JPS5913950B2 - Welding end tab - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an end tab used in arc welding, especially gas shielded arc welding.

In Fig. 1, 1 and 2 are base materials to be welded, 3 is a groove provided in the part to be welded between the two base materials, 4 is a back plate that is in contact with the lower surface of the part to be welded, and 5 is the welded part. This is an end tab (end plate) that abuts both end faces of the base metal of the weld, that is, the joint.

End tabs are used to minimize the welding excess length at the end of the weld bead. Conventionally, a small block made of the same material as the base metal is used, and it is temporarily welded to the base metal or back plate. However, since preparation and installation, as well as removal and finishing after welding, requires time and effort, in recent years fire-resistant solid end tabs made of hardened welding flux, etc., have been replacing these metal tabs. It was proposed and started to be used.

The present invention relates to an improvement of this type of fire-resistant solid end tab,
During production, water glass is mixed with refractory powder, molded into a desired shape, and solidified in a CO2 gas atmosphere, making it extremely easy to produce.

Further, since the end tab of the present invention generates CO2 gas in the welding arc atmosphere, oxidation of the base metal joint end face is prevented, and it is extremely effective in preventing the occurrence of welding defects such as blowholes. This is because carbonate is produced when the tab is solidified by CO2 gas, and CO2 gas is generated from the portion where the tab is melted by the welding arc, exerting the effect of shielding the end face. '0 In the present invention, the particle size structure of the refractory is finer than 48 mesh, and smaller than 270 mesh is 50.
% or less is because if particles coarser than 48 mesh are mixed in, the heat-receiving surface of the end tab will not be flat and the appearance will be rough.
This is because if particles finer than zero mesh exceed 50%, the arc becomes unstable during welding, and slag increases, causing defects such as slag entrainment.

The refractories used in the end tabs of the present invention include molten and non-molten welding fluxes, raw materials for welding, slag powder produced by submerged arc welding, ceramic powder, etc., but the particle size structure of the refractory In addition, the type of refractory, compounding composition, molding density, etc. have a great influence on obtaining defect-free welds, especially defect-free joints at the bead ends, so it is important to confirm this through actual experiments. It is better to decide whether to adopt or not and the combination. For example, the melting point is 2
Tabs whose main component is a high-melting refractory with a melting point of 1,000°C tend to have poor adhesion between each layer and tend to undercut, and when using a low-melting refractory with a melting point of 1,000°C, welding arc This must be avoided because the melting of the solid flux stub due to heat becomes extremely large and the extra length at the bead end becomes large. The melting point referred to herein is the melting point measured by the button test method.

The amount of water glass mixed into the refractory raw material is 5 to 2 of the weight of the raw material.
0%, usually around 15%.

While stirring the dry blended refractory raw materials, water glass is mixed therein and molded. A mold may be used for molding if necessary. This is a CO2 gas atmosphere. Solidify and dry in the air. The shape of the end tab of the present invention is not particularly limited.

For example, when the main component is a high melting point refractory, as shown in Figure 2, there is a gap to allow excess welding at the joint end. It can be made into a shape with . Furthermore, when the main component is a low melting point refractory, no voids are required and the heat receiving surface 6 may be a simple flat surface, so a rectangular block as shown in FIG. 3 may be adopted. Next, examples will be described.

Example 1 The particle size structure of Formulation Example 1 after dry blending is as shown in Table 1.

Add 15% water glass to each raw material in the above formulation examples I and ll.
% (wt%) was mixed.

Each raw material mixed with water glass was put into a rectangular mold, solidified with CO2 gas and dried according to the well-known "mold CO2 method" to obtain an end tab having the shape shown in FIG. 3.

Their apparent densities and melting points are shown in Table 2.
FIG. 4 is a perspective view showing an example of how the end tab of the present invention is used, in which 1 and 2 are base materials, 3 is a groove, 4 is a back plate, and 5'
is the end tab of the present invention.

The end tab 5' is supported in contact with the side surfaces of the base material at both ends of the groove by a threaded rod 10 screwed into a handle 9 having magnets 8, 8 fixed to the leg ends. Since this end tab 5' is lightweight, it can be attached very easily by such means, and since the bead is not welded, it is also very easy to remove it after welding is completed. The end tab of the present invention listed in Example 1 was installed as shown in Fig. 4, and the base material was 25 mm thick SM.
5OA material was gas-shielded arc welded under the welding conditions shown in Table 3. After welding, the end tab was removed and the bead end was inspected, and the protrusion at the bead end was at its maximum in Formulation Example 1.
The 2.5 mml formulation example is Max3. Omm, the formulation example is Max2. The appearance of the bead ends was good, with no defects such as blowholes or slag entrainment, and no defects were found in all the welded parts.

Example 2 Using a refractory with the same composition as the refractory blending example in Example 1, the particle size structure after dry blending and stirring was changed as shown in Table 4,
In each case, 15% (weight %) of water glass was mixed.

End tabs were obtained using raw materials having particle size structures A, B, and C shown in Table 4 in the same manner as in Example 1.

The apparent density and melting point of this are shown in Table 5. End tabs having the above grain size configurations A, B, and C were gas-shielded arc welded under the same conditions as in Example 1. The protrusion of the bead end after welding was about 2.5 max for grain size compositions A, B, and C, the external sharpness was good, and no defects such as slag entrainment were observed, similar to Example 1. No defects were found in all the welded parts, and an excellent joint was obtained. The end tab of the present invention is inexpensive and easy to manufacture, and can be easily and quickly attached, removed, and finished during welding, thereby significantly contributing to increasing the efficiency of welding operations.

In addition, since the end tab of the present invention is made by mixing water glass and solidifying it with CO2 gas, the heat receiving surface has a relatively low density, so even if a low melting point refractory is used, less slag is generated during welding. This not only prevents defects such as slag entrainment, but also releases CO2 gas from the tab itself, which has the same effect as the arc atmosphere of CO2 gas arc welding, and promotes shielding between the end tab and the base metal joint end face. However, it also has the effect of preventing the occurrence of defects such as blowholes and providing a sound joint.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the general usage of the end tab. FIGS. 2 and 3 are perspective views showing examples of the shape of the end tab, and FIG. 4 is a perspective view showing an example of how the end tab of the present invention is used. Explanation of symbols in the drawings, 1, 2... Base material, 3... Bevel, 4... Back plate, 5, 51
... End tab, 6 ... Heat receiving surface of end tab, 7 ... Gap provided in heat receiving surface, 8 ...
...Magnet, 9...Handle, 10...
・Screw rod.

Claims (1)

[Claims] 1 5 is finer than 48 mesh and smaller than 270 mesh
5 to 20% (by weight) of water glass is mixed with a refractory with a particle size composition of 0% or less, molded into a desired shape, and then CO_2
An end tab for welding that is solidified with gas.