JP3656687B2 - Resistance welding method for hollow frame - Google Patents

Description

【００２６】
中間フレームはＡ６０６３−Ｔ５アルミニウム合金の押出材であり、板材はＡ５１８０−Ｏ材である。中間フレームの厚さは３ｍｍであり、その横断面は１辺長が６０ｍｍの正方角筒である。電極はクロム銅製であり、直径が１６ｍｍであり、先端部の曲率半径は８０ｍｍである。
【００２７】
実施例１は、図４に示すように、中間フレーム２１に１枚の板材２２を抵抗スポット溶接したものである。実施例２は、図５に示すように、実施例１と加圧力及び溶接電流が異なる。実施例３は、図６に示すように、板材２２の外側にダミー部材を模して別の板材２３を配置し、３層重ねで抵抗スポット溶接したものである。実施例４は、図７に示すように、この３層重ねの抵抗スポット溶接を、中空フレームの上面及び下面の２面で同時に行った場合のものである。
【００２８】
これに対し、比較例１は、中間壁を有しない点を除いて図５と同じ条件で抵抗スポット溶接した場合のものである。また、比較例２は、インサート材を使用したこと以外は、比較例１と同一の条件で抵抗スポット溶接した場合のものである。
【００２９】
その結果、表１に示すように、破断試験において、実施例１乃至４及び比較例２はいずれも母材で破断し、溶接部では破断しなかった。従って、溶接強度はいずれも優れたものであった。しかし、実施例１乃至４はインサート材を使用しなかったが、比較例２はインサート材を使用したものであり、前述の如く、インサート材を使用する場合の欠点を有するものである。そして、インサート材を使用しないがその他の条件は比較例２と同様である比較例１は、溶接部の強度が低く、破断試験において溶接部で破断した。このため、実施例１乃至４の評価は○となっているのに対し、比較例１，２の評価は×となっている。
【００３０】
また、実施例１，２は溶接電流が高いのに対し、実施例３，４は３層重ねで抵抗スポット溶接しているので、実施例１，２に比して溶接電流を低減することができた。
【００３１】
以上のように、本発明の実施例１乃至４の場合は、いずれも良好な作業性で良好な溶接品質の溶接部を得ることができた。これに対し、比較例１，２の場合は、溶接品質が低いか、又は溶接作業性が悪いものであった。
【００３２】
【発明の効果】
以上説明したように、本発明によれば、中空フレームの内部に中間壁を設けたので、中空フレームに板材を抵抗溶接する場合に、加圧力を十分高いものとしても、中空フレームに変形が生じることがなく、接合強度が高い溶接部を得ることができる。しかも、本発明によれば、インサート材を使用する必要がないので、その溶接作業性も優れたものである。
【図面の簡単な説明】
【図１】本発明の実施例を示す斜視図である。
【図２】同じくその中間壁の厚さを説明する図である。
【図３】同じくその隅部の丸みがない場合の不都合を説明する図である。
【図４】本発明の実施例１の溶接方法を説明する図である。
【図５】本発明の実施例２の溶接方法を説明する図である。
【図６】本発明の実施例３の溶接方法を説明する図である。
【図７】本発明の実施例４の溶接方法を説明する図である。
【符号の説明】
１：中空フレーム
２：中間壁
３：隅部
４：板材
５，７：ダミー部材
６，８：先端部
９，１０：凹部
１１，１２：電極
１３：電極先端部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resistance welding method for a hollow frame in which a hollow frame made of aluminum or an aluminum alloy and a plate material are welded by resistance welding such as resistance spot welding, and more particularly to a resistance welding method for a hollow frame capable of increasing the applied pressure.
[0002]
[Prior art]
The aluminum or aluminum alloy hollow frame used as the structural material and the plate material are welded by resistance spot welding. When the hollow frame and the plate material are joined by resistance spot welding, it is necessary to weld with a high pressure to increase the joining strength. However, in this resistance spot welding, it is necessary to apply a plate material to the surface to be welded of the hollow frame and press the plate material against the surface of the hollow frame with a pair of electrodes from the outside. The surface of the hollow frame is bent by the applied pressure, and the hollow frame is deformed into a drum shape. For this reason, the pressurizing force could not be increased when resistance spot welding the hollow frame.
