Sheet material with bend controlling displacements and method for forming the same
A method of preparing a sheet of material for bending along a bend line comprising the step of forming of at least one displacement in the thickness direction of the sheet of material with a portion of the periphery of the displacement closest to the bend line providing an edge and opposed face configured in position to produce edge-to-face engagement of the sheet on opposite sides of the periphery during bending. The forming step is preferably accomplished using one of a stamping process, a punching process, a roll-forming process and an embossing process. A sheet of material suitable for bending using the process also is disclosed, as are the use of coatings, shin guards and displacing the area of the sheet between bending inducing slits.
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This application is a Continuation-in-Part Application based upon a co-pending patent application Ser. No. 10/672,766 filed Sep. 26, 2003 and entitled TECHNIQUES FOR DESIGNING AND MANUFACTURING PRECISION-FOLDED, HIGH STRENGTH, FATIGUE-RESISTANT STRUCTURES AND SHEET THEREFOR, which was a Continuation-in-Part Application based upon a co-pending patent application Ser. No. 10/256,870, filed Sep. 26, 2002, and entitled METHOD FOR PRECISION BENDING OF SHEET MATERIALS, SLIT SHEET AND FABRICATION PROCESS, which was a Continuation-in-Part Application based upon co-pending parent application Ser. No. 09/640,267, filed Aug. 17, 2000, and entitled METHOD FOR PRECISION BENDING OF A SHEET OF MATERIAL AND SLIT SHEET THEREFOR, now U.S. Pat. No. 6,481,259 B1.
TECHNICAL FIELDThe present invention relates, in general, to the precision folding of sheet material and, more particularly, relates to preparing the sheet material for bending using punching, stamping, roll-forming, embossing and similar processes, and then bending or folding the sheet into three-dimensional structures.
BACKGROUND ARTThe present method and apparatus are based upon slitting and grooving geometries disclosed in depth in the above set forth related applications, which are each incorporated herein by reference in their entireties. In these related applications several techniques or manufacturing processes for forming slits and grooves that will precisely control bending of a wide variety of sheet material are disclosed, including laser cutting, water jet cutting, stamping, punching, molding, casting, stereo lithography, roll forming, machining, chemical-milling, photo-etching and the like. Some of these processes for fabricating bend-inducing slit geometries can be more expensive than others. For example, laser cutting will inherently involve additional cost as compared to, for example, punching or stamping, but punching and stamping may not be particularly well suited to sheet material of relatively heavy gauge.
The precision bending slit geometries of the above-identified related applications may be advantageously applied to numerous structures which are formed from relatively thin gauge sheet material. These structures tend to be more driven by the need for complex and precise bending patterns than they are by strength or fatigue resistance requirements. An example of one type of structure which can be formed of a relatively thin gauged sheet material, and yet requires precision and complex bending, is electronic component chassis, such as, computers, audio receivers, television sets, DVD players, etc.
As is noted in prior related application Ser. No. 10/672,766, flat sheets, which are slit or grooved in accordance with the teachings of that prior related application, can have electrical components mounted to the flat sheets using “pick-and-place” techniques. The sheets may then be folded into enclosures or housings in which all of the components are spatially related in the desired positions inside the housing. The “pick-and-place” techniques greatly reduce cost, as does the ability to fold a flat sheet into a precisely dimensioned enclosure using relatively low-force bending techniques. While such electronic chassis can be formed using laser cutting or water jet cutting, there is considerable advantage if lower cost slit-forming or groove-forming techniques can be employed. Thus, lower cost fabrication processes such as punching, stamping, roll-forming or the like, will be highly advantageous to use with relatively thin gauge material if they do not lose the precision advantages that the slits geometries of the related applications can produce.
Moreover, slit-forming techniques, such as punching, stamping and roll-forming, can produce slits which have essentially zero kerf or slit width dimension, while laser and water jet cutting remove material and product slits having a measurable kerf or width dimension. Sheets having zero kerf slits have the advantage of being more closed along the bend line after the sheets are bent. Thus, they do not tend to open up as much during bending as sheets having measurable kerf dimensions. This makes the zero kerf sheets amenable to coating with a protective layer that will seal and close the bend line to allow them to be used in applications in which electromagnetic shielding is required or in which, corrosion resistance, attractive appearance, fluids need to be contained.
Accordingly, it is an object of the present invention to provide a method for preparing sheet material for precision bending along a bend line, which method is relatively low in cost and which adaptable to a wide range of applications employing sheet material.
