Hydroforming using non-isometric weld orifice extrusion

Abstract

The present disclosure provides "Hydroforming with Orifice Extrusion of Non-Isometric Welds." A method of forming a part includes extruding a billet through a die; forming a circular closed geometric tube from the billet; and hydroforming the circular closed geometric tube. The extrusion die includes a bore having a central mandrel, a plurality of bridges, and a corresponding plurality of orifices between the bridges. The spacing of the bridges around the mandrel is non-isometric. As a result, the circular closed geometric tube has a non-isometric weld after coming out of the die.

Description

Technical Field

[0001] This disclosure relates to aluminum extruded tubes for automotive applications. Background Technology

[0002] The descriptions in this section are provided only as background information in relation to this disclosure and may not constitute prior art.

[0003] Vehicle manufacturers are implementing lighter, stronger materials, such as aluminum alloys, to meet emissions reduction targets, fuel economy goals, lower manufacturing costs, and reduce vehicle weight. Increasingly stringent safety standards must be met while simultaneously reducing vehicle weight. One way to achieve these competing interests and goals is to hydraulically press high-strength aluminum alloy billets into strong, lightweight parts.

[0004] Aluminum tubes used for this purpose include extruded seamless tubes and extruded structured tubes. Extruded seamless tubes are relatively expensive, while extruded structured tubes are less expensive because of the improved performance of the structured extrusion process, in which multiple profiles can be extruded simultaneously.

[0005] Extruded tubes are formed by extruding aluminum billets through an extrusion die under high temperature and pressure. Discontinuous material flow occurs across the section shape as the flowing aluminum separates in the mandrel plate and reconverges in the cap section. Weld lines or joint lines are formed at the reconvergence points of the flowing aluminum to form the extruded shape. Extruded tubes (also called orifice tubes) may have two or more weld lines, which are artifacts of the extrusion process.

[0006] Extruded structural tubes can then undergo a series of processing operations, such as bending, preforming, hydroforming, piercing, and machining, to form parts of the desired complex shapes. The weld lines in extruded structural tubes have relatively low ductility and can withstand relatively low stress / strain. During the series of processing operations, extruded structural tubes may break at the weld lines.

[0007] This disclosure solves the problems of structural tube breakage in hydroforming operations and other tube forming operations. Summary of the Invention

[0008] In one form, a method for forming a part is provided, the method comprising: extruding material through a die; forming a circularly closed geometric tube from the material; shaping the circularly closed geometric tube into an intermediate shape; and hydroforming the intermediate shape into the part. The die includes a bore having a central mandrel, a plurality of bridging members, and corresponding plurality of orifices between the bridging members. The spacing between the bridging members around the central mandrel is non-equiangular. Therefore, the circularly closed geometric tube has non-equiangular welds after exiting the die.

[0009] Among other features, the mold includes a plurality of holes, each hole having a central mandrel, a plurality of bridging members, and corresponding plurality of orifices between the bridging members. The spacing between the bridging members around each central mandrel is non-equiangular. The positions of the bridging members and orifices in each hole may be identical or may be mirrored between adjacent holes. The method also includes an optional step of orienting the circularly closed geometric tube prior to the forming step, and a step of verifying the predetermined position of the non-equiangular welds after the hydroforming step. The part may be an A-pillar roof rail of a vehicle structure.

[0010] In another form, a method for forming a part is provided, the method comprising extruding material through a die and forming a circularly closed geometric tube from the material. The die includes an aperture having a central mandrel, a plurality of bridging members, and corresponding plurality of orifices between the bridging members. The spacing between the bridging members around the central mandrel is non-equiangular. The circularly closed geometric tube has a non-equiangular weld after exiting the die.

[0011] In another embodiment, an apparatus is provided for forming a circularly closed geometric tube, the apparatus comprising a mold. The mold has a circular aperture, a central mandrel disposed within the circular aperture, a plurality of bridging members, and corresponding plurality of orifices between the bridging members. The bridging members and orifices extend about the central mandrel. The spacing between the bridging members about the mandrel is non-equiangular.