[0003]
Therefore, conventionally, in order to weld the hollow frame under a low pressure, there is a technique of resistance welding by interposing an insert material having a composition adjusted so that a thermite reaction occurs between the hollow frame and the plate material. It has been proposed (JP-A-8-132252).
[0004]
[Problems to be solved by the invention]
However, in the said prior art, the operation | work which apply | coats insert material to the surface of a hollow frame, the installation for hardening the applied insert material with heat, and its management are required. For this reason, the conventional resistance welding method using this insert material has the fault that processing cost is high.
[0005]
The present invention has been made in view of such problems, and provides a resistance welding method for a hollow frame that can apply a high pressure and can increase the joining strength without using an insert material. For the purpose.
[0006]
[Means for Solving the Problems]
In the resistance welding method for a hollow frame according to the present invention, an aluminum or aluminum alloy plate is applied to the outer surface of an aluminum or aluminum alloy hollow frame, and the plate is pressed against the hollow frame by a pair of electrodes and energized. In the resistance welding method of a hollow frame in which both are resistance welded, an intermediate wall is formed inside the hollow frame, the thickness of which is substantially the same as the melt diameter by resistance welding and connecting between the parts pressed by the electrodes. A pair of dummy members having an L-shaped cross section covering a surface pressed by the electrode and a surface orthogonal thereto on the outer side of the plate material and having portions overlapping each other at the end portions And the pair of dummy members are welded together with the plate member and the hollow frame .
[0008]
The dummy member may have a recess formed in advance on the outer surface of the portion to be welded by the electrode, and the dummy member may be positioned with respect to the hollow frame so that the recess aligns with the intermediate wall. Moreover, it is preferable that the surface of the intermediate wall and the inner surface of the hollow frame intersect each other with a radius of curvature of 1 mm or more.
[0011]
In the present invention, an intermediate wall whose thickness is substantially the same as the melt diameter by resistance welding is provided inside the hollow frame so as to communicate between the parts pressed by the electrodes. Thus, even by pressing the plate material in the hollow frame through the electrodes, since there is no the hollow frame is deformed, it can be resistance spot welding by applying the bonding strength on the optimum pressing force. Therefore, no insert material is required in the present invention.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. The hollow frame 1 has a rectangular cross section, and an intermediate wall 2 that connects the center of the upper wall and the center of the lower wall of the frame is formed inside the hollow. The thickness of the intermediate wall 2 is substantially equal to the melt nugget diameter at the time of welding. The corner 3 between the upper and lower walls of the frame and the intermediate wall 2 is rounded with a curvature radius of 1 mm or more. The hollow frame 1 having such a shape is formed by extrusion molding of aluminum or an aluminum alloy. The thickness of the intermediate wall 2 has substantially the same size as the size of the molten nugget at the time of welding.
[0013]
On the outer surface of the upper wall and the lower wall of the hollow frame 1, an aluminum or aluminum alloy plate 4 is overlaid so that the end portions thereof do not protrude from the upper wall and the lower wall of the hollow frame 1.
[0014]
Then, dummy members 5 and 7 having an L-shaped cross section are disposed outside the plate member 4 so as to sandwich these plate members 4 between the hollow frame 1. The dummy members 5 and 7 are aluminum or aluminum alloy press material, rolled material, extruded material, or the like. The dummy members 5 and 7 are bent 90 ° from the upper surface and the lower surface of the hollow frame 1 to cover the side surfaces. In particular, the front end portion 6 of the side surface extension portion of the dummy member 5 disposed above is further bent. The dummy member 7 is adapted to be superposed on the tip 8 of the side surface extension. The upper and lower surfaces (ie, outer surfaces) of the dummy members 5 and 7 are aligned with the intermediate wall 2 when they are placed on the upper wall, the lower wall, and the side wall of the hollow frame 1. In the position, recesses 9 and 10 extending linearly along the intermediate wall 2 are formed.
