JP5141034B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a laser processing apparatus that performs processing such as welding, drilling, and cutting with a laser beam, and more particularly to a laser processing apparatus and a laser processing method that perform processing by irradiating a laser beam with a long focal point from a position away from a welding site. Is.

  The laser welding equipment used in the mass production process uses, for example, a multi-degree-of-freedom welding robot as a welding mother machine, and a laser processing head (welding torch) is provided at the tip of the welding robot, while a YAG laser that can be transmitted by an optical fiber cable The mainstream is that the laser beam is irradiated from the machining head to the welded part using a laser beam or the like. However, for example, when welding points are scattered over a wide range, it takes time to move the machining head, and it is not possible to cope with welding at a site where the machining head interferes, such as a narrow groove.

  Therefore, in recent years, a technique called a remote laser (scanner laser) welding method, in which welding is performed by irradiating with a long-focus laser beam (laser beam) from a position away from the welding site, has attracted attention (see below). Patent Document 1). In this remote laser welding method, by scanning the laser beam through the optical deflection optical system, it is possible to move the laser beam instantaneously to the next welding point and perform the next welding. It is also possible to adjust the focal length.

  However, since the remote laser welding method handles a long-focus laser beam, there are the following problems. That is, when laser welding is performed in a state where components are positioned with a jig, laser light leaks from the back side of the welded portion. This leaked laser light is used to detect peripheral devices such as jig gauge posts and pneumatic equipment (air cylinders, air hoses) for fixing parts, sensors attached to the equipment, signal cables, etc. It may hit accessory parts and damage them. In addition, the power density of the long-focus laser beam does not decrease so much even if it is far away from the focus. The same applies to laser light leaking from the back side of the welding point. Since the power density is kept high even when it is far away from the focal point, the above-mentioned peripheral jigs and devices are often greatly damaged. .

  On the other hand, it is known that when laser welding is performed by irradiating a butt portion of a plate material with a laser beam from a laser head, bulging of the meat occurs on the front and back surfaces of the weld surface. Therefore, the plasma generated at the time of laser welding is removed by spraying a shield gas from the plasma removal nozzle provided adjacent to the laser processing head onto the back surface of the butt portion of the plate material, thereby obtaining a high-quality weld surface. A method has been proposed (see Patent Document 2 below).

However, the prior art of Patent Document 2 is a back shield method mainly used when welding a plane in a straight line, and a linear groove is brought into close contact with a welding work on the back side of a part to be welded in a linear form. The shield gas is made to flow in the groove. Therefore, in Patent Document 2, there is a problem that it is difficult to adapt to an irradiation processing trajectory having a two-dimensional shape other than a linear shape, in particular, when welding to a round or C-shaped welding trajectory.
JP 2005-177862 A JP 2005-208285 A

  The present invention has been made to solve the above-described problems, and its purpose is to prevent peripheral jigs and equipment from being damaged due to leakage of laser light from the back side of the processing site. Another object of the present invention is to provide a laser processing apparatus and a laser processing method.

  Another object of the present invention is to efficiently cover the back surface of the workpiece processing portion with a shielding gas even when the irradiation processing locus by the laser beam has a two-dimensional shape, thereby obtaining a high-quality laser processing surface. An object of the present invention is to provide a laser processing apparatus and a laser processing method.

  In order to achieve the above object, the present invention provides a laser processing apparatus for performing predetermined laser processing by irradiating a workpiece processing site with a long-focus laser beam, and leaking laser light on the back side of the workpiece processing site. It is characterized in that a light shielding plate is provided for shielding the light. In the laser processing apparatus of the present invention, it is preferable that a side wall directed to the workpiece is provided on the light shielding plate, and a shield gas supply chamber is formed by the light shielding plate and the side wall to surround the back surface of the workpiece processing site.

  According to the present invention, in the laser processing method for performing predetermined laser processing by irradiating a long-focus laser beam to a workpiece processing site, a light shielding plate is provided on the back side of the workpiece processing site, and from the back side of the welding site. It is characterized by blocking the leaked laser beam. In the laser processing method of the present invention, the light shielding plate is provided with a side wall directed to the workpiece, an inert gas is supplied into a shield gas supply chamber formed thereby, and the back surface of the processing portion of the workpiece is covered with the inert gas. However, it is preferable to perform laser processing.

  In the laser processing apparatus and the laser processing method of the present invention, even if the laser beam leaks to the back side at the processing site, it is blocked by the light shielding plate, so that it does not irradiate the gauge post or peripheral device of the jig. It will not be damaged. This effect can be obtained in any laser processing such as welding, drilling, and cutting.

  Further, in the laser processing apparatus and the laser processing method of the present invention, a shield gas supply chamber is formed by the light shielding plate and the side wall, and in order to cover the back surface of the workpiece processing part so as not to be dispersed by supplying an inert gas therein, The shielding effect by the shielding gas can be enhanced. That is, according to the present invention, the concentration unevenness in the atmosphere of the shielding gas is eliminated, and the laser processing quality is improved. For example, in the case of welding, it becomes difficult to attach an oxide film on the back surface of the bead, and the welding quality is improved. In the present invention, since the enclosure is provided by the light shielding plate and the side wall, the flow rate of the shielding gas can be reduced as compared with the case where the shielding gas is simply supplied from the injection nozzle.

  Furthermore, in the laser processing apparatus and the laser processing method of the present invention, since the back side of the processing site is covered by the enclosure composed of the light shielding plate and the side wall, it is possible to eliminate spatter scattering from the back side of the processing site. Further, since the welding bead portion on the back surface of the workpiece can be prevented from being oxidized with a small inert gas flow rate, laser welding can be performed efficiently without deteriorating the adhesion of the coating for the purpose of rust prevention.

  Embodiments according to the present invention will be described below with reference to the drawings.

[First Embodiment]
A laser welding apparatus according to the first embodiment of the present invention is shown in FIG.

As shown in FIG. 1, the laser welding equipment includes a laser oscillator 1 of a YAG laser, a robot hand 2 driven by a 6-axis motor, and an optical head 3 attached to the tip thereof. The head 3 is connected to the laser oscillator 1 by an optical fiber cable, and has a structure in which a long-focus laser beam 5 is emitted from the optical head 3. Further, an optical deflection optical system 4 (scanner) for deflecting the emitting direction of the laser beam 5 is provided inside the optical head 3, whereby the laser beam 5 is scanned along a predetermined welding locus and welded. The pattern is drawn.

The type of laser used here is a YAG laser, but it may be a carbon dioxide laser. An inert gas 39 such as Ar or He can also be used as the assist gas. As a basic welding method, a remote laser welding method capable of instantaneously moving the laser beam 5 will be described below. However, the present invention is applicable to any laser processing apparatus that handles a long-focus laser beam 5A. Therefore, the present invention is not necessarily limited to the remote laser welding method.

  The laser welding equipment also includes clamping means 8 that clamps the two steel plates 7a and 7b serving as the workpieces 6 so as to form a gap.

