JPH041205B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is utilized in the technical field of welding fasteners used by being welded to objects, and includes a welding fastener having a triangular cross section on the weld joint surface side. The present invention relates to a welding fastener having a ring-shaped protrusion, which has been improved to improve welding results.

(Prior Art) Fasteners that are used by pressing the fastener against an object and welding the two are well known.
On the other hand, so-called projection welding is also well known, in which a protrusion is provided on a part of the joint surfaces to be welded, the welding surfaces are pressed against each other, and a potential difference is applied therebetween to weld at the protrusion.

Therefore, the inventor came up with the idea of providing a ring-shaped protrusion on the weld joint surface of the fastener and performing welding at this part.
This method is known from Japanese Utility Model Application Publication No. 49-49358. Of course, the fastener disclosed in this Japanese Utility Model Publication No. 49-49358 is not intended for welding, but for preventing loosening of the fastener. However, by simply providing such a ring-shaped projection, it is not possible to obtain a fully satisfactory welding result.

That is, when a bolt a as a fastener, as shown in FIG. When the plate f, which is the object to be welded, is pressed against the joint surface d, a potential difference is applied between the plate f and the bolt a, and projection welding is performed. First, the ring-shaped protrusion e melts, and then the welding occurs. The entire surface of the surface d is in contact with the surface of the plate f, and the welding current is dispersed at this equitangential surface, resulting in insufficient welding. Furthermore, since the outer edge of the head b cannot be sufficiently welded, there is a problem in that it leads to the generation of rust stains, which causes defects when the outside is electrodeposited or painted.

(Object of the invention) In this invention, the above-mentioned problems can be solved. The object is to provide an improved welding fastener.

(Structure of the Invention) The structure of the invention is such that a protrusion having a substantially triangular cross section is provided in a ring shape on the welded joint surface, and the step between the tip of the ring-shaped protrusion and the outer flange surface is the height of the protrusion. The cross-sectional shape of the ring-shaped protrusion is set to be smaller than the step between the tip and the inner flange surface, and the inclination angle of the outer surface is smaller than the inclination angle of the inner surface with respect to a line parallel to the axis passing through the tip of the protrusion. This relates to a welding fastener characterized by being large.

(Embodiment) Next, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4.

1 is a steel bolt as a welding fastener according to an embodiment of the present invention. The bolt 1 consists of a head 2 and a threaded portion 3. The threaded portion 3 side of the head 2 is configured as a welding joint surface 4, and a projection 5 having a triangular cross section is provided on this welding joint surface 4 so as to integrally go around in a ring shape.

The outer flange surface 4a of the projection 5 on the welding joint surface 4 is set higher than the inner flange surface 4b by an amount H as shown in the figure. That is, the protrusion 5
The step between the tip and the outer flange surface 4a is the protrusion 5.
The height difference is set to be smaller than the level difference between the tip of the flange and the inner flange surface 4b. In addition, in the cross-sectional shape of the protrusion 5, the inclination angle θa of the outer surface 5a with respect to a line 1 parallel to the center line Lc passing through the tip of the protrusion 5 is larger than the same inclination angle θb of the inner surface 5b. In this embodiment, the inclination angles are θa of 40 degrees and θb of 30 degrees.

The threaded portion 3 is inserted into the attachment hole 6a drilled in the steel plate 6 of the object to be welded to the bolt 1 constructed as described above, such as a steel plate 6 of a frame, and the ring-shaped protrusion 5 is brought into contact with the steel plate 6. let Then, an electrode (not shown) of a welding power source (not shown) is connected to the bolt 1 and the steel plate 6, and these are pressed together.
Then, the contact portion between the ring-shaped protrusion 5 and the steel plate 6 is heated by Joule heat due to contact resistance, and the ring-shaped protrusion 5 is melted. At this time,
Since the inclination angle θa of the outer surface 5a of the ring-shaped protrusion 5 is smaller than the inclination angle θb of the inner surface 5b, the amount of penetration of the outer surface 5a is larger than that of the inner surface 5b, and therefore the ring-shaped protrusion Most of the weld metal M of No. 5 flows toward the outer surface 5a (as shown in FIG. 3). As the welding progresses further, the steel plate 6 and the outer flange surface 4a come into contact, and this portion is slightly melted and welded, completing projection welding.

In addition to the embodiments described above, this invention can also be modified as described below.

(a) In addition to bolts, the fasteners may be of other known constructions such as nuts.

(b) The cross-sectional shape of the ring-shaped protrusion may be triangular or other almost triangular shapes, and the inclination of the inner and outer sides of this cross-sectional shape is such that the inclination angle of the outer surface is smaller than the inclination angle of the inner surface. It may be set to an appropriate value within the range of increasing the value.

The experimental results of the embodiment shown in FIG. 1 and a comparative example are shown in FIGS. 6 and below. That is, for the purpose of this invention, which is to obtain a small amount of penetration over the entire outer periphery in order to prevent the generation of rust liquid, setting the angle of the protrusion is important.
That is, as in the comparative example shown in FIGS. 6 and 7, the molten metal M flows into the side where the protrusion inclination angle θa is larger, and from the perspective of the intention of the present invention, the molten metal M flows into the protrusion as shown in FIG. The outer surface inclination angle θa needs to be larger than the inner surface inclination angle θb.

(Effects of the Invention) The effects of the invention described above are listed below.

(1) A ring-shaped protrusion with a nearly triangular cross section is provided on the weld joint surface, and the inclination angle of the outer surface is larger than the inclination angle of the inner surface. Therefore, penetration during projection welding is suppressed by the inner side of the ring-shaped protrusion. Since the outer periphery of the ring-shaped protrusion is mainly melted, the rust prevention effect on the outer surface is improved.

(2) Furthermore, since the outer flange surface of the ring-shaped protrusion is set higher than the inner flange surface, after the ring-shaped protrusion has melted, the outer flange surface will come into contact with the welding object, and some melting will occur. Deep grooves are not formed on the outer periphery of the welded area, and electrodeposition during electroplating is sufficient, suppressing the generation of rust stains. In addition, reliable airtightness can be expected even in areas that require secrecy.

(3) Since a ring-shaped protrusion is provided on the outside of the welding joint surface to form a flange surface, the welding current is concentrated on this protrusion, eliminating reactive current and saving energy. The life of the mold tool will also be extended. Further, since the protrusion has a flange surface on the outside, the phenomenon of melting of the side surface 2a does not occur when the protrusion is completely melted.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a partial longitudinal sectional view, FIG. 2 is a view taken in the direction of the arrow in FIG. 1, and FIGS. FIG. FIG. 5 is a partially longitudinal side view for comparison with the present invention, FIGS. 6 and 7 are cross-sectional views of fasteners of an experimental example for comparison with the embodiment of the present invention, and FIG. 8 is an embodiment of the present invention. FIG. 1... Bolt (welding fastener), 4... Welding joint surface, 4a... Outer flange surface, 4b... Inner flange surface, 5... Projection, 6... Steel plate (object), θa... ...Outer surface inclination angle, θb...Inner surface inclination angle.

Claims (1)

[Claims] 1. In a welding fastener that is used by being welded to an object, a protrusion with an approximately triangular cross section is provided in a ring shape on the welding joint surface, and the tip of the ring-shaped protrusion and the outer flange surface The step difference is set to be smaller than the step difference between the tip of the projection and the inner flange surface, and the cross-sectional shape of the ring-shaped projection has an inclination angle of the outer surface of the ring-shaped projection with respect to a line parallel to the axis passing through the tip of the projection. A welding fastener characterized in that the angle of inclination is greater than the angle of inclination of the side surface.