JPH03114685A - Method for forming butt groove given to laser welding of metallic strip - Google Patents

Abstract

PURPOSE:To smooth the variation of load given to a weld zone and to reduce damage in the weld zone by forming a butt groove in the direction oblique or deviated to an orthogonal line in a plate width direction rectangular to a metallic strip bus line and performing laser welding along the groove. CONSTITUTION:The weld zone 9 is deviated from the orthogonal line L in the plate width direction and, therefore, when the end parts of steel strips 1, 2 are joined by such weld line 9 and rolling-down force is given from the rolls in a rolling mill after welding, rolling-down force by the rolls does not act instantaneously on the weld zone 9, because the rolls are arranged at right angles to the bus line P, in other words, along or in parallel to the orthogonal line L in the plate width direction. Consequently, since the weld zone 9 is rolled gradually in a certain short time, load hardly changes between the weld zone 9 and the steel strip base material, the weld zone 9 does not break, especially, even a steel strip such as high silicon steel does not break.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for forming a butt groove used in laser welding of a metal strip, and more specifically, a method for forming a butt groove for use in laser welding of a metal strip, and more specifically, a method for forming a butt groove by cutting opposing end surfaces of a metal strip and then butting the edges to open the butt groove. When laser welding is performed along this butt U groove, the metal strip is cut so that the cutting line is inclined or deviates from the line perpendicular to the width direction of the metal strip, which is perpendicular to the inner edge. This is a method of forming a butt groove by butt-jointing, in particular, when a metal strip, such as a steel strip, is continuously rolled after being joined by laser welding. Butt (butt) used for laser welding, where the load change is gradual and no breakage occurs in the welded part.
3) Concerning the method of forming the groove.

Note that the metal strip generally includes, for example, a steel plate strip such as a hot-rolled coil, a plate-like material such as a steel plate, and other materials.

Conventional TechnologyRecently, laser beams have been shown to be
Because it is a heat source with a very high energy concentration and at the same time can minimize the heat affected zone, it can be used instead of arc or other heat sources, such as welding in the rolling process of metal strips such as steel plate slips. It is also used for fusing and drilling of cylindrical bodies, etc.

For example, in a continuous rolling line, steel plate strip,
In other words, the opposite ends of the steel strip, that is, the rear end of the leading steel strip and the tip of the trailing steel plate, are cut using, for example, a double cut shear, and then the cut lines are butted against each other. A groove is formed and this is, for example, T I
Both copper strips are joined by welding using G, MIG, etc., and this continuous steel strip is continuously rolled. At this time, the welding method (4) is a welding method with a small beam diameter, low heat input, and a good shape (
Laser welding, which produces beads), is increasingly being used.

In other words, laser welding that uses a laser beam as a heat source can achieve low heat input welding, has a large penetration depth relative to the weld width, and has a particularly low heat-affected zone. It becomes very small, almost non-existent, and a very well-shaped bead is obtained at the weld. For this,
When joining metal strips such as hot-rolled coils to each other and rolling them, if they are joined by laser welding, the weld bead at the joint will be good and the heat-affected zone will be extremely small, so welding will not be possible. The parts can be rolled with almost no hindrance, and the welded parts do not pose any problems in terms of material quality after rolling. However, in order to fully utilize these features of laser welding, it is necessary to increase the energy concentration of the laser beam and to reduce the diameter of the beam focal point of the laser beam using a focusing system such as a lens. . In addition, the butt groove of the steel strip is formed with an extremely small groove gap and high precision in order to fit the narrow diameter of the laser beam. It is necessary to match them well.

From this point on, as a technique for performing the cutting process of copper strips and butting overculm with high precision, for example, Japanese Patent Application Laid-open No. 58-34715 and Japanese Patent Publication No. 62-42730 have proposed techniques for cutting the ends of metal strips with high precision. A technique for cutting with high precision is described. In addition, Jikosho (Publication No. 3138773) describes a technique that butts the cut surfaces after cutting with high precision with almost no clearance. Therefore, according to such a method, high precision cutting and abutment edges can be achieved. can be achieved,
A butt groove suitable for laser welding can be formed, but if the steel type has extremely high deformation resistance, such as high-silicon steel, even if such a butt can be achieved, the weld will break during rolling, making this improvement difficult. It has been demanded.

