EP3421147B1

EP3421147B1 - Roll forming system for forming a variable thickness blank and method for forming a variable thickness blank

Info

Publication number: EP3421147B1
Application number: EP18174346.9A
Authority: EP
Inventors: Stephan RÖHNER; Ranga Reddy Suhant Prajwal
Original assignee: Dus Operating Inc
Current assignee: Dus Operating Inc
Priority date: 2017-06-30
Filing date: 2018-05-25
Publication date: 2022-07-27
Anticipated expiration: 2038-05-25
Also published as: US20190001382A1; CN109201733A; EP3421147A1

Description

The present disclosure relates generally to a roll forming system for forming a variable thickness blank according to the preamble of claim 1 and to a method for forming a variable thickness blank according to the preamble of claim 1 3 (see e.g. US 2013/0020835 A1 ).

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Known roll forming processes provide for altering a thickness of a metal blank in a longitudinal direction parallel to a feed direction of a metal sheet, and for constructing metal blanks from multiple plates of differing thicknesses as desired. Known roll forming processes may not provide for incrementally varying a thickness of a plate across a transverse direction of the plate, and therefore require a second or subsequent manufacturing, welding, or brazing steps to add further material of a differing thickness. Roll forming processes in which metal sheets with a varying thickness of a plate across a transverse direction of the plate are known from documents US 2013/0020835 A1 , US 1,915,084 , US 4,578,979 , DE 10 2006 024 775 A1 and GB 10,850 .
Thus, while current roll forming processes achieve their intended purpose, there is a need for a new and improved system and method for preparing roll formed blanks.

