JP2005138165A - Welding stud - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding stud which can enhance the tensile fatigue strength of its stem by preventing separation between the stem of the stud and a weld reinforced portion. <P>SOLUTION: In the welding stud of which the front end 11 of the stem 1 is welded to a base metal 2, a bumpy pattern 3 is formed on the outer circumferential face 12 of the front end of the stem. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a welding stud used for stud welding, and more particularly to a welding stud that can eliminate the separation between a stud shaft portion and a weld surplus portion and improve the axial tensile fatigue strength.

For example, when a headed stud is used as a live load composite slip stopper, the fatigue strength of the stud becomes a critical value in design.
When a conventional headed stud is welded and observed with a focus on the root of the weld, the stud shaft part and the weld surplus part are separated, and the separation is considered to have an adverse effect on the fatigue strength.

In the stud welding process, when the main arc occurs, the stud tip surface and the steel plate side are melted by arc heat, and then the stud plunges into the steel plate melting part, but the stud tip surface melts into a hemispherical shape, and the pinch effect ( Maintained by welding phenomenon).
At this time, the shaft portion on the upper side of the hemispherical melted portion is not melted in a solid state, and the cooled shaft portion in this solid state directly projects into the steel plate melted portion. Separation occurs between them, and the shaft part and the weld surplus part are separated.

  In view of the problems of the above-described conventional welding studs, the present invention provides a welding stud that can eliminate the separation between the stud shaft portion and the weld surplus portion and improve the fatigue strength of the shaft tension. Objective.

  In order to achieve the above object, a welding stud according to the present invention is characterized in that, in a welding stud for welding a tip end surface of a shaft portion to a base material, an uneven pattern is formed on the outer peripheral surface of the tip portion of the shaft portion.

  In this case, the uneven pattern can be formed in a knurled pattern.

  According to the welding stud of the present invention, in the welding stud that welds the tip end surface of the shaft portion to the base material, an uneven pattern is formed on the outer peripheral surface of the tip end portion of the shaft portion. When the metal enters the recess and the metal is cooled and fixed, a weld surplus portion is formed, and this unevenness engages and fits with the weld surplus portion, thereby separating the stud shaft portion from the weld surplus portion. Can be eliminated and the fatigue strength of axial tension can be improved.

  In this case, by forming the concavo-convex pattern in a knurled pattern, the concavo-convex pattern can be formed deeply and uniformly, and the adhesion of the molten metal can be enhanced.

  Hereinafter, embodiments of the weld stud of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the welding stud of the present invention.
This welding stud is a stud with a head that stud welds the tip end surface 11 of the shaft portion 1 to the base material 2, and a knurled fine concavo-convex pattern 3 is cold-forged on the outer peripheral surface 12 of the tip portion 1. It is formed by.
In this embodiment, the knurled uneven pattern 3 is formed in an eyelet shape having an interval of about 1.5 to 2.5 mm and a depth of about 1 mm, but other dimensions and shapes may be adopted. The knurled eyes can be formed in a flat shape.
Moreover, as shown in FIG.1 (b), it is desirable to form the uneven | corrugated pattern 3 of this knurled eyes etc. in the range which the weld surplus part 4 after welding reaches at least.

In the welding stud of this example and the conventional welding stud shown in FIG. 2, a tensile load is repeatedly applied to the stud welded portion, and a fatigue curve of the welded portion fatigue strength: tensile stress (Δσ) −number of fractures (N) is obtained. It was.
As a reference comparison of fatigue strength, based on the results of this test, the steel structure association of Japan: Fatigue design guidelines for steel structures “fatigue design curve: Δσ-N” is compared with the strength grade.
As test materials, both studs were headed stud φ19, and the material thereof was JISB-1198 standard product. Moreover, the steel plate used as a base material has a dimension of t19 × 150 × 150, and the material is SS400.
The welding method was a power arc stud welding method, and the welding position was such that the stud was welded to the center of the steel plate.

The fatigue test method was carried out in accordance with Japan Steel Structure Association: Fatigue design guideline for steel structures “Fatigue design curve: Δσ−N”.
Using a fatigue testing machine (dynamic servo: FLC10), the stud welding shaft and steel plate are fixed to the chuck, and a tensile load is repeatedly applied based on the longitudinal direction of the stud shaft, and tensile stress (Δσ)-number of fractures ( N). A regression equation was derived from the obtained data by the method of least squares.

  The regression equation and test data are shown in Table 1 below.

  In the conventional welding stud, as shown in FIG. 2 (b), there is a separation 5 between the shaft portion 1 of the stud and the welding surplus portion 4, and the fatigue failure leaves all the welding surplus portion 4. The crack with the separated tip along the shaft portion 1 of the stud as a fulcrum developed along the heat affected zone 6 of the shaft portion of the stud.

On the other hand, since the welding stud of the present embodiment forms the concavo-convex pattern 3 on the outer peripheral surface 12 of the tip portion of the shaft portion 1, as shown in FIG. In this recess, the metal is cooled and fixed and the weld surplus portion 4 is formed, and this unevenness engages and fits with the weld surplus portion 4, so that the shaft portion 1 of the stud and the weld surplus The separation from the portion 4 was eliminated, and the fatigue strength of the axial tension could be improved.
As a result, the fatigue failure of the weld stud of the present example was developed along the heat-affected zone 7 of the base material 2 as shown in FIG.

  As mentioned above, although the welding stud of this invention was demonstrated based on the Example, this invention is not limited to the structure described in the said Example, A structure can be changed suitably in the range which does not deviate from the meaning. it can.

  Since the weld stud of the present invention has the characteristics of eliminating the separation between the stud shaft and the weld overlay and improving the fatigue strength of the shaft tension, it should be used suitably for stud welding applications. Can do.

One Example of the welding stud of this invention is shown, (a) is the front view, (b) is an expanded sectional view of a welding part. The conventional welding stud is shown, (a) is the front view, (b) is an expanded sectional view of a welding part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft part 11 Tip surface 12 Tip part outer peripheral surface 2 Base material 3 Concave and convex pattern 4 Weld surfacing part 5 Separation 6 Heat-affected part of shaft part 7

Claims (2)

  A welding stud for welding a distal end surface of a shaft portion to a base material, wherein a concave and convex pattern is formed on an outer peripheral surface of the distal end portion of the shaft portion.   The welding stud according to claim 1, wherein the uneven pattern is formed in a knurled pattern.

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