JP2745332B2 - Laser butt welding method and apparatus for steel strip - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for laser butt welding of a steel strip, specifically, a plate thickness of 0.5 mm or less,
It is a thin object of about 0.15mm or less and the board width is 1.0m
The present invention relates to a welding method and a laser welding method capable of reliably butting a steel strip having a width as large as or larger than the whole width with high precision and performing laser welding satisfactorily.

2. Description of the Related Art Conventionally, in a continuous steel strip processing line, steel strips are joined by butt welding to continuously perform rolling and other processes. Before the steel strip is supplied as a product to the customer, it is subjected to, for example, rewinding, winding, welding, slitting, cutting, etc., and in particular, the steel strip as a product is continuously joined by butt welding. The continuous steel strip is slit according to the unit weight required by the customer and sent out as a product. Above all, in this case, strict welding quality is required, since the steel sheet is sent out with little care thereafter.For example, in the case of a silicon steel strip, the power loss decreases as the sheet thickness becomes thinner. 0.
Rolled to about 15mm or less, ultra-thin products are required,
It is required to weld this ultra-thin state, and it is required to obtain a high-quality welded part which does not require subsequent care during this welding.

That is, when welding to join the silicon steel strips, when forming the butt groove, the cut section of the steel strip cut prior to welding is straight and linearly displaced, bent, etc. Not required.

The directional silicon steel strip tends to be reduced in thickness from about 0.35 to 0.30 mm to about 0.30 to 0.10 mm from the viewpoint of reduction in power loss.

For this reason, laser welding, which has a high energy density and can reduce the beam diameter, has been applied to silicon steel strip welding instead of TIG, MIG, and the like. That is, in the case of laser welding, the beam diameter can be reduced to about 0.1 mm, and accordingly, the energy density can be increased and the heat affected zone (HAZ) can be reduced.

However, thin steel strips are compatible with laser welding. In other words, it is extremely difficult to form a groove that can fully demonstrate its characteristics, and particularly at the welding start and end, burn-through easily occurs. If the butting of the surfaces is not perpendicular and straight to the steel strip pass line, and is not adjusted flat without waving in the thickness direction, the quality of the welded joint will be impaired. It often breaks at welded joints during processing, and its breaking rate reaches 50% or more.

From this point, as shown in Japanese Patent Application Laid-Open No. 61-276793, both opposing ends of the preceding steel strip and the following steel strip are overlapped, and the overlapped portion is cut by a rotary grinding wheel in a clamped state. A method of forming a groove by abutting cut surfaces with each other is described.

However, according to this method, abutment of a gap of substantially zero can be achieved, but a large amount of scrap is generated from the overlapped portion every time cutting is performed, which wastes material and takes time and effort to remove the scrap. If the cutting is not performed, it takes time to perform the matching due to the occurrence of burrs, drooling, and the like.

Further, a laser butt welding apparatus for a steel strip described in Japanese Patent Application Laid-Open No. 62-230491 is provided with fixed clamps on both sides of a laser torch after cutting opposite ends of a preceding steel strip and a following steel strip. In addition, a moving clamp device is provided, and the moving clamp device is configured to be movable by a numerical control motor in the direction of the steel strip pass line, while transferring the succeeding steel strip toward the cut surface or the butt surface of the preceding steel strip. This is a laser butt welding apparatus configured so that the rotation drive of a pinch roll can be controlled by a numerical control motor.

In this apparatus, movement of both steel strips in the direction of the pass line is controlled with high precision, and accurate butting can be achieved. However, in the case of a thin plate, prevention of warpage in the thickness direction is insufficient. That is, in this welding apparatus, at the time of butting, the cut surfaces of both steel strips are sucked by the electromagnetic chuck provided on the work table, so that warpage or the like can be absorbed. However, the provision of the electromagnetic chuck increases the size of the apparatus and complicates the mechanism, and the steel strip is also excited, so that the fine movement of the steel strip becomes difficult, so that accurate butting cannot always be achieved.

