JPH04238680A - Butt welding method for strips - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to butt welding for the continuous production of strips of high carbon steel, electrical steel sheets, stainless steel sheets, etc.

0002

2. Description of the Related Art When performing laser butt welding for coiling a rolled strip, its leading and trailing ends are precisely cut at right angles to its running direction (width direction) using a guillotine shear. This cut surface does not have linearity in the width direction of the sheet, and gap fluctuations cannot be avoided at the abutting surfaces.

[0003] In order to form a good weld by laser welding a strip having this cut surface by supplying a welding wire, the amount of heat supplied to the weld and the amount of bead formed after welding must be appropriate. be. If the amount of heat supplied is too large, embrittlement will occur due to the growth of crystal grains in the heat-affected zone due to welding, if it is too little, the bond will be insufficient due to insufficient penetration, and if the amount of beads is too large, the bond will fail. Post-processing for smoothing the parts requires time and effort.

[0004] As an automated method for optimizing the amount of heat supplied and the amount of bead formed during butt welding of strips, Japanese Patent Application Laid-Open No. 62-40989 discloses that a metal paste such as metal powder or metal foil is applied to both ends of the butt weld. It has been disclosed that the welding process is performed by placing a metal on the metal and then irradiating it with an energy beam such as an electron beam or a TIG arc.

However, when cutting for welding,
In order to maintain the straightness of the cut surface, the cutting blade of the guillotine shear is set to touch the strip surface at an angle, and there is also a gap between the cutting blade and the strip steel plate during cutting, so that As shown, the cut surface of the strip S in the width direction is not straight.
(error of about 5 mm) variation of about 40 to 50%.

However, in conventional automatic welding programs, the feed speed of the filler wire is adjusted to a constant gap, which has the disadvantage that the height of the bead rises depending on the variation in the cutting gap, which tends to cause welding defects. .

As a countermeasure to this problem, in order to reduce the gap error in order to obtain straightness during cutting, it is possible to increase the rigidity of the cutting equipment and cut the strip by applying the entire surface of the cutting blade horizontally to the surface of the strip. Although it is possible, the cost will increase considerably due to the increase in equipment.

[0008]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to establish automated means for butt welding strips to obtain a good welding condition regardless of variations in the cutting gap.

[0009]

[Means for Solving the Problems] In the method for butt welding strip steel plates of the present invention, in order to obtain appropriate welding conditions for various gap amounts, a calculation device calculates the correlation between wire supply speed and welding speed for each plate thickness in advance. detecting the gap amount of the cut surface during welding, inputting the detected gap amount to the calculation device, and obtaining an appropriate welding condition for the detected gap amount from the correlation stored in advance in the calculation device. It is characterized by obtaining wire feeding speed and welding speed for.

0010

[Operation] The present invention continues welding by determining the wire supply speed and welding speed based on the gap detected during welding.The filler wire supply speed is linked to the welding speed to eliminate excess or deficiency of heat input. By changing the amount of filler wire supplied in accordance with gap fluctuations that occur during cutting and butting operations, it is possible to control the height of the excess of the formed bead.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a control system diagram for implementing the present invention. FIG. 2 shows a relationship diagram between wire supply speed and welding speed for obtaining appropriate welding conditions for various gap amounts that are stored in advance in the calculation device. In Figure 1,
1 shows the welding gap formed between the respective cut end surfaces of the first strip S1 and the second strip S2 as viewed from a horizontal plane (in the width direction of the steel plate). This welding gap 1 is vertically cut by a shearing device such as a guillotine shear in the pre-welding stage, but the cut surface in the width direction of the plate is not a straight line and exhibits the recess 1-1 shown in Fig. 3. It doesn't look constant. Reference numeral 2 denotes a welding device, which includes a wire supply pinch roll 23 for supplying the filler wire 22 from the filler wire drum 21 to the welding gap 1 and a roll drive motor 24 for driving the pinch roll 23. 25 again
indicates a laser processing head, and fluctuations in welding speed due to this laser processing head 25 are caused by processing head movement motor 2.
6.

