JP4492184B2 - Hydroforming method and preform of hydroformed product - Google Patents

Description

  The present invention relates to a hydroforming method capable of detecting peeling of a joint portion during hydroforming and a preform of a hydroformed product.

  For example, vehicle body structural members of automobiles such as side members have a hollow structure in order to improve shock absorption, and reinforcing rib members that divide the hollow cross section are disposed inside to supplement the strength.

  Such a structural member may be formed by extruding an aluminum alloy. However, since it is difficult to set and arrange reinforcing rib members in the longitudinal direction and the degree of freedom in shape and layout is low, recently, It is formed by pressure molding (see Patent Document 1 below).

  In the proposal of Patent Document 1, a honeycomb core material is provided between an upper plate material and a lower plate material, and the honeycomb core material is partially joined, and then plastically deformed by hydraulic bulging in a mold. The material is molded.

  However, in the case where the intermediate material is joined between the upper surface plate material and the lower surface plate material and placed in the mold and subjected to hydraulic molding, both the materials are swelled into a predetermined shape. However, there is a problem in that the joining state of the internal intermediate material cannot be visually observed from the outside, and the quality of the hydroformed product cannot be confirmed during the hydroforming.

In particular, when the bonding state of the reinforcing rib material to the outer plate material greatly affects the reinforcing strength, such as a car body structural member of an automobile, confirmation of this bonding state is extremely important. It is not possible to examine the internal structure by opening the outer plate material. Further, for example, even if X-rays are irradiated to examine individual internal structures, it is disadvantageous in terms of equipment and work efficiency.
Japanese Patent Laid-Open No. 11-254067 (see FIG. 1, abstract)

  The present invention solves the problems associated with the above prior art and provides a hydraulic molding method and a preform of a hydraulic molded product that can very easily detect peeling of the joint inside the hydraulic molded product. For the purpose.

In the hydroforming method according to the present invention for achieving the above object, at least one inner plate material is disposed between at least a pair of outer plate materials, and the edges of the outer plate material are overlapped and joined together. When a preform is formed by partially joining a plate material, the preform is placed in a mold, and a liquid pressure is supplied to the inside of the preform to bulge and form the inner plate and the inner plate. When the junction of the plate material is peeled, the inner and outer portions of the outer sheet is communicated, the joint has a peeling weakening portion to facilitate communication inside and outside of the outer plate, the peeling weakened portion The through plate is formed in advance in the outer plate material in the region of the joining portion, and the outer plate material and the inner plate material are welded and joined in a state where the through hole is closed by the inner plate material .

In addition, the preform of the hydraulic molded product according to the present invention that achieves the above object is a preform of the hydraulic molded product that is bulging and molded by the hydraulic pressure supplied to the interior while being placed in the mold. Body,
At least a pair of outer plate members having outer peripheral edge portions that are overlapped and bonded, at least one inner plate member arranged between the outer plate members, and a bonded portion formed by partially bonding the outer plate member and the inner plate member When the joint between the outer plate material and the inner plate material is peeled off when supplying the hydraulic pressure to the inside and bulging and molding, the inner and outer sides of the outer plate material are in a communication state, and the joint portion is There is a peeling weakening portion that facilitates communication between the inside and outside of the outer plate material, and the peeling weakening portion forms a through hole in advance in the outer plate material in the region of the joint portion, and the through hole is used as the inner plate material. The outer plate material and the inner plate material are welded and joined in a state of being closed by the above .

In the present invention configured as described above, when the preform formed in a state in which the outer plate material and the inner plate material are joined is subjected to hydraulic expansion molding in the mold, the outer plate material is removed when the joint portion of the outer plate material and the inner plate material is detached. Since the inside and outside communicate with each other and the internal hydraulic pressure leaks to the outside of the outer plate material, it is possible to detect the disconnection of the joint portion very easily. Further, even when the hydroformed product is carried out of the mold, it can be confirmed by directly observing the disconnection of the joint portion from the outside. Therefore, when producing a hydraulic molded product by a flow operation, if the detection result is immediately fed back to the operation start unit, it is possible to prevent a quality defect of the hydraulic molded product and take quick action. Then, a through hole is formed in the outer plate material in the region of the joint portion in advance, and the outer plate material and the inner plate material are welded and joined in a state where the through hole is closed by the inner plate material. When a peeling weakened portion that facilitates communication is formed in the joint, a communication state is immediately generated by the peeling, and the joint peeling can be detected at an early stage of molding.