  As can be seen from FIG. 2, the clamp means 8 includes a lower gauge post 9, a swingable upper clamp member 10, and an air cylinder 11 that drives the clamp member 10. The upper clamp member 10 and the lower gauge post 9 are bent inward so as to face each other in the vertical direction, intersect with each other at their respective corners, and are pivotally connected by a shaft 12. That is, the upper clamp member 10 has an ear 13 near the lower end, and the ear 13 is pivotally attached to the upper corner of the gauge post 9 by the shaft 12. The air cylinder 11 is pivotally attached to the middle of the gauge post 9 by a shaft 14, and the rear end of the piston rod 15 of the air cylinder 11 is pivotally attached to the rear end of the upper clamp member 10 by a shaft 16. . An air hose 17 and a signal cable 18 are connected to the air cylinder 11, and the piston of the air cylinder 11 is operated by air supplied to the inside through the air hose 17.

  With this structure, when the air cylinder 11 is operated, the piston rod 15 is pushed out, the upper clamp member 10 is rotated around the shaft 16, the tip of the clamp member 10 is lowered, and the lower gauge / The workpiece 6 is sandwiched between the posts 9.

  Laser welding is performed by irradiating the two steel plates 7a and 7b of the workpiece 6 thus clamped with the laser beam 5. Each laser welding is performed in a loop shape from a welding start point to a welding end point, and along a welding locus in which the welding start point and the welding end point do not overlap. Examples of welding trajectories that are loop-shaped and in which the welding start point and the welding end point do not overlap are welding trajectories such as a C shape, an S shape, and a round shape. A weld bead is formed. The reason why the welding start point and the welding end point are not overlapped is that if they overlap, they may melt and open holes. Then, when forming such a weld bead, the orientation of the pattern such as a C-shape of the welding trajectory within the welding surface starts with the welding start point of the welding trajectory starting from the smaller gap between the steel plates 7a and 7b. Set as follows. By setting in this way, welding between the steel plates 7a and 7b having a wider gap can be performed as compared to the case where the welding start point of the welding locus is set to start from the larger gap between the steel plates 7a and 7b. It is.

  By the way, a lens having a long focal length is used for remote laser welding, and the laser beam 5 emitted from the optical head 3 has a long focal length of 600 to 1000 mm, for example. For this reason, as shown in FIG. 3 as a comparative example, the laser beam 5A leaks from the back side of the welded portion. When the laser beam 5A leaks, it is damaged by irradiating the gauge post 9 and peripheral devices of the jig.

  As a means for solving this problem, it is conceivable to cover peripheral devices with a protective member. However, in this case, there arises a problem that the operability when maintaining these peripheral devices is deteriorated.

  Therefore, in this embodiment, the laser beam 5A leaked on the back side of the two steel plates 7a and 7b as the workpiece 6, that is, on the back side of the welded portion, as viewed in the irradiation direction of the laser beam 5. A light shielding plate 20 is provided. By providing the light shielding plate 20 in this manner, the laser beam 5A leaking from the back side of the welded portion is not irradiated to the gauge post 9 and peripheral devices of the jig, and the inconvenience of damaging them can be avoided. .

  The light shielding plate 20 is provided apart from the back surface of the workpiece 6. This is because the heat input density of the light shielding plate 20 is reduced by being separated from the focal point of the laser beam 5A.

[Shape of light shielding plate 20]
The form of the light-shielding plate 20 of this invention is shown in FIGS.

  FIG. 4 shows an example of the light shielding plate 20 having a flat surface 21. For the light shielding surface of the light shielding plate 20, a metal material having a heat absorption efficiency of the laser beam 5 </ b> A lower than that of iron is used. For example, copper (laser wavelength 1.06 μm, absorption efficiency 0.05 at room temperature), aluminum (laser wavelength 1.06 μm, absorption efficiency 0.06 at room temperature), or the like is used. In this way, it becomes difficult to absorb the laser light 5A irradiated to the light shielding plate 20, so that the light shielding plate 20 is hardly damaged from the laser light 5A, and the life of the light shielding plate 20 can be extended.

  The light divergence region can be enlarged by bending the surface of the light shielding plate 20 into a convex shape or a concave shape.

  FIG. 5 shows a configuration of the light shielding plate 20 having the convex surface 22. Here, the convex surface 22 is formed in a convex spherical shape. In this way, since the light divergence region is larger than that of the light shielding plate 20 of FIG. 4 having the flat surface 21, the laser light 5A having a high power density irradiated on the light shielding plate 20 can be efficiently diverged. , The jig can be reduced to a power density that is not easily damaged. This effect can also be obtained when the surface of the light shielding plate 20 is bent into a concave shape such as a concave spherical shape.

  The surface of the light shielding plate 20 can irregularly reflect the laser light 5 </ b> A having a high power density irradiated on the light shielding plate 20 by further forming irregularities on the convex or concave surface.

  FIG. 6 shows an example in which the projection surface 22 of the light shielding plate 20, more precisely, the convex spherical surface is provided with a plurality of convex spherical projections 23 having a small radius of curvature, thereby providing irregularities. Is. When such a large number of protrusions 23 are provided, the laser light 5A having a high power density irradiated on the light shielding plate 20 can be radiated more efficiently.

  FIG. 7 shows an example in which the convex surface 22 of the light shielding plate 20 is provided with irregularities by providing a plurality of concave spherical concave portions 24 having a small curvature radius. Even when a large number of recesses 24 are provided in this way, the laser beam 5A can be efficiently diffused as in FIG.

[Second Embodiment]
A second embodiment of the present invention is shown in FIG. This is an example in which the surface of the light shielding plate 20 is finished to be a mirror surface, and the light shielding plate 20 is tilted so that incident light is reflected in a direction having no influence as reflected light 25 as indicated by an arrow. Reflecting in a direction having no influence is, for example, reflecting incident light in a direction in which there is no jig component. According to such a configuration, it is possible to avoid the laser beam 5A leaking from the back side of the welding point from being irradiated to the jig or the component of the jig.

[Third Embodiment]
A third embodiment of the present invention is shown in FIG. This is an example in which a water-cooled laser light absorber 26 that receives and absorbs light reflected by the surface of the light-shielding plate 20 having a mirror finish is disposed. The laser light absorber 26 has a structure in which heat is forcibly discharged by cooling water passing through a cooling pipe 27 provided inside. Therefore, the incident angle and the reflection angle of the light shielding plate 20 provided at each of the plurality of welding sites are adjusted, and the light reflected from each light shielding plate 20 (reflected light 25) is collected in the laser light absorber 26. Thus, the laser beam 5A leaking from the back side of the welding point can be more efficiently reduced to a harmless level.

[Fourth Embodiment]
FIG. 10 shows a fourth embodiment of the present invention in which safety management is automatically performed by the abnormality detection means.

