JP2014128832A - Apparatus and method for laser welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of laser welding executed in a reduced-pressure environment that welding plume severely rising right upward adheres to machinery present over the execution part and disturbs stable laser welding for long a time.SOLUTION: In a laser welding apparatus, the inside pressure of a welding chamber 20 composed of a housing 21 is reduced to a pressure lower than the atmospheric pressure, and a to-be-welded object 1 is irradiated with a laser beam 3 in the reduced-pressure atmosphere to execute welding. An aerodynamic window is created with an ultrasonic gas flow in the laser beam irradiation port 12 of the welding chamber 20 to retain a differential pressure between the atmosphere and the welding chamber 20, and the housing 21 and the to-be-welded object 1 are moved relatively.

Description

  The present invention relates to a laser welding apparatus and a laser welding method performed under a reduced pressure environment.

  Compared with the arc welding method, the laser welding method has the advantage that non-contact welding can be applied to the work piece and that a high energy density beam can be concentrated, resulting in deep penetration. is there. Further, since deep penetration can be obtained with a low heat input as compared with arc welding, there is an advantage that the deformation amount of the workpiece is small and the thermal influence on the workpiece is small. Since the laser welding method has such advantages, its application is expanding at the manufacturing site of industrial equipment. For example, application is progressing in many fields, represented by the electric power equipment, shipbuilding, and automobile fields.

  Laser welding can be broadly classified into a construction method performed under a normal pressure environment (also referred to as an atmospheric pressure environment) and a construction method performed under a reduced pressure environment, depending on the construction atmosphere. Usually, a laser welding method is generally performed while spraying a shielding gas under a normal pressure environment.

  Laser welding under a reduced pressure environment has an advantage that a deeper penetration depth can be obtained when welding is performed with the same heat input as compared with laser welding under a normal pressure environment. One of the factors is that, under a reduced pressure environment, generation of keyholes made of metal vapor that contributes to an increase in the penetration depth is promoted by a decrease in the vapor pressure of the metal due to the reduced pressure atmosphere. Another factor is a decrease in the amount of scattered laser light due to refraction of the laser light as compared to an atmospheric pressure atmosphere.

  In general, when there is a large density difference in the construction atmosphere in which laser light is transmitted, the laser light is refracted, resulting in a decrease in energy reaching the processing point. Therefore, when the amount of heat transferred from the welded part to the gas in the construction atmosphere increases, a part where the density difference of the gas in the construction atmosphere increases locally, and the part where the refraction of laser light in the gas in the construction atmosphere increases Is likely to occur.

  However, under a reduced pressure environment, since the gas in the construction atmosphere is small in the first place, the density difference between the atmosphere gases becomes small, the laser light is hardly refracted, and the energy of the laser light reaching the processing point increases. Laser welding in a reduced pressure environment that can increase the penetration depth due to these factors, but unlike welding in a normal pressure environment, the welding plume rises vigorously right above because the atmospheric pressure is low. As a result, there is a problem that a laser beam irradiation window generally made of a solid material becomes dirty, and long-time continuous welding is difficult.

  Several improvement techniques have been proposed for this problem. As a first improvement technique, a cylindrical nozzle having a projection-shaped portion on the inner surface is provided in a laser beam irradiation window facing the welding chamber, and a gas flowing downward is flowed into the cylindrical nozzle. There is a technology that prevents the rise of the welding plume and reduces the adverse effects of the welding plume.

This technique is considered to be effective to some extent under laser power conditions where a relatively small amount of welding plume is generated, that is, a heat input is small.
As a second improvement technique, there is a technique in which an aerodynamic window (aerodynamic window) is generated in the center of the ceiling of the welding chamber.

  This aerodynamic window is provided with an upper vacuum chamber having an upper nozzle and a lower nozzle at the center of the ceiling of the welding chamber, and further, a lower ejector for ejecting compressed gas from the upper vacuum chamber side of the upper nozzle to the atmosphere side is provided. At the same time, an upper ejector for ejecting compressed gas is provided further above the upper nozzle.