Problem to be Solved by the Invention The present invention aims at solving the above-mentioned drawbacks, and specifically, when cutting a thin steel strip having a thickness of about 0.1 to 0.6 mm and laser welding, The present invention proposes a method and a device capable of accurately but precisely abutting both steel strips and laser welding the two steel strips.

Means for Solving the Problems and Action Therefor In other words, the laser butt welding method according to the present invention is to cut the opposing ends of the preceding steel strip and the following steel strip, and then butt these cut surfaces as butt surfaces to form a butt groove. When laser welding is performed by running a laser welding torch along the butt groove, after cutting the opposing ends of the preceding steel strip and the following steel strip, the preceding steel strip and the following steel strip are cut. It is characterized in that tension is applied to both cut portions of the strip in the sheet width direction orthogonal to the steel strip pass line, and both cut surfaces are abutted in this tension state.

Also, an apparatus suitable for performing this method is to cut the opposing ends of the preceding steel strip and the following steel strip, and then butt these cut surfaces as a butt surface to form a butt groove. In a laser butt welding apparatus for a steel strip that performs laser welding along a butt groove, a leading clamp apparatus that clamps ears at both ends of a cutting section of a preceding steel strip, and a clamp apparatus that clamps ears at both ends of a cutting of a succeeding steel strip. A row clamp device, and in each of the preceding and following clamp devices, each of the opposed clamp pieces is configured to be movable in a direction parallel to the steel strip pass line and in a plate width direction orthogonal to the steel strip pass line. It is characterized by.

Therefore, the configuration and operation of these means will be described more specifically with reference to the drawings as follows.

FIG. 1 and FIG. 2 are a plan view and a side view of an example of a device for carrying out the present invention, FIG. 3 is an explanatory view showing a part of the clamping device in cross section, and FIG. a) and (b) are explanatory diagrams of an example of warpage of a steel strip and an explanatory diagram of an example in which the warpage is corrected by the present invention, and FIG. 5 is a plan view showing an example of a groove line in the present invention. .

First, in FIG. 1 and FIG. 2, prior to joining the preceding steel strip 1 and the following steel strip 2 to each other by laser welding on the continuous rolling line of the steel strip, for example, the upstream side of the continuous rolling line Prior to performing the laser welding, the opposite ends of the preceding and following steel strips 1 and 2 are cut. That is, the rear end of the preceding steel strip 1 and the front end of the succeeding steel strip 2 are opposed to each other, and these opposed ends are clamped from above and below. Cut at the same time by a shear.

Next, after cutting in this manner, FIGS.
As shown in the figure, a butt groove is formed by using the cut surfaces 1a and 2a of the preceding steel strip 1 and the succeeding steel strip 2 as butt surfaces. At this time, each of the cut surfaces 1a and 2a has A tension is applied in a thickness direction orthogonal to the pass line P, and the cut surfaces 1a and 2a facing each other are abutted in this tensioned state, and the laser torch 3 is moved along the abutting groove to perform laser welding.

That is, for example, when the steel strip is extremely thin, such as a sheet thickness of about 0.1 to 0.6 mm, the steel strips 1 and 2 may be used at the time of abutting.
For example, as shown in FIG. Even in the state of waving in this manner, both cut surfaces 1a, in a state where the groove formed matches the plate width direction which can be orthogonal to the pass line P, and the linearity with high precision is maintained. 2a
Can be matched, and this groove coincides with the travel line of the laser torch 3. However, each cut surface
Even if 1a, 2a or the butt groove exactly matches the width direction of the plate perpendicular to the pass line P, when there is wavy or warped in the thickness direction, uniform penetration cannot be obtained over the entire length of the groove line. As a result, the joint strength of the weld decreases. Therefore, when the steel strips 1 and 2 are joined with such a welded joint, the welded portion breaks during the rolling process, and the breaking rate becomes extremely high.

On the contrary, in the present invention, the cut surfaces of the steel strips 1 and 2 are used.
When the steel strips 1a and 2a are pulled at the ears at both ends, the thickness and thickness of the steel strip are small. In the pulled state, the waving and warpage are corrected as shown in FIG. 4 (b). Therefore, when the cut surfaces 1a and 2a are abutted against each other in a tensile state, a uniform penetration is obtained over the entire length of the groove line, and a sufficient joint strength can be maintained at the welded portion. For this reason, even if a large rolling force is applied to the welded portion during rolling, it hardly breaks, and the breaking rate can be greatly reduced.

