WO2001081023A2

WO2001081023A2 - Length compensation for punch tools

Info

Publication number: WO2001081023A2
Application number: PCT/US2001/040586
Authority: WO
Inventors: Gordon A. Straka
Original assignee: Wilson Tool International, Inc.
Priority date: 2000-04-26
Filing date: 2001-04-24
Publication date: 2001-11-01
Also published as: AU2001259800A1; AR028037A1; WO2001081023A3

Abstract

A length compensator for a punch tool enabling the punch to be utilized in an autoloading punch press utilizing a robotic tool transfer system to transfer punch tools into and out of the punch press. The compensator includes a first portion attachable to an end portion of the punch tool remote from the punch tip and adjustable lengthwise of the tool, and a second portion positioned to be further from the work contacting surface that the first portion when the latter is mounted to a punch tool. The second portion has an upper ram-engaging surface and is movably mounted to the first portion to enable movement of the second portion lengthwise of the punch tool between a first position in which the first and second portions are spaced from each other a predetermined distance and a second position enabling ram force to be delivered to the end portion of the punch tool. A spring is provided to urge the second portion into its first position, thereby increasing the length of the punch tool sufficiently to enable it to be gripped by the robotic transfer system.

Description

LENGTH COMPENSATION FOR PUNCH TOOLS

Background of the Invention

Turret-type punch presses employ an upper, generally cylindrical turret which holds a series of punch tools spaced circumferentially around its periphery, and a second, lower turret holding a series of dies circumferentially spaced about that turret's periphery, each turret being rotatable about a vertical axis to bring an appropriate punch and die pair into vertical alignment at a work station. By appropriately rotating the two turrets, an operator can bring a number of punches and dies sequentially into alignment at the work station to perform a series of sequential and different punching operations on a work piece.

Different punching projects, of course, require different punches and dies. In the past, the punches and dies needed for a project were manually loaded in the respective turrets. The loading operation has been automated, however, such that a robotic autoloading system may select certain punch and die combinations from an adjacent supply or reservoir of these tools and install them where desired in the upper and lower turrets. The punch tools are positioned upright in the tool reservoir, and the robotic system includes a gripping element that grips the top of each punch tool to lift it from the reservoir and move it into the desired position of the upper turret. A problem arises in use of an autoload system as described, however, in that some punch tools are shorter than others. The robotic system may be unable to grasp these punches because the tops of these punches are below the expected position in the tool reservoir. Short punch tools of this type may for example be punches that are not intended to pierce through a work piece and into a die, but rather are of a shorter length so as to perform a shorter stroke, as when an alphanumeric character is to be punched into the upper surface of a workpiece. It is difficult to adjust such punches so that their upper surfaces may be in the expected positions to be gripped by a robot arm, but yet maintain the length of the punch itself so that when it is contacted by the ram, the desired shorter punch stroke is performed.

It would be desirable to provide an adapter that would enable the upper end of a shorter punching tool to be at the appropriate height to be gripped by a robotic tool transfer system, while at the same time not changing the stroke imparted to the punch by a ram; that is, without changing the effective height of the ram-striking surface above the punch tip.

Summary of the Invention The present invention provides a length compensator for a punch tool having a punch with a punch tip to facilitate use of the punch tool in an autoloading punch press utilizing a robotic tool transfer system to transfer punch tools into and out of the punch press. The compensator includes a ram-striking surface positioned to be struck by a ram, and has a first portion attachable to an end portion of the punch tool remote from the punch tip and a second portion having an outer surface adapted to be gripped by a robotic transfer system. The second portion is carried by the first portion and extends beyond the ram-striking surface away from the punch tip to enable the second portion to be grasped by the robotic transfer system.