[0015]
Next, a description will be given of a method of the present embodiment in which the intermediate frame 1 having such a shape and the plate members 4 and 5 are resistance spot welded using the dummy members 5 and 7. First, the plate material 4 is stacked on both the upper and lower surfaces of the hollow frame 1, and the dummy members 5 and 7 are further stacked on the plate material 4 so that the front end portion 6 of the dummy members 5 and 7 are fitted.
[0016]
Next, the upper electrode 11 and the lower electrode 12 are pressed against predetermined welding locations in the concave portions 9 and 10 of the dummy members 5 and 7, and the electrodes 11 and 12 are pressed against the dummy members 5 and 7, the plate material 4 and the hollow frame 1 with predetermined pressure. Press. In this pressurized state, a predetermined pulse current is applied between the electrodes 11 and 12 in a predetermined cycle, and the plate member 4 and the hollow frame 1 including the dummy members 5 and 7 are resistance spot welded. In this case, in this embodiment, since the intermediate wall 2 is provided in the portion of the hollow frame 1 to which the electrodes 11 and 12 are pressurized, the electrodes 11 and 12 can provide a high applied pressure that is optimal in terms of bonding strength. Even if it is applied to the frame 1, there is no possibility that the upper wall and the lower wall of the hollow frame 1 bend and deform. Thus, since resistance spot welding is performed in a state where a sufficiently high pressure is applied, extremely high joint strength can be obtained.
[0017]
Moreover, since the thickness of the intermediate wall 2 is substantially the same as the nugget diameter of resistance spot welding, desired joining quality can be easily obtained. The structural design of spot welding is carried out according to the nugget diameter and the number of welding points. For this reason, if the nugget diameter is limited by the size of the intermediate wall 2 as in this embodiment, only the number of welding points may be determined according to the desired strength. Therefore, it is possible to easily carry out the welding design according to the desired joint strength. That is, FIG. 2 is a schematic diagram showing the relationship between the melt nugget diameter and the thickness of the intermediate wall. However, for simplicity of explanation, the dummy members 5 and 7 are not shown. The tip portion 13 of the electrode 11 presses the plate member 4 against the upper wall of the hollow frame 1 and energizes between the electrodes, whereby the contact portion between the plate member 4 and the intermediate frame 1 is heated by resistance and melted, and the molten nugget 14 is It is formed. In this case, a current path is determined by the diameter d ₁ of the contact region between the electrode tip 13 and the plate member 4 and the thickness d ₃ of the intermediate wall 2, and the plate member 4 and the intermediate frame 1 are separated in the current passage. The close contact part generates heat and melts. Therefore, when the electrode 11 having a curvature or contact plane such that the electrode tip portion 13 satisfies d ₁ ≧ d ₃ is used, the nugget diameter d ₂ becomes d ₂ = d ₃ , and the nugget diameter is equal to the thickness of the intermediate wall 2. Become. Therefore, if the curvature of the electrode tip or the contact plane is in the condition of d ₁ ≧ d ₃ as described above, the welding current can be reduced by selecting a slightly overcurrent condition as the welding condition. There is no need to control the size of the nugget diameter for each welding by strictly adjusting the size and the like, and the desired welding quality can be easily ensured.
[0018]
In this embodiment, the radius of curvature of the corner 3 is 1 mm or more. Thus, by providing roundness at the corner 3 and setting the radius of curvature to 1 mm or more, it is possible to avoid inconvenience when the positions of the electrodes 11 and 12 are shifted with respect to the intermediate wall 2. That is, as shown in FIG. 3, when the corner formed by the inner surface of the intermediate frame 1 and the intermediate wall 2 is not rounded, when the center of the electrode tip 13 is slightly shifted from the center position of the intermediate wall 2, The passage is also deviated from the center position of the intermediate wall 2 and is inclined with respect to the center direction of the intermediate wall 2. For this reason, the heat generating part is also deviated from the central direction of the intermediate wall 2. On the other hand, the close contact portion between the plate member 4 and the hollow frame 1 generated by the pressing of the electrode 11 is close to the position on the center line of the intermediate wall 2. A large amount of heat is generated at a low-temperature site. If it does so, explosion may occur and a hole may open in a member. However, as in this embodiment, if the inner surface of the intermediate frame and the surface of the intermediate wall 2 intersect with each other with a predetermined radius of curvature, even if the electrode position slightly deviates, A shift between the heat generating portion and the close contact portion is prevented, and the risk of explosion is also eliminated.