  In this embodiment, the example which laser-welds the several location of the workpiece | work 6 hold | maintained at the jig | tool 31 is shown. A mirror-finished light shielding plate 20 is provided behind each of the plurality of welded portions. By appropriately adjusting the incident angle and the reflection angle of each light shielding plate 20, the light reflected by the light shielding plates 20 is collected in one common laser light absorber 26. In addition, a detector such as a temperature sensor or a photodiode is disposed in the laser light absorber 26 as one component of the abnormality detection means, and the intensity of light received by the laser light absorber 26 is measured. This measured value is guided to the control device 30 in the control panel 29 through the cable 28. The control device 30 is a component of the abnormality detection means, and an abnormality determination means is constructed in hardware or software. When the intensity of the light received by the laser light absorber 26 is higher than a predetermined value in this abnormality determination means, it is determined that there is an abnormality, an abnormality signal is output, and the production line is stopped.

  By providing such an abnormality detection means, it is possible to quickly detect an abnormal state of welding quality or equipment, and to quickly avoid the abnormal state.

[Fifth Embodiment]
FIG. 11 shows a fifth embodiment of the present invention in which the back surface of the welded part is covered with a shielding gas. Also in this embodiment, a light shielding plate 20 for blocking the leaked laser beam 5 </ b> A is provided on the back side of the welded portion of the work 6 so as to be separated from the back surface of the work 6. Reference numeral 32 denotes a stall on the fixed side with respect to the laser beam 5, and a gauge post 9 for positioning is provided at the upper end. Reference numeral 33 denotes a detection sensor for indexing positioning. A signal cable 34 is drawn from the detection sensor 33 and is routed inside the stall 32.

  As described above, the light shielding plate 20 functions to shield the laser beam 5A leaked from the back side of the welded portion, that is, the laser beam 5A that has penetrated, and heat is generated at that time. Therefore, it is preferable to remove the heat generated in the light shielding plate 20. Moreover, it is preferable that the welding bead formed in the back surface and the surface of the said welding site | part is made into a favorable shape so that an oxide film may not be formed on the surface.

  As this means, it is conceivable to perform a back shield by spraying a shield gas directly from the nozzle to the back surface of the welding site. However, in this back shield method, since the shield gas reaches the welded part while entraining the air around the nozzle, it is difficult to cover the back surface of the welded part with the shield gas. That is, since the shielding gas entrains the surrounding air, the shielding effect is lost.

  Therefore, in the fifth embodiment, as shown in FIG. 11, the light shielding plate 20 is provided with a side wall 35 toward the workpiece 6, and the side wall 35 and the light shielding plate 20 provide a back surface of the processing portion of the workpiece 6. A shield gas supply chamber 36 having a shape and a size surrounding is formed.

  In this embodiment, the side wall 35 is integrated with the light shielding plate 20 as shown in FIG. 12A by using a metal material such as copper or aluminum whose heat absorption efficiency of the laser beam 5A is lower than that of iron. It consists of the circular member 35a formed circularly. The diameter of the annular member 35a is large enough to cover the welding site when the annular member 35a is viewed from above, that is, a welding locus of a pattern such as a C-shape drawn by the laser beam 5 in the circle of the annular member 35a. 37 is set to a size. Then, when welding of one welding site in the work 6 is performed, the work 6 or the optical deflection optical system 4 of the optical head 3 is relatively moved to set the laser irradiation scheduled position for welding of the next welding site. Is done. At this time, in the case of a method of moving the clamping means 8 side, the light shielding plate 20 and the side wall 35 are also moved together with the clamping means 8.

  FIG. 12A shows a case where one C-shaped welding locus 37 is placed in the circle of the annular member 35a, but the shape and number of the welding locus 37 are limited to this. is not. That is, a pattern such as a C-shape of the welding locus 37 may exist as a single unit or a plurality of patterns in the circle of the annular member 35a.

  The annular member 35a forming the side wall 35 of the shield gas supply chamber 36 is provided with a shield gas pipe 38 at a connection port communicating with the inside, and an inert gas 39 such as argon, helium or nitrogen is shown through the pipe. Not connected to a gas source. As shown in FIG. 12B, the inert gas 39 introduced from the shield gas pipe 38 into the shield gas supply chamber 36 is surrounded by the light shielding plate 20, the side wall 35, and the back surface of the workpiece, thereby preventing discontinuity. . For this reason, the back surface corresponding to the welded part of the workpiece 6 is sufficiently covered with the shielding gas composed of the inert gas 39.

  Therefore, a sufficient shielding effect of the shielding gas with respect to the back surface of the welded part can be obtained as compared with the case where the shield gas is blown directly onto the back surface of the welded part from the nozzle. That is, since there is no uneven concentration of the shielding gas atmosphere, it is difficult for an oxide film to adhere to the back surface of the bead, and the welding quality is improved. Moreover, the effect that the flow volume of shielding gas can be reduced is acquired. Furthermore, the effect that sputtering can be received in the shield gas supply chamber 36 to prevent diffusion from the back side of the welded part to the surroundings can be obtained.

  Further, since the shield gas supply chamber 36 is installed using the light shielding plate 20, it is not necessary to form the bottom surface of the shield gas supply chamber 36 with a dedicated member. In addition, the fact that the back surface of the work 6 functions as an element forming the upper surface of the shield gas supply chamber 36 is also advantageous in enhancing the shielding effect by the shield gas.

  In the above description, there is at least a gap d between the side wall 35 in the shield gas supply chamber 36 and the back surface of the workpiece 6. For this reason, the inert gas 39 introduced into the shield gas supply chamber 36 from the shield gas pipe 38 fills the shield gas supply chamber 36 and covers the back surface of the welded portion of the work 6, and then the back surface of the work 6. Flows out from the gap d between the two. Therefore, since the inert gas 39 flows on the light shielding plate 20, the heat of the light shielding plate 20 is removed, and the light shielding plate 20 is cooled.

  FIG. 13 shows a form in which the side wall 35 of the shield gas supply chamber 36 is positively separated from the back surface of the work 6 by a gap D. In this way, by forming the gap D between the back surface of the workpiece 6, the side wall 35 can be moved away from the focal point of the laser beam 5 </ b> A. Moreover, since shield gas can be escaped from the clearance gap D between welding workpieces, the effect of cooling the light shielding plate 20 can be obtained.

  The gap D between the back surface and the side wall 35 of the workpiece 6 is specifically 3 mm to 10 mm, and the shielding gas leaks at a rate of 5 to 15 liters per minute per unit area of the opening, that is, 1 mm square. It is set to the size to be. Therefore, welding is performed while leaking 5 to 15 liters of shielding gas per minute from the gap D with the back surface of the workpiece 6.

  The reason why the leaking shielding gas flow rate is set to 5 to 15 liters per minute is that if the shielding gas flow rate is less than 5 liters per minute, the gas pressure at the welded portion is insufficient and an oxide film is formed. This is because if the surface area exceeds 15 liters per minute, the surface of the welded part is disturbed and the occurrence of spatter becomes significant. Therefore, by setting the leakage amount of the shielding gas within the above range, an atmosphere having a stable concentration can be supplied to the welded portion, and stable quality can be ensured. In addition, the shielding gas can be prevented from penetrating through the welding site due to atmospheric pressure.

