JP6741358B2 - Laser welding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laser welding method that enables reliable welding when a member to be welded is laser-welded to a plate material such as a decorative material without impairing the design.

In elevators or escalators, design is important for the parts that can be seen by human eyes. Therefore, the decorative material used for the wall or the operation panel cannot be distorted or dented. On the other hand, it is necessary to join a stat bolt and a bracket to the back side of the decorative material, and various joining techniques are used.

As a concrete joining method, there is a conventional technique using resistance welding. However, when resistance welding is used, distortion occurs on the design surface due to welding heat. That is, in the joining using resistance welding, the energy density is lower than that in laser welding described later. Therefore, the melting amount becomes excessively large, and as a result, the strain becomes large and the designability is impaired. Therefore, when resistance welding is used, it is necessary to correct the design surface after welding.

Therefore, in order to reduce the strain, it is conceivable to adopt laser welding having a high energy density, and there are various conventional techniques (for example, refer to Patent Documents 1 to 3). Patent Document 1 discloses a method of making distortion inconspicuous by welding in a zigzag manner by laser welding.

Further, Patent Document 2 discloses a laser output control method for improving welding quality by gradually increasing the laser output at the start of welding and gradually decreasing the laser output at the end of welding during butt welding. Has been done.

Furthermore, Patent Document 3 discloses a laser output control method for improving welding quality by gradually increasing the laser output at the start of welding and gradually decreasing the laser output at the end of welding during lap welding. It is disclosed.

JP, 2007-253179, A JP-A-8-257775 JP, 2005-197548, A

However, the related art has the following problems.
When using laser welding according to Patent Document 1, if a weldable area is sufficiently large, a considerable number of welds may be performed in order to maintain the welding strength. However, it is not possible to secure the number of welds in a place where a weldable area is small, such as a stat bolt, and it is not possible to maintain sufficient weld strength.

Further, in the laser welding according to Patent Document 2, particularly when welding a member having a short welding length, it is conceivable that the welding ends before the original welding output is reached. Therefore, there is a problem that the laser welding does not sufficiently melt and the standard joining strength is not reached.

Further, the laser welding according to Patent Document 3 is a patent for welding on the upper member. Then, in the laser welding according to Patent Document 3, as in Patent Document 2, particularly when welding a member having a short welding length, it is conceivable that the welding ends before the original welding output is reached. Therefore, there is a problem that the laser welding does not sufficiently melt and the standard joining strength is not reached.

That is, since the conventional laser welding has a high energy density, it is possible to reduce the strain, and it is possible to make it difficult to visually check the strain at the central portion of the welding. However, since the welding start end portion and the welding end portion have a large difference from the surroundings, visible distortion is likely to occur.

Then, as a countermeasure against this, it is possible to make the energy invisible by gradually increasing the energy by using the up-slope control/down-slope control. However, when welding a member having a small weldable area such as a stat bolt, there is a problem that there is no weldable place in the middle of the upslope, and the strength cannot be maintained.

Further, in the case of using a decorative material having a constraint that the design cannot be modified, the material to be welded is bonded to the decorative material by using an adhesive material or a double-sided tape. Specifically, the technique of applying an adhesive to a decorative material and pressing/holding the material to be welded with this adhesive and joining it, or the technique of pasting the decorative material and the material to be welded with a double-sided tape has been conventionally used. Has been adopted from.

However, when an adhesive is used, there is a problem that the auxiliary material cost of the adhesive is expensive, and further, it takes time to cure the adhesive.

Further, even when the double-sided tape is used, there is a problem that the auxiliary material cost of the double-sided tape is expensive, and further, there is a problem that the adhesive strength is weak.

Note that instead of using an adhesive or a double-sided tape, a method of increasing the plate thickness of the design material to the extent that no distortion is generated and joining it by resistance welding or the like is also adopted. However, in this case, there is a problem that the material cost increases because the plate thickness is increased although it is not necessary in terms of strength.

The present invention is made in order to solve the problems as described above, and when joining a material to be welded having a small weldable area such as a stat bolt and a plate material such as a decorative material, the designability is improved. An object of the present invention is to obtain a laser welding method that enables laser welding without damaging the properties.

