JPH07303963A - Welding method for steel with rectangular cross section - Google Patents

Abstract

(57) [Summary] [Purpose] A fusing unit that uses molten slag to spread and infiltrate,
Particularly, the present invention provides a fusing method for preventing clogging of a fusing crater of a lower surface fusing unit. [Structure] Along the upper edge of the longitudinal end face of a steel material having a rectangular cross section, the tip of the oxygen ejection hole is located above the fuel gas ejection hole tip position and is retracted to position the upper surface fusing unit, and at the same time, Along the lower edge of the longitudinal end face of the steel material, after arranging the lower surface fusing unit in which the oxygen ejection hole tip is aligned below the fuel gas ejection hole tip position, oxygen gas and fuel gas are placed on the surface of the steel material. It is characterized in that it is jetted and the upper and lower surfaces of the steel material are ablated from one end to the other end in the longitudinal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to at least the upper and lower surfaces of a rectangular cross-section steel material such as a slab, plume or billet,
The present invention relates to a fusing method of fusing in the longitudinal direction.

[0002]

2. Description of the Related Art Steel materials having a rectangular cross section such as slabs, plumes and billets are raw materials for various rolled products. However, defects existing on the upper and lower surfaces and both side surfaces of the rolled products are defects of the product after rolling, and therefore, before rolling. The surface ablation method using combustion gas is known and is commonly used.

There are a partial fusing method of fusing a part of a steel material and a so-called whole fusing method of fusing the entire upper and lower surfaces and both side surfaces of the steel material. The whole surface ablation method is shown in Fig. 2 (a).
As shown in Fig. 5, the upper and lower surfaces 5a and 5c of the steel material 3 and both side surfaces 5b,
5d along the width direction of each of the fusing units 20a to 20d
Are arranged, and by these, the fusing and cutting of the upper and lower surfaces and both side surfaces of the steel material are simultaneously started.

This full-face welding is roughly divided into a face start method and an edge start method, the former of which is shown in FIG.
As shown in (b), the top and bottom and both side surfaces 5a to 5d of the steel material 3
A predetermined width position D1 close to the ridge 6a of the end face in the longitudinal direction is set as the preheating position, and a welding cutting start position after preheating is set. This is for the fusing unit 20 when starting fusing after preheating.
The oxygen jet flow 10a from the ablation crater 1a of a collides with the ablation start position D1 to generate shunts 11a and 12a, and the shunt 12a causes a part of the slag to move far rearward along the longitudinal end 4a. Blown away, the fusing unit 20 on the lower surface side
This is because it is possible to prevent slag from entering and adhering to the fusing tip 1c and the preheating tip 7c of c.

In the latter case, as shown in FIG. 3A, a flame 9a from the preheating crater 7a causes a ridge 6a which intersects the longitudinal end surface of the steel material with the upper and lower and both side surfaces, that is, the surface to be ablated (only 5a is shown). To-be-welded surface portion D2 20 to 70 mm away from
3B, the preheating crater 7a is relatively moved to the edge 6a side to widen the melting width, and then the oxygen jet 10a is jetted from the fusing crater 1a as shown in FIG. 3 (b). It is intended to start the fusing from 6a.

[0006]

However, in the former surface starting method of the prior art, as shown in FIG. 2 (c), the longitudinal end portions 4a of the upper and lower and both side surfaces 5a to 5d of the steel material 3 are unwelded zones. 21 remains and causes surface defects in the rolled product, and a deep digging portion called gouging occurs at the position D1 where the welding is started, as shown in FIG. The yield was remarkably reduced due to surface defects.

Further, in the latter edge start method of the prior art, since the ridges 6a at one longitudinal end of the upper and lower sides and both side surfaces of the rectangular cross-section steel material 3 are set as the subsequent preheating position and the welding start position after preheating, As shown in FIG. 3C, the oxygen jet flow 10a from the ablation crater 1a of the ablation unit 20a on the upper surface is
When colliding with the welding start position, the shunts 11a and 12a are vertically divided.
Then, part of the molten slag is blown off along the longitudinal tip surface 4a of the steel material by the shunt 12a, and enters and adheres to the shaving crater 1c and the shaving fuel gas hole G1 of the shaving unit on the lower surface side of FIG. Makes it impossible to ablate.

The present invention is intended to solve the above-mentioned problems, and when the entire surface of the steel material is ablated from one end to the other end in the longitudinal direction, the abrading unit, in particular, the underside ablation by the intrusion of molten slag. An object of the present invention is to provide a fusing method that prevents clogging of the fusing crater of a unit.

