AUTOMOTIVE CRUSH TIP AND METHOD OF MANUFACTURING
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60/617,394, filed on October 8, 2003. The entire contents of the disclosures of the above applications are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to tubular members designed to collapse generally transverse to a longitudinal axis thereof in the event of an impact thereto in order to absorb energy and press-forming methods of manufacturing such tubular members.
BACKGROUND OF THE INVENTION [0003] This patent application applies to automotive crush tips which are integrated in an automotive structure to absorb energy in the event of a collision. Crush tips are designed to collapse generally along their length to absorb energy in the event of a front or rear end collision, thereby minimizing damage to occupants for both vehicles involved in the crash. Consequently, crush tips have longitudinal axes which are generally oriented parallel with the longitudinal axis of the vehicle between its front and back.
[0004] Automotive crush tips are typically manufactured by MIG welding two overlapping press formed C-channels. Using this manufacturing process two separate C-channels are first formed. Then they are brought together in facing relationship and accurately positioned so that the ends overlap each other slightly. Then a welding operation - typically MIG welding - is performed along each of the overlapping ends to create two welded seams. Then attachment flanges or other features are typically welded to the C-channels to finalize the manufacturing process. [0005] More recently, tube hydroforming has also been used as another viable option for manufacturing automotive crush tips. In this manufacturing process, a tube is first formed. The tube is then subjected to a hydroforming process. During hydroforming, fluid pressure is applied to the interior of the tube, causing the tube to expand and conform to a surrounding mold cavity. Like the C-channel process, attachment flanges or other features are then typically welded to the hydroformed structure to finalize the manufacturing process.
[0006] Each of these manufacturing processes has various disadvantages. For example, they are both generally inefficient and/or costly. For example, additional unnecessary weight results from using overlapping C- channels. In addition, there can be significant limitations in the geometry and/or structure of the final product as a result of the manufacturing process. MIG welding two seams can also create undesireable localized stresses, for example, due to the heat involved. With hydroforming, for example, large portions of the crush tube material are thinned and work hardened, thereby decreasing its energy absorbing properties. [0007] Further, they have various disadvantages when today's high- strength steels are used to form the crush tips. For example, hydroforming can require substantial forming pressures when high-strength steel is used. In addition, many high strength steels are not suitable for the typical MIG welding process.
SUMMARY OF THE DISCLOSURE
[0008] In one aspect of the disclosure an automotive crush tip includes a tubular member having a longitudinal weld seam joining the opposing side edges of an integral blank together. The automotive crush tip includes a plurality of transverse collapse initiating features located in the tubular member. At least a portion of the material of the integral blank and the tubular member has not been strain hardened.
[0009] In another aspect of the disclosure an automotive crush tip includes a tubular member having at least two side wall portions connected together by a corner portion that is straight. At least one of the at least two side wall portions has an expanded material portion adjacent the straight corner portion. [0010] In an additional aspect of the disclosure an automotive crush tip includes a tubular member having at least one expanded wall area including a wall thickness that has been thinned, and the tubular member having at least one unexpanded wall area including a wall thickness that has not been thinned. [0011] In yet another aspect of the disclosure a method useful for manufacturing an automotive crush tip includes forming a blank having opposing longitudinal side edges. In addition, the blank is formed into a substantially tubular member wherein the opposing longitudinal side edges are adjacent to each other. The opposing longitudinal side edges of the blank are welded together. At least one structural feature is formed in the blank prior to welding.
