Patent Description:
When a laser welding machine irradiates a weld position on a sheet metal with a laser beam to weld the weld position, the laser welding machine blows, to the weld position, shielding gas that inhibits molten metal from reacting with oxygen. Various nozzles are selectively mounted and used on the welding head of the laser welding machine in accordance with the type of a product to be welded or the position of the weld position in the product (see Patent Literature <NUM>).

For example, at the time of welding a weld position on a ridge portion on the outside of a box-shaped product, a side nozzle is used. In the side nozzle, a gas blow nozzle for blowing shielding gas is provided on the side of a head attachment that is attached to the welding head. When the laser welding machine welds the weld position using the side nozzle, the gas blow nozzle blows shielding gas toward the weld position from the rear in the moving direction of the welding head. The use of the side nozzle has the advantage of excellent shielding of the welding position.

On the other hand, at the time of welding a weld position on a valley portion on the inside of the box-shaped product, a narrow nozzle is used. When the laser welding machine welds the weld position using the narrow nozzle, the narrow nozzle blows shielding gas toward the weld position from directly above the weld position. The narrow nozzle has the advantage of being able to move close to the welding position on the valley portion and blow the shielding gas thereto. <CIT> A discloses a laser welding assembly that has a laser system with a beam guide and beam shaping unit. A laser beam is focused on a weld joint, whereby the effective zone of the laser beam is created on the workpieces to be welded. A working gas nozzle supplies a working gas, in order in particular to reduce shielding of the focused laser beam by a laser induced plasma at the effective zone. A protective gas is supplied to the active zone by means of a protective gas nozzle in order to shield the solidifying melt of the material from the ambient atmosphere. <CIT> discloses a gas shielding device for laser welding of titanium alloys, comprising a main protective gas nozzle for protection of the welding pool and a tail cover for protection of the postwelding high-temperature zone of the welding seam, wherein the main protective gas nozzle is a double-decked nozzle structure; the tail cover is in fixed connection with escape end of the main protective gas nozzle, including a main tail cover and a tail cover connecting component that is connected with the main protective gas nozzle. A side nozzle according to the preamble of independent claim <NUM> is disclosed in <CIT>.

In a case where the laser welding machine welds both the weld position on the ridge portion and the weld position on the valley portion, an operator needs to attach the side nozzle to the welding head at the time of welding the weld position on the ridge portion and the narrow nozzle to the welding head at the time of welding the weld position on the valley portion. When the side nozzle is newly attached to the welding head by replacing the nozzle, the positioning of the gas blow nozzle relative to the weld position is required. The background art has room for improvement in that the replacement of the nozzle attached to the welding head is complicated, and in addition, takes time for positioning and the like.

It is desired to develop a side nozzle, a laser welding machine, and a laser welding method capable of welding both a weld position on a ridge portion and a weld position on a valley portion using the side nozzle as a nozzle attached to a welding head.

According to a first aspect of one or more embodiments, there is provided a side nozzle including: a head attachment attached to a welding head of a laser welding machine and including an opening through which a laser beam emitted from the welding head for irradiation to a weld position passes; and a gas blow nozzle attached to a side of the head attachment and configured to blow shielding gas to the weld position. The gas blow nozzle includes a main nozzle that is disposed closer to the head attachment and is supplied with the shielding gas by a first gas pipe, and a sub-nozzle that is disposed so as to be adjacent to the main nozzle and farther away from the head attachment than the main nozzle and is supplied with the shielding gas by a second gas pipe. The sub-nozzle is removable from the main nozzle.

According to a second aspect of one or more embodiments, there is provided a laser welding machine including: a laser oscillator; a welding head to which a laser beam emitted from the laser oscillator is supplied; and a side nozzle attached to the welding head. The side nozzle includes a head attachment attached to the welding head and including an opening through which the laser beam emitted from the welding head for irradiation to a weld position passes, and a gas blow nozzle attached to a side of the head attachment and configured to blow shielding gas to the weld position. The gas blow nozzle includes a main nozzle that is disposed closer to the head attachment and is supplied with the shielding gas by a first gas pipe, and a sub-nozzle that is disposed so as to be adjacent to the main nozzle and farther away from the head attachment than the main nozzle and is supplied with the shielding gas by a second gas pipe. The sub-nozzle is removable from the main nozzle.

