JP2000158165A - Jointing method of steel belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel belt jointing method which is advantageous in welding quality and productivity when three different kinds of steel belts are jointed to manufacture a steel belt used for a tailored blank method. SOLUTION: In this jointing method, when edge parts of three different steel belts 1, 2, and 3 are continuously welded, laser welding is performed while a width directional force is applied to the steel belts by passing the steel belts 1 and 2 between a welding roll and plural inclined presser rolls so as to work a pressurizing force on edge part ends of the steel belts 1 and 2. Then, laser welding is performed while a width directional force is applied to the steel belts by passing the welded steel belts 1 and, 2, and the steel belt 3 between the welding roll and the plural inclined presser rolls so as to work a pressurizing force on edge part ends of the steel belts 1, 2, and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining steel strips for press forming by welding a plurality of steel strips having different thicknesses, strengths, or properties to the ends in the longitudinal direction. .

[0002]

2. Description of the Related Art Conventionally, in the production of automobile parts, for each automobile part requiring formability such as deep drawing or stretch forming or an automobile part requiring high strength, a steel sheet corresponding to the requirement is press-formed. However, some automotive parts have parts that require strict moldability and parts that do not require moldability. There is an automobile part or the like having a part where high strength is not required. Conventionally, when manufacturing such an automobile part, an automobile is manufactured by press-forming using a single steel sheet that can withstand the required performance and welding the formed automobile part.

Recently, in the production of automobile parts, in order to provide necessary thickness and strength to necessary parts,
A method called so-called tailored blank, in which steel sheets having different thicknesses or strengths are joined by a laser or the like to form a single steel sheet and then integrally provided for pressing, has been attracting attention. JP 7
-290182 and JP-A-8-174246. A method of butt welding galvanized steel strips with a laser beam is also disclosed in Japanese Patent Publication 5-255.
No. 96 and the like.

[0004]

However, in a method of forming an automobile part using a single steel sheet of the same material, excellent formability is required even in a part where the formability required for the molded automobile part is not so required. Will have
In other words, there is a problem that the material is over-action and the cost of the material increases accordingly. Further, the tailored blank method known from JP-A-7-290182, JP-A-8-174246, and the like, shears a steel sheet into a small shape, and joins the steel sheet into a single sheet to increase productivity. In addition, it has the drawback that the joining quality is not stable at the welding start end and the end end, and this part must be cut off, resulting in poor product yield. However, the method described in the above-mentioned Japanese Patent Publication No. 5-25596 is not satisfactory in joining, and the emergence of an advantageous joining method is awaited.

[0005]

SUMMARY OF THE INVENTION A basic structure of a method for joining steel strips according to the present invention, which has been completed for the purpose of meeting the above-mentioned demands, is to form three different edges of steel strips 1, 2, and 3. In continuous welding, the steel strips 1 and 2 are passed between a welding roll and a plurality of holding rolls arranged at an angle to apply a force in the width direction to the steel strips 1 and 2 so that the steel strips 1 and 2 can be welded.
Laser welding is performed while a pressing force is applied to the edge of the edge of the steel strip. Then, the welded steel strips 1 and 2 and the steel strip 3 are
By passing between the welding roll and the plurality of holding rolls arranged at an angle, a force in the width direction is applied to the steel strip so that the pressing force acts on the edge end surfaces of the steel strips 1 and 2 and the steel strip 3. To perform laser welding. Further, in such a method, a flange roll is disposed upstream of a welding point to be laser-welded so as to provide a gap between the steel strips.
The invention according to the present invention.

That is, according to the present invention, steel sheets used for automobile parts are not made of one sheet of the same material, but steel sheets having different thicknesses, strengths or properties are used as steel strips before press forming. This is a method of joining steel strips to obtain a steel sheet having the required formability or strength required by an automobile part to be formed by welding, and then shearing a foreign steel sheet into a small shape. Instead of a method with poor productivity in which these ends are butt-joined, by continuously welding the ends of three different steel strips unwound from the coil, the productivity is good and It is an object of the present invention to provide a method of joining steel strips, which is extremely advantageous in that the joining quality is improved even when the shape accuracy of the end of the steel strip is poor. In addition, as an automobile part manufactured from the steel strip obtained by the present invention, a part close to a columnar shape such as a skeleton structure part of an automobile or a part that may be used by joining different materials such as a floor in parallel. The method of the present invention makes it possible to dramatically improve the productivity and yield of these parts.