Further, as described above, when tension is applied to both cut surfaces 1a and 2a, the preceding clamp device 4 and the following clamp device 5 are provided to individually clamp each cut surface 1a and 2a. These clamping devices 4 and 5 are composed of clamp pieces 4a, 4b, 5a and 5b, and a pair of clamp pieces 4a and 4b are used to secure the leading steel strip 1 to the steel strip 1.
Clamp both ends of the cut surface 1a, and a pair of clamp pieces
5a and 5b clamp the both ends of the succeeding steel strip 2.
Therefore, when the opposing clamp pieces 4a and 4b are moved in the preceding clamp device 4 in the plate width direction orthogonal to the steel strip pass line P so as to move away from each other, FIG.
As shown in the figure, the cut surface 1a of the preceding steel strip 1 is pulled. Similarly, in the succeeding clamp device 5, both clamp pieces
The cut surface 2a of the succeeding steel strip 2 is pulled by the movement of 5a, 5b.

Further, in the preceding and following clamping devices 4, 5, each of the clamp pieces 4a, 4b, 5a, 5b is in a direction parallel to the steel strip pass line P, that is, in the pass line direction or the direction orthogonal to the steel strip pass line P, It is configured to be able to move in the plate width direction. Each of these two-way moving mechanisms can be configured, but the plate width moving direction to be moved in the direction perpendicular to the pass line P is the hydraulic cylinders 6a, 6b, 7a, 7b for the respective clamp pieces 4a, 4b, 5a, 5b. The moving mechanism parallel to the pass line P is composed of traveling vehicles 8a, 8b, 9a, 9b and hydraulic cylinders 10a, 10b, 11a, 11b.
That is, each of the clamp pieces 4a, 4b, 5a, and 5b is configured so that the upper clamp piece can be moved up and down as described later. , 7a, 7b each clamp piece 4a,
4b, 5a and 5b are individually moved in the plate width direction.
These hydraulic cylinders 6a, 6b, 7a, 7b are respectively arranged on the traveling vehicles 8a, 8b, 9a, 9b, and the traveling vehicles 8a,
9a is made to travel along one rail track 12 provided in parallel with the pass line P, and the other carriages 8b and 9b are made to travel along the other rail track 13. This running force is the
Hydraulic cylinders 10a, 10b, 11 individually for 8a, 8b, 9a, 9b
Provide a and 11b.

With this configuration, each of the clamp pieces 4a, 4b, 5a, 5b
Can reliably and individually travel in a plate width direction orthogonal to the pass line P and in a direction parallel to the pass line P, and the butting as described above can be achieved. Each clamp piece 4a, 4b, 5
3, a and 5b are configured as shown in FIG. 3 so that the upper clamp piece is moved up and down by the hydraulic cylinder 13 so that the lugs of the steel strips 1 and 2 can be clamped.

That is, prior to joining the opposing ends of the preceding and succeeding steel strips 1 and 2 by laser welding, each opposing end is cut by, for example, a double cut shear, and thereafter, both the steel strips 1 and 2 are cut. Connect the ears to each clamp piece 4a, 4b, 5a, 5b
Clamp with. At this time, in the state shown in FIG. 4 (a), the clamp pieces 4a, 4b, 5a, 5b are moved in the direction away from each other by the hydraulic cylinders 6a, 6b, 7a, 7b, and the state shown in FIG. 4) to the state shown in FIG. 4 (b). After that, each traveling cart 8a, 8b, 9
The laser welding is carried out by running the laser torch 3 along the grooves by forming the butt groove so as to coincide with the traveling line of the laser torch 3 by running the a and 9b.

Regarding the treatment of both end portions of the welded joint, there are the following two methods.

