JPH06102276B2 - Laser welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is a welding method by laser irradiation.

[Conventional technology]

The laser light oscillated from the laser oscillator is focused by the condenser lens, and is welded or cut while irradiating the workpiece, the groove,
Laser processing for performing recesses, surface shaving, etc. is known and is currently used in various fields. Among them, especially in laser welding, the absorption rate of the laser gradually increases as the temperature of the metal surface rises due to the laser irradiation, and at the same time when the melting starts, the evaporation phenomenon also occurs, and the laser beam is deepened by the reflection of the wall surface of the hole. At the same time, the wall begins to melt. It is known that such laser welding can perform so-called keyhole welding in which welding is performed while directly applying energy to the bottom of the hole without depending on the conduction heat of the surface point heat wave.

[Problems to be solved by the invention]

Laser welding has the advantages that a smooth bulging beat is formed by keyhole welding, that there is little heat effect and that sufficient welding strength is obtained, but this effective welding is started. Before, when the laser beam was moved to irradiate a new welded part, most of the irradiated laser was reflected on the metal surface, and several percent of the irradiated energy
However, it has a drawback that the welding speed becomes slow because it is only effectively used.

Also, when assembling metal parts without welding, the joint surfaces of each part are finished by cutting, etc.
It is common practice to finish the cut surface with a file or scraper, or join the polished surfaces together with bolts. When connecting parts with bolts in this way, a flange portion protruding for that purpose is provided, the bolt is passed through here, and tightened with a nut, or one part is provided with a bolt through hole and the other A screw hole is provided in the component, and a bolt penetrating the bolt hole is screwed into the screw hole for fastening. As described above, according to the conventional method of joining parts by bolts, it is necessary to provide a flange portion through which the bolts pass, and to machine bolt holes and screw holes. Since the shape of the parts is such that the bolts are inserted, it is not possible to provide a structure for blocking the bolts above the holes on the side where the bolts are inserted. Therefore, it is desired to join the parts by welding.

In view of such problems, an object of the present invention is to provide a laser welding method capable of increasing the welding speed as compared with the conventional method.

[Means for solving problems]

In order to achieve this object, the laser welding method of the present invention,
Laser welding in which both joining surfaces of both members to be joined are opposed to each other and held at a predetermined position, and the both members and the irradiation laser are relatively moved to irradiate a laser along the opposed joining portions to perform welding. The method is characterized in that a large number of craters are formed in advance by electric discharge machining on both the joint surfaces.

Further, powder particles of a metal or alloy or powder particles of a magnetized magnetic material are interposed between the both joint surfaces. Further, the relative movement between the two members and the irradiation laser is numerically controlled.

Further, in order to accurately perform the relative movement between the both members and the irradiation laser, numerically controlled movement is performed in the X-axis and Y-axis directions perpendicular to each other in a state in which each of the assembled parts is accurately held. It was mounted so that it could rotate on the R-axis, which is perpendicular to the plane of the Y-axis. On the other hand, the housing holding the laser focusing lens is mounted so as to be rotatable about an R'axis parallel to the X axis and slidable at a right angle to the R'axis at the tip of an arm that moves up and down in the Z axis direction. The radius of gyration of the housing can be changed by numerically controlling the movement of the housing itself in the axial direction.

[Action]

Since many minute craters (irregularities) are formed by electrical discharge machining on both joint surfaces to be welded, the reflectance of the irradiation laser on the joint surfaces is reduced and the laser energy is more efficient than before. It is absorbed by and improves the welding speed.

Also, by forming craters by electric discharge machining on both joint surfaces to be welded and by interposing powder particles of metal or alloy on both joint surfaces by injection or coating, laser energy absorption efficiency is further improved and welding is performed. Speed is improved.

Further, when the powder particles to be interposed between both the bonding surfaces are magnetized magnetic materials, the metal and alloy powder particles can be easily fixed to the bonding site by the magnetic attraction force when the bonding member is a magnetic material.

