JP4372265B2 - Welding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling the start of cutting in gas cutting when the surface to be cut is not flat.
[0002]
[Prior art]
In the final process of manufacturing slabs (hereinafter referred to as steel slabs), when the upper and lower surfaces of steel slabs are cut by a gas cutting machine to remove surface flaws, as shown in FIGS. Hangs down from the upper surface to the end surface, or extends from the lower surface to the end surface, and adheres as sagging 3 and 4 after cooling.
[0003]
Such a sag (hereinafter referred to as “slab sag”) is obtained by re-solidifying the melted steel slab. If rolled while attached, there is a risk of steel plate flaws that must be removed before rolling. Rather, manual cutting using a hand scarf nozzle, grinder grinding and a mechanical gas cutting machine are generally used. In the case of cutting with a mechanical gas cutting machine, preheating of the end face is required before starting the cutting, and the preheating time is controlled by a timer. Conventionally, however, there has been no method for removing this welding sag mechanically and automatically.
[0004]
[Problems to be solved by the invention]
When the end face to which this welding sag adheres is preheated, it is not heated uniformly due to large irregularities and undulations existing on the end face, resulting in insufficient heating, resulting in failure to obtain good cutting results. It was. Such a tendency was strongly recognized especially in the cold cutting of cold material.
[0005]
The present invention has been made in view of the above points, and its purpose is to eliminate the uneven heating state at the start of the welding in the preheating before the start of the welding and prevent the occurrence of uncut parts. The purpose of this is to provide a good method of cutting without leaving any residue by monitoring the state of the generated heat that is the main heat source for continuing the cutting with a temperature sensor or the like, and controlling the cutting speed and the amount of fuel gas .
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the welding method according to the present invention monitors the preheating state of the welding start location by using a temperature detection device such as a temperature sensor or an ITV camera before starting the welding. After confirming that sufficient heating has been achieved without generating a part to be cut, start cutting and then monitor the surface to be cut during the cutting and control the cutting speed, fuel gas amount, etc. It is characterized by doing.
[0007]
That is, in the method of cutting according to the present invention, the step of preheating the end face of the steel piece to be cut, the end face is divided into a plurality in the thickness direction, and the heating state of the preheated end face is monitored for each of the sections. The process, the process of starting the cutting when the end face of the steel slab is in a heated state necessary for the cutting, and the temperature of the plurality of cutting surfaces during the cutting, And a step of controlling the amount of fuel gas.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
FIG. 1 is a steel slab manufactured by continuous casting, and shows a state after the upper and lower surfaces have been cut. 1 is a steel piece. No. 2 is an end face, and the generated slack generated when the upper and lower surfaces of the steel slab are cut off is cooled and attached as a cutting sag 3 and 4. FIG. 2 shows a side view.
[0011]
FIG. 3 is a plan view showing the welding sag removing operation. The welding crater 5 of the gas cutting machine moves in the direction of arrow A with respect to the steel piece 1 to remove the welding sag 3 and 4. It is also possible to fix the cutting crater 5 and move the steel piece 1. FIG. 4 shows a front view.
[0012]
The implementation of the cutting method according to the present invention will be described with reference to FIGS. The cutting crater 5 of the gas cutting machine forms a slit-shaped oxygen spout 6 for cutting oxygen by superimposing an upper unit 51 and a lower unit 52 vertically. First, the fuel gas is ejected from the fuel gas ejection ports (not shown) of the upper unit 51 and the lower unit 52, and the low pressure oxygen is ejected from the oxygen ejection port 6 to form the preheating flow 7, and the welding starts. The point P is heated. Then, the heating state is monitored by the temperature sensor 8 or the ITV camera 8 ′ arranged to face the end surface 2.
[0013]
FIG. 6 shows the monitoring method. Since the end surface has uneven welding and large irregularities, it is desirable to monitor by monitoring the spot according to the state. FIG. 7 shows a situation in which the temperature of the surface to be cut decreases due to the lack of the cutting edge during the cutting (due to the lowering of the cutting edge due to gravity, etc.), and the uncut portion 9 appears. is there. In the description of this embodiment, the point P is divided into P1 to P4 in the thickness direction of the steel slab. After confirming that each section has a temperature suitable for the start of welding with an image processing system, etc., provided separately, which is not clearly shown in the figure, the pressure of the welding oxygen is switched to a high pressure, and the welding is started. Continue to perform cutting while generating
[0014]
After starting the cutting, the temperature of the surface to be cut is monitored by the temperature sensor 8 or the like interlocked with the cutting crater 5, and if the temperature of the surface to be cut decreases and the uncut portion 9 appears, the cutting speed immediately The amount of fuel gas and the like are controlled by a control device (not shown) coupled to the image processing system so as to obtain a good surface to be cut.
[0015]
In addition, although the cutting is in the direction of arrow A from the point P at which preheating starts, it is also possible to return the welding crater to point B at the slab corner and advance in the direction A after preheating at point P. In addition, this invention exhibits an effect about the case where a to-be-cut surface is not flat, and it is not limited to the case of the welding which adhered to the steel piece end surface which the application object demonstrated above.
[0016]
【The invention's effect】
As described above, according to the welding method of the present invention, the heating state at the location where the welding starts is directly monitored with a temperature sensor, an ITV camera, etc., and the temperature distribution is such that no uncut portion is generated. Since the temperature of the to-be-cut surface to be cut is continuously monitored after confirmation, there is no need to perform the cutting operation again, and a uniform cut surface can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the state of adhesion of a welding sag on the end surface of a steel slab. FIG. 2 is a side view of the same. FIG. 3 is a schematic diagram showing the state of removal of a welding sag. 5 is a diagram for explaining the implementation of the present invention. FIG. 6 is a diagram showing an example of temperature distribution measurement at the starting point of welding. FIG. Diagram showing the situation [Explanation of symbols]
1 ... billet,
2 ... end face,
3 ... Scraping from above,
4 ... Scraping from below,
5 ...
51 Upper part of the cutting crater 52 Lower part of the cutting crater 6 ... The cutting oxygen outlet,
7 ... Preheating flame,
8 ... Temperature sensor,
8 '... ITV camera,
9 ... Uncut part

Claims (1)

A process of preheating the end face of the steel piece to be welded ;
Dividing the end face into a plurality of thickness directions, and monitoring the heating status of the preheated end face for each of the sections ;
In each section, the process of starting the cutting when the end face of the steel slab is in a heating state necessary for the cutting ,
The temperature of the plurality of scarfing surface is monitored during scarfing, and controlling the scarfing speed and amount of fuel gas
A method of melting an end face of a steel slab characterized by comprising :

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