JPH0623544A - Back-bead welding method - Google Patents

Abstract

PURPOSE:To form the sound back-bead where no strict precision or the like is required and no residual slits exist, to facilitate formation of the excellent back-bead, and to improve the fatigue performance. CONSTITUTION:Back-bead parts 3, 4 are formed on the back side of the weld part of a first welding base metal 1 and on the back side of the groove of a second welding base metal 2 respectively by the bead-on-plate welding of the arc welding, and the back bead 6 is formed between the respective back- bead parts 3, 4 by abutting the end part on the groove back side of the second welding base metal 2 to the back bead part 3, or arranging the corresponding end part in the vicinity thereof, and then executing the welding from the front side of the groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back bead welding method.

[0002]

2. Description of the Related Art As a first conventional example relating to a backside bead welding method, there is JP-A-58-61992. In this first conventional example, as shown in FIG. 4, no backing material is used and the first and second welding base materials 51, 52 are used.
Each of the joint portions 53, 54 of the above is formed into a projection shape by processing, and by welding from the front surface 55 of the first welding base material 51, it is also melted into its back surface 56 to form a back bead. There is. This is because the workability is improved by eliminating the fishing and the back welding on the back, and good backside welding can be performed.

However, in the first conventional example, in order to form a favorable back bead, it is necessary to form, for example, projecting joint portions 53 and 54. This requires strict processing accuracy and assembling accuracy, and further severely requires control of welding conditions.

On the other hand, when the backing material is used, the above-mentioned strict precision is not required, but there is a problem in the joint performance due to the residual slits due to the presence of the backing material. In addition, the backing material needs to be installed with a certain degree of accuracy and a corresponding amount of work.

In order to solve the above-mentioned drawbacks, the applicant of the present application has filed the prior application, Japanese Patent Application No. 2-418825.
No. 1 proposes the following Uranami bead welding method.
In this second conventional example, as shown in FIGS. 5 and 6, the backing bead portion 62 is formed on the back surface side of the welding portion of the first welding member 61 by bead-on-plate welding by the consumable arc welding method. The groove back surface side end of the welding base material 63 is brought into contact with the backing bead portion 62 or is arranged in the vicinity thereof, and then welding is performed from the groove front surface side, whereby the backing bead portion 62 is Uranami bead 64 between the groove and the back side
Are formed. According to this method
It is possible to form a favorable back-bead bead without requiring strict precision as in the back-bead welding method of the first conventional example.

[0006]

However, in the case of the back bead welding method described above, even if the shape of the toe portion 65 on the side of the first welding base metal 61 can be welded to an optimum shape,
The shape of the toe portion 66 on the side of the second welding base metal 63 has a drawback that stress tends to be concentrated and the fatigue performance is inferior. This tendency is particularly noticeable in members such as steel columns and drums where the groove back surface is not processed after welding is completed.

The present invention has been made in order to solve the above-mentioned conventional drawbacks, and an object thereof is to form a sound backside bead which does not require strict accuracy and has no residual slit. It is an object of the present invention to provide a backside bead welding method which is capable of further facilitating the formation of a good backside bead and further improving the fatigue performance.

[0008]

Therefore, according to the backside bead welding method of the present invention, the back side of the welded portion of the first welding base metal and the second side of the second welding base metal are welded.
Back bead portions are formed on the groove back surface side of the welding base material by bead-on-plate welding by an arc welding method, and the groove back surface side end portion of the second welding base material is brought into contact with the back contact bead portion. Alternatively, the back bead is formed between the back bead portions by arranging them in the vicinity thereof or by welding from the groove surface side.

[0009]

In the above-mentioned backside bead welding method, since the backing bead portion is formed not only on one of the welding base materials but also on both welding base materials, the backside bead is prevented from melting through. The function as a backing material is further strengthened, and the back bead can be easily formed even if there is some variation in the route interval.

Before the temporary assembly, the welding can be carried out under welding conditions such that the toe portions 7 and 8 are optimally shaped, or the shaping can be performed. Fatigue performance can be improved even in a member whose back side is not processed. Moreover, in the above-mentioned back bead welding method, the back bead is formed between both back bead portions, but since the back bead portion can be regarded as integral with each base metal, no slit remains.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the back bead welding method of the present invention will be described in detail with reference to the drawings.
1 and 2 show an embodiment of the present invention. Figure 1
In the above, reference numeral 1 is a main plate, and 2 is a standing plate. The standing plate 2 is
A groove is processed on one end side thereof.