According to a third aspect of one or more embodiments, there is provided a laser welding method including: supplying a laser beam emitted from a laser oscillator to a welding head; irradiating a weld position with the laser beam supplied to the welding head via a head attachment that is provided in a side nozzle, is attached to the welding head, and includes an opening through which the laser beam passes; blowing, at a time of welding a weld position on a ridge portion on an outside of a product, shielding gas from a main nozzle and a sub-nozzle to the weld position with a gas blow nozzle that is attached to a side of the head attachment in a state where the main nozzle and the sub-nozzle are integrated, the main nozzle being disposed closer to the head attachment and being supplied with the shielding gas by a first gas pipe, the sub-nozzle being disposed so as to be adjacent to the main nozzle and farther away from the head attachment than the main nozzle and being supplied with the shielding gas by a second gas pipe; and blowing, at a time of welding a weld position on a valley portion on an inside of the product, the shielding gas from the main nozzle to the weld position with the gas blow nozzle in a state where the sub-nozzle is separated from the main nozzle and only the main nozzle is provided.

According to the side nozzle, laser welding machine, and laser welding method of one or more embodiments, both the weld position on the ridge portion and the weld position on the valley portion can be welded using the side nozzle as a nozzle attached to the welding head.

A side nozzle, a laser welding machine, and a laser welding method according to one or more embodiments will be described below with reference to the accompanying drawings.

In <FIG>, a robot-type laser welding machine <NUM> includes an articulated robot <NUM>, a welding head <NUM>, a side nozzle <NUM> attached to the welding head <NUM>, and a laser oscillator <NUM>. The welding head <NUM> is attached to the tip end of an arm <NUM> of the articulated robot <NUM>. The laser oscillator <NUM> is, for example, a fiber laser oscillator. A laser beam emitted by the oscillation of the laser oscillator <NUM> is supplied to the welding head <NUM> via an optical fiber <NUM>. The side nozzle <NUM> irradiates a weld position on a sheet metal W to be welded with the laser beam. The side nozzle <NUM> blows shielding gas made of nitrogen gas or argon gas from a gas blow nozzle toward the weld position.

The detailed structure of the side nozzle <NUM> will be described with reference to <FIG>. As shown in <FIG>, the side nozzle <NUM> includes a head attachment <NUM> attached to the welding head <NUM>. The head attachment <NUM> includes a circular opening 31a at the upper end and a circular opening (not shown) at the lower end. The laser beam emitted from the welding head <NUM>, indicated by a dash-dotted line, passes through the opening 31a at the upper end and the opening at the lower end for irradiation to the weld position.

A gas blow nozzle <NUM> for blowing the shielding gas is attached to the side of the head attachment <NUM>. The gas blow nozzle <NUM> includes a main nozzle <NUM> and a sub-nozzle <NUM>. The main nozzle <NUM> is disposed closer to the head attachment <NUM>. The sub-nozzle <NUM> is disposed so as to be adjacent to the main nozzle <NUM> and farther away from the head attachment <NUM> than the main nozzle <NUM>. The sub-nozzle <NUM> is removable from the main nozzle <NUM>. That is, the main nozzle <NUM> and the sub-nozzle <NUM> are configured to be separable from each other. <FIG> shows a state where the sub-nozzle <NUM> has been removed from the main nozzle <NUM>.