The length compensator in another embodiment comprises a first portion attachable to an end portion, commonly the upper end portion, of the punch tool remote from the punch tip, the first portion being adjustable lengthwise of the punch tool. A second portion is positioned to be further from the work contacting surface than the first portion when the latter is mounted to a punch tool. The second portion has an upper ram-engaging surface, and is movably attached to the first portion to enable the second portion to move lengthwise of the punch tool (that is, axially of the punch tool) between a first position in which the first and second portions are spaced from each other a predetermined distance, and a second position nearer the punch tip and that enables ram force to be delivered to the end portion of the punch tool. In the last-described embodiment, the first and second portions may have confronting, load-transferring sur aces such that when the second portion is moved under ram force into contact with the first portion, the load transferring surfaces serve to transfer ram force to the end portion of the punch tool. Preferably, however, the first portion includes a ram-striking surface that extends beyond the end of the end portion of the punch tool. In this preferred version, during a punching operation, the ram forces the second portion toward the punch tip sufficiently to expose the ram-striking surface and enable it to be struck directly by the ram. Spring means are provided to urge the second portion into its first position to increase the length of the punch tool sufficiently to enable it to be gripped by a robotic transfer system. In another embodiment, the invention provides a punch tool including a length compensator to lengthen the punch tool so that it can be grasped by a robotic tool transfer system of an autoload punch press. The punch tool includes a punch with a punch tip and an end portion remote from the punch tip to facilitate use of the punch tool in an autoloading punch press utilizing a robotic tool transfer system to transfer punch tools into and out of the punch press. The length compensator comprises a first portion attached to the end portion of the punch tool remote from the punch tip. A second portion is carried by the first portion and positioned further from the punch tip than the first portion. The length compensator includes a ram-striking surface facing away from the punch tip, and the second compensator portion extends away from the punch tip beyond the ram-striking surface to provide added length to said punch tool.

In yet another embodiment, the invention provides a punch tool including a length compensator comprising first and second portions. The first portion is attached to the end portion of the punch tool, and the second portion is mounted to the first portion and positioned further from the punch tip than the first portion. The second portion has an upper ram-engaging surface and is movably attached to the first portion to enable movement of the second portion lengthwise of the punch tool by ram force between a first position in which the first and second portions are spaced from each other a predetermined distance to increase the effective length of the punch tool to enable it to be grasped by the robotic transfer system, and a second position nearer the punch tip and enabling ram force to be transferred to said end portion of the punch tool in a punching operation. Spring means are provided for urging the second portion into said first position. Here, ram force can be transferred directly to a ram-striking surface of the first portion as the second portion moves to expose the ram-striking surface to the ram. Alternatively, but less desirably, the first and second portions have confronting, load-transferring surfaces such that when the second portion is moved under ram force into contact with the first portion, the load transferring surfaces serve to transfer ram force to the end portion of the punch tool. Description of the Drawings

Figure 1 is a top view of a length compensator of the invention;

Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1 ;

Figure 3 is a cross-sectional view taken along line 3-3 of Figure 1 ; Figure 4 is a side view of a punch tool containing the length compensator shown in Figures 1-3; and

Figure 5 is a broken away view, in partial cross-section showing another embodiment of a length compensator of the invention.

Detailed Description of the Preferred Embodiment

The present invention provides a length compensator for a punch tool that enables the length of the punch tool to be extended so that it can be grasped by a robotic tool transfer system, but that does not change the effective height between the work piece contacting surface and the ram-striking surface of the compensator. As used herein, "ram-striking surface" refers to a surface of the length compensator that is adapted, by configuration and location, to be struck by a punch press ram with the force of the ram being delivered by the ram-striking surface to the punch tip in a punching operation. "Ram-engaging surface" refers to a surface of a second portion of the length compensator in embodiments wherein the second portion is movable with respect to a first portion of the compensator, the first portion including a ram-striking surface. Here, as the ram descends during a punching operation, the ram first encounters the ram-engaging surface and depresses the second portion, preferably against spring pressure, until the ram encounters, directly or indirectly, the ram-striking surface of the first portion. With reference to Figures 1-3, a length compensator is shown generally as

10, and includes a bottom or first annular portion 12 and an upper, or second, annular portion 14. The first annular portion has a central bore 16 that is threaded to receive the threaded upper shaft 18 of a punch tool 20, as shown in Figure 4.

