JP2009154556A - Joint structure of closed cross-sectional member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of a closed cross-sectional member without separately requiring an air bleeding hole, by forming a joint of a lower side member and an upper side member molded by hydroforming, as a structure also serving as the air bleeding hole. <P>SOLUTION: This joint structure of the closed cross-sectional member is provided for joining a bulkhead upper frame 3 to an upper opening part 10 so as to block up this opening part, by arranging the upper opening part 10 upward in a bulkhead lower frame 4 molded by the hydroforming, and is characterized by joining the bulkhead upper frame 3 to an overhang part 26, by arranging the overhang part 26 larger than a width dimension (w) of the bulkhead upper frame 3 in a part of the upper opening part 10 of the bulkhead lower frame 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a joint structure of a closed cross-section member that is welded and joined through a chemical conversion step such as a body frame.

Some body frames are molded by hydroforming. In this hydroforming, the pipe material set in the mold is filled with liquid, then the pipe material is pushed in the axial direction of the pipe material while increasing the liquid pressure, and the pipe material is molded following the mold. It is a construction method. According to this construction method, it is possible to cope with a continuous change in cross-sectional shape, and there is an advantage that a reduction in wall thickness due to molding is reduced.
Therefore, the closed cross-section member manufactured by such hydroforming is highly expected to be used as a vehicle body skeleton member of an automobile having a complicated cross-sectional shape.
For example, a closed cross-section member molded by hydroforming is used for a part of a skeleton member provided at the front of a vehicle body of an automobile (see, for example, Patent Document 1).
Japanese Patent No. 3912409

The closed cross-section member molded by hydroforming does not have a flange part because it is molded from a pipe material, so it is arranged in a direction intersecting the structural member to be joined as disclosed in Patent Document 1. However, spot welding may be performed with the opening of the closed section member formed by hydroforming open. However, when it is joined to another member so as to close the opening of the closed cross-section member formed by hydroforming, the inside is isolated from the outside, and the undercoat coating liquid is contained inside in the chemical conversion process etc. There is a problem that it is difficult to wrap around.
Therefore, a separate process such as forming a separate air vent hole in the closed cross-section member molded with a small number of processes by hydroforming is required, which may increase the number of manufacturing steps. In addition, there is a case where the rigidity of the vehicle body is deteriorated by forming an air vent hole while the vehicle body rigidity is improved by being constituted by a closed cross-section member.

  Accordingly, the present invention provides a joint structure for a closed cross-section member that does not require a separate air vent hole, with the joint portion between the lower member molded by hydroforming and the upper member serving as an air vent hole. The purpose is to do.

In order to achieve the above object, the invention described in claim 1 is directed to an opening (for example, an embodiment) that opens upward in a lower member (for example, the bulkhead lower frame 4 in the embodiment) molded by hydroforming. In the joint structure of a closed cross-section member that is provided with an upper opening 10), and an upper member (for example, the bulkhead upper frame 3 in the embodiment) is coupled to the opening so as to close the opening. A protruding portion (for example, the protruding portion 26 in the embodiment) larger than the width dimension of the upper member (for example, the width dimension w in the embodiment) is provided in a part of the opening of the member, and the protruding portion The upper member is connected.
By comprising in this way, parts other than a junction part can be effectively utilized as an air vent hole by partially joining between the overhang | projection part of a lower side member, and an upper side member.

According to the second aspect of the present invention, gaps (for example, the first gap CL1 and the second gap CL2 in the embodiment) are provided between the protruding portion of the opening of the lower member and the upper member. It is characterized by that.
By comprising in this way, the clearance gap between the overhang | projection part of the opening part of the said lower side member and the said upper side member can be made into an air vent hole.

According to the first aspect of the invention, by partially joining the protruding portion of the lower member and the upper member, a portion other than the joint portion can be effectively used as an air vent hole. This eliminates the need to provide a separate air vent hole. For example, in the chemical conversion process such as the painting process, it is easy to vent the air inside the lower member, so that the undercoating liquid can be quickly immersed, and the production of coating defects is eliminated. Efficiency can be improved.
According to the invention described in claim 2, since the gap between the protruding portion of the opening of the lower member and the upper member can be an air vent hole, the inner surface of the wall portion of the lower member Is used as a guide for venting air, and the air can be smoothly vented.

Next, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view of a front part of a vehicle body of an automobile, and FIG. 2 is a perspective view of a main part of FIG. 1 and 2, a frame-shaped front bulkhead 2 for protecting a radiator (not shown) is provided at the front portion of the vehicle body 1.
The front bulkhead 2 is composed of an upper member 3 as an upper member that is disposed on the upper side of the bulkhead upper frame, and a bulkhead upper frame 3 that constitutes a lower part and has both ends rising upward. It is composed of a bulkhead lower frame 4 as a lower member located on the lower side.

