US3653293A

US3653293A - Press unloader

Info

Publication number: US3653293A
Application number: US62004A
Authority: US
Inventors: Bernard J Wallis
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-08-07
Filing date: 1970-08-07
Publication date: 1972-04-04
Anticipated expiration: 1989-04-04

Abstract

A press unloader having a reciprocating tray for receiving workpieces ejected from an upper die in a press. The tray is shifted to the work-receiving position at a rate controlled by the upward rate of the press ram and is rapidly retracted at a rate independent of the rate of the press ram so that the next workpiece may be conveniently loaded into the press.

Description

United States Patent Wallis [is] I 3,653,293

[451 Apr. 4, 1972 [54] PRESS UNLOADER I [72] Inventor: Bernard J. Wallis, 25200 Trowbridge Avenue, Dearborn, Mich. 48124 [22] Filed: Aug. 7, 1970 21 App1.No.: 62,004

[51] Int. Cl ..B26d 7/06 [58] Field oiSearch .83/81, 82, 157; 72/361;

[56] References Cited I UNITED STATES PATENTS 2,377,262 5/1945 OLeary ..83/81 3,148,571 9/1964 Wallis ..83/82 3,349,602 10/1967 Nelson ..83/157X Primary Examiner-Andrew R. J uhasz Assistant Examiner-David R. Melton Attorney-Bames, Kisselle, Raisch & Choate [57] ABSTRACT A press unloader having a reciprocating tray for receiving workpieces ejected from an upper die in a press. The tray is shifted to the work-receiving position at a rate controlled by the upward rate of the press ram and is rapidly retracted at a rate independent of the rate of the press ram so that the next workpiece may be conveniently loaded into the press.

12 Claims, 6 Drawing Figures PATENTEDAPR 4 I972 sum 1 BF 3 Adjustable Deloq Valve FIG.@

ATTORNEYS PATENTEDAPR 4 I972 3, 653 293 SHEET 2 BF 3 1;; \/l:.\"l' JR. BERNARD J. WALLIS ATTORNEYS PATENTEDAPR 4 1972 SHEET 3 OF 3 INVENTOR.

BERNARD .J. WALLIS ATTORNEYS PRESS UNLOADER The present invention relates to material handling equipment and more particularly to a press unloader for mechani' cally unloading stampings or the like from between die elements in a press or similar machine without interrupting the operation of the machine.

The present invention is of particular utility in the unloading of a punch press in which the formed article is elevated with the upper die element as the die opens and is then ejected downwardly from the upper die element by knock-out pins which operate at the terminal portion of the upstroke of the press. One commonly used form of press unloader includes a tray arranged to reciprocate to a work-receiving position disposed between the separated upper and lower dies in the press so as to receive workpieces ejected from the upper die when the ram reaches the upper end of its stroke. Such an arrangement is illustrated in my prior U.S. Pat. No. 3,148,571, issued Sept. 15, 1964. With such an arrangement the reciprocation of the tray is controlled by the vertical movement of the ram. When the ram moves upwardly the tray is projected to the work-receiving position, and when the ram moves downwardly the tray is retracted to an out-of-the-way position. While such an arrangement is satisfactory in many applications, it presents a problem when the press is loaded manually. This problem arises from the fact that with an arrangement such as shown in my prior patent the work-receiving tray is not completely retracted until the press ram approaches the lower end of its stroke. Thus, it is difficult to load workpieces into the press while the tray is being retracted.

The object of the present invention is to provide a press unloader which enables workpieces to be conveniently and rapidly loaded into the press without interference from the press unloader.

More specifically, it is an object of the present invention to provide a press unloader of the reciprocating tray type wherein the tray is retracted rapidly from the work-receiving position while the ram is at the upper end of its stroke so that after a workpiece is ejected from the upper die the next workpiece can be loaded into the press without interference from the work-receiving tray. In the drawings:

FIG. 1 is a fragmentary elevational view of a press and press unloader of the present invention with the parts illustrated in the positions assumed when the press ram is at the upper end of its stroke.

FIG. 2 is a view similar to FIG. 1 and showing the position of the various parts when the press ram is at the lower end of its stroke.

