JPH03128183A - Laser beam machine - Google Patents

Abstract

PURPOSE:To eliminate the limitation on the installation of the central position of condenser lenses and a return mirror by a through-hole in the central part and 1st and 2nd optical fibers provided coaxially with this hole with the laser beam machine for the inner peripheral surface of a cylindrical work. CONSTITUTION:A support 21 having the 1st optical fiber 31 insertion hole in the central part of an outside cylindrical tube 15 and a cylindrical case 23 which is mounted at one end thereof, rotates coaxially with the insertion hole and has the laser through-hole in the peripheral side part on the front end side are provided. The rear end of the 2nd optical fiber 35 is mounted freely rotatably to one end of the support 21 so as to coaxially face the through-hole and the front end thereof is held non-coaxially with the through-hole. The condenser lenses 38 and return mirror 39 for the laser beam emitted from the 2nd optical fiber are provided in the case 23. The 2nd optical fiber can be rotated without twisting the fiber. The disposition of the condenser lenses with the deviation from the center of the case 23 is possible and the free setting of the focal length and converging angle is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a laser processing device for applying laser pressure to the inner peripheral surface of a cylindrical workpiece.

(Prior Art) When performing laser processing such as welding on the inner circumferential surface of a cylindrical tube body using a laser beam, a laser processing apparatus as shown in FIG. 2 has conventionally been used.

That is, numeral 1 in the figure is a shaft-shaped support. The tip of this support body 1 is formed into a narrow diameter portion 2, and in this narrow diameter portion 2, the rear end west peripheral surface of a cylindrical case 3 whose tip is closed is rotatably supported by a pair of bearings 4. has been done. An internal gear 5 is provided on the rear end surface of the case 3, and a spur gear 6 meshes with the internal gear 5. This spur gear 6 is fitted onto a rotating shaft 8 of a motor 7. The motor 7 is accommodated and held in four parts 9 formed on the support 1. Therefore, when the motor 7 operates and the spur gear 6 rotates, the case 3 is rotationally driven via the internal gear 5 meshed with the spur gear 6.

An optical fiber 11 is pushed through the center of rotation of the support 1. Laser light enters the optical fiber 11 from the rear end face and exits from the front end face. Laser light emitted from the tip end face of the optical fiber 11 enters a pair of condensing lenses 12 . These condensing lenses 12 are held within the case 3 with their optical axes aligned with the rotation axis of the case 3.

The laser beam focused by the condensing lens 12 is reflected by the folding mirror 13 provided inside the tip of the case 3.
013a and is reflected in the right angle direction and led out through an opening 14 formed in the peripheral wall of the case 3.

When welding the joint portion between the outer tube 15 as a workpiece and the inner tube 16 fitted into the outer tube 15 from the inner circumferential surface using the laser processing device configured in this way, , the support body 1 is inserted into the outer tube 15, and the tip of the case 3 is positioned at the joint between the outer tube 15 and the inner tube 16. Next, a laser beam is made to enter the optical fiber 11, and the motor 7 is operated to rotate the case 3 simultaneously.

As a result, the laser light emitted from the tip of the optical fiber 11 is focused by the condenser lens 12, reflected by the reflection surface 13a of the folding mirror 13, and exits from the aperture 14 made in the case 3 and enters the interior. Look at the inner circumferential surface of the tube 16! 11, the overlapping portion of the inner tube 16 and the outer tube 15 can be welded.

By the way, in such a laser processing apparatus, since the end fiber 11 that transmits laser light is long, it is difficult to rotate the entire optical fiber 11. Therefore, even if the optical axes of the optical hyper 11 and the condensing lens 12 are aligned with the axis of the support 1 and the case 3 is rotated, the laser light emitted from the tip fiber 11 and the condensing lens 12 This prevents the optical axis from shifting.

However, according to such a configuration, the condenser lens 1
2 and the folding mirror 13 had to be installed on the central axis of the case 3, and there was no degree of freedom in installation. Therefore, since the focal length and convergence angle of the condenser lens 12 are determined by the inner diameter of the case 3, the bending mirror 1
The spot size of the laser beam on the reflective surface 13a of the case 3 or the spot size of the laser beam passing through the aperture 14 of the case 3 cannot be reduced, or the distance between the bending mirror 13 and the aperture 14 cannot be adjusted to the radius of the case 3. As a result, splash generated during welding may easily enter the case 3 through the opening 14.
It was said that it was easy to adhere to.

(Problems to be Solved by the Invention) As described above, in the conventional laser processing device, the condenser lens and the bending mirror 13 must be arranged to coincide with the central axis of the case 3, which reduces the degree of freedom in arrangement. Since the inner diameter of the case described above determines the focal length and convergence angle of the condensing lens, the spot size of the laser beam on the reflective surface of the bending mirror and the spot size that passes through the aperture are limited. That happened.

