JP2011083781A - Method for manufacturing h-section steel by laser welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a H-section steel excellent in shape accuracy by one pass laser welding with high productivity when manufacturing a welded H-section steel by welding T-shaped welding joints at two places. <P>SOLUTION: When the welded H-section steel is manufactured by laser welding the T-shaped welding joints at the two places where a flange material is pressed to both ends of a web material, two laser heads are arranged at the one side of the web material. The T-shaped joints at the two places positioned at the vertical surface of the web material and the flange material for forming the welded H-section steel are made to be mutual fulcrums. One laser head is tilted at an upperstream side in a welding direction and the other laser head is tilted at a downstream side in the welding direction, the two laser heads are mutually tilted and positioned at the web material side to the flange material surface, and cross portions at the two places are simultaneously laser welded on the same line L by the two laser heads. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a welded H-section steel in which a web material and a flange material are welded together by laser welding using a laser beam as a heat source.

H-section steel used for beams and the like constituting a building frame has been manufactured by hot-rolling into a predetermined cross-sectional shape, followed by post-plating, post-coating, etc. as necessary.
However, in response to the recent increase in durability and cost of housing, surface-treated steel sheets, especially Zn-based plated steel sheets containing Zn in the plated metal, are used continuously for the web material and flange material forming H-section steel. A welded H-section steel manufactured by a method of joining by high frequency welding is used.

  The welded H-section steel is usually manufactured by positioning a base plate such as a plated steel strip that is continuously fed with upper and lower, left and right rolls and performing high-frequency welding while applying pressure. However, when the high frequency welding method is adopted, the vicinity of the T-joint portion of the heated flange material and the web material and the contact portion between the material and the electrode are also heated, so that the portion that contacts the electrode as well as the welded portion In this case, the plated layer of the material is damaged. Therefore, it is necessary to apply the repair paint over a wide range in order to ensure the corrosion resistance of the damaged part.

In addition to the above-described problems, the high-frequency welding has a problem that the electrode itself is severely worn and the electrode needs to be replaced in a short time. The replacement of the electrodes in a short time includes a problem that the welding cost increases and the production efficiency decreases. Moreover, since it is necessary to apply a large welding current in high-frequency welding, there is a problem that equipment investment is increased because the welding machine is large and very expensive.
Furthermore, size restrictions are added to the welded shape steel. That is, in high-frequency welding, it is necessary to bring the electrode into contact with the material surface. However, since the electrode holder easily comes into contact with the flange portion of the H-shaped steel, it is difficult to weld a small product. A size of about W80 mm × H80 mm is the limit, and it is difficult to manufacture an H-shaped steel having a size smaller than that by high-frequency welding.

On the other hand, it has also been proposed to employ a laser welding method in which a T-shaped joint portion between a flange material and a web material is irradiated with laser light.
For example, in patent document 1, as shown to Fig.1 (a), the laser welding of 4 times is performed one place. Moreover, in patent document 2, as shown in FIG.1 (b), the process of carrying out laser welding of two places simultaneously is performed twice. The methods proposed in each of the above patent documents require a large number of welding steps, and thus the productivity is low.

Accordingly, the present inventors have performed fillet welding by irradiating a laser beam from only one side to a T-shaped joint portion in which the end portion of the web material is pressed vertically against the flange material, as shown in FIG. It has been proposed to manufacture a welded H-section steel by going back (see Patent Documents 3 and 4).
Even this method requires two steps, and the productivity is not always good.

Japanese Patent Laid-Open No. 11-123575 JP 2005-21912 A JP 2007-307591 A Japanese Patent Application No. 2007-293921

According to the manufacturing methods proposed in Patent Documents 1 to 4, productivity is low due to the large number of processes.
In order to increase productivity, it is assumed that four laser heads are used and four locations are welded at once. However, the installation of the four laser heads not only requires a large capital investment, but when a small-sized H-shaped steel is to be manufactured, the laser heads interfere with each other as shown in FIG. As a result, a problem is likely to occur in focusing the laser beam.