FIG. 3 is a sectional view taken along line 33 in FIG. 2

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3.

FIG. 5 is a sectional view taken a long line 5-5 in FIG. 4.

FIG. 6 is a schematic diagram of the fluid control circuit.

Referring to the drawings, a punch press is generally indicated at 10. The press includes a base 12 and a ram 14. Ram 14 is guided for vertical reciprocating movement by means of guides 16. In use an upper die 18 is mounted on ram 14 and a lower die 20 is mounted on the platen 22 of the press.

The press unloader of this invention is generally designated 24 and is mounted at one side of base 12 by a bracket 26. Press unloader 24 generally comprises a drive assembly 28 and a tray assembly 30. Each of these assemblies is mounted on a base plate 32 in spaced-apart relation (FIG. 3). Drive assembly 28 includes a vertically extending gear rack 34 coupled at its upper end to an extension 36. Extension 36 is provided with a bumper element 38 at its upper end adapted to be engaged by a laterally extending bracket 40 mounted on and movable with ram 14. Rack 34 meshes with a gear 42 on a stub shaft 44 in drive assembly 28 (FIG. 4). Stub shaft 44 also carries a larger gear 46 which meshes with another gear 48 at one end of a coupling shaft 50 extending between drive assembly 28 and tray assembly 30. A gear 52 at the other end of shaft 50 meshes with a gear rack 54 secured to the lower side of a workpiece-receiving tray 56 (FIG. 5 Tray 56 is supported on a bracket 58 by means of four rollers 60 (two at each side of the tray) which engage with guideways 62 fonned along each side of gear rack 54. Bracket 58 is pivotally supported at the axis of shaft 50 on a base 64. Suitable studs and nuts 66 on bracket 58 cooperate with arcuate slots 68 on base 64 for adjusting tray 56 to the inclination desired.

The apparatus thus far described is in general the same as that disclosed in my prior U.S. Pat. No. 3,148,571.

With the arrangement thus described it will be appreciated that in response to vertical reciprocation of rack 34 tray 56 is reciprocated between the work-receiving position shown in FIG. 1 and the retracted position shown in FIG. 2. The upward travel of rack 34 causes tray 56 to move from the retracted position to the work-receiving position; the downward travel of the rack causes the tray to move from the work-receiving position to the retracted position. In the work-receiving position the upper end of tray 56 is located to receive workpieces 70 ejected from upper die 18. In the retracted position the upper end of tray 56 is disposed out of the path of travel of die 18 so as not to interfere therewith.

As shown in FIGS. 1 and 2 the lower end of rack 34 is coupled to the upper external end of a cylinder rod 72. The cylinder 74 associated with rod 72 is mounted on support bracket 26 by a depending bracket structure 76. The lower internal end of cylinder rod 72 is attached to a piston 78 which is adapted to reciprocate within cylinder 74. Cylinder 74 and rod 72 are vertically aligned with rack 34. Cylinder 74 has an upper port 80 and a lower port 82 through which pressure fluid is introduced to cause reciprocation of piston 78. The introduction of pressure fluid into the cylinder through port 80 causes piston 78 to travel downwardly while the introduction of pressure fluid into the cylinder through port 82 causes the piston to move upwardly. Thus it will be appreciated that the introduction of pressure fluid into cylinder 74 through port 82 causes tray 56 to be shifted toward the work-receiving position shown in FIG. 1. Similarly, the introduction of pressure fluid into cylinder 74 through port 80 causes tray 56 to be shifted toward the retracted position shown in FIG. 2.

FIG. 6 schematically shows the means for introducing pressure fluid into cylinder 74. A source of pressure fluid 84 is conducted to a two-position directional valve 86. With valve 86 in the position shown, pressure fluid is introduced into cylinder 74 through port 80. With valve 86 in the other position, pressure fluid is introduced into the cylinder through port 82.

