JPH0675782B2 - How to repair tongue punches - Google Patents

Description

TECHNICAL FIELD The present invention relates to a padding repair method for a punch for tongs, and more particularly to a carbon steel or a low alloy steel detachably attached to the inside of a tongue for heating steel ingots. A method of repairing a tongue punch, which is a base material, by overlay welding having excellent crack resistance and is widely used in the field of rolling or forging of steel.

[Conventional technology]

Conventionally, the tip of the punch for tongs, which sandwiches the heated steel ingot, is worn a lot because it is repeatedly used when the high temperature steel ingot is moved, and after the wear, it is used by overlay welding with a heat and wear resistant welding material.

As shown in Fig. 2, the conventional repair of the punch tip by build-up welding is to smooth the tip 2A of the punch 2 and then
First, underlay welding is performed with a welding material that is equivalent to or slightly higher in strength than the base metal of the tongs 2, and then hardened heat resistant and wear resistant material is overlaid on top of it. There was a defect that cracks were generated at the boundary part of the, the reliability of the punch decreased, and the life was short.

Japanese Patent Laid-Open Publication No. 49-22368 discloses a "crane tong for cold slag" as a technique for hardfacing the tip of a punch for tongs. In the method of overlay welding directly to the base material with an arc welding rod, there is no great difference from the conventional method, and the defect that cracks occur in the base material and the overlay welding part is still unsolved under the present circumstances. is there.

[Problems to be solved by the invention]

An object of the present invention is to provide a repairing method which solves the problems of the above-mentioned conventional repairing method by build-up welding of a punch for tongs, has high reliability without cracking, and can extend the life.

[Means for solving problems]

 The gist of the present invention is as follows.

That is, in a method for overlaying a tongue punch having a base material of carbon steel or low alloy steel that is detachably attached to the inside of the heated steel ingot tongue, the base material is formed on a flat surface portion formed at the tip of the tongue punch. And a step of under-welding with a weld metal having a higher strength, a step of overlay welding a core material made of a high-hardness weld metal on the under-welding metal formed, and the formed core material And a step of coating and welding the underlaying weld metal on the weld metal, the overburden repairing method for the punch for tongs.

The details of the present invention will be described by way of examples with reference to the accompanying drawings. 1 (A), (B), (C), and (D) are schematic cross-sectional views showing the procedure of build-up welding according to the present invention. First, as shown in FIG. 1 (A), the pointed portion 2A of the punch 2 to be repaired is formed into a flat shape by a grinder or the like, and a flat welding metal having a strength equal to or slightly higher than that of the base metal is formed on the flat portion. And the meat is heaped to form the lower heap portion 4. Next, the core material 6 is welded to the formed underfill portion 4 by using a weld metal having a high hardness as shown in FIG. 2 (B). The core material 6 welded by overlay welding is shaped into a chevron shape by a grinder or the like, as shown in FIG. 1 (C).

Next, a welded metal having the same or similar composition as that of the base material is used so as to wrap the shaped core material 6 to form a coating portion 8 that covers the core material 6 like a thin skin bun shape. Cover 8
It is preferable that the build-up thickness of 3 to 5 mm. After the buildup is completed, the surface is finished by a grinder to obtain the shape shown in FIG.

Table 1 shows an example of the chemical composition and mechanical properties of the base material of the punch 2, the base member 4, and the core material 6 used in the present invention.

[Operation and Effect of the Invention] As described above, the repair method according to the present invention has the tip portion of the punch 2.
In overlay welding 2A, first, the tip portion 2A is grind-formed into a flat surface, and then the lower overlay portion 4 is formed by using welding having the same strength as or slightly higher strength than the base metal, and then the core is placed on this. Since the material 6 is build-up welded and the covering portion 8 is built-up welded on the material 6 by the same or similar material as the lower fill part 4, the punch 2 and the lower fill part 4 are made of the same or similar material. Since it is present, it is completely welded, and the core material 6 is firmly protected by the overlay coating of the uppermost coating portion 8, and
The peripheral portion of the core material 6 other than the core material 6 is made of the same or similar material as the lower heave portion 4, and the sharpest end is thin at 3 to 5 mm, but becomes thicker as it goes below the core material 6. 8
Due to the function and effect that the core portion 6 surrounds the core material 6 and becomes firmly integrated, the expansion and contraction also occur due to heating and cooling during welding between the metals at the boundary between the respective members. It is considered that there is almost no residual stress for keeping the rate together, and as a result, not only the performance of the high hardness core material 6 can be fully utilized but also the effect of extending the life without cracking can be achieved. It was

In the punch which has been repaired by the repair method according to the present invention, the total weight of hoisting heated steel ingots before use becomes drastically increased from 280t to 1252t per piece according to the present invention. The effect of is confirmed.

[Brief description of drawings]

FIGS. 1 (A), (B), (C), and (D) show the order of steps of the repair method according to the present invention, and (A) is the formation of underlay welding,
(B) At the time of forming the core material, (C) at the time of completing the grinder finishing of the formed core material, and (D) at the time of forming the covering portion on the core material,
FIG. 2 is a schematic cross-sectional view, and FIG. 2 is a partial cross-sectional view showing a tongue punch that has been repaired by the present invention. 2 ... Punch for tongs, 2A ... Tip part 4 ... Underlay part, 6 ... Core material 8 ... Cover part

Claims (1)

[Claims] 1. A method for repairing a build-up of a tongue punch, which is detachably attached to the inside of a heated steel ingot tongue and which uses carbon steel or low alloy steel as a base material, wherein a flat surface portion formed at the tip of the tongue punch is used. A step of underlay welding with a weld metal having a strength equal to or higher than that of the base material; a step of overlay welding a core material made of a high hardness weld metal on the underlay weld metal thus formed; And a step of covering and welding the underlaying weld metal onto the core material weld metal, the overlay welding repair method of the punch for tongs.