JP2006255750A - Metallic structure member and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a metallic structure member having excellent strength at a reasonable manufacturing cost. <P>SOLUTION: This method compeises: a stage for forming a preformed body 20 having a part where work hardening on the basis of the impartation of shearing strain is caused from a tubular base stock; and a stage for hydrostatically forming formed goods which are applied to the metallic structural member by bulging and deforming the preformed body 20 by the impartation of the liquid pressure to the inside of it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal structural member and a method for manufacturing the same.

  For example, a metal structural member is manufactured by applying hydraulic forming to a tubular material.

  However, the tubular material has a problem that the strength of the member is relatively lowered because the plate thickness is reduced due to tensile deformation during the hydraulic forming. On the other hand, it is possible to apply a high-strength material in order to ensure the strength of the member, but the high-strength material is expensive and causes a problem that the manufacturing cost increases.

  The present invention has been made to solve the problems associated with the prior art, and an object of the present invention is to provide a metal structural member having good strength and manufacturing cost, and a manufacturing method thereof.

In order to achieve the object, the invention according to claim 1 provides:
A method for producing a metal structural member having a hollow cross-section,
A step for forming a preform from a tubular material having a site where work hardening based on application of shear strain is caused; and
A metal structure characterized by having a step for forming a hydroformed product to be applied to the metal structural member by applying a hydraulic pressure to the preformed body so as to bulge and deform. It is a manufacturing method of a member.

The invention according to claim 9 for achieving the object is as follows.
It is a metal structure member manufactured by the manufacturing method of the metal structure member of any one of Claims 1-8.

  According to the first aspect of the present invention, work hardening based on application of shear strain is caused to the tubular material to form a preform. The application of shear strain does not cause a reduction in plate thickness in the preform. Therefore, it is possible to ensure the strength of the hydroformed product applied to the metal structural member without using an expensive tubular material with high strength. That is, the manufacturing method of the metal structural member which has favorable intensity | strength and manufacturing cost can be provided.

  According to the ninth aspect of the present invention, a hydraulically molded product having a sufficient strength can be manufactured without applying an expensive tubular material having a high strength. Therefore, the metal structural member to which the hydroformed product is applied has good strength and manufacturing cost. That is, a metal structural member having good strength and manufacturing cost can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view for explaining a metal structural member according to an embodiment of the present invention, and FIG. 2 is a perspective view for explaining a material of the metal structural member of FIG.

  The metal structural member 40 has a side wall having a rectangular cross section, and is applied to, for example, an automobile structural member having a hollow cross section (closed cross section structure) such as a member or a pillar.

  The metal structural member 40 includes a preforming step for forming a preform from a tube material (tubular material) 10 that has a portion where work hardening based on the application of shear strain is caused, and the interior of the preform. In addition, it is manufactured by a manufacturing method having a hydraulic forming step for forming a hydraulic molded product applied to a metal structural member by applying a hydraulic pressure to cause deformation. Reference numerals 44 and 45 denote a horizontal side wall surface and a vertical side wall surface of the metal structural member 40.

  The tubular material 10 has a substantially circular cross section in the direction orthogonal to the extending direction (axial direction) X of the central axis S1 of the tubular material 10, and a hollow extruded material or a drawn material is applied. It is also possible to apply a hollow member formed by bending the plate material such as roll forming and joining the end surfaces of the plate material by butt laser welding or the like. Although the raw material of the pipe material 10 will not be specifically limited if it has appropriate intensity | strength, For example, they are steel, an aluminum alloy, or a magnesium alloy.

  A method for manufacturing the metal structural member 40 will be described in detail. 3 is a perspective view for explaining end processing in the preforming step, FIG. 4 is a perspective view for explaining shear deformation processing in the preforming step, and FIG. 5 is a shear deformation processing apparatus according to FIG. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a perspective view for explaining a preform formed from the preforming step.