[0012] Among other features, the mold includes a plurality of circular holes; a plurality of central spindles disposed within each of the circular holes; and bridging members and corresponding sets of orifices between the bridging members, each set of bridging members and orifices extending about each of the central spindles. The spacing between the bridging members and orifices of each of the plurality of circular holes may be the same or may be mirrored between adjacent circular holes. The apparatus may also include forming equipment adapted to receive the circular closed geometric tube for further processing.

[0013] Other applicable areas will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0014] This disclosure will be more fully understood in light of the detailed description and accompanying drawings, in which:

[0015] Figure 1 This is an exploded perspective view of an orifice extrusion apparatus including a die, constructed in accordance with the teachings of this disclosure;

[0016] Figure 2 It is based on the teachings of this publication. Figure 1 A side sectional view of an orifice extrusion device;

[0017] Figure 3 It is by Figure 1 A front sectional view of the tube extruded by the die, showing four welds at non-equiangular locations;

[0018] Figure 4 This is a schematic diagram showing a pipe with three welds at non-equiangular locations;

[0019] Figure 5 It is a description of Figure 1 A schematic diagram of the material / billet extruded into a tube by the die of an orifice extrusion device;

[0020] Figure 6 It is a description of Figure 1 A schematic diagram of a modified die for an orifice extrusion device extruding material / bills into two tubes, the two tubes having welds at the same location;

[0021] Figure 7 It is a description of Figure 1 A schematic diagram of a modified die for an orifice extrusion device extruding material / bills into two tubes, the two tubes having welds in mirror positions;

[0022] Figure 8 It is by Figure 1 A schematic diagram of a modified die for an orifice extrusion apparatus extruding material / bills into two tubes, the two tubes having welds with identical non-equiangular spacing but offset from each other at an angle; and

[0023] Figure 9 This is a schematic diagram of a rotary stretch bending tool, which is used to make a material... Figure 1 The tube extruded by the die of the orifice extrusion equipment is bent.

[0024] The corresponding reference numerals throughout the various views of the accompanying drawings indicate the corresponding parts. Detailed Implementation

[0025] The following description is merely exemplary in nature and is not intended to limit this disclosure, its application, or its uses.

[0026] refer to Figure 1The orifice extrusion apparatus 8 constructed according to the teachings of this disclosure includes a die 10 and a container 12 therein housing the die 10. The die 10 is configured to form a circularly closed geometric tube (such as a tube 44) from a material 40, which in one form may be a preform. The die 10 includes a plate 18, a central mandrel 22, and a cap 30. The container 12 includes a receiving space 14 having an inner surface 16. The plate 18, the central mandrel 22, and the cap 30 are disposed in the receiving space 14 of the container 12. The plate 18 and the cap 30 have outer surfaces abutting against the inner surface 16 of the container 12. The central mandrel 22 is connected to the plate 18 and extends axially from the plate 18 in a downstream direction.

[0027] Plate 18 includes an outer ring 20 disposed abutting against an inner surface 16, a plurality of bridging members 24 extending radially in the outer ring 20, and a plurality of orifices 26 disposed between the plurality of bridging members 24. The plurality of bridging members 24 connect the outer ring 20 to a central spindle 22 and are spaced apart radially at non-equiangular intervals. Orifices 26 are disposed between adjacent bridging members 24. Figure 1 The illustrative example shows four bridging elements 24 and four orifices 26. It should be understood that any number of bridging elements 24 and orifices 26 can be formed in the plate 18.

[0028] A lid 30 is disposed in the receiving space 14 of the container 12 and downstream of the plate 18. The lid 30 defines an opening 32 and defines an annular or circular hole 33 therebetween around a central axis 22, through which the extrusion tube 44 exits the mold 10.

[0029] refer to Figure 2 The orifice extrusion apparatus 8 also includes a punch 54 disposed upstream of the die 10, the container 12, and the billet 40. To extrude the billet 40 into a tube 44, the billet 40 is inserted into the container 12 and extruded by the punch 54. The billet 40 is, in one form, an aluminum alloy billet and is extruded through the die 10 under high temperature and pressure. In the first stage, the billet 40 is extruded through orifices 26 of the plate 18 to form multiple tube segments 42 (e.g., ...). Figure 1 (As shown). In the second stage, as the blank 40 and the tube section 42 continue to be pressed by the stamping rod 54, the tube section 42 reconverges and then passes through the annular hole 33 between the central mandrel 22 and the cover 30 to form a closed circular tube 44 due to the pressure and heat within the mold 10.

