JPH0356830B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention connects a shaft body such as a pin or bolt with a head integrally formed on the upper part by projection welding in a fitted state to a joining base material. This invention relates to welding and joining of pins and the like.

(Prior art) As a structure in which the head of a shaft body such as a pin or bolt is joined to a joining base material by projection welding, Japanese Utility Model Application No. 54-88024 discloses an annular projection on the seat surface of the bolt head. Articles with provisions are listed. However, with such a structure, it is difficult to uniformly melt the annular protrusion over the entire circumference, and a large-capacity projection welding machine is required, so it is not actually widely used.

By the way, as shown in FIG. 1, a bracket 3 provided at the lower side of the seat back 2 of the automobile seat 1 and a support bracket 5 fixed to the vehicle body floor 4 are connected by a double hinge via an intermediate connecting bracket 6. In the case where they are connected, the pin 7 that connects the seat side bracket 3 and the intermediate connection bracket 6 is joined by the projection welding described above.

Conventionally, the above-mentioned pin 7 has been used in which the seat 9 of the head 8 of the pin 7 is tapered, as shown in FIG. However, although this type of pin 7 requires less welding current than the one in the above publication, it still requires a large-capacity projection welder, and if the capacity is insufficient, it can simply be Simply joining by projection welding does not provide the necessary and sufficient joint strength; therefore, after projection welding, auxiliary welding such as arc welding is performed to ensure the necessary joint strength. It was the current situation.

Further, in the pin 7 described above, since the tapered portion 9 comes into contact with the joining base material, it is difficult to ensure the straightness of the pin 7, and there is also a problem that welding defects occur in this aspect as well.

(Objective of the Invention) An object of the present invention is to provide a welded joint structure such as a pin, which has a simple structure but can obtain extremely good joint strength.

(Structure of the Invention) Therefore, in the present invention, the circumference of the seat surface of the pin or the hole in the joining base material has a circumscribed circle that is slightly larger than the outer circumferential surface of the head of the pin, etc., and the axis of the pin etc. A stepped portion having an axially orthogonal cross section in the shape of a triangle with the center of gravity cut out by the outer circumferential circle of the head of the pin, etc. is formed, and the head of the pin, etc. and the bonding base material are connected through the stepped portion. The structure is such that they are joined by projection welding.

That is, the above-mentioned step becomes a medium to form an initial molten pool, which is pushed out from the step to the part without step by the pressure applied to the head of the pin, etc. It is possible to weld and join the head and the joining base material while filling the gap between them.

(Effects of the Invention) According to the present invention, the joint strength of pins and other base materials is greatly improved by projection welding, and even when high joint strength is required, there is no need for auxiliary welding. Work can be done easily and in a short time, and work efficiency is significantly improved. Furthermore, since weldability is improved, the capacity of the projection welding machine can be reduced accordingly.

Further, according to the present invention, since the two contact each other via the stepped portion, straightness can be easily ensured.

(Example) Examples of the present invention will be specifically described below.

As shown in FIGS. 3 and 4, the bearing surface side of the head 11 of the pin 10, that is, the lower surface side that is pressed against the joining base material 12, has a constant thickness of chords A, B, and C of equal length. is removed to form a step portion 13 having a substantially regular triangular shape. The planar shape of the stepped portion 13 is similar to that of the pin head 1.
It has a circumscribed circle E that is appropriately larger than the outer circumferential circle D of 1,
The inscribed circle is slightly larger than the outer circumferential circle F of the shaft portion 10a of the pin 10, and each top of the regular triangle whose center of gravity G coincides with the axis O of the pin 10 is determined by the outer circumferential circle of the pin head 11. It has the basic shape taken.

By forming the triangular step portion 13 in this manner, a total of three arch-shaped gaps 14 are formed between the pin head 11 and the joining base material 12.

Now, when the pin head 11 is pressurized from above with a pressure P and a strong current is passed in pulses from the pin head 11 to the base metal 12 to be welded, so-called projection welding is performed. , the current flows through the step 13, a molten pool is formed in the step 13, this molten pool is gradually pushed out into the surrounding gap 14 by the pressurizing force P, and the pin head 11 is inserted into the step 1.
It sinks slightly in response to the melting of 3. In this way, the void 14 is filled with molten metal, and the pin head 11 is satisfactorily joined onto the joining base material 12 without any gaps, thereby greatly improving the joining strength.

In addition, since the pin head 11 and the bonding base material 12 abut through the flat stepped portion 13, the pin 10
The straightness can be made extremely good.

In the above embodiment, the stepped portion 13 was provided on the side of the pin head 11, but the lower surface of the pin head 11 was made flat,
The stepped portion may be formed around the pin hole 12a of the bonding base material 12.

Further, it goes without saying that the welded joint structure of pins and the like according to the present invention is not limited to use in the hinge bracket of an automobile seat as shown in FIG.

[Brief explanation of drawings]

Fig. 1 is a side view of an automobile seat showing an example of a welded joint structure using pins, etc. Fig. 2 is a side view of a conventionally used joining pin, and Fig. 3 is a side view of an example of a welded joint structure of the present invention. The side view of the joining pin shown in FIG. 4 is also a plan view. 10...Pin, 11...Head, 12...Joining base material, 13...Step, 14...Gap.

Claims (1)

[Claims] 1 In a welded joint structure for pins, etc., in which the shaft of the pin, etc. is inserted into a hole provided in the joining base material, and the head of the pin, etc. is joined to the joining base material by projection welding, the head of the pin, etc. A triangular shape with a circumferential circle that is slightly larger than the outer circumferential circle of the head of the pin, etc., between the part and the joining base material, and whose center of gravity is the axis of the pin, etc. is the outer circumferential circle of the head of the pin, etc. A welded joint of a pin, etc., characterized in that a stepped portion having a cut-off shape and an axis orthogonal cross section is formed, and the head of the pin, etc. and a joining base material are joined by projection welding via the stepped portion. structure.