SUMMARY

According to the invention a variable thickness roll forming system comprising the features of claim 1 is provided.
In another aspect of the present disclosure, the multiple shaping faces of the second roller include a first shaping face which defines a first spacing distance between the first shaping face and the face of the first roller.
In another aspect of the present disclosure, the first spacing distance is equal to an initial thickness of the metal sheet.
In another aspect of the present disclosure, the second roller further includes a second shaping face defining a second spacing distance between the second shaping face and the face of the first roller which is less than the initial thickness of the metal sheet.
In another aspect of the present disclosure, the second roller further includes a third shaping face defining a third spacing distance between the third shaping face and the face of the first roller which is less than the initial thickness of the metal sheet.
In another aspect of the present disclosure, the second spacing distance defines a thickness of the second portion of the roll formed blank.
In another aspect of the present disclosure, the third spacing distance defines a thickness of a third portion of the roll formed blank oppositely positioned about the first portion with respect to the second portion.
In another aspect of the present disclosure, the thickness of the second portion is reduced by up to approximately 40% of the thickness of the first portion.
In another aspect of the present disclosure, a first translational roller is positioned between a first roller set of the multiple roller sets and a second roller set of the multiple roller sets.
In another aspect of the present disclosure, the first translational roller when displaced toward the metal sheet in a displacement direction substantially transverse to the metal sheet deforms and thereby laterally lengthens a portion of the metal sheet between the first roller set and the second roller set.
In another aspect of the present disclosure, a second translational roller is positioned between the first roller set and the second roller set and positioned oppositely about the metal sheet with respect to the first translational roller, the second translational roller when displaced toward the metal sheet in a direction opposite to the displacement direction of the first translational roller deforming and thereby lengthening a further portion of the metal sheet.
According to several aspects, a variable thickness roll forming system for forming a variable thickness blank includes multiple sets of cylindrical shaped rollers. Each of the multiple sets of rollers includes: a first roller having a face which is linear where the first roller contacts a metal sheet; and a second roller having multiple shaping faces positioned about a perimeter and directed toward the face of the first roller. Each of the sets of rollers incrementally alters a thickness of the metal sheet in a direction transverse to a feed direction of the metal sheet when the metal sheet is passed between the first roller and the second roller. The metal sheet when passed between the first roller and the second roller forms a roll formed blank having a central portion, a first outer portion and a second outer portion located opposite about the central portion with respect to the first outer portion, the central portion having a thickness greater than a thickness of each of the first outer portion and the second outer portion.
In another aspect of the present disclosure, the thickness of the central portion after passing through a final one of the sets of rollers is substantially equal to an initial thickness of the metal sheet.
In another aspect of the present disclosure, the thickness of each of the first outer portion and the second outer portion is substantially equal after passing through the final one of the sets of rollers.
In another aspect of the present disclosure, the thickness of the first outer portion is greater than the thickness of the second outer portion after passing through the final one of the sets of rollers.
In another aspect of the present disclosure, the thickness of the first outer portion is less than the thickness of the second outer portion after passing through the final one of the sets of rollers.
In another aspect of the present disclosure, the thickness of the first outer portion and the thickness of the second outer portion are reduced by up to approximately 40% of the thickness of the central portion after passing through a final one of the sets of rollers
In another aspect of the present disclosure, a first translational roller is positioned between a first roller set of the sets of cylindrical shaped rollers and a second roller set of the sets of cylindrical shaped rollers, the first translational roller altering a length and a thickness of the metal sheet in a direction parallel to the feed direction of the metal sheet when the first translational roller is pressed into contact with the metal sheet between the first roller set and the second roller set.
In another aspect of the present disclosure, a second translational roller is positioned between the first roller set of the sets of cylindrical shaped rollers and the second roller set of the sets of cylindrical shaped rollers and oppositely about the metal sheet with respect to the first translational roller.
According to the invention a method for forming a variable thickness blank comprising the features of claim 13 is provided.
In another aspect of the present disclosure, the method includes: setting a first spacing distance between a first shaping face of the multiple shaping faces of the second roller and the face of the first roller substantially equal to an initial thickness of the metal sheet; setting a second spacing distance between a second shaping face of the multiple shaping faces of the second roller and the face of the first roller less than an initial thickness of the metal sheet; and setting a third spacing distance between a third shaping face of the multiple shaping faces of the second roller and the face of the first roller less than the initial thickness of the metal sheet.
In another aspect of the present disclosure, the method includes positioning the first, second and third shaping faces wherein the metal sheet when passed between the first roller and the second roller forms a roll formed blank having a central portion, a first outer portion and a second outer portion located opposite about the central portion with respect to the first outer portion, the central portion having a thickness greater than a thickness of the first outer portion and the second outer portion.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1: is a top perspective view of a variable thickness roll forming system for forming a variable thickness blank according to an exemplary embodiment;
FIG. 2: is a cross sectional end elevational view taken at section 2 of FIG. 1;
FIG. 3: is a cross sectional end elevational view taken at section 3 of FIG. 1;;
FIG. 4: is a top perspective view of a multiple roller set gang according to another aspect of the present disclosure;
FIG. 5: is a front elevational view of a single translational roller subsystem providing a longitudinal thickness variation;
FIG. 6: is a front elevational view of a dual translational roller subsystem providing a longitudinal thickness variation;
FIG. 7: is a front perspective view of multiple exemplary components constructed using the variable thickness roll forming system for forming a variable thickness blank of the present disclosure;
FIG. 8: is a top plan view of a metal sheet in an initial state prior to formation using the variable thickness roll forming system of the present disclosure;
FIG. 9: is a cross sectional end elevational view taken at section 9 of FIG. 8;
FIG. 10: is a top plan view of the metal sheet following tailor roll forming operations;
FIG. 11: is a cross sectional end elevational view taken at section 11 of FIG. 10;
FIG. 12: is a top plan view of the metal sheet following tailor roll forming operations;
FIG. 13: is a cross sectional end elevational view taken at section 13 of FIG. 12;
FIG. 14: is a top plan view of the metal sheet following formation of an interim or final part;
FIG. 15: is a cross sectional end elevational view taken at section 15 of FIG. 14;
FIG. 16: is a graph depicting zones defining exemplary strain amounts in different areas of an exemplary roll formed blank of the present disclosure; and
FIG. 17: is a forming limit diagram for the exemplary roll formed blank of FIG. 16.