That is, as mentioned above, the butt grooves that are formed with high precision are always formed parallel to the line perpendicular to the sheet width direction that is orthogonal to the metal strip pass line, and the laser edge tends to be applied along these butt grooves. Therefore, the welded part formed is perpendicular to the sheet width direction or parallel to the metal strip pass line, so the welded part is As soon as a rolling load is applied to the weld, the weld suddenly changes in size, and this sudden load change causes the weld to break.In particular, high-silicon steel, etc. is extremely large, making it easy for the weld to break.

In particular, with conventional 11G and MIG, the bead shape of the welded part is raised and the shape is not good, so the welded part is likely to break during rolling.On the other hand, with laser welding, the bead shape is not good. A well-shaped weld can be obtained, and the weld fracture is significantly less when compared with conventional MIG and King IG, but even in this case, weld fracture occurs with high silicon I4 and the like.

For this reason, in order to prevent the weld from breaking, a method such as grinding the weld (7) with a grinder is carried out to improve the defective shape of the weld (7). This is undesirable because it complicates the work and impairs productivity.

Problems to be Solved by the Invention The present invention aims to solve the above-mentioned drawbacks, and specifically, it provides a butt groove having a shape that does not cause breakage in the welded part even when high-silicon steel, which has high deformation resistance, is laser welded. We propose a method that can form the following.

Means for Solving the Problems and Their Effects Namely, the present invention provides a method of cutting and butting opposing end surfaces of the metal strips on the trailing side by cutting and butting them together, before abutting the metal strips on the trailing side against the metal strips on the leading side and performing laser welding. When forming the grooves, the opposite ends of the metal strips are cut so that each cutting line is inclined or deviates from a line perpendicular to the sheet width direction that is orthogonal to the pass line of these metal strips, and then each cutting line is It is characterized in that it butts together to form a butt groove.

(8) The structure of these means and their operation will be explained in more detail with reference to the drawings as follows.

First, FIG. 1 and FIG. 2 are an explanatory diagram and a plan view of a part of an apparatus for carrying out the method of the present invention in a continuous rolling line,
In this rolling line, the rear end 1b of the steel strip 1 on the leading side
and the tip 2a of the steel strip 2 on the 1st line side are opposed to each other, and then clamped by the Knonzo mechanism 6.7 on the upper side of C1. In this clamped state, both opposing ends 1b and 2a are connected to a tuple cut shear 5 consisting of upper and lower shears 3a, 3b, and 4, for example.
Cut by. After this cutting, each cutting surface or cutting line 1
b' and 2a' are butted together to form a groove, but each cutting line 11I', 28' is configured to be inclined or deviated from the pass line of the steel strip. Therefore, as shown in FIG. 2, each cut 1111)', 2a' is configured as a butt line that is inclined in a straight line obliquely to a line perpendicular to the board width direction. Therefore, when such inclined cutting lines 111' and 2a' are matched,
As shown in FIG. 3, the butt gap Q tip 8 has an inclination angle θ of 4, for example, with respect to a line perpendicular to the board width direction.
5 or less. When a laser beam (not shown) is run along the butt groove 8 thus formed, the weld is not parallel but inclined. 9 can be formed (see FIG. 4).

In other words, this welded portion 9 is aligned with a line 1 perpendicular to the plate width direction. If the ends of the steel strip 1.2 are joined by such a weld line 9, when a rolling blade is applied from the roll in the rolling mill after welding,
The roll is arranged at right angles to the pass line r1, that is, along or parallel to the line perpendicular to the board width direction,
The rolling blade prevents the rolling blade from coming off the welded part 9 instantaneously. In other words, as shown in FIG. 4, since the opening is rolled down at a line perpendicular to the sheet width direction, even if the welding line 9 is reached, that part is the steel strip 1.2, that is, Because it is rolled down together with the base metal, sudden load fluctuations do not occur at the weld (10), and the pressure is applied slowly. Therefore, unlike the conventional example in which the welded part 9 is rolled down instantaneously, it is rolled gradually after a certain period of time, so there is almost no load change between the welded part and the steel strip base material. , the weld is broken! In particular, even copper strips made of high-silicon steel will not break.

Incidentally, the inclination angle θ can take any value as long as it is larger than 0゛, but if it exceeds 45゛, the rollability of the edge of the steel strip will be inhibited, and the inclination angle θ will be 0' to 45''. (However, 0"
) is preferred.

In addition, in order to alleviate load fluctuations in the welded part, as shown in Fig. 5, the cutting line does not need to be formed in an oblique straight line as shown in Fig. [
Two straight inclined lines 10a, 10
It is also possible to form the groove 10 by cutting two pieces together in a chevron shape and butting them against each other. Each slope line 10a at this time.

