ROLLER OFFSET FORMING TOOL AND METHOD OF MITIGATING DISTORTION IN A METAL SHEET

Abstract

A roller offset forming tool includes a first roller configured to rotate in a first direction against a metal sheet. The first roller includes a first bead having a first shape. The tool includes a second roller disposed opposite and configured to engage with the first roller. The second roller is configured to rotate in a second direction that is opposite to the first direction against the metal sheet to thereby deform the metal sheet and form an offset feature therein. The second roller includes a secondary bead having a second geometry. The first bead is configured to align and mate with the secondary bead thereby hold the metal sheet between the first and second rollers. The first shape and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature.

Claims

1. A roller offset forming tool comprising: a first roller configured to rotate in a first direction about a first longitudinal axis against a metal sheet; wherein the first roller includes a first bead having a first shape; and a second roller disposed opposite and configured to engage with the first roller; wherein the second roller is configured to rotate in a second direction that is opposite to the first direction about a second longitudinal axis against the metal sheet to thereby deform the metal sheet and form an offset feature therein; wherein the second roller includes a secondary bead having a second geometry; wherein the first bead is configured to align and mate with the secondary bead along a first vertical axis that is substantially perpendicular to the first longitudinal axis and the second longitudinal axis to thereby hold the metal sheet between the first roller and the second roller; wherein the first shape and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature.

2. The roller offset forming tool of claim 1, wherein: the first bead defines a first channel therein; and the secondary bead is configured to protrude into the first channel along the first vertical axis.

3. The roller offset forming tool of claim 1, wherein each of the first bead and the secondary bead is symmetrical across the first vertical axis.

4. The roller offset forming tool of claim 1, wherein the first bead is symmetrical across the first vertical axis and the secondary bead is asymmetrical across the first vertical axis.

5. The roller offset forming tool of claim 1, wherein: the first roller further includes a primary bead spaced apart from the first bead along the first longitudinal axis and having a first geometry; and the second roller further includes a second bead spaced apart from the secondary bead along the second longitudinal axis and having a second shape; wherein the first geometry and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature.

6. The roller offset forming tool of claim 5, wherein the second bead is configured to align and mate with the primary bead along a second vertical axis spaced apart from the first vertical axis along the second longitudinal axis to thereby hold the metal sheet between the first roller and the second roller.

7. The roller offset forming tool of claim 5, wherein: the second bead defines a second channel therein; and the primary bead is configured to protrude into the second channel.

8. The roller offset forming tool of claim 5, wherein: the first bead has a first radius; the primary bead has a primary radius that is less than the first radius; the second bead has a second radius; and the secondary bead has a secondary radius that is less than the second radius.

9. The roller offset forming tool of claim 5, wherein: the first roller has a first distal end; the second roller has a second distal end aligned with the first distal end along a vertical axis that is substantially perpendicular to the first longitudinal axis and the second longitudinal axis; the primary bead is disposed at a first distance from the first distal end; the secondary bead is disposed at a second distance from the second distal end; and the second distance is from 20% of the first distance from the first distal end to 80% of the first distance from the first distal end.

10. A motor vehicle comprising an article formed by the roller offset forming tool of claim 1.

11. A roller offset forming system comprising a metal sheet sandwiched between and disposed in contact with the first bead and the secondary bead of the roller offset forming tool of claim 1.

12. The roller offset forming system of claim 11, wherein the metal sheet is substantially free from distortion in the area spaced apart from the offset feature.

13. A roller offset forming tool comprising: a first roller configured to rotate in a first direction against a metal sheet; wherein the first roller includes a first bead having a first shape and a primary bead spaced apart from the first bead and having a first geometry; and a second roller disposed opposite and configured to engage with the first roller; wherein the second roller is configured to rotate in a second direction that is opposite to the first direction against the metal sheet to thereby deform the metal sheet and form an offset feature therein; wherein the second roller includes a second bead having a second shape and a secondary bead spaced apart from the second bead and having a second geometry; wherein the first shape, the second shape, the first geometry, and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature; wherein each of the first shape and the second geometry incudes a bottom fillet, a top fillet spaced apart from the bottom fillet, a top, a bottom spaced apart from the top, a side wall connecting the top and the bottom, and an angle of inclination defined between the bottom and the side wall; and wherein each of the first shape and the second geometry is defined by at least one of: a first variable set including a bottom fillet radius, a top fillet radius, a bottom half width, a top half width, and a bead height; and a second variable set including the bottom fillet radius, the top fillet radius, the angle of inclination, a side wall length, and the top half width.

