JPS6325018Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to welded joints for metal materials that are relatively susceptible to cracking, particularly for metal cylindrical bodies (hollow or solid).
The present invention relates to a welded joint in which a metal support is inserted into a metal support having a hole that fits into the metal support, and arc welding is performed between the periphery of one end of the cylindrical body and the periphery of the support hole.

Among metal materials, high carbon steel is generally used when particularly high strength is required. However, high carbon steel is highly susceptible to cracking, and when welding it, defects are likely to occur in the weld. In order to prevent this, preheating treatment and post-heating treatment must be performed before and after welding. In addition, depending on the shape of the article to be welded, the heat capacity at the welding location may differ from each other, but if welding locations with different heat capacities under the same conditions, the shape of the welded joint will be uneven, resulting in a product with the desired shape. may not be obtained.

The purpose of the present invention is to prevent defects from occurring in the welded part even without preheating and post-heat treatment when welding a metal cylindrical body as described above to a support, and to prevent defects from occurring in the welded part even if there is no preheating or post-heat treatment. To provide a welded joint that has a uniform shape even when

Hereinafter, the present invention will be described in detail with reference to the drawings. The embodiments described below relate to welding the knuckle portion of a shock absorber for an automobile.

1 is a plan view of the knuckle portion of the shock absorber, and FIG. 2 is a sectional view taken along line XX in FIG. 1. In the figure, 1 is a knuckle (support body) made of high carbon steel with high crack susceptibility, 2 is a shock absorber outer cylinder (cylindrical body) made of steel,
Reference numeral 3 designates a cover material at the end of the shock absorber made of steel. As is well known, the knuckle 1 has a hole 4 into which the shock absorber outer cylinder 2 is fitted, and after inserting the shock absorber outer cylinder 2 into this hole 4, the surroundings of the cover member 3 and the shock absorber outer cylinder are inserted. 2
Arc welding is simultaneously performed between the periphery of the end of the knuckle 1 and the periphery of the hole 4 of the knuckle 1, and these three parts are fixed together. The thickness of the shock absorber outer cylinder 2 is uniform in the circumferential direction, and therefore the heat capacity of the end portion to be welded is also uniform in the circumferential direction. The knuckle 1 has an arm portion 5 (Fig. 2), which is symmetrical with respect to the cross section X-X in Fig. 1, but the cross section Y-
It is not symmetrical with respect to Y. That is, when welding around the hole 4 of the knuckle 1, the cross section Y-
The material heat capacity differs greatly on the left and right sides of Y, and A
The area shown by has a high heat capacity, and the other areas have a relatively low heat capacity.

When the mass of the part to be welded is uneven like this, conventionally, welding defects (cracks, etc.) are likely to occur in areas with poor welding conditions, that is, areas with high material heat capacity, so preheating treatment is used as a countermeasure. They performed post-heat treatment and set arc welding conditions (welding time, etc.). For this reason, welding conditions become excessive in areas with low heat capacity, resulting in wasted heat and welding wire.

Therefore, in the present invention, in the material to be welded (around the hole 4 of the nutcle 1), an area A having a high heat capacity is
A counterbore 6 is provided in the counterbore 6 so that the arc welding at the counterbore 6 portion is as close as possible from the fillet weld joint to the butt weld joint. Areas with low heat capacity other than area A are fillet weld joints.

Fig. 3 is an enlarged sectional view of a welding point according to the present invention in which a counterbore 6 is provided, Fig. 4 is a sectional view of a part corresponding to Fig. 2 in a conventional example without a counterbore, The figure is an enlarged sectional view of a conventional welding location. In Figures 3 and 5, 10 and 10' are weld beads, W and W' are the amount of penetration in the lateral direction of the knuckle, H and H' are the depth of penetration in the downward direction of the knuckle, α, α ′ is the penetration angle. In the present invention, the knuckle 1 is provided with a counterbore 6, so that the welding points of the knuckle 1, the shock absorber 2, and the lid member 3 are either on the same plane or with a slight difference in level as shown in Fig. 3. The arc welding bead is poured from above. Therefore, the welded joint has a shape that approaches a butt weld from a fillet weld, as shown in Figure 3, and a W shape as shown in Figure 6.
>W', H>H', and α>α', the welded joint of the present invention (Fig. 3) has a larger weld bead penetration than the conventional welded joint (Fig. 5). is a graph showing W (W'), H (H'), and α (α'). 10 welds each as shown in Figures 3 and 5.
The number shown at the top is the maximum value, the number shown in the middle is the average value, and the number shown at the bottom is the minimum value. The welding conditions are such that the welding target is centered in the direction shown by arrow P in Figures 3 and 5, the welding angle is 50°, and the product is set in a position such that the direction of arrow P is perpendicular. I did it.

FIG. 7 is a graph showing welding conditions (generated heat amount Q) for the welded joint of the present invention (FIG. 3) and the conventional welded joint (FIG. 5). In this graph, B is the range of good welding conditions in the case of the present invention,
B′ is the range of good welding conditions according to the conventional example, ×××
△△△ is a range where welding defects (such as cracks) occur, and △△△ is a range where there are no welding defects but the appearance deteriorates. The welding conditions (generated heat Q) are Q = 0.24VIT/
1000 (kcal), V is the arc voltage (volt), I is the welding current (ampere), and T is the welding time (seconds). In this way, according to the present invention, the critical point of welding conditions at which defects occur can be significantly lowered.
It becomes possible to weld the area of the large A (Fig. 1) of the welding area and the other general area (360°-A) under the same conditions. This is because by using a butt welded joint as shown in Fig. 3, the heat input to the knuckle 1 can be increased, and the cooling rate can be slowed down and the same cooling rate as in the general area can be obtained. This also eliminates the need for post-heat treatment. Note that the welding locations of the knuckle 1, the shock absorber 2, and the lid member 3 do not have to be on the same plane.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the knuckle portion of the shock absorber, Fig. 2 is a sectional view taken along line XX in Fig. 1, Fig. 3 is an enlarged sectional view of the welded joint according to the present invention, and Fig. 4 is a conventional example. Fig. 5 is an enlarged sectional view of a conventional welded joint, Fig. 6 is a graph comparing the amount of weld bead penetration, and Fig. 7 is a comparison of welding conditions. It is a graph. 1... Metal support (knuckle), 2... Metal cylindrical body (shock absorber outer cylinder), 4... Hole, 6
...Counterbore, A...A region with high material heat capacity.

Claims (1)

[Scope of utility model registration request] When a metal cylinder 2 is inserted into a metal support 1 having a hole 4 that fits therein, and arc welding is performed between the circumference of one end of the cylinder and the circumference of the hole, one end of the cylinder has a heat capacity. are substantially equal in the circumferential direction, and on the other hand, when the metal support has different material heat capacity with respect to the hole, a counterbore 6 is provided around the hole in the region A with high heat capacity to approximate butt welding, and another region with low heat capacity is welded. is a welded joint characterized by a fillet weld.