WO2002009897A1

WO2002009897A1 - Press die assembly and method of using same

Info

Publication number: WO2002009897A1
Application number: PCT/US2001/041507
Authority: WO
Inventors: William V. Diedrick
Original assignee: D & D Manufacturing, Inc.
Priority date: 2000-07-31
Filing date: 2001-07-31
Publication date: 2002-02-07
Also published as: AU2001283526A1; WO2002009897A8

Abstract

A press assembly (10) includes an engagement member (28) movable toward a workpiece (11) to contact the workpiece (11) and to secure a portion of the workpiece against the press assembly (10), and a rotatable member (18) movable toward the workpiece (11) for bending the workpiece (11), the rotatable member (18) being spaced apart from the engagement member (28) with the engagement member (28) contacting and securing the portion of the workpiece (11) against the press assembly (10). A method of using the assembly is included.

Description

PRESS DIE ASSEMBLY AND METHOD OF MAKING SAME

FIELD OF THE INVENTION

This invention relates to an apparatus and method for forming sheet metal or like material, specifically, to an improved rotary bending apparatus and method of using the apparatus.

BACKGROUND OF THE INVENTION

Rotary bending tools for use in forming presses are known, for example, from Randolph, Sr., U.S. Patent No. 4,002,049. Typically, the rotary bending tool has a bending head rotatably mounted in a saddle attached to the ram of the press brake for movement toward and away from a cooperating forming anvil of a die section, for the purpose of folding or bending sheet material between the bending tool and the anvil. The bending head is generally cylindrical and has a longitudinally extending V-shaped notch incorporated therein. The two regions in which the walls of the V-shaped notch intersect the cylindrical outer wall of the bending head define a pair of lobes.

As stated above, the die section of the press contains an anvil upon which a workpiece rests. The anvil supports one portion of the workpiece while the other portion of the workpiece is unsupported. When the press is actuated, the ram containing the rotary bending tool moves toward the anvil and workpiece positioned thereon until a leading edge of the first lobe of the bending head makes contact with the supported portion of the workpiece while the second lobe makes contact with the unsupported portion of the workpiece. As the anvil supporting the workpiece acts to resist further downward motion of the bending head, contact of the first lobe with the supported portion of the workpiece initiates a rotation of the bending head. The rotation of the bending head occurs within the saddle and with respect to the leading edge of the first lobe, as the bending head continues to move downward and the second lobe continues to exert force on the unsupported portion of the workpiece. This rotational motion of the second lobe with respect to the first lobe causes the unsupported portion of the workpiece to bend about the anvil.

Many of the metal components formed using a rotary bending tool are incorporated into final products in which the formed metal component is visible to an end user of the product. Where these formed metal components are visible to an end user, the appearance of the components becomes extremely important, especially where the components are incorporated into consumer goods, such as VCR housings, cable television switch boxes or microwave ovens. Also, components which are visible to a user after assembly into a final product may be exposed to humid or corrosive environmental conditions.

Metal surfaces that will be visible to an end user or exposed to damaging environments in their finished form frequently undergo a secondary operation after forming in which one or more layers of paint, plating, coating or other surface treatment are applied in order to improve part appearance, surface finish, and to prevent corrosion. However, application of paint or surface treatments to metal components after forming is relatively costly due to the additional handling necessary for processing individual formed components. Therefore, it would be advantageous from a cost perspective to form pre-treated (i.e., pre-painted, pre-plated, etc.) metal stock.

One problem encountered in using a rotary bending tool to form pre-treated stock is that the resistance to downward motion of the bending head provided by the anvil causes the first lobe of the bending head to dig into the surface of the relatively unyielding, supported portion of the workpiece just prior to rotation of the bending head, leaving impact marks on the pre-treated surface of the workpiece. Impact marks on a pre-treated surface will adversely affect its appearance and may also damage the integrity of any previously applied plating or surface coating. For this reason, it has not proven feasible to form stock having pre-treated surfaces using a conventional rotary bending tool. SUMMARY OF THE INVENTION

In accordance with the present invention, a press assembly having a rotatable member which is movable toward a workpiece for bending a workpiece comprises an engagement member for contacting a portion of the rotatable member at a position spaced apart from the workpiece, in which rotation of the rotatable member is facilitated with the portion of the rotatable member in contact with the engagement member and with the rotatable member in motion toward the workpiece enabling another portion of the rotatable member to engage the workpiece.