14. The roller offset forming tool of claim 13, wherein the first shape is dependent upon the second geometry.

15. The roller offset forming tool of claim 13, wherein the first shape is independent of the second geometry.

16. The roller offset forming tool of claim 13, wherein the angle of inclination is greater than 0 and less than or equal to 90.

17. A method of mitigating a distortion of a workpiece, the method comprising: forming the workpiece having an offset feature and a plurality of areas each spaced apart from the offset feature from a metal sheet with a roller offset forming tool, wherein the roller offset forming tool includes: a first roller configured to rotate in a first direction about a first longitudinal axis against a metal sheet; wherein the first roller includes a first bead having a first shape; and a second roller disposed opposite and configured to engage with the first roller; wherein the second roller is configured to rotate in a second direction that is opposite to the first direction about a second longitudinal axis against the metal sheet to thereby deform the metal sheet and form an offset feature therein; wherein the second roller includes a secondary bead having a second geometry; wherein the first bead is configured to align and mate with the secondary bead along a first vertical axis that is substantially perpendicular to the first longitudinal axis and the second longitudinal axis to thereby hold the metal sheet between the first roller and the second roller; wherein the first shape and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature; measuring a height (h.sub.o) of the offset feature and an actual height (h.sub.i) of each of the plurality of areas; assigning a distortion degree value (DDV) to the workpiece; determining whether the distortion degree value (DDV) is less than or equal to a threshold distortion degree value (DDV.sub.t); if the distortion degree value (DDV) is greater than the threshold distortion degree value (DDV.sub.t), changing at least one of the first shape and the second geometry and forming a subsequent workpiece; and if the distortion degree value (DDV) is less than or equal to the threshold distortion degree value (DDV.sub.t), forming the subsequent workpiece without changing at least one of the first shape and the second geometry to thereby mitigate the distortion of the workpiece.

18. The method of claim 17, wherein assigning includes calculating the distortion degree value according (DDV) to formula (I):
DDV=root mean square(h.sub.ih)(I) wherein: h.sub.i is the actual height of one of the plurality of areas; and h is an ideal height of any distortion and is less than the height (h.sub.o) of the offset feature such that as (h.sub.ih) approaches zero, the distortion of the workpiece is mitigated.

19. The method of claim 17, wherein forming includes sandwiching the metal sheet between the first bead and the secondary bead.

20. The method of claim 19, wherein forming includes turning the first roller in the first direction against the metal sheet and turning the second roller in the second direction against the metal sheet such that the primary bead deforms the metal sheet at the secondary bead and thereby forms the offset feature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a schematic side view of a roller offset forming tool including a first roller spaced apart from a second roller.

[0027] FIG. 2 is a schematic side view of a first bead, a primary bead, a second bead, and a secondary bead of the roller offset forming tool of FIG. 1.

[0028] FIG. 3A is a schematic profile view of a portion of another embodiment of the first roller of FIGS. 1 and 2 as defined by a first variable set.

[0029] FIG. 3B is a schematic profile view of a portion of another embodiment of the second roller of FIGS. 1 and 2 as defined by a second variable set.

[0030] FIG. 4 is a schematic profile view of a portion of the first roller and the second roller of FIGS. 1 and 2.

[0031] FIG. 5 is a schematic side view of a roller offset forming system including the roller offset forming tool of FIGS. 1 and 2.

[0032] FIG. 6 is a schematic top view of a workpiece that includes an offset feature formed by the offset forming tool of FIGS. 1 and 2.

[0033] FIG. 7 is a schematic perspective view of a motor vehicle including an article formed by the roller offset forming tool of FIGS. 1 and 2.

[0034] FIG. 8 is a schematic flow diagram of a method of mitigating a distortion of a workpiece formed by the roller offset forming tool of FIGS. 1 and 2.