As shown in <FIG> or <FIG>, a first support <NUM> is attached to the main nozzle <NUM> via a sub-nozzle fixing member <NUM>. <FIG> shows a state where the sub-nozzle <NUM> is viewed from the rear surface. An L-shaped fixture <NUM> is screwed to a position above the sub-nozzle <NUM>, and an L-shaped fixture <NUM> projecting upward is screwed to the fixture <NUM>. The sub-nozzle <NUM> is fixed to the main nozzle <NUM> by bringing a side surface <NUM> of the fixture <NUM> and a bottom surface <NUM> of a hook-shaped tip end <NUM> into contact with a side surface <NUM> and a top surface <NUM> of the sub-nozzle fixing member <NUM>, respectively, and tightening a sub-nozzle attachment and removal bolt <NUM>.

As can be understood from <FIG> and <FIG>, the position of the sub-nozzle <NUM> in the direction toward or away from the main nozzle <NUM> is determined by the contact between the side surfaces <NUM>, <NUM>. The position of the sub-nozzle <NUM> in the direction toward or away from the first support <NUM> is determined by the contact of the end face of the fixture <NUM> opposite to the first support <NUM> with the first support <NUM>. Therefore, the main nozzle <NUM> and the sub-nozzle <NUM> are always connected in a constant state.

The first support <NUM> is fixed to a second support <NUM> by a vertical adjustment bolt <NUM>. The vertical position of the first support <NUM> relative to the second support <NUM> is adjustable. The vertical position of the first support <NUM> relative to the second support <NUM> is adjusted, and the vertical adjustment bolt <NUM> is tightened to fix the vertical position of the first support <NUM> relative to the second support <NUM>.

A third support <NUM> is fixed to the head attachment <NUM>. The rotational position of the second support <NUM> relative to the third support <NUM> is adjusted, and the rotation adjusting bolt <NUM> is tightened to fix the rotational position of the second support <NUM> relative to the third support <NUM>.

The rotational position of the gas blow nozzle <NUM> is adjusted in this manner, so that the tip end (lower end) of the gas blow nozzle <NUM> can be moved toward or away from the weld position that is irradiated with the laser beam. The position of the tip end of the gas blow nozzle <NUM> is adjusted to be an appropriate position that is not too far from the weld position while not interfere with the laser beam with which the weld position is irradiated.

When the laser welding machine <NUM> welds the weld position on the valley portion, the gas blow nozzle <NUM> may interfere with a product. In this case, the interference of the gas blow nozzle <NUM> (main nozzle <NUM>) with the product can be avoided by fixing the first support <NUM> at the upward position relative to the second support <NUM>. An arrow-shaped indicator <NUM> is fixed to the second support <NUM> by a bolt <NUM>. The head attachment <NUM> is provided with marks <NUM>, <NUM>. The rotational position of the indicator <NUM> can be adjusted by loosening the bolt <NUM>.

When the gas blow nozzle <NUM> and the first support <NUM> have been positioned downward, an operator adjusts the rotational position of the indicator <NUM> so that the indicator <NUM> points to the lower mark <NUM>, as shown in <FIG> and <FIG>. When the gas blow nozzle <NUM> and the first support <NUM> have been positioned upward, the operator adjusts the rotational position of the indicator <NUM> so that the indicator <NUM> points to the upper mark <NUM>. This makes it easy to determine whether the gas blow nozzle <NUM> is located upward or downward.

The shielding gas is supplied to the main nozzle <NUM> through a gas pipe <NUM> (first gas pipe) for the main nozzle <NUM>. The shielding gas is supplied to the sub-nozzle <NUM> through a gas pipe <NUM> (second gas pipe) for the sub-nozzle <NUM>. The shielding gas is supplied to a gas supply port (not shown) of the main nozzle <NUM> from a supply device for the shielding gas to be supplied to the main nozzle <NUM>. The main nozzle <NUM> blows the shielding gas from the tip end (lower end). The shielding gas is supplied to the gas supply port <NUM> of the sub-nozzle <NUM> from a supply device for the shielding gas to be supplied to the sub-nozzle <NUM>. The sub-nozzle <NUM> blows the shielding gas from the tip end (lower end).

