JPS61209768A - Repairing method using scarfing - Google Patents

Abstract

PURPOSE:To adjust the density of oxygen gas and to hold properly the sectional shape of a material to be scarfed by spouting a nitrogen gas in addition to oxygen gas or oxygen gas from the torch for side fin removal provided at both sides of gas welding torch. CONSTITUTION:In case of the surface temp. of a material A to be scarfed being low, scarfing is born in the oxygen gas spouted from a main nozzle 12 and the side fin (a) to be generated therein is removed by the oxygen gas jetted from the torch 13 for side fin removal. In this case, it is unnecessary to consider the generation of the secondary scarfing by the torch 13 due to the temp. of the material A being low and the high and low in the surface temp. can be coped with the pressure adjustment of the oxygen gas of the torch 13. In case of the surface temp. of the material A being high, then the density of the oxygen gas is reduced by jetting the inert gas of nitrogen gas, etc. together in addition to the oxygen gas and the progress of the scarfing is controlled, also the genera tion of side fin (a) is prevented and the generation of the secondary scarfing (b) is prevented as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for treating materials to be machined, such as steel plates and slabs.

[Prior art and its problems]

In general, when cutting with a cutting tip, side fins are formed on both sides of the cut part, and a cutting method that simultaneously removes these side fins was developed in the Japanese Patent Publication No. 56-2.
The disclosure is proposed in No. 6515.

This is 1. As shown in W4rIIJ(a)&:1), a distribution block 2 is installed below the main body block 1, and an oxygen chamber 3 and a nonflammable gas chamber 4 are installed in the distribution block 2.
Both chambers 3 are provided with passages 3m and 4m.
, 4 are communicated with a cutting oxygen outlet 5, and nonflammable gas is ejected on both sides of the cutting oxygen to prevent the formation of side fins. This is a method in which the amount of gas is varied between cold and hot materials.

In other words, in the above method, air or nonflammable gas is blown out from both sides of the cutting oxygen to prevent side fins from forming, so that the oxygen concentration has a gradient that decreases near the edge of the cutting area. However, there are the following problems.

(2) Since this is a method of lowering the oxygen concentration near the edge of the fusing process, the fusing area becomes narrower as shown in FIG.

■The material to be welded is divided into hot and cold materials with different oxygen concentrations, but the surface temperatures of both hot and cold materials vary widely, and there are no rules. The occurrence of side fins cannot be prevented by oxygen concentration.

Therefore, in order to prevent the W from decreasing during cutting, it is conceivable to use a gas cutting torch 11 attached with a side fin removal torch 13 as shown in Fig. 1G)@.
When only oxygen gas is ejected from the side fin removal torch 13 to the material to be machined, which has a high surface temperature,
If the pressure of the oxygen gas from the side fin removal torch 13 is lowered too much, the side fins a will remain (Fig. 5 (b)); if the pressure is increased slightly, the side fin removal torch 1
Even with N5, partial melt cutting so-called secondary melt cutting 1 occurs, and N5
As shown in Figure (C), the cross-sectional shape of the melt cut becomes poor.

In other words, the width of the optimum value of the oxygen gas pressure of the side fin removal torch 13 is very narrow, and this adjustment is difficult in practice.

[Objective and technical means]

Under the above-mentioned circumstances, the present invention has been developed to provide a melt cutting method that can improve the cross-sectional shape of the melt cut without constricting the cutting area, and can also adjust the injection jet appropriately for various surface temperatures of the material to be cut. The following technical measures will be adopted.

That is, the present invention is a method for cleaning the surface of a material to be cut, such as a steel plate or a piece of steel, by using a gas cutting torch attached with a torch for removing side fins, and the surface temperature of the material to be cut is low. In some cases, only oxygen gas is ejected from the side fin removal torch at a pressure corresponding to the surface temperature, and if the surface temperature of the workpiece is high, an inert gas such as nitrogen or argon is added. Its feature is that oxygen gas is ejected at a concentration corresponding to the surface temperature.

Here, "when the surface temperature is low" means "when the surface temperature is low enough to cause secondary cutting", and the r surface 'aL
``When the temperature is high'' means ``the surface temperature is such that secondary cutting is likely to occur, and this boundary temperature differs depending on the steel type of the material to be cut.