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

  1 is a plan view showing a preform according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1, FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. FIG. 3 is a cross-sectional view showing a hydroformed product after bulging.

  For example, as shown in FIG. 4, a side member that is a vehicle body structural member of an automobile has a hollow shaft-shaped member 1 having a substantially rectangular cross section, and supports a corner portion inside the shaft-shaped member 1. A hollow hydroformed product composed of reinforcing rib members 2 provided in a cross shape is used. In this hydroformed product, a preform formed by joining the peripheral portions of the pair of outer plate members 3 and 4 and the peripheral portions of the inner plate members 5 and 6 and the outer plate members 3 and 4 in advance in a mold. It swells and forms by pressure.

  As shown in FIGS. 1 and 2, the preformed body 10 includes two inner plate members 5 as reinforcing rib members 2 in a shaft-like member 1 composed of two relatively long outer plate members 3 and 4. 6 are provided, and end portions of the inner plate members 5 and 6 and predetermined positions of the outer plate members 3 and 4 are partially joined by welding.

  More specifically, the outer plate members 3 and 4 supply a hydraulic pressure to the inside, a reinforcing portion 7a reinforced by the inner plate members 5 and 6, a non-reinforcing portion 7b in which the inner plate members 5 and 6 are not disposed. A hydraulic pressure supply portion 7c is provided, and the peripheral portion is overlapped and welded to maintain the internal airtightness to form a joint portion S.

  As shown in FIG. 1, the hydraulic pressure supply part 7c has a hydraulic pressure inlet 8 and an opening 9, and the hydraulic pressure inlet 8 communicates with the reinforcing part 7a via a non-reinforcing part 7b.

  As shown in FIG. 3, the reinforcing portions 7 a of the outer plate members 3 and 4 are formed by bonding the both side ends of the inner plate members 5 and 6 whose center portions are bonded from one end to the other end in the axial direction to the outer plate members 3 and 4. Although formed, the inner plate members 5 and 6 and the outer plate members 3 and 4 are joined as follows.

  FIG. 5 is a cross-sectional view taken along lines 5A-5A, 5B-5B, 5C-5C, and 5D-5D in FIG. 6, and (A) shows a joined state between the lower inner plate material and the lower outer plate material, (B) is a bonding state between the inner plate materials, (C) is a bonding state between the upper inner plate material and the upper outer plate material, (D) is a bonding state around the outer plate material, and FIGS. ) Is a plan view sequentially showing a reinforcing part forming step of a preform.

  As shown in FIG. 5A, first, the lower inner plate 6 is placed at the center of the reinforcing portion 7a of the lower outer plate 4 to join the inner plates 5 and 6 and the outer plates 3 and 4. As shown in FIG. 6 (A), both side edge portions of the lower inner plate material 6 are welded to the lower outer plate material 4 from the upper side of the inner plate material 5 from one end to the other end in the axial direction. This welding method is preferably plasma welding with good directivity and deep penetration.

  Next, as shown in FIG. 5B, the upper inner plate material 5 is placed on the lower inner plate material 6, and the central portion of the lower inner plate material 6 and the central portion of the upper inner plate material 5 are placed. As shown in FIG. 6 (B), plasma welding is performed over the entire length in the axial direction from above the inner plate material 5 so as to be parallel to the weld lines of the respective side end portions of the inner plate material 6 and the outer plate material 4. To do.

  Then, as shown in FIG. 5 (C), the upper outer plate material 3 is superposed on the upper inner plate material 5, and as shown in FIG. 6 (C), the vicinity of both end portions of the inner plate material 5 and the outer plate material. 3 are joined by plasma welding from above the outer plate material 3.