Valve 86 is pilot operated by cam actuated

valves

88, 90. Valves 88, are identical two-position valves, to which pressure fluid is conducted directly from source 84. With valve 90 in the actuated position shown in FIG. 6, pressure fluid is conducted through it to an adjustable delay valve 92, which delays the flow of pressure fluid for a preselected interval, and then to one end of valve 86. This causes valve 86 to assume the position shown in FIG. 6. When valve 88 is actuated, pressure fluid is conducted through it directly to the opposite end of valve 86. This causes valve 86 to assume the other position.

Valve 88 is actuated when ram 14 is adjacent the lower end of its stroke thereby shifting tray 56 away from the retracted position toward the work-receiving position. Since the upward travel of rack 34 is limited by the contact of bumper 38 with ram bracket 40 the upward rate of the rack equals the upward rate of the ram. Thus, tray 56 is shifted to the work-receiving position at a rate proportional to the rate of the upward travel of the ram.

Valve 90 is actuated when ram 14 is adjacent the upper end of its stroke thereby shifting tray 56 away from the workreceiving position toward the retracted position. With rack 34 free to move downwardly, tray 56 is retracted at a relatively rapid rate independent of the rate of travel of the ram.

The significance of the present invention can be more fully appreciated by the following description of an operating cycle.

With ram 14 traveling downward tray 56 is located at the retracted position. As the ram reaches the lower end of its stroke, thereby bringing upper die 18 into engagement with lower die 20, valve 88 is actuated by ram bracket 40. This causes pressure fluid to be introduced into cylinder 74 through port 82, and rack 34 begins to travel upward. Since there will usually be a small gap between bumper element 38 and ram bracket 40 as the ram comes to the lower end of its stroke, an adjustable flow control valve 94 is placed in the connection between port 82 and valve 86. By limiting the flow of pressure fluid into cylinder 74, the impact of rack 34 on ram bracket 40 is thereby cushioned. However, the supply of pressure fluid into the cylinder is sufficient to maintain the contact of rack 34 against bracket 40 as the ram rises. Thus tray 56 shifts from the retracted to the work-receiving position at a rate proportional to the speed of the ram on its upstroke.

As ram 14 reaches the upper end of its stroke tray 56 is disposed beneath upper die 18 at the work-receiving position. At the same time valve 90 is actuated by ram bracket 40. Delay valve 92 is adjusted such that workpieces are ejected onto tray 56 before the signal from valve 90 is allowedto shift valve 86 to the position shown in FIG. 6. After valve 86 has been shifted by valve 90, pressure fluid is introduced into cylinder 74 through port 80 and tray 56 retracts rapidly while ram 14 remains at the upper end of its stroke after having completed its cycle. If desired, the rate of tray retraction may be controlled by a flow control valve 96 inserted between valve 86 and port 80..Once tray 56 is in the retracted position it will remain there until valve 88 is again actuated by ram 14.

Thus, because of the operative coupling between tray 56 and ram 14 during the press upstroke, the tray will always be shifted to its work-receiving position with maximum speed and positive accuracy. Because this operative connection is broken after the press ram reaches the upper end of its stroke,

the tray may be rapidly retracted independent of the press ram position. This leaves the space between the upper and lower dies free and clear for the loading of the next workpiece.

I claim:

1. In combination a press having a vertically reciprocating ram on which an upper die is adapted to be mounted for cooperation with a lower die mounted on the bed of the press, a press unloader for receiving workpieces ejected from the upper die when the dies are vertically separated, said unloader comprising a tray shiftable from a work-receiving position disposed between the vertically separated upper and lower dies to a retracted position out of the path of travel of the upper die, means operative with the upward movement of the press ram and movable at a rate determined bythe upward rate and movable at a rate determined by the upward rate of travel of the press ram for shifting said tray from said retracted position to said work-receiving position, means for retracting the tray at a rate of travel greater than said rate of tray travel during shifting to the work-receiving position, and means for actuating the tray retracting means when the ram reaches a predetermined position.

2. The combination set forth in claim 1 wherein said means for shifting the tray from the retracted position to the workreceiving position is adapted to move the tray at a rate proportional to the rate of travel of the ram on its upward stroke.

3. The combination set forth in claim 1 wherein said means for shifting the tray from the retracted position to the workreceiving position comprises a vertically reciprocating shaft.