  In the pre-forming step, shear strain is applied in a direction perpendicular to the extending direction X of the central axis S1 of the tube material 10 by subjecting the tube material 10 to shear deformation.

  The shear deformation processing apparatus shown in FIG. 5 and FIG. 6 is capable of rotating the clamp portions 110 and 120 for restraining the end portions 12 and 16 in the longitudinal direction of the tube material 10 and the clamp portions 110 and 120 so as to be rotatable and close to and away from each other. And a driving device (not shown) for driving. The clamp parts 110 and 120 have a plurality of protrusions 115 and 125 arranged symmetrically with respect to the central axis S2 of the clamp parts 110 and 120.

  On the other hand, the end portions 12 and 16 of the tube material 10 are formed with uneven portions 13 and 17 by, for example, machining (see FIG. 3). The shape of the concavo-convex portions 13 and 17 corresponds to the shape and arrangement of the protrusions 115 and 125 of the clamp portions 110 and 120, and the alignment between the central axis S2 of the clamp portions 110 and 120 and the central axis S1 of the tube material 10; In addition, the end portions 12 and 16 of the tube material 10 are easily restrained. In addition, it is preferable to make the protrusions 115 and 125 versatile by configuring the protrusions 115 and 125 so that they can be fixed even if the circumferential shape of the tube material 10 is changed, so that the replacement of the clamp portions 110 and 120 is unnecessary.

  In the pre-forming step, for example, the steel tubular material 10 is set in a shear deformation processing apparatus, and the concave and convex portions 13 and 17 of the tubular material 10 come into contact with the protrusions 115 and 125 of the clamp portions 110 and 120. The clamp portions 110 and 120 are driven so as to be close to each other along the extending direction Y of the central axis S2, and are completely in close contact with the tube material 10 disposed in the middle.

  When the alignment between the center axis S2 of the clamp portions 110 and 120 and the center axis S1 of the tube material 10 and the restraint of the end portions 12 and 16 of the tube material 10 are achieved, the drive device is in a state where the clamp portion 120 is fixed. Thus, the clamp part 110 is rotated, for example, 23 degrees to cause torsional deformation with respect to the central axis S1 of the tube material 10. That is, the pipe material 10 is subjected to shear deformation processing for imparting shear strain that causes work hardening. Torsional deformation is preferable because shear deformation can be applied to the entire tube material 10.

  The rotation of the clamp part 110 generates wrinkles in the tube material 10, and the tube material 10 contracts in the extending direction X. Therefore, in conjunction with the contraction of the tube material 10, the clamp portions 110 and 120 are brought close to each other, and the adhesion between the clamp portions 110 and 120 and the tube material 10 is maintained.

  When the wrinkles 28 are slightly generated, the rotation of the clamp part 110 is stopped, the clamp parts 110 and 120 are separated from each other, and the preform 20 is taken out (see FIG. 4). Then, as for the preforming body 20, the uneven | corrugated | grooved parts 23 and 27 currently formed in the edge parts 22 and 26 are cut off (refer FIG. 7).

  For example, the shear deformation caused by the torsional deformation can apply a shear strain of 1% or more to the entire surface of the tube material 10, and can apply a plastic strain of 7% or more to the wrinkle portion. The plate thickness of the preform 20 has almost no change from the plate thickness of the tube material 10 and is not accompanied by a reduction in plate thickness, so that work hardening can be effectively used.

  The torsional deformation with respect to the central axis S1 of the tube material 10 can also be caused by rotating the clamp portions 110 and 120 in different directions. It is also preferable to amplify the shear strain by repeating the rotation of the clamp unit 110 a plurality of times while changing the rotation direction.

  The restraints of the end portions 12 and 16 of the tube material 10 are not limited to the mechanical means described above, and a joining means such as welding can also be used. The amount of rotation (angle) of the clamp unit 110 can be adjusted as necessary so as not to cause wrinkles.