  Finally, as shown in FIGS. 5D and 6D, when the outer peripheral edge portions of the outer plate materials 3 and 4 are sealed by plasma welding over the entire circumference, the preformed body 10 shown in FIG. 3 is obtained. .

  Here, in the preformed body 10 according to the present embodiment, the region R (the predetermined width M and the predetermined length surrounded by the one-dot chain line in FIG. 1) of the joint portion S between the both side ends of the inner plate material 5 and the outer plate material 3. The peeling weakening portion Y is formed in a region having a thickness L (hereinafter also referred to as a bonding region R). The peeling weakening portion Y is communicated between the inside and outside of the outer plate material 3 by peeling before the normal peeling of the joining portion S when the bonding between the inner plate material 5 and the outer plate material 3 is peeled off at the time of hydroforming described later. This is the part that allows the liquid supplied at the time of hydraulic forming to leak to the outside and to detect the peeling of the joint quickly.

  7A and 7B show an exfoliation weakening portion according to the present embodiment. FIG. 7A is an enlarged cross-sectional view of the exfoliation weakening portion before welding, and FIG. 7B is an enlarged cross-sectional view of the exfoliation weakening portion after welding.

  Specifically, as shown in FIG. 7A, the peeling weakening portion Y of the present embodiment is a joint region R between the outer plate materials 3 and 4 and the inner plate materials 5 and 6 (both sides of the inner plate materials 5 and 6). Opening holes O are formed in the outer plate members 3 and 4 corresponding to the end portions), and plasma welding is performed with the inner plate members 5 and 6 backed so as to close the through holes.

When the outer plate materials 3 and 4 with holes and the inner plate materials 5 and 6 are welded, as shown by a broken line hatch in FIG. 7B, meat around the through hole of the lower outer plate material 4 and a part of the inner plate material 6 There melted, cause gentle concave water reservoir, which block the hole O and solidified, thin part of the relatively thick t _s integrated with the inner sheet 5, 6 and the outer sheet 3 and 4 are formed The

  This thin-walled portion is weak in strength because it is thin when a force is applied to peel off the inner plate members 5 and 6 from the outer plate members 3 and 4 at the time of hydraulic forming, and normal welding in which no other through hole O is opened. It becomes easier to peel off than the part. However, although the peeling weakening portion Y is weak against peeling, the flange portion F formed at the end portions of the inner plate members 5 and 6 will be described in detail later even when a pressing force is applied from the outside. Since the peeling weakening portion Y is reinforced, it is possible to firmly counter the pressure applied by the outer plate materials 3 and 4.

  It is preferable that the through holes O formed as the peeling weakening portions Y are provided scattered throughout the joining region R. In this way, it is possible to know at a point where in the joining region R the peeling has occurred with a high positional accuracy, and in the case of hydroforming during the flow operation, this data is used as an initial step. By providing feedback, it is possible to prevent the subsequent product from being peeled off and to produce a product of good quality.

  The through holes O may be provided in the joining region R of the outer plate materials 3 and 4 with a predetermined length between each other. In this way, the peeling position detection accuracy enough to be scattered all over the above-mentioned area cannot be obtained, but since the number of through holes O may be small, manufacturing becomes easy and large through holes are formed. It can be easily peeled off.

When the through holes O are formed in the joining region R of the outer plate members 3 and 4 at a predetermined interval, the size and position of the through holes O may be any as long as the communication state is formed. good, according to experiments, the inner diameter d of the hole O is the thickness t ₁ the same level of the outer plate 3 and 4, it may be preferable to 2-3 times the thickness t ₁ be larger It turns out.

In the experiment, a plate for an outer plate material having a thickness of 2 mm was prepared. The first plate has a through hole O with an inner diameter d of 2 mm, the second plate has a through hole O with an inner diameter d of 3 mm, and the third plate has a through hole O with an inner diameter d of 4 mm. Established. The pitch p of the through holes O of each plate is the same as or larger than the inner diameter d of the through holes O. A plate (2 mm) thick for the inner plate material is arranged on the back surface of the outer plate material plate so as to close the through hole O, and plasma welding is performed along the established through hole O to weaken the peeling. Part Y was formed. Thereafter, an experiment was conducted to determine whether or not both the outer plate and inner plate test plates were peeled off at a predetermined pressure. When the inner diameter d of the through hole O was 2 mm, 3 mm, or 4 mm, all Good results were obtained as the peel-off portion Y. In other words, it can be seen that the inner diameter d of the hole O may if 2-3 times the plate thickness t _1.

