JPH0299289A - Method for setting laser beam irradiating position in laser beam welding - Google Patents

Abstract

PURPOSE:To surely set the laser beam irradiating position by spot-irradiating at least two points on the butting line of steel strips with a laser beam and subjecting gaps between the two points to laser beam welding and then, inspecting and correcting the projection position. CONSTITUTION:A preceding steel strip S1 and a succeeding steel strip S2 are clamped respectively by clamps 4 and 5 and an each steel strip end is cut by a double-cutting shear 6 and these are abutted on each other by the inlet side clamp 5. The spot irradiations P1, P2 and P3 of the laser beam are then performed on three points of the lateral directional ends and central position of the steel strips. Continuous weldings W1 and W2 are then performed on the gaps between the spot projection parts. Afterward, when the spot irradiating parts are observed from the rear, the butting line and the spot irradiation position are coincident with each other on the spot irradiation P1 but the spot irradiating positions are deviated from the butting line on the spot irradiations P2 and P3. The satisfactory welding work can be then performed by giving a correction command for the above-mentioned deviation to the travel control system of a laser beam torch.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for setting a laser beam irradiation position when butt welding metal strips by laser welding.

<Prior Art> When butt welding metal strips such as stainless steel strips and silicon steel strips, laser welding, which can perform welding with low heat input and high energy density, is increasingly being used as a welding method.

Fig. 3 schematically shows a laser welding machine for metal strips.
is a laser torch. Further, 4 is an entry side clamp, 5 is an exit side clamp, and 6 is a double cut shear, all of which are provided on the pedestal 7.

FIG. 4 is a diagram schematically showing the three parts of the laser torch, in which 8 is a reflecting mirror, 9 is a condensing mirror, and 10 is a laser beam.

Now, when welding the leading strip S1 and the trailing strip S2, first, the end of each strip S, S, is manually clamped with the exit clamp 4.5.Then, the end of each strip is cut with the double cut shear 6. do. After cutting, the shear 6 is evacuated offline, and the strip S is clamped by the input clamp 4 and moved to the output clamp 5 side to butt the strips together, and then the laser torch 3 is moved to the butt line 11. Welding is performed by moving the laser beam IO focused by the condensing mirror 9 while irradiating the weld along the weld. 12 is a welded portion formed by this welding.

One of the important management items in such laser welding is the irradiation position of the laser beam with respect to the metal strip. This irradiation position has a height direction position and a position in the horizontal plane. The height direction position refers to the focal position of the condensed laser beam, and proposals for this control have been made, such as in Japanese Patent Publication No. 6033593.

On the other hand, the position in the horizontal plane refers to the irradiation position with respect to the butt line, and the focal diameter of the focused laser beam, which must be at an appropriate position over the entire width of the strip, varies depending on the output, but is generally 0. The size is about .1 to 0.4 cylinders, and precision is required for positioning.

The following method is used to confirm the irradiation position of the laser beam in the horizontal plane. In other words, butting the strips! 91i Experimentally perform laser welding by accidentally changing the laser beam irradiation position in the direction perpendicular to i, perform mechanical tests such as Erichsen tests, and adjust the irradiation position to obtain the maximum intensity. was.

FIG. 5 shows an example of the results of this test. The horizontal axis represents the irradiation position of the laser beam, and the irradiation position before the start of the check is taken as the reference point (zero point).

The vertical axis is the Erichsen test value, with the maximum strength being 1.0.

From this, the current irradiation position is sufficient because the irradiation position is within the range where the maximum intensity can be obtained, but furthermore to the positive side, 3+ (-0, 2) l / 2 = 0.05
Well, it turns out it's a good idea to move the laser torch.

In addition to the above method, the irradiation position can be confirmed by irradiating the laser beam spot-wise and observing the melting state in the spot-irradiated areas on the front and back surfaces in this state, that is, with the strip clamped. There is a way to do that.

<Problems to be Solved by the Invention> However, the former method using mechanical testing has a problem in that it takes a very long time.

Also, the latter method using spot irradiation is shorter in time than the former method, but when the restraint by the clamp is removed, the strip S...S! Since the parts separate, the work must be done in a clamped state, that is, work must be done inside a laser welding machine, which poses problems in terms of workability and safety. Furthermore, there is also the problem that when it becomes necessary to collect a sample, this sample cannot be collected. Further, even if the strip is at a proper position at one point in the width direction, there is no guarantee that the strip will be in good condition over the entire width.