  A hydraulic molding apparatus applied to the hydraulic molding process will be described. 8 is a cross-sectional view for explaining a hydraulic forming apparatus according to a hydraulic forming step, FIG. 9 is a cross-sectional view for explaining an auxiliary die of the hydraulic forming apparatus of FIG. 8, and FIG. It is sectional drawing for demonstrating the side type | mold of this hydraulic forming apparatus.

  The hydraulic molding apparatus 200 includes a hydraulic pressure supply unit and a molding die. The hydraulic pressure supply means has nozzles 210 and 220 which are inserted into the openings of the end portions 22 and 26 of the preform 20 and seal the end portions 22 and 26.

  The nozzle 210 is connected to, for example, a pressure generator using a pressure increasing cylinder or a pipe 225 extending from a forming medium source. The pipe 225 is connected to a flow path 215 that extends inside the nozzle 210. The channel 215 has an opening 216 at the tip of the nozzle 210. The forming medium is introduced into the preform 20 from the opening 216 via the pipe 225 and the flow path 215. The forming medium is, for example, water.

  The mold has an upper mold 230, a lower mold 235, side molds 240 and 245, and auxiliary molds 250, 255, 260 and 265. The upper mold 230 and the lower mold 235 are arranged so as to be close to and away from each other, and have a cavity corresponding to the side wall surface 44 in the horizontal direction of the metal structural member 40. The side molds 240 and 245 are disposed so as to be close to and away from each other, and have cavities corresponding to the side wall surfaces 45 in the vertical direction of the metal structural member 40. The upper mold 230, the lower mold 235, and the side molds 240 and 245 constitute a substantially rectangular cavity corresponding to the side wall of the metal structural member 40 as a whole.

  The auxiliary dies 250 and 255 have semicircular concave portions that take into consideration the thickness of the preform 20 and the outer peripheral shape of the nozzle 210, are arranged so as to be close to and away from each other, and are preformed with the nozzle 220 inserted therein. It is used to press the end 22 of the body 20 from above and below to ensure the sealing between the nozzle 210 and the end 22. The auxiliary dies 260 and 265 have semicircular recesses that take into account the thickness of the preform 20 and the outer peripheral shape of the nozzle 220, are arranged so as to be close to and away from each other, and the preform with the nozzle 220 inserted therein. It is used to press the end portion 26 of the body 20 from above and below to ensure the sealing between the nozzle 220 and the end portion 26.

  The hydroforming process will be described in detail with reference to FIGS. FIG. 11 is a cross-sectional view for explaining a set of preforms in the hydroforming process, FIG. 12 is a cross-sectional view for explaining nozzle insertion following FIG. 11, and FIG. 13 follows FIG. FIG. 14 is a cross-sectional view related to the line XIV-XIV in FIG. 13, and FIG. 15 is a cross-sectional view for explaining the press by the side mold, following FIG. 13. 16 is a cross-sectional view taken along line XVI-XVI in FIG. 15, FIG. 17 is a cross-sectional view for explaining pressing by the upper mold and the lower mold following FIG. 15, and FIG. 18 is a line XVIII-XVIII in FIG. FIG. 19 is a perspective view for explaining a hydroformed product.

  First, the preform 20 that has a portion where work hardening based on the application of shear strain has been caused and is carried in from the preforming step is set on the lower mold 235 (FIG. 11). Then, the nozzles 210 and 220 are inserted into the openings of the end portions 22 and 26 of the preform 20 (FIG. 12).

  When the auxiliary molds 250 and 255 are close to each other, the end portion 22 of the preform 20 is pressed in the vertical direction so that the inner surface of the opening and the outer periphery of the nozzle 210 are in close contact with each other. Similarly, the inner surface of the end portion 26 and the outer periphery of the nozzle 220 are brought into close contact (FIGS. 13 and 14).

  Thereby, the confidentiality of the preform 20 is ensured. At this time, since the openings of the end portions 22 and 26 of the preform 20 are forcibly deformed, the accuracy of roundness is reduced during shear deformation processing (torsional deformation) in the preforming process. Even so, the hydraulic forming is sufficiently possible.