101), that is, the inclination angle θ1 of each cutting line should be exactly the same, and it is preferable that the inclination angle θ be more than O' and less than 30' (11). Further, as a shearing device, a double cutter, a rotary shear, etc. can be used.

Further, when welding the abutment groove 10 shown in FIG. 5, the direction of the laser torch is changed during welding. In this case, it would be possible to control the movement of the laser torch not only in the horizontal direction parallel to the path line I+ (in other words, in the X direction), but also in the direction perpendicular to the X direction (in other words, in the Y direction). When welding is accomplished in this manner, a welded portion 11 as shown in FIG. 6 can be easily formed.

Note that, as described above, the butt groove is not formed in a straight line (but as shown in FIG. When the laser torch is run in the same manner as described above, it is possible to alleviate the load fluctuations applied to the welded portion during rolling.

Example (12) First, on the continuous rolling line shown in Fig. 1, a butt groove (inclination angle θ-30'') was formed on a thin grain-oriented silicon steel plate (thickness 0.6 mm) as shown in Fig. 2. Then, laser welding was performed using a C02 gas laser welding machine.

On the other hand, as in the conventional example, butt grooves were formed in the width direction of the plate perpendicular to the bus strip and the inside, and laser welding was performed under the same conditions. Thereafter, cold rolling was performed under the same rolling conditions, and the fracture rate at the welded part was compared, and was 30% in the method of the present invention, but 50% in the comparative example.

(Effects of the Invention) As explained in detail above, the method of the present invention is a method in which, prior to laser welding the metal strips and joining them together, the ends of the metal strips butt against each other to form a butt groove. Then, a butt groove is formed in a direction perpendicular to the sheet width direction that is perpendicular to the metal band pass line, and a butt groove is formed in the direction of the metal strip, and while the laser torch is running along this butt groove. , characterized by laser welding.

Therefore, during continuous rolling after laser welding, the load applied to the welded part changes slowly, and the possibility of breakage of the welded part can be greatly reduced.

[Brief explanation of drawings]

1 and 2 are an explanatory diagram and a plan view of a part of the apparatus for carrying out the method of the present invention in a continuous rolling line, FIG. 3 is a plan view of an example of a butt groove used in the method of the present invention, and FIG. 4 5 is a plan view of another example of the butt groove used in the method of the present invention, FIG. 6 is a plan view of the weld portion, and FIG. 7 is a plan view of another example of the butt groove used in the method of the present invention. FIG. 3 is a plan view of an example butt groove. Code 1.2... Leading and trailing steel strips 3...
...Double cut shear 8.10.12...Butt bevel 9.11.
・・・・・・Welding part (14)

Claims (1)

[Claims] 1) Prior to butting and laser welding the leading and trailing metal strips, when the opposing end surfaces of these metal strips are cut and butted to form a butt groove, these metal strips are The opposing ends of the metal strip are cut so that each cutting line is inclined or deviates from a line perpendicular to the plate width direction that is orthogonal to the pass line of the strip, and then each cutting line is butted to form a butt groove. A method for forming a butt groove for laser welding of a metal strip, characterized in that: 2) Cut the opposing ends of the metal strip so that each cutting line is linearly inclined with respect to the line perpendicular to the plate width direction, and then,
2. The method of forming a butt groove for laser welding of a metal strip according to claim 1, wherein the butt groove is formed by butting each cutting line. 3) It is characterized by inclining linearly with respect to the line orthogonal to the board width direction, so that the inclination angle during cutting and butting is in the range of 0° (however, 0° is not included) to 45°. A method for forming a butt groove for laser welding of a metal strip according to claim 2. 4) Cut the end of the metal strip so that the two inclined lines, each of which is linearly inclined with respect to the line perpendicular to the plate width direction, are combined to form a chevron shape, and then cut each cutting line. 2. The method for forming a butt groove for use in laser welding of metal strips according to claim 1, wherein the metal strips are butted to form a butt groove. 5) The inclination angle when cutting and butting is 0° (however, 0° is not included) so that the two inclined lines are inclined linearly with respect to the line orthogonal to the board width direction to form a mountain-shaped shape. ~3
5. The method of forming a butt groove for laser welding of a metal strip according to claim 4, wherein the groove is formed in a range of 0°. 6) The opposing ends of the metal strip are cut so that each cutting line is offset from the line perpendicular to the plate width direction and at least a portion forms an arc, and then butted against each other to form a butt groove. A method for forming a butt groove for laser welding of a metal strip according to claim 1.