JP2007275982A - Laser welding method and clearance straightening device in base metal for laser welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser welding method where there is no need of forming projections and embossed parts on base metal sides, and further, the size of a fine clearance to be secured between the base metals can be correctly set. <P>SOLUTION: Reinforces Wa, Wb to be the objective base metals in laser welding are superimposed each other while being positioned with rocket pins 2, and an inert gas is blown into the space therebetween with a gas nozzle 11. The reinforce Wb on the upper side is floated up to the reinforce Wa on the lower side with gas pressure, so as to form a fine clearance G therebetween, and the size of the clearance G is regulated with a stopper apparatus 10. The welding is performed in such a manner that a laser beam La is emitted from the side of the reinforce Wb in a state where the fine clearance G is secured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser welding method suitable for welding in the form of a lap weld joint using a surface-treated steel plate as typified by a plated steel plate as a base material, and a base metal gap correction device for laser welding.

For example, when laser welding is performed in the form of a lap weld joint using a galvanized steel sheet as the base material, the galvanized layer on the surface of the base material evaporates and scatters due to laser energy, causing weld defects such as porosity in the weld bead. It is known to be easy. On the other hand, it is also known that if laser welding is performed with a small gap between the weld base materials, the gas formed by the evaporation of the galvanized layer escapes and the occurrence of the above welding defects can be suppressed. ing. And as a method of setting a minute gap between the base materials, for example, as described in Patent Documents 1 and 2, a method of forming minute protrusions and embossed portions in the vicinity of the welded portion of the base material, and the base material itself are omitted in cross section in advance. Methods such as bending into a crank shape have been proposed.
JP 2001-162388 A Japanese Patent Laying-Open No. 2005-297026

  In the conventional techniques represented by Patent Documents 1 and 2, the occurrence of welding defects such as porosity is suppressed by setting a minute gap, but conversely if the size of the minute gap is not strictly controlled. There is a concern that the quality of welding is deteriorated, and there is a problem that the size of the minute gap is not stable depending on the thickness of the base material on the upper side and the position pressed by the clamping means or the like.

  In particular, when a minute gap is to be secured by forming a minute protrusion in advance on the base material side, it is difficult to accurately process a protrusion having a height of about 0.15 to 0.25 mm depending on the thickness of the base material plate. Therefore, there was a limit to the maintenance of the projection or emboss height accuracy.

  The present invention has been made paying attention to such problems, and it is not particularly necessary to form minute protrusions or the like on the base material side, and the size of the minute gap to be secured between the base materials is accurately determined. It is an object of the present invention to provide a laser welding method and a laser welding base material gap correction device which can be set.

  The invention according to claim 1 superimposes at least two metal plates including a surface-treated metal plate subjected to surface treatment such as a plated steel plate as a base material, and at least a welded portion, and the surface-treated metal plate and A method in which laser welding is performed in a state in which a minute gap is secured between the metal plate and the other metal plate facing each other, wherein an inert gas is introduced between the surface-treated metal plate and the other metal plate facing the metal plate. By blowing, the two metal plates are separated from each other, a minute gap is secured between them, and welding is performed by laser light irradiation in a state where both the metal plates are regulated so that the minute gap becomes a predetermined size. It is characterized by giving.

  For example, argon (Ar) or helium (He) is used as the inert gas.

  In this case, as described in claim 2, an inert gas is blown between the surface-treated metal plate and the other metal plate facing the metal plate, and an inert gas is blown between the two metal plates. While ensuring a minute gap between the plates, it is possible to actively generate a flow of inert gas in the minute gap by blowing out inert gas from the position where the minute gap is opened to the outside. It is desirable for positive exhaust of harmful gas formed by evaporation of the plating layer on the surface of the base material.

  Further, in strictly controlling the size of the minute gap formed between the two metal plates, as described in claim 3, the surface-treated metal is used so that the minute gap has a predetermined size. It is desirable to regulate the mutual separation distance between the two metal plates with a regulating means that contacts the plate and the other metal plate facing it.