The laser welding method according to the present invention is a laser welding method of fixing a member to be welded to a plate material by laser welding, a member temporary placing step of temporarily placing the member to be welded on the plate material, and the member to be welded to the plate material. When performing laser welding, the laser starts along the welding path starting from the welding start position on the plate material, passing through one end of the welded member and the other end of the welded member, and ending at the welding end position on the plate material. In the welding process, the laser output is gradually increased from the initial laser output at the welding start position in the welding path from the welding start position to one end of the member to be welded. In the welding start process of performing welding by up-slope control to raise the preset laser output at one end of the welded member and the welding path from one end of the welded member to the other end of the welded member, In the main welding step of performing welding while maintaining the laser output at the main laser output, and in the welding path from the other end of the member to be welded to the welding end position, the laser output is set at the other end of the member to be welded. A welding end step is performed in which welding is carried out by down-slope control in which the laser output is gradually lowered to the initial laser output at the welding end position.

According to the present invention, in the welding path passing through the one end and the other end of the member to be welded, upslope control of the laser output in the welding path from the welding start position on the plate to the one end of the member to be welded, The laser output is maintained at the main laser output in the welding path from one end to the other end of the welded member, and the laser output is reduced in the welding path from the other end of the welded member to the welding end position on the plate material. Welding method with slope control is used. As a result, when joining a material to be welded having a small weldable area such as a stat bolt and a plate material such as a decorative material, it is possible to obtain a laser welding method that enables laser welding without impairing the design. it can.

It is a perspective view for explaining the laser welding method of the decorative material concerning Embodiment 1 of the present invention. It is the figure which showed the relationship between the welding position and the laser output at the time of applying the laser welding method of the decorative material which concerns on Embodiment 1 of this invention. It is a perspective view for explaining the 1st time of welding by the laser welding method of the decorative material concerning Embodiment 2 of the present invention. It is a perspective view for demonstrating the 2nd welding by the laser welding method of the decorative material which concerns on Embodiment 2 of this invention. It is the figure which showed the relationship between the welding position and the laser output at the time of applying the laser welding method of the decorative material which concerns on Embodiment 2 of this invention.

Preferred embodiments of the laser welding method of the present invention will be described below with reference to the drawings. In the following first and second embodiments, a case where the plate material to be welded is a decorative material and the member to be welded is a stat bolt will be described as a specific example, but the application target of the present invention is not limited to this. Not something.

Embodiment 1.
In the first embodiment, an embodiment in which a small component such as a stat bolt is laser-bonded to a decorative material will be described. FIG. 1 is a perspective view for explaining a laser welding method for a decorative material according to Embodiment 1 of the present invention. More specifically, FIG. 1 is a perspective view showing a state in which a stat bolt 2 fixed on a decorative material 1 by a jig is welded while moving a laser welding head.

FIG. 2 is a diagram showing the relationship between the welding position and the laser output when the laser welding method for a decorative material according to the first embodiment of the present invention is applied. The laser welding method for the decorative material according to the first embodiment will be described in detail with reference to FIGS. 1 and 2.

First, the laser welding head 3 moves to the welding start position P1 on the welding line 4. The distance L1 between the welding start position P1 and the stat bolt 2 is preferably 10 mm or more. If the distance L1 is less than 10 mm, there is a possibility that the laser welding head 3 having started moving from the welding start position P1 will not reach the laser output LO1 at the time when the laser welding head 3 reaches the stat bolt 2. It may not be possible to secure enough.

Next, laser irradiation is started, but first, welding is started with an initial laser output LO2 which is an output suppressed to be lower than in the main welding. If the initial laser output LO2 is too large, it will cause distortion on the design surface. Therefore, it is necessary to apply LO2 of 50 W or less.

Next, the laser welding head 3 starts moving from the welding start position P1 along the laser welding head moving direction DIR. At that time, as shown in FIG. 2, the laser output of the laser welding head 3 is increased proportionally until reaching the main welding start position P2, and finally reaches the main laser output LO1 at the main welding start position P2. Upslope control is performed so that it reaches.

At this time, the laser output increase rate 101 is preferably 15 W/mm or less. If the laser output is increased at 15 W/mm or more, a sharp increase in the amount of welding heat will occur. As a result, welded navy blue is abruptly generated on the back surface, causing visible distortion, which may result in poor quality.