DETAILED DESCRIPTION

Referring to FIG. 1, a variable thickness roll forming system 10 feeds a metal sheet 12 made for example from a steel or aluminum material off of a reel through multiple sets of generally cylindrical shaped rollers, each incrementally altering a thickness of the metal sheet 12 in at least one of a longitudinal and a transverse direction. According to several aspects the metal sheet 12 is fed into a first roller set 14 and at least a second roller set 16 in a feed direction 18. Initially, in its un-formed condition, the metal sheet 12 as it comes off from a roll or reel of material provides a planar body 20 having a uniform initial thickness 22, for example a thickness of approximately 2.00 mm. The initial thickness 22 can vary depending on the desired final geometry after completion of the roll forming operations.
Each of the roller sets incrementally changes a thickness in at least a transverse direction 24 of the metal sheet 12. In the example shown using the first roller set 14 and the second roller set 16, a roll formed blank 25 of the metal sheet 12 after passing through both the first roller set 14 and the second roller set 16 may include a central portion 26, a first outer portion 28, and a second outer portion 30 located opposite about the central portion 26 with respect to the first outer portion 28. According to several aspects, the central portion 26 may have a first finished thickness 32 which may equal the initial thickness 22. The first outer portion 28 may have a second finished thickness 34 less than or equal to the first finished thickness 32. The second outer portion 30 may have a third finished thickness 36 less than or equal to the first finished thickness 32 and equal to or different from the second finished thickness 34. Other variations in thickness of the central portion 26, the first outer portion 28, and the second outer portion 30 can also be provided, and roll formed blanks 25 may also have only two of the thickness portions, or may have more than three thickness portions.
Referring to FIG. 2 and again to FIG. 1, the first roller set 14 includes a first roller 38 and a second roller 40. The first roller 38 includes a face 42 which according to several aspects is generally linear where the first roller 38 contacts the metal sheet 12. The second roller 40 includes multiple shaping faces about a perimeter directed toward the face 42, including a first shaping face 44 which defines a first spacing distance 46 between the first shaping face 44 and the face 42. According to several aspects, the first spacing distance 46 is equal to the initial thickness 22 of the metal sheet 12. The second roller 40 further includes a second shaping face 48 defining a second spacing distance 50 which is less than the initial thickness 22. The second roller 40 also includes a third shaping face 52 defining a third spacing distance 54 which is less than the initial thickness 22.
Using an exemplary initial thickness 22 of the planar body 20 of the metal sheet 12 of 2.00 mm, according to several aspects, the second spacing distance 50 and the third spacing distance 54 may be equal, and in a non-limiting example may be 1.98 mm. These spacing distances create an initial thickness reduction of 0.02 mm where the metal sheet 12 passes between the face 42 of the first roller 38 and each of the second shaping face 48 and the third shaping face 52. The initial thickness 22 may be unchanged or may have a thickness reduction less than 0.02 mm where the metal sheet 12 passes between the face 42 of the first roller 38 and the first shaping face 44 of the second roller 40.
Referring to FIG. 3 and again to FIG. 2, although each of the roller sets including the second roller set 16 include a first roller and a second roller, for clarifying a distinction between the first roller set 14 and the second roller set 16, the first and second rollers of the second roller set 16 are defined as a third roller 56 and a fourth roller 58. The third roller 56, similar to the first roller 38, includes a face 60 which according to several aspects is generally linear across a width of the third roller 56 where the third roller 56 contacts the metal sheet 12. The fourth roller 58, similar to the second roller 40, provides multiple shaping faces directed toward the face 60, including a fourth shaping face 62 which defines a fourth spacing distance 64 between the fourth shaping face 62 and the face 60 of the third roller 56. According to several aspects, the fourth spacing distance 64 is substantially equal to the initial thickness 22. The fourth roller 58 further includes a fifth shaping face 66 defining a fifth spacing distance 68 which for example is reduced by 0.02 mm from and is thereby less than the second spacing distance 50. The fourth roller 58 also includes a sixth shaping face 70 defining a sixth spacing distance 72 which is reduced by 0.02 mm from and is thereby less than the third spacing distance 54.