Further, both members to be welded are fixedly held on a table by positioning both joining surfaces to be joined so as to be in contact with each other, and the table is fixed to the X and Y axes orthogonal to each other by programmed numerical control. Directional movement control or further X, Y
A housing that controls rotation about an R axis that is orthogonal to the axis and that further holds a focusing lens of the laser, that is, Z-Y that includes a Z axis that is perpendicular to the X and Y axis directions of the optical axis of the irradiation laser.
In the plane, the rotation of the axis R'rotating about an axis parallel to the X axis perpendicular to the axis is controlled, and the turning radius of the housing is changed and adjusted. By irradiating the two surfaces, it is possible to weld both joint surfaces accurately and accurately, and it is possible to uniformly assemble a large number of parts having the same shape at a high speed.

Also, the depth of the weld is adjusted within the range of the depth of the keyhole which can be reached by the energy of the laser. Also, during welding, an inert gas such as argon is blown to prevent oxidation and at the same time prevent the laser from being absorbed by the metal vapor.

〔Example〕

The present invention will be described with reference to the drawings. In FIG. 1, an X-axis slide table 2 having a guide surface in the X-axis direction is fixed on a bed 1, and the X-axis slide table 2 is attached thereto by a servo motor 3.
Attach the saddle 4 that moves in the axial direction. The saddle 4 has a guide surface in the Y-axis direction that is perpendicular to the X-axis, and a table 6 that is moved by the servomotor 5 in the Y-axis direction is mounted on the guide surface. A table 8 for indexing by rotating with an R-axis perpendicular to the X-axis and the Y-axis by a servo motor 7 is detachably attached to the table 6, and both joining surfaces to be welded are opposed to each other. Position it in place and fix it. A column 11 fixed to the bed 1 has a head 14 which is moved in a Z-axis direction which is perpendicular to the X-axis and the Y-axis by a screw 13 which is rotated by a servomotor 12. An arm 16 is provided which rotates about an R'axis parallel to the axis. A laser oscillator 17 is provided at a base end portion of the arm 16, and a housing 19 is provided at a tip end portion of the arm 16 so as to be slidable by a servomotor 18 in a direction parallel to a rotation surface of an R'axis parallel to the Z-Y plane. The housing 19 pivots as the arm 16 pivots, and the turning radius of the pivot can be changed and adjusted by sliding in a direction parallel to the pivot plane of the R'axis. Reference numeral 21 is an NC device (numerical control device) for controlling the servomotors 3, 5, 7, 12, 15, 18 and the laser oscillator 17 described so far.

The part described with reference to FIG. 1 will be described in more detail with reference to FIG. The screw 13 is screwed with a nut 22 fixed to the head 14 to move the head 14 up and down. A worm wheel 24 that meshes with a worm (not shown) provided on a shaft 23 rotated by a servomotor 15 is fixed to a shaft 25 with a nut 26, and the shaft 25 is supported by a bearing 28 enclosed in a head 14 by a plate 27. It is rotatably supported. Then, the arm 16 is fixed to a disc 29 provided integrally with the shaft 25. As the laser oscillator 17, those disclosed in JP-A Nos. 60-107,877, 107,878, 107,880, 170,991, and 115,280 can be used, and the laser emitted from the laser oscillator 17 can be used.
20 changes the optical path by reflecting mirrors 30 and 31, and condensing lens 32
Are focused by and are focused on the welded parts of the parts 9 and 10. Housing 19 in which condenser lens 32 is fixed by lens fixing member 33
Is slidably held by an arm 16, and the sliding is fixed to a housing 19 and a helical gear 35 that meshes with a helical rack 34 that also functions as a slide key is rotated by a servomotor 18 via a shaft 36. By doing. The sliding of the housing 19 focuses the laser on the changing welding positions of the parts 9, 10. Further, depending on the shape of the joint portion of the components 9 and 10, the housing 19 is rotated with the rotation of the arm 16, and the turning radius of the rotation is changed by sliding the housing 19 to adjust the laser. Irradiate along both joint surfaces of 10 and 10. The welding position of these parts 9 and 10 is detected by a detector 38 attached to the nozzle 37, and the detection signal is NC through an amplifier or the like (not shown).
The signal is input to the device 21 and is one of the signals for controlling each part. Although only one detector 38 is shown in the figure, the number is not limited to one, and a plurality of detectors 38 may be provided so that the laser irradiation height, position and direction can be accurately set. For example, parts 9,10
As for the distance between the condenser lens 32 and the condenser lens 32, infrared rays can be used to detect the position where the infrared rays emitted by the molten metal are most intense, or a detector using ultrasonic waves can be used. The magnetized magnetic powder is inserted between the bonding surfaces, coated or intervened by tape-like attachment, and the magnetic field of this magnetic powder is detected to detect the bonding site, and this detection signal is input to the NC unit 21. However, it is also possible to control the relative movement between the components 9 and 10 and the irradiation laser so that the irradiation laser always follows the bonding portion so that the irradiation laser is always irradiated from the direction perpendicular to the bonding portion. The use of the magnetic powder is effective not only for detecting the welded portion, but also when the parts 9 and 10 are magnetic materials, the powder particles are fixed between both joint surfaces by the magnetic attraction force. Even if the powder particles of the metal or alloy to be interposed between the two joint surfaces are not magnetized, the existence of the powder particles serves to increase the absorption efficiency of laser energy and improve the welding speed. Further, usually, the relative movement between the components 9 and 10 and the irradiation laser is performed by pre-programmed numerical control, and in this case, the components 9 and 10 are arranged so that both joint surfaces are located at the programmed relative movement position. Position on the table and hold it in place. As powder particles of metals and alloys, W that can be obtained by reduction of oxides,
Mo, Fe, Ni, Co powder, Cu, Ni powder that can be produced by reduction from aqueous solution, Fe, Ni powder that can be obtained by thermal decomposition of metal carbonyl, Cu that can be obtained by electrolysis of molten salt , Ag, Fe powder, ultra-hard material powder obtained by crushing, and other alloy powder obtained by pulverizing by spraying water, air, inert gas, etc. to the molten metal flow flowing out from the nozzle can be used . Further, these metal or alloy powder particles can be used as a mixture with an organic substance such as CMC or an activator such as borax or boric acid. In addition, the nozzle 37 through the pipe 39
An inert gas such as argon is blown into the inside of the laser to blow it from around the laser 20 to prevent oxidation of the welded portion and at the same time prevent the laser from being absorbed by the metal vapor.

