JP4352920B2 - Laser processing head and laser processing method - Google Patents

Description

  The present invention relates to an improvement in a laser processing head and a laser processing method for various processes represented by laser welding, for example, using MIG welding or TIG welding, which is one of laser welding and inert gas arc welding, in combination. More specifically, the present invention relates to a laser processing head and a laser processing method for preventing adhesion of spatter and fumes, which are welding by-products, to a laser optical system.

  In so-called hybrid welding in which laser welding and MIG welding are used in addition to laser welding, a protective glass is provided between the laser optical system and the welding position, and in many cases the front side of the final condenser lens (focal lens). In general, measures are taken to prevent damage to the laser optical system due to adhesion of spatter and fumes (hereinafter referred to as spatter) as welding by-products.

  However, even if the condensing lens and the like can be protected, adhesion of spatter and the like to the protective glass itself is also unavoidable. The cost will be increased due to the increase in the frequency of replacement, and the productivity will be reduced. In particular, in the welding of galvanized steel sheets and aluminum-based materials, the above tendency becomes more prominent because of the large amount of spatter generated.

Therefore, as described in Patent Document 1, an air flow that is substantially parallel to the plane of the welded portion is actively generated between the protective glass that protects the laser optical system and the welded portion, so-called an air shutter. A device having a function has been proposed.
JP 2000-263276 A (FIG. 1)

  However, in the technique described in Patent Document 1, as a special feature of the air shutter, it is impossible to blow off all the sputters in a predetermined direction, and there is still room for improvement.

  More specifically, in the technique described in Patent Document 1, since the function as an air shutter is provided in the protective cylinder arranged on the front side of the protective glass, the kinetic energy of the compressed air efficiently acts on sputtering and the like. However, spatter scattered on the upstream side of the air flow is likely to adhere to the protective glass, and a negative pressure is generated below it due to the secondary action of the air shutter, and the inert gas supplied around the processing site The flow becomes unstable and there is still concern about the effect on welding quality due to the lack of the so-called shielding effect.

  The present invention has been made paying attention to such a problem, and in laser processing represented by so-called hybrid welding, spatter that is a welding by-product to protective glass protecting the laser optical system, etc. The present invention provides a laser processing head and a laser processing method that prevent the occurrence of secondary defects due to an air shutter, while further suppressing the adhesion of the toner.

  The invention according to claim 1 irradiates a workpiece with laser light from a laser optical system disposed above the workpiece, and in a space formed by a laser beam irradiation port of the laser optical system and the workpiece, A first air shutter is formed with a flow of air substantially parallel to the workpiece, and the scattering direction of the machining by-product is deflected by the first air shutter so that the machining by-product adheres to the laser optical system. It is assumed that the laser processing head is designed to perform processing while suppressing the above.

In addition, the optical axis of the laser beam is tilted with respect to the workpiece, while being substantially parallel to the workpiece so as not to interfere with the laser beam in the space formed by the laser beam irradiation port of the laser optical system and the workpiece. A protective cylinder is arranged to form a first air shutter in the protective cylinder, and an air intake opening is formed in a side surface of the protective cylinder, and further intersecting with the first air shutter. The second air shutter is formed with an air flow directed obliquely downward from above the protective cylinder, and the scattering direction of the machining by-product is deflected by a synergistic effect of the first and second air shutters. It is characterized by that.

  In this case, in order to incline the optical axis of the laser beam with respect to the workpiece, the angle formed by the processing direction and the optical axis of the laser beam on the processing progress direction side is an acute angle as described in claim 2. The laser optical system is tilted as described above, and at the same time, the second air shutter is formed with a flow of air directed obliquely downward from above the protective cylinder toward the processing progress direction while intersecting with the first air shutter. And

  According to a third aspect of the present invention, an optical path hole through which the laser beam passes is formed in the protective cylinder, and air from the second air shutter is introduced into the protective cylinder from the optical path hole on the upper side of the protective cylinder. It is desirable that a flow be introduced.

Further, as described in claim 4, it is desirable that protective glass for protecting the laser optical system from adhesion of processing by-products is disposed on the front surface of the laser beam irradiation port in the laser optical system.

The invention described in claim 6 captures the technique described in claim 1 as a laser processing method, and irradiates a workpiece with a laser beam from a laser optical system disposed above the workpiece. A first air shutter is formed with a flow of air substantially parallel to the workpiece in a space formed by the laser beam irradiation port of the laser optical system and the workpiece, and a processing by-product is formed by the first air shutter. It is premised that the laser processing method is to perform processing while deflecting the scattering direction of the laser beam and suppressing adhesion of processing by-products to the laser optical system.