JP-A-7-68397 JP 2011-240365 A Japanese Examined Patent Publication No. 2-42308

  However, in the first improvement technique described above, when the amount of heat input aiming at an increase in the penetration depth is large, the welding plume that is generated in large quantities cannot be discharged sufficiently, so that the welding torch, optical instrument, etc. There is a possibility that welding plume may adhere and continuous welding work for a long time cannot be performed.

  In the case of the second improvement technique described above, the aerodynamic window is provided with an upper vacuum chamber having an upper nozzle and a lower nozzle in the center of the ceiling of the vacuum welding chamber, and further from the upper vacuum chamber side of the upper nozzle to the atmosphere side. The lower ejector that ejects the compressed gas toward the upper nozzle and the upper ejector that ejects the compressed gas to the upper part of the upper nozzle are not only complicated, but also structurally the atmosphere and the vacuum welding chamber It is thought that the pressure difference cannot be maintained. If the pressure difference between the atmosphere and the vacuum welding chamber cannot be maintained by the aerodynamic window, there is a concern that the laser light is scattered and adversely affects the welding quality.

  Furthermore, since both the first and second improvement techniques described above are not particularly provided with a carry-in / out port for carrying in / out the work piece in the welding chamber, the work piece is carried into the welding chamber. Or it takes time to carry it out after welding, and there is a problem that the efficiency of welding work is poor.

  Accordingly, an object of the present invention is to improve the aerodynamic window, thereby maintaining the differential pressure between the atmospheric pressure and the pressure in the welding chamber constituting the reduced pressure environment, and reliably discharging the welding plume in the welding chamber. It is an object of the present invention to provide a laser welding apparatus and a laser welding method capable of continuously performing laser welding for a long time.

  Another object of the present invention is to improve the aerodynamic window to maintain the differential pressure between the atmospheric pressure and the pressure in the welding chamber that constitutes the reduced pressure environment, and to reliably discharge the welding plume in the welding chamber. Laser welding is designed to improve the efficiency of welding work by providing an opening for loading and unloading workpieces in the welding chamber, while enabling continuous laser welding work for a long time. It is to provide an apparatus and a laser welding method.

  In order to achieve the above object, the laser welding apparatus of the present invention is formed in a cylindrical shape, one end is closed except for the laser light irradiation window, and the other end is an open end. A casing that forms a welding chamber by attaching a seal member to a work piece or welding work floor and a top position of the laser light irradiation window are fixed, and a free vortex aerodynamic window is generated by supersonic gas flow An aerodynamic window generating device that aerodynamically partitions the inside of the welding chamber and the atmosphere by the free vortex aerodynamic window, a laser processing head installed at an upper position of the aerodynamic window generating device, and the welding chamber It is characterized by comprising: a decompression device that places the interior in a decompressed environment state from atmospheric pressure; and a device that relatively moves the casing and the workpiece.

  The laser welding apparatus according to the present invention is the laser welding apparatus according to claim 1, wherein the casing houses the workpiece to be welded and a work table on which the workpiece to be welded is placed inside the welding chamber, and the side to be welded is the workpiece. A loading / unloading port for the workpiece and the processing table, and a closing device for opening and closing the loading / unloading port, and the open end is in contact with and fixed to the welding work floor via the sealing material. .

  According to the present invention, the aerodynamic window is generated by the supersonic gas flow flowing from the nozzle of the aerodynamic window generating device provided at the laser beam irradiation port of the welding chamber in a decompression environment to the violently rising from the welding portion. A laser that provides a stable and deep penetration depth in a reduced pressure environment because the welding plume can be reliably ejected by supersonic gas flow and at the same time maintain the differential pressure between the welding chambers in atmospheric and reduced pressure environments. Welding can be performed stably for a long time.