  The invention according to claim 5 captures the technique according to claim 1 as a laser welding base material gap correction device, and includes at least two surface-treated metal plates that have been surface-treated as the base material. In performing laser welding in a state in which a minute gap is secured between the surface-treated metal plate and the other metal plate facing the metal sheet at least at the welding site, the minute gaps have a predetermined size. It is assumed that the apparatus regulates at least two metal plates. In addition, each metal is formed such that a minute gap between the surface-treated metal plate and the other metal plate facing the surface-treated metal plate is separated from each other by blowing the inert gas to a predetermined size. A regulating means that abuts against the plate and regulates the position; and an inert gas blowing means that blows an inert gas between the surface-treated metal plate and the other metal plate facing the surface-treated metal plate to separate the two metal plates from each other; It is characterized by having.

  Therefore, in at least the inventions according to claims 1 and 5, by blowing an inert gas between the metal plates as the base material, the metal plates are separated from each other, and a predetermined minute gap is ensured. The inert gas works effectively in making the atmosphere around the welded portion an inert atmosphere.

  According to the first aspect of the present invention, a minute gap having a predetermined size can be secured without processing a minute protrusion or an embossed portion between metal plates as a base material in advance, so that the number of processing steps can be reduced. At the same time, there is no need to maintain the rigorous protrusion or emboss height accuracy maintenance work as in the past, and unlike the conventional method, the metal plates are connected to each other by inert gas pressure instead of pressing the base materials together. Since the minute gap is secured by floating or separating from each other, the variation in the size of the minute gap is eliminated, and the size of the minute gap is stabilized and can contribute to the improvement of the welding quality.

  According to the fifth aspect of the present invention, at least the regulation means and the inert gas blowing means can achieve the intended purpose, and therefore the size of the minute gap can be stabilized under a very simple configuration. As a result, the welding quality can be improved.

  FIGS. 1 to 3 are views showing a preferred embodiment of the present invention. In this example, a trunk made of, for example, a galvanized steel sheet, which is disposed inside a trunk lid of an automobile and functions as a trunk lid inner panel. For the lid drain force (hereinafter, simply referred to as “main reinforcement”) Wa, the hinge reinforcement (hereinafter referred to simply as “galvanized steel plate”) made of the same galvanized steel plate with respect to the hinge mounting position of the main reinforcement force Wa serving as the parent body. An example in which Wb (referred to as “sub-reinforce”) is welded is shown. 1 is a schematic plan view of a welding assembly facility using the jig base 1 as a base, FIG. 2 is an enlarged cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is taken along line BB in FIG. Each of the cross-sectional views is shown.

  As shown in FIGS. 1 and 2, a plurality of window-like holes H are formed in the main reinforcement Wa, and are areas other than the holes H and correspond to hinge mounting positions for trunk lids on both sides. After the sub-reinforce Wb is superposed on the portion, welding is joined by laser welding in the form of a so-called lap weld joint. La represents a laser beam for laser welding, and Bw represents a welding bead by laser welding. Further, in both the main reinforcement Wa and the sub reinforcement Wb, a locating hole R1 is formed in advance at a position where it does not interfere with the weld bead Bw or a gas introduction hole R2 described later. By inserting the common locating pin 2 into the hole R1, the relative positioning of both is performed.

  As shown in FIGS. 2 and 3 in addition to FIG. 1, a plurality of clampers 3 are provided on the jig base 1, and the main reinforcement Wa serving as a base is positioned on the jig base 1 by the clampers 3. It is designed to clamp. The clamper 3 has a known structure in which, for example, a clamp arm 6 driven by an air cylinder (clamp cylinder) 5 is supported on a bracket 4 fixed to the jig base 1 in a swingable manner. The main reinforcement Wa is firmly clamped by clamping with the receiving surface 4a and the clamp arm 6 on the side.