A further object of the present invention is to provide a low cost method for preparing sheet material for bending, which method is capable of precise bending free of cumulative bending errors, is suitable for complex bending patterns, and requires only minimal force to effect bending.
Another object of the present invention is to provide a sheet of material for bending in which slits or grooves are formed using low-cost manufacturing processes that are capable of producing structures which can be sealed, are fluid-tight, corrosion resistant or must have an attractive appearance.
The bendable sheet material and bend-inducing sheet forming method of the present invention have other objects and features of advantage which will be set forth in more detail hereinafter in the following Best Mode of Carrying Out the Invention, as exemplified and illustrated by the accompanying drawing.
DISCLOSURE OF THE INVENTIONThe method of preparing a sheet of material for bending along a bend line of the present invention is comprised, briefly, of the step of forming at least one displacement in the thickness direction of the sheet of material with the portion of the periphery of the displacement closest to the bend line providing an edge and an opposed face configured and positioned to produce edge-to-face engagement of the sheet of material during bending. The displacement is preferably formed using one of a punching, stamping, roll-forming, embossing, chemical milling or etching process in which dies, machine tools, a knife or chemical agent form a slit or shear line of zero kerf or a groove in the sheet material. When dies are employed, the periphery of the displacement caused by the die, which is closest to the bend line is sheared at least partially, and often completely, through the thickness dimension of the sheet of material proximate the bend line. Most preferably, a plurality of displacements are formed along the bend line, with alternate displacements being positioned on opposite sides of the bend line. In the most preferred form the periphery which is closest to the bend line is, in fact, superimposed on the bend line so that the jog distance between displacements on opposite side of the bend line is essentially zero. The displacements, however, can have a jog distance in the range of about −0.5 to about +0.5 times the thickness dimension of the sheet. The displacements also may be plastically deformed by die sets to produce the opposing edge and face structures. Upon bending, the sheet of material may not fracture or rupture along the plastically deformed displacements, so that the bend will be maintained as a fluid-tight continuous structure along the bend line, or it may rupture to provide a face and opposed edge similar to sheared sheets. While it is preferred to displace the tongues which are defined inside the slits or grooves, it also is possible to displace the areas longitudinally between the slits or groove and still achieve edge-to-face precision bends. Moreover, the bending direction is preferably in the direction of displacement of the tongues, but if lower precision can be tolerated bending can be in the opposite direction.
A sheet of material suitable for bending along a bend line is also provided which comprises, briefly, a sheet having at least one displacement in the thickness direction of the sheet, with a portion of the displacement closest to the bend line providing an edge and an opposing face configured to produce edge-to-face engagement of the sheet of material on opposed sides of the portion of the periphery during bending. Most preferably a plurality of displacements are positioned along the bend line on alternating sides of the bend line. A continuous layer of coating material can be placed on the sheet before bending to further insure that resulting bend will be fluid-tight, corrosion resistant and attractive. The displacements in the sheet of material can extend partially through the sheet or completely through it, and the sheet can be bent in the direction of the displacements for maximum precision or in an opposed direction by relying on the oblique bending straps to control the precision. Optionally, but less desirably, the sheet may be bent in the opposite direction when the precision achievable by edge-to-face bending is not required.
DESCRIPTION OF THE DRAWING
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to those embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention, as defined by the appended claims.
The present method and apparatus for precision bending of sheet material is based upon the slitting geometries disclosed in the above-identified prior related applications, which are incorporated herein by reference in their entireties.
As noted in connection with the prior related applications, processes for forming the slits which will control and precisely locate the bending of sheet material include such processes as punching, stamping, roll-forming, machining, photo-etching, chemical machining and the like. These processes are particularly well suited for lighter weight or thinner gauge material, although they also can be employed for sheet material of relatively heavy gauge. The thicker or heavier gauged materials often are more advantageously slit or grooved using laser cutting or water jet cutting equipment.
As described in the prior related applications, one highly advantageous application for the precision bending of sheet material is in connection with electronic component chassis. Such chassis often are highly complex so as to enable the positioning of a multiplicity of components in three-dimensional arrays inside the eventual housing for the electronic equipment. Since laser cutting and water jet cutting are both somewhat more expensive, it is particularly desirable to be able to form chassis for electronic equipment, and numerous other lower cost housings and the like, using-low cost, high-production techniques such as punching, stamping, roll forming and the like. The present application, therefore, illustrates how these lower cost fabrication processes can be applied to relatively thinner gauged sheet material with great advantage.
