surface 80 by means of a pair of tension springs 90 each having their opposite ends connected to one of the feed bar support members 54 such as by means of pins 92.

It will be appreciated from the description thus far of drive unit 22 that rotation of gear 68 rotates cam 74 about the axis of post 66 and that such rotation of the cam imparts reciprocating movement to feed bar support members 54 laterally toward and away from one another. It will be appreciated too that when the cam component is in the position illustrated in Figure 4 support members 54 are in the positions of maximum lateral spacing therebetween, and when the cam component is in the position illustrated in Figure 4A support members 54 are in the positions of minimum lateral spacing therebetween. It will be further appreciated that double cam 74 provides for lateral outward and inward movement of members 54 twice for each revolution of the cam, that the cam drives support members 54 outwardly against the bias of springs 90, and that the springs return the support members inwardly as the cam rotates from the position of Figure 4 to that of Figure 4A.

Gear 68 is adapted to be rotated constantly through a gear train driven in response to rotation of input shaft 32 and including, in sequence from input shaft 32, gears 94, 96, 98 and 100. As mentioned hereinabove, drive units 22 and 24 are adapted to be driven in synchronism through cross shaft 23. Input shaft 32 of drive unit 22 extends through housing 50, and it will be seen from Figure 4 that input shaft 32 is coupled with cross shaft 23 by means of a suitable coupling 102.

Drive unit 22 further includes an auxiliary cam 104 having cam lobes 106 normally positioned as shown in Figure 4. Cam 104 is mounted on post 66 for rotation relative thereto and relative to cam 74, and lobes 106 are coplanar with levers 82. When feed bar support members 54 are in the laterally inward positions shown in Figure 4A, cam 104 is adapted to be pivoted to displace lobes 106 into engagement with the sides of levers 82. This displaces the levers 82 and thus support members 54 laterally outwardly independent of cam 74. This provides for an emergency release of the feed fingers of feed bars 16 relative to workpieces therebetween in the event a malfunction or other emergency condition.

In the embodiment shown, cam 104 is adapted to be pivoted clockwise as viewed in Figure 4 to achieve such spreading of the feed bars by means of a pneumatic piston and cylinder unit 108. More particularly, unit 108 includes a cylinder 110 mounted on housing 50 and supporting a reciprocable piston 112 having a piston rod 114 extending through an opening in the housing. The inner end of piston rod 114 is connected with cam 104 by means of a connecting link 116 having its opposite ends pivotally interconnected one with the piston rod and the other with cam 104. Return movement of cam 104 to the position shown in Figure 4 is achieved through a tension spring 118 having its opposite ends connected to cam 104 and housing 50. It will be appreciated of course that cylinder 110 is connected to a suitable source of air under pressure, not shown.

As mentioned hereinabove, drive units 22 and 24 are substantially identical in structure. In fact, the only difference is a reversal of the positions of the component parts to provide for unit 24 to be driven from the same side as the input to unit 22, and to position auxiliary cam actuator 108 for unit 24 on the same side as that of unit 22. It will appreciated that cross shaft 23 is connected through a coupling 120 with an input shaft of drive unit 24 equivalent to input shaft 32 of unit 22. Accordingly, rotation of input shaft 32 of unit 22 imparts identical rotation to the input shaft of unit 24, whereby the two units are driven in synchronism to achieve simultaneous lateral reciprocation of feed bars 16 outwardly and inwardly relative to one another. It will be appreciated too that piston cylinder units 108 of drive units 22 and 24 can be connected to a common source of air under pressure and can be operated together.

It will be understood from the foregoing description that the transfer feed mechanism is operated through the press and in timed coordination therewith through timing belt 30. Further, it will be appreciated that the operation of drive unit 20 is coordinated with the operation of drive units 22 and 24 through timing belt 34 between units 20 and 22. Thus, rotation of timing belt 30 through operation of the press imparts oscillating movement to output shaft 28 to reciprocate feed bars 16 longitudinally relative to the press and rotation of input shaft 32 of drive unit 22 through timing belt 34 causes reciprocation of the feed bars laterally relative to one another in timed coordination with such longitudinal reciprocation. Therefore, during a cycle of operation feed bars 16 are displaced longitudinally in one direction while in their laterally inward positions, are displaced laterally outwardly relative to one another, are displaced longitudinally in the opposite direction, and are displaced laterally inwardly toward one another to complete the cycle.