  In addition, although the joining of the inner plate materials 5 and 6 and the outer plate materials 3 and 4 was performed by plasma welding, it is not limited to this, for example, laser welding, slot welding, plug welding, adhesion, caulking, etc. Any means may be used as long as it penetrates and joins. Further, the entire circumference joining of the outer plate materials 3 and 4 is not limited to plasma welding, but may be any joining means that has excellent airtightness such as laser welding, arc welding, and adhesion.

  Next, a description will be given of the hydraulic molding for obtaining a hydraulic molded product from the preform 10.

  FIG. 8 is a cross-sectional view showing a hydraulic forming state of the preform according to the embodiment of the present invention, FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 8, and FIGS. FIG. 10 is a schematic cross-sectional view corresponding to FIG. 9 showing molding in the order of steps.

  As shown in FIGS. 8 and 9, the preformed body 10 is arranged between the upper die 20 and the lower die 21. When the upper die 20 and the lower die 21 are matched, the preformed product 10 is formed inside. A cavity 22 corresponding to the outer shape of the first and second concave grooves 23 corresponding to the hydraulic pressure supply portion 7c of the preform 10 are formed.

  The lower mold 21 has a nozzle portion 24 for injecting a high-pressure liquid for hydraulic molding and a hydraulic passage 25, and the nozzle portion 24 passes through the opening 9 of the preform 10 and is a space of the hydraulic pressure supply portion 7 c. Arranged inside. In addition, the hydraulic pressure supply part 7 c is equally arranged with respect to the dividing surface 26 of the upper mold 20 and the lower mold 21 at least in the hydraulic pressure inlet 8. The hydraulic pressure passage 25 is in communication with the nozzle portion 24 and a high-pressure hose 27 connected to a hydraulic pressure generator (not shown).

  First, as shown in FIG. 10A, the upper mold 20 is separated from the lower mold 21, and the preformed body 10 is inserted. Then, when the preform 20 placed on the lower mold 21 is closed, the upper mold 20 and the lower mold 21 are closed, and as shown in FIG. The nozzle portion 24 is inserted, and the side of the reinforcing portion 7a is firmly sandwiched between the upper mold 20 and the lower mold 21 as shown in FIG.

  Next, the hydraulic pressure generator is operated to supply high-pressure liquid to the nozzle portion 24 via the high-pressure hose 27 and the hydraulic pressure passage 25. The high-pressure liquid is injected into the space of the hydraulic pressure supply part 7 c of the preform 10 from the nozzle part 24, and further flows into the non-reinforcing part 7 b and the reinforcing part 7 a through the hydraulic pressure inlet 8. Since the peripheral edge portions of the outer plate materials 3 and 4 are joined over the entire circumference, the high-pressure liquid does not leak from the preformed body 10 to the outside.

  In this embodiment, since the hydraulic pressure supply part 7c is equally arrange | positioned at the division surface 24, the high pressure liquid which flowed into the non-reinforcement part 7b from the hydraulic injection port 8 bulges the non-reinforcement part 7b equally.

  The high-pressure liquid that has passed through the non-reinforcing portion 7b enters the reinforcing portion 7a and causes the outer plate members 3 and 4 to bulge and deform as shown in FIG. As the outer plate members 3 and 4 bulge and deform, the high-pressure liquid enters between the outer plate members 3 and 4 and the inner plate members 5 and 6, or between the inner plate members 5 and 6, and the inner plate members 5 and 6 are also exposed to the outside. The plate members 3 and 4 are deformed following the bulging.

  As shown in FIG. 9, the inner plate members 5 and 6 of the present embodiment are connected to the outer plate members 3 and 4, both end portions of the inner plate members 5 and 6, and the central portions of the inner plate members 5 and 6 through the joint S. Therefore, as shown in FIG. 10C, the inner plate members 5 and 6 are expanded in a so-called flat “X” shape.