As shown in <FIG>, a one-touch joint <NUM> is provided between the gas supply port <NUM> and a gas pipe connection <NUM>. In the case of removing the sub-nozzle <NUM> from the main nozzle <NUM>, the one-touch joint <NUM> is removed to disconnect the gas pipe <NUM> from the gas supply port <NUM>.

The detailed structure of the gas blow nozzle <NUM> will be described with reference to <FIG>. The main nozzle <NUM> is formed by forming a main conduit <NUM>, made of a through hole with a circular cross section, by a drill in a metal columnar body cut in a shape shown in the drawing. The main nozzle <NUM> is made of copper that is less likely to be melted by the laser beam reflected at the weld position. The inner diameter of the main conduit <NUM> is <NUM>, for example.

The sub-nozzle <NUM> is formed by forming a sub-conduit 322h1 (first sub-conduit) and a sub-conduit 322h2 (second sub-conduit), made of two through holes with a circular cross section, by a drill in a metal plate-shaped body cut in a shape shown in the drawing. The sub-nozzle <NUM> is made of aluminum or an aluminum alloy. The side nozzle <NUM> can be reduced in weight as the sub-nozzle <NUM> is made of aluminum or an aluminum alloy. The reduction in the weight of the side nozzle <NUM> can reduce the load of the articulated robot <NUM> at the time of moving the welding head <NUM> and the side nozzle <NUM>.

The sub-nozzle <NUM> is away from the weld position, and hence the sub-nozzle <NUM> does not melt. The inner diameters of the sub-conduits 322h1, 322h2 are also <NUM>, for example.

The main conduit <NUM> includes an inclined straight portion h1 below a bend h3 and a straight portion h2 above the bend h3. The bend h3 is a boundary between the inclined straight portion h1 and the straight portion h2. The straight portion h2 is substantially parallel to the traveling direction of the laser beam, and the inclined straight portion h1 is inclined from the bend h3 to approach the weld position.

The sub-conduits 322h1, 322h2 include inclined straight portions h11, h21 below the bends h13, h23, and straight portions h12, h22 above the bends h13, h23, respectively. The bends h13, h23 are boundaries between the inclined straight portions h11, h21 and the straight portions h12, h22. The straight portions h12, h22 are substantially parallel to the traveling direction of the laser beam, and the inclined straight portions h11, h21 are inclined from the bends h13, h23, respectively, to approach the weld position.

The bends h3, h13, h23 of the main conduit <NUM> and the sub-conduits 322h1, 322h2 are formed above the center in the height direction of the gas blow nozzle <NUM>. When the upper end of the gas blow nozzle <NUM> at which the shielding gas is injected is the first end, and the lower end from which the shielding gas is blown is the second end, the bends h3, h13, h23 are formed close to the first end relative to the center between the first end and the second end. The shielding gas supplied to the straight portions h2, h12, h22 is bent at the bends h3, h13, h23 in the traveling directions, and the shielding gas proceeds to the inclined straight portions h1, h11, h21.

The inclined straight portions h1, h11, h21 are formed so that the distance between each other becomes narrower from the bends h3, h13, h23 toward the tip end of the gas blow nozzle <NUM>. Therefore, the shielding gas supplied from each of the straight portions h2, h12, h22 at the upper end of the gas blow nozzle <NUM> is blown toward the weld position in a converged state. The tip ends of the inclined straight portions h1, h11, h21 are the outlets of the shielding gas.

Rectifying members <NUM> for rectifying the shielding gas are mounted on the upper ends of the straight portions h2, h12, h22. The inner diameters of the upper ends of the straight portions h2, h12, h22 have been enlarged to <NUM>, and the portions having the enlarged inner diameters are housing portions h20, h120, h220 for housing the rectifying members <NUM>. The rectifying member <NUM> is preferably made of a porous metal material. The porous metal material is made of nickel as an example. The rectifying members <NUM> have a cylindrical shape with a diameter of <NUM> (minus tolerance) and a thickness of about <NUM>, and two rectifying member <NUM> are mounted in each of the housing portions h20, h120, h220 of the straight portions h2, h12, h22.

