JP4473705B2 - Hydroform processing method, hydroform molded article and structure - Google Patents

Description

  The present invention is used for the manufacture of exhaust system parts, suspension system parts, body parts, etc. for automobiles. After putting a metal pipe into a mold and clamping the mold, the internal pressure and the axial direction of the pipe are in the pipe. The present invention relates to a hydroform processing method, a molded product, and a structure that are molded into a predetermined shape by applying a pressing force.

  In recent years, hydroform technology has been attracting attention in the automobile field as one of the means for reducing costs and reducing weight by reducing the number of parts, and it has been applied to actual vehicles in Japan since 1999. Since then, the number of applicable parts for hydroforming has increased year by year, and the market size has greatly expanded.

  On the other hand, from the viewpoint of weight reduction, it is desirable to thicken the portions necessary for strength and rigidity and to thin the portions that are not so. However, since hydroform is generally formed from a single metal tube, the thickness of the molded product is almost uniform throughout. Although the plate thickness changes due to pipe expansion or axial push, it is difficult to deliberately build the appropriate plate thickness distribution as described above. Therefore, recently, hydroforming using tailored tubes such as Patent Document 1 and Patent Document 2 has been studied as one means for solving these problems. The tailored tube is a metal tube in which a plurality of metal tubes having different plate thicknesses and materials are combined in advance, and when this is used, a relatively appropriate plate thickness distribution can be obtained.

  The tailored tube manufacturing method includes a method in which metal tubes having different plate thicknesses and materials are joined in the tube axis direction, and a metal plate (so-called tailored blank) in which metal plates having different plate thicknesses and materials are joined in advance is tubular. There are two types of methods. However, the number of types of materials constituted by any method is about two to three. The reason is that as the number of types increases, problems such as welding accuracy and thermal deformation occur, and the cost increases.

Therefore, as an effective method for the above-mentioned problem, there is a method of hydroforming by fitting a reinforcing tube 6 into a place to be reinforced in advance as in Patent Document 1 (described above) or Patent Document 3 (FIG. 1). By this method, it is possible to obtain a component with a finely divided strength arrangement. Further, as a method of locally strengthening a necessary portion, there is a method of welding the patch 2 from the outside as shown in FIG. 2 (FIG. 2).
Japanese Patent Laid-Open No. 2001-321843 JP 2002-53069 A JP 2001-334316 A

  The above-mentioned tailored tube hydroform and hydroform fitted with a reinforcing steel pipe also have a problem that it is very difficult to search for processing conditions during molding. In the first place, the most difficult thing in hydroforming is the balance between the internal pressure inside the pipe (hereinafter referred to as internal pressure) and the amount of pushing in the axial direction of the pipe (hereinafter referred to as axial pushing amount). FIG. 3 shows an example of a load path at the time of hydroforming in a normal uniform plate thickness / uniform material pipe (hereinafter referred to as a single pipe). In this way, even a single pipe shows a complicated load path, and not only the final internal pressure and the axial push amount but also the path along the way is very important. For example, if the internal pressure in the middle is too high ((a) in the figure), the tube may rupture in the middle of molding, or wrinkles may remain if the pressure in the middle is too low ((c) in the same figure). This proper load path naturally depends on the tube thickness and material characteristics. Therefore, in the case of tailored tubes having different plate thicknesses and materials, the load path becomes more difficult. For example, if molding is performed with a load path suitable for the material on the high strength side, the pressure is too high for the material on the low strength side, so that it tends to burst in the middle. On the other hand, if molding is performed with a load path suitable for the material on the low strength side, bursting in the middle can be prevented, but buckling is likely to occur because the material on the high strength side is axially pressed in a state where it hardly swells. Therefore, it is very difficult to derive the hydroforming processing conditions for tailored tubes, and highly skilled techniques are required. Also, if molding is impossible even if skilled techniques are required, it is necessary to make changes such as reducing the product expansion ratio or reducing the strength difference between materials. However, the advantages of the original tailored tube and hydroform cannot be fully utilized, and the effect of weight reduction will be diminished. Further, even when there is a reinforcing pipe, the same problem as the problem with the tailored tube occurs because the reinforcing pipe needs to be expanded simultaneously with the raw pipe.