〔The invention's effect〕

As described above, according to the present invention, by forming a large number of craters by electrical discharge machining in advance on both joint surfaces held facing each other at a predetermined position, the reflection of the irradiation laser on the joint surfaces is reduced. Thus, the absorption efficiency of laser energy can be increased and the welding speed can be improved. Further, by interposing powder particles of a metal or an alloy between both joint surfaces, it is possible to further improve the absorption efficiency of laser energy and improve the welding speed.

In addition, the relative position of the part to be joined and the laser can be determined by the X, Y axis, X, Y, Z
Welding can be automated by NC control of the axes or even the X, Y, Z, and R axes, and a large amount of parts with the same shape can be assembled by welding uniformly with high speed. Further, if a magnetized magnetic material is used as powder particles of metal or alloy, it is possible to perform welding by making the laser follow the joining site by detecting the magnetism of the powder particles.

[Brief description of drawings]

FIG. 1 is an external view of the present invention, and FIG. 2 is a sectional view of a main part of FIG. 1 …… Bet 6 …… Table 8 …… Rotating table 9,10 …… Parts 16 …… Arm 17 …… Laser oscillator 19 …… Housing 20 …… Laser

Claims (7)

[Claims] 1. A laser beam is radiated along the facing bonding portion by holding both bonding surfaces of the members to be bonded facing each other at a predetermined position and moving the both members and an irradiation laser relatively to each other. In the laser welding method of welding by welding, a large number of craters are formed in advance by electric discharge machining on the both joint surfaces. 2. The laser welding method according to claim 1, wherein the movement of both members is controlled in the X and Y axis directions perpendicular to each other. 3. The laser according to claim 1, wherein the both members are controlled to move in the X and Y axis directions perpendicular to each other, and rotationally controlled about an R axis orthogonal to the X and Y axes. Welding method. 4. The relative movement between the both members and the irradiation laser is
The optical axis of the irradiation laser is around an axis parallel to the X axis and Z
The laser welding method according to claim 1, wherein the laser welding is performed by controlling rotation of a housing having a focusing lens that irradiates the laser so as to rotate in a Y plane. 5. The laser welding method according to claim 1, wherein both the joint surfaces have powder particles of metal or alloy. 6. The laser welding method according to claim 1, wherein the both joint surfaces have powder particles made of a magnetized magnetic material. 7. The laser welding method according to claim 1, wherein the relative movement between the both members and the irradiation laser is performed by numerical control.