As typified in the drawing, the first portion 12 of the length compensator has a lower cylindrical portion 22 and an upper cylindrical portion 24 of lesser diameter and providing the lower portion with an annular shoulder 26. A set screw 28 extends radially inwardly of the cylindrical portion 22 to lock the first portion 12 to the threaded shank 18 of the punch. To avoid damage to the threads of the punch shank, one may provide a small pellet 30 of lead or other soft metal at the inner end of the set screw, the pellet conforming itself to the threads of the shaft 18. The cylindrical portion 24 of the first portion terminates upwardly in a ram-striking surface 60, which extends beyond the end of the threaded shaft 18 in position to be struck by a ram.

The second, or upper portion 14 has a central bore 32 within which the smaller diameter cylindrical portion 24 of the first portion is telescopically received, as shown best in Figures 2 and 3. Second portion 14 is provided with an annular shoulder 34 which faces the annular shoulder 26 of the first portion, the confronting surfaces of the annular shoulders preferably being normal to the length of the punch tool so that, in one embodiment, surface-to-surface contact between these surfaces may occur. The second portion 14 also is provided with an upper surface 36 that is generally perpendicular to central axis 38 of the length compensator 10 and which serves as a ram-engaging surface. Referring to Figures 1 and 2, spring means are provided to urge the first and second portions 12, 14 axially apart from one another, that is, apart from one another lengthwise of the punch tool. Any appropriate spring means will suffice, provided that the facing annular surfaces 34, 26 are permitted to approach each other sufficiently to expose the ram-striking surface 60, in one embodiment, or to transfer ram force to the punch tip through load transferring contact between the surfaces 34, 26, in another, less-preferred embodiment. Helical springs 40 are preferred, the springs being received in spring seats 42, 44 (Figure 2) formed in the respective annular surfaces 26, 34 and spaced circumferentially about the length compensator. Three circumferentially spaced helical springs are shown in Figure 1 , although any convenient number may be used. Other springs, such as wave springs and disc springs could be used as well. When placed under compression, these springs flattening out between the surfaces 26, 34 to enable force to be transmitted through them from one of these annular surfaces to the other.

Stops are provided to limit the distance that the second portion 14 can move axially away from the first portion 12 under the influence of the springs 40. Typified in Figures 1 and 2 are a plurality of pins 46 having lower ends threaded into threaded bores 48 formed in the larger cylindrical portion 22. The pins terminate upwardly in enlarged heads 50 which are slidably received in larger diameter bores 52 formed in the second portion 14. Bores 52 undergo a sharp reduction in diameter to provide upwardly facing shoulders 54 which engage the heads 50 to limit the distance that the first and second portions can be separated.

From Figure 2, it will be noted that as the second portion 14 slides downwardly into contact with the annular shoulder 26 of the first portion under the force of a descending ram (not shown), the pin heads 50 slide readily in the bores 52. When the second portion moves away from the first portion, under action of the springs 40, the pin heads 52 limit the travel of the second portion. It will also be understood that by adjusting the axial position of the pins 46 within the bore 48, the overall length of the punch tool can be adjusted, although this adjustment is more readily made by adjusting the threaded connection between the threaded shank 18 of the punch and the threaded bore 16 of the first portion. The pins 46 are spaced circumferentially about the length compensator, and serve not only to limit the upward travel of the portion 14, but also to maintain rotational alignment between the upper and lower portions.