[0009]

In order to achieve the above object, the present invention provides an upper ridge L1 of a longitudinal end surface of a steel material having a rectangular cross section.
The oxygen gas ejection hole tip 2a along the fuel gas ejection hole tip G
Above the 2 position and retracted to the upper surface of the fusing unit 20
a is located, and the lower surface fusing unit 20c in which the oxygen ejection hole tip 2c is aligned below the fuel gas ejection hole tip G1 position is located along the lower edge L2 of the longitudinal end surface of the steel material having the rectangular cross section. Then, an oxygen gas and a fuel gas are ejected onto the surface of the steel material, and the upper and lower surfaces of the steel material are abraded from one end to the other end in the longitudinal direction.

[0010]

FUNCTION AND EXAMPLE The present invention will be described below with reference to an example shown in FIG. In the present invention, when the upper and lower surfaces of the steel material are ablated from one end to the other in the longitudinal direction, a part of the melted Noro D due to the ablation fuel gas and the oxygen gas from the upper surface unit 20a is in the longitudinal direction of the steel material. The nozzle block 23 is blown toward the tip surface, and the other part of the nozzle block 23 does not reach the tip G1 of the fuel gas ejection hole of the lower welding unit 20c and the tip 2c of the oxygen ejection hole but forms the oxygen ejection hole.
Deposit on top. Further, a part of the molten slag D on the lower surface of the steel material advances toward the distal end in the longitudinal direction of the steel material, and another part reaches the lower fusing unit 20c side, but is blown away from the above-mentioned upper surface portion. Similarly to the nozzle block 2
3 or the tip 1 of the oxygen jet ejection hole
It is blown off by the oxygen jet from c and the tip 2 of the ejection hole
It does not directly enter or adhere to c or the tip G1 of the fuel gas ejection hole.

In this way, the method of fusing according to the present invention includes the tip G1 of the fuel gas ejection hole of the lower fusing unit 20c,
It is possible to reliably prevent the molten slag from entering and adhering to the tip 2c of the oxygen ejection hole, and to perform the smooth cutting of the rectangular cross-section steel material on the upper and lower sides and both side surfaces in the longitudinal direction without leaving any unmelted portion. It is what

[0012]

[Table 1]

The steel slabs shown in Table 1 were tested by the conventional shaving method shown in FIG. 2 and the smelting method of the present invention shown in FIG. 1 under the welding conditions shown in the same table. Although clogging occurred after the fusing of the eight sheets, the clogging did not occur even after fusing the eight sheets in the method of the present invention.

[0014]

According to the present invention, by the above construction, it is possible to surely prevent intrusion and adhesion of the molten slag in the fuel injection hole of at least the upper and lower surfaces of the rectangular cross section steel material, or the lower surface smelting unit in the entire surface smelting, and eliminate the blockage. The present invention enables the smooth cutting of the steel material and the free cutting without the unmelted portion in the longitudinal direction of the steel material.

[Brief description of drawings]

FIG. 1 is a simplified diagram of a state of fusing according to the method of the present invention.

FIG. 2 is a simple configuration diagram (a) of a steel material melting and ablation device,
The figure which shows the shape (b) of the conventional example at the time of the surface start, and the shape (c) after the steel material is ablated.

FIG. 3 is a simplified diagram showing an edge start order (a) to (c) in a conventional fusing method.

[Explanation of symbols]

 1a Upper unit welding oxygen nozzle 1c Lower unit welding oxygen nozzle 2a Upper unit welding oxygen nozzle tip 2c Lower unit welding oxygen nozzle tip 3 Cross section rectangular steel material 4a Steel material end portion 5a Steel material upper surface 5b Steel material right side surface 5c Steel material lower surface 5d Steel material Left side 6a Steel material upper ridge 7a Upper preheating unit 7c Lower preheating unit 9a Preheating oxygen and gas jet flow 10a Smelting oxygen jet flow 11a Molten slag advancing to the longitudinal rear end of steel material 12a Molten slag advancing to the longitudinal end of steel material 20a Upper unit 20c Lower unit 21 Unmelted part 22 Deep-deep part 23 Shoe block D Melting Noro L1 Steel material upper edge L2 Steel material lower edge G1 Lower unit fuel gas nozzle tip G2 Lower unit fuel gas nozzle tip

Claims (1)

[Claims] Along the upper edge of the longitudinal end surface of the steel material having a rectangular cross section, the tip of the oxygen ejection hole is moved back and above the tip of the fuel gas ejection hole to position the upper surface fusing unit and the longitudinal direction of the steel material having the rectangular cross section. Along the lower edge of the end face, after arranging the lower surface fusing unit where the oxygen ejection hole tip is aligned below the fuel gas ejection hole tip position, eject oxygen gas and fuel gas onto the surface of the steel material, A method of fusing a steel material having a rectangular cross section, characterized in that the upper and lower surfaces of the steel material are subjected to fusing from one end to the other end in the longitudinal direction.