An object of this invention is to provide a method for bending a workpiece with a rotatable member in a press assembly, including the steps of positioning an engagement member in contact with a portion of the rotatable member at a position spaced apart from the workpiece and moving the rotatable member toward the workpiece with the portion of the rotatable member in contact with the engagement member, facilitating rotation of the rotatable member enabling another portion of the rotatable member to engage the workpiece for bending the workpiece.

Another object of the invention is to provide a simple, efficient means for bending a workpiece with or without a pre-treated surface without imparting damage to the workpiece surface or treated surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side elevational view of a press assembly incorporating the present invention;

Fig. 2 is enlarged and partially cut away view of the press assembly shown in Fig. 1 prior to actuation of a press ram;

Fig. 3 is the view of Fig. 2 showing the downward progression of the rotatable bending member and engagement member after actuation of the press ram;

Fig. 4 is the view of Fig. 2 showing the engagement member in contact with a supported portion of the workpiece and the continuing downward progression of the rotatable bending member; Fig. 5 is the view of Fig. 2 showing a first lobe of the rotatable bending member engaging the engagement member as downward progression of the rotatable bending member toward the workpiece continues;

Fig. 6 is the view of Fig. 2 showing the rotatable bending member in rotation with rotatable bending member in contact with and bending the workpiece;

Fig. 7 is the view of Fig. 2 showing the ram at the limit of its downward stroke and the rotatable bending member at the limit of its rotational movement, at which point the desired bend in the workpiece has been achieved.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Figs. 1 and 5, a press assembly 10 incorporates an embodiment of the present invention. Press assembly 10 may be a stand alone unit or constitute part of a progressive die system in which various stamping and/or forming operations have been performed on workpiece 11 prior to advancement of workpiece 11 to the bending station press assembly discussed in detail below.

Press assembly 10 comprises a ram 12 and a stationary bed 34 underlying ram 12. An upper die shoe 14 is affixed to ram 12. A punch retainer 15 is affixed to upper die shoe 14. As is known in the art, punch retainer 15 is adapted for accommodating a variety of mounting structures for various types of punches and forming tools. A shaft 90 extends through both punch retainer 15 and upper die shoe 14 for receiving a compression spring 44. As seen in Fig. 5, compression spring 44 is constrained at one end of shaft by ram 12 where upper die shoe 14 is attached to ram 12. An opposite end of compression spring 44 rests on engagement member 28. Spring 44 is always in a state of compression. A lower die shoe 36 is affixed to press bed 34. A die retainer 37 is mounted to lower die shoe 36. As is known in the art, die retainer 37 is adapted for accommodating a die set which complements the punch or forming tool mounted on punch retainer 15 for performing a predetermined operation on workpiece 11. As seen in Fig. 5, one or more bores 75 extend through both upper die shoe 14 and punch retainer 15 for receiving one or more engagement member retainers 60, in a manner described in more detail below. An upper section 80 of bore 75 has a greater diameter than the remainder of bore 75. The intersection of upper bore section 80 with the remainder of bore 75 defines a shoulder 85 located in upper die shoe 14. Since further details of the press are not necessary for an understanding of the invention, they are not illustrated.

Referring to Fig. 2, a mounting block 16 is affixed to punch retainer 15 for the rotatable mounting of a rotatable or bending member 18. Mounting block 16 of the present embodiment is configured for the rotatable mounting of a generally cylindrical shaped bending member 18.