  The bulkhead upper frame 3 is composed of an upper side portion 5 extending in the vehicle width direction and an oblique side portion 6 in which both ends of the upper side portion 5 extend obliquely outward. The bulkhead lower frame 4 is composed of a horizontal portion 8 and side portions 9 that rise while gently curving from both ends of the horizontal portion 8. As shown in FIGS. 3 and 4, the upper opening 10 of the side portion 9 of the bulkhead lower frame 4 is formed on the lower wall 7 between the upper side portion 5 and the oblique side portion 6 of the bulkhead upper frame 3 from the lower side. Butted and welded.

  Here, both the bulkhead upper frame 3 and the bulkhead lower frame 4 are members formed by hydroforming using a pipe material. The upper side portion 5 and the two oblique side portions 6 of the bulkhead upper frame 3 are integrally formed, and the horizontal portion 8 and the two side portions 9 of the bulkhead lower frame 4 are integrally formed. Therefore, the bulkhead upper frame 3 and the bulkhead lower frame 4 are both light-weight members because the ends are opened straight and no flange portion is provided. Further, since both members are molded using a pipe material, the inner space is basically a closed cross-section member that communicates with the outside only at the opening of the terminal when piercing is not performed.

As shown in FIG. 1, the front end portion of the wheel house upper member portion 12 is joined to the opening portion 11 that opens linearly at both ends of the bulkhead upper frame 3.
The bulkhead lower frame 4 is joined to a front end portion of a front side frame 13 having a closed cross-sectional structure, which is a vehicle body skeleton member. The lower side of the damper housing 14 is joined to the front side frame 13, and the outer edge of the damper housing 14 is joined to a front wheel house (not shown). Reference numeral 16 denotes a dash upper panel.

  As shown in FIGS. 3 to 5, the peripheral edge of the upper opening 10 of the bulkhead lower frame 4 is connected to a front wall 20 and a rear wall 21 facing each other, and has a square front extension piece 22 and a rear extension piece 23. Is formed so as to extend from the upper position as it is. Here, the width dimension W (see FIG. 5) between the inner side surfaces 27 and 28 of the front wall 20 and the rear wall 21 of the bulkhead lower frame 4 is the bulkhead upper to which the bulkhead lower frame 4 is partially welded. The overhang portion 26 is formed so as to be larger than the width w between the outer side surfaces 29 and 30 of the front wall 24 and the rear wall 25 of the oblique side portion 6 of the frame 3, and the oblique side portion of the bulkhead upper frame 3. It is designed to accept 6 with sufficient margin.

Specifically, the inner side surfaces 27 and 28 of the front extension piece 22 and the rear extension piece 23 of the upper opening 10 of the bulkhead lower frame 4, the front wall 24 of the oblique side portion 6 of the bulkhead upper frame 3, A first gap CL <b> 1 is formed between the rear wall 25 and the outer side surfaces 29, 30, and the peripheral edge of the upper opening 10 of the bulkhead lower frame 4 and the lower wall 7 of the oblique side 6 of the bulkhead upper frame 3. A second gap CL2 is also formed between the two. In this state, a part of the end surfaces 32 of the side walls 31 and 31 of the upper opening 10 of the bulkhead lower frame 4 is MIG welded to the lower wall 7 of the hypotenuse 6 of the bulkhead upper frame 3 by the MIG weld M. The front extension piece 22 of the upper opening 10 of the head lower frame 4 and the corner portion 33 of the rear extension piece 23 are respectively connected to the front wall 24 and the rear wall 25 of the oblique side portion 6 of the bulkhead upper frame 3 by the MIG welded portion M. Mig welded.
Accordingly, the first gap CL1 and the second gap CL2 are opened as they are in the portion other than the MIG welded portion M, and this portion becomes the air vent hole H.

  Here, on the upper wall 34 of the bulkhead upper frame 3, as shown in FIG. 2, mounting holes 35, 35... For peripheral parts are formed in a plurality of portions including the upper portion of the mounting portion of the bulkhead lower frame 4. Is formed. The bulkhead lower frame 4 also has mounting holes 38 and 38 formed in a plurality of portions of the upper wall 36 of the horizontal portion 8 and a lower portion of the mounting portion of the bulkhead upper frame 3 and in the inner wall 37 of the side portion 9. ing.

  According to the above embodiment, as shown in FIG. 6, the vehicle body 1 is immersed in the electrodeposition liquid D in the electrodeposition tank in a state where it is suspended by an overhead conveyor (not shown) in the coating undercoating step that is a chemical conversion step. The The vehicle body 1 is placed in a tank at an angle of about 30 to 45 degrees obliquely downward at the rear, submerged in the electrodeposition liquid D, moves in the liquid in a horizontal state, and a closed cross-sectional structure provided in each part of the vehicle body 1 during this time. The electrodeposition liquid D enters the portion, and the electrodeposition liquid D adheres to the inner and outer surfaces of the member by the electrodeposition liquid D and is applied. Thereafter, the tank 1 is taken out at an angle of about 30 to 45 degrees with the rear part of the vehicle body 1 facing obliquely upward, and conveyed to the shower process which is the next process of the painting process.