The laser beam reflected at the weld position may enter the inclined straight portions h1, h11, or h21 from the tip end of the gas blow nozzle <NUM>. With the gas blow nozzle <NUM> including the bends h3, h13, h23, it is possible to reduce the possibility that the laser beam reaches the rectifying member <NUM> and damages the rectifying member <NUM>.

When the side nozzle <NUM> is attached to the welding head <NUM>, and the laser welding machine <NUM> welds a weld position on a ridge portion on the outside of a box-shaped product and a weld position on a valley portion on the inside of the product, for example, the operator selectively uses the gas blow nozzle <NUM> as follows.

As shown in <FIG>, at the time of welding the weld position on the ridge portion on the outside of the product, the operator brings the gas blow nozzle <NUM> into a state where the main nozzle <NUM> and the sub-nozzle <NUM> are integrated. The weld position is irradiated with the laser beam supplied from the welding head <NUM> (not shown in <FIG>) via the welding head <NUM>. At this time, the shielding gas supplied through each of the main conduit <NUM> in the main nozzle <NUM> and the two sub-conduits 322h1, 322h2 in the sub-nozzle <NUM> is blown to the weld position. In the laser welding machine <NUM>, the welding head <NUM> and the side nozzle <NUM> are moved in a moving direction indicated by an arrow, and the main nozzle <NUM> and the sub-nozzle <NUM> blow the shielding gas toward the weld position from the rear in the moving direction.

The gas blow nozzle <NUM> with the main nozzle <NUM> and the sub-nozzle <NUM> integrated blows the shielding gas to the weld position, whereby the weld position is shielded well. Moreover, with the gas blow nozzle <NUM> being configured as shown in <FIG>, the weld position is shielded better when the side nozzle <NUM> including the gas blow nozzle <NUM> is used than when a conventional side nozzle is used. A comparison of the shielding properties between the conventional side nozzle and the side nozzle <NUM> will be described later.

On the other hand, at the time of welding the weld position on the valley portion on the inside of the product, as shown in <FIG>, the operator separates the sub-nozzle <NUM> from the main nozzle <NUM> to bring the gas blow nozzle <NUM> into the state where it includes only the main nozzle <NUM>. At this time, as described above, when the main nozzle <NUM> interferes with the product, the first support <NUM> is fixed at the upward position relative to the second support <NUM> to prevent the main nozzle <NUM> from interfering with the product. The shielding gas supplied through the main conduit <NUM> in the main nozzle <NUM> is blown to the weld position.

The laser welding machine <NUM> moves the welding head <NUM> and the side nozzle <NUM> (not shown in <FIG>) in a moving direction indicated by an arrow, and the main nozzle <NUM> blows the shielding gas toward the weld position from the rear in the moving direction.

The use of only the main nozzle <NUM> as the side nozzle <NUM> so as to weld the weld position on the valley portion on the inside of the product can greatly improve the accessibility to the weld position. The use of only the main nozzle <NUM> as the side nozzle <NUM> can achieve similar accessibility to the weld position as in the case of using a narrow nozzle.

The nozzle to be attached to the welding head <NUM> is maintained in the side nozzle <NUM>, whether the welding is performed on the weld position on the ridge portion on the outside of the product or the weld position on the valley portion on the inside of the product. This eliminates the need to replace the side nozzle <NUM> with a narrow nozzle, making the complicated work of replacing the nozzle mounted on the welding head <NUM> unnecessary. The positional relationship between the weld position and the main nozzle <NUM> remains unchanged even when the sub-nozzle <NUM> is attached to the main nozzle <NUM> or the sub-nozzle <NUM> is separated from the main nozzle <NUM>. This eliminates the need to adjust the angle of the gas blow nozzle <NUM> (main nozzle <NUM>) and readjust the positional relationship between the weld position and the main nozzle <NUM>.