  In addition to the clamper 3, a plurality of toggle-type stopper devices 7 are provided on the jig base 1 and in the vicinity of the portion corresponding to the hinge mounting position of the main reinforcement Wa. Although this stopper device 7 is mechanically similar to the clamper 3 described above, its function is greatly different from that of the clamper 3, and a main reinforcement Wa, which will be described later, and a secondary reinforcement Wb superposed thereon are arranged. Prior to the welding, as shown in FIG. 2, the minute gap G is positively secured between the main reinforcement Wa and the subsidiary reinforcement Wb, and the minute gap G is regulated to a predetermined size. It has a function. The stopper device 7 has a known structure in which, for example, a stopper arm 10 driven by an air cylinder 9 is supported by a bracket 8 as a base member fixed to the jig base 1 so as to be able to swing and swing. Thus, the total thickness dimension when the main reinforcement Wa and the sub reinforcement Wb are overlapped while securing a minute gap G therebetween is regulated by the receiving surface 8a on the bracket 8 side and the stopper arm 10. It will be.

  Further, at least two locating pins 2 project from the post 12 on the jig base 1 side, and are formed in advance on the main reinforcement wa side and the sub-reinforce Wb side with respect to these locating pins 2. By inserting the locate holes R1 respectively, relative positioning of the main reinforcement Wa and the sub reinforcement Wb is performed with the locate pin 2 as a reference.

  Here, as shown in FIG. 2, for example, a circular gas introduction hole R2 is formed in advance on the main reinforcement Wa side separately from the locating hole R1, and an inert gas is blown on the jig base 1 side. A tip funnel-shaped gas nozzle 11 which functions as a means is attached upward via a post 13. The gas nozzle 11 is connected to an inert gas supply source (not shown) for supplying an inert gas such as argon (Ar) or helium (He), and is inert from the gas nozzle 11 as necessary. Gas can be blown out.

  In addition, the inert gas is blown out from the gas nozzle 11 by actively feeding between the main reinforcement Wa and the sub reinforcement Wb as shown in FIG. The sub-reinforce Wb is levitated from the lower main reinforcement Wa to positively separate them from each other, thereby ensuring a minute gap G between the two.

  Therefore, according to such a welding assembly facility, first, all the clampers 3 and the stopper devices 7 are in an unclamped state, and then on the jig base 1, more specifically on the receiving surfaces 4a and 8a. The main reinforcement Wa serving as the mother body is placed, and positioning is performed by engaging the locate hole R1 and the locate pin 2 on the main reinforcement Wa side. Then, the clamper 3 is clamped to firmly clamp the main reinforcement Wa to the jig base 1.

  At this time, since the gas introduction hole R2 on the main reinforcement Wa side and the position of the gas nozzle 11 are matched in advance, when the main reinforcement Wa is positioned and clamped with respect to the jig base 1 as described above, the gas introduction hole The gas nozzle 11 comes into pressure contact with the peripheral edge of R2. In order to stabilize the pressure contact state of the gas nozzle 11 with respect to the peripheral portion of the gas introduction hole R2 as described above, the gas nozzle 11 itself can be moved up and down by a predetermined amount and elastically moved upward by an elastic body or the like. It is desirable to be energized.

  Subsequently, the secondary reinforcement Wb is superimposed on the primary reinforcement Wa, and the relative positioning of the primary reinforcement Wa and the secondary reinforcement Wb is performed by engaging the locate hole R1 and the locate pin 2 on the secondary reinforcement Wb side. I do. When the relative positioning between the main reinforcement Wa and the sub-reinforce Wb is completed, the stopper device 7 is clamped to position the stopper arm 10 on the upper side of the sub-force Wb as shown in FIG.

  In this state, even if the main reinforcement Wa and the sub-reinforce Wb are in a polymerized state, the sub-reinforce Wb is not lifted with respect to the main reinforcement Wa. The minute gap G is not secured between them, and the tip of the stopper arm 10 is not in contact with the sub-reinforce Wb.

