JP2004344942A - Method for welding and assembling frame structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which other parts are not required and deformation with welding is surely prevented on the assumption that frame elements are tacked before both are welded to each other. <P>SOLUTION: Before welding a side sill 2 consisting of an aluminum base extruded material and a cross-member 3 in the form of a T-joint, both are tacked. In the tacking, a plurality of projection parts 6 for joining are preliminarily formed on the end face of the opening of the cross-member 3 and projection welding is performed with these projection parts 6 for joining. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for welding and assembling a frame structure, for example, to a method for welding and assembling a frame structure in which a vehicle body frame is assembled by welding and joining frame elements made of extruded aluminum.
[0002]
[Prior art]
As a method of assembling a frame structure using an aluminum-based extruded material having a closed cross-section structure as a frame element, for example, those described in Patent Documents 1 and 2 are known.
[0003]
In other words, considering that aluminum-based extruded materials as frame elements are butted together, and the entire periphery of the butted parts are suddenly welded by MIG welding or the like, the dimensional accuracy of the frame structure must be reduced due to thermal deformation. According to the technology described in Patent Document 1, for example, when welding aluminum-based extruded materials having a rectangular cross section, deformation is suppressed by optimizing the direction and order of welding, and the technology described in Patent Document 2 is also disclosed. In this method, when the aluminum-based extruded materials are butted together, a reinforcing material that straddles both is temporarily attached in advance by spot welding, and thereafter, main welding such as arc welding is performed to suppress deformation.
[0004]
[Patent Document 1]
JP-A-10-324265 (FIG. 1)
[0005]
[Patent Document 2]
JP-A-2002-356177 (FIG. 1)
[0006]
[Problems to be solved by the invention]
In the technology described in Patent Document 1, it is necessary to reconsider the direction and order of welding each time according to the cross-sectional shape and plate thickness of the aluminum-based extruded material to be used, and also the welding conditions. There is a limit on the above.
[0007]
Further, in the technique described in Patent Literature 2, melting and solidification are performed each time a temporary attachment portion is formed by spot welding, so that it is difficult to avoid deformation due to the temporary attachment, and the dimensional accuracy of the frame structure is improved. Has limitations. In addition, a reinforcing material is required as a separate component, and the reinforcing material requires bending or the like, which undesirably increases costs due to an increase in the number of parts and processing steps.
[0008]
The present invention has been made in view of such a problem, and presupposes that the frame elements are temporarily attached to each other prior to welding the frame elements, but without requiring a separate part and An object of the present invention is to provide a method capable of preventing deformation accompanying welding.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 is a method for forming a frame structure by welding a plurality of bar-shaped frame elements made of an aluminum-based material to each other in the form of a T-joint, and then performing welding. By forming a very small joining projection in advance so that it is evenly arranged on the end face of the specific frame element to be abutted against the frame element, and performing projection welding with this joining projection The present invention is characterized in that the frame elements are temporarily attached to each other, and thereafter, the butted portions of the frame elements are subjected to main welding.
[0010]
In this case, projection welding as temporary attachment is performed while applying pressure to both frame elements while energizing both frame elements, as is well known, while main welding is, for example, MIG (MIG) welding. Further, the frame element is an extruded material having a closed cross-sectional shape as described in claim 2, and a plurality of frame elements are arranged so as to be evenly arranged on the end face of a specific frame element as described in claim 3. It is desirable to form a joining projection having an extremely small area in order to reliably prevent deformation.
[0011]
Therefore, according to the first aspect of the present invention, prior to the main welding, the temporary attachment by the projection welding is performed with the joining projections evenly arranged on the abutting surfaces of the frame elements. In this case, since the joining protrusions are evenly arranged on the abutting surface, heat conduction near the abutting surface becomes uniform, so that it is possible to temporarily attach without thermal deformation. It becomes.
[0012]
【The invention's effect】
According to the first aspect of the present invention, the thermal deformation at the time of tacking can be prevented beforehand, so that the dimensional accuracy of the frame structure is improved, and the welded joint structure is not required because a separate part is not required unlike the conventional case. Simplification and cost reduction.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and the following drawings are views showing a preferred embodiment of the present invention, and show an example in which an automobile body frame 1 is assembled as a frame structure as shown in FIG.