[Sixth Embodiment]
FIG. 14 shows a sixth embodiment. This is an example in which the light shielding plate 20 on the bottom surface of the shield gas supply chamber 36 is formed as an inclined surface 20 a and an opening 41 for dropping the sputter 40 is provided at the lowermost portion of the side wall 35. The opening 41 can be provided in any shape such as a slit or a hole. FIG. 14 shows an example in which the opening 41 is formed by a slit.

  According to this embodiment, not only can the spatter 40 be received by the shield gas supply chamber 36 to prevent diffusion to the surroundings, but the sputter 40 slides down on the inclined surface 20a and the outside of the shield gas cover is opened from the lower opening 41. Therefore, it is possible to prevent the sputter 40 from being deposited inside the shield gas supply chamber 36.

  FIG. 15 shows a modification. In this case, the light shielding plate 20 on the bottom surface of the shield gas supply chamber 36 is formed in a tapered cone shape as shown as a bottom surface portion 20b in the drawing, and an opening 42 for dropping the sputter 40 is provided at the lowermost portion. It is an example. In the example of FIG. 15A, the upper end of the bottom surface portion 20b is continuous with the same inclination as the side wall portion 35b formed in the same tapered cone shape, and as a whole, a continuous inclined surface 43 having the same angle. Is formed. However, the bottom surface portion 20b and the side wall portion 35b do not need to be continuous at the same inclination angle. As shown in FIG. 15B, the inclined side surface portion 20b is not inclined. It is also possible to adopt a form continued to 35a).

[Seventh Embodiment]
FIG. 16 shows a seventh embodiment. In this configuration, a shield gas pipe 38 communicating with the shield gas supply chamber 36 is detachably attached to the connection port 35 b 35 c of the side wall 35 of the shield gas supply chamber 36. As a method of detachably attaching, here, a screw part is formed in the connection port 35b35c provided in the annular member 35a of the side wall 35, while a screw part 44 is provided at the tip of the shield gas pipe 38. The shield gas pipe 38 is screwed onto the side wall 35 by screwing the screw portion 44 into the screw portion 44 of the connection port.

  By configuring the shield gas pipe 38 so as to be detachable as described above, the replacement time when the light shielding plate 20 or the side wall 35 is cleaned or damaged can be shortened.

  In the above embodiment, the case of laser welding has been described as an example. However, the present invention is not limited to this, and can be applied to general laser processing such as welding, drilling, or cutting with a laser beam 5A. .

[Eighth Embodiment]
In the fifth embodiment (FIGS. 11 to 13), the inert gas 39 is supplied into the shield gas supply chamber 36, and the back surface of the processed portion of the workpiece 6 is covered with the inert gas 39. When the pressure of the gas 39 is increased, there is a possibility that a hole (porosity) is generated in the weld bead. This problem is that a cylindrical container 45 (hereinafter simply referred to as a container-like nozzle 45) having an open upper portion composed of the light shielding plate 20 and the side wall 35 forming the shield gas supply chamber 36 is not completely sealed. In other words, this is solved by providing a slight gap D (see FIG. 13) between the back surface of the processed portion of the workpiece 6 and the top of the side wall 35 of the container-like nozzle 45.

  However, as a new problem, when such a gap D is provided, it is necessary to prevent oxygen from flowing from the gap D. For this reason, the inert gas 39 must be continuously ejected from the gap D, and the gas cost is excessively increased.

  The eighth embodiment (FIGS. 17 to 21) and the ninth embodiment (FIGS. 23 to 25) to be described below solve the above-described problem, reduce the flow rate of the inert gas 39, and reduce the cost. It provides means for reducing.

  Among these, in the eighth embodiment, the container-like nozzle 45 is placed in a sealed state with the work 6 for a necessary minimum period, and the inert gas 39 is introduced into the container-like nozzle 45 during this sealed state. It is made to flow in and welding is carried out while covering the back surface of the welded portion with an inert gas atmosphere.

  In the case of this embodiment, it is desirable to keep the container-like nozzle 45 sealed with respect to the work 6 as much as possible. However, in actuality, it is difficult to control the distance between the workpiece 6 and the container-like nozzle 45 to be constant in all the welds. For this reason, a deviation has occurred between the container-like nozzle 45 due to disturbance. In this case, it became clear that it was difficult to maintain the welding quality.

  Therefore, in the eighth embodiment, as shown in FIG. 17, a close contact mechanism 46 is provided at the open end of the container-like nozzle 45 forming the shield gas supply chamber 36, that is, the top of the side wall 35, and the steel plate 7a, The structure is such that it can be in close contact with the back surface of the workpiece 6 made of 7b. Then, the container-like nozzle 45 is placed in a sealed state with the work 6 for a necessary minimum period, and the inert gas 39 is caused to flow into the sealed container-like nozzle 45.

  FIG. 18 is an enlarged cross-sectional view of the container-like nozzle 45. A contact mechanism 46 provided at the top of the container-like nozzle 45 (the top of the side wall 35) is a material having a high elastic modulus for closely attaching the container-like nozzle 45 to the back surface of the work 6 made of the steel plates 7a, 7b. An elastic body 47 made of rubber, for example, is provided between the top of the side wall 35 so as to support the elastic body 47 and elastically urges the elastic body 47 outward in the axial direction at all times. And an urging member 48.

  The elastic body 47 includes a close contact portion 47 a located above the top of the side wall 35 and a skirt portion 47 b that hangs down from the top of the side wall 35 to the outer periphery. The contact portion 47a extends from the top region of the side wall 35 and from the top portion of the side wall 35 to the radially outer region, and the skirt portion 47b hangs from the contact portion 47a in an inverted L-shaped cross section. Is provided.

  The length of the skirt portion 47b of the elastic body 47 is such that the skirt portion 47b of the elastic body 47 reaches the outer periphery of the side wall 35 after covering the biasing member 48 in an uncompressed state on the side. Therefore, the skirt portion 47b of the elastic body 47 serves to hold the urging member 48 on the inner peripheral side of the skirt portion 47b and keep it in a stable state in relation to the urging member 48. In addition, the skirt portion 47b of the elastic body 47 is fitted to the outer periphery of the side wall 35 in relation to the side wall 35, and thus serves to stabilize the posture of the elastic body 47. Furthermore, since the skirt portion 47b of the elastic body 47 is slidably fitted to the outer periphery of the side wall 35, it also serves as a guide when the elastic body 47 moves in the axial direction.

  On the outer periphery of the side wall 35 of the container-like nozzle 45, there is an annular protrusion 49 that runs in the circumferential direction at a position spaced apart from the lower end of the skirt portion 47b of the biasing member 48 in the non-compressed state by a gap g on the lower side in the axial direction. Is provided.

  FIG. 19A shows a state immediately before the work 6 is placed on the upper part of the container-like nozzle 45. The elastic body 47 has a contact portion 47a away from the work 6, and a skirt portion. 47b is away from the annular protrusion 49 of the side wall 35. That is, both the elastic body 47 and the biasing member 48 are in an extended state in which the top and bottom are free.

  As described above, when the elastic body 47 is not in operation before coming into contact with the workpiece 6, the skirt portion 47 b of the elastic body 47 is separated from the annular protrusion 49.