  Furthermore, according to the present invention, since the carry-in / out port for the workpiece is provided in the welding chamber and the carry-in / out port is opened and closed by the closing device, the efficiency of the welding operation can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the principal part of the laser welding apparatus which concerns on Embodiment 1 of this invention, FIG.1 (a) is sectional drawing which cut | disconnected FIG.1 (b) by the aa line and looked at the arrow direction, figure 1 (b) is a cross-sectional view of FIG. 1 (a) taken along line bb and viewed in the direction of the arrows. The principle explanatory drawing of an aerodynamic window. The figure which shows the timing from the generation start time of a supersonic gas flow to the irradiation time of a laser beam. The perspective view which shows notionally the laser welding apparatus which concerns on Embodiment 2 of this invention. Sectional drawing which cut | disconnects and shows the principal part of the laser welding apparatus of FIG. It is a figure which shows the structural example of the carrying in / out opening of a to-be-welded object, FIG.6 (a) is the front view which looked at FIG.6 (b) in the aa arrow direction, FIG.6 (b) is FIG. Is a cross-sectional view taken along line bb. The figure which shows the timing from the preparation stage of a to-be-welded object to carrying out.

  Hereinafter, embodiments of a laser welding apparatus and a welding method according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to a common component and the overlapping description is abbreviate | omitted suitably.

[Embodiment 1]
(Constitution)
FIG. 1 is a schematic view showing a state in which an aerodynamic window generator is installed on the upper part of a laser beam irradiation window of a welding chamber constituting a laser welding apparatus according to Embodiment 1 of the present invention. FIG. FIG. 1B is a cross-sectional view taken along the line aa and viewed in the direction of the arrow, and FIG. 1B is a side cross-sectional view taken along the line bb of FIG. 1A and viewed in the direction of the arrow. FIG. The laser welding device is a laser processing head (also called a welding torch) that is composed of a laser oscillator that generates a laser beam, an optical path that guides the laser beam, and a condensing optical system that focuses the transmitted laser beam to an appropriate size and adjusts the focal point. The laser processing head or the driving system for driving the workpiece, a welding chamber, a shield gas piping system, etc., are shown in FIGS. 1 (a) and 1 (b). The driving system is omitted. FIG. 2 is an explanatory diagram of the principle of the aerodynamic window generator.
Note that a carbon dioxide laser, a YAG laser, a fiber laser, or the like can be applied to the laser welding apparatus of the first embodiment.

  1A and 1B, the laser welding apparatus according to the first embodiment accommodates the workpiece 1 so that the workpiece 1 can be welded with the laser beam 3 under a reduced pressure environment. The laser beam irradiation window 23 is provided on the ceiling portion 22 of the casing 21 that constitutes the welding chamber 20, and the aerodynamic window generator 10 having the laser beam irradiation path 12 is placed outside the upper portion of the ceiling portion 22 of the casing 21. doing.

  Furthermore, a laser processing head (welding torch) 5 that irradiates the laser beam 3 toward the workpiece 1 is fixed to the upper part of the aerodynamic window generator 10 via an appropriate support member 6. The optical axis of the laser beam 3 irradiated from the laser processing head 5 is adjusted so as to pass through the substantially central part of the laser beam irradiation path 12 and the laser beam irradiation window 23.

Hereinafter, main parts constituting the laser welding apparatus of the first embodiment will be sequentially described.
First, the aerodynamic window generator 10 will be described.
The aerodynamic window generator 10 described in the present embodiment is an apparatus that generates a free vortex type aerodynamic window (also referred to as a supersonic free vortex type aerodynamic window, hereinafter abbreviated as an aerodynamic window) 11 by a supersonic gas flow 13. Point to.

  The aerodynamic window 11 is installed in place of the conventional optical glass window. As will be described later, the entrance of the laser light irradiation path 12 is aerodynamically formed by a supersonic gas flow 13 flowing in an arc shape from the nozzle toward the diffuser. It is partitioned from the atmosphere to maintain the differential pressure between atmospheric pressure and welding chamber internal pressure. The pressure distribution of the laser beam irradiation path 12 in the aerodynamic window generator 10 is such that the pressure distribution gradually decreases from the lower side of the aerodynamic window 11 toward the laser beam irradiation window 23 of the ceiling portion 22 of the housing 21. It has become.

The opening area of the laser irradiation path 12 and the laser beam irradiation window 23, as interference with the laser beam 3 is not generated at the time of welding, the ¹⁰ × 10mm ² ~40 × 40mm 2 a size of approximately square or rectangular or circular Is formed.

  Then, the aerodynamic window generator 10 according to the first embodiment separates the nozzle structure 14 and the diffuser structure 15 on both sides of the laser light irradiation path 12 by a dimension corresponding to the opening area of the laser light irradiation path 12. Furthermore, the side surfaces of the nozzle structure 14 and the diffuser structure 15 are hermetically closed with closing plates 16 and 17.