[0014]
The body frame 1 shown in FIG. 5, which is a frame structure, has a closed cross-sectional structure between the side sills 2 and 2 having a substantially parallel closed cross-sectional structure which will function as frame elements. By arranging a pair of front and rear cross members 3 and 3 in a bridging manner, abutting the side sills 2 and 2 with the cross members 3 and 3 and welding them together in the form of a T joint, for example, by MIG welding. Assembled. Further, a triangular member support 4 is arranged from the inside at the corner formed by each side sill 2, 2 and one cross member 3, and two sides of the member support 4 are welded to the side sill 2 and the cross member 3, respectively. Has been reinforced. Reference numeral 5 indicates a weld bead formed by fillet welding of MIG welding. Each of the side sill 2, the cross member 3 and the member support 4 is made of aluminum or an aluminum alloy. In particular, the side sill 2 and the cross member 3 are made of a rectangular bar-shaped extruded material having a uniform cross section.
[0015]
FIG. 1 shows the details of the butted portion of the side sill 2 and the cross member 3. At the open end face of the cross member 3 to be abutted against the side surface of the side sill 2, small cylindrical joining protrusions are provided at the four corners. 6 are formed in advance. Since the plurality of joining projections 6 play an important function in projection welding for temporarily fixing the side sill 2 and the cross member 3 as described later, they are equal or symmetrical in the vertical and horizontal directions. Arrangement.
[0016]
FIG. 2 shows a schematic structure of a welding facility for temporarily attaching the side sill 2 and the cross member 3 to each other. As shown in FIG. 2, a fixed-side electrode 8 is mounted on the support frame 7, and a movable-side electrode 9 facing the fixed-side electrode 8 is slidably mounted via a linear guide 10. The movable-side electrode 9 also serves as a gripper for holding the cross member 3 as described later, and the movable-side electrode 9 can move forward and backward with respect to the fixed-side electrode 8 in accordance with the expansion and contraction operation of the pressing cylinder 11. I have. The two electrodes 8 and 9 are connected to a control panel 13 of the welding machine main body via a power supply cable 12.
[0017]
As is clear from FIG. 2, the side sill 2 is positioned and held so as to come into surface contact with the fixed-side electrode 8, while the cross member 3 is positioned and held on the movable-side electrode 9 also serving as a gripper. Cross member 3 is at right angles.
[0018]
When the pressurizing cylinder 11 is extended at the same time when the welding current is applied to both the electrodes 8 and 9, the cross member 3 supported by the movable electrode 9 moves toward the side sill 8 together with the movable electrode 9. Eventually, each joining protrusion 6 on the end surface of the cross member 3 comes into pressure contact with the side surface of the side sill 2.
[0019]
When each of the joining protrusions 6 is pressed against the side sill 2, a welding current flows intensively on the minute joining protrusions 6, so that the respective joining protrusions 6 are melted by resistance heat at that time, and the pressure is applied. It is gradually crushed by the pressure of the cylinder 11. With the crushing deformation of the joining projection 6, the entire opening end surface of the cross member 3 comes into close contact with the side surface of the side sill 2. , The side sill 2 and the cross member 3 are temporarily attached by solidification of the joining projection 6, that is, by projection welding.
[0020]
In this case, although a part of the side sill 2 and the cross member 3 corresponding to each of the joining projections 6 as a temporary attachment portion is likely to undergo some thermal deformation as the individual joining projections 6 are melted and solidified, Since the four joining projections 6 arranged uniformly or symmetrically in the vertical and horizontal directions are simultaneously melted and solidified, the heat conduction on the side sill 2 and the cross member 3 side is uniform, and uniform without thermal deformation due to welding. At the same time, temporary attachment can be performed.
[0021]
In addition, since only the joining protrusion 6 is melted, the cross member 3 is pushed in until it abuts the side sill 2, so that the cross member 3 does not shrink in the longitudinal direction, and this also provides high precision. The vehicle frame 1 can be assembled.