  Further, the plate thicknesses of the main reinforcement Wa and the sub-reinforce Wb are known, but the size of the minute gap G to be ensured between the main reinforcement Wa and the sub-reinforce Wb when they are laser-welded. The length is determined in advance according to the plate thickness or the like (for example, the minute gap G = 0.15 to 0.25 mm). Therefore, when the stopper device 7 is clamped as described above, the dimensions of the both of the reinforcements Wa and Wb are set so as to be secured between the distal end surface of the stopper arm 10 and the receiving surface 8a. The clamp limit position of the stopper arm 10 is adjusted in advance so as to be the sum total with the set value of the minute gap G.

  Thus, when the relative positioning of the main reinforcement Wa and the sub reinforcement Wb is completed, an inert gas is blown from the gas nozzle 11 between the reinforcements Wa and Wb. As the inert gas is blown in, the sub-force Wb rises from the main force Wa while being guided by the locate pin 2, and the two forces Wa and Wb are separated from each other. Then, the upper limit position of the sub-reinforce Wb is restricted by the stopper arm 10 so that a minute gap G having a preset size is secured between the two reinforces Wa and Wb. At the same time, the minute gap G is opened to the outside through the opening Q at the peripheral edge of the sub reinforcement Wb.

  Along with this external opening, an inert gas flow F is generated from the gas introduction hole R2 toward the opening Q at the peripheral edge of the auxiliary reinforcement wb through the space of the minute gap G as a passage. The reinforcement Wb can self-hold the floating state from the main reinforcement Wa and maintain the size of the minute gap G at a predetermined size. In addition, since the size of the minute gap G is regulated by bringing the auxiliary reinforcement Wb levitated by the blowing pressure of the inert gas into contact with the stopper arm 10 of the stopper device 3, the size of the minute gap G is controlled. It becomes possible to maintain with high accuracy.

  In this state, laser welding is performed by irradiating the laser beam La as shown in FIG. 2 to a position to be the welding bead Bw on the auxiliary reinforcement Wb side by, for example, remote laser welding.

  In this case, because the reinforcements Wa and Wb made of galvanized steel sheet are welded together, the plating layer on the surface of each of the reinforcements Wa and Wb evaporates upon receiving laser energy, and a gas harmful to the welding quality is generated. However, these gases are instantaneously discharged to the outside of the minute gap G with the flow F of the inert gas, and the weld quality can be expected to be improved by forming an inert atmosphere with the inert gas at and around the welding site. It becomes like this.

  As described above, according to the present embodiment, the sub-reinforce Wb is lifted with respect to the main reinforce Wa with the pressure of the inert gas, and the lifted sub-reinforce Wb is brought into contact with the stopper arm 10 of the stopper device 3. By doing so, the minute gap G between the two is maintained at a predetermined size, so that the intended purpose can be obtained without forming projections or embossed portions in advance in the reinforcements Wa or Wb as in the prior art. In addition, the size of the minute gap G is stabilized as compared with the case where the reinforcements Wa and Wb are pressed against each other and the size of the gap G is maintained at a predetermined size as in the prior art. It is possible to maintain the size of the minute gap G with high accuracy.

  In addition, since the locate pin 2 for relative positioning between the two reinforcements Wa and Wb is also used as a guide when the secondary reinforcement Wb is levitated with respect to the main reinforcement Wa, other guide mechanisms are provided. This is unnecessary and can contribute to simplification of equipment.

  4 and 5 are diagrams showing a second embodiment of the present invention, in which the same reference numerals are given to the portions common to the first embodiment.

  In the second embodiment, a main reinforcement Wa and a sub-reinforce Wb, which have been drawn into a curved shape in advance, are overlapped, and the two slopes M are welded together by remote laser welding. In this case, interference between the laser beam La and the stopper device 7 is avoided.

  As shown in FIGS. 4 and 5, in the remote laser welding method, the laser beam La having a relatively long focal length is irradiated to the welding position with the reflection mirror or the laser processing head 14, so that both of the reinforcement forces Wa, If Wb is to be welded at the slope M, for example, the stopper device 7 on the right side of FIG. 5 (here 7A) and the laser beam La may interfere with each other. Therefore, in the present embodiment, the maximum height position (the maximum height position of the stopper arm 10) of the stopper device 7A on the side close to the slope M is held lower than the uppermost surface position of the main reinforcement Wa, and the stopper Interference between a part of the device 7A and the laser beam La having a long focal length is effectively avoided.