[0019]
Further, in this embodiment, when the dummy members 5 and 7 are positioned and arranged with respect to the hollow frame 1, the concave portions 9 and 10 formed on the outer surface thereof are positioned at positions where they are aligned with the intermediate wall 2. For this reason, by determining the pressing positions of the electrodes 11 and 12 using the recesses 9 and 10 as a guide, the electrodes 11 and 12 can be positioned so as to be aligned with the intermediate wall 2 very easily and with high accuracy. In particular, when the dummy members 5 and 7 are arranged outside the plate member 4 as in the present embodiment, it is difficult to recognize the position of the intermediate wall 2. For this reason, it is extremely effective to form the concave portions 9 and 10 for marks on the outer surfaces of the dummy members 5 and 7.
[0020]
In this embodiment, in addition to the hollow frame 1 and the plate material 4 that should be originally welded, the dummy members 5 and 7 are also welded together. For this reason, compared with the case where there is no dummy member 4, the electric current which should be given to a welding part from the electrodes 11 and 12 can be reduced. The hollow frame 1 and the plate material 4 are made of aluminum or an aluminum alloy. However, since this aluminum or aluminum alloy has high thermal conductivity and heat is easily dispersed, a required amount of heat generated between the hollow frame 1 and the plate material 4 can be obtained. In order to obtain it, a current value about three times that of resistance spot welding of a steel material is required. However, in the case of the present embodiment, since the plate material 4 has a three-layer structure sandwiching the dummy members 5 and 7 and the hollow frame 1, the plate material 4 is connected to both the dummy members 5 and 7 and the hollow frame 1. It has a contact surface and has a contact area twice that of the case where the dummy members 5 and 7 are not provided. For this reason, about each board | plate material 4, since heat_generation | fever arises in the front and back both surfaces, the board | plate material 4 can be heated and fuse | melted with high efficiency. Therefore, the current to be input can be reduced.
[0021]
Further, since the dummy members 5 and 7 have a shape in which the tip portions 6 and 8 are overlapped with each other, water or the like is prevented from entering through the gap between the dummy member 5 and the dummy member 7. can do. A slight gap 15 is provided between the tip of the lower dummy member 7 and the upper dummy member 5. For this reason, when the dummy members 5 and 7 are pressed by the electrodes 11 and 12, even if the hollow frame 1 is slightly bent, the deformation can be absorbed by the gap 15. Thus, by making the dummy members 5 and 7 not the U-shaped integral but the L-shaped divided shape, the dummy member 5.7 can maintain the welded portion in a parallel state even when the electrode is pressed. It is possible to prevent deterioration of welding workability.
[0022]
Thus, according to the present embodiment, the hollow frame made of aluminum or aluminum alloy and the plate material can be resistance-welded with high efficiency without deforming the hollow frame and without using the insert material. it can.
[0023]
Needless to say, the present invention is not limited to the above embodiments. For example, the intermediate wall may be provided so as to communicate at least the welded portion and the opposing portion, and another intermediate wall may be provided in addition to the welded portion. For example, the hollow frame can have various cross-sectional shapes such as a rice field, as well as a daily cross-sectional shape as in the above embodiment. Moreover, it is good also as welding a board | plate material only to one surface of a hollow frame, without welding a board | plate material to two surfaces of a hollow frame like the said Example.
[0024]
【Example】
Hereinafter, the results of an actual resistance spot welding test by the method of the present invention will be described by comparing an example that falls within the scope of the present invention and a comparative example that falls outside the scope of the present invention. Table 1 below shows the welding conditions, fracture modes, and evaluation results of the examples and comparative examples.
[0025]
[Table 1]

[0026]
The intermediate frame is an extruded material of A6063-T5 aluminum alloy, and the plate material is an A5180-O material. The thickness of the intermediate frame is 3 mm, and the cross section thereof is a square cylinder having a side length of 60 mm. The electrode is made of chrome copper, has a diameter of 16 mm, and has a radius of curvature at the tip of 80 mm.