Then, the laser optical system is tilted so that the angle formed by the processing direction and the optical axis of the laser beam on the processing progress direction side is an acute angle, while the laser light irradiation port of the laser optical system and the workpiece are formed. A protective cylinder that is substantially parallel to the workpiece is arranged in the space so as not to interfere with the laser beam, and a first air shutter is formed in the protective cylinder, and an air intake port is provided on the side of the protective cylinder. An opening is formed, and further, a second air shutter is formed with a flow of air directed obliquely downward from above the protective cylinder toward the processing progress direction while intersecting with the first air shutter. The scattering direction of the processing by-product is deflected with a synergistic effect of the air shutter of No. 2.

The laser processing described in claims 1 and 6 includes not only the most typical laser welding but also hybrid welding performed by using both laser welding and arc welding.

Therefore, according to the first and sixth aspects of the present invention, the laser optical system is formed by the amount of inclination of the optical axis of the laser beam as compared with the case where the optical axis of the laser beam and the workpiece are facing each other. Spatter or the like is difficult to adhere to the lens and the protective glass.

  In addition to the first air shutter, the slanted second air shutter is used in combination, so that the effect of deflecting the scattering direction of spatter and the like is increased, and the spatter and the like directed in the direction of the laser optical system is greatly reduced. It becomes possible to make it.

  Even if a negative pressure is generated as a secondary action of the first air shutter, the air corresponding to the negative pressure is supplemented by the second air shutter, so that the air flow inside and outside the protective cylinder is stabilized. Even when an inert gas is supplied around the processing site so as to use an inert gas for shielding, the shielding effect by the inert gas is not insufficient as in the prior art.

According to the first and sixth aspects of the invention, the laser optical system or the protective glass protecting the laser optical system can be sputtered by using the inclined posture of the laser optical system and using the first and second air shutters together. Adhesion is greatly suppressed, welding quality is improved, and man-hours can be reduced and productivity can be improved by reducing the replacement frequency of the protective glass.

  In addition, the combined use of the first and second air shutters stabilizes the air flow inside and outside the protective cylinder, so that it is possible to prevent secondary problems from occurring due to negative pressure generation as in the prior art.

  FIG. 1 shows the structure of the main part of a laser welding head as a more specific embodiment of the present invention.

  In FIG. 1, W is a flat plate-shaped workpiece (workpiece) made of, for example, an aluminum-based material, 1 is a laser welding head as a laser processing head, and 2 is an inert gas arc welding disposed in proximity to the laser welding head 1. This is a torch for MIG welding.

Laser light L such as a YAG laser output from a laser oscillator (not shown) is introduced into the housing 3 of the laser welding head 1 and a laser optical system is formed together with a collimation lens (not shown). The condensing lens 4 to be accommodated is accommodated and disposed, and the condensing lens 4 is disposed on the front side of the laser beam irradiation port 5 facing the condensing lens 4, that is, closer to the workpiece W than the laser beam irradiation port 5. A fixed protective glass 6 is provided for protection. Therefore, the laser beam L introduced into the housing 3 is condensed by the condenser lens 4 and then irradiated to the processing portion P on the workpiece W with a predetermined spot diameter.

  Here, as is apparent from FIG. 1, the axis of the housing 3 containing the laser optical system, that is, the optical axis B of the laser beam L is not perpendicular to the workpiece W, and the welding direction and the laser beam L Laser optics so that the angle θ between the perpendicular line O to the workpiece W and the optical axis B of the laser beam L is about 10 °, for example, so that the angle formed with the optical axis B on the processing progress direction side is an acute angle. The system is tilted.

  For example, when the workpiece W is a fixed side and the laser welding head 1 and the MIG welding torch 2 are movable, the laser welding head 1 and the MIG welding torch 2 are moved integrally at a predetermined speed in the welding direction. Thus, welding is performed on the irradiated portion B of the laser beam L on the workpiece W, and at the same time, MIG welding is performed so as to follow the laser welded portion B. In addition, the code | symbol S of the figure shows the sputter | spatter etc. which are welding by-products (processing by-products) by which the generation | occurrence | production and scattering are unavoidable in the case of welding.

  In the space formed by the workpiece W and the laser beam irradiation port 5, a protective cylinder 7 having a hollow rectangular tube shape is disposed so as to be substantially parallel to the workpiece W as shown in FIG. The protective cylinder 7 can be moved integrally while maintaining the relative positional relationship of FIG. 1 with respect to the laser welding head 1, and the laser light according to the degree of inclination of the optical axis B of the laser light L. Circular optical path holes 8 and 9 for allowing the passage of the laser light L without interfering with L are formed vertically.

  A first air shutter 10 is provided in the protective cylinder 7 so as to be directed in the horizontal direction, that is, in a direction substantially parallel to the work piece W, and a second air shutter 10 is directed obliquely downward above the protective cylinder 7. An air shutter 11 is provided.