First, the backing bead portion 3 is formed on the back surface side of the main plate 1 by bead-on-plate welding by the arc welding method.
To form. Similarly, the backing bead portion 4 is formed on the groove back surface side of the standing plate 2. This welding is performed so that the shapes of both the toe portions 7 and 8 are smooth so that stress is not concentrated. Alternatively, after forming the backing bead portions 3 and 4, this portion may be shaped into the above-mentioned shape by an appropriate grinding means.
As the welding, any of consumable type and non-consumable type such as MIG welding, carbon dioxide arc welding, covered arc welding, and TIG welding can be selected. The welding posture is preferably downward welding in which the standing plate 2 is horizontally arranged, but it is not limited to this.

Next, the end portion 5 on the groove back surface side of the standing plate 2 is shown in FIG.
As described above, the back bead portion 3 is arranged at a position slightly to the left of the center (preferably 5 to 8 mm), and in this state, arc welding is performed from the groove surface side. As a result, as shown in FIG. 2, a back bead 6 is formed on the groove back surface side of the standing plate 2 including both back contact bead portions 3 and 4. In this case, it is preferable that the root gap is about 0 to 3 mm, and in some cases, a root surface of about 0 to 2 mm is provided.
Of course it is not limited to this.

According to the above-mentioned back bead welding method, the back bead portion acting as the backing material is formed not only on one welding base material but on both welding base materials. The burn-through can be prevented more strongly. Therefore, there may be some fluctuations in the route interval, and strict control of processing accuracy, assembly accuracy, and welding conditions is not required, and the formation of the back bead becomes easier. On the back side of the weld,
The slits that are generated when the conventional backing material is used do not remain. In addition, both toe parts 7, 8 before temporary assembly
It is possible to select welding conditions that can optimize the shape, or to shape the shape, so that the fatigue performance can be improved even for a member in which the groove back surface is not processed after welding is completed.

FIG. 3 shows a more specific embodiment. This was welded under the following conditions. That is, the back bead portions 3 and 4 have a welding voltage of 20V,
It was formed by a carbon dioxide arc welding method with a welding current of 150 A and a welding speed of 360 mm / min. In this case, the standing plate 2 has a plate thickness of 19 mm and a groove angle of 45 degrees. The distance between the center of the back bead 3 and the back of the groove is 5
Approximately 6 mm, both root gap and root surface are 0
Is. Uranami bead welding is performed by a downward carbon dioxide arc welding method with a welding voltage of 30 V, a welding current of 300 A, and a welding speed of 360 mm / min. According to this method, FIG.
As described above, it is possible to obtain a good welded joint without welding defects.

The welding posture in the back bead welding method is not limited to downward, and may be any posture, and the number of welding layers may be either single layer or multilayer. Further, the shape of the welded joint to which the above-mentioned welding method can be applied is not limited to those shown in FIGS. 1 and 2, and various shapes can be applied.

[0017]

As described above, according to the backside bead welding method of the present invention, the backside welding is performed while the backing bead portion integrally formed on both base materials has a function as the backing material. As a result, the gap allowance at the bead forming portion of the back wave becomes larger than that of the conventional one, while performing the good back wave welding without the residual slit. As a result, high precision in processing parts and assembling is not required as in the prior art, and the margin of weldable conditions is large, so that welding work efficiency can be improved.

Moreover, when a backing material is used, in a structure having a complicated shape, it is necessary to accurately shape and arrange the backing material along the complicated shape. In the method of the present invention, bead-on-plate welding is performed. Since it is only necessary to perform the welding, the welding work efficiency is also improved in this respect.

[Brief description of drawings]

FIG. 1 is an explanatory view of a state before welding of an embodiment of a backside bead welding method of the present invention.

FIG. 2 is an explanatory view of a state after welding according to an embodiment of the method of the present invention.

FIG. 3 is a micrograph showing a metal structure of a welded portion obtained by the method of the above embodiment.

FIG. 4 is a diagram showing a backside welded joint of a first conventional example.

FIG. 5 is an explanatory diagram of a state before welding in a second conventional example.

FIG. 6 is an explanatory diagram of a state after welding of a second conventional example.

[Explanation of symbols]

 1 1st welding base material 2 2nd welding base material 3 backing bead part 4 backing bead part 5 groove back side end 6 back bead 7 toe end 8 toe end

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masaki Tanaka 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Kawasaki Heavy Industries Ltd. Kobe factory (72) Hideo Kawahara Higashi-kawasaki, Chuo-ku, Kobe-shi, Hyogo 3-1, 1-1 Machi Kawasaki Heavy Industries Ltd. Kobe factory

Claims (1)

[Claims] 1. A backing bead portion is formed by bead-on-plate welding by an arc welding method on the back surface side of the welded portion of the first welding base material and the groove back surface side of the second welding base material, respectively.
Between the respective back bead portions by contacting the groove back surface side end portion of the second welding base material with the back contact bead portion or arranging in the vicinity thereof and then performing welding from the groove front surface side. A backside bead welding method, which comprises forming a backside bead on the bottom.