In addition, the installation of two laser heads using the method of irradiating laser light from only one side as proposed in Patent Documents 3 and 4 also involves interference of the laser heads.
In order to eliminate the interference of the laser head, as shown in FIGS. 4 and 5, it is assumed that the welding is divided into two parts, but the four weldings are performed in two parts. There is a possibility that the welding position shifts due to deformation. Even if the welding position does not shift, thermal deformation remains and the product shape may be inferior.

  The present invention has been devised to solve such a problem. When a welded H-section steel is manufactured by forming two T-shaped joints by laser welding, the shape accuracy is obtained in one pass. The purpose is to produce an H-shaped steel with excellent productivity.

In order to achieve the object, the method for producing H-shaped steel by laser welding according to the present invention laser welds two T-shaped joint portions in which a flange material is pressed against both ends of a web material to weld H-shaped steel. When two laser heads are arranged on one side of the web material, the web material forming the welded H-shaped steel and the two T-shaped joints located on the vertical surfaces of the flange material are used as mutual fulcrums. Two laser heads in which one laser head is inclined to the upstream side in the welding direction, the other laser head is inclined to the downstream side in the welding direction, and is further inclined to the web material side with respect to the flange material surface. The two T-joint portions are laser welded simultaneously.
Under the present circumstances, it is preferable to irradiate a laser beam to a T-shaped joint part, pressing a flange material to the both ends of a web material.

In the method of the present invention, two laser heads that irradiate two T-shaped joint portions formed by vertically pressing the end portions of the web material against the flange material are welded to one side of the web material and welded. Using two T-shaped joints located on the vertical surfaces of the web material and the flange material forming the H-shaped steel as fulcrums, one laser head is inclined upstream in the welding direction, and the other laser head is welded. Inclined to the downstream side in the direction and further inclined to the web material side with respect to the flange material surface. For this reason, the two laser heads do not interfere with each other.
Since the two laser heads do not interfere with each other, it is possible to perform welding at two locations on the same line by one-pass welding on one side from the same direction, and a welded H-section steel with excellent shape accuracy can be easily obtained. Can be manufactured.
Therefore, according to the present invention, it is possible to manufacture a welded H-section steel having high shape accuracy and high corrosion resistance at a low cost with only minimal weld repair even if it is an H-section steel made of a plated steel sheet. It becomes possible.

The figure explaining the laser welding method proposed by patent documents 1, 2 The figure explaining the laser welding method proposed by patent documents 3 and 4 The figure explaining the aspect which a several laser head interferes The figure explaining the form which divides and arranges a plurality of laser heads The figure explaining the other form which divides and arranges a plurality of laser heads The figure explaining the laser head division arrangement form when adopting the method proposed by patent documents 3 and 4 Diagram explaining thermal deformation after welding The figure explaining an example of shape correction after welding The figure explaining the laser head arrangement form in the method of the present invention The figure explaining the arrangement | positioning procedure of the laser head in this invention method

The inventors of the present invention produce a welded H-shaped steel with high productivity and high shape accuracy when manufacturing an H-shaped steel with two T-shaped welded joints using a steel plate as a raw material. We have been studying the means to do this.
As described above, it is assumed that four laser heads are used and four locations are welded at one time. However, the installation of the four laser heads requires not only a large capital investment but also a small size. When trying to manufacture the H-shaped steel, the laser head interferes and the laser beam focusing is liable to occur.

In order to eliminate the interference of the laser head, as shown in FIGS. 4 and 5, it is assumed that the welding is divided into two parts, but the welding is performed at two places, that is, the same, that is, the same. Since they are not performed simultaneously on the wire, the welding position may shift due to thermal deformation. Even if the welding position does not shift, thermal deformation remains and the product shape may be inferior.
Further, as seen in FIG. 5, when welding at two locations by one-pass welding on one side, welding is performed from opposite directions, which is not preferable for safety as described later.