[0035] FIG. 9 is a schematic perspective view of the workpiece of FIG. 6.

[0036] FIG. 10 is a schematic side view of the workpiece of FIG. 9.

DETAILED DESCRIPTION

[0037] Referring to the Figures, wherein like reference numerals refer to like elements, a roller offset forming tool 10 (FIGS. 1 and 2) and method 12 (FIG. 8) of mitigating distortion 14 (FIG. 10) in a workpiece 16 (FIG. 9) formed from a metal sheet 18 (FIG. 5) are shown generally. The roller offset forming tool 10 and method 12 may be useful for applications requiring three-dimensional articles 20 (FIG. 7) formed from the metal sheet 18 and including an offset feature 22 (FIG. 6). In particular, the roller offset forming tool 10 and method 12 may be useful for inducing one or more offset features 22 or bends in the metal sheet 18 without creating undesirable distortion 14 in an area 24 (FIGS. 6 and 9) spaced apart from the offset feature 22.

[0038] More specifically, the roller offset forming tool 10 and method 12 form the offset feature 22 using a customized set of rollers 26, 28 (FIG. 1) that include a first bead 42 (FIG. 1) and a secondary bead 32 (FIG. 1) configured for inducing deformation to the metal sheet 18, increasing a stiffness of the metal sheet 18 at the offset feature 22, and controlling distortion 14 at areas 24 apart from the offset feature 22. The set of rollers 26, 28 may be customized with the first bead 42 and secondary bead 32 to avoid additional tool investment and ensure excellent dimensional accuracy of the offset feature 22 and stiffness of the formed workpiece 16. As such, the roller offset forming tool 10 and method 12 may enable production of articles 20 having complex shapes and excellent dimensional accuracy without excess distortion 14.

[0039] Therefore, the roller offset forming tool 10 and method 12 may be useful for automotive applications such as, but not limited to, prototyping and manufacturing articles 20 such as shear plates, skid plates, ducts, brackets, wire tracks, tools, assembly aids, and other vehicle components. For example, a motor vehicle 34 (FIG. 7) may include the article 20, such as a shear plate for a battery, formed by the roller offset forming tool 10 and method 12. Alternatively, the roller offset forming tool 10 and method 12 may be useful for non-automotive applications such as, but not limited to, prototyping and manufacturing articles 20 and components for aerospace, aviation, marine, transportation, robot, architectural, industrial, medical, and consumer product applications.

[0040] Referring now to FIGS. 1 and 2, the roller offset forming tool 10 includes a first roller 26 configured to rotate in a first direction 36 about a first longitudinal axis 62 against the metal sheet 18 (FIG. 5). The roller offset forming tool 10 also includes a second roller 28 disposed opposite the first roller 26 and configured to engage with the first roller 26. The second roller 28 is configured to rotate in a second direction 38 that is opposite to the first direction 36 about a second longitudinal axis 64 against the metal sheet 18 to thereby deform the metal sheet 18 and form the offset feature 22 therein. For example, the first roller 26 and the second roller 28 may be annular and may be configured to hold the metal sheet 18 therebetween during roller offset forming processes. In one non-limiting example, the first roller 26 may be configured as a punch and the second roller 28 may be configured as a die.

[0041] As best shown in FIGS. 1 and 2, the first roller 26 includes the first bead 42 having a first shape 122 (FIG. 1). Similarly, the second roller 26 includes the secondary bead 32 having a secondary geometry 48 (FIG. 1). The first bead 42 is configured to align and mate with the secondary bead 32 along a first vertical axis 80 (FIG. 2) that is substantially perpendicular to the first longitudinal axis 62 and the second longitudinal axis 64 to thereby hold the metal sheet 18 between the first roller 26 and the second roller 28.