  When the urging member 48 is compared with the elastic body 47, the urging member 48 has a lower elastic modulus than the elastic body 47 and is configured to be softer and more easily deformed than the elastic body 47. The length of the urging member 48 in the axial direction is made substantially equal to the thickness of the contact portion 47a of the elastic body 47 so that the reaction force from the workpiece 6 can be efficiently absorbed. For this reason, when the container-like nozzle 45 is pushed by the workpiece 6, the biasing member 48 is elastically contracted before the elastic body 47, and the elastic body 47 positioned above the biasing member 48 is It moves to the bottom (the light shielding plate 20) side of the nozzle 45.

  Therefore, when a relative positional shift occurs between the workpiece 6 and the container-like nozzle 45 such that the container-like nozzle 45 itself is inclined, the biasing member 48 is weakly compressed on the side wall 35 on the side far from the workpiece 6, and The urging member 48 is strongly compressed on the side wall 35 on the side close to the workpiece 6. That is, the positional deviation is absorbed by the elastic repulsive action of the biasing member 48, and the elastic member is still maintained in close contact.

  FIG. 19B shows a state immediately after the workpiece 6 is installed on the upper part of the container-like nozzle 45.

  In FIG. 19B, the elastic body 47 is pressed downward while being in close contact with the workpiece 6, and moves in a direction approaching the top of the side wall 35 with respect to the container-like nozzle 45. Therefore, the elastic body 47 is in a state where the relative position with respect to the container-like nozzle 45 is contracted and is submerged from the original free position (FIG. 19A). The skirt portion 47 b of the elastic body 47 is in contact with the annular protrusion 49 on the side wall 35 of the container-like nozzle 45.

  As a process up to this state, the work 6 is first installed, and the relative distance between the work 6 and the container-like nozzle 45 is reduced. Thereby, the biasing member 48 is elastically shortened in the vertical direction and is in a shortened state. Accordingly, the skirt portion 47 b of the elastic body 47 approaches and comes into contact with the annular protrusion 49 provided on the outer periphery of the side wall 35 of the container-like nozzle 45, and receives a repulsive force in the push-up direction from the annular protrusion 49. As a result, the elastic body 47 is pressed from both the upper and lower directions and comes into close contact with the workpiece 6.

  FIG. 20 is a time chart showing a welding method using the container-like nozzle 45 provided with the contact mechanism 46. FIG. 21 shows the appearance of the container-like nozzle 45 used in this embodiment. The container-like nozzle 45 is composed of a cylindrical container with a bottom having an inner diameter of D1 and an axial length of L1, and is inert at the bottom of the container. A supply port 45a for the gas 39 is provided, and a shield gas pipe 38 is connected thereto.

  In the eighth embodiment, the container-like nozzle 45 having the above structure is used, and argon gas is used as a shielding gas having a specific gravity larger than that of air. And the timing which this container-shaped nozzle 45 is closely_contact | adhered to the back surface of the workpiece | work 6 is controlled as shown in FIG.

  First, in order to replace the air in the container-like nozzle 45 with argon, the argon gas flows into the container-like nozzle 45 by an amount substantially equal to the volume of the container-like nozzle 45 at times t1 to t2 (section a in FIG. 20). Let Since the argon gas is a shield gas having a specific gravity greater than that of air, the argon gas stays in the shield gas supply chamber 36 in the container-like nozzle 45.

  Here, the time length of the section a into which the argon gas is introduced varies depending on the volume of the container-like nozzle 45 and the flow rate per unit time. In the present embodiment, a cylindrical container (FIG. 21) having an inner diameter D1 of φ8 to 27 mm and a length L of 45 mm is used as the container-like nozzle 45. In order to fill the container-like nozzle 45 having this volume, 0.002-0.026 liters of argon gas is required. Therefore, assuming that the argon gas reaches the container nozzle 45 as soon as the argon gas release valve is opened, the argon gas is controlled to flow in for 2 seconds (2S) at a flow rate of 1 liter / min. .

  Next, at time t <b> 2 to t <b> 3 (section b in FIG. 20), the steel plates 7 a and 7 b of the workpiece 6 are placed on the jig, and the steel plates 7 a and 7 b of the workpiece 6 are positioned on the shield gas supply chamber 36. At this time, the rubber of the elastic body 47 attached to the container-like nozzle 45 comes into contact with the workpiece 6 and is pressed toward the workpiece 6 by the urging member 48 from behind. The container-like nozzle 45 is in close contact with the back surface of the welded portion of the steel plate 7b by the repulsive force of the spring that is the urging member 48 and the elastic force of the rubber that is the elastic body 47. When the relative distance between the container-like nozzle 45 and the work 6 is reduced, the state shown in FIG. 19B is reached.

  Next, at time t3 to t5 (section c in FIG. 20), argon gas is slightly allowed to flow into the container-like nozzle 45 under the above-described close contact state, and this state is maintained for the minimum necessary time. In this section c, since the inflow of argon gas is continued, the back surface of the welded portion of the steel plate 7b of the work 6 is well shielded with argon gas.

  Under this shield state (section c in FIG. 20), the laser beam 5A is output for the required time indicated by times t4 to t5, and laser welding is performed (section d in FIG. 20).

  If it does in this way, supply_amount | feed_rate of argon gas to the container-like nozzle 45 can be suppressed, and oxidation of a weld bead part can be suppressed with a slight flow rate. As a specific example of this embodiment, argon gas is allowed to flow for 1 second (1S) as a section c in FIG. 20 at a flow rate of 2 liters / min in a container-like nozzle 45 having an inner diameter D1 of 27 mm, including during laser welding. When the laser welding time (section d in FIG. 20) was set to 0.3 seconds, oxidation of the weld bead portion could be satisfactorily suppressed.

  FIG. 22 shows a case where, as a comparative example, after the steel plates 7a and 7b of the workpiece 6 are installed, the inert gas 39 is continuously flowed to the container-like nozzle 45, and laser welding is performed in that state. is there. From comparison between FIG. 22 and FIG. 21, it can be seen that the welding method according to the present embodiment (FIG. 21) requires only a small flow rate of flow and is more economical.

  According to the eighth embodiment, the following advantages can be obtained. By the action of the elastic body 47 and the biasing member 48, the container-like nozzle 45 can be in close contact with the workpiece 6 without a gap. As a result, leakage of the inert gas 39 can be reduced. In addition, since the container-like nozzle 45 can be completely sealed so as to cover the weld bead on the back surface, once the inert gas 39 is filled in the nozzle, the oxidation of the weld bead is suppressed to a very small flow rate. Can be achieved. Further, since the oxidation is suppressed with an extremely small flow rate, the pressure in the container-like nozzle 45 does not increase excessively, and the generation of porosity due to this can be suppressed. In addition, the distance between the steel plate 7b of the workpiece 6 and the container-like nozzle 45 can always be kept uniform at a distance of 0 mm (no gap) by the elastic body 47 and the urging member 48. Thereby, even if the installation location of the container-like nozzle 45 is displaced due to disturbance, the welding quality can be restored with a slight adjustment.