Given the exemplary initial thickness 22 of the planar body 20 of the metal sheet 12 of 2.00 mm, according to several aspects, the fifth spacing distance 68 and the sixth spacing distance 72 may be equal, and in a non-limiting example may be 1.96 mm. After the metal sheet 12 passes through the first roller set 14, the spacing distances of the second roller set 16 create an additional thickness reduction of 0.02 mm where the metal sheet 12 passes between the face 60 of the third roller 56 and each of the fifth shaping face 66 and the sixth shaping face 70. The initial thickness 22 may continue to be unchanged where the metal sheet 12 passes between the face 60 of the third roller 56 and the fourth shaping face 62 of the fourth roller 58.
It should be apparent that additional incremental thickness reductions can be made by passing the metal sheet 12 through additional roller sets, as will be discussed in greater detail in reference to FIG. 4. Each roller set of the present disclosure is used to create an additional, incremental thickness reduction in the metal sheet 12, at predetermined positions and by predetermined spacings between the shaping faces of the roller sets.
Referring to FIG. 4 and again to FIGS. 1 through 3, in one exemplary embodiment multiple roller sets are ganged defining a roller set gang 74 having eleven roller sets, including the first roller set 14 and the second roller set 16. An initializing roller set 76 which does not perform thickness reduction may be used as an initial feed roller set, aligning the metal sheet 12 with the remaining roller sets. In the example shown, after the metal sheet 12 passes through the first roller set 14 the central portion 26 of the metal sheet 12 provides the first finished thickness 32 which is equal to the initial thickness 22, the first outer portion 28 has as the second finished thickness 34 a thickness of 1.98 mm, and the second outer portion 30 has as the third finished thickness 36 a thickness of 1.98 mm.
In an exemplary aspect, each of the successive roller sets of the roller set gang 74 incrementally reduces the second finished thickness 34 and the third finished thickness 36 by an additional 0.02 mm. After passing through the initializing roller set 76, each of the successive ten thickness reducing roller sets of the roller set gang 74 reduces a thickness in at least one portion of the metal sheet 12 by 0.02 mm, thereby providing a total thickness reduction of 0.2 mm (10 roller sets each creating a reduction of 0.02 mm). In this example, after passing through an eleventh and final roller set 78 the central portion 26 of the metal sheet 12 retains the first finished thickness 32 which is equal to the initial thickness 22, the first outer portion 28 has as the second finished thickness 34 a final thickness of 1.8 mm, and the second outer portion 30 has as the third finished thickness 36 a final thickness of 1.8 mm.
In the above examples, the initial thickness of 2.00 mm and the thickness reduction of 0.02 mm at each passage between a roller set are exemplary values. The thickness reduction that is desired can be varied depending on the number of roller sets, the initial thickness 22, the material of the metal sheet 12, a desired feed rate of the metal sheet 12, the total thickness reduction desired, and other factors.
Referring to FIG. 5 and again to FIGS. 1 and 4, for producing a longitudinal change in a thickness of the metal sheet 12, several different subsystems can be adopted. According to a first subsystem, a single translational roller 80 is positioned between an axially fixed first roller set 82 and an axially fixed second roller set 84 defining a single offset roller system 86. According to further aspects the single translational roller 80 can be positioned between the first roller set 14 and the second roller set 16, or between any two successive roller sets of the roller set gang 74. The fixed first roller set 82 includes a first roller 88 and a second roller 90 spaced from the first roller 88 to frictionally grip the metal sheet 12. The fixed second roller set 84 includes a third roller 92 and a fourth roller 94 spaced from the third roller 92 to also frictionally grip the metal sheet 12. As the metal sheet 12 is displaced in a feed direction 96 a center-to-center spacing 98 is retained between the fixed first roller set 82 and the second roller set 84.