Turning now to
As also may be seen in
As described in prior related application Ser. No. 10/672,766, the “jog” distance between slits 22 is defined as the lateral distance between the slits on opposite sides of the bend line. In the most preferred form of the embodiments in the present application, therefore, the jog distance is substantially equal to zero, that is, the slits are positioned precisely on bend line 23 so that there is no lateral spacing between slits on the opposite sides of the bend line, except at the curved ends. As indicated in the prior related applications, the jog distance between slits relative to bend line 23 is preferably less than the thickness dimension of sheet 21. Obviously, a jog distance of zero meets that requirement.
Additionally, as can be seen for slits 22a and 22b at the right hand end of sheet 21, a negative jog distance also can be employed. As will be seen, slit 22a extends across bend line 23, as does slit 22b. This is acceptable within the teaching of the present invention and will produce the edge-to-face bending along bend line 23 that is desired for precise, controlled bending. For the thinner gauged materials typically employed in electronic equipment chasses, the jog distance between slits 22 is preferably in the range of about −0.5 to about +0.5 times the thickness dimension, t, (
When a negative jog distance is employed with slits 22 having a zero kerf dimension, the slit will remain relatively closed along its length even after a 90 degree bend. If the slit is formed with a kerf, for example, by laser cutting, and a negative jog distance is employed, there is a tendency for the material on opposite sides of the slit to separate or “daylight” upon bending, for example, to 90 degrees. This, however, can be entirely acceptable, depending upon the application.
As will be described in considerable detail below, the most preferred approach to punching or stamping slits into sheet 21 is to displace a tongue or enclosed area of slug in the thickness direction of the sheet by dies which shear the sheet. It will be understood from prior related applications, however, that slits 22 also can be formed as shear lines or slits in which there is no displacement of the sheet, for example, by using a knife, rather than a die that also displaces a portion of the sheet. One of the advantages of forming a displacement in the sheet, rather than slitting it with a knife, is that edge-to-face sliding of material on opposite sides of slits 22 is reduced or not required. The displacement of the sheet also reduces the bending forces required by insuring that each edge and face will move in the right direction during bending.
In the preferred form, slits 22 are formed by displacement in a thickness direction so that a portion of the periphery of the displacement closest to bend line 23 provides an edge 26 and an opposed face 27 configured and positioned to produce edge-to-face engagement of the sheet of material on opposite sides of the periphery during bending. As shown in
When sheet 21 is bent, for example, by 90 degrees, edges 26, 26a pivot around and engage faces 27,27a at about a midpoint in the faces. As bending continues, they act as opposed fulcrums which are positioned on bend line 23 (that can be seen in
The illustrations in
As will be seen from
In cases where full coverage of both sides of the street with a flexible sealing coating is desired, one generally applies (prior to bending) a flexible coating 29 to both sides of the sheet in the embodiment of bent D-shaped tongues 28 as shown in
As will be apparent to one skilled in the art, the displacement or tongues 28 of
In
In
In the embodiment of
Turning now to
In
In
In
Although not shown, oval displacements or slugs 71 and 81 also can be completely punched or stamped out of sheet 21 to leave oval holes along the sheet. Such holes will define obliquely extending bending straps 24 skewed in opposite directions at opposite ends of each of the holes. These bending straps extend across the bending line 23 and will again produce bending along bending line 23, but without edge-to-face engagement because the slug faces 27 are now gone. While providing less precision, such an embodiment will produce reasonably accurate bending along bending line 23.
In
In
In
One of the important features of the slit or displacement geometries described in this application, and the prior related applications, is that folding of the sheet of material requires relatively small forces. Bending straps 24 preferably comprise less than a majority of the material along the bend line and they are twisted and bent during bending of the sheet material. The fulcrum between edge 26 and face 27 and the long lever arm of the sheet on both sides of the bend line, makes bending of the sheet with relatively low force very simple. It is possible, for example, to place an edge of the sheet in a slot or groove and then manually apply a force to the opposite edge to easily bend the sheet. In most cases where the sheet material would be bent for an electronic chassis, the sheet can be bent by hand. It is most preferred, however, to be able to perform the bending in an automatic machine-implemented process, for example, in a progressive die assembly in which the sheet is prepared for bending at a first station by forming displacements along the bend line, and the sheet is thereafter moved to another station and then bent by relatively low-force bending apparatus.