[Ninth Embodiment]
In the ninth embodiment, the container-like nozzle 45 is placed in a sealed state with respect to the work 6 for a minimum necessary period, and the gas pressure in the container-like nozzle 45 is adjusted so as not to be higher than a certain level. A shield gas is caused to flow into the nozzle 45, and the back surface of the welded portion is covered with a shield gas atmosphere to perform welding.

  FIG. 23 shows the structure of the container-like nozzle 45 used in this embodiment. The container-like nozzle 45 is different from that shown in FIG. 18 in that a cylindrical member 52 having pores 51 is provided on the side wall 35, and the inert gas 39 is filled into the container-like nozzle 45 from the pores 51. When the gas pressure in the container-like nozzle 45 reaches a predetermined pressure range, a pressure adjusting mechanism 50 that causes the inert gas 39 to flow out is configured.

  By providing the pores 51 in the side wall 35 of the container-like nozzle 45 in this way, the pressure adjusting mechanism 50 that allows the inert gas 39 in the shield gas supply chamber 36 to flow out only under a certain pressure can be configured. Inconvenience of air entering the shield gas supply chamber 36 from the outside is prevented, and the inert gas 39 leaks out of the shield gas supply chamber 36 before the gas pressure in the shield gas supply chamber 36 increases. Can be eliminated.

  FIG. 24 is a time chart showing a welding method using the container-like nozzle 45 provided with the pressure adjusting mechanism 50. FIG. 25 shows the appearance of the container-like nozzle 45 used in the ninth embodiment. A supply port 45a for the inert gas 39 is provided near the bottom of the side wall 35 of the container-like nozzle 45. FIG. The shield gas pipe 38 is connected to this. Further, a backflow prevention valve 53 is provided in the shield gas pipe 38 in the vicinity of the supply port 45a as shown in a cross section in FIG. The inner diameter D1 and the axial length L1 of the container-like nozzle 45 are the same as those in FIG. Although not shown in FIG. 25, a contact mechanism 46 including an elastic body 47 and a biasing member 48 is provided at the tip of the container-like nozzle 45 as shown in FIG. The place where the backflow prevention valve 53 is installed is not limited to the shield gas pipe 38, and can be provided in the middle of the supply port 45a or the piping. However, it is preferably provided in the vicinity of the supply port 45a.

  In the ninth embodiment, the container-like nozzle 45 having the above-described structure is used, and argon gas is used as the inert gas 39. Then, the container-like nozzle 45 is brought into close contact with the back surface of the work 6 to control the inflow of the inert gas 39 as shown in FIG.

  First, the workpiece 6 is set on the jig at times t1 to t2 (section a in FIG. 24) in FIG. At this time, the opening end of the container-like nozzle 45 is placed on the back surface of the work 6 by the action of the rubber of the elastic body 47 attached thereto and the spring of the biasing member 48 that presses the rubber 47 toward the work 6. Adhere closely.

  Next, in order to fill the inside of the container-like nozzle 45 with argon gas, the argon gas is caused to flow in by the volume of the container-like nozzle 45, that is, the volume of the shield gas supply chamber 36 at time t2 to t3 (section b in FIG. 24). . At this time, since there is air in the container-like nozzle 45, the pressure in the container-like nozzle 45 increases. The backflow from the supply port 45 a to the shield gas pipe 38 is not generated by the function of the backflow prevention valve 53. Therefore, it becomes easy to fill the inert gas in the container nozzle. Moreover, the clogging in the shield gas pipe 38 can be suppressed by preventing the gas accompanying the soot and the sputter 40 from flowing backward to the shield gas pipe 38 side.

  When the pressure in the container-like nozzle 45 reaches a certain pressure value, the inert gas 39 escapes from the pores 51 provided in the side wall 35 as the pressure adjusting mechanism 50. Thus, the shield gas supply chamber 36 is filled with the inert gas 39 and maintained at a constant pressure value, that is, a pressure value at which oxidation of the weld bead is suppressed.

  Next, at time t3 to t5 (section c in FIG. 24), the inert gas 39 is slightly allowed to flow into the container-like nozzle 45 under the above-described close contact state. Also at this time, when the pressure in the container-like nozzle 45 is excessively increased, the pressure is reduced by the pressure adjusting mechanism 50 and is maintained at the constant pressure value. The state in which the inert gas 39 is introduced is maintained for a minimum necessary short time. In the section c, since the inflow of the inert gas 39 is continued in this way, the back surface of the welded portion of the steel plate 7b of the workpiece 6 is well shielded by the inert gas 39.

  Under this shield state (section c in FIG. 24), the laser beam 5A is output for the required time indicated by times t4 to t5, and laser welding is performed (section d in FIG. 24).

  In this way, generation of porosity due to excessive pressure in the container-like nozzle 45 is suppressed, and the supply amount of argon gas to the container-like nozzle 45 is suppressed, and oxidation of the weld bead portion is suppressed with a slight flow rate. can do. Therefore, it is possible to prevent deterioration of the welding quality of the weld bead part.

  As a specific example of this embodiment, in a container-like nozzle 45 having an inner diameter D1 of 27 mm, the pore 51 of the pressure adjusting mechanism 50 is 0.5 mm in diameter, and the flow rate is 2 liters / min. Argon gas was introduced only by (2S) to fill the container-like nozzle 45. In addition, at a flow rate of 2 liters / min, the laser was supplied while argon gas was introduced for 1 second (1S) as a section c in FIG. 24 including during laser welding, and the pressure was maintained at 0.1 to 0.25 MPa. When the welding time (section d in FIG. 24) was set to 0.3 seconds, oxidation of the weld bead portion could be satisfactorily suppressed.

  In this embodiment, the pores 51 are provided in the side wall 35 as the pressure adjustment mechanism 50. However, the pressure adjustment mechanism 50 is not limited to the configuration by the pores. A mechanism may be provided that suppresses the occurrence of porosity in the weld bead portion.

  In both the eighth embodiment and the ninth embodiment described above, laser welding is performed while flowing the inert gas 39 into the shield gas supply chamber 36. However, the workpiece 6 is placed on the shield gas supply chamber 36. It is not necessary for the inert gas 39 to flow in during the installation period, and it is sufficient to flow in the inert gas 39 only during the welding execution period in which laser light is output. For this reason, the period during which the inert gas 39 is allowed to flow into the shield gas supply chamber 36 can be shortened, and the flow rate of the inert gas 39 can be reduced to reduce the welding cost.

[Tenth embodiment]
The container-like nozzle 45 is not limited to the above structure. 27 and 28 show the shape of the container-like nozzle 45 that is effective for supplying the inert gas 39 to the weld bead.

  One of them is shown as a tenth embodiment in FIG. In the embodiment of FIG. 27, the light shielding plate 20 on the bottom surface of the shield gas supply chamber 36 is formed in a tapered cone shape with a semicircular cross section and a tapered shape, as shown as a bottom surface portion 20b in the figure. An opening 42 for dropping soot and spatter 40 (see FIG. 15) is provided at the bottom. Further, a cylindrical member 54 having a male screw 54a cut off on the outer periphery is coaxially provided at the lower end of the opening 42, and a cap-shaped storage container 55 having a female screw 55a cut on the inner periphery thereof. And is detachably screwed. A stepped portion 54c is formed on the upper portion of the cylindrical member 54 so as to function as a stopper when the cap-shaped storage container 55 is screwed.