By displacing the translational roller 80 toward the metal sheet 12 in a displacement direction 100, contact with the metal sheet 12 and further controlled downward displacement of the translational roller 80 deforms and thereby longitudinally stretches a length 102 of the metal sheet 12 between the fixed first roller set 82 and the second roller set 84. A rotational speed of the rollers of the fixed second roller set 84 can also be varied (e.g., increased) from a rotational speed of the rollers of the fixed first roller set 82 to permit longitudinal stretching of the length 102 between the fixed first roller set 82 and the fixed second roller set 84.
Referring to FIG. 6 and again to FIG. 5, according to a second subsystem, a dual offset roller system 104 may be used in place of the single offset roller system 86. The dual off-set roller system 104 includes a first translational roller 106 and an oppositely displaced second translational roller 108 both positioned between an axially fixed first roller set 110 and an axially fixed second roller set 112. The fixed first roller set 110 includes a first roller 114 and a second roller 116 spaced from the first roller 114 to frictionally grip the metal sheet 12. The fixed second roller set 112 includes a third roller 118 and a fourth roller 120 spaced from the third roller 118 to also frictionally grip the metal sheet 12. As the metal sheet 12 is displaced in a feed direction 122 a center-to-center spacing 124 is retained between the first roller set 110 and the second roller set 112.
By displacing the first translational roller 106 toward the metal sheet 12 in a displacement direction 126, and by displacing the second translational roller 108 toward the metal sheet 12 in a displacement direction 128 opposite to the displacement direction 126, contact with the metal sheet 12 and further controlled displacement of the translational rollers 106, 108 deforms and thereby increases each of a first length 130 and a second length 132 of the metal sheet 12 between the first roller set 110 and the second roller set 112. A rotational speed of the rollers of the second roller set 112 can also be varied (e.g., increased) from a rotational speed of the rollers of the first roller set 110 to permit longitudinal lengthening of the first and second lengths 130, 132 between the first roller set 110 and the second roller set 112.
Roller translation can directly be controlled using a feedback control system (not shown) designed for the above applications. A thickness reduction achieved for each of the above systems is mapped directly to a displacement in the roll of the metal sheet 12. A blank length can also be controlled by at least one of increasing the metal sheet feed speed, reducing the center-to- center spacing 98, 124 between the fixed roller sets, or decreasing a roller diameter of the translational rollers.
Referring to FIG. 7 and again to FIGS. 1 through 6, multiple exemplary component designs can be created using the variable thickness roll forming system 10 of the present disclosure. Following thickness reduction in one or more of the portions of the metal sheet 12, a drawn part 134 can be created. The central portion 26 having a greater thickness than the first outer portion 28 and the second outer portion 30 provides the thickness necessary to use a drawing process to form a drawn portion 136.
A flanged part 138 can be also created. The central portion 26 having a greater thickness than the first outer portion 28 and the second outer portion 30 can provide increased stiffness over an entire length of the flanged part 138. The first outer portion 28 and the second outer portion 30 can each define flanges that can be further modified such as to provide for a flange cutout 140 to suit installation requirements.
An assembly 142 can be created for exemplary use as a vehicle door frame. The central portion 26 can be used as a rigid web, while the first outer portion 28 can be reformed to support a window assembly, while the second outer portion 30 can be formed as a flange to longitudinally stiffen the assembly 142.
A tubular structure 144 can be created using for example two roll formed blanks 25 of the present disclosure. A first central portion 26(1) can be spaced apart from a second central portion 26(2) by joined, for example welded, first outer portions 28(1), 28(2) and joined second outer portions 30(1), 30(2).
Referring to FIGS. 8 and 9 and again to FIGS. 1 through 4, the metal sheet 12 is shown in an initial state as it is fed for example off a reel, and prior to any forming operations of the present disclosure. In its initial state, the metal sheet 12 with the planar body 20 initially has a uniform width 146 and a uniform thickness 148.