  Further, when the high-pressure liquid is injected, the outer plate materials 3 and 4 are further bulged and deformed in the cavity 22 as shown in FIG. , 6 extend in a straight line like a diagonal line connecting approximately four corners of the rectangle, and expand into a substantially “X” shape.

  As a result, the molded product is a structural material having an outer tube having a rectangular cross section and a reinforcing rib member that diagonally reinforces the outer tube.

  In particular, since the inner plate members 5 and 6 are joined to the outer plate members 3 and 4 at the tip portions, when the bulge molding is performed, the tip portions are bent into an L shape and the flange portion F (FIGS. 4 and 11). Etc.) will be formed. Therefore, when an external force is applied to the outer plate members 3 and 4 in this state, the inner plate members 5 and 6 function as a reinforcing material that supports the outer plate members 3 and 4 from the inside and counters the external force. In addition, the through hole O is formed as the weakened portion Y by peeling on the outer plate materials 3 and 4, but since the flange portion F covers the through hole O from the inside, the strength against the external force may be reduced. Absent.

  FIG. 11 is a schematic cross-sectional view showing a state in which the joint portion between the inner plate member and the outer plate member has been peeled off during the hydraulic forming.

  It is assumed that the joint portion S joining the inner plate materials 5 and 6 and the outer plate materials 3 and 4 is peeled off during the hydroforming. The bonding portion S has a bonding area R having a predetermined area, and the bonding region R is provided with peeling weakening portions Y at a plurality of locations. At least one of the peeling weakening portions Y is broken.

  For example, as shown in the figure, when both ends of the inner plate material 6 are peeled off, at least one peeling weakening portion Y in the joint region R of the left and right lower corners of the outer plate materials 3 and 4 having a rectangular cross section is broken and the opening O As a result, the inside and outside of the sealed outer plate materials 3 and 4 are in communication, and the hydraulic pressure inside the outer plate materials 3 and 4 flows out to the outside. That is, the liquid that has been used for the hydraulic forming is ejected into the cavity 22 and flows out through the dividing surface 26 between the upper mold 20 and the lower mold 21. As a result, the worker can easily understand that the joint portion S between the inner plate materials 5 and 6 and the outer plate materials 3 and 4 has peeled even when the inside of the molds 20 and 21 is not visible. .

  When the occurrence of peeling is detected, the worker can stop the work and take necessary countermeasures. For example, where the peeling occurred, it becomes clear from the point of view, so if this data is fed back and the welding position or thickness is improved so that peeling does not occur, the quality defects of the hydroformed product will be prevented as much as possible. it can.

  FIG. 12 is a schematic cross-sectional view showing the peeled state of the joint when the outer plate materials are different. As shown in FIG. 12, when this embodiment is applied to a preformed body 10 having different lengths of the outer plate material 4, the outer plate material 3 and the inner plate materials 5 and 6 are not bulged and formed uniformly in the upper and lower directions. The amount of swelling of the plate material 3 is increased. When such bulging amounts are different, there is a high possibility that peeling will occur in the outer plate material 3 having a large bulging amount. Therefore, as the peeling weakening portion Y, the outer plate material 3 and the inner plate material 5 You may form in the welding area | region R. In addition, the point which covers the peeling weakening part Y with the flange part F bent in the L-shape, and raises reinforcement strength is the same as that of previous embodiment.

  As described above, in the present embodiment, when the hydraulic pressure is supplied to the inside of the preformed body 10 sandwiched between the molds to be expanded and deformed, that is, the state of the preformed body 10 cannot be observed from the outside. Even in this case, when the joint portion S between the outer plate materials 3 and 4 and the inner plate materials 5 and 6 is detached, the inner and outer sides of the outer plate materials 3 and 4 communicate with each other, and the hydraulic pressure during the hydraulic forming leaks to the outside and is bonded. The peeling will be specifically and visually notified. Moreover, when taking out from the metal mold | die after hydraulic forming, the disconnection of the junction part S can be visually observed. Therefore, when hydroforming is performed by a flow operation, if various welding conditions such as the thickness of the position material where the peeling has occurred or the thickness of the weld are fed back to the initial process, the quality of the hydroformed product will be poor. Can be prevented as much as possible, unnecessary correction work is eliminated, and workability is improved.