  The first air shutter 10 blows out compressed air in layers along the inner surface of the bottom plate 7 </ b> A of the protective cylinder 7 from the flat air blow nozzle 12 arranged close to the protective cylinder 7, and extends along the longitudinal direction of the protective cylinder 7. Thus, the air flow 13 is generated, and the function as the first air shutter 10 is exhibited by this flow 13.

  On the other hand, the second air shutter 11 blows out compressed air from the air blow nozzle 14 disposed obliquely at a position close to the laser beam irradiation port 5 of the housing 3 toward the upper optical path hole 8. An air flow 15 having a substantially circular cross section that is directed obliquely downward from the upstream side of the protective cylinder 7 toward the welding progress direction while intersecting with the air flow 13 by the first air shutter 10, With this air flow 15, the function as the second air shutter 11 is exhibited. In the upper optical path hole 8 through which the air flow 15 by the second air shutter 11 passes, the nozzle diameter of the air blow nozzle 14 is set so that the air flow 15 occupies almost the entire opening area. It is set in advance.

  As is apparent from FIG. 2, a rectangular air intake 16 is formed in the upper part of the side plates 7b, 7b on both sides of the protective cylinder 7 along the longitudinal direction thereof. When the negative pressure suction action by the air shutter 10 occurs, it is considered that outside air can be actively sucked from the side portion of the protective cylinder 7. The position of the air intake 16 is preferably provided at a position that is about one-half or one-third of the height of the protective cylinder 7 from the upper end.

  The air blow nozzles 12 and 14 of the first and second air shutters 10 and 11 in addition to the protective cylinder 7 may be integrated with the housing 3 of the laser welding head 1 or separate from each other. It is sufficient that the laser welding head 1 and the laser welding head 1 can move in synchronization with the welding direction.

  According to the laser welding head 1 configured as described above, the laser welding head 1 and the MIG torch 2 are integrally moved with respect to the workpiece W, and laser light is directed from the laser welding head 1 toward the welding site P. While irradiating L, a welding wire (not shown) that functions as a melting electrode is fed out from the tip of the MIG welding torch 2 and an arc is generated between the welding wire and the work W to be welded. The laser welding and MIG welding are used in combination so as to follow the light irradiation site, and so-called hybrid welding is performed as in the conventional case.

  At the same time, in parallel with the welding operation, compressed air is jetted from the air blow nozzles 12 and 14 so that the functions as the first and second air shutters 10 and 11 are exhibited.

  As the welding operation proceeds, spatter S or the like scatters from the welded part P, and a part of the spatter S or the like deviating from the optical path of the laser beam L adheres to the protective cylinder 7 and is removed. Spatter S scattered in the direction, that is, spatter S entering the protective cylinder 7 through the lower optical path hole 9 is deflected by the air flow 13 of the first air shutter 10 and blown in the downstream direction. However, some of them pass through the first air shutter 10 and scatter further upward. On the sputter S and the like that penetrates the first air shutter 10, the flow 15 of the second air shutter 11 acts obliquely downward above it to deflect the scattering direction. It will be blown away downstream.

  Thus, although the first and second air shutters 10 and 11 are used in combination, a large amount of spatter S or the like is blown away in the protective cylinder 7 in the downstream direction. Through the air shutters 10 and 11 of 1 and 2, the protective glass 6 is reached. Then, a part of the spatter S or the like rebounds and falls on the protective glass 6, and a very small part of the sputter S or the like that remains adheres to the protective glass 6.

  On the other hand, a flow field 17 directed in the same direction as the flow of the first air shutter 10 is generated due to the combined action of the first and second air shutters 10 and 11 inside and outside the protective cylinder 7. This flow field 17 generates a negative pressure inside the protective cylinder 7 and further promotes the introduction of the air flow 15 of the second air shutter 11 from the upper optical path hole 8 in the protective cylinder 7. This facilitates the intake of air from the air intakes 16 on both sides. Thereby, the negative pressure generated by the influence of the flow field 17 can be supplemented by the introduction of air from the upper optical path hole 8 and the air intake port 16. As a result, the pressure inside and outside the protective cylinder 7 is balanced, and inflow of air from the lower optical path hole 9 in the protective cylinder 7 can be suppressed. This means that the flow of the inert gas is not disturbed when welding is performed while supplying the inert gas toward the periphery of the weld site P, and a sufficient shielding effect is obtained by the combined use of the inert gas. This will contribute to the improvement of welding quality.

  As described above, according to the present embodiment, in combination with the inclination of the laser welding head 1 itself, the adhesion of the sputter S or the like to the protective glass 6 protecting the laser optical system is minimized. In addition to improving the welding quality, it is possible to contribute to a reduction in the replacement frequency of the protective glass & an improvement in productivity.

  3 and 4 are views showing modifications of the protective cylinder 7 as the second and third embodiments of the present invention.