  Thereafter, the molding medium is introduced into the preform 20 through the opening 216 at the tip of the nozzle 210 via the pipe 225 and the flow path 215, and a hydraulic pressure is applied to the preform 20.

  The hydraulic pressure rises and the preform 20 starts to bulge, and the side molds 240 and 245 come close to each other and press the preform 20 from the side (FIGS. 15 and 16).

  Subsequently, the upper mold 230 and the lower mold 235 gradually approach each other and press the preform 20 from above and below (FIGS. 17 and 18). The hydraulic pressure inside the preform 20 is controlled so as not to buckle by pressing with the upper mold 230, the lower mold 235 and the side molds 240 and 245.

  At this time, almost no compressive strain is applied to the horizontal side wall surface 24 of the preform 20, but compressive strain is applied to the vertical side wall surface 25. Further, the wrinkle 28 of the preform 20 disappears due to the bulging deformation based on the pressure by the upper mold 230, the lower mold 235 and the side molds 240, 245 and the internal hydraulic pressure, and by the bending back deformation of the wrinkle portion, Greater strain is applied compared to other parts.

  When the hydraulic pressure reaches a predetermined final value, the supply of the forming medium is stopped and held for a predetermined time. Then, after releasing the pressure, the mold is opened, and the hydroformed product 30 is taken out (FIG. 19). Since the end portions 32 and 36 of the hydroformed product 30 are substantially cylindrical, the metal structural member 40 (see FIG. 1) is obtained by trimming.

  As described above, the preform 20 that is the material of the hydroformed product 30 is subjected to shear strain on the entire surface thereof without reducing the plate thickness, and plastic strain is applied to the wrinkled portion. As a result, work hardening is caused. In the hydroforming process, the compressive strain is applied to the vertical side wall surface 35, and the reinforced portion 39 in which the wrinkle portion is bent back is deformed in a larger strain than other portions. Is granted. Therefore, the metal structural member 40 to which the hydroformed product 30 is applied has a sufficient strength and a high manufacturing cost without having to use a high-strength and expensive tubular material.

  The horizontal side wall surface 34 of the hydroformed product 30 is hardly given compressive strain in the hydroforming step, but is given strain in the pre-molding step. That is, according to the present embodiment, it is possible to improve the strength by work-hardening a portion that could not be given distortion in the conventional manufacturing method.

  Wrinkles generated by shear deformation (torsional deformation) in the preforming process can be eliminated in the hydraulic forming process. Further, since the shear deformation process is not accompanied by a reduction in the plate thickness, the conditions for the shear deformation process can be determined without considering the occurrence of molding failure due to necking based on the reduction in the plate thickness in the hydraulic forming step. Therefore, the degree of freedom of control conditions for shear deformation processing is large, and for example, large shear strain can be applied by not suppressing the occurrence of wrinkles.

  When a metal material having strain aging, such as steel or an aluminum alloy, is used as the material of the tube material 10, it has a step for applying a strain aging treatment to the preform 20 or the hydroformed product 30. Is also preferable. The strain aging treatment is a treatment for improving the strength by, for example, heat treatment at 170 ° C. for 20 minutes.

  FIG. 20 is a perspective view for explaining the crushing test, and FIG. 21 is a chart for explaining the creation conditions of the test pieces (Examples 1 to 4 and Comparative Example 1) applied to the crushing test.

  In the crushing test, the striker 330 was dropped and given an impact to the test body (Examples 1 to 4 and Comparative Example 1) 310 joined to the base plate 320 by welding, and the energy absorption amount at a displacement of 50 mm was evaluated.

  The test piece 310 is a hollow tube having a rectangular cross section of 75 mm × 75 mm, and the length of the central axis in the extending direction is 200 mm. One end 312 of the test piece 310 is fixed to the base plate 320 via the welded portion 340, and the other end 316 faces the striker 330. The weight and dropping speed of the striker 330 are 500 kg and 10 m / second, and the lower surface 335 that collides with the end portion 316 of the test piece 310 forms a horizontal and flat surface.