Also, in order to utilize the method of irradiating laser light from only one side as proposed in Patent Documents 3 and 4, two laser heads are installed at positions sandwiching the web material in order to prevent interference of the laser heads. It is also assumed that two locations are laser welded simultaneously (see FIG. 6).
However, when welding in the left-right direction as shown in FIG. 6 (a), one side faces upward, and as shown in FIG. 6 (b), one side also faces upward, so that spatter is scattered or laser light is emitted. Considering the case of misfiring, it is not preferable for safety.
Furthermore, the welded portion of the T-shaped joint in the method of irradiating laser light from only one side is strictly an asymmetrical welded portion due to melting from one side, and the amount of deformation due to welding heat is also different from that on the front bead side. Since the bead side is different as shown in FIG. 7, when the two laser heads are installed at positions sandwiching the web material and welded, the shape becomes asymmetrical (see FIG. 7B).

  When correcting the shape defect due to thermal deformation of the flange after welding, as an example, the shape can be corrected by inserting a tapered roll between the flanges as shown in FIG. If the deformation is symmetrical, the upper and lower rolls can be placed on the same line, and the shape can be easily corrected by controlling the push amount of the upper and lower rolls, and a welded H-section steel with excellent shape accuracy can be easily obtained. (See FIG. 8A). However, when the deformation is asymmetrical, the correction roll cannot be arranged on the same line, so that it becomes easy to cause bending or twisting, and further, the shape correction becomes difficult because the left and right deformation amounts are different ( (Refer FIG.8 (b)).

Therefore, the inventors of the present invention inclined the two laser heads on the opposite sides with respect to the surfaces perpendicular to the flange material and the web material so as not to interfere with each other, that is, one of them is in the traveling direction of the welding line. The other side is inclined and arranged behind the welding line, and the two T-shaped joint portions are welded simultaneously (on the same line perpendicular to the line direction). The tilting angle is preferably the same angle on the opposite side with respect to the vertical plane.
Furthermore, in order to weld two T-shaped joints on the same line L perpendicular to the line direction, the direction of each laser head is perpendicular to the flange material and web material, respectively. Two laser heads are arranged so as to face the crossing portions of the materials. See FIG.
In this way, by arranging the two laser heads in an inclined manner, the laser heads do not interfere with each other, and since two locations can be welded simultaneously on the same line, the occurrence of harmful effects due to thermal deformation is suppressed. be able to.

Next, a preferred procedure for arranging the two laser heads in an inclined manner will be described.
First, as shown in FIG. 10A, assuming a surface F perpendicular to the flange material and the web material, two laser heads A and B are sandwiched between the surface F on the upstream side and the downstream side of the surface F. Deploy. Next, the two laser heads A and B are respectively inclined at an angle of 10 to 25 ° so that the plane F perpendicular to the longitudinal direction of the flange material and the web material faces the portion intersecting the web material (FIG. 10). (See (b)). The inclination angles at this time are not necessarily the same, but are preferably equal to the plane F perpendicular to the flange material and the web material. Thereafter, the two laser heads A and B are inclined in directions opposite to each other at an angle of about 10 ° with respect to the flange, and then the surface F and the flange material perpendicular to the flange material and the web material in opposite directions, respectively. Is moved parallel to the crossing point (see FIG. 10C).

In tilting the two laser heads A and B forward and backward in the direction of travel of the welding line, the forward and backward tilt angles in the forward direction may not be the same angle with respect to the vertical. For example, one may be vertical and the other may be inclined either before or after the welding line traveling direction. In any case, it is preferable that the inclination angle is set to the minimum angle at which the two laser heads do not interfere with each other within about 25 degrees before and after the traveling direction.
Then, laser welding may be started after the two laser heads A and B are directed to the portion where the flange material and the surface F perpendicular to the web material intersect with the flange material.

  By the way, a high-power laser is used in the laser welding method. For this reason, although the metal to be joined is melted, it is partially evaporated and scattered, and the metal to be welded is slightly reduced. Also, the welded metals are in contact with each other, but there is a slight gap when the end face is not chamfered, and there is a shortage of joint metal due to the reduction of the welded metal and the effect of the gap between the welded metals. To do. In addition to these phenomena, a shield gas is sprayed at the welding point, so that a gas pressure is applied to the molten pool, and a depression may be formed in the weld joint due to the influence of gravity. As a result, a predetermined bonding strength may not be obtained.