Bending or rotatable member 18 may be rotatably mounted in mounting block 16 using one of many methods known in the art. Bending member 18 has a generally cylindrical body 52 modified by including a notch 56 which is coextensive with the length of cylindrical body 52 and defined by the outer peripheral surface 54 of rotatable member 18. A first sidewall 22 and a second sidewall 26 of notch 56 oppose one another and form a symmetrical "V", which is uniform in cross section for the length of the notch. Generally, the surfaces of first and second sidewalls 22, 26 are flat. The apex of the "V" is innermost of the body 52. The apex of the "V" is normally radiused, as is each of the junctions between each of the sidewalls 22 and 26 and the respectively adjacent portions of outer peripheral surface 54 of the body 52. The configuration of body 52 and notch 56 as above defines first and second lobes, 20 and 24, respectively, the outermost limits of which, with reference to a central longitudinal axis of the body 52, correspond, substantially, to the outermost limits of first and second sidewalls 26 and 22 and lie in and define a common plane.

A return mechanism (not shown) is incorporated into the mounting structure of bending or rotatable member 18. The return mechanism is designed to rotate bending member 18 to its pre-engagement orientation when engagement between bending member 18 and engagement member 28 (described in detail below) is broken.

Referring again to Fig. 2, a die set 38 is mounted on lower die shoe 36. Die set 38 is configured for complementary interengagement with rotatably mounted bending member 18 during cycling of the press. Die set 38 includes an anvil 40, one surface of which defines a desired bending profile 42 against which a workpiece 11 is urged by bending member 18 during cycling of the press in order to produce the desired bend. Workpiece 11 is positioned atop and substantially supported by die set 38. Workpiece 11 comprises in this example a pre-treated sheet material. Worlφiece 11 may be an individual component or part of an extended length of sheet material undergoing processing in a progressive die. Another portion 50 of workpiece 11 extends beyond an edge of anvil 40, overlying lower die shoe 36. Another portion 50 of workpiece 11 is, therefore, unsupported by die set 38. Portion 46 of worlφiece 11 is directly supported by die set 38.

Further referring to Figs. 1, 2 and 5, engagement member 28 is coupled to ram 12 via one or more engagement member retainers 60 so as to move in conjunction with ram 12. Engagement member retainer 60 has a head end 100, a lower end 120 and an elongated body 110 extending between the head and lower ends. Engagement member 28 is secured to lower end 120 of retainer 60. As seen in Fig. 5, body 110 of retainer 60 resides within bore 75 extending through punch retainer 15 and upper die shoe 14, and is slidable with respect to bore 75 during movement of press ram 12. In addition, head end 100 of retainer 60 is slidable within an upper section 80 of bore 75 during movement of ram 12. As will be discussed in more detail below, an engagement surface 30 of engagement member 28 provides a surface for contacting a portion 39 of bending member 18 as bending member is moved toward workpiece 11. Generally, engagement surface 30 is substantially flat. For reasons to be discussed in more detail below, in the present embodiment engagement member 28 is positioned with respect to bending member 18 such that engagement surface 30 directly overlies workpiece 11 and is interposed between portion 39 of bending member 18 and workpiece 11 along the direction of arrow "A", as seen in Figs. 2-7.

As seen in Figs. 3 and 4 of the present embodiment, bearing surface 32 is positioned on a side of engagement member 28 facing workpiece 11, in which engagement surface 30 discussed above is positioned on an opposite side of engagement member 28 . Bearing surface 32 is adapted for contacting workpiece 11 and securing workpiece 11 to die set 38 during the actual bending operation, in a manner also to be described in more detail below. As bearing surface 32 contacts the pre-treated surface of workpiece 11, bearing surface is a flat precision ground surface so that contact between engagement surface 30 and workpiece 11 will not damage the surface of workpiece 11.