  In Examples 1 to 4 and Comparative Example 1, the materials are the same, and a strain-aging steel material having a plate thickness of 2.0 mm and a tensile strength of 590 MPa is applied. The increase in the proof stress after performing heat treatment at 170 ° C. for 20 minutes as a strain aging treatment after applying 2% of uniaxial tension in the steel material is about 20 to 30 MPa.

  Example 1 is rotated by 22.5 degrees in the torsional deformation in the preforming process, and after the hydroforming process, the end of the hydroformed product is cut so that the length of the central axis in the extending direction Is adjusted to 200 mm. Example 2 is different from Example 1 in that in the torsional deformation in the preforming process, it is further rotated 22.5 degrees after rotating 22.5 degrees.

  Example 3 is different from Example 1 in that heat treatment is performed at 170 ° C. for 20 minutes as strain aging treatment after the hydroforming process. Example 4 differs from Example 2 in that a heat treatment of 170 ° C. × 20 minutes is performed as a strain aging treatment.

  Comparative Example 1 is different from Example 1 in that it has not undergone the preforming step.

  FIG. 22 is a graph for explaining the test result of the crush test.

  The energy absorption amount of Examples 1 to 4 is about 7400J to about 7900J. The energy absorption amount of the comparative example is about 6600J. Therefore, it was confirmed that Examples 1 to 4 had the same amount of absorbed energy and improved strength as compared with the comparative example, while having the same shape as the comparative example.

  The energy absorption amounts of Example 1 and Example 2 are about 7400 J and about 7700 J, and the energy absorption amounts of Example 3 and Example 4 are about 7600 J and about 7900 J. Therefore, Examples 2 and 4 have better absorbed energy amounts than Examples 1 and 3, respectively, and in the torsional deformation in the preforming process, the shear direction is repeated several times while changing the rotation direction. It was confirmed that the distortion was amplified.

  Examples 3 and 4 each had a better absorbed energy amount than Examples 1 and 2, and it was confirmed that the strength was improved by the strain aging treatment.

  As described above, according to the present embodiment, the work hardening based on the application of shear strain is caused to the tubular material, and the preform is formed. The application of shear strain does not cause a reduction in plate thickness in the preform. Therefore, it is possible to ensure the strength of the hydroformed product applied to the metal structural member without using an expensive tubular material with high strength. That is, the manufacturing method of the metal structural member which has favorable intensity | strength and manufacturing cost can be provided.

  In addition, according to the present embodiment, a hydraulically molded product with a ensured strength can be manufactured without applying an expensive tubular material with high strength. Therefore, the metal structural member to which the hydroformed product is applied has good strength and manufacturing cost. That is, a metal structural member having good strength and manufacturing cost can be provided.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.

  For example, the cross section of the metal structural member is not limited to a rectangular shape, and other shapes can be applied. Moreover, the shaping | molding die applied to hydraulic molding is not limited to the form which has an upper mold | type, a lower mold | type, a side mold | type, and an auxiliary mold | type.