[0022]
In this way, when the side sill 2 and the cross member 3 are temporarily attached by projection welding and the vehicle body frame 1 in the form of FIG. 5 is temporarily assembled, the entire periphery of the butted portion of the side sill 2 and the cross member 3 which are the temporarily attached portions. The main welding is performed by, for example, fillet welding by MIG welding.
[0023]
FIG. 3 shows a second embodiment of the present invention. In this embodiment, instead of the plurality of joining projections 6 having the independent projection shape, the opening end surface of the cross member 3 is arranged from the back side. An annular tapered wall 16 having a substantially wedge-shaped cross section and having a gradually decreasing thickness toward the opening end face is formed as a joining projection having a small area. Since the tapered wall portion 16 functions as a joining protrusion, a part of the cross member 3 is melted by projection welding, so that the total length of the cross member 3 is set in consideration of the melting margin.
[0024]
FIG. 4 shows a third embodiment of the present invention. In this embodiment, the cross-member 3 has a thicker opening end face instead of the independent projection-like plurality of joining projections 6. A uniform and thin annular joining projection 26 is formed.
[0025]
In the second and third embodiments, the contact area of the tapered wall portion 16 or the joining projection 26 with the side sill 2 is substantially equal to that of the independent projection-shaped joining projection 6 of the first embodiment. In spite of the presence, the tapered wall portion 16 or the joining projection 26 comes into uniform contact over the entire circumference of the opening end face of the cross member 3, so that the entirety of the opening end face can be temporarily attached. The attachment strength is improved, and thermal deformation can be further suppressed.
[0026]
In particular, in the second embodiment, since the melting allowance (melting area) of the tapered wall portion 16 gradually increases during projection welding (temporary attachment), it occurs when the opposite side of the cross member 3 is welded. There is an advantage that length errors due to contraction in the longitudinal direction can be absorbed.
[Brief description of the drawings]
FIG. 1 is a view showing a preferred first embodiment of the present invention, in which (A) is an exploded perspective view of a butted portion of a side sill and a cross member, and (B) is a line a-a in FIG. Sectional view along.
FIG. 2 is a schematic explanatory view of welding equipment for performing temporary attachment (projection welding) of the side sill and the cross member shown in FIG.
3A and 3B are diagrams showing a second preferred embodiment of the present invention, wherein FIG. 3A is a perspective view of a main part of a cross member, and FIG. 3B is a cross-sectional view taken along line bb of FIG.
FIGS. 4A and 4B are diagrams showing a third preferred embodiment of the present invention, wherein FIG. 4A is a perspective view of a main part of a cross member, and FIG. 4B is a cross-sectional view taken along line cc of FIG.
FIG. 5 is a perspective view showing a schematic structure of a vehicle body frame as an example of a frame structure.
[Explanation of symbols]
1. Body frame (frame structure)
2. Side sill (frame element)
3: Cross member (frame element)
4 Member support 6 Joining protrusion 8 Fixed electrode 9 Movable electrode 11 Pressurizing cylinder 16 Tapered wall (joint protrusion)
26 ... joining projection

Claims (5)

A method of forming a frame structure by welding a plurality of bar-shaped frame elements made of an aluminum-based material to each other in a form of a T-joint, and then performing welding.
Forming a very small joining protrusion in advance so as to be evenly arranged on the end surface of the specific frame element to be abutted against the counterpart frame element,
By applying projection welding with this joining projection, frame elements are temporarily attached to each other,
Thereafter, a main assembly is welded to a butt portion between the frame elements, and a welding and assembling method for the frame structure is provided. The method according to claim 1, wherein the frame element is an extruded member having a closed cross-sectional shape. The method for welding and assembling a frame structure according to claim 1 or 2, wherein a plurality of joining projections having a very small area are formed so as to be evenly arranged on an end face of a specific frame element. The joining projection part is formed as an annular and substantially wedge-shaped cross-section in which the thickness gradually decreases from the inner side of the end face of the specific frame element toward the end face. 3. The method for welding and assembling a frame structure according to 1 or 2. The frame according to claim 1, wherein the joining protrusion is formed as an annular member having a constant thickness from an inner side of an end surface of a specific frame element toward the end surface. A method for welding and assembling structures.

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