It should be noted that even if the thickness of the decorative material 1 changes, the increase 101 in the laser output is still 15 W/mm or less. However, the laser output LO1 needs to be larger when the plate thickness is thick and smaller when the plate thickness is thin.

After reaching the main welding start position P2, the laser welding head 3 carries out welding at the main laser output LO1 up to the main welding end position P3.

Next, after reaching the main welding end position P3, the laser output of the laser welding head 3 is gradually lowered, contrary to the time of starting the welding, and finally reaches the initial laser output LO2 at the welding end position P4. Then, the down slope control is executed and the welding is completed.

At this time, the laser output decrease rate 102 needs to be 15 W/mm or less, like the laser output increase degree 101. Further, the distance L2 between the welding end position P4 and the stat bolt 2 also needs to be 10 mm or more, like the distance L1.

The plate thickness of the flange 21 of the stat bolt is preferably 1.0 mm or less. This is because if the plate thickness of the flange 21 exceeds 1.0 mm, the heat capacity greatly changes at the point where the laser enters the flange 21 of the statbolt 2 and visible distortion occurs.

According to the first embodiment, the strain generated by the welding heat of the laser gradually changes. Therefore, the generated strain becomes invisible and the stat bolt 2 can be welded to the decorative material 1 without impairing the design.

Further, when starting the welding in the flange 21 of the stat bolt 2, it is necessary to start/end the welding about 1 mm inside the outer circumference of the flange 21 in consideration of the diameter variation of the flange 21. Therefore, the welding length is inevitably reduced.

On the other hand, when applying the welding method described in the first embodiment, it is not necessary to consider the diameter variation of the flange 21 of the stat bolt 2. Therefore, the entire length of the flange 21 can be welded, and the welding strength can be improved.

Embodiment 2.
In the second embodiment, the first welding is performed in the flange 21 to measure the magnitude of strain, and the value of the main laser output is set to an appropriate value from the measurement result, and then the second welding is performed. A case where the welding procedure described in the first embodiment is executed will be described.

FIG. 3 is a perspective view for explaining the first welding by the laser welding method for the decorative material according to the second embodiment of the present invention. Further, FIG. 4 is a perspective view for explaining the second welding by the laser welding method for the decorative material according to the second embodiment of the present invention.

Further, FIG. 5 is a diagram showing a relationship between a welding position and a laser output when the laser welding method for a decorative material according to the second embodiment of the present invention is applied. The laser welding method for the decorative material according to the second embodiment will be described in detail with reference to FIGS. 3 to 5.

First, as shown in FIG. 3, the laser welding head 3 performs the first laser welding between the first welding start position P11 and the first welding end position P12 set in the flange 21 of the stat bolt 2. Perform welding.

This first laser welding is welding for maintaining the bonding strength, and it is necessary to secure a sufficient laser output. Therefore, as shown in FIG. 5, in the first welding, the laser welding head 3 uses the main laser output LO3, which is larger than that in the second welding described later, to finish the first welding from the first welding start position P11. Laser welding between positions P12 is performed.

Next, the welding operator observes the design surface of the decorative material 1 after performing the first welding, and measures the magnitude of strain. Then, based on the measurement result of the strain, as shown in FIG. 4, the second laser welding is performed in the same procedure as in the first embodiment.

That is, in the second welding, as in the first embodiment, the up-slope control and the down-slope control are performed, so that the welding start position P21, the main welding start position P22, the main welding end position P23, and the welding are performed. Welding on the welding line 4 defined by the end position P24 is executed. Here, the second welding start position P21 and the second welding end position P24 need to have a sufficient distance between them and the flange 21 of the stat bolt 2 as in the first embodiment.

Further, the main laser output LO4 in the second welding can be made more inconspicuous by changing it to an appropriate value according to the way the strain is measured after the first welding.

That is, when the strain is larger than the value predicted from the laser output LO3 as a result of the measurement after the first welding, the main laser output LO4 is larger than the value used in the first embodiment. Use the output value. On the contrary, when the distortion is smaller than the value predicted from the laser output LO3, an output smaller than the value used in the first embodiment is adopted as the main laser output LO4.

