JPS59118282A - Flash butt welding method - Google Patents

Abstract

PURPOSE:To shield the periphery in a heated part and to prevent the oxidation of the alloy components in materials to be welded in the stage of flash butt welding of plate material by sticking a material which generates gas except oxygen near the butt part of the materials to be welded. CONSTITUTION:A pair of plate-shaped materials W, W' to be welded are clamped by electrodes 1, 2. A material 3 which generates gas except oxygen by the effect of heat during welding is stuck on the top and bottom surfaces near the butt patt of the materials W, W'. The material 3 is selected from (a) a carbon polymer, org. compd. or org. silicon compd. (b) zinc or zinc powder-contg. material, and (c) and alloy or intermetallic compd. contg. calcium or magnesium or material contg. the same. If the materials are subjected to flash butt welding in this state, the material 3 is easily evaporated 4 to vapor and the periphery of the heated part is shielded from the atm. by the vapor pressure thereof. The weld zone is therefore kept free from oxide remaining therein.

Description

[Detailed Description of the Invention] The present invention is a method of performing flash butt welding by butting plate-shaped materials to be welded, specifically steel plates, etc., in which oxides remain in the welded part and cracks are likely to occur. The present invention relates to a flash butt welding method that effectively prevents this and improves welding quality.

The flash butt welding method is a butt welding method that utilizes the Joule heat generated by the current flowing through the contact portion when the butt end surfaces of the materials to be welded come into contact, and the arc heat generated after the contact portion melts and scatters.

Hereinafter, the principle of the flash butt welding method will be explained in some detail based on FIGS. 1(a), 1(b), . First, as shown in (a), a pair of plate-shaped materials to be welded (steel plates) w and w' that are butted together are connected to a pair of upper and lower electrodes 1 attached to a fixed platen (not shown).
After clamping with a pair of upper and lower electrodes 2 attached to a movable platen (not shown), a voltage is applied between both electrodes 1 and 2, and the movable platen is advanced to move the workpiece to be welded clamped to the electrodes 2. The material W' is advanced as shown in (b). Then, the butt end surfaces of the welded materials w and w' approach each other (c)
When there is slight contact as shown in Figure 1, a short circuit current flows through the contact area, and the contact area melts and scatters due to the Joule heat generated in that area. Generally, the power supply circuit of a welding machine includes an inductance, so after the contact portion scatters, an arc is generated at that point. Due to the generation of this arc, the molten metal flashes and scatters from the end surfaces of the welded materials w and w', causing the welded materials W to become welded.

Electrical contact between W' is broken. During this time, the movable platen continues to move forward, so after a short period of time, the end faces come into contact again, and after that contact portion melts and scatters, an arc is generated, and the same process as described above is repeated. In this way, the above-mentioned process is repeated many times over the entire abutting surfaces of the welded materials w and w', thereby increasing the temperature near the end faces and forming a molten layer on the entire end face surface (flash). process). After that, as shown in (d), the platens on both sides are rapidly moved to stop the flash from occurring, and the butt portions are welded for a predetermined period of time with the entire end surfaces of the welded materials w and w' in close contact. When pressed, (e)
Welding is completed by upsetting as shown in (upsetting process).

In the above-mentioned upsetting process, if the oxides of manganese, silicon, chromium, etc., which are alloy components of the welded material, remain in the weld without being extruded, the oxides will be damaged when the weld is subjected to tensile stress or bending stress. Remaining of such oxides must be avoided as much as possible since it may cause cracking.

In order to avoid this, it is effective to some extent to select welding conditions appropriately, but when welding materials made of specific materials, such as steel with a high silicon content, it is only necessary to select welding conditions appropriately. Therefore, it is extremely difficult to avoid the oxide remaining in the welded portion.

In addition, a method has been proposed in which the area around the weld is shielded using an inert gas to prevent the oxides from remaining in the weld, but this method causes extremely large losses and also causes spatter caused by flash. Since this occurs frequently, there are problems in workability and operability, and it is difficult to implement.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a simple method for shielding a weld zone to avoid the oxide remaining in the weld zone.

In the flash butt welding method according to the present invention, when flash butt welding is performed by butting plate-shaped materials to be welded, (a) a carbon polymer, an organic compound, or Organosilicon compound (b) Zinc or zinc powder-containing substance (c) An alloy containing calcium or magnesium, an intermetallic compound, or a substance containing it is deposited and then welded.

The method of the present invention will be explained below based on the drawings showing its implementation state. FIGS. 2 and 3 are schematic diagrams showing the implementation state of the method of the present invention, with FIG. 2 showing the state before welding and FIG. 3 showing the state during welding, respectively.

1.2 is a pair of upper and lower electrodes similar to those explained in FIG.
(not shown), and the electrode 2 is attached to a moving platen (not shown).
A pair of plate-like welded materials (steel plates) w and w' which are butted against each other are respectively clamped by the electrodes 1.2. That is, the electrode 1 on the fixed side clamps one of the plate-shaped materials to be welded W, and the electrode 2 on the movable side clamps the other plate-shaped material to be welded W'. Then, while applying a voltage between both electrodes 1 and 2, the movable platen is advanced to advance the workpiece W' clamped to the electrode 2.