Referring to FIGS. 10 and 11, and again to FIGS. 8 through 9, following initial tailor roll forming the metal sheet 12 defines a tailor roll formed blank 150 having a rolled width 152 which is greater than the width 146. Opposed edges 154, 156 of the tailor roll formed blank 150 have a "wavy" shape due to the metal flowing laterally during the initial rolling operations. The wavy shape of the opposed edges 154, 156 is also due to the metal sheet 12 being unconstrained during the initial rolling operations. The first outer portion 28 and the second outer portion 30 have been work hardened by the action of the rollers, resulting in a material that has higher strength and stiffness than a metal sheet of similar reduced thickness that has not been work hardened. Therefore, in addition to reducing a mass by reducing portion thickness, the physical properties of the metal sheet 12 in the areas of the first outer portion 28 and the second outer portion 30 are also enhanced. It is noted that work hardening is more effective in steel materials than aluminum materials. The center portion 26 remains not work hardened.
Referring to FIGS. 12 and 13 and again to FIGS. 8 through 11, a sheet 158 is shown after an edge trimming operation is performed on the tailor roll formed blank 150. The edge trimming operation forms the sheet 158 having a width 160, where the width 160 is less than the rolled width 152, but can be greater than, less than, or the same as the original width 146 of the metal sheet 12. Edge trimming is performed to provide sheet 158 with consistent, parallel and linear opposed outer edges 162, 164. After edge trimming, portions of the sheet 158 are still work hardened.
Referring to FIGS. 14 and 15 and again to FIGS. 8 through 13, following all operations of the variable thickness roll forming system 10 of the present disclosure, an exemplary finished part 166 is shown. Finished part 166 takes advantage of the differing thicknesses of the sheet 158, for example having the first outer portion 28 and the second outer portion 30 of a reduced thickness compared to the center portion 26, while the work hardening provided by the variable thickness roll forming system 10 provides specific predetermined strength and weight requirements for the finished part 166. While reference has been made herein to an exemplary initial metal sheet thickness of approximately 2.00 mm with reductions made thereafter, the reduced thickness edge portions defining the first outer portion 28 and the second outer portion 30 can be selectively reduced by approximately 30-40% below any initial metal sheet thickness in the finished part. Therefore, the thickness of the first outer portion 28 and the thickness of the second outer portion 30 may be reduced by up to approximately 40% of the thickness of the central portion 26 after passing through a final one of the sets of rollers. This allows for significant weight savings in the finished part while retaining enough thickness for strength, particularly when the material of the metal sheet 12 is a steel allowing the maximum benefit from work hardening.
Referring to FIG. 16, a graph 168 presents strain amounts in different areas of an exemplary roll formed blank 170 formed using the variable thickness roll forming system 10 of the present disclosure. Predominant portions indicated in a first strain zone 172 exhibit strain amounts below a predetermined "safe" strain. Portions of the roll formed blank 170 indicated in a second strain zone 174 define areas deemed to provide insufficient stretching and therefore elevated strain. Portions of the roll formed blank 170 indicated in a third strain zone 176 define areas trending to exhibit minor plate wrinkling due to the roll forming process. Portions of the roll formed blank 170 indicated in a fourth strain zone 178 define areas having a trend to exhibit strong or significant plate wrinkling due to the roll forming process.
Referring to FIG. 17 and again to FIG. 16, a forming limit diagram 180 presents exemplary minor versus major strain data 182 for roll formed blanks such as the roll formed blank 170 depicted in FIG. 16 made using the variable thickness roll forming system 10 of the present disclosure. All of the data 182 is significantly below a curve 184 defining maximum allowable strain values, indicating roll formed blanks made using the variable thickness roll forming system 10 of the present disclosure do not exhibit material cracking or failure due to strain introduced during the rolling process which introduces both material thinning and work hardening.
The variable thickness roll forming system 10 of the present disclosure offers several advantages. These include the ability to accurately provide incremental thickness reductions in a metal blank while maintaining a cost effective minimum feed speed for all of the roller sets. This is in lieu of imparting all of the desired thickness reduction using only a single roller set, which may reduce an overall feed speed compared to a feed speed achieved by only applying an incremental thickness reduction over multiple roller sets.