It is only necessary to adjust the vertical position of the gas blow nozzle <NUM> (main nozzle <NUM>) at most in the state where the main nozzle <NUM> and the sub-nozzle <NUM> are integrated and in the state where the sub-nozzle <NUM> is separated from the main nozzle <NUM>.

Next, the shielding property of the conventional side nozzle is compared with that of the side nozzle <NUM>. <FIG> shows a gas blow nozzle <NUM> as a comparative example provided in the conventional side nozzle. The gas blow nozzle <NUM> includes a main conduit mh and two sub-conduits sh1, sh2. The main conduit mh and the sub-conduit sh1 are formed linearly. The sub-conduit sh2 includes a bend sh21 at a position near the lower end. The sub-conduit sh2 is formed linearly from the upper end to a bend sh21. The inner diameters of the main conduit mh and the two sub-conduits sh1, sh2 are <NUM>. The gas blow nozzle <NUM> is made of copper.

The upper ends of the main conduit mh and the two sub-conduits sh1, sh2 are enlarged in inner diameter, and a rectifying member <NUM> for rectifying the shielding gas is mounted in a housing portion of the enlarged inner diameter portion. The rectifying member <NUM> is formed by laminating, for example, ten circular mesh members with a spacer between two mesh members. However, in the comparison of the shielding properties between the conventional side nozzle and the side nozzle <NUM>, the rectifying member <NUM> was used in common.

<FIG> is a photograph obtained by analyzing, with a schlieren device and a high-speed camera, the flow of the shielding gas when the shielding gas is blown from the gas blow nozzle <NUM> with the main nozzle <NUM> and the sub-nozzle <NUM> integrated. The flow rate of the main nozzle <NUM> (main conduit <NUM>) is set to <NUM> liters/minute, and the flow rate of the sub-nozzle <NUM> (the total of the sub-conduits 322h1, 322h2) is set to <NUM> liters/minute. <FIG> is a photograph obtained by analyzing, with the schlieren device and the high-speed camera, the flow of the shielding gas when the shielding gas is blown from the gas blow nozzle <NUM> shown in <FIG>. The flow rate of the main conduit mh is <NUM> liters/minute, and the total flow rate of the sub-conduits sh1, sh2 is <NUM> liters/minute.

A comparison between <FIG> shows that a laminar flow in <FIG> in which the gas blow nozzle <NUM> is used is less turbulent than a laminar flow in <FIG> in which the gas blow nozzle <NUM> is used. The reason for the large amount of turbulence in <FIG> is thought to be that the direction in which the shielding gas flows changes due to the bend sh21 having been formed at a position near the lower end of the sub-conduit sh2. As described above, the bends h3, h13, h23 of the main conduit <NUM> and the sub-conduits 322h1, 322h2 are located above the center in the height direction of the gas blow nozzle <NUM>. It is preferable that each of the main conduit <NUM> and the sub-conduits 322h1, 322h2 is linear without a bend at least from the center to the lower end in the height direction of the gas blow nozzle <NUM>.

Note that the smaller the inner diameter of the conduit, the faster the flow velocity of the shielding gas becomes, which causes a turbulent flow. In the gas blow nozzle <NUM>, it is considered that the larger the inner diameter is in an appropriate range, the more the gas blow nozzle <NUM> has an auxiliary effect for reducing the turbulent flow.

The processing quality in the case of using the gas blow nozzle <NUM> is compared with that in the case of using the gas blow nozzle <NUM> with reference to <FIG> show an example in which two sheet metals of stainless steel (SUS304) having a thickness of <NUM> are welded by half-drawn angle joining. The half-drawn angle joining is welding with the end of the surface of one sheet metal positioned at the center of the thickness of the other sheet metal.

Argon gas is used as the shielding gas, the flow rate of the main conduit <NUM> or mh is set to <NUM> liters/minute, and the flow rate of the sub-conduits 322h1, 322h2 or sh1, sh2 is set to <NUM> liters/minute.