[0030] Figure 2The dashed arrow F in the figure indicates the flow direction of the aluminum material, which is initially in the form of a billet 40, is divided into multiple flows at plate 18, reconverges in front of the annular hole 33 between the central mandrel 22 and the cover 30, and then exits the mold 10 in the form of a closed tube 44. The reconvergence of the tube segments 42 forms a weld 48, in which the tube segments 42 are joined together. The weld 48 extends longitudinally along the length of the tube 44. The weld 48 is not a weld in the conventional sense, but rather a joint of the tube segments 42 joined together by pressure and heat.

[0031] Return to reference Figure 1 Optionally, the central mandrel 22 may include a marking element 28, which may be a raised or recessed structural feature on the outer surface of the central mandrel 22. When the tube segment 42 reconvers in front of the annular hole 33 between the central mandrel 22 and the cap 30, the marking element 28 causes a point 52 to form along the length of the tube 44. The marking element 28 forms the point 52 in the aluminum tube almost simultaneously with the formation of the weld 48 and is positioned in a fixed position relative to the weld 48. The point 52 is a positioning feature that allows a person or machine to determine the weld position. A method for forming an extruded tube with a positioning feature is disclosed in US 9,533,343 entitled “Aluminum Orifice Extruded Tube with Positioning Feature,” which is collectively assigned to the assignee of this application, and the contents of which are incorporated herein by reference in their entirety.

[0032] refer to Figure 3 The tube 44 extruded by the die 10 of the orifice extrusion device 8 is shown as a circular tube having a plurality of welds 48 extending longitudinally along the length of the tube 44 and completely passing through the sidewall 46 of the tube 44. It should be understood that the welds 48 are present, but may not be visible in the extruded tube 44. The number of welds 48 corresponds to the number of orifices 26 and the number of bridging members 24 of the plate 18. The bridging members 24 are arranged with non-equiangular spacing therebetween. Thus, the welds 48 are located in non-equiangular positions, such that the sidewall 46 of the tube 44 is divided by the welds 48 into a plurality of curved sections of different sizes.

[0033] exist Figure 3 In the illustrative example, four welds 48 are formed in the tube 44 to divide the tube 44 into four curved portions, including a first curved portion 70 with an arc angle greater than 90°, a second curved portion 71 with an arc angle less than 90°, and two third curved portions 74 with arc angles of 90°. One of the curved portions is enlarged by shifting one weld 48 away from its angular position. The increased angular length of the first curved portion 70 in the tube 44 will help to position the weld 48 away from areas of high stress / strain during subsequent forming processes, which will be described in more detail below.

[0034] refer to Figure 4The mold 10 may alternatively include a plate 18 having three bridging members 24 and three orifices 26. Therefore, the tube 44 extruded by the mold 10 may include three welds 48 dividing the tube 44 into a first bend 80, a second bend 82, and a third bend 84. One of the welds 48 may be offset from its isoangular position A by a predetermined angle θ, such that the first bend 80 has an arc angle greater than 120° (i.e., 120° + θ°), the second bend 82 has an arc angle less than 120° (i.e., 120° - θ°), and the third bend 84 has an arc angle of 120°. The first bend 80 is larger than the second bend 82 and the third bend 84.

[0035] refer to Figures 5 to 7 The die 10 can be configured to extrude one extrusion tube at a time. Figure 5 ) or two extrusion tubes ( Figure 6 and Figure 7 (or more extrusion tubes.) Figure 5 As shown, the die 10 of the orifice extrusion device 8 may include an orifice 33 (e.g., Figure 2 As shown, the die 10 is used to extrude an extrusion tube 44 from a blank 40. The plate 18 of the die 10 is configured to include three bridging members 24 and three orifices 26, thereby producing an extrusion tube with three welds 48. Similarly, the bridging members 24 are spaced non-equiangularly, such that the welds 48 are located in non-equiangular positions.