  In addition, the method of welding the patch is flexible in the sense that it can reinforce a favorite part, but since a welding process is required, the load is heavy both in terms of equipment and efficiency, and the cost is high. In addition, in the case of a component that requires fatigue characteristics, it is desirable in terms of product reliability that the number of welded portions is as small as possible.

  Also, a problem when applying a hydroformed molded product to an automobile part is joining with other members. This is because spot welding, which is often used normally, is difficult to apply to a hydroformed molded product having a closed cross section. Therefore, it is desired to join by laser welding or the like, but in that case, there is a problem that new equipment investment is required.

  As described above, the present invention provides a hydroform processing method that enables appropriate reinforcement only at an appropriate location in order to maximize the weight reduction effect of the hydroform, and a hydroform processed component molded by the processing method. The purpose is to provide. Moreover, it aims at providing the processing method of the hydroform component with a flange which was difficult conventionally, and the said hydroform component and structure which applied it.

In order to solve the problem, the gist of the present invention is as follows.
(1) The metal tube, which is larger than the outer periphery of the metal tube and wound in part in an axially opened metal sheath tube, is fixed to a mold, and an internal pressure and a pressing force in the axial direction of the tube or internal pressure are applied to the metal tube. Hydroform processing method characterized by loading.
(2) The hydroforming method as described in (1) above, wherein an inner end portion of the metal sheath tube in contact with the metal tube is previously deleted.
(3) The hydroforming method as described in (1) or (2) above, wherein the corner portion of the metal sheath tube that contacts the metal tube is deleted in advance.
(4) The hydroforming method according to any one of (1) to (3), wherein a metal sheath tube whose cross-sectional shape is changed in the axial direction is wound around the metal tube.
(5) Any one of the above (1) to (4), wherein a metal sheath tube with a flange portion or a metal cylinder bent to form a post-processing flange portion is wound around the metal tube. The hydroforming method according to item.
(6) The hydroforming method according to any one of (1) to (5), wherein a bent metal plate is wound around a metal tube instead of the metal sheath tube.
(7) The hydroform processing method according to any one of (1) to (6), wherein a metal sheath tube or a metal plate having a spiral shape of one or more rounds is wound around the metal tube.
(8) A hydroforming part in which a metal pipe is subjected to hydroforming by applying an internal pressure and a pressing force in the axial direction of the pipe axis, or an internal pressure, and a part of the metal pipe is expanded. Part or all of the product is wound with a metal sheath tube having an opening in the axial direction.
(9) A hydroforming component in which a metal tube is subjected to hydroforming by applying an internal pressure and a pressing force in the axial direction of the tube, or an internal pressure, and a part of the metal tube is expanded , and is open in the axial direction; A hydrofoam molded product , wherein a metal sheath tube with a flange portion is fixed by being wound around a part or the entire outer periphery of the expanded portion of the metal tube.
(10) A metal structure which is integrally welded with the hydroform molded product of (9).

  According to the present invention, it is possible to mold a part having a more appropriate strength and thickness distribution, which could not be molded by a conventional tailored tube hydrofoam or a hydrofoam using a reinforcing tube having a closed cross section. Moreover, since a welding process is unnecessary, a highly reliable part can be obtained at a lower cost than the conventional patch welding method. Furthermore, spot welding with other parts, which has been difficult in the past, is also possible. These effects can further reduce the weight of automobiles and contribute to the prevention of global warming.

  FIG. 4 shows a reinforcing member (hereinafter referred to as a sheath tube) having an open cross-sectional shape in which a metal tube (hereinafter referred to as a basic tube) 5 to be hydroformed has a slit (also referred to as an opening) 10 in the tube axis direction. ) Is an example of hydroforming when the tube is expanded to a rectangular cross section using 9. The details of the present invention will be described using this example.