Hereinafter, each part which comprises the aerodynamic window production | generation apparatus 10 is demonstrated in detail.
The nozzle structure 14 has a thickness of about 10 to 40 mm corresponding to the opening area of the laser beam passage 12 (up and down method on the paper surface in FIG. 1A) and a width of about 2 to 3 times the thickness (see FIG. 1). 1 (a) is a rectangular block-shaped metal material having a left-right method on the paper surface) and a height (a front-back method on the paper surface in FIG. 1A).

  The nozzle structure 14 is formed by penetrating the air reservoir 14a at substantially the center position of the flat portion facing the blocking plates 16 and 17, and continuously from the air reservoir 14a toward the upper corner. The throat portion 14b and the nozzle 14c are formed so as to penetrate through. As shown in FIG. 2, the nozzle 14 c is formed in an asymmetric shape in which the width gradually increases from the inlet side communicating with the throat portion 14 b toward the outlet side. That is, of the inner wall of the nozzle 14c, the curved surface shape in the vicinity of the inner outlet end portion 14c1 and the outer outlet end portion 14c2 is formed in a substantially arc shape, and the radius of curvature near the inner outlet end portion 14c1 is the outer outlet end portion. It is formed smaller than the radius of curvature near 14c2.

  Further, the nozzle structure 14 is provided with a communication hole 14d for allowing the air reservoir 14a to communicate with the outside on the back side of the throat portion 14b. This communication hole 14d is configured to be connected to a high-pressure gas supply source (indicated as a gas cylinder in FIG. 1) 19 through a gas supply pipe 18 such as nitrogen gas or dry air.

  The exit end of the asymmetrical nozzle 14c described above extends from a predetermined center point O on the center line of the laser beam irradiation path 12 toward the upper corner of the nozzle structure 14 as shown in an enlarged view in FIG. It is located on the straight line H. That is, the inner outlet end portion 14c1 and the outer outlet end portion 14c2 of the nozzle 14c are formed on the straight line H.

  On the other hand, the diffuser structure 15 is formed of a rectangular block-shaped metal material having the same thickness as the nozzle structure 14, and the diffuser 15a is formed at a position facing the nozzle 14c.

That is, the diffuser 15a has an inner inlet end of the inner wall 15a1 at a position facing the inner outlet end 14c1 of the nozzle 14c, and an outer wall 15a2 at a position facing the outer outlet end 14c2 of the nozzle 14c. It is formed to have an outer inlet end. The outlet of the diffuser 15a is formed downward. In FIG. 2, Δθ is the central angle of the aerodynamic window 11 between the straight line H and the straight line connecting the center point O and the inner entrance end of the inner wall 15a1 of the diffuser 15a.
The inner wall 15a1 and the outer wall 15a2 of the diffuser 15a are machined so as to prevent separation of the gas flow.

Next, the principle of the aerodynamic window 11 generated by the nozzle 14c and the diffuser 15a will be described with reference to FIG.
A high-pressure gas such as nitrogen or dry air supplied from the high-pressure gas supply source 19 of FIG. 1 is temporarily stored in the reservoir tank 14a, then accelerated to supersonic speed in the throat section 14b, and supersonic gas from the nozzle 14c. It becomes a stream 13 and is ejected. The supersonic gas flow 13 forms a free vortex flow in which the flow velocity is inversely proportional to the radius R and flows into the diffuser 15a, thereby generating an aerodynamic window 11 at the entrance of the laser beam irradiation path 12. At this time, the radius from the center point O to the inner outlet end 14c1 of the nozzle 14c is R1, the Mach number based on the critical sonic velocity is M1, and similarly the radius from the central point O to the outer outlet end 14c2 is R2. If the Mach number based on the speed of sound is M2, the free vortex flow has a constant product of R and M, and the relationship R1 × M1 = R2 × M2 is established.