[0042] In another embodiment described with continued reference to FIG. 2, the first roller 26 may also include a primary bead 30 spaced apart from the first bead 42 along the first longitudinal axis 62 and having a first geometry 44. To be clear, the first bead 42 and the primary bead 30 may not necessarily have the same shape or form. That is, the first bead 42 and the primary bead 30 may have different shapes. The first shape 122 (FIG. 1) is used herein to describe the first bead 42, and the first geometry 44 (FIG. 1) is used herein to describe the primary bead 30. Similarly, the second roller 28 may also include a second bead 46 spaced apart from the secondary bead 32 and having a second shape 124 (FIG. 1). To be clear, the second bead 46 and the secondary bead 32 may not necessarily have the same shape or form. That is, the second bead 46 and the secondary bead 32 may have different shapes. The second shape 124 is used herein to describe the second bead 46, and the second geometry 48 is used herein to describe the secondary bead 32.

[0043] As set forth in more detail below, the first shape 122 and the second geometry 48 are configured to mitigate the distortion 14 of the metal sheet 18 in the area 24 (FIGS. 6 and 9) apart from the offset feature 22 (FIG. 6) and stiffen the metal sheet 18 at the offset feature 22. Further, for embodiments including two sets of beads, i.e., the first bead 42, the secondary bead 32, the second bead 46, and the primary bead 30, the first geometry 44 and the second geometry 48 and the first shape 122 and the second shape 124 may be configured to mitigate the distortion 14 of the metal sheet 18 in the area 24 apart from the offset feature 22 and stiffen the metal sheet 18 at the offset feature 22. In particular, referring to FIG. 1, the offset feature 22 itself may be formed due to an inclination offset of the first roller 26 and the second roller 28, e.g., at a sloped or inclined surface 126 (FIG. 1) between the first bead 42 and the primary bead 30 that is paired with a corresponding sloped or inclined surface 226 (FIG. 1) between the second bead 46 and the secondary bead 32. However, the first shape 122 and the second geometry 48 may control and/or minimize the distortion 14 in the area 24 apart from the offset feature 22. More specifically, the first shape 122 and the second geometry 48 may form satellite features that surround the offset feature 22 and minimize distortion apart from the offset feature 22. That is, for embodiments including two pairs of beads 42-32, 46-30, based on the first geometry 44 of the primary bead 30 and the second geometry 48 of the secondary bead 32, in combination with the respective first and second shapes 122, 124 of the first and second beads 42, 46, the metal sheet 18 may be substantially free from distortion 14 in the area 24 spaced apart from the offset feature 22.

[0044] As described with continued reference to FIG. 2, each of the first bead 42, the primary bead 30, the second bead 46, and the secondary bead 32 may be annular and may either protrude in a radial direction from or be recessed toward respective centers of the first roller 26 and the second roller 28. The primary bead 30 may be relatively smaller than the first bead 42 and the secondary bead 32 may be relatively smaller than the second bead 46. That is, the first bead 42 may have a first radius 50 and the primary bead 30 may have a primary radius 52 that is less than the first radius 50. Similarly, the second bead 46 may have a second radius 54 and the secondary bead 32 may have a secondary radius 56 that is less than the second radius 54. The first bead 42, the primary bead 30, the second bead 46, and the secondary bead 32 may be referred to as mini beads because the beads 42, 30, 46, 32 may be small as compared to an overall dimension of the respective first and second rollers 26, 28. That is, a step size or height of protrusion of the primary bead 30 and the secondary bead 32 and a step size or depth of recession of the first bead 42 and second bead 46 may be comparatively smaller than an overall dimension of the first and second rollers 26, 28, respectively. The mini beads 42, 30, 46, 32 may be shaped to induce additional deformation to the metal sheet 18, form the offset feature 22, stiffen the metal sheet 18 at the offset feature 22, and mitigate the distortion 14 of the metal sheet 18 in the area 24 apart from the offset feature 22.

[0045] In particular, and as described with continued reference to FIG. 2, during roller offset forming operations, the first bead 42 may be configured to align with the secondary bead 32 and the second bead 46 may be configured to align with the primary bead 30 to thereby hold the metal sheet 18 between the first roller 26 and the second roller 28. The first bead 42 may define a first channel 58 or concavity or depression therein and the second bead 46 may define a second channel 60 or concavity or depression therein. That is, the first shape 122 may be the first channel 58 and the second shape 124 may be the second channel 60. The primary bead 30 may be configured to protrude into the second channel 60 and the secondary bead 32 may be configured to protrude into the first channel 58. As such, the first roller 26 and the second roller 28 may mate at the first bead 42secondary bead 32 pairing and at the second bead 46primary bead 30 pairing to thereby hold the metal sheet 18 therebetween. As the first roller 26 turns in the first direction 36 (FIG. 1) and the second roller 28 turns in the second direction 38 (FIG. 1) that is opposite to the first direction 36, the roller offset forming tool 10 may form the offset feature 22 in the metal sheet 18.

