JPS5992167A - One-side welding method - Google Patents

Abstract

PURPOSE:To improve resistance to fatigue in a one-side welding method wherein the 1st member and the 2nd member are placed oppositely each other to form a space part between the opposed ends thereof and said space part is welded from one side face by curving at least one of the opposed ends of the 1st and 2nd members so as to converge the same toward the other end face. CONSTITUTION:The opposed ends 1', 2'' of the 1st and 2nd members 1, 2 are curved smoothly downward so as to be made convergent and the end faces 1'a, 2'a are pressed to a backing plate 3 to form a space part 4. The plate 3 is tack welded (a) to the 2nd member 2 from the part 4 to weld (b) the part 4. Since the ends 1', 2' of the members 1, 2 are curved 1b, 2b, the stress concentration in the weld zone that arises on acting of repetitive load is lessened and the weld zone is prevented from cracking.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is designed to butt two members together and weld them together on one side in order to manufacture box-shaped structures for construction machines used under severe load conditions such as bulldozers and power shovels. It's about how to do it.

Conventionally, as this type of butt single-sided welding method, as shown in FIG. The second members 1.degree. A method of abutting the back plate 3 across the back surface of the second member 1.2 and welding the space 4 between the opposing end faces from the front side, as shown in FIG. bending part 1
The method of integrally forming α and welding, as shown in Figure 3,
A method in which one end of the first member 1 is made oblique and has the same thickness as the second member 2, and a back plate 3 is temporarily attached and welded to the back surface of the first member 1, as shown in FIG. A method in which the first member 1 is made vertically long and the end surface 2α of the second member 2 is made oblique to form a space, and this space is welded.As shown in FIG. A method is known in which the attachment is welded, the second member 2 is brought into contact with the back plate 3 to form a space, and this space is welded.

However, with any welding method, when repeated loads are applied, large stress concentrations occur in the welded part.
Since a crack occurs in the welded part from the crack starting point A, the fatigue strength f becomes weak.

For this reason, conventionally the plate thickness t has been increased to reduce the generated stress, but this increases the weight of the entire structure fabricated by welding, which increases costs, and when installed on the car body. This causes problems such as the vehicle body being unbalanced and the vehicle stability becoming worse.

The present invention has been made in view of the above circumstances, and its purpose is to provide a single-sided welding method that can increase fatigue strength without increasing weight.

Embodiments of the present invention will be explained below with reference to FIG. 6 and subsequent figures.

FIG. 6 shows a welding method corresponding to the conventional welding method shown in FIG. Opposite ends 1', 2 of second members 1, 2
' is smoothly curved downward so as to be tapered, and the tip surfaces 1'α and 2'α are brought into contact with the back plate 3 to form a space 4, and the back plate 3 is moved through the space 4 to form a space 4. Temporary attachment to 2 parts 2 is welded (a)
B. Weld the space 4 (B).

As a result, the first. Since the opposite ends of the second members 1 and 2 (welded parts N+/, 2F) have curved surfaces 1b and 2b, stress concentration in the welded parts is reduced when repeated loads are applied. Cracks α are less likely to occur, and fatigue strength can be improved without increasing the plate thickness t.

Figures 7, 8, 9, and 10 show welding methods corresponding to the conventional welding methods shown in Figures 2, 3, 4, and 5, respectively. , respectively second member 2
The opposite end 2' of the tube is curved downward so as to be tapered. Note that the other parts are the same as the conventional one, so the explanation will be omitted.

In each welding method, without increasing the plate thickness t,
Can increase fatigue strength.

For example, according to the welding method shown in FIG. 7, as shown in FIG. 11, the thickness of the first member 1 is 1. Also, since the throat thickness is larger than the thickness t2 of the second member 2, the stress at the point where fatigue cracks occur can be kept low. In addition, since the tip of member 2 is curved so that it is tapered, a large volume can be removed, and fatigue failure at the R stop part (point B) of member 2 can be prevented. Therefore, if repeated loads are applied to the main body. Increased fatigue strength! Become stronger.

Note that the opposing ends t! of members 1 and 2! In order to curve 2F so that it becomes tapered, in the case of a thin plate, as shown in Fig. 12, it is sufficient to cut it with a die 10 and edges 11 and curve it at the same time. In this case, it is sufficient to cut with a fixed blade 12 and a movable blade 13 as shown in FIG. 13, and then curve the cut end with a die 14 and a punch 15 as shown in FIG. In the case of a thick plate, as shown in FIG. 14, the end part is cut diagonally by gas cutting, etc., and the cut part is bent with a die 16 and a punch 17, as shown in FIG. good.

In addition, welded by the conventional welding method shown in Fig. 3,
When a specimen welded by the welding method according to the present invention shown in FIG. 8 was subjected to a bioscillatory υ plane bending fatigue test, the results shown in FIG. 15 were obtained.

As a result, it can be seen that those welded by the welding method according to the present invention have high fatigue strength.

In addition, in FIG. 15, white circles are cases where the welding method according to the present invention is used, and black circles are cases where the conventional welding method is used.

According to the welding method of the present invention, the stress concentration at the crack starting point can be reduced without increasing the plate thickness of the member to be welded, and the fatigue strength can be increased without increasing the weight.

[Brief explanation of the drawing]

Figures 1, 2, 3, 4 and 5 are explanatory diagrams of conventional examples, and Figures 6, 7, 8, 8189, and 10 are illustrations of different examples of the present invention. Explanatory diagram showing an example, No. 11
The figure is a detailed explanatory diagram of welding by the welding method shown in FIG. 7, and FIG. 12. Figures 13 and 14 show the ends of the members +! FIG. 15, which is an explanatory diagram of the cleavage method, is a diagram showing the results of a bidirectional plane bending fatigue test for welding by the conventional welding method and welding by the welding method according to the present invention. 1.2 is the first. The second member 4 is a space. Figure 1 Figure 2 Figure 3 Figure 6 Figure 8 Figure 9

Claims (1)

[Claims] In the single-sided welding method, the first member and the second member are opposed to each other, a space is formed between the opposing ends, and this space is welded from one side. A single-sided welding method characterized in that at least one opposing end of the second member is curved toward the other side so as to be tapered.