As shown in <FIG>, when the gas blow nozzle <NUM> is used, the processing quality is good at the corner between the two sheet metal plates, which is the weld position, from the right side end as the starting end of the welding to the left side end as the terminal end of the welding. On the other hand, as shown in <FIG>, when the gas blow nozzle <NUM> is used, bead burning has occurred and the processing quality is not good in a range surrounded by a dash-dotted line on the start end side of the welding at the corner between the two sheet metal plates. In <FIG>, the welding is performed without using a gas retaining jig to compare the capabilities for shielding the weld position.

Further, the shielding property of the rectifying member <NUM> made of the porous metal material is compared with that of the rectifying member <NUM> in which ten mesh members are laminated. As described above, the rectifying member <NUM> is used in the gas blow nozzle <NUM> provided in the conventional side nozzle. For comparing the shielding properties between the rectifying member <NUM> and the rectifying member <NUM>, the side nozzle <NUM> including the gas blow nozzle <NUM> is commonly used, and the rectifying member <NUM> and the rectifying member <NUM> are selectively mounted in the housing portions h20, h120, h220 to analyze the flow of the shielding gas.

<FIG> is a photograph obtained by analyzing, with the schlieren device and the high-speed camera, the flow of the shielding gas when the shielding gas is blown from the gas blow nozzle <NUM>, using the rectifying member <NUM> made of the porous metal material. <FIG> is a photograph obtained by analyzing, with a schlieren device and a high-speed camera, the flow of the shielding gas when the shielding gas is blown from the gas blow nozzle <NUM>, using the rectifying member <NUM> in which the ten mesh members are laminated. In both cases, the flow rate of the main nozzle <NUM> (main conduit <NUM>) is set to <NUM> liters/minute, and the flow rate of the sub-nozzle <NUM> (the total of the sub-conduits 322h1, 322h2) is set to <NUM> liters/minute.

A comparison between <FIG> shows that a laminar flow in <FIG> in which the rectifying member <NUM> made of the porous metal material is used is less turbulent than a laminar flow in <FIG> in which the rectifying member <NUM> with the laminated ten mesh members is used. The conditions except for the rectifying member are the same, and it can thus be seen that the rectifying member <NUM> made of the porous metal material has an effect of bringing the flow of the shielding gas close to a laminar flow.

The processing qualities are compared between the case of using the rectifying member <NUM> and the case of using the rectifying member <NUM> with reference to <FIG> show examples of rounding on sheet metals. The rounding is a process of rounding the corner. <FIG> show a case where the rectifying member <NUM> is used, and <FIG> show a case where the rectifying member <NUM> is used.

Argon gas is used as the shielding gas, the flow rate of the main conduit <NUM> is set to <NUM> liters/minute, and the flow rate of the sub-conduits 322h1, 322h2 is set to <NUM> liters/minute.

<FIG> are enlarged photographs of ends, which are the start end sides of the welding, circled by dash-dotted lines shown in <FIG>, respectively. As is apparent from a comparison between <FIG>, bead burning is less and the processing quality is better in <FIG> in which the rectifying member <NUM> made of the porous metal material is used. The reason why the processing quality is better in <FIG> than in <FIG> is thought to be that the shielding gas blown from the gas blow nozzle <NUM> forms a laminar flow with less turbulence when the rectifying member <NUM> is used.

In the case of using the rectifying member <NUM>, there is also an effect of facilitating the replacement of the rectifying member <NUM> when the rectifying member <NUM> is damaged and needs to be replaced. In the case of using the rectifying member <NUM> in which the circular mesh members are laminated, when the rectifying member <NUM> is damaged and needs to be replaced, the man-hour of manufacturing the rectifying member <NUM> by laminating circular mesh members is required, thus making the work to replace the rectifying member <NUM> complicated.