Further, by selecting the second welding condition so that the strain gradually changes, the first welding mark can be corrected. For this reason, after passing through the second welding, the welding marks of the first welding also become invisible distortion, and welding can be performed without impairing the design.

Further, according to the second embodiment, even when the strain generated at the start and end of the first welding changes due to the variation in the plate thickness of the flange 21 of the stat bolt 2 and the variation in the laser output, the measurement results are also obtained. This can be dealt with by changing the second main laser output according to.

In the second embodiment, the case where the main welding is performed for the first time and the second correction welding is performed based on the measurement result has been described. However, contrary to this procedure, the same effect can be obtained by performing the correction welding for the first time and the main welding for the second time.

As described above, according to the present invention, the following procedure is adopted when joining a welded member having a small weldable area such as a stat bolt and a decorative material.
・Start up welding by putting up-slope control from the outside of the stat bolt flange.
-Pass the stat bolt where you want to weld it under the main welding conditions.
-Welding ends while controlling the down slope outside the flange of the stat bolt.

By adopting such welding method, laser welding is performed on a welded member having a small weldable area such as a stat bolt with respect to a decorative material, including a welding start portion/end portion, without impairing the design. It becomes possible.

Further, by performing the welding in two stages of the main welding and the correction welding, it is possible to compensate for the variation in the plate thickness and the variation in the laser output, and it is possible to perform the laser welding without impairing the design.

Then, by adopting the laser welding method according to the present invention, the post-process work such as the modification of the design surface after the welding work is eliminated, and the processing cost can be reduced. Further, it is not necessary to use an adhesive or a double-sided tape, and proper laser welding can be realized without increasing the material cost.

In the first and second embodiments described above, the case where the laser welding head 3 is moved along the welding path after the stat bolt 2 that is the member to be welded is temporarily placed on the decorative material 1 that is a plate material explained. However, the present invention is not limited to such a configuration, and instead of moving the laser welding head 3, the decorative material on which the stat bolt 2 is temporarily placed is moved to perform laser welding along the welding path. It is also possible to do so. Also, instead of fixing either one, the same effect can be realized by moving the both relatively.

1 decorative material (plate material), 2 stat bolt (weld member), 3 laser welding head, 4 welding line, 5 first welding line, 21 stat bolt flange, 101 laser output increase rate, 102 laser output decrease rate, P1 welding start position, P2 main welding start position, P3 main welding end position, P4 welding end position, P11 first welding start position, P12 first welding end position, P21 second welding start position, P22 second time Main welding start position, P23 second main welding end position, P24 second welding end position, LO1 main laser output, LO2 initial laser output, LO3 first main laser output, LO4 second main laser output.

Claims (3)

A laser welding method for fixing a member to be welded to a plate material by laser welding,
A member temporary placing step of temporarily placing the welded member on the plate material,
When laser welding the member to be welded to the plate member, starting from a welding start position on the plate member, passing through one end of the member to be welded and the other end of the member to be welded, welding on the plate member And a welding step of performing laser welding along a welding path whose end point is the end point,
The welding process is
In the welding path from the welding start position to the one end of the member to be welded, the laser output is gradually increased from the initial laser output at the welding start position and is preset at one end of the member to be welded. Welding start process that performs welding by upslope control that raises to laser output,
In the welding path from one end of the member to be welded to the other end of the member to be welded, a main welding step of performing welding while maintaining the laser output at the main laser output,
In the welding path from the other end of the member to be welded to the welding end position, the laser output is gradually reduced from the main laser output at the other end of the member to be welded at the welding end position. And a welding termination step of performing welding by down-slope control to reduce the initial laser output. The welding process is
In the main welding path between the first welding start position and the first welding end position defined on the welding path of the member to be welded, the first laser output higher than the main laser output is used. A first welding step for carrying out welding,
The laser welding method according to claim 1, further comprising: a second welding step of performing a second welding by the welding start step, the main welding step, and the welding end step over the welding path. The 2nd welding process, the first time in accordance with the distortion amount of the plate caused by the welding process to reconfigure the laser output used in the present welding process, the welding start process, the main welding process, the The laser welding method according to claim 2, wherein the second welding is performed in the welding ending step.

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