First, the basic tube 5 and the sheath tube 9 are prepared. The sheath tube 9 has an inner diameter larger than the outer diameter of the basic tube 5 and has an open cross section (so-called C-shaped cross section) having a slit portion 10 on the circumference.
A sheath tube 9 is inserted outside the prepared basic tube 5 as shown in FIG. At that time, the position of the sheath tube 9 in the tube axis direction is set at a location where reinforcement is desired in the molded part. Further, since the sheath tube 9 has an open cross section, it may not reach the entire circumference after molding. In that case, it is necessary to consider the circumferential position of the slit portion 10 of the sheath tube 9, and the slit portion 10 is set in advance to a location where reinforcement is not required so that the sheath tube 9 exists at the location where reinforcement is desired after molding. Keep it.
The basic tube 5 and the sheath tube 9 combined as described above are set on the lower mold 4b of the hydroform, and the upper mold 4a is closed.

  Thereafter, pressure is applied to the inner surface of the basic pipe 5 and simultaneously so-called hydroforming is performed in which both pipe ends are axially pushed. The basic tube 5 is formed into a shape 5 a along the inner surface of the mold 4 by hydroforming. At the same time, the sheath tube 9 is sandwiched between the basic tube 5 a and the mold 4 and formed into a shape 9 a along the mold 4. Since the sheath tube 9 has an open cross section, it hardly extends in the circumferential direction, and is formed only by bending deformation in the plate thickness direction. Therefore, compared with the basic pipe 5, the internal pressure required for the deformation can be reduced. That is, it becomes possible to mold under almost the same processing conditions as the hydroforming processing conditions in the case of only the basic pipe 5. This point is an advantage over the conventional method. In the method using the conventional closed cross-section sheath tube 9, the closed cross-section sheath tube 9 itself needs to extend in the circumferential direction. A large internal pressure is required. Then, the hydroforming conditions for a single pipe cannot be used as they are, and in some cases, proper hydroforming conditions may not be obtained.

  However, the sheath tube 9 of the present invention may come off after molding depending on the position where it is attached. At the position in the circumferential direction of the sheath tube 9a as in (a-1) and (a-2) in FIG. In order to prevent this, it is necessary that the sheath tube 9a exists as far as the sheath tube 9a cannot be removed as shown in FIGS. However, it is not always necessary to lengthen the circumferential length of the sheath tube 9a. If the shape of the part is devised, it is possible to prevent the sheath tube 9a from coming off even if the circumferential length of the sheath tube 9a is short. For example, it is possible to prevent the sheath tube 9a from being detached after molding if the parts are cross-sectioned as shown in (c-1), (c-2), and (c-3). Further, such a cross section may extend over the entire length of the sheath tube 9a, or may be a part of the tube axis direction. (D-1) is an example in which the recessed portion 11 is in the shape of a groove in the entire length of the sheath tube 9a, and (d-2) is an example in which the recessed portion 11 is only partially recessed. In either case, the sheath tube 9a is prevented from coming off.

  Moreover, when the plate | board thickness of the sheath pipe 9a is thick, as shown to (a) of FIG. 6, the thinning of the basic pipe 5a becomes remarkable in the location 13 which hits the edge part 12 inside the sheath pipe, and in hydroform There is a risk of cracking. Therefore, the end 12 on the inner side of the sheath tube in the circumferential direction and the tube axis direction is cut at an angle as shown in FIG. 5B, or an end face such as providing an R inside as shown in FIG. It is desirable to apply processing. Similarly, removing the corner portion 14 of the sheath tube as shown in FIG. 2 (c-1) obliquely (not shown) or attaching an R is effective in preventing cracking during hydroforming of the part. is there.

Next, a method for manufacturing the sheath tube 9 will be described.
The sheath tube 9 does not need to be manufactured by the method of inserting the slit 10 in the tube axis direction of the metal tube 15 as shown in FIG. 7 (a-1), and the metal plate 16 as shown in FIG. 7 (a-2). May be manufactured by rounding. Further, the cross section is not required to be a perfect circle, and may be a cross sectional shape obtained by simply bending the metal plate as shown in FIGS. Thus, in the sheath tube 9 in this invention, there exists also an advantage that manufacturing cost can be reduced by simplifying the manufacturing method.

