JP2002103075A - Laser/plasma combined machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small-output YAG laser having machining performance comparable to a high output YAG laser as well as high machining efficiency and stable plasma generation. SOLUTION: The device is equipped with a nozzle member 1 having a nozzle 2 through which the optical axis 22 of a YAG laser optical flux 21 penetrates; insulation members 6, 8 which support the nozzle member 1 and which surround a part of the transmitting space of the laser optical flux 21; a solid bar-like plasma electrode 18 having a pointed tip end; electrode supporting members 12, 14 which hold the plasma electrode 18 at a posture and position pointed to the nozzle 2 from a position inclined to and receded from the optical axis 22 and which are connected to the insulation members 6, 8; and a member 16 which joins the electrode supporting members 12, 14 to a laser head 17 for radiating a laser optical flux 21. The nozzle member 1 is provided with a conical surface 3 as the inner surface, while the insulation member 8 is provided with a spiral gas-injecting flow passage 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus for performing processing such as welding, cutting, drilling, heating, and melting, and more particularly to a processing apparatus combining laser and plasma.

[0002]

2. Description of the Related Art For example, laser welding is capable of low distortion and high speed welding, but the laser beam has a small spot diameter, so the gap tolerance is small in butt welding, and a high butt precision of the welding material is required. You. JP-A-2-52183
Discloses a laser welding method that uses a plasma arc together with a plasma welding of a butt joint prior to CO ₂ laser irradiation in order to realize butt welding with a CO ₂ laser even if the butt accuracy is low. Have been.

According to this method, the gap tolerance is increased and the quality of laser butt welding is improved. However, the efficiency of laser welding does not improve much. Here, the efficiency is the thickness of the material to be welded × the welding speed with respect to the laser power.

Japanese Patent Application Laid-Open No. Hei 10-180479 discloses a method in which a ring-shaped or conical cylindrical plasma electrode for generating plasma and a nozzle member are provided at the tip of a laser torch, and a laser beam is applied to a central opening of the plasma electrode. There is disclosed a welding torch for simultaneously irradiating a plasma jet and a laser beam to the same point of a material to be welded. It is explained that the laser beam converging through the center of the plasma jet acts to narrow the plasma jet, thereby increasing the plasma jet density (energy density) acting on the material to be welded and improving the welding efficiency. Have been.

[0005] However, a ring-shaped or cylindrical plasma electrode can generate an arc at all points in one round, but the arc remains at one point and is consumed there, disturbing the electrode shape and causing unstable discharge characteristics. It is thought that it is easy to become. That is, it is assumed that the stable operation time of the plasma electrode is short.

[0006] In Japanese Patent Application Laid-Open No. Hei 10-216979, a conical space connected to a nozzle at the lower end is formed at the tip of a laser torch, and a ring-shaped or conical cylindrical cathode electrode and an anode electrode are provided vertically. In addition, a laser processing head using a non-transfer type plasma, in which a plasma arc current flows between them, is disclosed. However, also in this case, it is considered that the arc remains at one point, is consumed there, and the shape of the electrode is disturbed, and the discharge characteristics are likely to be unstable. That is,
It is assumed that the stable operation time of the plasma electrode is short. In addition, since non-transfer type plasma generation is performed, it is considered that the distance tolerance between the head and the material to be welded is very small.

[0007] Japanese Patent Application Laid-Open No. 5-69165 discloses that a cylindrical electrode for TIG welding is provided at the tip of a laser torch.
There is disclosed a TIG welding torch combined with laser for irradiating a material to be welded by passing a laser beam through a central opening of the electrode. Also in this case, it is considered that the arc remains at one point, is consumed there, and the shape of the electrode is disturbed, and the discharge characteristics are likely to be unstable.

Japanese Patent Application Laid-Open No. 9-122950 discloses a composite welding head in which a TIG welding electrode is arranged at an optical axis position of a lens group for condensing laser light. This TIG welding electrode is a solid rod-shaped electrode of a round pencil, and it is assumed that the TIG arc concentrates at the tip of the lower end, and the arc is stable. However, since the lower end of the TIG is exposed outside the torch and the laser beam converges just below the tip of the electrode, the laser is blocked by the welding fume, and the improvement in welding efficiency is presumed to be low.