[0046] In greater detail and referring again to FIG. 2, the first roller 26 may have the first longitudinal axis 62 and the primary bead 30 may be spaced apart from the first roller 26 along the first longitudinal axis 62. In addition, the second roller 28 may have the second longitudinal axis 64 and the secondary bead 32 may be spaced apart from the second bead 46 along the second longitudinal axis 64. That is, the first roller 26 may have a first distal end 66 and the second roller 28 may have a second distal end 68 aligned with the first distal end 66 along a vertical axis 70 that is substantially perpendicular to the first longitudinal axis 62 and the second longitudinal axis 64. The primary bead 30 may be disposed at a first distance 72 from the first distal end 66 and the secondary bead 32 may be disposed at a second distance 74 from the second distal end 68. The second distance 74 may be from 20% of the first distance 72 to 80% of the first distance 72, e.g., from 25% of the first distance 72 to 75% of the first distance 72, or from 50% of the first distance 72 to 65% of the first distance 72.

[0047] Further, as described with reference to FIG. 2, the first bead 42 may have a first face width 76 along the first longitudinal axis 62 and the secondary bead 32 may be positioned along the second longitudinal axis 64 so as to align with the first bead 42 within the dimension of the first face width 76. Similarly, the second bead 46 may have a second face width 78 along the second longitudinal axis 64 and the primary bead 30 may be positioned along the first longitudinal axis 62 so as to align with the second bead 46 within the dimension of the second face width 78. Therefore, acceptable positioning of the primary bead 30 and the secondary bead 32 may be selected and optimized within the constraints of the second face width 78 and first face width 76, respectively.

[0048] With continued reference to FIG. 2, the first bead 42 and the secondary bead 32 may align and mate along the first vertical axis 80 that is substantially perpendicular to the first longitudinal axis 62 and the second longitudinal axis 64. Likewise, the second bead 46 may be configured to align and mate with the primary bead 30 along a second vertical axis 82 spaced apart from the first vertical axis 80 along the second longitudinal axis 64 to thereby hold the metal sheet 18 between the first roller 26 and the second roller 28. That is, the primary bead 30 and the second bead 46 may align and mate along the second vertical axis 82 spaced apart from the first vertical axis 80 along the second longitudinal axis 64.

[0049] Referring now to FIG. 5, in one non-limiting example, each of the first bead 42 and the secondary bead 32 may be symmetrical across the first vertical axis 80. That is, the first shape 122 of the first bead 42 may match the second geometry 48 of the secondary bead 32. Additionally or alternatively, each of the second bead 46 and the primary bead 30 may be symmetrical across the second vertical axis 82. That is, the second shape 124 of the second bead 46 may match the first geometry 44 of the primary bead 30.

[0050] However, referring to FIG. 4, in another non-limiting example, the first bead 42 may be symmetrical across the first vertical axis 80 and the secondary bead 32 may be asymmetrical across the first vertical axis 80. That is, the first shape 122 of the first bead 42 may not match the second geometry 48 of the secondary bead 32. Additionally or alternatively, although not shown, the second bead 46 may be symmetrical across the second vertical axis 82 and the primary bead 30 may be asymmetrical across the second vertical axis 82. That is, the second shape 124 of the second bead 46 may not match the first geometry 44 of the primary bead 30.

[0051] Referring now to FIGS. 3A and 3B, in another embodiment, each of the first shape 122 and the second geometry 48 includes a bottom fillet 84, a top fillet 86 spaced apart from the bottom fillet 84, a top 88, a bottom 90 spaced apart from the top 88, a side wall 92 connecting the top 88 and the bottom 90, and an angle of inclination 94 defined between the bottom 90 and the side wall 92. The angle of inclination 94 may be greater than 0 and less than or equal to 90 so that the offset feature 22 may have a gradual transition between the bottom 90 and the side wall 92.

