JPH1043877A - Laser beam mechanical condenser for laser spot welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly simplify the work by dispensing with a conventional expensive optical system as well as troublesome adjustment of the system and merely connecting a laser beam mechanical condenser to the end of a GI optical cable. SOLUTION: In a laser spot welding machine which performs welding by enhancing close contactness of objects 25, 26 to be welded, in a pressurized state by a welding head equipped with a pressurizing mechanism, with a laser beam for propagating an optical fiber cable 50; with a grated index type used for the optical fiber cable 50, attached to the machine is a laser beam mechanical condenser 53, which is fitted to the tip end of the cable, which is a hollow tubular shape inside so that a laser beam emitted from the end face of the optical fiber cable can propagate continuously through the inner face, and which is provided with such a length as the continuous beam waist generating by the continuous refraction of the laser beam is produced at the outgoing port tightly making contact with the object to be welded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light mechanical condensing section used in a laser spot welding machine for welding a workpiece such as a lead wire to a printed wiring board or the like by using a laser beam.

[0002]

2. Description of the Related Art Some conventional laser spot welding machines are constructed as shown in FIGS. Hereinafter, this will be described. 1 is the frame of the welding head 1 ',
Reference numeral 2 denotes a pressure barrel which is slidably movable up and down via a push 3 fixed to the frame 1. Reference numeral 4 denotes a pressure shaft, which is disposed in contact with the lower end of a pressure spring 7 built in the pressure barrel 2, and one end of a support arm 30 is attached to the lower end. Reference numerals 6 and 6 'denote slide bearings for supporting the pressurizing shaft 4 and for smoothly moving the pressurizing shaft 4 up and down.

Reference numeral 8 denotes a knob for determining the pressing force applied to the adapter 31 of the laser light emitting lens unit 5 attached to the other end of the support arm 30. By rotating this knob 8, The pressure applied to the adapter 31 is determined by the pressure spring 7 moving up and down via the pressure adjustment screw 9 that is linked to this. Reference numeral 10 denotes a pressure scale for displaying a pressing force applied to the pressure spring 7 by rotating the knob 8.

A yoke 11 is fixed to the pressurizing shaft 4, and is configured to work together with the shaft 12 and the pressurizing shaft 4 in the vertical direction.
Reference numerals 13 and 13 'denote slide bearings for causing the shaft 12 for rotation to smoothly move up and down.

Reference numeral 14 denotes a switch which operates when the applied pressure reaches a set value. The switch 14 uses a microswitch for detecting the applied pressure (hereinafter, referred to as a microswitch for detecting the applied pressure). The upper part of the arm 1 is fixed to the pressure barrel 2 by the support arm 15 and is activated when the pressure of the adapter 31 reaches a set value. This electric signal is transmitted via the cable 22. The laser light is transmitted to a power supply unit 21 having a built-in laser oscillator, and the laser light from the laser oscillator is supplied to a laser light emitting lens unit 5 via an optical fiber cable 23.

Reference numeral 16 denotes a microswitch 14 for detecting a pressing force.
Reference numeral 17 denotes a nut for adjusting the position of the contact 16. 1
An arm 8 has a yoke storage chamber 34 for the yoke 11, one end of which is attached to the pressure barrel 2 by screws 19, and the other end of which is mounted on the frame 1 by slide bearings 28, 28 '. , And is screwed to a drive shaft 29 which is slidably inserted through.

Reference numeral 20 denotes a return spring for returning the arm 18 to its original position when the arm 18 is pulled down. Reference numeral 21 denotes a power supply unit, which uses a YAG laser or the like as a built-in laser oscillator.

The lower end of the drive shaft 29 is connected to a drive source 33, and no excessive force is applied to the laser light emitting lens unit 5 via the arm 18 above the drive shaft 29. As shown, a stopper 2 such as a double nut
7 is provided to prevent the lowering from being performed more than necessary.

Reference numeral 24 denotes a connector of the optical fiber cable 23, and reference numerals 25 and 26 denote workpieces. One end of the support arm 30 is supported by the pressure shaft 4, and the other end thereof is provided with a laser light emitting lens unit 5. Is configured to move up and down.

The adapter 31 is mounted so as to protrude to a length substantially equal to the focal length of the lens of the laser light emitting lens unit 5, is formed hollow, and has a section Y made of aluminum or copper. The tip is disposed so as to abut against the workpieces 25 and 26. Therefore, the welding head 1 'has a pressing mechanism composed of the pressure barrel 2, the pressing shaft 4, the detent shaft 12, the pressing spring 7, the return spring 20, the arm 18, and the driving shaft 29. Is built-in.