[Effect]

The present invention is carried out using a gas melting torch 11 as shown in FIG. 1H) (front view) and FIG. 1-) (plan view). In the same figure, 12 is the main nozzle that spouts oxygen gas, which is responsible for the main purpose of bright cutting, and 13 is the main nozzle that ejects oxygen gas to remove the side fin a, or the generation of the side fin 1 while preventing the occurrence of secondary cutting. In order to prevent this, this is a torch for removing alkaline fins that ejects with an oxygen bath containing inert gas.
indicates the nozzle angle of the main nozzle 12, and θ indicates the nozzle angle of the side fin removal torch 13.

Using the gas cutting torch 11 as described above, first, when the surface temperature of the material to be cut is low, the oxygen gas ejected from the main nozzle 12 is responsible for cutting, and the side fins a generated there are The side fins are removed using oxygen gas injected from the side fin removal torch 13.

Therefore, the width W during melt cutting does not become fixed or narrowed depending on the injection from the main nozzle 12. In this case, since the temperature of the material to be welded is low, there is no need to consider the occurrence of secondary machining caused by the so-called side fin removal torch 13; Adjusting the pressure of the oxygen gas ejected from the fin removal torch 13 can be sufficient.

Next, if the surface temperature of the material to be cut is high and there is a risk of secondary cutting, an inert gas such as nitrogen gas is injected in addition to oxygen gas. The concentration of oxygen gas is reduced to suppress the sharp progress of melt cutting, thereby preventing the generation of side fins a and preventing the occurrence of secondary melt cutting.

[Experiment example]

Various experiments were conducted using a gas cutting torch 11 with side fin removal torches 13 attached to each side of the main nozzle 12, as shown in FIGS. 1(a) and 1(b).
In order to obtain the good cross-sectional shape shown in FIG. 3, the pressure value and concentration of the oxygen gas ejected from the side fin removal torch 13 were determined. The results are shown in FIG.

During melt cutting: W = 100-120 ■ Material to be cut: Carbon steel continuous casting slab Main nozzle 12 tip opening: Width 5 ■ 9 Area 150 Nozzle angle of main nozzle 12 201-30 degrees Opening of side fin removal torch 13: Width 5 ■ Area 50 - Nozzle angle of side fin removal torch 13 = 01 = 30
゜Inert gas dinitrogen gas used [Effect] As explained above, the present invention has the following advantages:
This was done by paying attention to the sharp change in the surface temperature of the material to be cut, and in the range where it is dull and difficult to cause secondary cutting, oxygen gas is applied from the side fin torch. The oxygen gas pressure from the side fins is responsible for the proper removal of the side fins, and on the other hand, in the Vh range that is sharp and tends to cause secondary cutting, the oxygen gas In addition, nitrogen gas is injected to suppress the sharpness of melt cutting, and oxygen gas concentration can be adjusted to improve melt cutting! It is designed to maintain the proper shape of the rr surface, and has the advantage of being able to cut materials from low to high temperatures without generating side fins or reducing the cutting time. play.

[Brief explanation of drawings]

Fig. 1 (to) is a front view of the melting torch used in the present invention, Fig. 1 (b) is a plan view thereof, Fig. 2 is a graph showing an example of experimental results of the present invention, and Fig. 3 is a front view of the melting torch used in the present invention. Cross-sectional shape of melt cutting, Fig. 4 B) is a perspective view of a conventional melt cutting torch, Fig. 4-) is an enlarged sectional view of the roller in Fig. 4 G), Fig. 5 G) (B)
(c) is an explanatory diagram of problems with the conventional melt cutting method. Person is the material to be machined, 13 is a torch for side fin removal, a is side fin, and b is secondary melt cutting. $2 Figure Figure 4 (4) Figure 4 (c2)

Claims (1)

[Claims] A method of cleaning the surface of materials to be machined such as steel plates and slabs using a gas cutting torch equipped with a torch for removing side fins.If the surface temperature of the material to be machined is low, the side fins may be removed. Only oxygen gas is ejected from a torch at a pressure corresponding to the surface temperature, and when the surface temperature of the material to be welded is high, oxygen gas to which an inert gas has been added is ejected at a concentration corresponding to the surface temperature. A fusing maintenance method characterized by ejecting water.