  Further, the shape of the sheath tube 9 does not need to be constant in the axial direction, and the shape of the cross-sectional shape may be changed in the axial direction as in the example of FIG. If this advantage is utilized to the maximum, the maximum effect can be exerted on the merit of weight reduction of parts.

  Moreover, you may apply the sheath tube 9a not only to one place but to multiple places. FIG. 9A is an example applied to two places in the circumferential direction in the same cross section, and FIG. 9B is an example applied to three places in the pipe axis direction. Each sheath tube 9a need not have the same material, the same plate thickness, and the same shape, and an appropriate sheath tube 9a can be employed at a necessary location, which is very effective from the viewpoint of weight reduction. . In order to achieve the same effect with a tailored tube, a finely divided tailored tube is required. Naturally, it is very difficult to manufacture the tailored tube and hydroform processing. Further, as shown in FIG. 9 (b), it is an advantage of the present invention that the place to be applied can be easily applied not only to the straight portion of the basic pipe 5a but also to the curved portion.

  Moreover, when it is necessary to make the sheath tube 9a exist over the entire circumference after the hydroforming, as shown in FIG. 10 (a-1), the sheath tube adapted to the circumferential length of the molded sheath tube 9a. 9 may be wound around the basic tube 5 in a spiral shape. If it is hydroformed, a cross section reinforced over the entire circumference as shown in FIG. When further applied, the sheath tube 9a is doubled only in a part of the cross section, as shown in FIG.

Next, an example will be described in which a hydroformed component provided with a flange is formed using a sheath tube 18 having a T-shaped cross section. As shown in (a-1) of FIG. 11, the sheath tube 18 having a shape obtained by rounding a part of the T shape is set in the lower mold 4 b. At that time, the portion 19 corresponding to the flange is placed in the gap of the mold, and the upper mold 4a is closed as it is (a-2). After that, when hydroforming is performed, a hydroform part having a flange portion, that is, a metal sheath pipe 18 having a flange portion 21 is fixed by being wound around a part of the outside of the expanded portion 5a of the metal pipe 5. A foam molded article is obtained (a-3). The above is an example using the T-shaped sheath tube 18, but as shown in FIG. 5B-1, when the metal plate 20 is formed by bending a simple plate material, the metal plate 20 is clamped. You may provide the flange part 21 by crushing a part of (b-2). Thereafter, if hydroforming is performed in the same manner, a hydroformed part with a flange similar to (a) can be obtained (b-3). The flanged hydrofoam component obtained in this way can be easily joined to the other member 22 by welding of the peripheral portion, spot welding or the like.
In addition, in FIG. 11, although the example in which a metal sheath tube is wound around a part of the outer side of the expanded portion of the metal tube is shown, as shown in FIG. It can fix more firmly by winding said metal sheath tube.

  As described above, according to the present invention, the degree of freedom of the sheath tube 9 to be reinforced and the applied basic tube 5 is high as compared with the conventional method, and the lightening effect can be maximized. In addition, if the present invention is applied, welding that is difficult with conventional hydroform parts can be easily applied.

Examples of the present invention are shown below.
The shape for expanding the pipe into a rectangular cross section as shown in FIG. As the basic pipe, a steel pipe made of STKM11A having an outer diameter of 63.5 mm, a plate thickness of 2.3 mm, and a total length of 490 mm was used. As the sheath tube, a material having an outer diameter of 82.6 mm, a plate thickness of 2.0 mm, and a total length of 80 mm and a material obtained by slitting a steel tube of STKM11A was used (slit width = 10 mm). Hydroform processing conditions are as shown in FIG. The processing conditions are the same as the molding conditions in the case of only a basic pipe without a sheath pipe.

  FIG. 12C shows a photograph of the molding result. It can be seen from the photograph that a hydrofoam component having a central portion reinforced with a sheath tube can be obtained. In addition, since this part was able to be molded under the same conditions as in the case of only the basic pipe, the search for hydroforming processing conditions did not require any trouble. For comparison, when the same molding is performed using a steel pipe without slits made of the same material as the sheath pipe, it is hardly expanded at the place where the sheath pipe is fitted, but it bursts at other places and cannot be molded. there were.