[0007]

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention
This is a method for joining steel strips in which the edges of three steel strips 1, 2, and 3 having different sheet thicknesses and the like are continuously and advantageously welded. ,
2, a force is applied in the width direction of the steel strip so that a pressing force acts between the edges of the steel strip, and welding is performed. Then, the welded steel strips 1 and 2 and the steel strip 3 are formed in the same manner as described above. Welding is performed at different welding positions by using a pressing roll that is inclined in such a manner that a pressing force is applied between the edges, and the three steel strips 1,
The present invention is characterized in that welding can be easily performed in a few steps, and the joining can be performed with good joining quality as well as productivity.

Hereinafter, the present invention will be described in detail with reference to FIGS. In the present invention, the edges of three types of steel strips 1, 2, and 3 having different materials, plate thicknesses, and the like are continuously joined. First, the steel strips 1 and 2 are arranged side by side and the upper pressing rolls 4a and 5a are used. Then, it passes between the holding rolls 4a, 5a and the welding roll 7a having a larger diameter than that of the holding rolls 4a, 5a. At this time, the steel strips 1 and 2 are wound around the large-diameter welding roll 7a and pass therethrough, but the holding rolls 4a and 5a are welding rolls arranged so as to be orthogonal to the traveling direction of the steel strips 1 and 2. each angle theta ₁ with respect to the longitudinal direction of 7a, so as to be arranged is inclined by theta _2, the width direction of the force to the steel strip 1 is pressed against the welding roll 7a as added positively.

As described above, in the present invention, the pressing roll 4
The feature of the present invention is that the width of the steel strips 1 and 2 is positively applied to the steel strips 1 and 2 by inclining the strips a and 5a, and a surface pressure acts between the edges of the steel strips 1 and 2 to be welded. When the ends of the steel strips 1 and 2 are butt-welded and laser-welded, if a gap is generated between the steel strips 1 and 2 to be welded, poor quality such as undercut is likely to occur after welding. However, usually, when manufacturing the steel strip, in order to ensure the accuracy of the width of the steel strip and the shape quality of the end of the steel strip, slit the center of the steel strip,
It is finished by shearing of the end such as trimming the end, but since slight irregularities remain at the end of the steel strip, some gaps occur when these end faces are abutted,
When performing laser welding, a gap is generated near the upstream of the welded portion because a force that pushes the butted surface of the steel strip is applied due to the thermal contraction of the welded portion. Therefore, in the present invention, the press rolls 4a and 5a are inclined to apply a force in the width direction to the steel strips 1 and 2 to apply a butting force to the ends of the steel strips 1 and 2 to be welded, thereby forming a gap due to heat shrinkage. The gap between the ends of the steel strips 1 and 2 at the welding point is remarkably reduced by pressing and further applying elastic deformation or plastic deformation of the protrusions at the ends of the steel strip to significantly reduce the gap due to the unevenness. It is possible to secure stable welding quality.

At this time, in order to apply a force in the width direction of the steel strip,
Normally, a method of applying a force from the end of the steel strip such as a side guide roll on the non-welded side is generally considered. However, for a thin steel strip such as used for automobile parts, these methods have a large effect. If force is applied, buckling of the steel strip or roughening of the ends will occur, so a large force cannot be applied, and the gap between the ends of the steel strip to be welded cannot be sufficiently reduced. There was a problem. Therefore, in the present invention, the pressing roll 4 is used to apply a force in the width direction to the steel strips 1 and 2.
a, 5a is inclined and pressed.
By appropriately adjusting the pressing force and the inclination angle of the pressing rolls 4a, 5a, a sufficient pressing force can be applied to the automobile parts without causing buckling of the steel strips 1, 2 and roughening of the ends. It can be applied to thin steel strips.