The present invention has been made in view of the problems of the prior art described above, and it is an object of the present invention to provide a method for easily and reliably setting the irradiation position of a laser beam.

Means for Solving the Problems> The present invention, when butt welding the ends of two metal strips together by laser welding, spot-irradiates at least two points on the butt line of the metal strips with a laser beam, and then After performing laser welding between the spot irradiation points, the position of the spot irradiation point and the butt line of the metal strip is inspected to correct the irradiation position of the laser beam.

Function> The present invention will be explained in detail based on FIG. First, the ends of the leading strip S1 and the trailing strip S8 are cut and butted together. Then, spot irradiation P1, P2, P is performed from one end along the butt line 11, in this case,
Pl-Ps is approximately the end portion in the width direction of the strip, and P is the center portion. Then, normal continuous welding and Wt are performed between the spot irradiation points P1 and P2 and between P2 and Ps.

This welding part -1, h allows the leading and trailing strips S1
, S, are firmly connected, so that each strip S1, S2 will not separate even when the clamp is opened, and this abutment can therefore be transported to the output side 3 of the laser welding machine. Then, the spot irradiation position can be easily checked on the output side of the welding machine.

For spot irradiation in 22, if the output of the laser beam is low,
Since the melted part does not appear on the back side, the irradiation position cannot be confirmed, and if the output is high, the melted part becomes large, making it impossible to check the irradiation position.This also applies to the irradiation time. From this, if the thickness of the metal strip is 3.0 or less, the output will be 0.5 to 1.0 kW.
The irradiation time must be appropriately selected within the range of 0.5 to 1 second.

<Example> The method according to the present invention was carried out using a rope rope having a plate thickness of 2.0 mm and a plate width of 1200 mm.

First, the leading steel strip S and trailing steel strip S2 of the above dimensions are clamped by the clamp 4.5 shown in FIG. The butt was made using side clamps 5.

Next, as shown in FIG.
Output 1.0 at 3 locations: mm position and width direction center position
Spot irradiation P1, P2, P, kW, irradiation time 1 second,
Next, the laser output was set to -10, and continuous welding was carried out between these spot irradiated parts, each having a length of about 450 mm. After that, release the clamp etc.
The welded copper strip was transported to the exit side of the laser welding machine, but the welded part did not break.

When the spot irradiation area was observed from the back side, it was as shown in FIG. That is, spot irradiation P at one end,
In this case, the butt line and the spot irradiation position matched, but the position of the spot irradiation P2 at the center was shifted by about 0.15 heel, and the spot irradiation P at the other end was shifted by about 0.3 heel.

Therefore, when we gave a correction command for this deviation to the travel control system of the laser torch, we were able to perform good welding work.

In addition, although the above explanation was based on performing spot irradiation three times, it is sufficient if the spot irradiation is performed two or more times.

<Effects of the Invention> As explained above, according to the present invention, the irradiation position of the laser beam can be set accurately in a short time, and the work can be performed safely. Therefore, in a continuous metal strip processing line, the rear end of the leading strip and the leading end of the trailing strip are simultaneously sheared using a double cut shear to form a butt groove, and this butt groove is laser welded. It is particularly effective when high work efficiency and accuracy are required. Furthermore, since welding is also performed, there is the advantage that we can also collect samples of welded parts.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the principle of the present invention, and FIG. 2 is a plan view of an embodiment of the present invention. FIG. 3 is a perspective view schematically showing the entire laser welding machine for metal strips, and FIG. 4 is a perspective view schematically showing the laser torch portion of the laser welding machine for metal strips. FIG. 5 is a graph showing an example of the relationship between the laser beam irradiation position and the Erichsen test value in the conventional laser beam irradiation position setting method. DESCRIPTION OF SYMBOLS 1... Laser beam oscillator, 2... Laser beam transmission system, 3... Laser torch, 4... Inlet side clamp, 5
...Outside clamp, 6...Double cut shear 7
... Frame, 8... Reflection mirror 9... Concentrating mirror 10... Laser beam, 11... Butt line, 12... Welded part, Sl... Leading strip, S, ... Trailing strip, Pls Pt,
Ps...Spot irradiation point. Figure Figure

Claims (1)

[Claims] When butt welding the ends of two metal strips together by laser welding, at least two points on the butt line of the metal strips are spot-irradiated with a laser beam, and then, after laser welding between the spot irradiation points, the spot A method for setting a laser beam irradiation position in laser welding, the method comprising: inspecting a position between an irradiation point and a butt line of the metal strip, and correcting the laser beam irradiation position.