  In addition, if the outer plate members 3 and 4 in the bonding region R between the outer plate members 3 and 4 and the outer plate members 3 and 4 are provided with the peeling weakening portion Y, the inner plate members 5 and 6 are peeled off when the inner plate members 5 and 6 are deformed by the supplied hydraulic pressure. Since the weakened portion Y is damaged, it is possible to quickly detect peeling of the joint.

  The peeling weakening portion Y forms a through-hole in the outer plate materials 3 and 4 in the joining region R in advance and closes the through-hole with the inner plate materials 5 and 6 to solidify the melted portion generated by welding in the joining region R. If the outer plate materials 3 and 4 and the inner plate materials 5 and 6 are welded together, the peel weakening portion Y can be formed, and workability is improved.

  If the joint between the outer plate material and the inner plate material provided inside is disengaged when the hydraulic pressure is supplied to the preformed body itself, which becomes a hydraulic molded product due to hydraulic bulging deformation, the inside and outside of the outer plate material are in communication Since the peeling weakening part is provided, it is possible to detect the peeling of each individual product, improve the product quality of the hydroformed product, and to remove the peeling without using other detection members. Since it can be detected, it is advantageous in terms of cost.

  In addition, since the base portion of the inner plate material is joined to the outer plate material, it will be bent into an L shape during the hydraulic expansion molding, and the reinforcement of the outer plate material is further improved, and the resulting hydraulic molded product Has excellent strength and rigidity.

  Further, in the case of being molded normally, the inner plate material is pulled by the outer plate material that is bulged and formed through the joint between the outer plate material and the inner plate material, and extends linearly. Since it is provided on the flange portion bent in an L-shape, not on the part that stretches, the product strength is not adversely affected. In addition, if it is bent in an L shape during the hydraulic expansion molding, the reinforcement to the outer plate material is further improved, and the resulting hydraulic molding product has excellent strength and rigidity.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, in the said embodiment, although it swells and forms in a rectangle, it can shape | mold not only to this but to various shapes. In the embodiment, the outer plate material is a pair of outer plates, but in some cases, a plurality of pairs of outer plate materials can be used, and the inner plate material is not only two but also one. It may be 3 or more. In particular, when a large number of reinforcing rib members are provided radially, this is an extremely effective means for knowing which inner plate material has caused peeling.

  The peeling weakening portion of the above embodiment is formed by opening a through hole in the outer plate material in the joining region in advance and closing it by welding, but in some cases, it forms a recess in the outer plate material in the joining region. Alternatively, it may be thinly joined. In this way, the welding time is substantially shortened and workability is improved.

  Further, in the above-described embodiment, the side member which is a vehicle body structural material of the automobile is described as the hydroformed product W. However, not only this but also other structural materials such as a side sill, a front pillar, a side roof rail, a center pillar, and a bumper. May be.

  The hydraulic molding method and the preform of the hydraulic molded product according to the present invention are suitable for molding a vehicle body structural material such as a side member.

It is a top view which shows the preforming body which concerns on embodiment of this invention. It is sectional drawing which follows the 2-2 line of FIG. It is sectional drawing which follows the 3-3 line of FIG. It is sectional drawing which shows the hydraulic pressure molded product after bulging molding. 6 is a cross-sectional view taken along lines 5A-5A, 5B-5B, 5C-5C, and 5D-5D in FIG. 6, in which (A) shows a joined state between the lower inner plate material and the lower outer plate material, and (B) shows the inner side. The joint state between the plate members, (C) shows the joint state between the upper inner plate member and the upper outer plate member, and (D) shows the joint state around the outer plate member. (A)-(D) are top views which show the reinforcement part formation process of a preforming body. The peeling weak part which concerns on this embodiment is shown, (A) is an expanded sectional view of the peeling weak part before welding, (B) is an expanded sectional view of the peeling weak part after welding. It is sectional drawing which shows the hydraulic forming state of a preforming body. It is sectional drawing which follows the 9-9 line | wire of FIG. (A)-(D) are schematic sectional drawings corresponding to FIG. 9 which shows hydraulic forming in order of a process. It is a schematic sectional drawing which shows the state from which the junction part of the inner board | plate material and the outer board | plate material peeled during the hydraulic forming. It is a schematic sectional drawing which shows the peeling state of a junction part in case an outer plate | board material differs.