During each cycle of movement double cam 74 rotates one-half revolution. It will be appreciated, therefore, that the press will perform two working operations for each full revolution of cam 74, thus minimizing the inertia of working parts of drive units 22 and 24 relative to that which would be encountered with mechanisms requiring a complete cycle of operation of these parts with each cycle of press operation. Additionally, it will be appreciated that a continuous rotational drive for units 22 and 24 with minimum use of linkage arrangements between the various component parts thereof minimizes energy losses and inaccuracies in timing with regard to coordinating movements of the feed bars in the longitudinal and lateral directions.

While considerable emphasis has been placed herein on the specific structure and structural interrelationships between the component parts of drive units 22 and 24, it will be appreciated that many modifications can be made in the structures shown and described without departing from the principles of the present invention. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the present invention and not as a limitation.

The use of the cam drive arrangement enables reducing the number of moving parts required to achieve the desired lateral movements of the feed bars and thus decreases frictional losses and inertial forces on the component parts to improve accuracy with respect to coordinating drives for the lateral and longitudinal movements and to enable higher speed operation than heretofore possible.

WHAT WE CLAIM IS: 1. An article transfer mechanism comprising a pair of elongate feed members each having a plurality of fingers located between opposite ends of the members, the fingers of one feed member being opposed to respective fingers of the other feed member; two support means located one at each end of the pair of feed members, each support means including a pair of support members, one supporting each feed member, the support members being supported for linear reciprocation laterally toward and away from one another, each support member receiving and supporting the corresponding end of one of said feed members for longitudinal sliding movement relative thereto; means for reciprocating said feed members longitudinally; a pair of pivotal levers, each lever of said pair having one end pivotally interconnected with a support for the support members and the other end slidably engaging a corresponding one of the support members; a rotatable cam between the levers; biasing means biasing the levers toward engagement with the cam; and means for rotating the cam so that the cam levers and biasing means reciprocate the support members and feed bars laterally toward and away from one another.

2. A transfer mechanism according to claim 1, wherein the biasing means comprises a spring between each pair of support members.

3. A transfer mechanism according to claim 1 or 2, wherein the means for rotating each cam includes common drive means for rotating the cams in synchronism.

4. A transfer mechanism according to any of claims 1 to 3, wherein each support means includes a pivotal cam between the levers, the pivotal cam being operable independently of the corresponding rotatable cam to engage said levers and displace the feed members and support members laterally away from one another, and means to pivot the pivotal cam.

5. A transfer mechanism according to claim 4, wherein the rotatable and pivotal cams at each of said ends are coaxial with one another.

6. A transfer mechanism according to claim 4 or 5, wherein said means for pivoting the pivotal cam includes corresponding pneumatic motor means and spring means, said motor means pivoting the pivotal cam in one direction and said spring means biasing the pivotal cam in the opposite direction.

7. A transfer mechanism according to any of claims 1 to 6, wherein each said rotatable cam is rotatable about an axis perpendicular to the plane of lateral movement of the feed members.

8. A transfer mechanism according to claim 7, wherein the levers of each said pairs of levers are pivotal about axes parallel to and spaced from the rotatable cam axis.

9. A transfer mechanism according to any of claims 1 to 8, wherein each rotatable cam is arranged to reciprocate the support members twice during each revolution.

10. An article transfer mechanism constructed and arranged substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. will be appreciated that many modifications can be made in the structures shown and described without departing from the principles of the present invention. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the present invention and not as a limitation. The use of the cam drive arrangement enables reducing the number of moving parts required to achieve the desired lateral movements of the feed bars and thus decreases frictional losses and inertial forces on the component parts to improve accuracy with respect to coordinating drives for the lateral and longitudinal movements and to enable higher speed operation than heretofore possible. WHAT WE CLAIM IS:

1. An article transfer mechanism comprising a pair of elongate feed members each having a plurality of fingers located between opposite ends of the members, the fingers of one feed member being opposed to respective fingers of the other feed member; two support means located one at each end of the pair of feed members, each support means including a pair of support members, one supporting each feed member, the support members being supported for linear reciprocation laterally toward and away from one another, each support member receiving and supporting the corresponding end of one of said feed members for longitudinal sliding movement relative thereto; means for reciprocating said feed members longitudinally; a pair of pivotal levers, each lever of said pair having one end pivotally interconnected with a support for the support members and the other end slidably engaging a corresponding one of the support members; a rotatable cam between the levers; biasing means biasing the levers toward engagement with the cam; and means for rotating the cam so that the cam levers and biasing means reciprocate the support members and feed bars laterally toward and away from one another.