Returning to FIGS. 1A and 1B, the casing 21 constituting the welding chamber 20 will be described.
The casing 21 has a square cylindrical shape as a whole, one end is closed by the ceiling 22 except for the laser light irradiation window 23 located at the center, and the other end is an open end. The portion 24 is formed. The above-described aerodynamic window generator 10 is mounted and fixed on the outer upper portion of the ceiling portion 22 of the casing 21. And this housing | casing 21 is manufactured with metal materials, such as an aluminum alloy and a copper alloy, and even if the inside of the welding chamber 20 becomes high temperature and a negative pressure during welding construction, it can endure mechanically and thermally. It is.

  On the other hand, a seal member 25 is attached to the open end 24 of the casing 21 over the entire periphery. When the casing 21 is placed on the workpiece 1, the casing 21 and the casing 21 are mounted. The seal member 25 is crushed by the weight of the components mounted on it and is brought into close contact with the workpiece 1 so that the airtightness can be maintained.

  In addition, as performance required for the seal portion 25, when welding the workpiece 1 and the casing 21 while moving relatively, the contact portion is slidable, and the workpiece 1 is heated by welding heat input. Heat resistance, atmospheric pressure and pressure holding performance of the decompression section. The material and structure of the seal portion 25 may be optimal depending on the welding conditions and the size and shape of the welding chamber 20. When the heat input is relatively low, heat-resistant rubber or synthetic resin material having a high sealing performance, When the heat is high, a metal material having a sealing property, a brush material made of a metal material, and the like are conceivable.

  Further, the inside of the housing 21 is communicated with a vacuum pump (not shown) through the suction pipe 30 in order to form the welding chamber 20 in a reduced pressure environment state. Furthermore, a shield gas supply pipe 40 for spraying a shield gas (for example, argon gas, helium gas, nitrogen gas, etc.) is provided around the welding portion 2 of the work piece 1. The number of suction pipes 30, the number of vacuum pumps, and the number and position of shield gas supply pipes 40 are appropriately selected depending on the construction conditions and the construction object.

(Function)
Next, the operation of the first embodiment will be described with reference to FIGS.
At time t1 before laser welding is performed, first, the aerodynamic window generator 10 is operated. That is, the supersonic gas flow 13 ejected from the asymmetric nozzle 14c is sent to the diffuser 15a. Thereby, the aerodynamic window 11 is produced | generated by the upper part of the laser beam irradiation path 12, and, thereby, the inside of the welding chamber 20 is isolated from the atmosphere side. In addition, when performing laser welding under a reduced pressure environment, in order to sufficiently obtain the effect of increasing the penetration depth due to the reduced pressure, it is desirable that the pressure in the vicinity of the welding portion 2 is 10 kPa or less. Therefore, it is desirable that the pressure holding performance of the aerodynamic window 11 has a differential pressure holding capability of atmospheric pressure and 10 kPa or more.

  After generation of the aerodynamic window 11, at time t 2, the shielding gas is blown from the shielding gas supply pipe 40 to the welding work section 2, and a vacuum pump (not shown) is operated almost at the same time to depressurize the inside of the welding chamber 20. start.

  At time t3, the inside of the welding chamber 20 is in a reduced pressure environment of 10 kPa or less by a vacuum pump, and preparation for laser welding construction is completed. The laser light 3 irradiated from the light collecting system (not shown) by the operation of the laser oscillator (not shown) after this time passes through the generated aerodynamic window 11 and enters the laser light irradiation path 12, and further, the laser light irradiation window 23 enters the welding chamber 20 and is irradiated to the welding portion 2 of the workpiece 1 to perform laser welding.

  During this laser welding, the welding plume 4 rapidly rises upward from the welding portion 2, but the elevated welding plume 4 rides on the flow of the supersonic gas flow 13 that generates the aerodynamic window 11 and is externally connected from the diffuser 15 a. Therefore, it is possible to avoid damage to a welding torch and an optical device (not shown) located further above the aerodynamic window generator 10. As a result, it becomes possible to perform laser welding for a long time continuously even under a reduced pressure environment.

  In the first embodiment shown in FIG. 1, the welding chamber 20 and the workpiece 1 are connected to each other by a driving device (not shown) while maintaining the differential pressure between the atmospheric pressure and the welding chamber 20 with the seal portion 25 provided in the opening of the housing 21. Can move relatively, so that welding can proceed.