[0012] In a further aspect of the disclosure a method useful for manufacturing an automotive crush tip includes forming a substantially flat blank having opposing side edges. The substantially flat blank is formed into a wall having a partially tubular shape. The wall is formed into a substantially tubular shape wherein the opposing side edges are adjacent to each other. The opposing side edges are welded together to form the wall into a tubular shape, at least one structural feature is formed in the wall simultaneously with at least one of forming a substantially flat blank, forming a partially tubular wall, and forming a substantially tubular wall. [0013] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
[0015] Figure 1 is a perspective view of an exemplary embodiment of a crush tip from the front thereof;
[0016] Figure 2 is a perspective view of the exemplary embodiment of the crush tip of Figure 1 from the back thereof; [0017] Figure 3 is a perspective view of an exemplary blank for forming the crush tip of Figure 1 ;
[0018] Figure 4 is a perspective view of the blank of Figure 3 after it has been subjected to some initial press-forming operation(s); [0019] Figure 5 is a perspective view of the blank of Figure 3 after it has been subjected to some additional press-forming operation(s);
[0020] Figure 6 is a perspective view of the blank of Figure 5 in the form of a substantially tubular member;
[0021] Figure 7 is a perspective view of the blank of Figure 5 in the form of a tubular member including a longitudinal weld seam;
[0022] Figure 8 is a perspective view of another exemplary embodiment of a crush tip from the front thereof;
[0023] Figure 9 is a perspective view of the exemplary embodiment of the crush tip of Figure 8 from the back thereof; [0024] Figure 10 is a perspective view of an exemplary blank for forming the crush tip of Figure 8;
[0025] Figure 11 is a perspective view of the blank of Figure 10 after it has been subjected to some initial press-forming operation(s);
[0026] Figure 12 is a perspective view of the blank of Figure 11 after it has been subjected to some additional press-forming operation(s);
[0027] Figure 13 is a perspective view of the blank of Figure 12 in the form of a substantially tubular member;
[0028] Figure 13 is a perspective view of the blank of Figure 13 in the form of a tubular member including a longitudinal weld seam; [0029] Figure 15 is a top plan view of a third exemplary blank for forming a crush tip;
[0030] Figure 16 is a top plan view of a forth exemplary blank for forming a crush tip; and
[0031] Figure 17 is a flow chart describing a press-forming manufacturing process for shaping substantially flat blanks into additional embodiments of tubular crush tips. DETAILED DESCRIPTION OF THE EMBODIMENTS [0032] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. As but one example, although the crush tip of the embodiments illustrated herein have tubular members with a generally rectangular cross-section, other cross-sectional shapes are possible such as circular, hexagonal, square, and/or combinations thereof.
[0033] Referring to Figures 1 and 2, an exemplary embodiment of a crush tip 10 is illustrated as a substantially tubular member 12 defined by two side walls 14, a top wall 16 and a bottom wall 18. Each side wall 14 is connected to the bottom wall 18 along respective corner portions 20, that can be straight. Each side wall 14 is also connected to the top wall 16 along respective corner portions 20 that are comprised of two straight (generally longitudinally oriented) segments 20' and 20" joined together at an angle with respect to each other. A longitudinal weld seam 21 is provided in the top wall 16 as seen in Figure 7. The cross-section of the tubular member 12 defined by the walls 14, 16, 18 varies along its longitudinal axis. In other words, the overall dimensions and/or the overall shape of the transverse cross-section of the tubular member 12 is different at different points along the length of the tubular member 12. [0034] The tubular member 12 includes a plurality of various structural features. The structural features can be attachment features and/or transverse collapse initiating features. With respect to attachment features, for example, the side walls 14 of the tubular member 12 include a plurality of openings 22. At least some of these openings 22 can be used in attaching the crush tip 10 to components of an automobile. In addition, end flanges 24 or other edge attachments can be provided for attaching the crush tip 10 to automobile components.
[0035] Another example of structural features that can be provided are transverse collapse initiating features. These transverse collapse initiation features help facilitate collapse of the crush tip 10 in a direction that is generally transverse to a longitudinal axis of the tubular member 12. These transverse collapse initiating features can be protrusions or depressions that are formed in a blank while it is in its flat configuration or as the blank is being formed into a tubular member 12 as described hereinafter.
[0036] For example, depressions 26 that extend inwardly can be formed in the corner portions 20 connecting the two side walls 14 to the top wall 16 and the bottom wall 18 of the tubular member 12. These depressions 26 are formed as darts that have boundaries that can be substantially transverse to a longitudinal axis of the tubular member 12. Such substantially transverse boundaries can aid the generally transverse collapse of the crush tip 10. Because these darts 26 are formed by expanding an area of material as discussed hereinafter, the material can be thinned and/or strain hardened relative to the surrounding material of the tubular member 12.