[0052] For this embodiment, each of the first shape 122 and the second geometry 48 is defined by at least one of a first variable set 96 (FIG. 3A) and a second variable set 98 (FIG. 3B). The first variable set 96 includes a bottom fillet radius 100, a top fillet radius 102, a bottom half width 104, a top half width 106, and a bead height 108. The second variable set 98 includes the bottom fillet radius 100, the top fillet radius 102, the angle of inclination 94, a side wall height length 110, and the top half width 106.

[0053] The first variable set 96 and/or the second variable set 98 may be iteratively optimized, for example, based on a feedback loop of Gaussian Process Regression and Bayesian Optimization and finite element analysis to thereby provide the first shape 122 of the first bead 42 and the second geometry 48 of the secondary bead 32. Further, design criteria and parameters based on the first variable set 96 may be correlated with and converted to design criteria and parameters based on the second variable set 98.

[0054] For example, using the first variable set 96 or the second variable set 98 of five independent variables, each side of the first bead 42 across the first vertical axis 80 and each side of the secondary bead 32 across the first vertical axis 80 may be parameterized to define the respective first shape 122 and second geometry 48 of the beads 42, 32. Symmetric design of the two sides of the first bead 42 and the two sides of the secondary bead 32 may not be required. However, for an asymmetric design, both sides of the first bead 42 and/or secondary bead 32 may be defined by the first variable set 96 and/or the second variable set 98. In addition, each side of the second bead 46 across the second vertical axis 82 and each side of the primary bead 30 across the second vertical axis 82 may be parameterized to define the respective second shape 124 and first geometry 44 of the beads 46, 30. Symmetric design of the two sides of the second bead 46 and the two sides of the primary bead 30 may not be required. However, for an asymmetric design, both sides of the second bead 46 and/or primary bead 30 may be defined by the first variable set 96 and/or the second variable set 98.

[0055] Further, the first shape 122 of the first bead 42 and the second geometry 48 of the secondary bead 32 may be identified independently or dependently. That is, the first shape 122 of the first bead 42 may be dependent on the second geometry 48 of the secondary bead 32. Alternatively, the first shape 122 of the first bead 42 may be independent of the second geometry 48 of the secondary bead 32. Similarly, the second shape 124 of the second bead 46 and the first geometry 44 of the primary bead 30 may be identified independently or dependently. That is, the second shape 124 of the second bead 46 may be dependent on the first geometry 44 of the primary bead 30. Alternatively, the second shape 124 of the second bead 46 may be independent of the first geometry 44 of the primary bead 30. Likewise, the first shape 122 of the first bead 42 and the second shape 124 of the second bead 46 may be identified independently or dependently. That is, the first shape 122 of the first bead 42 may be dependent on the second shape 124 of the second bead 46. Alternatively, the first shape 122 of the first bead 42 may be independent of the second shape 124 of the second bead 46. In like manner, the first geometry 44 of the primary bead 30 and the second geometry 48 of the secondary bead 32 may be identified independently or dependently. That is, the first geometry 44 of the primary bead 30 may be dependent on the second geometry 48 of the secondary bead 32. Alternatively, the first geometry 44 of the primary bead 30 may be independent of the second geometry 48 of the secondary bead 32.

[0056] In one non-limiting example best shown in FIGS. 3A and 3B, the first shape 122 may be dependent on the second geometry 48. That is, a design of the first shape 122 may depend on a design of the second geometry 48. In another non-limiting example best shown in FIG. 4, the first shape 122 may be independent of the second geometry 48. That is, the design of the first shape 122 and the second geometry 48 may not depend on one another.

[0057] The first and second shapes 122, 124 and the first and second geometries 44, 48 may also be constrained by other considerations such as manufacturing feasibility of the first roller 26 and associated beads 30, 42 and second roller 28 and associated beads 32, 46. For example, referring to FIGS. 3A and 3B, for some applications, the bottom fillet radius 100 and the top fillet radius 102 may be constrained by a minimum value. Similarly, the bottom half width 104 may be greater than or equal to the top half width 106.