In the present invention, a steel strip end positioning device is installed at one of the ends of the steel strips 1 and 2 where welding is not performed, and the holding rolls 4a and 5a are attached to the steel strips 1 and 2 respectively. Is inclined so that a pressing force acts in a direction in which the end positioning device is installed. For this purpose, the holding rolls 4a and 5a are also inclined in the same direction. That is, for the joining surface 10a of the steel strip 1 and the steel strip 2,
Generally, joining is performed by applying a pressing force from both sides toward the joining surface 10a.
In this case, the pressing rolls 4a and 5a are inclined by the angles θ ₁ and θ _{2 in the} same direction, respectively. To apply the pressing force from both sides toward the joining surface 10a, it is necessary to adjust the pressing force from both sides in a well-balanced manner so that the joining surface 10a does not always fluctuate to the welding position, but adjust the pressing force from both sides. it is difficult to, as in the present invention, with respect to the steel strip first end positioning apparatus side, end positioning device the ends of the end part positioning apparatus side of the steel strip 1 by pressing the pressing roll 4a tilted theta ₁ , And the position of the steel strip 1 in the width direction can be stabilized. Further, since the position in the width direction of the steel strip 2 to be pressed against the weld end of the steel strip 1 stable by pressing the pressing roll 5a inclined theta _2, the bonding surface 10a and the welding position is adjusted so as not to vary Is based on the finding that it is extremely easy. Moreover, welding to the pressing force between the strip ends can be easily controlled by adjusting the pressing force of the roll 5a and the inclination angle theta ₂ retainer furthermore welded steel strip 1 large-diameter Wrapping around the roll 7a allows the butt precision in the thickness direction of the steel strips 1 and 2 to be adjusted well. If not wrapped, a space between the steel strips 1 and 2 and the welding roll 7a is easily formed. This is because there is a high possibility that the butting accuracy of the strip 1 and the steel strip 2 in the thickness direction is not sufficient.

According to the present invention, various investigations are made so that the joint surface 10a to be welded is always at the welding position with respect to the position of the fixed laser emitting tube 9a for irradiating the laser beam 8a. This has led to the present invention, which is significantly different from the idea. That is, an idea is given that pressing force is applied to the steel strip from both sides to the joint surface 10a so that the position of the joint surface 10a does not fluctuate from the welding position. The idea is to apply a pressing force so that the steel strip moves to one side of 1 and 2. For example, as shown in FIG. 1, edge guides 11a, 11b, 1
1c, and their edge guides 11a, 11b, 11c
Press roll 4 inclined so that the steel strip 1 moves in the direction of
a is provided above the welding roll 7a. Pressing roll 4a
For example, the steel strip 1 is moved in the direction of the arrow while restraining the steel strip 1 by applying a pressing force to the welding roll 7a by a cylinder or the like. At this time, the holding roll 4a has an angle θ.
Since only ₁ inclined, the strip 1 is edge guide 11
a, 11b. In addition, steel strip 1
Roll 4a retainer as edge is not damaged so that can adjust the pressing force and the angle theta _1. Further, when the steel strip 1 is restrained by the edge guides 11a and 11b, the edge guides 11a and 11b are adjusted in the width direction of the steel strip 1 so that the position of the joint surface 10a to be welded of the steel strip 1 becomes the welding position. Is possible.

In this manner, the position of the steel strip 1 is adjusted in the width direction.
However, similarly, the steel strip 2 is angled θ._TwoOnly inclined
It is moved while being restrained by the pressing roll 5a, and
One, θ _TwoAnd the holding force of the holding roll 5a is adjusted appropriately.
As a result, the joining surface 10a of the steel strip 2 is
10a so that an appropriate pressing force is applied to the steel strips 1 and 2
Welding with the surface pressure of the edge surface of
In other words, the pinch method
The welding quality is improved,
Things. By doing so, the pressing force in one direction
The joint position of steel strips 1 and 2 can be adjusted accurately with only consideration
As well as applying pressure between the edges of steel strips 1 and 2 to melt them.
As a result, the welding quality is improved. this
Surface 10a of steel strips 1 and 2 was adjusted to the welding position as described above.
Later irradiates laser beam 8a from laser firing tube 9a
Then, the steel strips 1 and 2 are joined.