This invention was made based on the above circumstances, and its purpose is to provide a laser processing device in which the installation position of the condenser lens and bending mirror is not limited to the center of the case. It is about providing.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to solve the above problems, the present invention provides a support body in which an optical fiber insertion hole is formed in the center, and one end of the support body. a cylindrical case that is attached and driven to rotate coaxially with the insertion hole and has an opening on the peripheral side of the distal end side through which the laser beam passes; a first optical fiber pushed through the insertion hole; and the support. At one end of the body, place the rear end on a phantom surface coaxially with the above insertion hole, and turn around (1
: a second optical fiber attached to the case; a holding member provided in the case to hold the tip of the second optical fiber at a location non-coaxial with the insertion hole; and a holding member provided in the case mountain. It includes a condensing lens that condenses the laser beam emitted from the second optical fiber, and a folding mirror that folds back the laser beam condensed by the condensing lens in a direction in which it passes through the aperture.

With this configuration, the second optical fiber can be rotated together with the case without twisting, and the condenser lens can be placed at a position offset from the center of the case. You can freely set the focal length and convergence angle.

(Example) An example of the present invention will be described below with reference to FIG. The laser processing apparatus shown in FIG. 1 includes a shaft-shaped support 21. The laser processing apparatus shown in FIG. The tip of this support body 21 is formed into a narrow diameter portion 22, and the inner peripheral surface of the rear end of a cylindrical case 23 with a closed tip surface is rotated by a pair of first bearings 24 in the narrow diameter portion 22. freely supported. An internal gear 25 is provided on the rear end surface of the case 23, and a spur gear 26 meshes with the internal gear 25. This flat wheel 26 is fitted onto a rotating shaft 28 of a motor 27. The motor 27 is accommodated and held in a recess 29 formed in the support 21. Therefore, the motor 27 operates and l' i ? I'1.
When the gear 26 rotates, the case 23 is driven to rotate via the internal gear 25 meshed with the lock gear 26.

A first optical fiber 31 is pushed through the center of rotation of the support 21 . A laser beam enters the first optical fiber 31 from the rear end surface and extends from the distal end surface. The laser light emitted from the distal end surface of the first optical fiber 31 is transmitted to the first optical fiber 31, which is held in a accommodating portion 32 formed at the distal end of the support 21 with its optical axis aligned with the central axis of the support 21. The light is incident on the condensing lens 33. A rear end of a second optical fiber 35 is rotatably supported in the accommodating portion 32 by a second bearing 34 with its optical axis aligned with the optical axis of the first condensing lens 33 . This second optical fiber 35 is bent with a gentle curvature exceeding the bending limit,
The tip thereof is supported by a first holding member 36 protruding from the inner surface of the case 22 at a position eccentric from the center of the case 23, with the optical axis parallel to the central axis of the case 22.

On the distal end side of the second optical fiber 35, a pair of second condensing lenses 38, which are held by a second holding member 37 and have their optical axes aligned with the optical axis of the second optical fiber 35; Similarly, folding mirrors 39 whose optical axes are aligned with the optical axis of the second optical fiber 35 are sequentially arranged. Laser light that is emitted from the second optical fiber 35, focused by the second condensing lens 38, and reflected in the right angle direction by the reflecting surfaces 39a of the three folding mirrors is emitted through an opening in the peripheral wall of the case 23. 4
1 to the outside.

In the laser processing device configured in this way, the outer cylindrical tube 15 and
When welding the joint part with the inner tube 16 fitted into the outer tube 15 from the inner circumferential surface, the support 21 is compressed into the outer tube 15 and the tip of the case 23 is welded. The above outer tube 1
5 and the inner cylindrical pipe 16. Next, laser light is made to enter the first optical fiber 31, and the motor 27 is activated to rotate the case 23. Thereby, the laser light emitted from the tip of the first optical fiber 31 is focused by the first condensing lens 22 and enters the second optical fiber 35. The light then exits from the second end fiber 35, is focused by a pair of second condensing lenses 38, is reflected by the reflecting surfaces 39a of the three folding mirrors, and passes through the aperture 41 of the case 22. As a result, the inner circumferential surface of the inner cylindrical tube 16 is irradiated over its entire length with laser light, so that the inner cylindrical tube 16 and the outer cylindrical tube 15 can be laser pressurized, such as by welding.