(effect)
When laser welding is performed using the laser welding apparatus configured as described above, the welding plume 4 that rises violently in a reduced pressure environment is discharged by the supersonic gas flow 13 flowing from the nozzle 14c to the diffuser 15a. Therefore, it is possible to prevent damage to equipment such as a welding torch and optical equipment above the welding construction portion 2. Further, since the aerodynamic window 11 is generated by making the supersonic gas flow 13 into a free vortex type arc-shaped flow capable of holding a differential pressure, the differential pressure between the atmospheric pressure and the negative pressure in the welding chamber 20 is set. The laser welding can be held for a long time stably in a reduced pressure environment.

(Modification)
When the work piece 1 is relatively small, the entire work piece 1 may be accommodated in a fixed welding chamber 20 and laser welding may be performed while moving the work piece 1. . In this case, since the seal portion 25 does not need to consider the sliding contact function, it is desirable that the bottom surface of the welding chamber 20 has an integral structure with the housing 21.

(Embodiment 2)
4 is a perspective view conceptually showing a laser welding apparatus according to Embodiment 2 of the present invention, FIG. 5 is a cross-sectional view showing a main part of the laser welding apparatus in FIG. 4, and FIG. FIG. 6A is a front view of FIG. 6B viewed in the direction of arrow aa, and FIG. 6B is a view of FIG. FIG. 7 is a cross-sectional view taken along line -b, and FIG. 7 is a diagram showing timing from the preparation stage of the workpiece to the time of unloading.

(Constitution)
Hereinafter, with reference to FIG. 4 thru | or FIG. 6, the structure of the principal part of Embodiment 2 of this invention is demonstrated.
4 and 5, the second embodiment is similar to the case 21 in place of forming the welding chamber 20 by partially covering the surface of the workpiece 1 with the housing 21 as in the first embodiment. The casing 21A formed in a shape is fixed on the welding work floor 50 to form the welding chamber 20, and the processing table 60 on which the workpiece 1 is placed is movably accommodated in the welding chamber 20. It is a thing.

As described above, the casing 21A of the second embodiment is arbitrarily opposed to the four side wall portions constituting the casing 21A because the workpiece 1 is accommodated together with the processing table 60 in the welding chamber 20. to two surfaces, the carrying port 70 ₁ and 70 ₂ is provided with a closure device ₈₀ 1, 80 ₂ of the door or the like for closing the loading opening ₇₀ 1, 70 ₂ in an airtight manner, respectively. If there is no necessity for explaining identify the loading opening ₇₀ 1, 70 ₂ and the closing device ₈₀ 1, 80 _2, simply carrying port 70, it referred to as the closure device 80.

On the other hand, the welding work floor 50 is provided with a rail 90 of a transfer device such as a conveyor in a loading / unloading path connected to the loading / unloading outlet 70 described above.
The processing table 60 described above can be moved in the x-axis and y-axis directions in the welding chamber 20 by a command from a drive system (not shown).

  In the welding work floor 50, the mounting surface of the workpiece 1 that is the reference surface does not change while the processing table 60 on which the workpiece 1 is mounted is moving on the xy plane. Furthermore, the surface is formed flat with a metal having high hardness, such as a surface plate.

  Further, an annular seal groove 51 is provided on the surface of the welding work floor 50 at a portion that contacts the open end 24 of the housing 21 </ b> A, and a sealing material 52 such as rubber is fitted into the annular seal groove 51. I am trying. Therefore, when the open end 24 of the housing 21A is positioned and placed in the seal groove 51 provided on the work floor 50, the seal material 52 is pushed by the weight of the housing 21A and other components as shown in FIG. The welding chamber 20 is crushed and in close contact with the open end 24, and the welding chamber 20 is highly sealed.

Next, an example of the carry-in / out port 70 and the closing device 80 will be described with reference to FIGS.
In the case of FIGS. 6A and 6B, the sliding door type closing device 80 configured to be slightly larger than the carry-in / out port 70 provided on the side wall portion of the housing 21A is moved up and down. The loading / unloading exit 70 is opened and closed.