After welding the steel strip 1 and the steel strip 2 in this manner,
The welded steel strips 1 and 2 and the steel strip 3 are combined with a welding roll 7b,
By passing between the plurality of holding rolls 4b, 5b, and 6 arranged in an inclined manner, a force in the width direction is applied to the steel strip so that a pressing force acts on the edge end surfaces of the steel strips 1, 2 and the steel strip 3. Laser welding is performed during the process. That is, similarly to the welding of the steel strip 1 and the steel strip 2, the welded steel strips 1, 2
And presser rolls 4b and 5b inclined by angles θ ₃ and θ ₄ are provided on the upper part of the welding roll 7b, and the presser rolls 4b and 5b are used to weld the steel strip 3.
b, and press the steel strips 1 and 2 to the edge guide 11.
b, 11c. Similarly, by moving the steel strip 3 in a state of being restrained by the press roll 6 inclined by the angle θ ₅ and adjusting the θ ₅ and the press force of the press roll 6 appropriately, the joining surface 10b of the steel strip 3 is formed. Is to apply an appropriate pressing force to the joining surface 10b of the steel strips 1 and 2 to apply a surface pressure to the edge surfaces of the steel strips 1 and 2 and the steel strip 3, and to weld in a state where the gap is crushed, The welding quality is improved, which is extremely advantageous. As shown in FIGS. 3 and 4, four pressing rolls 4, 5, and 6 may be used for each of the steel strips 1, 2, and 3. Various arrangements are possible, but there is no particular preference.

[0015] Further, as shown in FIG.
The groove 12a is provided at a position corresponding to the welding position, thereby preventing damage to the welding roll 7a due to the thermal influence during welding. Although FIG. 5 shows the joining of the steel strips 1, 2, and 3 having different thicknesses, the welding rolls 7a
The diameter of the steel strip 1 is the same over the entire length.
2 is welded in accordance with the lower surfaces of the steel strips 1 and 2. In FIG. 6, the upper surfaces of the steel strips 1 and 2 are welded together, and in FIG. 7, the thin steel strip 2 is welded to the center of the thickness of the thick steel strip 1. Can be easily achieved by using a welding roll 7a having a different diameter on the left and right across the groove 12a of the welding roll 7. The right and left diameters of the welding roll 7a may be made variable by making the welding roll 7a freely expandable and contractable, and the means thereof is not particularly limited. Although the groove 12a has been described using the welding roll 7a as an example with reference to FIGS. 5 to 7, the welding roll 7b is also provided with a groove 12b (not shown) at a position corresponding to the welding position. Is the same as that of the welding roll 7a.

Further, in the present invention, as shown in FIG. 8, a flange roll 14a is arranged on the upstream side of the welding point 13a to provide a gap between the steel strips 1 and 2. In addition, the present invention passes the steel strips 1 and 2 on the same plane,
In this case, the joining surfaces 10a of the steel strips 1 and 2 may be rubbed or the steel strip 1 and the steel strip 2 may overlap with each other. It is more preferable to provide the flange roll 14a between them.
Note that the flange roll 14b is also provided on the upstream side of the welding point 13b.
Is also more preferable.

The pressing roll 4, used in the present invention,
5 and 6, but is intended to respective angle theta ₁ through? ₅ inclination angle theta ₁ through? ₅ are both 2 ° to 25 ° is preferred,
The pressing force of the pressing rolls 4, 5, and 6 is 350N or more.
20000N is preferred. The reason is that the angles θ _{1 to} θ ₅
If the angle is less than 2 ° or the holding force is less than 350N, the pressing force in the width direction of the steel strips 1, 2, and 3 is insufficient, and the welding quality is not preferable, and the angle θ _{1 to} θ ₅ exceeds 25 ° or the holding force is higher. If it exceeds 20,000 N, the pressing force becomes too large, and buckling of the steel strips 1, 2, and 3 may occur.
However, the above-described ranges of the angle and the pressing force are merely preferred ranges, and are not limited to these ranges unless buckling occurs. Also, the three different steel strips of the present invention are different in the material and thickness of adjacent steel strips, and also include those in which the steel strips at both ends are the same and the central steel strip is different. Is what it is.