By the way, in the laser processing apparatus having the above configuration, the first optical fiber 31 and the second optical fiber 35 are used as the optical path for guiding the laser beam to the three folding mirrors.
The rear end of the optical fiber 35 is rotatably supported at the tip of the support 21, and the tip is aligned with the optical axis of the second condenser lens 38. Therefore, the second optical fiber 35
Even if the tip of the second optical fiber 35 is held eccentrically from the center of the case 21, the case 21 can be rotated without twisting the second optical fiber 35. Fold back Mira~39 case 2
It can be arranged at an eccentric position within 3.

In other words, since the second optical fiber 35 can be curved into a single curve at a rate greater than or equal to the curvature limit radius, the second condensing lens 38 and the folding mirror 39 can be aligned within the range of the curvature. can be placed.

Therefore, since the focal length and convergence angle of the pair of second condensing lenses 38 can be set as desired, the spot size of the laser beam on the reflecting surfaces 39a of the three folding mirrors and the size of the laser beam perforated in the case 21 can be adjusted. The spot size of the laser beam passing through the aperture 41 can also be freely set. Thereby, for example, the spot size of the laser beam passing through the aperture 41 can be reduced, and the aperture 41 can also be made smaller in accordance with the spot size, so that the splash generated during welding can be transmitted from the aperture 41 to the case. 21 and the reflective surface 3 of the folding mirror 39
9a can be prevented from adhering to the inside of the case 21, and since the folding mirror 39 can be disposed at a position farther from the through hole 41 than the center of the case 21, this also allows for the return mirror 39 to be disposed at a position farther from the through hole 41 than from the center of the case 21. The splash that has entered the mirror is difficult to adhere to the anti-IlJ surface 39a of the three folding mirrors.

Furthermore, since the folding mirror 39 is eccentrically arranged in the direction away from the through hole 41, assuming that the converging angle of the second condensing lens 38 is the same as that of the conventional condensing lens, the folding mirror 39 Even if the spot size of the laser beam on the reflective surface 39a of the mirror 39 is made larger than before, the laser beam can be focused on the inner peripheral surface of the inner tube 6. Therefore, thermal damage to the reflective surface 3Qa of the folding mirror 39 from the laser beam can be reduced.

On the other hand, when it is desired to increase the spot size of the laser light in order to perform heat treatment such as hardening on the inner circumferential surface of the inner tube 16, the focal length and convergence angle should be adjusted according to the spot size. The condensing lens 38 may be used, and the aperture 41 formed in the case 21 may have a size corresponding to the spot size.

Furthermore, by decentering the folding mirror 39 in a direction approaching the aperture 41 of the case 21, the laser beam can be focused on the inner circumferential surface of the inner tube 16 using the second condensing lens 38 with a short focal length. Can be done.

Note that the present invention is not limited to the configuration of the above-mentioned embodiment; for example, the optical axis of the pair of second condensing lenses is aligned with the illumination of the case.
It does not have to be parallel to the central axis, and the angle at which the laser beam is bent by the bending mirror may be other than 90 degrees. Further, the mechanism for rotationally driving the case, the means for introducing laser light from the first optical fiber to the second optical fiber, etc. are not limited at all.

[Effects of the Invention] As described above, according to the present invention, there is a condenser lens that converges the laser light emitted from the second optical fiber through the first optical fiber, and Since the folding mirror that reflects the laser beam can be placed at a position offset from the center of rotation of the case, there are no restrictions on the focal length or convergence angle of the condensing lens. Therefore, since it is possible to reduce the spot size of the laser beam passing through the aperture formed in the case by reducing the convergence angle of the condensing lens, the aperture can also be made smaller accordingly, for example, for welding. This has the advantage that splash generated during processing can be prevented from entering the case and adhering to the reflective surface of the folding mirror.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an apparatus for laser processing the inner peripheral surface of a cylindrical workpiece, showing an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional apparatus. 21... Support body, 23... Case, 27... Motor (drive mechanism), 31... First optical fiber, 35...
...Second optical fiber 37...Second holding member, 3
8...Second condensing lens, 3...Folding mirror 4
1...Open hole.

Claims (1)

[Claims] A support body in which an optical fiber insertion hole is formed in the center, and an opening that is attached to one end of this support body and driven to rotate coaxially with the insertion hole, and that allows the laser beam to pass through the peripheral side of the tip side. A cylindrical case, a first optical fiber inserted into the insertion hole, and a second optical fiber rotatably attached to one end of the support with its rear end coaxially facing the insertion hole. a fiber, a holding member provided in the case to hold the tip of the second optical fiber at a location non-coaxial with the insertion hole, and a holding member provided in the case to emit light from the second optical fiber. A laser processing device comprising: a condenser lens that condenses laser light; and a folding mirror that redirects the laser beam condensed by the condenser lens in a direction in which it passes through the aperture.