In this case, substances 3 that generate gas during welding are placed on the upper and lower surfaces of the welded materials w and w' in the vicinity of the butt portions, respectively.
is attached in advance. The substance 3 that generates gas during welding may be any substance that generates a gas other than oxygen due to the heat during welding, and specifically includes the following.

(a) Carbon polymers, organic compounds, or organosilicon compounds (b) Zinc or zinc powder-containing substances e→ Alloys or intermetallic compounds containing calcium or magnesium, or substances containing them, and the methods of adhering them include the following: There is a way.

(1) A method in which each substance is made into a paste and applied with a brush, etc. (11) A method in which a viscous liquid mixed with an alloy containing zinc powder, magnesil, etc. is dropped onto the target material (111) Zinc powder, A method of pressing a thermoplastic substance mixed with magnesium-containing alloy powder, etc. onto the surface to be attached (M) A method of thermal spraying by spraying finely molten zinc, magnesium-containing alloy, etc. onto the surface to be attached■ Method of plating with zinc etc. The width from the end face of the part to which the substance 3 is attached (l7, 12 in the figure) is not particularly limited, but the attached substance 3 is not particularly limited at least until the moment the upset process begins. It is desirable that there be one.

Now, the material to be welded W to which the substance 3 is attached as described above.

When the butt end faces of W′ approach each other and touch slightly,
A short circuit current flows through the contact portion, and the contact portion is heated due to Joule heat generated in that portion, and a portion of the heated portion melts and scatters. After it scatters, an arc is generated at that location as described above, and due to the arc generation, molten metal becomes a flash and scatters from the end faces of the welded materials w, w', and the welded materials w, w' Electrical contact between them is severed. During this time, the movable platen continues to move forward, and after a short period of time, the end surfaces come into contact with each other again, and the same process as described above is repeated.

After this flashing process, the platens on both sides are rapidly moved to stop the flash from occurring, and the butt parts are pressurized for a predetermined period of time with the entire end surfaces of the workpieces w and w' in close contact with each other for upsetting. do. Welding ends with the upset process.

Now, in the flashing process mentioned above, the adhered substances 3
As shown in Fig. 3, the manganese easily turns into steam 4, and the area around the heated part is shielded from the atmosphere due to its steam pressure, resulting in the manganese in the welded materials w and w'.

Since the oxidation of alloy components such as silicon and chromium is prevented, their oxides will not remain in the weld.

Therefore, the resulting welded part is excellent in that it does not crack or the like even when subjected to tensile stress or bending stress.

In addition, in this example, the substance 3 that generates gas during welding is attached to the upper and lower surfaces of the welded materials w and w' near the abutting portions, respectively, but the generated gas generally rises. Therefore, even if the substance 3 is attached only to the lower surface, the effect of the method of the present invention can be fully expected.

Next, specific examples of the method of the present invention will be described. A pair of steel plates having the chemical components shown in Table 1 and having a thickness of 3 mm were used as test materials, and the test materials were butted together and subjected to flash butt welding under the welding conditions shown in Table 2. In this case, each substance shown in Table 3 was attached only to the lower surface of the welded materials near the butt.

Table 1 Table 2 Table 3 The resulting welds are determined by bending the welded specimen with the weld in the center and deforming it into a flat and tight state. Divided by the total length of the part: 1
Evaluation was made using the value multiplied by 00, that is, the defect occurrence rate. The results are shown in Table 3, which shows that No. 1, to which the method of the present invention was not applied, had a defect incidence rate of 100, whereas No. 2 to No. 1, to which the method of the present invention was applied, had a defect incidence rate of 100. No
, 8 was found to have a defect incidence rate of 2 to 9%,
The excellent effects of the method of the present invention could be confirmed.

As detailed above, when performing flash butt welding by butting plate-shaped materials to be welded using the method of the present invention, an alloy containing an organic compound, zinc, or magnesium is added to at least the lower surface near the butt portion of the materials to be welded. Since welding is performed after attaching a substance that generates a gas other than oxygen during welding, the vapor pressure of the gas generated shields the area around the heated area from the atmosphere, preventing oxidation of the alloy components in the welded material. It is possible to prevent these oxides from remaining in the welded area. Therefore, it can be said that the present invention provides a simple method for avoiding the oxides remaining in the welded joint and maintaining high quality of the welded joint.

[Brief explanation of the drawing]

Figure 1 (a) (b) (c) (d) (e) is an explanatory diagram of the principle of the flash butt welding method, Figures 2 and 3
The figure is a schematic diagram showing the implementation state of the method of the present invention. w, w'... Material to be welded 1, 2... Electrode 3...
Adhesive substance 4...Steam patent applicant Noboru Kono, Patent attorney representing Sumitomo Metal Industries Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. When flash butt welding is performed by butting plate-shaped materials to be welded together, (a) a carbon polymer, an organic compound, or an organic A flash butt welding method characterized by welding after depositing either a silicon compound (b) a substance containing zinc or zinc powder (c) an alloy containing calcium or magnesium, an intermetallic compound, or a substance containing it.