[0018]

Example 1 A steel strip 1 having a thickness of 0.7 mm and a width of 250 mm having the chemical components shown in Table 1 manufactured according to a conventional method and a thickness of 1.4.
mm, width 690 mm steel strip 2, thickness 0.7 mm, width 2
A steel strip 3 of 50 mm is prepared, and the steel strip 1 and the steel strip 2 are joined at a speed of 1.7 m / min with a 2 kW laser welding machine. Then, the steel strip 3 is joined to the welded steel strips 1 and 2. Joining was performed at a speed of 1.7 m / min with a 2 kW laser welding machine. Hereinafter, the components of the steel strip are shown in Table 1, and the joining conditions and welding results are shown in Table 2,
3 is shown.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3] As is clear from the above table, according to the present invention, no buckling occurs, no undercut occurs, and extremely good welding quality is obtained.

[0022]

Embodiment 2 Each of the steel strip 1, steel strip 2 and steel strip 3 shown in Embodiment 1 is formed into an automobile part (center pillar) by 10 parts.
It was cut to 00 mm. In this case, the present invention provides steel strips 1, 2,
3 was cut after joining, and in the comparative example, steel strips 1, 2, and 3 were cut, and then the steel sheets were joined. Table 4 shows the time required at that time.
Shown in

[0023]

[Table 4] As shown in Table 4, according to the present invention, it can be seen that productivity is remarkably improved as compared with the cut plate joining method shown in the comparative example.

[0024]

As is apparent from the above description, according to the present invention, when manufacturing automobile parts and the like by the tailored blank method, it is possible to join steel strips having good welding quality and high productivity. The effect is extremely large.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view of the method of the present invention.

FIG. 2 is an explanatory side view of the method of the present invention shown in FIG.

FIG. 3 is an explanatory plan view of the method of the present invention in which the number of press rolls is increased.

FIG. 4 is an explanatory side view of the method of the present invention shown in FIG. 3;

FIG. 5 is an enlarged explanatory view showing the vicinity of welding in the method of the present invention.

FIG. 6 is an enlarged explanatory view showing the vicinity of welding in the method of the present invention.

FIG. 7 is an enlarged explanatory view showing the vicinity of welding in the method of the present invention.

FIG. 8 is an explanatory view of a state in which a flange roll is provided upstream of a welding point in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel strip 1 2 Steel strip 2 3 Steel strip 3 4 Pressing roll 5 Pressing roll 6 Pressing roll 7 Welding roll 8 Laser beam 9 Laser firing tube 10 Joining surface 11 Edge guide 12 Groove 13 Weld point 14 Flange roll

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuru Okamoto 5-3 Tokaicho, Tokai City, Aichi Prefecture Inside Nippon Steel Corporation Nagoya Works (72) Inventor Yasuo Sasaki 5-3 Tokaicho, Tokai City, Aichi Prefecture F-term in Nippon Steel Corporation Nagoya Works (reference) 4E068 BE00 BE02 CA14 DA14 DB01

Claims (2)

[Claims] When continuously welding the edges of three different steel strips (1, 2 and 3), the steel strips (1 and 2) are placed between a welding roll and a plurality of holding rolls arranged at an angle. Pass through the steel strip to apply a force in the width direction.
Laser welding is performed while a pressing force is applied to the edge of the edge of the steel strip. Then, the welded steel strips 1 and 2 and the steel strip 3 are
By passing between the welding roll and the plurality of holding rolls arranged at an angle, a force in the width direction is applied to the steel strip so that the pressing force acts on the edge end surfaces of the steel strips 1 and 2 and the steel strip 3. A method for joining steel strips, comprising laser welding while forming. 2. The method for joining steel strips according to claim 1, wherein a flange roll is arranged upstream of a welding point for laser welding to provide a gap between the steel strips.