JPH04367304A - Welding method utilizing laser beam for plates for rolling - Google Patents

Abstract

PURPOSE:To reduce welding energy consumption and to reduce rupture of a weld zone by making the quantity between different levels of the upper surface smaller than or equal to that of the lower surface in the height of the upper and lower surfaces of a preceding plate and a succeeding plate and performing welding. CONSTITUTION:In welding the respective ends of the preceding plate Sa and the succeeding plate Sb having the different thickness utilizing a laser beam, laser beam welding equipment having a mechanism to adjust the height of the upper and lower surfaces of the preceding plate Sa or the succeeding plate Sb is used. The quantity between different levels of the upper surface is made almost equal to or smaller than that of the lower surface in the relation in height between the upper and lower surfaces of the preceding plate Sa and the succeeding plate Sb and welding is performed. Consequently, the welding speed can be increased and capacity is increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method for joining the rear end of a leading plate and the tip of a trailing plate during rolling of metal plates to obtain strips.

0002

[Prior Art] Conventionally, in laser welding of such metal plates, a leading plate a and a trailing plate b are used, as shown in FIG.
Laser beam L is applied with the bottom surfaces of each plate aligned.
Run the machine to perform welding.

[0003] At this time, as shown in the same figure, if the thicknesses of the leading plate a and the trailing plate b are different, if the laser light source is located on the upper side, the welding part w does not exist on the other side. The step d is also formed, resulting in extra welding energy consumption.

[0004] High welding energy means that the welding speed (laser head speed) is slow, that is, the welding time is long, which inevitably reduces the throughput of the entire rolling line.

[0005] Furthermore, Japanese Patent Laid-Open No. 59-92180 discloses a method in which the center lines of the thicknesses of a leading plate and a trailing plate, which have different thicknesses, are aligned. However, the invention described in this publication relates to flash butt welding, and the welding method is different from laser welding, which is the object of the present invention, and the purpose of adjusting the height direction positions of the leading plate and trailing plate is different.

[0006]

[Problems to be Solved by the Invention] The present invention aims to reduce the energy required for welding when joining the respective ends of a leading plate and a trailing plate by laser welding during strip rolling, and to improve the processing capacity of a rolling line. The purpose is to improve

[0007]

[Means for Solving the Problems] The present invention provides a means for increasing the height of the upper and lower surfaces of a leading plate or a trailing plate when laser welding the respective ends of a leading plate and a trailing plate having different thicknesses during strip rolling. Using a laser welding device that has a mechanism to adjust the height, the height relationship between the top and bottom surfaces of the leading and trailing plates is welded so that the height difference on the top surface is approximately equal to or smaller than the height difference on the bottom surface. It is characterized by doing the following.

[0008]

[Operation] FIG. 1 is a diagram showing the operation of the method of the present invention when a laser light source is placed above.

When the upper surfaces of the leading plate Sa and the trailing plate Sb are aligned and welded as shown in FIG.
As shown in b), the welding area w when the leading plate Sa and the trailing plate Sb are welded with their centers coincident is compared to the welded area w when their lower surfaces are aligned and welded as shown in FIG. It was confirmed that the amount decreased considerably. The amount of energy required for welding can be reduced accordingly.

[0010] In addition, the trimming necessary to prevent the weld from breaking when materials with different thicknesses pass through equipment downstream of the welding equipment is important when the centers of both plates are aligned. Since there is no vertical unevenness and the amount of trimming is small, uniform and stable trimming is possible, and as a result, the uniformity of the connection after trimming is increased.

[0011]

[Embodiment] An embodiment in which the present invention is applied to rolling a steel plate strip will be described.

FIG. 5 shows an example of the configuration of a production line to which the welding method of the present invention is applied.

[0013] After the edges of the leading plate and trailing plate of the rolling plate S unwound by the unwinding device 11 are welded by the laser welding device 12, when rolling plates of different thicknesses are welded, a trimming device is used. At step 13, the welded portion is trimmed to prevent it from passing through the loop device 14 and rolling device 15 with the step still attached. If you pass through these devices with steps,
There is a high possibility that the weld will break. In the figure, 16 is a cutting device, and 17 is a winding device.

FIG. 2 is a perspective view showing essential parts of the laser welding device 12, FIG. 3 is a perspective view showing a back bar of the welding device, and FIG. 4 is a front view showing the arrangement of the back bar.