  In the case of FIG. 6, when the inside of the welding chamber 20 is set to a negative pressure when the closing device 80 is in the solid line position shown in the figure, the closing device 80 is pressed against the side wall portion of the housing 21A via the packing 80P. The inside is sealed.

In the example of FIG. 6, the rail 90 is divided into the inner rail 90 _i and the outer rail 90 _o with the carry-in / out port 70 as a boundary. to inner rail 90 _i from the outer rail 90 _o by lifting by using the robot or the like together with the processing table 60 and the weld object 1, or it is necessary to transfer from the inner rail 90 _i to the outer rail 90 _o.

(Function)
Next, the operation of this embodiment will be described with reference to the time chart of FIG.
(A) First, the workpiece 1 is placed on the processing table 60 using an industrial robot outside the welding chamber 20 at time t1. Thereafter, the processing table 60 is transferred to the rail 90 on to the carrying port 70 ₁ of one of the housing 21A in this state.

(B) At time t2, it provided in the housing 21A, to open the closing device 80 ₁ of one of the carrying port 70 _1. Incidentally, the closure device 80 ₂ in the other carrying port 70 ₂ leave closed.

(C) The carry-in work is started at time t3. That is, lifting the work table 60 mounted with the object to be welded 1 using industrial robot is carried into the welding chamber 20 from the carry-out port 70 _1. This carrying-in work is completed at time t4. After the carry-in operation is completed, the processing table 60 is moved to a predetermined welding position or the vicinity thereof. The closing device 80 of the carry-in entrance 70 is closed at time t5 with a slight delay from time t4.

(D) Next, the aerodynamic window generator 10 is operated at time t6, and the aerodynamic window 11 is generated by the supersonic gas flow. That is, the supersonic gas flow 13 is ejected from the asymmetric nozzle 14 c and sent to the diffuser 15 a to generate the aerodynamic window 11 in the upper part of the laser beam irradiation path 12. The aerodynamic window 11 isolates the inside of the welding chamber 20 from the atmosphere side. In addition, when performing laser welding under a reduced pressure environment, in order to sufficiently obtain the effect of increasing the penetration depth due to the reduced pressure, it is desirable that the pressure in the vicinity of the welding portion 2 is 10 kPa or less. Therefore, it is desirable that the pressure holding performance of the aerodynamic window 11 has a differential pressure holding capability of atmospheric pressure and 10 kPa or more.

(E) At time t7 after the aerodynamic window 11 is generated, suction inside the welding chamber 20 is started to be reduced by suction with a vacuum pump. When the inside of the welding chamber 20 is depressurized, the closing device 80 that has already been closed is pressed against the peripheral portion of the carry-in / out port 70 on the side wall portion of the housing 21A via the packing 80P. Thereby, the inside of the welding chamber 20 is in a sealed state with a negative pressure.

(F) A shielding gas is sprayed on the welding work part at time t7 substantially at the same time as the suction by the vacuum pump.
(G) At time t8, when the inside of the welding chamber 20 becomes a preset reduced pressure environment of 10 kPa or less, preparation for laser welding is ready, so irradiation of the laser beam 3 from the laser processing head 5 is started.

  The laser beam 3 irradiated from the laser processing head 5 passes through the aerodynamic window 11 and enters the laser beam irradiation path 12, and further enters the welding chamber 20 through the laser beam irradiation window 23 and welds the work 1 to be welded. Part 2 is irradiated. The processing table 60 on which the workpiece 1 is placed moves in the welding chamber 20 on the XY plane as programmed in advance, and laser welding of the welding work part 2 is performed.

  The welding plume 4 generated at the time of laser welding is discharged to the outside through the diffuser 15 a by the supersonic gas flow 13 that generates the aerodynamic window 11, so that the laser processing head 5 positioned further above the aerodynamic window generating device 10. Damage can be avoided, and laser welding can be performed continuously for a long time even in a reduced pressure environment.

When the laser welding operation is completed at time t9, the irradiation of the laser beam 3 is stopped.
Thereafter, the suction by the vacuum pump and the supply of the shielding gas are stopped at time t10, and the supersonic gas flow is stopped at time t11.