Operation of press assembly 10 incorporating the present invention is shown in Figs. 3-7. In referring to Figs. 1 and 3, actuation of the press initiates a downward movement of ram 12 in the direction of arrow "A" toward workpiece 11 positioned atop die set 38. As described above, punch retainer 15 is affixed via die shoe 14, and mounting block 16, in which bending member 18 is rotatably mounted, is attached to punch retainer 15. Thus, as ram 12 moves in direction "A" toward workpiece 11, the attached bending member 18 also moves toward the workpiece. In addition, during the downward progression of ram 12 and before engagement member 28 makes contact with workpiece 46, engagement member 28 is supported by engagement between head end 100 of retainer 60 and shoulder 85. With engagement member 28 thus coupled to ram 12 to move in conjunction with ram 12, engagement member 28 moves downward toward workpiece 11 in association with bending member 18. The coupling of engagement member 28 to ram 12 maintains the spatial relationship between engagement member 28 and bending member 18 during downward motion of engagement member 28 toward workpiece 11.

Fig. 4 shows press assembly 10 at the point in the downward stroke of ram 12 at which bearing surface 32 of engagement member 28 makes contact with supported portion 46 of workpiece 11. When bearing surface 32 of engagement member 28 makes contact with supported portion 46 of workpiece 11, further downward movement of engagement member 28 is prevented. However, after engagement member 28 makes contact with supported portion 46 of workpiece 11, ram 12 continues its downward motion, bringing bending member 18 closer to inteφosed engagement surface 30 and workpiece 11.

Fig. 5 shows the press assembly at the point in the downward stroke of ram 12 at which portion 39 of bending member 18 at first lobe 20 proximate to notch 56 makes contact with engagement surface 30 of engagement member 28. This contact between first lobe 20 of bending member 18 and engagement surface 30 will initiate a rotation of bending member 18 in a manner known in the art. In this embodiment, rotatable or bending member 18 has an axis of rotation 41 and is rotatably mounted as mentioned above. As the ram strokes downwardly toward workpiece 11, the axis of rotation proscribes line 43. Line 43 is substantially traverse to workpiece 11. Moreover, portion 39 of rotatable or bending member 18 that contacts surface 30 of engagement member 28 is positioned spaced apart and not in alignment with the line 43 proscribed by the axis of rotation 41 moving toward the worlφiece. As portion 39 contacts surface 30, the downward progression of the ram causes rotatable or bending member 18 to rotate about axis 41 and about portion 39 of the rotatable member 18. Also at this point, head end 100 of retainer 60 begins to disengage from shoulder 85 as punch retainer 15 and upper die shoe 14 continue downward, head end 100 sliding within upper section 80 of bore 75. Simultaneously, spring 44 continues to compress further.

However, prior to initiation of bending member 18 rotating, there is an initial resistance to further downward motion of bending member 18 provided by supported portion 46 of workpiece 11. In a conventional rotary bending arrangement, this initial resistance to further downward motion of bending member 18 would cause portion 39 of first lobe 20 of bending member 18 to dig into a pre-treated surface of the relatively unyielding, supported portion 46 of workpiece 11 prior to initiation of rotation, leaving an unacceptable impact mark on the surface of workpiece 11.

In the arrangement of the present invention, however, portion 39 of first lobe 20 of bending member 18 makes contact with engagement surface 30 rather than the pre-treated surface of workpiece 11. Thus, resistance to further downward motion of bending member 18 is provided by engagement surface 30 rather than workpiece 11, and damage to the pre-treated surface of workpiece 11 is prevented.

In Fig. 6, rotation of bending member 18 has been initiated by contact of portion 39 of first lobe 20 and engagement surface 30 as ram 12 continues its downward stroke. Rotation of bending member 18 brings second lobe 24 or another portion of rotatable member 18 into engagement with the unsupported another portion 50 of workpiece 11. As the downward stroke of ram 12 continues, bending member 18 continues to rotate, forcing unsupported another portion 50 of workpiece 11 to bend about bending profile 42 of anvil 40. In Fig. 7, the press assembly 10 is at the limit of the downward stroke of ram 12. The downward stroke is controlled so as to stop when bending member first sidewall 22 of lobe 20 rests flush against engagement surface 30. At this point, the desired bend has been imparted to the workpiece.