[0009]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a laser / plasma combined processing apparatus having high processing efficiency and stable plasma generation. A second object is to obtain processing performance equivalent to that of a high-output YAG laser with a small-output YAG laser.

[0010]

(1) A nozzle member (1) having a nozzle (2) through which an optical axis (22) of a laser beam (21) passes;
An insulating member (6, 8) supporting the nozzle member (1) and surrounding a part of a transmission space of the laser beam (21) toward the nozzle (2); a solid rod-shaped plasma electrode (18); The insulating member, which holds the plasma electrode (18) in a posture and a position where the plasma electrode (18) is inclined with respect to the optical axis (22) and is directed toward the nozzle (2) from a position retracted from the optical axis (22). An electrode support member (12, 14) coupled to (6, 8); and a means (16) for coupling the electrode support member (12, 14) to a laser head (17) for emitting the laser beam (21). ); A combined laser / plasma processing apparatus.

To facilitate understanding, reference numerals in parentheses for corresponding elements or corresponding items in the embodiment shown in the drawings and described later are added for reference. The same applies to the following.

According to this, the laser beam converging through the nozzle (2) passes through the plasma jet generated below the plasma electrode and acts on the plasma jet, and the plasma jet density (energy density) acting on the material to be welded And welding efficiency is improved. Since the plasma electrode (18) is in the shape of a solid rod having a sharp tip, the plasma arc concentrates on the sharp tip and stays there to stabilize. Therefore, the stable operation time of plasma irradiation is long. Since the plasma jet repels fumes, there is little interruption of energy by them, and from this point also, welding efficiency is improved.

[0013]

(2) The inner surface of the nozzle member (1) where the nozzle (2) is open is a conical surface (3) centered on the nozzle (2) and having the bottom as the center; The insulation members (6, 8)
On the inner peripheral surface surrounding the transmission space of the luminous flux (21), a plasma gas flow path (9) opened in a direction along the circumference is provided.

According to this, the plasma gas blown from the plasma gas flow path (9) converges into a small-diameter swirl along the conical surface (3) while swirling, is ionized by the arc of the electrode (18), and 2 comes out as a plasma jet. Since it turns in a cyclone shape around the optical axis, the directional stability of plasma jet injection is high.

(3) The opening of the electrode support member (12, 14) for passing the laser beam (21) is formed by the insulating member (6, 14).
The diameter is smaller than the inner peripheral surface of 8). Thereby, the electrode support members (12, 14) block the movement of the swirling flow of the plasma gas in the direction returning to the laser light source, and the force of the swirling convergence is strong.

(4) The nozzle member (1) and the plasma electrode
(18) a pilot power supply (HF, PSp) for generating a pilot plasma; and a main power supply (a main power supply for supplying a main plasma arc current between the workpiece (OB1) and the plasma electrode (18)). PSp); As a result, a plasma arc flows from the workpiece (OB1) to the plasma electrode (18). That is, a transition type plasma is generated. Processing object
Since the laser beam hits the plasma arc base point of (OB1),
High welding efficiency. Welding performance equivalent to that of a high-power laser can be obtained with a low-power laser.

(5) The laser is a YAG laser. YA
Since the G laser has a light absorption rate of the metal material several times that of the CO ₂ laser, efficient welding is possible. Further, since the wavelength is 1/10 of that of the CO ₂ laser, it is hardly affected by plasma generated at the time of welding. Since the YAG laser can be transmitted by a flexible optical fiber, handling is easy and an articulated robot can be used. Also, 100
Transmission up to about m away is possible. on the other hand,
Since the initial cost of the YAG laser is high, when introducing a plurality of equipment such as an automobile production line,
Although the equipment cost is enormous, the laser beam is divided into time (time sharing) and space (power sharing)
Thus, the data can be distributed to a plurality of processing stations and used for processing, and high utilization efficiency can be obtained.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0019]