  In addition, if it is after the time t9 when the irradiation of the laser beam 3 is stopped, the timing of the end of suction by the vacuum pump, the timing of the end of supply of the shield gas, and the timing of the end of supersonic gas flow are not necessarily shown in FIG. It is not necessary to follow the steps (f) to (f).

(H) Then, opening the closing device 80 ₁ in time t12, the use of industrial robots described above and at time t13 unloading the object to be welded 1 and the machining table 60 from the carry-out port 70 _1.

In the above description, the side wall portion facing the housing 21, a total of two positions carrying entrance ₇₀ 1, 70 ₂ and the closing device ₈₀ 1, 80 ₂ Although provided, carrying port may be in one place Further, the carry-in / out port may be divided into a carry-in port and a carry-out port.

(effect)
As described above, according to the second embodiment, in addition to the operational effects of the first embodiment, a carry-in / out port for an object to be welded is provided on the side wall portion of the casing constituting the welding chamber. Since the opening / closing operation is performed by the closing device, it is possible to improve the efficiency of the welding operation.

As mentioned above, although several embodiment of this invention was described, these embodiment was shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... To-be-welded object, 2 ... Welding construction part, 3 ... Laser beam, 4 ... Welding plume, 5 ... Laser processing head, 6 ... Support member, 10 ... Aerodynamic window production | generation apparatus, 11 ... Aerodynamic window, 12 ... Laser beam irradiation 13: Supersonic gas flow, 14 ... Nozzle structure, 14a ... Reservoir tank, 14b ... Throat section, 14c ... Asymmetric nozzle, 14d ... Communication hole, 15 ... Diffuser structure, 15a ... Diffuser, 16, 17 DESCRIPTION OF SYMBOLS ... Blocking plate, 18 ... Gas supply pipe, 19 ... Gas supply source, 20 ... Welding chamber, 21, 21A ... Housing, 22 ... Ceiling part, 23 ... Laser light irradiation window, 24 ... Open end part, 25 ... Seal part 30 ... Vacuum pump suction pipe, 40 ... Shield gas supply pipe, 50 ... Welding work floor, 51 ... Seal groove, 52 ... Sealing material, 60 ... Processing table, 70 (70 ₁ , 70 ₂ ) ... Loading / unloading outlet, 80 (80 ₁ 80 ₂₎ ... closure device (door), rails 90 ... transfer device.

Claims (8)

Formed in a cylindrical shape, with one end closed except for the laser light irradiation window, and by attaching a seal member to the open end that is the other end and contacting the work piece or welding work floor A housing forming a welding chamber;
An aerodynamic window that is fixed at the upper position of the laser light irradiation window, generates a free vortex aerodynamic window by a supersonic gas flow, and aerodynamically partitions the inside of the welding chamber and the atmosphere by the free vortex aerodynamic window. A generating device;
A laser processing head installed at an upper position of the aerodynamic window generator;
A decompression device for bringing the inside of the welding chamber into a decompressed environment state from atmospheric pressure;
An apparatus for relatively moving the casing and the work piece;
Laser welding equipment equipped with.   The aerodynamic window generator is configured to include a thick plate-like nozzle structure having a reservoir, a throat portion, and a nozzle, and a thick plate-shaped diffuser structure having a diffuser. The laser welding apparatus according to 1.   3. The laser welding apparatus according to claim 1, wherein the casing is air-tightly and slidably mounted on the workpiece through the seal member.   The housing accommodates the workpiece to be welded and a processing table on which the workpiece to be welded is placed in the welding chamber, and a carry-in / out port for the work to be welded and the processing table on a side wall portion, and the carry-in / out port. 3. The laser welding apparatus according to claim 1, further comprising: a closing device that opens and closes, and further, the open end portion is in contact with and fixed to the welding work floor via the sealing material.   The laser welding apparatus according to claim 3 or 4, wherein the sealing material is made of any one of rubber materials, resin materials, metal sealing materials, or a combination thereof.   A laser welding method, wherein welding is performed using the laser welding apparatus according to any one of claims 1 to 5.   The laser welding method according to claim 6, wherein welding is performed while supplying a shielding gas for laser welding into the welding chamber.   8. The laser welding method according to claim 6, wherein laser welding is performed while maintaining a state in which the pressure in the welding chamber is reduced to 10 kPa or less.

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