  When the cap-shaped storage container 55 is thus covered, dust such as soot and spatter 40 passes through the hollow portion 54b of the cylindrical member 54 as shown in FIG. It will be collected as garbage 56. Therefore, if the storage container 55 is removed from the cylindrical member 54 as shown in FIG. 28B, the dust 56 in the storage container 55 can be easily removed. Further, since the opening 42 is closed by forming it as a cap-shaped storage container 55, even if the opening 42 is provided at the bottom of the container-like nozzle in order to easily remove the soot and the spatter 40, the opening 42 cannot be removed. It is possible to prevent the active gas from leaking out.

  There are two effects of making the light shielding plate 20 on the bottom surface of the shield gas supply chamber 36 into a conical portion. First, dust such as soot and spatter 40 tends to slide down, and the storage container 55 as a soot pool at the bottom. The second effect is that the inert gas 39 is guided along the ridge or slope of the cone and easily flows upward.

[Eleventh embodiment]
As an eleventh embodiment, FIG. 29 shows the shape of a container-like nozzle 45 effective for supplying an inert gas 39 to a weld bead. This is an example in which an upper surface portion 57 having a large number of through holes 58 with a small diameter is formed in the upper portion of the shield gas supply chamber 36 of the container-like nozzle 45.

  The numerous thin through holes 58 serve to rectify the flow of the inert gas 39 so as to be directed toward the workpiece 6. That is, the flow of the inert gas 39 becomes uniform by passing through the numerous thin through holes 58, and even if a gap is left between the container-like nozzle 45 and the work 6, a simple cylindrical container is used. The effect of suppressing oxidation is obtained as compared with the case of the nozzle.

  The present invention can be generally applied to laser processing such as welding, drilling or cutting with a laser beam.

It is the schematic which showed the laser welding apparatus which concerns on the 1st Embodiment of this invention. It is the perspective view which showed the laser welding apparatus which concerns on the 1st Embodiment of this invention. It is the figure which showed the laser welding apparatus of the comparative example. It is the figure which showed the form of the light-shielding plate with the flat surface of this invention. It is the figure which showed the form of the light-shielding plate with the convex-shaped surface of invention. It is the figure which showed the form which provided many protrusion on the convex surface of the light-shielding plate of this invention. It is the figure which showed the form which provided many recesses in the convex-shaped surface of the light-shielding plate of this invention. It is the schematic which showed the laser welding apparatus which concerns on the 2nd Embodiment of this invention. It is the schematic which showed the laser welding apparatus which concerns on the 3rd Embodiment of this invention. It is the schematic which showed the laser welding apparatus which concerns on the 4th Embodiment of this invention. It is the schematic which showed the laser welding apparatus which concerns on the 5th Embodiment of this invention. 11A and 11B show the relationship between the shield gas supply chamber and the laser welding portion in FIG. 11, wherein FIG. 11A is a diagram illustrating the relationship between the annular member constituting the shield gas supply chamber and the size of the welding locus, and FIG. It is the figure which illustrated the direction of the inert gas introduced in the gas supply chamber. It is the figure which showed the form which spaced apart the side wall of the shield gas supply chamber in FIG. 11 only by the clearance gap D from the back surface of the workpiece | work. It is the schematic which showed the laser welding apparatus which concerns on the 6th Embodiment of this invention. It is the schematic which showed the modification of the form of FIG. It is the schematic which showed the laser welding apparatus which concerns on the 7th Embodiment of this invention. It is the schematic which showed the relationship between the container-like nozzle of the laser welding apparatus which concerns on the 8th Embodiment of this invention, and a workpiece | work. It is sectional drawing which showed the structure of the container-shaped nozzle of FIG. FIG. 18 shows a contact mechanism provided in the container-shaped nozzle of FIG. 17, (a) is a partial cross-sectional view showing a state before placing a work on the container-like nozzle, and (b) shows a state after the contact is made. It is the fragmentary sectional view shown. It is the timing chart which showed the laser welding method which concerns on the 8th Embodiment of this invention. It is the schematic which showed the shape of the container-shaped nozzle used in the 8th Embodiment of this invention. It is the timing chart which showed the laser welding method of the comparative example. It is the schematic which showed the structure of the container-shaped nozzle of the laser welding apparatus which concerns on the 9th Embodiment of this invention. It is the timing chart which showed the laser welding method which concerns on the 9th Embodiment of this invention. It is the schematic which showed the shape of the container-shaped nozzle used in the 9th Embodiment of this invention. It is the figure which showed the structure which attached the backflow prevention valve to the shield gas pipe | tube to a container-like nozzle. It is the schematic which showed the structure of the container-shaped nozzle of the laser welding apparatus which concerns on the 10th Embodiment of this invention. FIG. 27 is a diagram for explaining the lower structure of the container-shaped nozzle of FIG. 27, (a) is a diagram for explaining a state where a cap-shaped storage container is attached to a cylindrical member, and (b) is a cap-shaped nozzle removed from the cylindrical member. It is the figure which showed the storage container. The structure of the container-like nozzle of the laser welding apparatus which concerns on the 11th Embodiment of this invention is shown, (a) is the top view, (b) is a longitudinal stage figure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Robot hand 3 Optical head 4 Optical deflection optical system 5 Laser beam 5A Laser light 6 Work piece 7a, 7b Steel plate 8 Clamp means 9 Gauge post 10 Clamp member 11 Air cylinder 12 Axis 13 Ear part 14 Axis 15 Piston rod 16 Shaft 17 Air hose 18 Signal cable 20 Shading plate,
21 flat surface,
22 convex surface,
23 protrusions,
24 recess,
25 Reflected light,
26 laser light absorber,
27 Cooling pipe,
28 cables,
29 Control panel,
30 control device,
31 jig,
32 stalls,
33 detection sensor,
34 Signal cable,
35 side walls,
35a annular member,
35b side wall,
35c connection port,
36 Shield gas supply room,
37 Welding locus,
38 Shield gas pipe,
39 Inert gas,
40 spatter,
41 opening,
42 opening,
43 Inclined surface,
44 Screw part,
45 Container nozzle,
45a supply port,
46 Adhesion mechanism,
47 elastic body,
47a adhesion part,
47b Skirt part,
48 biasing member,
49 annular projection,
50 pressure adjustment mechanism,
51 pores,
52 cylindrical member,
53 Check valve,
54 cylindrical member,
54a male thread,
55 storage container,
55a Female thread 56 Garbage,
57 upper surface,
58 Through hole.