As described above, the side nozzle <NUM> according to one or more embodiments includes the gas blow nozzle <NUM> with the sub-nozzle <NUM> removable from the main nozzle <NUM>. Therefore, it is possible to weld both the weld position on the ridge portion and the weld position on the valley portion while using one side nozzle <NUM> as a nozzle to be attached to the welding head <NUM>. There is no need to replace the nozzle attached to the welding head <NUM> with a narrow nozzle at the time of welding the weld position on the valley portion. At this time, the side nozzle <NUM> can be reduced in weight as the main nozzle <NUM> is made of copper and the sub-nozzle <NUM> is made of aluminum or an aluminum alloy.

The gas blow nozzle <NUM> is preferably configured as follows. The main nozzle <NUM> includes the main conduit <NUM> and two sub-conduits 322h1, 322h2 of the sub-nozzle <NUM>. The main conduit <NUM> and the sub-conduits 322h1, 322h2 include the straight portions h2, h12, h22 formed closer to the first end at which the shielding gas is injected, and the inclined straight portions h1, h11, h21 formed closer to the second end from which the shielding gas is blown. The bends h3, h13, h23 are formed between the straight portions h2, h12, h22 and the inclined straight portions h1, h11, h21. The bends h3, h13, h23 are formed close to the first end relative to the center between the first end and the second end, and no bend is formed in the inclined straight portions h1, h11, h21.

The gas blow nozzle <NUM> configured in this manner can make the flow of the shielding gas less turbulent to get close to a laminar flow, and the processing quality can be improved.

Each of the straight portions h2, h12, h22 on the first end side is preferably mounted with the rectifying member <NUM> that is made of a porous metal material and rectifies the shielding gas. When the rectifying member <NUM> made of the porous metal material is mounted, the flow of the shielding gas can be made less turbulent to get closer to a laminar flow than when the rectifying member <NUM> in which the mesh members are laminated is mounted. Thus, processing quality can be further improved.

In the laser welding machine <NUM> according to one or more embodiments, the side nozzle <NUM> configured as described above is attached to the welding head <NUM>, so that it is possible to weld both the weld position on the ridge portion and the weld position on the valley portion without replacing the nozzle attached to the welding head <NUM>. In the laser welding machine <NUM> according to one or more embodiments, the gas blow nozzle <NUM> has a specific configuration as described above, enabling the welding of the sheet metal W with good processing quality.

In the laser welding method according to one or more embodiments, at the time of welding the weld position on the ridge portion on the outside of the product, the shielding gas is blown to the weld position, with the main nozzle and the sub-nozzle integrated. In the laser welding method according to one or more embodiments, at the time of welding a weld position on the valley portion on the inside of the product, the shielding gas is blown to the weld position, with only the main nozzle provided. Hence it is possible to weld the weld positions on both the ridge portion and the valley portion without replacing the nozzle attached to the welding head <NUM> with a narrow nozzle.

Claim 1:
A side nozzle (<NUM>) comprising:
a head attachment (<NUM>) configured to be attached to a welding head (<NUM>) of a laser welding machine (<NUM>) and including an opening (31a) through which a laser beam emitted from the welding head (<NUM>) for irradiation to a weld position passes; and
a gas blow nozzle (<NUM>) attached to a side of the head attachment (<NUM>) and configured to blow shielding gas to the weld position, wherein
the gas blow nozzle (<NUM>) includes
a main nozzle (<NUM>) that is disposed closer to the head attachment (<NUM>) and is supplied with the shielding gas by a first gas pipe (<NUM>), and
a sub-nozzle (<NUM>) that is disposed so as to be adjacent to the main nozzle (<NUM>) and farther away from the head attachment (<NUM>) than the main nozzle (<NUM>) and is supplied with the shielding gas by a second gas pipe (<NUM>),
characterized in that
the sub-nozzle (<NUM>) is removable from the main nozzle (<NUM>),
the main nozzle (<NUM>) is made of copper, and
the sub-nozzle (<NUM>) is made of aluminum or an aluminum alloy.