FIGS. 12A-C show a mechanical bending apparatus in which a fixed tool plate 110 supports a sheet 21, which has been prepared for bending in the manner described above. A bending cylinder 111 is mounted to a movable linkage or arm 112 for downward displacement, as shown by arrow 113. As cylinder 111 is brought down against sheet 21, an edge 114 of a notch 116 in the cylinder engages sheet 21 and begins to rotate the cylinder and linkage 112 in a clockwise direction. As the linkage 112 continues to move downwardly, cylinder 111 continues to rotate to the position 21 so as to form shown in
An alternative approach shown in
Other bending equipment suitable for use for bending the sheets of the present invention would include a press brake.
In
In
In this regard, it should be noted that the embodiments of the present invention shown in
Sheet 221 of
Turning now to
Unlike the embodiments previously described, however, D-shaped tongues 328 are not displaced but remain in the plane of sheet 321. Instead, the material or area 330 longitudinally adjacent to or between tongues 328 on the same side of bend line 323 is upwardly displaced, as best may be seen in
As was above described in connection with the other embodiments, the embodiment of
Claims
1. A method of preparing a sheet of material for bending along a bend line comprising the step of:
- forming at least one displacement in the thickness direction of the sheet of material with a portion of the periphery of the displacement closest to the bend line providing an edge and an opposed face configured and positioned to produce edge-to-face engagement of the sheet of material during bending.
2. The method as defined in claim 1 wherein,
- the forming step shears the sheet of material partially through its thickness dimension along the portion of the periphery.
3. The method as defined in claim 2 wherein,
- the forming step shears the sheet of material sufficiently through the thickness dimension along the portion of the periphery to produce fracturing through the entire thickness dimension of the sheet of material upon bending.
4. The method as defined in claim 2 wherein,
- the forming step shears the sheet of material entirely through the thickness dimension along the portion of the periphery.
5. The method as defined in claim 1 wherein,
- the forming step plastically deforms the sheet of material to provide an edge and an opposed face configured so as not to fracture through the thickness dimension upon bending of the sheet material.
6. The method as defined in claim 1 wherein,
- the forming step is accomplished using one of a stamping process, a punching process, a roll forming process, a shearing knife-based and an embossing process.
7. The method as defined in claim 1 wherein,
- during the forming step, forming a plurality of displacements in the sheet of material along the bend line with each displacement having a periphery portion proximate the bend line to provide a plurality of edges and opposed faces for edge-to-face bending of the sheet of material.
8. The method as defined in claim 7 wherein,
- during the forming step, forming the plurality of displacements along the bend line with each displacement having the periphery portion substantially superimposed on the bend line.
9. The method as defined in claim 7 wherein,
- during the forming step, forming a plurality of displacements in the sheet of material with the periphery portion of at least one displacement being positioned on each side of the bend line.
10. The method as defined in claim 9 wherein,
- during the forming step, positioning the periphery portion of displacements on opposite side of the bend line at a jog distance from each other less than the thickness dimension of the sheet of material.
11. The method as defined in claim 10 wherein,
- the jog distance is in the range of about −0.5 to about +0.5 times the thickness dimension of the sheet of material.
12. The method as defined in claim 9 wherein,
- during the forming step, forming the peripheral portions of displacements on opposite sides of the bend line to define bending straps oriented to extend obliquely across the bend line.
13. The method as defined in claim 1 wherein,
- during the forming step, forming the displacement with a reinforcing rib extending in a direction opposed to the direction of the displacement.
14. The method as defined in claim 1, and the step of:
- after the forming step, adhering a layer of coating material to the sheet of material across the portion of the periphery of the displacement.
15. The method as defined in claim 14 wherein,
- the adhering step forms a continuous layer of flexible coating material.
16. The method as defined in claim 7 wherein,
- during the forming step, shearing the portion of the periphery of each displacement at least partially through the thickness dimension of the sheet of material.
17. The method as defined in claim 7 wherein,
- during the forming step, plastically deforming the periphery portion of each displacement without shearing through the sheet of material.
18. The method as defined in claim 1 wherein,
- the displacement is a tongue extending from the sheet of material up to the portion of the periphery.
19. The method as defined in claim 1 wherein,
- the displacement is an area longitudinally adjacent to the portion of the periphery.