[0037] Collapse initiating features in the form of protrusions 28 that extend outwardly are also provided. Two protrusions 28 are located in each side wall 14. Each of the protrusions 28 are positioned in each side wall 14 adjacent at least one straight corner portion 20. In this embodiment, the two protrusions 28 are located in the side walls 14 adjacent the straight corner portions 20' connecting each side wall 14 with the bottom wall 18. Additionally, the two protrusions 28 are located in each side wall 14 adjacent straight corner portions 20' connecting the side wall 14 with the top wall 16. Although "side wall", "top wall", and "bottom wall" are referred to herein to aid in clarity, each of these walls 14, 16, 18 is also generically referred to herein as a "side wall" or "wall" of the tubular member 12.
[0038] Like the depressions 26, these protrusions 28 can include at least one boundary 28' that is substantially transverse to the longitudinal axis of the tubular member 12. Each of the transverse boundaries 28' of the protrusions 28 can be generally aligned with one of the depressions 26 and visa versa. In addition, the substantially transverse boundary 28' of the protrusion 28 can be substantially aligned with a transverse boundary 26' of a depression 26 or another collapse initiating feature. Such alignment configurations can further facilitate collapsing of the crush tip 10 generally along its longitudinal length as a result of the crush initiation features 26, 28. These protrusions 28 can be formed by expanding an area of material and the material can be thinned and/or strain hardened relative to the surrounding material of the tubular member 12 as a result.
[0039] Referring to Figure 3, a blank 30 used to form an exemplary embodiment of an automobile crush tip 10 is provided. The blank 30 can be initially substantially flat. The blank 30 includes portions 32' of opposing longitudinal side edges 32 that are not parallel (i.e., they are angled) with respect to each other. Thus, the portion of the flat blank 30 of this embodiment that corresponds to the opposing longitudinal side edges 32' that are not parallel has a generally trapezoidal shape. In addition, the blank 30 includes portions 32" of opposing longitudinal side edges 32 that are parallel with each other. Thus, the corresponding portion of the flat blank 30 has a generally rectangular shape. Because the flat blank 30 includes opposing side edges 32' that are not parallel to each other, the cross-section of the resulting tubular member 12 varies along its longitudinal length. [0040] Various structural features can be formed in the blank 30 as desired. One example of such structural features are attachment features which can include attachment openings 22 and attachment flanges 24. For example, attachment openings 22 can be formed as part of the process of forming the blank 30 using a blanking die. In addition, attachment features can include end flanges 24 that can be formed as part of the process of forming the blank 30 using a blanking die. These attachment features can alternatively be formed as a separate step from that of forming the substantially flat blank 30. For example, the attachment openings 22 can be formed as a result of a separate piercing step. It can be preferable to form all or most of these structural features prior to welding the longitudinal seam 21 of the tubular member 12 as described hereinafter.
[0041] Referring to Figure 4, the blank 30 is illustrated as having been subjected to a partial forming operation, resulting in a wall having a partially tubular shape which can include one or more separate steps. Several structural features have been at least partially formed as a result of this partial forming operation, which can occur as one simultaneous step or as sequential steps. The end flanges 24 have been partially formed and trimmed as part of a single step. Alternatively, the end flanges 24 may be partially formed and trimmed as two separate steps. Similarly, the longitudinal side edges 32 can be trimmed, for example, as part of the blank 30 forming process or using a separate skiving operation. [0042] In this embodiment, two sections 16' of the top wall 16 are bent up at roughly a 90 degree angle along each of the opposing side edges 32. Thus, the bend forms a corner portion 20 between two side wall portions 16'. The corner portion 20 can be formed as part of a press-forming operation. In addition, the collapse initiating depressions 26 can be formed in the corner portions 20. Furthermore, the collapse initiating protrusions 28 can be formed using appropriate male and female die components. It can be preferable to form all of these components as part of a single die strike that includes the wall press- forming operation. Alternatively, multiple sequential die strikes and/or press- forming operations can be used. [0043] Referring to Figure 5, the blank 30 is subjected to a subsequent press-forming operation to create a corner portion 20 between each of the side walls 14 and the bottom wall 18 of the blank 30. As part of this press-forming operation additional collapse initiating depressions 26 can be press-formed into the newly created corner portions 20 connecting the side walls 14 to the bottom wall 18. Again, the wall formation and the collapse initiating depression formation can occur simultaneously or sequentially. Simultaneous forming of such features can be preferred. The side edges 32 can be trimmed, if it has not already been done. As illustrated in Figures 4 and 5, the substantially flat blank 30 has been formed into a wall (comprised of top wall sections 16', side walls 14 and bottom wall 18) having a partially tubular shape.