It is a perspective view for demonstrating the metal structural member which concerns on embodiment of this invention. It is a perspective view for demonstrating the raw material of the metal structural member of FIG. It is a perspective view for demonstrating the edge part process of the preforming process in the manufacturing method which concerns on embodiment of this invention. It is a perspective view for demonstrating the shear deformation process of the preforming process in the manufacturing method which concerns on embodiment of this invention. It is sectional drawing for demonstrating the shear deformation processing apparatus which concerns on FIG. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is a perspective view for demonstrating the preforming body produced from a preforming process. It is sectional drawing for demonstrating the hydraulic forming apparatus which concerns on the hydraulic forming process following a preforming process. It is sectional drawing for demonstrating the auxiliary | assistant type | mold of the hydraulic forming apparatus of FIG. It is sectional drawing for demonstrating the side type | mold of the hydraulic forming apparatus of FIG. It is sectional drawing for demonstrating the set of the preforming body in a hydraulic forming process. FIG. 12 is a cross-sectional view for explaining nozzle insertion following FIG. 11. It is sectional drawing for demonstrating the press by an auxiliary | assistant type | mold following FIG. It is sectional drawing regarding line XIV-XIV of FIG. It is sectional drawing for demonstrating the press by a side type | mold following FIG. FIG. 16 is a cross-sectional view taken along line XVI-XVI in FIG. 15. It is sectional drawing for demonstrating the press by an upper mold | type and a lower mold | type following FIG. FIG. 18 is a sectional view taken along line XVIII-XVIII in FIG. 17. It is a perspective view for demonstrating a hydraulic pressure molded product. It is a perspective view for demonstrating a crush test. It is a graph for demonstrating the creation conditions of the test piece (Examples 1-4 and the comparative example 1) applied to the crushing test. It is a graph for demonstrating the test result of a crush test.

Explanation of symbols

10. Tube material (tubular material),
12, 16, ... end,
13, 17, ... Uneven portion,
20. Pre-formed body,
22, 26 ... the end,
23, 27 .. Uneven portion,
24, 25 .. side wall surface,
28 .. Wrinkles,
30 ・ ・ Hydraulic molded products,
32, 36 .. end,
34, 35 .. side wall surface,
39. Strengthening part,
40 .. Metal structural members,
44, 45 .. side wall surface,
110, 120 .. clamp part,
115, 125 ... projections
200 ・ ・ Hydraulic molding equipment,
210, 220 .. Nozzle,
215 .. flow path,
216 .. opening,
225 ... Piping
230 .. Upper mold,
235 ... Lower mold,
240, 245 ... Lateral type,
250, 255, 260, 265 ... auxiliary type,
310 .. Test piece,
312 316 end
320 .. Base plate,
330 ... striker,
335 .. lower surface,
340..welded part,
S1, S2, .. central axis,
X, Y ... Extension direction.

Claims (11)

A method for producing a metal structural member having a hollow cross-section,
A step for forming a preform from a tubular material having a site where work hardening based on application of shear strain is caused; and
A metal structure characterized by having a step for forming a hydroformed product to be applied to the metal structural member by applying a hydraulic pressure to the preformed body so as to bulge and deform. Manufacturing method of member.   The method for manufacturing a metal structural member according to claim 1, wherein the tubular material has a substantially circular cross section with respect to a direction orthogonal to an extending direction of a central axis of the tubular material.   In the step of forming the preform, a shear strain is imparted in a direction perpendicular to the extending direction of the central axis of the tubular material by subjecting the tubular material to a shear deformation process. The manufacturing method of the metal structural member of Claim 2.   The shear deformation process is performed by constraining both ends in the longitudinal direction of the tubular material and causing torsional deformation with respect to the central axis of the tubular material to the tubular material. 3. A method for producing a metal structural member according to 3.   The method of manufacturing a metal structural member according to claim 4, wherein the torsional deformation generates wrinkles.   6. The method for producing a metal structural member according to claim 5, wherein the wrinkles are eliminated by bulging deformation of the preform in a step for forming a hydroformed product. The tubular material is made of a metal material having strain aging,
The method for manufacturing a metal structural member according to any one of claims 1 to 6, further comprising a step for performing a strain aging treatment on the preform or the hydroformed product.   The method for manufacturing a metal structural member according to claim 7, wherein the metal material is steel, an aluminum alloy, or a magnesium alloy.   A metal structural member manufactured by the method for manufacturing a metal structural member according to claim 1.   The metal structural member according to claim 9, wherein the metal structural member is applied to a structural member for an automobile.   The metal structural member according to claim 10, wherein the automobile structural member is a pillar or a member.

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