FIG. 1 shows a main part of a first embodiment of the present invention. The outer flange of the nozzle member 1 having the nozzle 2 around the optical axis 22 of the YAG laser beam 21 of the YAG laser head 17 is
It is fixed to the nozzle receiver 6 by a plurality of screws (not shown) (four distributed at a 90-degree pitch around the optical axis 22). The small-diameter cylinder of the nozzle member 1 is inserted into the round hole of the nozzle receiver 6, and the outer peripheral surface of the cylinder compresses the O-ring 7. Further, the outer flange of the nozzle member 1 compresses the O-ring 5 by a plurality of screws (not shown). A ring-shaped cooling water flow path 4 is provided at the neck of the small-diameter cylinder of the nozzle member 1, and the flow path 4 is hermetically sealed by O-rings 5 and 7. The nozzle receiver 6 has an injection port for supplying cooling water to the flow path 4 and a discharge port for draining cooling water from the flow path 4, but these are not shown.

At the inner end surface of the small-diameter cylinder of the nozzle member 1, there is a conical surface 3 which is continuous with the nozzle 2 at the bottom and defines a conical space.

A ring-shaped groove is cut in the inner end face of the nozzle receiver 6, and a substantially small-diameter ring-shaped plasma gas port 8 is fitted therein, and a substantially large-diameter ring-shaped gasket is provided radially outward. 10, a ring-shaped plasma gas flow space 23 is defined between the gas flow passage 8 and the outer peripheral surface of the gas port 8. The gas port 8 is provided with a plurality of plasma gas injection nozzles 9 that open on the outer peripheral surface and the inner peripheral surface and penetrate the gas port 8 in a tangential direction of the inner peripheral surface. The gasket 10 has a plasma gas injection port 11 communicating with the plasma gas flow space 23.

Above the plasma gas port 8 and the gasket 10, there is an electrode holder 12 whose center hole 13 has a diameter smaller than the diameter of the inner peripheral surface of the gas port 8. It serves as an eave of the space, and suppresses upward diffusion of the plasma gas swirling from the plasma gas injection nozzle 9 into the space inside the gas port 8 to increase the swirling force.

As shown in the figure, a solid rod-like (round pencil) plasma electrode 1 having a sharp tip is provided on an electrode holder 12.
8 has a through-hole for receiving the nozzle 8 from the position where it is inclined with respect to the optical axis (torch axis) 22 and directed away from the optical axis 22 toward the nozzle 2.
Is penetrating. The electrode holder 12 has a screw hole from the outer peripheral surface to a through hole, and the plasma electrode 18 is fixed to the electrode holder 12 by tightening a fastening screw 19 screwed into the screw hole. 20 is a lock nut.

An insulating table 14 is mounted on the electrode holder 12. Insulation table 14, electrode holder 12, bracket 10
And the nozzle receiver 6 is provided with a plurality of bolts 15 (1 around the optical axis 22) which are screwed into the nozzle receiver 6 through them.
(Three pieces distributed at a pitch of 20 degrees).

A female screw cylinder 16 with a flange is screwed to a male screw on the outer periphery of the lower end of the YAG laser head 17.
The insulating table 14 is fixed to the female screw cylinder 16 with a plurality of screws (three distributed at a pitch of 120 degrees around the optical axis 22) through the threaded holes of the flange and screwed into the insulating table 14. I have.

In this embodiment, the electrode holder 12 is made of a conductor (made of copper) so that the electric field of the arc discharge is concentrated on the sharp tip of the plasma electrode 18 so as to avoid concentration of the electrolysis other than the tip of the electrode. Accordingly, in order to insulate the electrode holder 12, the nozzle receiver 6, the plasma gas port 8, the gasket 10, and the base 14 are made of an insulator (ceramic). The nozzle member 1 is a conductor (made of copper).

A pilot power supply circuit including a pilot power supply PSp, a high-frequency high-voltage trigger circuit HF and a pilot switch SWp is connected to the plasma electrode 18 and the nozzle member 1, and is connected to the plasma electrode 18 and the butt welding target material OB1. Is connected to a main plasma power supply circuit including a main plasma power supply PSm and a main switch SWm.