Claims

A variable thickness roll forming system (10) for forming a variable thickness blank from a metal sheet (12) passing through at least two sets of rollers, the roll forming system (10) comprising:
- at least two sets of cylindrical shaped rollers, each of the at least two sets of rollers including:
∘ a first roller (38) including a face (42) which is linear where the first roller (38) is adapted to contact the metal sheet (12); and

∘ a second roller (40) including multiple shaping faces positioned about a perimeter and directed toward the face (42) of the first roller (38);

- each of the at least two sets of rollers adapted to incrementally alter a thickness of the metal sheet (12) in at least a direction transverse to a feed direction (18, 122) of the metal sheet (12) when the metal sheet (12) is passed between the first roller (38) and the second roller (40);
wherein the first roller (38) and the second roller (40) are adapted to form a roll formed blank (25) having a first portion and at least a second portion positioned in the direction transverse to the feed direction (18, 122) of the metal sheet (12) with respect to the first portion, the first portion having a thickness greater than a thickness of the second portion,

characterized in that

the variable thickness roll forming system (10) includes a translational roller (80, 106, 108) positioned between a first roller set (82, 110) of the multiple roller sets and a second roller set (84, 112) of the multiple roller sets, said translational roller (80, 106, 108) being adapted to be displaced in a displacement direction (100, 126,128) substantially transverse to the metal sheet (12) and toward the metal sheet (12) to lengthen the metal sheet (12) between the first roller set (82, 110) and the second roller set (84, 112).
The variable thickness roll forming system (10) of claim 1, wherein the multiple shaping faces of the second roller (40) include a first shaping face (44) which defines a first spacing distance (46) between the first shaping face (44) and the face (42) of the first roller (38).
The variable thickness roll forming system (10) of claim 2, wherein the second roller (40) further includes a second shaping face (48) defining a second spacing distance (50) between the second shaping face (48) and the face (42) of the first roller (38) which is less than the first spacing distance (46).
The variable thickness roll forming system (10) of claim 3, wherein the second roller (40) further includes a third shaping face (52) defining a third spacing distance (54) between the third shaping face (52) and the face (42) of the first roller (38) which is less than the second spacing distance.
The variable thickness roll forming system (10) of claim 4, wherein:
- the second spacing distance (50) defines a thickness of the second portion of the roll formed blank (25); and

- the third spacing distance (54) defines a thickness of a third portion of the roll formed blank (25) oppositely positioned about the first portion (26) with respect to the second portion.
The variable thickness roll forming system (10) of any one of the preceding claims, wherein the thickness of the second portion is reduced by up to approximately 40% of the thickness of the first portion (26).
The variable thickness roll forming system (10) of any one of the preceding claims, wherein the translational roller is a single translational roller (80) defining a single offset roller system (86) positioned between the first roller set (82) of the multiple roller sets and the second roller set (84) of the multiple roller sets, wherein the translational roller (80) is adapted to be displaced toward the metal sheet (12) in a displacement direction (100) substantially transverse to the metal sheet (12) and to deform and thereby laterally lengthen a length of the metal sheet (12) between the first roller set (82) and the second roller set (84).
The variable thickness roll forming system (10) of any of the preceding claims 1 to 6, wherein the translational roller (106) is the first translational roller (106) of a dual offset roller system (104 ) positioned between the first roller set (110) and the second roller set (112), the dual offset roller system further including a second translational roller (108) being positioned oppositely about the metal sheet (12) with respect to the first translational roller (106), wherein the first translational roller (106) is adapted to be displaced toward the metal sheet (12) in a displacement direction (126) substantially transverse to the metal sheet (12) in order to deform and thereby laterally lengthen a length of the metal sheet (12) between the first roller set (110) and the second roller set (112) and wherein the second translational roller (108) is adapted to be displaced toward the metal sheet (12) in a direction opposite to the displacement direction (126) of the first translational roller (106) in order to deform and thereby lengthen a further portion of the metal sheet (12).
The variable thickness roll forming system (10) of any of the preceding claims, wherein the system is adapted to form the roll formed blank such that when the metal sheet (12) passed between the first roller (38) and the second roller (40) the roll formed blank (25) has a central portion (26) being the first portion, a first outer portion (28) being the second portion, and a second outer portion (30) located opposite about the central portion (26) with respect to the first outer portion (28), the central portion (26) having a thickness greater than a thickness of each of the first outer portion (28) and the second outer portion (30).
The variable thickness roll forming system (10) of claim 9, wherein the system is adapted to form the roll formed blank such that after the metal sheet (12) passed through a final one of the sets of rollers the thickness of the central portion (26) is substantially equal to an initial thickness (22) of the metal sheet (12).
The variable thickness roll forming system (10) of claims 9 or 10 , wherein the system is adapted to form the roll formed blank such that after the metal sheet (12) passed through a final one of the sets of rollers the thickness of each of the first outer portion (28) and the second outer portion (30) of the metal sheet (12) is substantially equal or the thickness of one of the first outer portion (28) and the second outer portion (30) is greater than the thickness of the other one of the first outer portion (28) and the second outer portion (30).
The variable thickness roll forming system (10) of claims 9 or 10, wherein the system is adapted to form the roll formed blank such that after the metal sheet (12) passed through a final one of the sets of rollers the thickness of the first outer portion (28) and the thickness of the second outer portion (30) of the metal sheet (12) are reduced by up to approximately 40% of the thickness of the central portion (26).
A method for forming a variable thickness blank, comprising:
- aligning multiple sets of cylindrical shaped rollers, each of the multiple sets of rollers including:
∘ a first roller (38) having a face (42) which is linear where the first roller (38) contacts the metal sheet (12); and