Explanation of symbols

3, 4 ... outer plate material,
5, 6 ... inner plate material,
10 ... preformed body,
20 ... Upper mold,
21 ... Lower mold,
22 ... cavity,
F ... Flange part,
O ... through hole,
R: Junction region,
S ... Junction,
Y ... Peeling and weakening part.

Claims (6)

At least one inner plate material is disposed between at least a pair of outer plate materials, the edges of the outer plate material are overlapped and joined, and the outer plate material and the inner plate material are partially joined to form a preform, When the preform is placed in a mold and liquid pressure is supplied to the inside of the preform to bulge and mold,
When the joint between the outer plate material and the inner plate material is peeled off, the inside and outside of the outer plate material communicate with each other.
The joint portion has a peel-weakening portion that facilitates communication between the inside and outside of the outer plate material, and the peel-weakening portion forms a through hole in advance in the outer plate material in the region of the joint portion, and A hydraulic forming method, wherein the outer plate material and the inner plate material are joined by welding in a state where the through hole is closed by the inner plate material. At least one inner plate material is disposed between at least a pair of outer plate materials, the edges of the outer plate material are overlapped and joined, and the outer plate material and the inner plate material are partially joined to form a preform, When the preform is placed in a mold and liquid pressure is supplied to the inside of the preform to bulge and mold,
When the joint between the outer plate material and the inner plate material is peeled off, the inside and outside of the outer plate material communicate with each other.
The joint has a peeling weakening portion to facilitate communication inside and outside of the outer plate, the peeling weakened portion in advance a recess in the outer plate member in the region of the joint, the concave portion A hydraulic forming method characterized in that the outer plate material and the inner plate material are welded and joined in a state where the inner plate material is closed. 3. The hydraulic forming method according to claim 1, wherein the peel-weakening portion is formed on a side of the outer plate material that has a large bulge amount in the mold. A preform of a hydroformed product that is swelled and molded by the hydraulic pressure supplied to the inside in a state of being placed in a mold,
At least a pair of outer plate members having outer peripheral edge portions that are overlapped and bonded, at least one inner plate member arranged between the outer plate members, and a bonded portion formed by partially bonding the outer plate member and the inner plate member And when forming the expansion by supplying hydraulic pressure to the inside, when the joint between the outer plate material and the inner plate material is peeled off, the inner and outer sides of the outer plate material are in a communicating state,
The joint portion has a peel-weakening portion that facilitates communication between the inside and outside of the outer plate material, and the peel-weakening portion forms a through hole in advance in the outer plate material in the region of the joint portion, and A preformed body of a hydroformed product, wherein the outer plate material and the inner plate material are welded and joined with the through hole closed with the inner plate material. A preform of a hydroformed product that is swelled and molded by the hydraulic pressure supplied to the inside in a state of being placed in a mold,
At least a pair of outer plate members having outer peripheral edge portions that are overlapped and bonded, at least one inner plate member arranged between the outer plate members, and a bonded portion formed by partially bonding the outer plate member and the inner plate member And when forming the expansion by supplying hydraulic pressure to the inside, when the joint between the outer plate material and the inner plate material is peeled off, the inner and outer sides of the outer plate material are in a communicating state,
The joint has a peeling weakening portion to facilitate communication inside and outside of the outer plate, the peeling weakened portion in advance a recess in the outer plate member in the region of the joint, the concave portion A preformed body of a hydroformed product, wherein the outer plate material and the inner plate material are welded and joined together in a state where the inner plate material is closed. 6. The pre-molding of a hydroformed product according to claim 4, wherein the peeling weakening portion is formed on a side of the outer plate material having a large bulge amount in the mold. body.

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