[0058] In addition, although the roller offset forming tool 10 is described herein as including at least one bead pair, i.e., the first bead 42 and the secondary bead 32, or in some embodiments, at least two bead pairs, i.e., additionally the primary bead 30 and the second bead 46, the roller offset forming tool 10 may include more than four beads or two pairs of beads according to desired characteristics and location of the offset feature 22. For example, although not shown, the first roller 26 may include a third bead and a tertiary bead spaced apart from the third bead. Likewise, as a non-limiting example, the second roller 28 may include a fourth bead and a quaternary bead spaced apart from the fourth bead. The third bead may be configured to align with the quaternary bead and the fourth bead may be configured to align with the tertiary bead.

[0059] Advantageously, the roller offset forming tool 10 optimizes a stiffness of the workpiece 16 while mitigating the distortion 14 of the workpiece 16 at areas 24 apart from the offset feature 22 by allowing for optimized first and second rollers 26, 28 that include one or more mini-beads, e.g., the first bead 42 and the secondary bead 32, disposed at calculated positions according to the desired offset feature 22 and desired stiffness of the workpiece 16.

[0060] Referring now to FIG. 5, a roller offset forming system 40 may include the metal sheet 18 sandwiched between and disposed in contact with the first bead 42 and the secondary bead 32 of the roller offset forming tool 10. Likewise, the roller offset forming system 40 may also include the metal sheet 18 sandwiched between and disposed in contact with the primary bead 30 and the second bead 46 of the roller offset forming tool 10. The metal sheet 18 may be formed from any suitable metal according to an application or end use of the workpiece 16. In one non-limiting example, the metal sheet 18 may be formed from an aluminum alloy such as AA5754-O and may be from 1 mm to 1.5 mm thick.

[0061] Referring now to FIG. 8, the method 12 of mitigating the distortion 14 of the workpiece 16 includes forming 112 the workpiece 16 having the offset feature 22 and a plurality of areas 24 (FIG. 9) each spaced apart from the offset feature 22 from the metal sheet 18 with the roller offset forming tool 10. That is, forming 112 may include sandwiching the metal sheet 18 between at least the first bead 42 and the secondary bead 32, and in some embodiments, additionally between the second bead 46 and the primary bead 30 as set forth above. Further, forming 112 may include turning the first roller 26 in the first direction 36 against the metal sheet 18 and turning the second roller 28 in the second direction 38 against the metal sheet 18 such that the first bead 42 deforms the metal sheet 18 at the secondary bead 32 and thereby forms the offset feature 22.

[0062] Although the offset feature 22 is shown as generally rectangular or stadium-shaped in FIGS. 9 and 10, the offset feature 22 may have any desired shape according to the selected first shape 122 and second geometry 48, or in addition, the first geometry 44 and second shape 124. That is, a depth, width, and other geometric characteristics of the offset feature 22 can be altered by adjusting a relative position of the first and second rollers 26, 28 and by changing the first shape 122 and second geometry 48 of the first bead 32 and secondary bead 32, respectively, and the second shape 124 of the second bead 46 and the first geometry 44 of the primary bead 30. Each of plurality of areas 24 may be spaced apart from the offset feature 22 and may be located, by way of non-limiting examples, in one or more of a corner of the metal sheet 18, at an edge of the metal sheet 18, in a center region of the metal sheet 18, and in an off-center region of the metal sheet 18.

[0063] Referring again to FIG. 8 and as best described with reference to FIGS. 9 and 10, the method 12 also includes measuring 114 a height (h.sub.o) of the offset feature 22 and an actual height (h.sub.i) of each of the plurality of areas 24. The method 12 further includes assigning 116 a distortion degree value (DDV) to the workpiece 16. For example, assigning 116 may include calculating the distortion degree value (DDV) according to formula (I):

DDV=root mean square(h.sub.ih)(I) [0064] wherein h.sub.i is the actual height of one of the plurality of areas 24, and h is an ideal height of any distortion 14 and is less than the height (h.sub.o) of the offset feature 22 such that as (h.sub.ih) approaches zero, the distortion 14 of the workpiece 16 is mitigated. For example, h may correspond to a tolerance for distortion 14 in the workpiece 16 formed from the metal sheet 18, such as from 0 mm to 5 mm or from 0.5 mm to 3 mm or from 1 mm to 2 mm.