[0036] refer to Figure 6 Alternatively, the die 10 of the orifice extrusion apparatus 8 can be configured to include two orifices 33 for simultaneously extruding two extrusion tubes 44 from a preform 40. Each orifice 33 corresponds to a central mandrel 22, a plurality of bridging elements 24, and a corresponding plurality of orifices 26 between the bridging elements 24. The plurality of bridging elements 24 and orifices 26 for the two orifices 33 can be formed in a plate 18. In other words, the die 10 includes a plate 18 having two sets of bridging elements 24 and orifices 26, two central mandrels 22, and a cap 30 defining two openings 32. The two central mandrels 22 are inserted into the two openings 32 of the cap 30 to define the two orifices 33. The spacing of the bridging elements 24 around each central mandrel 22 is non-equiangular. The bridging elements 24 can be arranged such that the spacing between the bridging elements 24 and the orifices 26 of each orifice 33 is the same. Therefore, the two extrusion tubes 44 extruded from the two orifices 33 of the same die 10 have welds 48 at the same interval. Although Figure 6 Three welds 48 are shown, but it should be understood that each set of bridging elements 24 and orifices 26 of each hole 33 may have any number of bridging elements 24 and orifices 26 to form a pipe with a corresponding number of welds 48.

[0037] Although not shown in the accompanying drawings, it should be understood that the mold can be configured to have a plurality of central spindles 22; a plate 18 including a plurality of sets of bridging elements 24 and orifices 26 surrounding the plurality of central spindles 22; and a cover 30 defining a plurality of holes 33 together with the plurality of central spindles 22. The number of sets of bridging elements 24 and orifices 26, and the number of central spindles 22, can be one, two, or more.

[0038] refer to Figure 7 Similar to Figure 6 The die 10 of the orifice extrusion apparatus can be configured to include two orifices 33 for simultaneously extruding two extrusion tubes 44 from a blank 40. However, the bridging members 24 and orifices 26 of the plate 18 can be arranged such that the spacing between the bridging members 24 and orifices 26 of each orifice 33 is mirrored between adjacent orifices 33. Thus, the two extrusion tubes 44 extruded from the two orifices 33 have welds 48 at the mirrored interval as they exit the die 10 of the orifice extrusion apparatus 8.

[0039] refer to Figure 8 In another form of this disclosure, the bridging members 24 of the two holes 33 and the orifices 26 of the plate 18 are arranged with the same non-equiangular spacing, but the bridging members 24 and orifices 26 of one hole 33 are offset at an angle relative to the bridging members 24 and orifices 26 of the other hole 33, such that the welds of the resulting two extruded tubes are offset at an angle relative to each other.

[0040] After the tube 44 is extruded through the die 10 of the orifice extrusion equipment, the tube 44 undergoes a hydroforming process to form a finished part with the desired final shape. Prior to hydroforming, the tube 44 may undergo a series of processes such as bending, preforming, and cutting.

[0041] refer to Figure 9 Prior to the hydroforming process, the tube 44 can be bent using a rotary stretch bending tool 62 to roughly shape the extruded tube 44 into an intermediate shape, so that the tube 44 will be assembled into a mold for the hydroforming process. The weld 48 of the tube 44 has slightly different material properties than the rest of the tube 44, which can cause early strain positioning during subsequent hydroforming operations, where the tube 44 may fail when it expands or bends circumferentially.

[0042] To reduce the likelihood of pipe 44 rupturing at or near weld 48, pipe 44 can be appropriately oriented at a predetermined location in the rotary tensile bending tool 62, such that the non-equiangular weld 48 is positioned away from high-risk areas. Examples of high-risk areas include corners of hydroforming dies, hydroforming die dividing lines, areas of localized circumferential expansion, and any areas where cracks have been experimentally observed. High-risk areas can be predicted in advance through finite element simulation of the forming process sequence. The non-equiangular spacing between welds provides greater flexibility in locating welds away from high-risk areas. Compared to conventional equiangular weld spacing, non-equiangular spacing typically results in a significant reduction in failure risk due to early strain localization at or near the weld.