Claims (33)

In a laser processing apparatus that performs predetermined laser processing by irradiating a long-focus laser beam on a processing portion of a workpiece,
On the back side of the processing part of the workpiece, a light shielding plate for blocking the leaked laser light is provided ,
A laser processing apparatus, wherein the light shielding surface of the light shielding plate is made of a metal material having a heat absorption efficiency lower than that of iron . In a laser processing apparatus that performs predetermined laser processing by irradiating a long-focus laser beam on a processing portion of a workpiece,
On the back side of the processing part of the workpiece, a light shielding plate for blocking the leaked laser light is provided,
The light shielding plate, wherein a, Relais chromatography The processing device that is formed in convex surfaces of the. In a laser processing apparatus that performs predetermined laser processing by irradiating a long-focus laser beam on a processing portion of a workpiece,
On the back side of the processing part of the workpiece, a light shielding plate for blocking the leaked laser light is provided,
The light shielding plate, wherein a, Relais chromatography The processing apparatus that the surface is formed in a concave. The laser processing apparatus according to claim 1, wherein the light shielding plate is separated from a back surface of the workpiece. The laser processing apparatus according to any one of claims 1 to 4, characterized in that the formation of the uneven surface of the light shielding plate. The laser processing apparatus according to claim 5 , wherein the unevenness is configured by a number of protrusions formed on a surface of the light shielding plate . The laser processing apparatus according to claim 5 , wherein the unevenness is configured by a large number of recesses formed on a surface of the light shielding plate. The laser processing apparatus according to any of the surfaces of the light shielding plate mirror-finished, and claims 1, characterized in that tilting the light shielding plate so as to reflect incident light in a direction not affected 7. The laser processing apparatus of claim 8, wherein the light shielding plate digits set the laser light absorption unit for receiving and absorbing the light reflected by the surface of the. 10. The apparatus according to claim 9, further comprising means for detecting the intensity of light received by the laser light absorber, determining that an abnormality occurs when the received light intensity is higher than a predetermined value, and stopping the production line. Laser processing equipment. The side wall which faces the said workpiece | work was provided in the said light-shielding plate, and the shield gas supply chamber surrounding the back surface of the process site | part of the said workpiece | work was formed by the said light-shielding plate and the said side wall, The Claim 1 thru | or 7 characterized by the above-mentioned. Laser processing equipment. The laser processing apparatus according to claim 11 , wherein the side wall is made of a metal material having a heat absorption efficiency lower than that of iron . The laser processing apparatus according to claim 11 , wherein the side wall is separated from the back surface of the workpiece, and a gap for leaking a shielding gas is formed between the side wall and the back surface of the workpiece. 14. The laser processing apparatus according to claim 13 , wherein the size of the gap is such that the shielding gas leaks at a rate of 5 to 15 liters per minute per unit area . The laser processing apparatus according to claim 11 , wherein a light shielding plate on a bottom surface of the shield gas supply chamber is formed as an inclined surface, and an opening for dropping spatter is provided at a lowermost portion of the side wall. . 15. The laser processing apparatus according to claim 11, wherein a light shielding plate on a bottom surface of the shield gas supply chamber is formed in a tapered conical shape, and an opening for dropping spatter is provided at a lowermost portion thereof. . The laser processing apparatus according to claim 11 , wherein a shield gas pipe communicating with the shield gas supply chamber is detachably attached to the side wall . On top of the side wall, the laser processing apparatus according to claim 11 or 12, characterized in that the adhesion mechanism which can contact the open end of the side wall relative to the rear surface of the workpiece digits set. The contact mechanism is provided between an elastic body for closely attaching the open end of the side wall to the back surface of the work without a gap, and a top of the side wall in a form to support the elastic body. The laser processing apparatus according to claim 18 , comprising a biasing member that always biases elastically outward in the axial direction . The elastic body contact mechanism is a rubber, the laser processing apparatus of claim 19, wherein the biasing member is characterized Rukoto such a spring. When the side wall is provided with pores and the gas pressure in the shield gas supply chamber reaches a predetermined pressure range, the inert gas is allowed to flow outside to make the gas pressure in the shield gas supply chamber constant. the laser processing apparatus according to claim 11 or 12 pressure adjustment mechanism is characterized that you have been configured to. The laser processing apparatus according to claim 21 , wherein a backflow prevention valve for preventing a backflow of the inert gas is provided in a pipe for supplying the inert gas to the shield gas supply chamber . Formed conically tapered light shielding plate of the bottom surface of the shielding gas supply chamber, in any one of claims 18 to 21, characterized in that an opening for dropping the dust such as soot or sputtering on the bottom The laser processing apparatus as described. The laser processing apparatus according to claim 23 , wherein a cup-shaped storage container for storing the dust is detachably provided below the opening for dropping the dust . The laser processing apparatus according to any one of claims 1 to 24, wherein the predetermined laser processing is any one of welding, drilling, and cutting . In a laser processing method of performing predetermined laser processing by irradiating a long-focus laser beam to a processing site of a workpiece,
Provide a light-shielding plate on the back side of the processing part of the workpiece, to block the laser light leaked from the back side of the welding part
A laser processing method, wherein a metal material having a heat absorption efficiency lower than that of iron is used as a material of the light shielding plate. 27. The laser processing method according to claim 26, wherein the light shielding plate is spaced apart from the back surface of the workpiece and away from the focal point of the laser beam . The side wall toward the workpiece to the light shielding plate is provided, thereby supplying an inert gas to the shielding gas supply chamber formed, characterized that you laser processing while covering the rear surface of the machined portion of the workpiece with an inert gas The laser processing method according to claim 26 or 27 . Laser processing method according to claim 28 said sidewalls said is spaced from the rear surface of the workpiece to form a gap, to laser processing to said Rukoto while leaking shielding gas from the gap. 30. The laser processing method according to claim 29 , wherein laser processing is performed while leaking 5 to 15 liters of shielding gas per minute per unit area from the gap . A side wall facing the workpiece is provided on the light shielding plate to form a shield gas supply chamber, and the side
Compared to air, the shield gas supply chamber has a work adhesion mechanism at the top of the wall.
A process in which a heavy shielding gas is allowed to flow and stay approximately by volume; and
Next, the workpiece is positioned on the shield gas supply chamber, and the tip of the side wall is placed on the contact machine.
Close contact with the back surface of the workpiece through the structure, and sealing the shield gas supply chamber;
Laser light is irradiated while shielding gas flows into the sealed shielding gas supply chamber.
Laser processing method of claim 30 that has a step, and characterized in that. A shield gas supply provided with a pressure adjusting mechanism for stabilizing the internal gas pressure while providing a shield gas supply chamber at the top of the side wall by providing a side wall facing the workpiece on the light shielding plate. A work is positioned on the open end side of the chamber, the tip of the side wall is brought into close contact with the back surface of the work via the contact mechanism, and the shield gas supply chamber is sealed,
Filling an inert gas into the sealed gas supply chamber in the sealed state by flowing an inert gas substantially by a volume; and
Irradiating the workpiece with laser light while allowing the inert gas to flow into the shield gas supply chamber filled with the inert gas and maintaining a constant internal gas pressure by the pressure adjusting mechanism, The laser processing method according to claim 26 or 27 , wherein: As the material of the side wall, the laser processing method according to any one of claims 26 to 32 heat absorption efficiency is characterized Rukoto with low metal material than at least iron.

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