[0065] The method 12 also includes determining 118 whether the distortion degree value (DDV) is less than or equal to a threshold distortion degree value (DDV.sub.t). The threshold distortion degree value (DDV.sub.t) may be set according to a tolerance for distortion 14 in the workpiece 16 and may be dependent upon an end use of the workpiece 16 or article 20.

[0066] Referring again to FIG. 8, if the distortion degree value (DDV) is greater than the threshold distortion degree value (DDV.sub.t), the method 12 includes changing 120 at least one of the first shape 122 and the second geometry 48 and forming 112 a subsequent workpiece 16. That is, the method 12 may include selecting at least one of a new first shape 122 and second geometry 48 before forming another workpiece 16. If the distortion degree value (DDV) is less than or equal to the threshold distortion degree value (DDV.sub.t), the method 12 includes forming 112 the subsequent workpiece 16 without changing 120 at least one of the first shape 122 and the second geometry 48 to thereby mitigate the distortion 14 of the workpiece 16. That is, if the distortion degree value (DDV) is less than or equal to the threshold distortion degree value (DDV.sub.t), the first shape 122 and/or the second geometry 48 is optimized to produce the offset feature 22 such that distortion 14 in areas 24 apart from the offset feature 22 is mitigated.

[0067] Advantageously, the method 12 allows for quantification of distortion 14 and incremental design changes to the first shape 122 of the first bead 42 and the second geometry 48 of the secondary bead 32, and in some embodiments, additionally the first geometry 44 of the primary bead 30 and the second shape 124 of the second bead 46. That is, the method 12 uses at least a parameterized first shape 122 and a parameterized second geometry 48 to achieve a resulting reduction in distortion 14 in the metal sheet 18.

[0068] As such, the method 12 and roller offset forming tool 10 may be capable of producing smoothly curved panels from flat meal sheets 18 with high dimensional accuracy. The roller offset forming tool 10 and method 12 may be useful for forming the offset feature 22 using the set of rollers 26, 28 (FIG. 1) that include the first bead 42 (FIG. 1) and the secondary bead 32 (FIG. 1) for inducing deformation to the metal sheet 18, increasing a stiffness of the metal sheet 18 at the offset feature 22, and controlling distortion 14 at areas 24 apart from the offset feature 22, all without additional tool investment. Therefore, the roller offset forming tool 10 and method 12 may enable production of articles 20 having complex shapes and excellent dimensional accuracy without excess distortion 14.

[0069] The described embodiments of the present disclosure are intended to serve as non-limiting examples, and other embodiments may take various and alternative forms. In addition, the appended drawings are not necessarily to scale, and may present a somewhat simplified representation of various features of the present disclosure, including, for example, specific dimensions, orientations, locations, and shapes. Details associated with such features will be determined in part by the intended application and use environment of the described embodiments.

[0070] For purposes of the present description, unless specifically disclaimed, use of the singular includes the plural and vice versa, the terms and and or shall be both conjunctive and disjunctive, and the words including, containing, comprising, having, and the like shall mean including without limitation. Moreover, words of approximation such as about, substantially, generally, approximately, etc., may be used herein in the sense of at, near, or nearly at, or within 0-5% of, or within acceptable manufacturing tolerances, or logical combinations thereof. As used herein, a component that is configured to perform a specified function is capable of performing the specified function without alteration, rather than merely having potential to perform the specified function after further modification. In other words, the described hardware, when expressly configured to perform the specified function, is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the specified function. In addition, the use of ordinals such as first, second and third does not necessarily imply a ranked sense of order, but rather may only distinguish between multiple instances of an act or structure.

[0071] The detailed description and the drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is defined solely by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments exist for practicing the present teachings defined in the appended claims. Moreover, this disclosure expressly includes combinations and sub-combinations of the elements and features presented above and below.