Reference numeral 3 indicates a control system for controlling the supply speed and welding speed of the filler wire 22. This control system 3 includes a gap sensor 31, such as a CCD camera, which moves across the welding gap 1 in the width direction to detect the gap, and a filler wire supply to obtain an appropriate welding condition for various gap amounts depending on the plate thickness. The correlation between the speed and the welding speed is stored in advance, and the gap sensor 31
The arithmetic unit 32 outputs control signals for the wire supply speed and the welding speed based on the correlation based on the magnitude of the gap detection value inputted from the arithmetic unit 32.

FIG. 2 shows an example of the correlation between the filler wire supply speed of a certain plate thickness and the welding speed, which is stored in the arithmetic unit 32. In the figure, the X-axis indicates the welding speed, which is set depending on the size of the gap, and the Y-axis indicates the supply speed of the filler wire to the welding gap 1. Curve A, B
and C shows the correlation line between the appropriate welding speed and filler wire supply speed corresponding to the size of the welding gap 1, and the curve A is 0.4±0.0 when the welding gap 1 is large.
5mm, and curve B is for example 0.3±0.05mm
, and curve C is small, for example 0.2±0.05mm
shows. Such a correlation line is determined in advance for each plate thickness and stored in the calculation device 32.

The control system shown in FIG. 1 operates in the following manner.

In FIG. 2, the steel plate S to be welded is known in advance.
A point b is specified on the correlation curve B according to the thicknesses of S1 and S2 and the size of the gap 1, a filler wire supply speed Yb corresponding to the welding speed Xb is set accordingly, and welding work is started. During welding work, the gap sensor 31 is moved across the welding gap 1 in the width direction to detect the gap amount, as shown in FIG. When the gap amount changes during the movement process, the correlation curve stored in the arithmetic unit 32 moves to curve A or C depending on the size of the gap 1, and the supply speed corresponding to that curve is changed to the filler wire roll. The welding speed is output to the drive motor 24 and the welding speed is output to the processing head movement motor 26.

The case where this gap detection value changes and the correlation curve moves will be described in detail. Now, when the gap detection value increases from 0.3 mm to 0.4 mm, there will be insufficient heat input at the previous welding speed Xb, so
The welding speed Xb is reduced, and since the excess buildup becomes excessive at the filler wire supply speed Yb, the welding speed Xb is reduced and the welding speed Xa and the filler wire supply speed Ya are controlled to avoid insufficient penetration and excessive excess buildup.

On the other hand, even when the gap becomes smaller,
The welding speed is changed to Xc and the filler wire supply speed is changed to Yc from the viewpoint of suitability of welding heat input and suitability of surplus of the welded part.

In this way, only the appropriate welding conditions based on the thickness of the treated steel plate and the welding gap are checked in advance, and the calculation device 32
By inputting and storing the data in the gap sensor 31, optimal welding can be achieved using only the data detected by the gap sensor 31.

[0019]

[Effects of the Invention] The following effects can be achieved by the present invention.

(1) Problems during cold rolling of welded parts can be reduced by changing the supply amount of filler wire and welding speed according to the gap and controlling the overfill height to reduce gap fluctuations that occur during butting operations. let

(2) Welding defects are prevented by interlocking filler wire supply speed and welding speed to eliminate excess or deficiency of heat input.

(3) There is no need to increase the rigidity of the equipment in order to obtain cutting accuracy, and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 shows a control system for implementing the invention.

FIG. 2 shows a correlation diagram between welding speed and filler wire supply speed to obtain suitable welding.

FIG. 3 is an explanatory diagram of a cut surface of a strip steel plate.

[Explanation of symbols]

1 Welding gap 2 Welding equipment 3 Control system S strip

Claims (1)

[Claims] Claims: 1. A calculation device is made to store in advance the correlation between wire supply speed and welding speed for each plate thickness in order to obtain appropriate welding conditions for various gap amounts, and the gap amount of the butting surfaces is detected during welding; Butt welding of strips, characterized in that the detected gap amount is input to the arithmetic device, and the wire supply speed and welding speed for the detected gap amount are obtained from the correlation stored in advance in the arithmetic device, and the butt welding is performed. Method.