In other words, when joining completely to both ends, the clamping position is shifted by an appropriate distance from the end of the steel strip to the anti-welding tip side, so that the steel strip is abutted with the preceding steel strip side clamp. The necessary gap is provided between the subsequent steel strip side clamps, and the welding torch can be run to perform welding from end to end of the groove. However, in this method, the tension effect of the groove by the clamp is reduced.

Therefore, the clamp grips the corner of the steel strip as much as possible to maximize the tension effect of the bevel line, does not weld the clamp part, cuts out in a circular arc shape with a notch after welding,
It prevents a source of breakage in the subsequent rolling process. This state is shown in FIG. 5, where reference numeral 15 is a notcher, and reference numeral 16 is a notched line. After welding, the spliced steel strip is sent in the direction of the pass line P to perform predetermined rolling.

Example After a steel strip having a thickness of 0.5 mm was cut by a conventional method, each cut surface was pulled in the width direction of the plate by the apparatus shown in FIGS. 1 and 2 and butted in this state. Laser welding was performed by running a laser torch along the butt groove, and then cold-rolled continuously by a conventional method. At this time, the fracture rate of the weld was determined to be 20%.

For comparison, a butt groove was formed by a conventional method, and laser welding was performed under the same conditions. As a result, the fracture rate of the welded portion was 50%.

<Effects of the Invention> As described in detail above, prior to laser welding the preceding steel strip and the following steel strip, the present invention cuts the opposite ends of the preceding steel strip and the following steel strip, It is characterized in that a tension is applied to the cut portion in a plate width direction orthogonal to the steel strip pass line, and both cut surfaces are abutted in this tension state.

Therefore, if the steel strip according to the conventional example is a thin steel strip, a height deviation in the thickness direction due to some shape defect occurs at the time of abutting, and poor welding occurs. Although the entire width is not clamped, the shape of the welding surface becomes flat, the height deviation at the time of butt can be reduced, and the weldability is improved.

[Brief description of the drawings]

1 and 2 are a plan view and a side view of an example of a device for carrying out the present invention, FIG. 3 is an explanatory view showing a part of the clamping device in a cross section, and FIGS. 4 (a) and (b). Is an explanatory view of an example of warpage of a steel strip and an explanatory view of an example in which the warp is corrected by the present invention, and FIG. 5 is a plan view showing an example of a groove line in the present invention. Reference numeral 1: Leading steel strip 2 ... Trailing steel strip 1a, 2a ... Cut surface 4 ... Leading clamp device 5 ... Trailing clamp device 4a, 4b, 5a, 5b ... Clamp piece 15 ... Notch 16 ... Notched line P ... Steel strip pass line

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Koichi Hirase 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. JP-A-62-263887 (JP, A) JP-A-61-276793 (JP, A) JP-A-62-230491 (JP, A)

Claims (3)

(57) [Claims] After cutting the opposing ends of a preceding steel strip and a following steel strip, these cut surfaces are butted as a butt surface to form a butt groove, and then a laser welding torch is formed along the butt groove. When running and laser welding, after cutting the opposite ends of the preceding steel strip and the following steel strip, both cutting portions of the preceding steel strip and the following steel strip are orthogonal to the steel strip pass line. Apply tension in the board width direction,
A laser butt welding method for a steel strip, wherein both cut surfaces are butted in this tension state. 2. In both cutting portions of the preceding steel strip and the following steel strip, the lugs are clamped and welded by applying tension in a sheet width direction orthogonal to the steel strip pass line. 2. The method according to claim 1, wherein the steel strip is notched in an arc after welding without welding. 3. After cutting the opposing ends of the preceding steel strip and the following steel strip, these cut surfaces are butted as a butt surface to form a butt groove, and then laser welded along the butt groove. In the laser butt welding apparatus of the steel strip, a leading clamp device that clamps the ears at both ends of the cutting portion of the preceding steel strip, and a trailing clamp device that clamps the ears at both ends of the cutting of the following steel strip, In these leading and trailing clamping devices, each of the opposed clamp pieces is configured to be movable in a direction parallel to the steel strip pass line and in a sheet width direction orthogonal to the steel strip pass line. Laser butt welding equipment.