At this point, ram 12 is retracted and spring 44 which was further compressed as discussed above now facilitates upward movement of upper die shoe 14, mounting block 16, rotatable member 18 and engagement member 28. Once the assembly is retracted, workpiece 11 can be removed and another positioned in its place.

The present invention provides a method, which is shown in Figs. 2-7, for bending workpiece 11 with a rotatable member 18 in press assembly 10, which includes the steps of positioning engagement member 18 in contact with portion 39 of rotatable member 18 at a position inteφosed between portion 39 of the rotatable member 18 and workpiece 11. The method also includes moving rotatable member 18 toward workpiece 11 with portion 39 of rotatable member 18 in contact with engagement member 28, facilitating rotation of rotatable member 18 enabling another portion 24 of the rotatable member 18 to engage workpiece 11 for bending workpiece 11.

Moreover, the method includes the step of positioning engagement member 28 to overlie a portion 46 of workpiece 11. In the embodiment shown herein, engagement member 28 is positioned in contact with portion 46 of workpiece 11 which is supported, hi this method, another portion 50 of the workpiece 11 is oriented in a position without support for engagement with the another portion or lobe 24 of rotatable member 18.

It can be seen from the above description that the method and apparatus of the present invention provide a simple, efficient means for bending a pre-treated workpiece without producing the surface damage to the worlφiece.

In alternative embodiments, various aspects of the invention may differ from the above description. For example, the engagement member may be moved independently of the ram. In another alternative embodiment, the engagement member may be configured so that the engagement surface is positioned such that it contacts a portion of the bending member and initiates rotation of the bending member prior to the bending member contacting the workpiece, while not directly overlying the workpiece. In addition, the engagement member may be positioned such that it does not contact the workpiece during operation. Furthermore, although a cylindrical bending member is shown in the embodiment described above, other bending members having alternative geometries may also be used provided they are capable of bei ^ rotatably mounted and are configured so that engagement between a first surface of the bending member and an engagement surface on the engagement member will initiate rotation of the bending member such that a second surface of the bending member acts to bend a portion of a workpiece.

While a detailed description of various embodiments of the present invention have been given, it should be appreciated that many additional variations can be made thereto without departing from the scope of the invention as set forth in the appended claims.

Claims

1. In a press assembly having a rotatable member which is movable toward a workpiece for bending a workpiece, comprising: an engagement member for contacting a portion of the rotatable member at a position inteφosed between the portion of the rotatable member and the workpiece, in which rotation of the rotatable member is facilitated with the portion of the rotatable member in contact with the engagement member and with the rotatable member in motion toward the workpiece enabling another portion of the rotatable member to engage the workpiece.

2. The press assembly of claim 1 in which the engagement member overlies a portion of the workpiece.

3. The press assembly of claim 1 in which a surface positioned on a side of the engagement member contacts the portion of the workpiece.

4. The press assembly of claim 3 in which the surface is substantially flat.

5. The press assembly of claim 3 in which the engagement member includes another surface for contacting the portion of the rotatable member.

6. The press assembly of claim 5 in which the other surface is positioned on an opposite side of the engagement member from the side of the surface.

7. The press assembly of claim 5 in which the other surface is substantially flat.

8. The press assembly of claim 1 in which the rotatable member has an axis of rotation.

9. The press assembly of claim 8 in which axis of rotation of the rotatable member proscribes a line as the rotatable die moves toward the workpiece.

10. The press assembly of claim 9 in which the line is substantially transverse to the workpiece.

11. The press assembly of claim 9 in which the portion of the rotatable member that contacts the engagement member is positioned spaced apart from and out of alignment from the line.

12. The press assembly of claim 1 in which the rotatable member is formed generally cylindrical in shape with a notch defined by the rotatable member positioned along a length of the cylindrical shape.