[0044] Referring to Figure 6, the side walls 14 are then moved together so that the side edges 32 are located adjacent to each other to form a substantially tubular member. Because the material of the blank 30 has a tendency to spring back there is typically a gap extending longitudinally between the opposing side edges 32. As illustrated in Figure 6, the wall (comprised of top wall sections 16', side walls 14 and bottom wall 18) has been formed into a substantially tubular shape. [0045] Referring to Figure 7, an opposing force can be applied to opposing side walls 14 of the substantially tubular member 12 to bring the longitudinal side edges 32 into a zero gap configuration. With the side edges 32 in this position, the side edges 32 are welded together along weld line 21 , thereby forming the tubular member 12. Any suitable welding operation can be used, including laser welding, gas metal arc welding, Tungsen inert gas, high frequency welding, mash seam welding, friction stir welding, or the like. Laser welding can be a preferred welding process. As illustrated in Figure 6, the wall (comprising top wall 16, side walls 14 and bottom wall 18) has been formed into a tubular shape, thereby creating a tubular member 12.
[0046] As a result of this forming process, portions of the material that define the crush tip 10 have been expanded, which can result in the material being thinned and/or which can result in strain hardening of the material. For example, the transverse crush initiating features are protrusions 28 and/or depressions 26 that are expanded from an initially substantially flat sheet of material, thereby thinning and/or work hardening the material. The remaining portions of the crush tip 10 can be made from material that has not been expanded, thinned and/or work hardened.
[0047] In contrast, hydroforming typically provides more hardening and/or material thinning. In fact, with hydroforming, material thinning and/or strain hardening can extend over substantially the entire surface area of the crush tip. Thus, hydroforming can result in an all over reduction in capacity for absorbing energy. It can be preferable that the expansion, work hardening and/or material thinning of this press-forming process occurs over 75% or less of the surface area or the crush tip 10; more preferably, 60% or less; and even more preferably 50% or less. The press-forming process also provides sharp feature realization and enhances the function of structural features of the crush tip 10.
[0048] Also as a result of the above-described manufacturing process, there can be no need to perform any post-welding shaping operations. In many cases, the tubular member 12 that results from welding the longitudinal seam 21 provides a crush tip 10 in its substantially final shape. In other words, subsequent minor shaping operations may occur, such as bending an attachment flange outwardly. It can be preferred, however, that none of the material expanding that results in material thinning and/or work hardening occurs after the welding of the longitudinal seam 21. [0049] Referring to Figures 8 and 9, another embodiment of an exemplary crush tip 110 includes a first portion 112' of the tubular member 112 that has one of a material, a thickness, or both, that is different from another portion 112" of the tubular member 112. In this embodiment, the tubular member 112 can be formed from a substantially flat blank that comprises two sub-blanks as described hereinafter. Of course, the previous embodiment could also be formed of two sub-blanks welded together. The first sub-blank, and therefore a first portion 112' of the tubular member 112, has a thickness that is different from the second sub-blank, and therefore from a second portion 112" of the tubular member 112. In addition, the material of the first sub-blank and corresponding tubular portion 112' is a different material than the material of the second sub-blank and corresponding tubular portion 112".
[0050] Similar to the embodiment of Figures 1 and 2, the tubular member of this embodiment includes transverse crush initiation features in the form of depressions 126 as darts located in the straight corner portion 120 joining the side walls 114 with the top wall 116 and bottom wall 118. This embodiment also includes attachment features in the form of attachment flanges 124 extending from the ends of the tubular member. Each of the attachment flanges 124 includes an aperture 125 therein for receiving a fastener. The attachment flanges 124 can be left in their generally longitudinally extending direction as illustrated. Alternatively, the attachment flanges 124 can be bent into a generally transversely extending direction.