Explanatory drawing of the hydroform processing method at the time of fitting the conventional pipe for reinforcement of a closed cross section is shown. Explanatory drawing of the method of reinforcing by welding the conventional patch is shown. Indicates the type of processing failure caused by the hydroform load path. The explanatory view of the hydroforming processing method which fits and reinforces the sheath pipe of the open section by the example of the present invention is shown. Explanatory drawing of the suitable fitting method of the sheath pipe of this invention is shown. 3 shows the appropriate shape of the sheath tube end of the present invention. The manufacturing method and cross-sectional shape of the sheath pipe of this invention are shown. The kind of sheath tube shape of this invention is shown. The attachment position of the sheath pipe of this invention is shown. The sheath tube at the time of winding in the spiral form of this invention is shown. The processing method of the hydroform part with a flange of this invention, and the hydrofoam molded article and structure processed by the said method are shown. The Example of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydroform molded product 2 ... Reinforcing patch 3 ... Welding part 4 ... Hydroform metal mold 4a .. Hydroform upper metal mold 4b .. Hydroform lower metal mold 5 ... Hydro Formed metal pipe (basic pipe)
5a ・ ・ Metal tube after hydroforming (basic tube)
6 ... Reinforcing tube material 7 ... Axial punch 7a ... Axial punch (left side)
7b ・ ・ Axial push punch (right side)
8 ... Water filling port 9 ... Reinforcing member with open cross section (sheath tube)
9a ·· Sheath tube after hydride 10 ·· Slit portion (opening) of sheath tube
11 .. Recessed portion 12 for fixing the sheath tube.. Inner end portion 13 of the sheath tube.. Base tube portion 14 that contacts the end portion of the sheath tube after hydroforming... Corner portion 15 of the sheath tube. Pipe 16 ·· Metal plate 17 for sheath tube · Hole 18 opened in sheath tube · Structural material 18a for flange · Flange sheath tube 19 after hydroforming · · Flange portion 20 of flange sheath tube · · Bending Processed metal plate 20a, metal plate 21 after hydroforming, flange portion 22 formed by being sandwiched between dies, other member 23 to be joined by spot welding, spot welding electrode 24, spot welded portion

Claims (10)

  The metal tube, which is larger than the outer periphery of the metal tube and is partially wound with a metal sheath tube that is opened in the axial direction, is fixed to a mold, and an internal pressure and a pressing force in the axial direction of the tube axis or an internal pressure are applied to the metal tube. Hydroform processing method characterized by the above.   The hydroform processing method according to claim 1, wherein an inner end portion of the metal sheath tube in contact with the metal tube is deleted in advance.   The hydroform processing method according to claim 1 or 2, wherein a corner portion of the metal sheath tube in contact with the metal tube is previously deleted.   The hydroforming method according to any one of claims 1 to 3, wherein a metal sheath tube having a cross-sectional shape changing in the axial direction is wound around the metal tube.   The hydrometallurgy according to any one of claims 1 to 4, wherein a metal sheath tube having a flange portion or a metal sheath tube bent to form a flange portion after processing is wound around the metal tube. Form processing method.   The hydroforming method according to any one of claims 1 to 5, wherein a bent metal plate is wound around the metal tube instead of the metal sheath tube.   The hydroform processing method according to any one of claims 1 to 6, wherein a metal sheath tube or a metal plate having a spiral shape of one or more rounds is wound around the metal tube. A hydroforming component in which a metal tube is subjected to hydroforming by applying an internal pressure and a pressing force in the axial direction of the tube, or an internal pressure, and a part of the metal tube is expanded, or a part of the expanded portion of the metal tube or A hydroform molded product characterized in that the whole is wound with a metal sheath tube having an opening in the axial direction. Pushing force of the pressure and axial direction of the tube to the metal tube, or a portion of the metal tube subjected to hydroforming to load an internal pressure a hydroforming parts by tube expansion, open in the axial direction, and the flange portion A hydroform molded product , wherein the attached metal sheath tube is fixed by being wound around a part or the entire circumference of the expanded portion of the metal tube.   A metal structure which is welded integrally with the hydroform molded product according to claim 9.

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