20. A method of preparing a sheet of material for bending along a bend line comprising the steps of:
- forming a plurality of load-supporting face structures extending longitudinally proximate the bend line;
- forming a plurality of edge structures extending in positions opposed to the face structures; and
- during the forming steps, forming the edge structures and the face structures to define a plurality of bending straps extending obliquely across the bend line.
21. The method as defined in claim 20 wherein,
- the forming steps are accomplished by displacing the sheet of material in a thickness direction to produce the plurality of face structures and opposed edge structures.
22. The method as defined in claim 21 wherein,
- the displacing step is accomplished using one of a stamping process, a punching process, a roll-forming process, a pressing process and an embossing process.
23. The method as defined in claim 20 wherein,
- the forming steps are accomplished by forming the face structures and the opposed edge structures in positions and with configurations producing engagement of the edge structures with the face structures during bending of the sheet of material along the bend line.
24. The method as defined in claim 23 wherein,
- the forming steps are accomplished by forming the face structures and the opposed edge structures to alternate on opposite sides of the bend line in positions having a jog distance across the bend line of between about −0.5 to about +0.5 times the thickness of the sheet material.
25. A method of preparing a sheet of material for bending along a bend line comprising the steps of:
- shearing the sheet of material at least partially through the thickness dimension of the sheet of material along a plurality of shear lines configured and positioned along the bend line to produce edge-to-face engagement of the sheet of material on opposite sides of the shear lines during bending.
26. The method as defined in claim 25 wherein,
- the shearing step is accomplished using one of stamping dies, a knife, punching dies, embossing dies and roll-forming dies.
27. The method as defined in claim 25 wherein,
- the shear lines are one of D-shaped and oval-shaped.
28. The method as defined in claim 25 wherein,
- the shear lines are elongated along the bend line and extend substantially parallel to the bend line in a central portion and have end portions which curve away from the bend line.
29. A method of bending a sheet of material comprising the steps of:
- forming a plurality of displacements in the thickness direction of the sheet of material with a portion of the periphery of each displacement closest to the bend line providing an edge and opposed face configured and positioned to produce edge-to-face engagement of the sheet of material on opposite sides of the portion of the periphery during bending; and
- bending the sheet of material along the bend line.
30. The method as defined in claim 29 wherein,
- the forming step is accomplished by using one of: a stamping process, a roll-forming process, a punching process and an embossing process.
31. The method as defined in claim 29 wherein,
- the forming step shears the portion of the periphery partially through the thickness dimension of the sheet of material; and
- the bending step fractures the portion of the periphery through the remainder of the thickness dimension of the sheet of material.
32. The method as defined in claim 29 wherein,
- the forming step is accomplished by plastically deforming the sheet of material without shearing through the sheet of material; and
- the bending step is accomplished without fracturing the sheet of material.
33. The method as defined in claim 29 wherein,
- during the bending step, the sheet of material is bent in the direction of the displacements.
34. The method as defined in claim 29 wherein,
- during the bending step, the sheet of material is bent in a direction opposed to the direction of the displacements.
35. The method as defined in claim 29 wherein,
- the bending step is accomplished by moving at least one of a die and a tool plate toward each other with the sheet of material mounted therebetween on the tool plate with the bend line superimposed over an edge of the tool plate.
36. The method as defined in claim 29 wherein,
- the bending step is accomplished by moving at least one of a bladder and a tool plate toward each other with the sheet of material mounted therebetween on the tool plate with the bend line superimposed on an edge of the tool plate.
37. The method as defined in claim 29, and the step of:
- after the bending step, securing a shin guard to the sheet material to extend across the bend line.
38. The method as defined in claim 29, and the step of:
- depositing a continuous layer of coating material on at least one surface of the sheet of material across the displacements and the bend line after the bending step.
39. The method as defined in claim 29, and the step of:
- depositing a continuous layer of flexible coating material on at least one surface sheet of material across the displacements and the bend line before the bending step.
40. The method as defined in claim 29 wherein,
- the bending step is accomplished manually.
41. The method as defined in claim 29 wherein,
- the bending step is accomplished using a press brake.
42-65. (canceled)
Type: Application
Filed: Nov 29, 2005
Publication Date: Apr 13, 2006
Applicant: Industrial Origami, LLC (San Francisco, CA)
Inventors: Max Durney (San Francisco, CA), Philip Arnold (Redwood City, CA)
Application Number: 11/290,968
International Classification: B21D 28/26 (20060101);