4. The combination set forth in claim 3 including means for interengaging said shaft and the ram on the upstroke of the ram.

5. The combination set forth in claim 4 wherein said lastmentioned means includes a fluid cylinder having a piston operatively connected with said shaft.

6. The combination set forth in claim 5 wherein the piston is adapted to shift said shaft vertically in opposite directions in response to application of fluid pressure to opposite sides thereof.

7. The combination set forth in claim 6 wherein said means for shifting the tray to the work-receiving position comprises abutment means located between said ram and the upper end portion of said shaft and valve means for directing pressure fluid to one side of the piston for interengaging said abutment means on the upward stroke of the ram for causing said tray to shift from said retracted position to said work-receiving position at a rate controlled by the upward rate of travel of the ram.

8. The combination set forth in claim 7 wherein said means for retracting said tray includes said cylinder and said means for actuating the tray retracting means includes valve means which when actuated is adapted to apply pressure fluid to the opposite side of the piston for displacing said shaft downwardly at a rate in excess of the rate of travel of the ram on its downward stroke.

9. The combination set forth in claim 8 including an actuator for said last-mentioned valve means, said actuator being disposed so as to be tripped by the ram when the ram reaches a predetermined position.

10. The combination set forth in claim 1 wherein said predetermined position is adjacent the upper end of the ram stroke.

11. In combination a press having a vertically reciprocating ram on which an upper die element is adapted to be mounted for cooperation with a lower die mounted on the bed of the press, a press unloader for receiving workpieces ejected from the upper die when the dies are vertically separated, said unloader comprising a tray shiftable from a work-receiving position disposed between the vertically separated upper and lower dies to a retracted position out of the path of travel of the upper die, means operative with the upward movement of the press ram for shifting the tray from said retracted position to said work-receiving position at a rate of travel determined by the rate of travel of the ram, means biasing the tray toward said retracted position for retracting the tray at a rate of travel greater than the rate at which the tray is shifted to the workreceiving position, and means for rendering said biasing means effective as the ram approaches the upper end of its stroke.

12. The combination set forth in claim 11 including means for rendering said biasing means ineffective as the ram approaches the lower end of its stroke.

Claims

1. In combination a press having a vertically reciprocating ram on which an upper die is adapted to be mounted for cooperation with a lower die mounted on the bed of the press, a press unloader for receiving workpieces ejected from the upper die when the dies are vertically separated, said unloader comprising a tray shiftable from a work-receiving position disposed between the vertically separated upper and lower dies to a retracted position out of the path of travel of the upper die, means operative with the upward movement of the press ram and movable aT a rate determined by the upward rate and movable at a rate determined by the upward rate of travel of the press ram for shifting said tray from said retracted position to said workreceiving position, means for retracting the tray at a rate of travel greater than said rate of tray travel during shifting to the work-receiving position, and means for actuating the tray retracting means when the ram reaches a predetermined position.

2. The combination set forth in claim 1 wherein said means for shifting the tray from the retracted position to the work-receiving position is adapted to move the tray at a rate proportional to the rate of travel of the ram on its upward stroke.

3. The combination set forth in claim 1 wherein said means for shifting the tray from the retracted position to the work-receiving position comprises a vertically reciprocating shaft.

5. The combination set forth in claim 4 wherein said last-mentioned means includes a fluid cylinder having a piston operatively connected with said shaft.

11. In combination a press having a vertically reciprocating ram on which an upper die element is adapted to be mounted for cooperation with a lower die mounted on the bed of the press, a press unloader for receiving workpieces ejected from the upper die when the dies are vertically separated, said unloader comprising a tray shiftable from a work-receiving position disposed between the vertically separated upper and lower dies to a retracted position out of the path of travel of the upper die, means operative with the upward movement of the press ram for shifting the tray from said retracted position to said work-receiving position at a rate of travel determined by the rate of travel of the ram, means biasing the tray toward said retracted position for retracting the tray at a rate of travel greater than the rate at which the tray is shifted to the work-receiving position, and means for rendering said biasing means effective as the ram approaches the upper end of its stroke.