Therefore, in the present invention, it is preferable to melt the web material itself by pressing the web material to compensate for the shortage of the joining metal in the joint portion and increase the joining strength.
Although there is no restriction | limiting in the pressing method and pressing amount of a web material, It is preferable to press a flange material to the edge part of a web material with a squeeze roll. As the pressing amount, it is preferable to press the flange material so as to reduce the distance between the flange members by about 0.3 to 0.5 mm.

As described above, with the welding method using laser light as a heat source, a deep molten metal region can be formed with a narrow cross-sectional area. Therefore, the laser welding method is suitable for manufacturing a welded structure made of a plated steel plate, particularly a Zn-based plated steel plate, and further a steel plate subjected to Zn-Al-based or Zn-Al-Mg-based plating.
For this reason, the manufacturing method of H-section steel by laser welding of the present invention is used for manufacturing H-section steel made of Zn-based plated steel sheets, particularly steel sheets plated with Zn-Al-based or Zn-Al-Mg-based materials. Preferably used.

Example 1;
A hot-dip galvanized steel sheet in which a Zn-6% Al-3% Mg alloy plating layer was applied to a steel sheet having a thickness of 2.3 mm and a tensile strength of 400 N / mm ^{2 at} an adhesion amount of 90 g / m ² per side was used as a material. . A material cut to a plate width of 80 mm is used as a flange material, a material cut to a plate width of 75.4 mm obtained by dividing the thickness of two flanges from the product height is used as a web material, the flange material is vertical, the web material is horizontal, It fixed with a vise etc. so that a cross-sectional shape might become H shape, and produced 80 mm x 80 mm welded H-section steel. The welding method is a method in which two T-shaped joints formed by pressing a flange material perpendicularly to the end of a web material are simultaneously irradiated with laser light, and the two laser heads are web materials that form an H shape. And two T-shaped joints located on the vertical surface of the flange material, with one laser head tilted 15 degrees in the line traveling direction and the other laser head tilted 15 degrees rearward of the welding line In addition, the flange members are arranged so as to be inclined by 10 degrees toward the web side with respect to the vertically arranged flange material, and the direction of each laser head is arranged so as to face the portion where the flange material and the web material intersect, Two fillet welds were performed simultaneously across the entire width direction of the material. Laser power during welding was 4.0 kW, welding speed was 4.0 m / min, and shielding gas was supplied at 20 liters / min as argon.

Example 2;
In Example 1, since a loading material such as a wire is not used, it is assumed that a recess is formed in the welded joint. Therefore, as a method to compensate for the lack of weld metal in the welded joint, the vicinity of the welding point is pressed by a roll or the like by about 5 kN, and the irradiation position of the laser beam is about 3 to 6 mm from the contact point of the roll and the flange to the line entry side. When the position is irradiated, the joint portion passes through the roll contact point that is most pressed in the molten state, so that the pressing by the roll works effectively. At this time, since the height of the H-shaped steel is reduced by about 0.3 to 0.5 mm by being pressed by the roll, the web material has two flange thicknesses from a value obtained by adding about 0.5 mm to the product dimensions in advance. It is necessary to set to the board width divided. Other welding methods and welding conditions are the same as those in the first embodiment.

  And when the cross section of the H-section steel manufactured in Examples 1 and 2 was visually observed, in the H-section steel manufactured in Example 1, a very slight depression was observed at the intersection of the flange material and the web material. . On the other hand, in the H-shaped steel produced in Example 2, a weld bead was formed so as to protrude outside the intersection of the flange material and the web material, and no dent was observed at all.

Claims (2)

  When manufacturing a welded H-shaped steel by laser welding the two T-shaped joints with the flange material pressed against both ends of the web material, two laser heads are arranged on one side of the web material, and the welding is performed. Using two T-shaped joints located on the vertical surfaces of the web material and the flange material forming the H-shaped steel as fulcrums, one laser head is inclined upstream in the welding direction, and the other laser head is welded. Laser welding, wherein the two T-joints are simultaneously laser welded by two laser heads which are inclined to the downstream side in the direction and further inclined to the web material side with respect to the surface of the flange material. Manufacturing method of H-section steel.   The manufacturing method of the H-section steel by laser welding according to claim 1, wherein the T-joint portion is irradiated with laser light while pressing the flange material against both ends of the web material.

Images