[0043] After tube 44 is bent, it can undergo a hydroforming process to form a final part with a complex shape, such as an A-pillar roof longitudinal beam for vehicle structures. During the hydroforming process, weld 48 is appropriately positioned away from the high-strain regions of the final part to be formed. After the hydroforming process, the predetermined location of the non-equilateral fillet weld can be verified.

[0044] In the method of forming a part according to this disclosure, an aluminum billet is extruded through a die to form a circular closed geometric tube. In one form, the die includes a hole having a central mandrel, a plurality of bridging members, and corresponding plurality of orifices between the bridging members. In another form, the die includes a plurality of holes, each including a central mandrel, a plurality of bridging members, and corresponding plurality of orifices between the bridging members. The spacing of the bridging members around the central mandrel is non-equiangular. Therefore, the circular closed geometric tube formed from the billet has non-equiangular welds after exiting the die. The tube 44 is extruded in a continuous operation. The tube 44 can be stretched after extrusion. The extruded structure tube 44 is cut to a desired length. The tube 44 is then aligned in a bending tool 62 and oriented to place a weld 48 in a predetermined position where the tube is subjected to less stress / strain during subsequent forming steps. Finally, the bent tube is subjected to a hydroforming process to form a final part with a desired shape. The finished part may be an A-pillar roof rail for a vehicle structure.

[0045] It should be noted that this disclosure is not limited to the embodiments described and illustrated by example. Many variations have been described, and much of this is knowledgeable to those skilled in the art. These and other variations, as well as any substitutions of technical equivalents, may be added to the description and drawings without departing from the scope of this disclosure and this patent.

[0046] According to the present invention, a method for forming a part is provided: extruding material through a die comprising a hole having a central mandrel, a plurality of bridging members, and corresponding plurality of orifices between the bridging members, wherein the spacing between the bridging members around the central mandrel is non-equiangular; forming a circularly closed geometric tube from the material, the circularly closed geometric tube having a non-equiangular weld after exiting the die; shaping the circularly closed geometric tube into an intermediate shape; and hydroforming the intermediate shape into the part.

[0047] According to one embodiment, the mold includes a plurality of holes, each hole having a central mandrel, a plurality of bridging members, and a corresponding plurality of orifices between the bridging members, wherein the spacing of the bridging members around each central mandrel is non-equiangular.

[0048] According to one embodiment, the invention is further characterized in that the spacing between the bridging member and the orifice of each of the holes is the same.

[0049] According to one embodiment, the spacing between the bridging element and the orifice of each of the holes is mirrored between adjacent holes.

[0050] According to one embodiment, the invention is further characterized by the step of orienting the circular closed geometric tube such that the non-equiangular weld is in a predetermined position before the forming step.

[0051] According to one embodiment, the invention is further characterized by a step of verifying the predetermined position of the non-equilateral fillet weld after the hydroforming step.

[0052] According to one embodiment, the step of forming the circular closed geometric tube includes bending.

[0053] According to one embodiment, the invention is further characterized by a step of preforming the intermediate shape after bending and before hydroforming.

[0054] According to one embodiment, the material is an aluminum alloy.

[0055] According to the present invention, a method for forming a part is provided: extruding material through a die comprising a hole having a central mandrel, a plurality of bridging members and corresponding plurality of orifices between the bridging members, wherein the spacing of the bridging members around the mandrel is non-equiangular; forming a circularly closed geometric tube from the material, the circularly closed geometric tube having a non-equiangular weld after exiting the die and reconverging.

[0056] According to one embodiment, the invention is further characterized by the following steps: bending the circular closed geometric tube into an intermediate shape; preforming the intermediate shape; and hydroforming the intermediate shape into the part.

[0057] According to one embodiment, the invention is further characterized by the step of orienting the circular closed geometric tube such that the non-equiangular weld is in a predetermined position before the bending step.

[0058] According to one embodiment, a part is formed.