Referring now to Figure 4, a punch tool of the invention is shown standing upright upon a surface S of a punch tool reservoir from which the punch tool is to be grasped and moved into position in the turret of a punch press using the autoload procedure described earlier. Because of the additional height of the tool (the axial distance between the annular surfaces 26 and 34 when they are spaced apart, as shown in Figure 4), the top of the tool can be suitably grasped by the robotic system. Once the tool is in position within the turret, a descending ram first encounters the ram-engaging surface 36. Further descent of the ram simply causes the springs 40 to compress and the second portion 14 to descend toward the portion 12 until the upper surface 36 of the second portion descends to the level of the ram-striking surface 60. At this point, the force of the ram against the surface 60 is transmitted to the end portion 18 of the punch, and a punching operation is begun. Alternatively, in a less preferred manner, the annular surfaces 26 and 34 may come into force transmitting contact before the ram can engage the surface 60, and ram force is transmitted from the second portion through the annular surfaces 26 and 34 to the first portion and thence to the end portion of the bunch tool to perform a punching operation. In either event, as the ram retreats upwardly, the punch returns upwardly to a rest position, and further elevation of the ram enables the second portion 14 to move upwardly under the influence of springs 40. When it is desired to remove the punching tool and replace it with another, the elevated position of the second portion 14 enables the tool to be readily grasped by the robotic system that is employed. If desired, the first and second portions of the length compensator may be made as a single unit, with neither portion movable with respect to the other. This embodiment is depicted in Figure 5. The length compensator, shown generally as 70, desirably is generally cylindrical in shape and has an internal, threaded bore 72 which receives the threaded shaft 18 of punch tool 20.

The compensator 70 includes a counterbore 74 at its upper end, that is, the end remote from the punch tool tip, the counterbore being of larger diameter that the threaded bore 72 to provide an internal annular shoulder 76 facing away from the tip of the punch tool. In this embodiment, the punch press ram (shown broken away as 80) is configured to be received in the counterbore 74 so that the ram, in its punching stroke, may strike the annular shoulder 76, the shoulder defining a ram-striking surface. The outer surface of the compensator at its upper end, which extends beyond the upper end of the threaded shaft 18, can be suitably grasped by the robotic tool transfer system. The ram and the counterbore are preferably circular in cross section but may be shaped as desired to enable the ram to extend into the counterbore to strike the shoulder 76 in a punching operation. Several forms of the invention have been shown and described, and other forms will now be apparent to those skilled in the art. It will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention defined the claims which follow.

Claims

1. Length compensator for a punch tool having a punch with a punch tip to facilitate use of the punch tool in an autoloading punch press utilizing a robotic tool transfer system to transfer punch tools into and out of the punch press, said compensator including a ram-striking surface positioned to be struck by a ram, said compensator having a first portion attachable to an end portion of the punch tool remote from the punch tip, and a second portion having an outer surface adapted to be gripped by a robotic transfer system, the second portion being carried by the first portion and extending beyond said ram-striking surface away from the punch tip to enable the second portion to be grasped by the robotic transfer system.

2. The length compensator of claim 1 including adjustment means for adjusting the position of the first portion lengthwise of the punch tool.

3. The length compensator of claim 2 including means for locking said first portion to the end portion of the punch tool.

4. The length compensator of claim 1 wherein said second portion includes an upper ram-engaging surface, the second portion being movably attached to the first portion to enable movement of the second portion lengthwise of the punch tool by ram force between a first position in which the first and second portions are spaced from each other a predetermined distance to increase the effective length of the punch tool to enable it to be grasped by the robotic transfer system, and a second position nearer the punch tip and enabling ram force to be transferred to said end portion of the punch tool in a punching operation, and spring means for urging the second portion into said first position.

5. The length compensator of claim 3 wherein said first portion is internally threaded to receive a threaded length of a punch remote from the workpiece- contacting surface thereof, and wherein said locking means comprises means preventing rotation of said first annular portion with respect to the threaded punch length.

6. The length compensator of claim 4 wherein said first and second portions have confronting, load transferring surfaces oriented to come into load transferring contact when said second portion is in its second position to enable the force of the ram to be transmitted through said portions to said end portion of said punch tool in a punch operation.

7. The length compensator of claim 1 for use with a punch tool, said first portion having an annular portion extending toward said second portion and terminating in a ram-striking surface, wherein said second portion, when in its second position, exposes said ram-striking surface to enable it to be directly struck by a ram.