FIG. 7 shows a state of a joint portion between the bulkhead upper frame 3 and the bulkhead lower frame 4 at the beginning when the vehicle body 1 is immersed in the electrodeposition liquid in FIG.
When the vehicle body 1 is immersed in the electrodeposition liquid, the electrodeposition liquid D enters the inside through the attachment holes 35 of the bulkhead upper frame 3 and the attachment holes 38 of the bulkhead lower frame 4 as shown in FIG. In this case, when the electrodeposition liquid D enters from the attachment hole 38, air also escapes from the attachment hole 38.

  The electrodeposition liquid D that penetrates into the bulkhead lower frame 4 fills the bulkhead lower frame 4 in order from the horizontal portion 8, and the extruded air is directed from the horizontal portion 8 to the side portion 9, 9 is smoothly guided along the inner surfaces 27 and 28 of the front wall 20 and the rear wall 21 and finally reaches the lower wall 7 of the bulkhead upper frame 3 and is formed between the MIG welds M. It escapes from H as a bubble. During this time, the internal air in the bulkhead upper frame 3 escapes from the mounting hole 35 of the upper wall 34 as bubbles to the outside. Thus, at the end of the process, the electrodeposition liquid D is reliably filled in the bulkhead upper frame 3 and the bulkhead lower frame 4 as shown in FIG. Therefore, the interior of the bulkhead upper frame 3 and the bulkhead lower frame 4 is reliably filled with the electrodeposition liquid D, so that the undercoating surface can be reliably formed with the electrodeposition liquid.

In particular, in the bulkhead lower frame 4, the side portion 9 is connected to the front wall 20 and the rear wall 21, and the rectangular front extending piece 22 and the rear extending piece 23 extend upward from the same position. Since it is formed, the rising air is smoothly discharged from the air vent hole H at the highest position other than the MIG-welded corner portion 33 of the front extension piece 22 and the rear extension piece 23, which is advantageous in terms of the point. . In addition, the air vent hole H is not specially provided, but is formed in a portion other than the partially formed MIG welded portion M, so that the number of manufacturing steps is increased as compared with the case where a separate air vent hole is provided. I will not let you.
Further, an air vent hole H ′ having an opening area larger than the air vent hole H is easily formed between the corner portion of the bulkhead upper frame 3 having the rectangular cross section and the corner portion of the bulkhead lower frame 4 having the rectangular cross section. It is possible to increase the air bleeding speed, and it is not necessary to form a separate air bleeding hole, so that the rigidity of the vehicle body can be improved.
In this way, by adopting such a coupling structure, the electrodeposition coating film D is difficult to enter because it is difficult for the electrodeposition liquid D to penetrate inside due to the formation of the pipe material by hydroforming. To improve production efficiency.

  The width dimension W between the inner side surfaces 27 and 28 of the front wall 20 and the rear wall 21 of the bulkhead lower frame 4 is that of the oblique side portion 6 of the bulkhead upper frame 3 to which the bulkhead lower frame 4 is partially welded. It is formed as an overhanging portion 26 so as to be larger than the width dimension w between the outer side surfaces 29, 30 of the front wall 24 and the rear wall 25, and has a margin so as to wrap around the oblique side portion 6 of the bulkhead upper frame 3. Since they are designed to be accepted, the bond strength between the two is higher than when they are simply put together.

  The present invention is not limited to the above embodiment. For example, the lower member is a member formed by hydroforming, and the upper member may not be a member formed by hydroforming, but may be a closed section member. It does not have to be. In addition, although the description has been made taking the attachment site of the bulkhead upper frame 3 and the bulkhead lower frame 4 as an example, the present invention is not limited to this.

It is a perspective view of the vehicle body front part of embodiment of this invention. It is a principal part perspective view of FIG. It is a principal part expansion disassembled perspective view of FIG. It is an expansion perspective view of the junction part of FIG. It is sectional drawing which follows the AA line of FIG. It is explanatory drawing of a painting process. It is sectional drawing which shows a mode that an electrodeposition liquid is filled corresponding to FIG. It is sectional drawing which shows the state with which the electrodeposition liquid was satisfy | filled corresponding to FIG.

Explanation of symbols

3 Bulkhead upper frame (upper member)
4 Bulkhead lower frame (lower member, closed section member)
10 Upper opening (opening)
26 Overhang portion CL1 First gap CL2 Second gap

Claims (2)

  In the joint structure of the closed cross-section member in which the lower member formed by hydroforming is provided with an opening that opens upward, and the upper member is coupled to the opening so as to close the opening. A joint structure for a closed cross-section member, wherein a protruding portion larger than the width of the upper member is provided in a part of the opening, and the upper member is coupled to the protruding portion.   The joint structure for a closed cross-section member according to claim 1, wherein a gap is provided between the protruding portion of the opening of the lower member and the upper member.

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