[0059] According to the present invention, an apparatus for forming a circular closed geometric tube is provided: a mold having: a circular hole; a central spindle disposed within the circular hole; and a plurality of bridging members and corresponding plurality of orifices between the bridging members, the bridging members and orifices extending around the central spindle, wherein the spacing of the bridging members around the spindle is non-equiangular.

[0060] According to one embodiment, the invention is further characterized by a plurality of circular holes; a plurality of central spindles disposed in each of the circular holes; and a corresponding set of orifices between the bridging member and the bridging member, each set of the bridging member and the orifices extending around each of the central spindles.

[0061] According to one embodiment, the spacing between the bridging element and the orifice of each of the plurality of circular holes is the same.

[0062] According to one embodiment, the spacing between the bridging element and the orifice of each of the plurality of circular holes is mirrored between adjacent circular holes.

[0063] According to one embodiment, the invention is further characterized in that the circular closed geometric tube has a non-equiangular weld.

[0064] According to one embodiment, the invention is further characterized by a forming apparatus adapted to accommodate the circular closed geometric tube for further processing.

[0065] According to one embodiment, the invention is further characterized in that the part has a non-equilateral fillet weld.

Claims

1. A method of forming a part, comprising: Material is extruded through a die, the die comprising a hole having a central mandrel, a plurality of bridging members, and a plurality of corresponding orifices between the bridging members, wherein the spacing between the bridging members around the central mandrel is non-equiangular; as well as A circular closed geometric tube is formed from the material, and the circular closed geometric tube has a non-equiangular weld after exiting the mold; The circular closed geometric tube is shaped into an intermediate shape using a rotary stretching and bending tool. The circular closed geometric tube is appropriately oriented at a predetermined position in the rotary stretching and bending tool, so that the non-equilateral weld is set away from the high-risk area. as well as The intermediate shape is hydroformed into the part.

2. The method of claim 1, further comprising preforming the intermediate shape prior to hydroforming.

3. The method of any of the preceding claims, wherein the mold comprises a plurality of holes, each hole having a central mandrel, a plurality of bridging members, and a corresponding plurality of orifices between the bridging members, wherein the spacing of the bridging members around each of the central mandrels is non-equiangular.

4. The method of claim 3, wherein the spacing between the bridging element and the orifice of each of the holes is the same.

5. The method of claim 3, wherein the spacing between the bridging element and the orifice of each of the holes is mirrored between adjacent holes.

6. The method of claim 1, further comprising the step of orienting the circular closed geometric tube such that the non-equiangular weld is in a predetermined position prior to the forming step.

7. The method of claim 6, further comprising the step of verifying the predetermined position of the non-equilateral fillet weld after the forming step.

8. The method of claim 1, wherein the step of shaping the circular closed geometric tube includes bending.

9. The method of claim 8, further comprising the step of preforming the intermediate shape after bending and before hydroforming.

10. The method of claim 1, wherein the material is an aluminum alloy.

11. An apparatus for forming a circular closed geometric tube, comprising: The mold has: Round hole; A central spindle is set inside the circular hole; and Multiple bridging elements and corresponding multiple orifices between the bridging elements, the bridging elements and orifices extending around the central mandrel. The spacing of the bridging members surrounding the mandrel is non-equiangular; A circular closed geometric tube is formed from the material, the circular closed geometric tube having a non-equiangular weld after exiting the mold; It also includes a rotary stretching and bending tool, which is used to shape the circular closed geometric tube into an intermediate shape, wherein the circular closed geometric tube is appropriately oriented at a predetermined position in the rotary stretching and bending tool, so that the non-equilateral weld is set away from the high-risk area; as well as The intermediate shape is hydroformed into a part.

12. The apparatus of claim 11, wherein the mold comprises: Multiple round holes; Multiple central spindles are disposed within each of the circular holes; and A bridging element and a corresponding set of orifices between the bridging elements, each set of the bridging elements and orifices extending about each of the central mandrels.

13. The device of claim 12, wherein the spacing between the bridging member and the orifice of each of the plurality of circular holes is the same.

14. The device of claim 12, wherein the spacing between the bridging element and the orifice of each of the plurality of circular holes is mirrored between adjacent circular holes.

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