8. The length compensator of claim 6 wherein said second portion includes a central opening telescopically receiving the annular portion of the first portion to enable movement of the second portion with respect to the first portion.

9. The length compensator of claim 4 including stop means preventing movement of said second portion away from said first portion further than said first position.

10. The length compensator of claim 9 wherein said stop means comprises a plurality of pins extending lengthwise of the punch tool and spaced circumferentially of the first annular portion, said pins extending from one of the portions and passing through openings formed in the other portion.

11. The length compensator of claim 10 wherein said pins extending through said other portion have enlarged ends preventing then from escaping through said holes as the second portion is urged away from the first portion.

12. The length compensator of claim 4 in which said spring means comprises a plurality of circumferentially spaced helical compression springs extending between said first and second portions.

13. A length compensator for a punch tool having a punch with a punch tip to facilitate use of the punch tool in an autoloading punch press utilizing a robotic tool transfer system to transfer punch tools into and out of the punch press, comprising: a. a first annular portion having an internally threaded bore within which may be received a threaded end portion of the punch tool remote from the tip of the punch, said first portion being adjustable lengthwise of the tool by rotating the first annular portion with respect to the end portion of the punch tool and terminating in a ram-striking surface oriented to face away from the punch tip, b. a second annular portion positioned to be further from the work contacting surface than the first portion when the latter is mounted to a punch tool, the second portion having an upper ram-striking surface and being movably attached to the first portion to enable movement of the second portion lengthwise of the punch tool between a first position in which the first and second portions are spaced from each other a predetermined distance and a second position exposing the ram- striking surface of the first portion to a ram to transfer ram force to the punch tip, and c. spring means urging the second portion into said first position.

14. The length compensator of claim 13 wherein said second portion includes a central opening telescopically receiving the annular portion of the first portion to enable movement of the second portion with respect to the first portion.

15. The length compensator of any of claims 1 and 13 wherein said ram-striking surface comprises an annular surface having an outer diameter that is less than the greatest width of said second portion measured normal to the length direction of the punch tool.

16. A length compensator for a punch tool having a punch with a punch tip to facilitate use of the punch tool in an autoloading punch press utilizing a robotic tool transfer system to transfer punch tools into and out of the punch press, comprising a portion having a first portion attachable to an end portion of the punch tool remote from the punch tip and a second portion having an outer surface adapted to be gripped by a robotic transfer system, the portion including an inner bore having an internal annular shoulder spaced from the end of the bore and defining a ram-striking surface facing away from the punch tip.

17. A punch tool including a length compensator to lengthen the punch tool so that it can be grasped by a robotic tool transfer system of an autoload punch press, the punch tool including a punch with a punch tip and an end portion remote from the punch tip, the length compensator comprising a first portion attached to said end portion of the punch tool, a second portion carried by the first portion and positioned further from the punch tip than the first portion, said compensator including a ram- striking surface facing away from said punch tip, said second portion extending away from the punch tip beyond said ram-striking surface to provide added length to said punch tool.

18. The punch tool of claim 17 including adjustment means for adjusting the position of the first portion lengthwise of the punch tool.

19. The length compensator of claim 18 including means for locking said first portion to the end portion of the punch tool.

20. The length compensator of claim 17 wherein said second portion includes an upper ram-engaging surface, the second portion being movably attached to the first portion to enable movement of the second portion lengthwise of the punch tool by ram force between a first position in which the first and second portions are spaced from each other a predetermined distance to increase the effective length of the punch tool to enable it to be grasped by the robotic transfer system, and a second position nearer the punch tip and enabling ram force to be transferred to said end portion of the punch tool in a punching operation, and spring means for urging the second portion into said first position.

21. The length compensator of claim 20 wherein said first portion is internally threaded to receive a threaded length of a punch remote from the workpiece- contacting surface thereof, and wherein said locking means comprises means preventing rotation of said first annular portion with respect to the threaded punch length.