  In the second embodiment shown in FIG. 3, the air intake ports 26 to be formed on the side plates 7 b and 7 b on both sides of the protective cylinder 7 are set at positions close to the inlet side of the protective cylinder 7. .

  In the second embodiment, there is an advantage that the intake of air on the inlet side of the protective cylinder 7 is further promoted and the inflow of air from the lower optical path hole 9 can be further suppressed.

  Further, in the second embodiment shown in FIG. 4, the air intake ports 36 to be formed in the side plates 7b, 7b on both sides of the protective cylinder 7 are those shown in FIG. 2 and those shown in FIG. Thus, the same effect as that of the second embodiment can be obtained.

The principal part cross-section explanatory drawing at the time of applying to a laser welding head as more concrete embodiment of this invention. The perspective view which shows the detail of the protection cylinder in FIG. The perspective view which shows the modification of the protection cylinder shown in FIG. 1 as the 2nd Embodiment of this invention. The perspective view which shows another modification of the protection cylinder shown in FIG. 1 as the 3rd Embodiment of this invention.

Explanation of symbols

1. Laser welding head (laser machining head)
2 ... MIG welding torch (welding torch for arc welding)
3 ... Housing 4 ... Condensing lens (laser optical system)
DESCRIPTION OF SYMBOLS 5 ... Laser beam irradiation opening 6 ... Protection glass 7 ... Protection cylinder 8, 9 ... Optical path hole 10 ... 1st air shutter 11 ... 2nd air shutter 12, 14 ... Air blow nozzle 13, 15 ... Air flow 16 ... Air Inlet L ... Laser beam P ... Welding part (processing part)
S: Spatter (welding by-product or processing by-product)
W ... Workpiece (workpiece)

Claims (7)

While irradiating a laser beam from a laser optical system disposed above the workpiece,
A first air shutter is formed in the space formed by the laser beam irradiation port of the laser optical system and the workpiece with an air flow substantially parallel to the workpiece,
A laser processing head that performs processing while deflecting the scattering direction of processing by-products by the first air shutter and suppressing adhesion of processing by-products to the laser optical system,
While tilting the optical axis of the laser beam with respect to the workpiece,
A protective cylinder that is substantially parallel to the workpiece is arranged in the space formed by the laser beam irradiation port of the laser optical system and the workpiece so as not to interfere with the laser beam, and the first air shutter is placed in the protective cylinder. And forming an air intake opening on the side of the protective cylinder,
Furthermore, a second air shutter is formed with a flow of air directed obliquely downward from above the protective cylinder while intersecting with the first air shutter,
A laser processing head characterized in that the scattering direction of processing by-products is deflected by a synergistic effect of the first and second air shutters. In order to incline the optical axis of the laser beam with respect to the workpiece, the laser optical system is inclined so that the angle formed by the processing direction and the optical axis of the laser beam is an acute angle,
2. The laser according to claim 1, wherein the second air shutter is formed with a flow of air that is directed obliquely downward from above the protective cylinder toward the processing progress direction while intersecting with the first air shutter. Processing head. An optical path hole through which the laser beam passes is formed in the protective cylinder,
3. The laser processing head according to claim 1, wherein a flow of air by the second air shutter is introduced into the protective cylinder from an optical path hole on the upper side of the protective cylinder. The laser according to any one of claims 1 to 3, wherein a protective glass for protecting the laser optical system from adhesion of processing by-products is disposed on the front surface of the laser light irradiation port in the laser optical system. Processing head. Processing for the workpiece is
The laser welding head is a hybrid welding in which welding is performed by using laser welding and arc welding together while moving the laser machining head relative to the workpiece together with a welding torch for arc welding arranged close thereto. The laser processing head according to any one of 1 to 4. While irradiating a laser beam from a laser optical system disposed above the workpiece,
A first air shutter is formed in the space formed by the laser beam irradiation port of the laser optical system and the workpiece with an air flow substantially parallel to the workpiece,
A laser processing method that performs processing while deflecting the scattering direction of processing by-products by the first air shutter and suppressing adhesion of processing by-products to the laser optical system,
While tilting the laser optical system so that the angle formed by the processing direction and the optical axis of the laser beam on the processing progress direction side is an acute angle,
A protective cylinder that is substantially parallel to the workpiece is arranged in the space formed by the laser beam irradiation port of the laser optical system and the workpiece so as not to interfere with the laser beam, and the first air shutter is placed in the protective cylinder. And forming an air intake opening on the side of the protective cylinder,
Further, a second air shutter is formed with a flow of air directed obliquely downward from above the protective cylinder toward the processing progress direction while intersecting with the first air shutter,
A laser processing method characterized by deflecting the scattering direction of processing by-products with a synergistic effect of the first and second air shutters. Laser processing method according to claim 6 which process against the workpiece, characterized in that it is a hybrid welding performed using both the laser welding and arc welding.

Images