13. The press assembly of claim 12 in which the notch includes two opposing sidewalls.

14. The press assembly of claim 13 in which the sidewalls are substantially flat.

15. The press assembly of claim 13 in which the two opposing sidewalls form generally a "V"-shape.

16. The press assembly of claim 12 in which the portion of the rotatable member is positioned on the surface of the cylindrical shape and proximate to the notch.

17. In a method for bending a workpiece with a rotatable member in a press assembly, including the steps of: positioning an engagement member in contact with a portion of the rotatable member at a position inteφosed between the portion of the rotatable member and the workpiece; moving the rotatable member toward the workpiece with the portion of the rotatable member in contact with the engagement member, facilitating rotation of the rotatable member enabling another portion of the rotatable member to engage the worlφiece for bending the workpiece.

18. The method of claim 17 includes the step of positioning the engagement member to overlie a portion of the workpiece.

19. The method of claim 17 includes the step of positioning engagement member in contact with a portion of the workpiece which is supported.

20. The method of claim 19 includes the step of orienting another portion of the workpiece in a position without support for engagement with the another portion of the rotatable member. AMENDED CLAIMS

[received by the International Bureau on 30 October 2001 (30.10.01); original claims 1-20 cancelled; new claims 21-40 added (2 pages)]

21. A press assembly comprising: an engagement member movable toward a workpiece to contact the workpiece and to secure a portion of the workpiece against the press assembly; and a rotatable member movable toward the workpiece for bending the workpiece, the rotatable member being spaced apart from the engagement member with the engagement member contacting and securing the workpiece against the portion of the press assembly.

22. The press assembly of claim 21 in which the engagement member overlies a portion of the workpiece.

23. The press assembly of claim 21 in which a surface of a side of the engagement member contacts a portion of the workpiece.

24. The press assembly of claim 23 in which the surface is substantially flat.

25. The press assembly of claim 23 wherein the engagement member includes another surface for contacting the rotatable member with the engagement member in contact with the workpiece.

26. The press assembly of claim 25 in which the other surface is positioned on an opposite side of the engagement member from the side.

27. The press assembly of claim 25 in which the other surface is substantially flat.

28. The press assembly of claim 21 in which the rotatable member is formed generally cylindrical in shape with a notch defined by the rotatable member positioned along a length of the cylindrical shape.

29. The press assembly of claim 28 in which the notch includes two opposing sidewalls.

30. The press assembly of claim 29 in which the sidewalls are substantially flat.

31. The press assembly of claim 29 in which the two opposing sidewalls form generally a "V"-shape.

32. The press assembly of claim 21 in which the rotatable member has an axis of rotation.

33. The press assembly of claim 32 in which axis of rotation of the rotatable member proscribes a line as the rotatable die moves toward the workpiece.

34. The press assembly of claim 33 in which the line is substantially transverse to the workpiece.

35. The press assembly of claim 33 in which a portion of the rotatable member which contacts the engagement member is positioned spaced apart from and out of alignment from the line.

36. The press assembly of claim 35 wherein another portion of the rotatable member which contacts the workpiece for bending the workpiece is positioned on an opposite side of the proscribed line from the portion.

37. The press assembly of claim 36 in which the portion and the other portion of the rotatable member are positioned on the surface of the cylindrical shape and proximate to the notch.

38. In a method for bending a workpiece with a rotatable member in a press assembly, including the steps of: positioning an engagement member to contact the workpiece and to secure a portion of the workpiece to the press assembly; and moving the rotatable member from a position spaced apart from the engagement member toward the engagement member to contact the engagement member to facilitate rotation of the rotatable member to enable another portion of the rotatable member to engage the another portion of the workpiece for bending the workpiece.

39. The method of claim 38 wherein the step of positioning a portion of the rotatable member in contact with the engagement member includes positioning the engagement member in contact with the portion of the workpiece which is supported.

40. The method of claim 38 including the steps of: moving the rotatable member to a position spaced apart from the engagement member; and moving the engagement member out of contact with the workpiece to a position spaced apart from the rotatable member.