22. A punch tool including a length compensator to lengthen the punch tool so that it can be grasped by a robotic tool transfer system of an autoload punch press, the punch tool including a punch with a punch tip and an end portion remote from the punch tip, a first portion attached to said end portion of the punch tool, a second portion mounted to the first portion and positioned further from the punch tip than the first portion, the second portion having an upper ram-engaging surface and being movably attached to the first portion to enable movement of the second portion lengthwise of the punch tool by ram force between a first position in which the first and second portions are spaced from each other a predetermined distance to increase the effective length of the punch tool to enable it to be grasped by the robotic transfer system, and a second position nearer the punch tip and enabling ram force to be transferred to said end portion of the punch tool in a punching operation, and spring means for urging the second portion into said first position.

23. The punch tool of claim 22 wherein said first portion is internally threaded to receive a threaded length of said end portion of said punch tool, and wherein said locking means comprises means preventing rotation of said first portion with respect to said end portion.

24. The punch tool of claim 22 wherein said first portion has a ram-striking surface, and wherein said second portion is movable lengthwise of the punch tool sufficiently so that the second portion, when in its second position, exposes said ram-striking surface to be directly struck by a ram.

25. The punch tool of claim 24 wherein said first and second portions have confronting, load transferring surfaces that come into load transferring contact when said second portion is in its second position to enable the force of the ram to be transmitted through said portions to said end portion of said punch tool in a punching operation.

26. The punch tool of claim 18 wherein said first portion extends toward said second portion and terminates in said striking surface, and wherein said second portion includes a central opening telescopically receiving said first portion to enable telescopic movement therebetween.

27. The punch tool of claim 14 including stop means preventing movement of said second portion away from said first portion further than said first position.

28. The punch tool of claim 24 wherein said stop means comprises a plurality of pins extending lengthwise of the punch tool and spaced circumferentially of the first annular portion, said pins extending from one of the portions and passing through openings formed in the other portion.

29. The punch tool of claim 28 wherein said pins extending through said other portion have enlarged ends preventing then from escaping through said holes as the second portion is urged away from the first portion.

30. The punch tool of claim 22 in which said spring means comprises a plurality of circumferentially spaced helical compression springs extending between said first and second portions.

31. A punch tool including a length compensator to lengthen the punch tool so that it can be grasped by a robotic tool transfer system of an autoload punch press, the punch tool having a punch with a punch tip at one end, the punch tool having a threaded end portion at the other end thereof, said length compensator comprising a first, generally annular portion having a threaded internal bore threaded onto the threaded end portion of the punch tool, a second generally annular portion positioned further from the work contacting surface than the first portion and having a ram-engaging surface, said portions having confronting contact surfaces, spring means urging the second portion lengthwise of the punch tool away from the first portion to increase the length of the punch tool, and stop means limiting such movement, whereby, when the second portion is spaced from the first portion, the length of the punch tool is increased sufficiently to enable it to be gripped by the robotic transfer system, and whereby the second portion, upon being struck by a ram, moves into contact with the first portion to transfer the load of the ram to the threaded end portion of the punch.

32. A punch tool including a length compensator to lengthen the punch tool so that it can be grasped by a robotic tool transfer system of an autoload punch press, the punch tool having a punch with a punch tip at one end, the punch tool having a threaded end portion at the other end thereof, said length compensator comprising a first, generally annular portion having a threaded internal bore threaded onto the threaded end portion of the punch tool and terminating in a ram-striking surface facing away from the punch tip, a second generally annular portion positioned further from the work contacting surface than the first portion and telescopically movable with respect to the first portion, spring means urging the second portion lengthwise of the punch tool away from the first portion to increase the length of the punch tool sufficiently to enable it to be gripped by a robotic transfer system, and stop means limiting such movement, said second portion being movable lengthwise of the punch tool toward said punch tip sufficiently to expose the ram-striking surface of the first portion to enable it to be directly struck by a ram.