  It goes without saying that the same effects as those of the first embodiment can be obtained also in the second embodiment.

Plane explanatory drawing which shows the 1st Embodiment of this invention. Explanatory sectional explanatory drawing in alignment with the AA of FIG. Explanatory sectional explanatory drawing which follows the BB line of FIG. Plane | planar explanatory drawing which shows the 2nd Embodiment of this invention. Expansive sectional explanatory drawing which follows the CC line of FIG.

Explanation of symbols

2 ... Locate pin 7 ... Stopper device (regulation means)
8 ... Bracket (base member)
10 ... Stopper arm 11 ... Gas nozzle (inert gas blowing means)
Bw ... Welding bead F ... Inert gas flow G ... Small gap La ... Laser beam R1 ... Locate hole R2 ... Locate hole Wa ... Trunk lamin drain force (surface-treated metal plate as a base material)
Wb ... Hinge reinforcement (surface-treated metal plate as a base material)

Claims (8)

At least two metal plates including a surface-treated metal plate that has been surface-treated as a base material are overlapped, and at least a welded portion has a minute gap between the surface-treated metal plate and the other metal plate facing it. A method in which laser welding is performed in a secured state,
By blowing an inert gas between the surface-treated metal plate and the other metal plate facing the surface-treated metal plate, the two metal plates are separated from each other to ensure a minute gap therebetween, and the minute gap is predetermined. A laser welding method comprising performing welding by laser light irradiation in a state where both metal plates are regulated so as to have a size of 2 mm.   While ensuring a minute gap between the two metal plates by blowing an inert gas between the surface-treated metal plate and the other metal plate facing it from the hole formed in one of them 2. The laser welding method according to claim 1, wherein an inert gas flow is actively generated in the minute gap by blowing out an inert gas from a position where the minute gap is opened to the outside. 3. .   The distance between the two metal plates is regulated by regulating means that abuts on the surface-treated metal plate and the other metal plate facing the surface-treated metal plate so that the minute gap has a predetermined size. The laser welding method according to claim 1 or 2.   Prior to the blowing of the inert gas, relative positioning of both metal plates is performed with a locate pin penetrating the surface-treated metal plate and the other metal plate facing the surface-treated metal plate. The laser welding method described in 1. At least two metal plates including a surface-treated metal plate that has been surface-treated as a base material are overlapped, and at least a welded portion has a minute gap between the surface-treated metal plate and the other metal plate facing it. A device that regulates at least two metal plates so that the minute gap has a predetermined size when performing laser welding in a secured state,
The surface-treated metal plate and the other metal plate facing the surface-treated metal plate are separated from each other by the blowing of the inert gas, so that the minute gap between the two is in contact with each metal plate so as to have a predetermined size. A regulation means for regulating the position,
An inert gas blowing means for blowing an inert gas between the surface-treated metal plate and the other metal plate facing the metal plate to separate the two metal plates from each other;
A base metal gap correction device for laser welding, comprising:   An inert gas is blown in between the surface-treated metal plate and the other metal plate facing the metal plate with an inert gas blowing means between the two metal plates. While ensuring the gap, the inert gas flow is actively generated in the minute gap by blowing the inert gas from the position where the minute gap is opened to the outside. The base material gap correction apparatus for laser welding according to claim 5.   6. A locating pin for positioning the two metal plates relative to each other through the surface-treated metal plate and the other metal plate facing the surface-treated metal plate prior to blowing the inert gas. Or a base material gap correction device for laser welding according to 6;   The restricting means is a stopper device using a toggle mechanism, and the base member of the stopper device is swung to one of the surface-treated metal plate and the other metal plate facing it, and to the base member. The laser welding base metal gap correction device according to any one of claims 5 to 7, wherein a stopper arm supported so as to be movable comes into contact with the other metal plate.

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