[0051] Referring to Figure 10, a blank 130 used to form an exemplary embodiment of the automobile crush tip 110 of Figures 8 and 9 is illustrated. The blank 130 is initially flat and has a generally trapezoidal overall shape including opposing side edges 132 that are not parallel. This blank however, is formed from two sub-blanks 131 , 133. The first sub-blank 131 is made from a material that is different than that of the second-sub-blank 133. For example, the first sub-blank 131 can be made of steel and the second sub-blank 133 could be made of a different, high strength, steel. An alternative way to provide a first sub-blank 131 that is of a different material than a second sub-blank 133 is to treat or surface coat one of the sub-blanks 131 , 133, thereby giving the sub- blanks 131 , 133 different material properties. As one possible variant, one of the sub-blanks 131 , 133 can be subjected to a heat treating process that alters the structure of the steel.
[0052] In addition, the first sub-blank 131 can have a material thickness that is thinner than that of the second sub-blank 133. The first sub- blank 131 and the second sub-blank 133 can be welded together along a boundary or joint line 137. Any suitable welding operation can be used, including laser welding, gas metal arc welding, Tungsen inert gas, high frequency welding, mash seam welding, friction stir welding, or the like. Laser welding can be a preferred welding process. As used herein, the term "sub- blank" refers both to those instances where separate blanks are joined together and to those instances where portions of a one-piece blank are different from each other.
[0053] Attachment features in the form of apertures 122 can be stamped along with the forming of the blank 130 or sub-blanks 131 , 133. Alternatively, the apertures 122 can be formed as part of a piercing operation. This piercing operation can be a completely separate step, or it can be a part of a forming operation or press-forming operation associated with forming up the walls (e.g., 16', 16"). In addition the piercing operation can occur simultaneously or sequentially with wall forming operations. [0054] Referring to Figure 11 , the blank 130 is illustrated as having been subjected to a partial wall forming operation, which can include one or more simultaneous or sequential steps. Several features have been formed as a result of this partial forming operation. In this embodiment, two segments of the top wall 116', 116" are bent up at roughly a 90 degree angle adjacent each of the opposing side edges 132. Thus, the bend forms a corner portion 120 between two top wall portions116', 116" and the adjacent portion of the blank 130. The corner portions 120 can be formed as part of a press-forming operation. In addition, the collapse initiating depressions 126 are formed in the corner portions 120. It can be preferable to form all of these components as part of a single die strike that includes the press-forming operation. Alternatively, multiple die strikes and/or press-forming operations can be used. [0055] Referring to Figure 12, the blank is subjected to a subsequent press-forming operation to create a corner portion 120 between each of the side walls 114 and the bottom wall 118 of the blank 130. As part of this press-forming operation, additional collapse initiating depressions 126 can be press-formed into the blank. Alternatively these collapse initiating depressions 126 can be formed separately from this press-forming operation forming the corner portions 120. If it has not already been done, the opposing longitudinal side edges 132 can then be trimmed, or subjected to a skiving operation in order to ensure a good fit between the opposing side edges 132.
[0056] Referring to Figures 13 and 14, the sides are then moved together so that the opposing side edges 132 are located adjacent to each other to form a substantially tubular member. An opposing force can be applied to each of the opposing sides of the substantially tubular member to bring the longitudinal side edges 132 into a zero gap configuration. With the side edges 132 in this position, the side edges 132 can be welded or otherwise joined together along a longitudinal joint line 121 as discussed above.