The supply of cooling water and plasma gas is started, the supply of gas for purging the lens for laser focusing is also started in the laser head 17 if necessary, the pilot switch SWp is turned on, and the trigger circuit H is turned on.
By driving F, an electric discharge is triggered between the nozzle member 1 and the plasma electrode 18. Thus, when the pilot plasma is ignited, the trigger circuit HF is turned off and the main switch SWm is turned on. As a result, a main plasma arc is generated between the welding target material OB1 and the plasma electrode 18, and a plasma welding operation state is set. Here, the YAG laser beam 2
When the injection of 1 is started, a laser / plasma combined, high-efficiency butt welding operation state is set.

Second Embodiment FIG. 2 shows a main part of a second embodiment of the present invention. In the second embodiment, the plasma gas port 8, the gas injection nozzle 9 and the gas injection port 11 for swirl injection of the plasma gas of the first embodiment are omitted, and instead, the plasma gas is injected into the YAG laser head 17. A port 24 is provided, from which plasma gas is supplied into the head 17. Other structures are the same as those of the first embodiment. In the second embodiment, the plasma gas entering the head 17 forms an axial flow toward the nozzle 2 and flows down the head 17 to be ejected from the nozzle 2 to the outside. In this process, plasma is generated by ionization by the arc between the nozzle 2 and the lower end of the electrode 18.

Third Embodiment FIG. 3 shows a main part of a third embodiment of the present invention. In the third embodiment, a cone 25 for defining a gas flow path is added to the second embodiment to cover the laser beam, and the inside of the head 17 and the cone 2 are formed.
The plasma gas is supplied to the inner space of the nozzle receiver 6 through the space outside the nozzle 5. Within the insulating table 14 is a baffle 26, which is a half-circular plate ring half, which is used to concentrate the plasma gas flow around the electrode 18, outside the cone 25, in the center hole 13. The right half is closed. Other structures are the same as in the second embodiment.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a main part of a third embodiment of the present invention.

[Explanation of symbols]

 1: nozzle member 2: nozzle 3: conical surface 4: cooling water channel 5: O-ring 6: nozzle receiver 7: O-ring 8: plasma gas port 9: gas injection nozzle 10: gasket 11: gas injection port 13: center hole 14: Insulating table 15: Bolt 16: Female screw cylinder 17: YAG laser head 18: Plasma electrode 19: Fastening screw 20: Lock nut 21: YAG laser beam 22: Optical axis 23: Gas flow space 24: Gas injection port 25: Cone 26: Baffle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Clothing Bag 7-6-1 Higashi-Narashino, Narashino-shi, Chiba F-term (Reference) 4E068 AA01 BC00 CD15 CH02

Claims (5)

[Claims] A nozzle member having a nozzle through which an optical axis of the laser beam passes; an insulating member supporting the nozzle member and surrounding a part of a transmission space of the laser beam toward the nozzle; An electrode support member coupled to the insulating member, the plasma electrode holding the plasma electrode in a posture and a position facing the nozzle from a position where the plasma electrode is inclined with respect to the optical axis and retracted from the optical axis; And a means for coupling the electrode support member to a laser head that emits the laser beam. 2. The inner surface of the nozzle member where the nozzle is open is a conical surface centered on the nozzle and bottomed on the nozzle;
The insulating member has a plasma gas flow path opened in a circumferential direction on an inner peripheral surface surrounding a transmission space of the laser beam;
The laser / plasma combined processing apparatus according to claim 1. 3. The laser / plasma combined processing apparatus according to claim 2, wherein an opening of said electrode support member for passing said laser beam is smaller in diameter than said inner peripheral surface of said insulating member. 4. A power supply for generating a pilot plasma between the nozzle member and the plasma electrode; and a main power supply for supplying a main plasma arc current between the workpiece and the plasma electrode. 4. The combined laser / plasma processing apparatus according to claim 1, 2 or 3. 5. The method according to claim 1, wherein the laser is a YAG laser.
5. The laser / plasma combined processing apparatus according to claim 2, 3 or 4.