In these figures, 1a is a clamping device for the leading plate Sa, and 1b is a clamping device for the trailing plate Sb. Note that the upper clamp plate is not shown in FIGS. 2 and 3. A back bar 2 receives the laser beam L from below, and is arranged between the clamp devices 1a and 1b.

The clamp device 1b on the entry side can adjust the surface height of the lower clamp plate by a height adjustment mechanism consisting of a wedge 3 and a cylinder 4, and the height of the trailing plate Sb can be adjusted by adjusting the height of the trailing plate Sb. It can be adjusted to the plate Sa. Note that the upper clamp plate has a structure in which it is pressed from above by a cylinder (not shown).

As shown in FIG. 3, the back bar 2 includes a back bar 2a for the leading plate Sa and a back bar 2 for the trailing plate Sb.
As shown in the figure, the surface height of the back bar 2b can be adjusted by a height adjustment mechanism consisting of a wedge 5 and a cylinder 6. There is.

In addition, in FIGS. 2 and 3, the heights of the entry side clamping device 1b and the trailing board back bar 2b are adjusted, but the heights of the exit side clamping device 1a and the leading board back bar 2a are adjusted. It is also possible to adopt a configuration in which the height is adjusted.

Now, for example, if the thickness of the rolling plate S is 3 mm for the leading plate Sa and 4 mm for the trailing plate Sb, the welding amount when welding the lower surfaces of both plates so that they are aligned (as shown in FIG. 6) is When welding with the top surfaces aligned (Fig. 1(a))
The welding amount is approximately 80% when welding (in the case of Fig. 1(b)), and approximately 90% when welding with the centers aligned (in the case of Fig. 1(b)), and as a result, the laser head traveling speed that can be welded is It increases in inverse proportion to (the amount of metal to be melted).

On the other hand, as described above, the best trimmability is achieved when the centers of both plates are aligned.

[0021] From the above, as a specific embodiment, it is most preferable to adjust the height so that the centers of both plates coincide, taking into consideration welding speed and trimming performance.

However, depending on the material to be treated, welding efficiency may be more important, and in such cases, it is better to adjust the heights so that the upper surfaces of both plates are aligned. As a specific method, for example, the height adjustment allowance is calculated based on the following formula: △tu=△t×K △tu: Level difference on the top surface △t: Plate thickness difference K: Coefficient (0≦K≦0.5) In addition, the coefficient K may be selected depending on the specific circumstances such as the material.

When the present inventors verified the laser head traveling speed that can be welded using an actual device, it was found that the leading plate thickness was 5 mm, the trailing plate thickness was 4 mm, and the laser output was 10 KW.
In the case of , the welding speed is 4.2 mpm in the conventional method in which the bottom surfaces of both plates are aligned, and 4.7 mpm in the case of the inventive method in which the centers of both plates are aligned, resulting in a welding speed improvement effect of over 10%. Obtained.

[0024]

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

(1) Less welding energy is required, welding speed can be increased, and throughput is increased.

(2) Compared to conventional welding methods, the difference in level between the leading plate and the trailing plate can be made smaller, and trimming can be made more uniform, which reduces the chance of breakage of the welded part due to bending during rolling or threading.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the effect of the present invention by a welding area.

FIG. 2 is a perspective view showing essential parts of a laser welding device according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a back bar of the welding device.

FIG. 4 is a front view showing the arrangement of the back bar.

FIG. 5 is a configuration example of a production line to which the present invention is applied.

FIG. 6 is a diagram illustrating a conventional method.

[Explanation of symbols]

1a, 1b Clamp device 2, 2a
, 2b Back bar 3, 5 Wedge
4,6 Cylinder 11 Rewinding device
12 Laser welding device 13 Trimming device 14
Loop device 15 Rolling device
16 Cutting device 17 Winding device S Rolling plate
Sa Leading board Sb Trailing board
L Laser beam w Welding part

Claims (1)

[Claims] Claim 1: A laser having a mechanism for adjusting the height of the upper and lower surfaces of the leading plate or trailing plate when welding the respective ends of the leading plate and trailing plate having different thicknesses by laser during strip rolling. Rolling characterized by performing welding using a welding device so that the height relationship between the upper and lower surfaces of the leading plate and the trailing plate is such that the height difference on the top surface is approximately equal to or smaller than the height difference on the bottom surface. Laser welding method for plates.