[0057] Figures 15 and 16 illustrate various substantially flat blanks
230, 330 that can be used to create alternative crush tip embodiments. These substantially flat blanks 230, 330 as illustrated each include three sub-blanks
231 , 233 and 235; and 331 , 333, and 335, respectively. Boundary lines or joint lines 237, 337 define each sub-blank relative to the adjacent sub-blanks. Joining separate sub-blanks together, for example, by welding, can create the boundary lines or joint lines 237, 337. In addition, one section of a single one-piece blank can be coated or otherwise treated to provide a sub-blank having a different material than that of another untreated portion defining another sub-blank. As another alternative, different sections of a one-piece blank can be rolled to different thicknesses to create the sub-blanks. [0058] In all of the instances outlined above, the integral substantially flat blank 230, 330 includes a boundary line or joint 237 and 337, respectively, line between the sub-blanks thereof. The boundary lines 237, 337 can take on a variety of shapes. For example, the boundary lines 237 of Figure 15 are aligned substantially transversely to the longitudinal axis of the blank 230. The boundary lines 337 of Figure 16 have both lateral and transverse directional components. Although the boundary lines 237, 337 of these embodiments are illustrated as being straight, the boundary lines may also include arcuate shapes. In addition, although the boundary lines 237, 337 of these embodiments are illustrated as being parallel to the other boundary lines of the blank 230, 330, a blank can include a boundary lines that are different from the other boundary lines of a blank. Further, the thickness of the boundary line can be variable. Thus, a large degree of flexibility is provided to design the collapse characteristics of a crush tip made using these blanks. [0059] Referring to a specific embodiment of a blank 230 in accordance with Figure 15, the illustrated flat blank 230 is comprised of three separate sub-blanks 231 , 233, 235. Each of sub-blanks 231 and 233 are rolled from a single piece of material, but the material of sub-blank 231 is rolled to a thinner dimension than that of sub-blank 233. Thus, a difference in thickness occurs at boundary line 237 between sub-blank 321 and sub-blank 233. Sub- blank 235 is initially formed from a separate piece of the same material having the same thickness as that of sub-blank 233. The material of this sub-blank 235, however, is subjected to a heat treatment process which alters the material of the sub-blank 235. Thus, sub-blank 235 has a different material than that of sub- blank 233 and has both a different material and a different thickness than that of sub-blank 231. Sub-blank 235 can be welded to sub-blank 233 along the corresponding joint or boundary line 237.
[0060] Referring to a specific embodiment of a blank 330 in accordance with Figure 16, the illustrated flat blank 330 is comprised of three separate sub-blanks 331 , 333, 335. Each of the sub-blanks 331 , 333, 335 can be stamped or otherwise formed from flat sheets of different material having different thicknesses. Each of the end sub-blanks 331 and 335 is then joined to the central sub-blank 333 along a corresponding joint line or boundary line 337. The sub-blanks 331 , 333, 335 can be joined together by a welding operation that is suitable for the material, including laser welding, gas metal arc welding, Tungsen inert gas, high frequency welding, mash seam welding, friction stir welding, or the like.
[0061] Referring to Figure 17, each of the blanks of Figures 15 and 16 can be formed into other embodiments of a crush tip using a progressive or transfer die press-forming process as outlined therein and as described above. As noted in block 40 a blank is loaded or coil fed into a forming station. The blank referred to therein is an integral, substantially flat blank from which the tubular member is formed. As indicated in block 42, this integral blank can be subjected to one or more operations, either simultaneously or sequentially. For example, the integral blank can be trimmed. Additionally, holes can be pierced or otherwise formed therein. Further, structural features can be formed therein as a result of a press forming operation. The structural features can include attachment features and/or the transverse collapse initiating features. In addition, wall components of the tubular member can be partially formed by press-forming corner portions to create wall sections separated thereby.
[0062] The integral blank discussed above with respect to blocks 40 and 42 can be formed from sub-blanks which may, themselves, have been subjected to steps similar to those of blocks 40 and 42. For example a blank for a sub-blank can be loaded or coil fed into a forming station. This sub-blank can be trimmed, for example, prior to joining with other sub-blanks. As discussed above, the sub-blanks can then be joined together by welding to create an integral blank having joint lines or boundary lines. Although the sub-blank may be subjected to a piercing operation to form holes therein and/or have features press-formed therein, it can be preferred that these operations occur after the sub-blanks have been joined together into an integral blank.
[0063] Referring to blocks 44 and 46, additional press forming operations can be provided to form additional features, either simultaneously or sequentially. For example, wall components of the tubular member can be more completely formed by further press-forming corner portions to create wall sections separated thereby and to form the blank into a substantially tubular member. Simultaneously or sequentially, further structural features can be formed therein as a result of a press forming operation and/or holes can be pierced or otherwise formed therein. [0064] Referring to block 48, the substantially tubular member that is formed above provides the opposing side walls adjacent to each other with a small gap therebetween. Opposing forces can be applied to the substantially tubular member to hold the gap closed and then the opposing side edges can be welded together to form a longitudinal butt weld seam. As indicated in block 50, the final part is then unloaded. As noted above, it can be preferred that no post welding forming steps occur. In some cases, holes or other features can alternatively be created after the tube is formed; particularly where tight tolerances are required.
[0065] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.