[0027]
In the first embodiment, as shown in FIG. 4, one plate material 22 is resistance spot welded to the intermediate frame 21. As shown in FIG. 5, Example 2 differs from Example 1 in the applied pressure and welding current. In Example 3, as shown in FIG. 6, another plate member 23 is arranged on the outside of the plate member 22 in the form of a dummy member, and resistance spot welding is performed in three layers. In Example 4, as shown in FIG. 7, this three-layer resistance spot welding is performed simultaneously on the two surfaces of the upper surface and the lower surface of the hollow frame.
[0028]
On the other hand, Comparative Example 1 is a case where resistance spot welding is performed under the same conditions as in FIG. 5 except that the intermediate wall is not provided. Moreover, the comparative example 2 is a thing at the time of carrying out resistance spot welding on the same conditions as the comparative example 1 except having used insert material.
[0029]
As a result, as shown in Table 1, in the break test, Examples 1 to 4 and Comparative Example 2 all broke at the base material and did not break at the weld. Accordingly, the welding strength was excellent. However, although Examples 1 to 4 did not use an insert material, Comparative Example 2 uses an insert material, and has the disadvantages of using an insert material as described above. And although the insert material is not used, Comparative Example 1 in which other conditions are the same as those of Comparative Example 2 has a low strength of the welded portion, and fractured at the welded portion in the fracture test. For this reason, the evaluation of Examples 1 to 4 is ◯, whereas the evaluation of Comparative Examples 1 and 2 is ×.
[0030]
Moreover, since Examples 1 and 2 have a high welding current, Examples 3 and 4 are resistance spot welded in three layers, so that the welding current can be reduced compared to Examples 1 and 2. did it.
[0031]
As described above, in each of Examples 1 to 4 of the present invention, it was possible to obtain a weld portion having good workability and good weld quality. On the other hand, in Comparative Examples 1 and 2, the welding quality was low or the welding workability was poor.
[0032]
【The invention's effect】
As described above, according to the present invention, since the intermediate wall is provided inside the hollow frame, when the plate material is resistance-welded to the hollow frame, the hollow frame is deformed even if the applied pressure is sufficiently high. And a weld with high joint strength can be obtained. And according to this invention, since it is not necessary to use an insert material, the welding workability | operativity is also excellent.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of the present invention.
FIG. 2 is a view for explaining the thickness of the intermediate wall.
FIG. 3 is a diagram for explaining inconvenience when the corner is not rounded.
FIG. 4 is a diagram illustrating a welding method according to Example 1 of the present invention.
FIG. 5 is a diagram illustrating a welding method according to a second embodiment of the present invention.
FIG. 6 is a diagram illustrating a welding method according to a third embodiment of the present invention.
FIG. 7 is a diagram illustrating a welding method according to Example 4 of the present invention.
[Explanation of symbols]
1: hollow frame 2: intermediate wall 3: corner 4: plate material 5, 7: dummy member 6, 8: tip 9, 10: recess 11, 12: electrode 13: electrode tip

Claims (3)

In a resistance welding method for a hollow frame in which an aluminum or aluminum alloy plate is applied to the outer surface of an aluminum or aluminum alloy hollow frame, and the plate is pressed against the hollow frame by a pair of electrodes, and both are resistance-welded. In the hollow frame, an intermediate wall having a thickness substantially the same as a melt diameter obtained by resistance welding and communicating between the parts pressed by the electrodes is formed , and the outer side of the plate member is interposed therebetween. A pair of dummy members having an L-shaped cross section covering a surface pressed by the electrode and a surface orthogonal to the surface and having portions overlapping each other are disposed on the end portions, and the pair of dummy members is A resistance welding method for a hollow frame, comprising welding together with a plate material and the hollow frame . The dummy member has a concave portion formed in advance on an outer surface of a portion to be welded by the electrode, and the dummy member is positioned with respect to the hollow frame so that the concave portion is aligned with the intermediate wall. The resistance welding method of the hollow frame of Claim 1 . The resistance welding method for a hollow frame according to claim 1 or 2 , wherein the surface of the intermediate wall and the inner surface of the hollow frame intersect with each other with a radius of curvature of 1 mm or more.

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