∘ a second roller (40) having multiple shaping faces positioned about a perimeter and directed toward the face (42) of the first roller (38); and

- passing a metal sheet (12) through each of the sets of rollers to incrementally induce multiple thickness changes of the metal sheet (12) in a direction transverse to a feed direction (18) of the metal sheet (12) when the metal sheet (12) is passed between the first roller (38) and the second roller (40) of each of the sets of rollers,
characterized by the additional method step of displacing a translational roller (80, 106, 108) positioned between a first roller set (82, 110) of the multiple roller sets and a second roller set (84, 112) of the multiple roller sets in a displacement direction (100, 126,128) substantially transverse to the metal sheet (12) and toward the metal sheet (12) to lengthen the metal sheet (12) between the first roller set (82, 110) and the second roller set (84, 112).
A method for forming a variable thickness blank according to claim 13, including the method step of either
- displacing the translational roller (80) as a single translational roller (80) defining a single offset roller system (86) in a displacement direction (100) substantially transverse to the metal sheet (12) and toward the metal sheet (12) to lengthen the metal sheet (12) between the first roller set (82) and the second roller set (84), or of

- displacing the translational roller (80) as a first translational roller (106) of a dual offset roller system (104) in a displacement direction (126) toward the metal sheet (12) and substantially transverse to the metal sheet (12) to lengthen the metal sheet (12) between the first roller set (110) and the second roller set (112), and displacing a second translational roller (108) of the dual offset roller system (104) being positioned oppositely about the metal sheet (12) with respect to the first translational roller (106) in a displacement direction (128) opposite to the displacement direction (126) of the first translational roller (106) toward the metal sheet (12) and substantially transverse to the metal sheet (12) to lengthen a further portion of the metal sheet (12) between the first roller set (110) and the second roller set (112).
The method for forming a variable thickness blank of claim 14, further including:
- setting a first spacing distance (46) between a first shaping face (44) of the multiple shaping faces of the second roller (40) and the face (42) of the first roller (38) substantially equal to an initial thickness (22) of the metal sheet (12);

- setting a second spacing distance (50) between a second shaping face (48) of the multiple shaping faces of the second roller (40) and the face (42) of the first roller (38) less than an initial thickness (22) of the metal sheet (12);

- setting a third spacing distance (54) between a third shaping face (52) of the multiple shaping faces of the second roller (40) and the face (42) of the first roller (38) less than the initial thickness (22) of the metal sheet (12), and preferably further including

- positioning the first, second and third shaping faces (44, 48, 52) wherein the metal sheet (12) when passed between the first roller (38) and the second roller (40) forms a roll formed blank (25) having a central portion (26), a first outer portion (28) and a second outer portion (30) located opposite about the central portion (26) with respect to the first outer portion (28), the central portion (26) having a thickness greater than a thickness of the first outer portion (28) and the second outer portion (30).