Therefore, the laser light from the laser oscillator built in the power supply unit 21 is guided by the adapter 31 and the light beam is focused at the tip, so that the optical fiber cable 23 At the time of replacement, troublesome optical axis adjustment is not required, and the workpieces 25 and 26 can be reliably heated with laser light.

Reference numeral 32 denotes a table on which the workpieces 25 and 26 are placed, which is attached to the main body of the drive source 33 of the welding head 1 '.

With this construction, the workpieces 25 and 26 are first placed on the table 32, and then the arm 18 is pressed against the return spring 20 via the drive shaft 29. When the pressure barrel 2 is pulled downward, the pressure barrel 2 is fixed to the arm 18 by screws 19,
8, the pressure barrel 2, the pressurizing shaft 4 and the detent shaft 12 are integrally lowered.

When the tip of the adapter 31 comes into contact with the workpiece 25, the pressurizing shaft 4 and the detent shaft 12 stop descending, but the pressure barrel 2 and the arm 18 continue descending, and the yoke is stored. Yoke 11 in chamber 34
The pressure spring 7 is compressed until the gap L between the arm and the arm 18 becomes zero.

On the other hand, if a gap L ', which is slightly smaller than the gap L, is set as a gap between the pressure sensing microswitch 14 and the contact 16 by the position adjusting nut 17, the pressure barrel is set immediately before the gap L = 0. The pressure barrel 2 descends against the vertical movement of the rotation stopper 2 and the detent shaft 12, ie, the repulsive force (pressure) of the pressure spring 7, and the pressure sensing microswitch 14 and the contact 16 come into contact with each other. Then, the pressure sensing microswitch 14 operates.

At this time, if the gap L = 0, no extra pressure is applied to the pressure sensing microswitch 14 any more, so that this switch is not damaged. Further, if the gap between the stopper 27 and the frame 1 is adjusted by moving the stopper 27, the lowering of the arm 18 and the pressure barrel 2 is stopped, and an excessive pressure is applied to the laser light emitting lens unit. 5, and the workpieces 25 and 26 are not damaged.

When the pressure sensing micro switch 14 is operated, a signal is sent via the cable 22 to the power supply unit 21.
And the laser oscillator is excited to cause the laser light to enter the laser light emitting lens unit 5 via the optical fiber cable 23, and this laser light is guided by the adapter 31. The workpieces 25 and 26 on the table 32 are irradiated while being welded, and the welding is completed.

At this time, since the laser light emitting lens unit 5 and the adapter 31 are supported by the support arm 30, the laser light is stably adhered to the workpieces 25 and 26 by the adapter 31. Irradiation and welding are always performed at the same focal length, so that the laser light amount is always constant and a stable welding state can be obtained.

As shown in FIG. 7, a laser beam 41 emitted from an emission optical system 40 constituted by combining an optical system lens is provided at the end of an optical fiber cable 23.
The output optical system 4 is focused on the workpieces 25 and 26 so as to be focused.
8, and a capillary 43 attached to a capillary holder 42 to separate the capillary 4 from the workpieces 25 and 26, as shown in FIG.
There is also a type in which welding is performed in a state where 3 is separated.

[0020]

Since the conventional one is constructed as described above, any type of the laser light emission lens unit 5 or the emission optical unit 5 which is constructed by combining optical lenses is expensive. Since the system 40 is used, there is a problem that the apparatus becomes more expensive. Further, it is necessary to strictly adjust the focal length and the optical axis of the exit lens of the optical system, and such an optical adjustment is troublesome.

In the case of the welding type shown in FIG. 7 using the laser beam 41, the laser beam 41, which is a non-contact heat source, is applied to the workpieces 25 and 26 for welding. Problem.

[0022]

SUMMARY OF THE INVENTION According to the present invention, a laser beam from a laser oscillator propagating through an optical fiber cable is used to press a workpiece to be welded in close contact with a welding head provided with a pressing mechanism, and to apply a laser beam. In a laser spot welding machine that performs welding by irradiating a laser beam, the optical fiber cable uses a graded index type that propagates around the central axis of the core of the optical fiber cable by continuous refraction of the laser light. Fitted to the end of a Ted-index type optical fiber cable, the end of this cable is hollow, and the inside is a hollow cylinder, so that the laser beam emitted from the end of the graded-index type optical fiber cable can propagate continuously through the inner surface In addition, the continuous waist (beam waist) generated by the continuous refraction of the laser light adheres to the workpiece That it is obtained by way mount the laser light mechanical focusing portion having a length such that occurs in the exit port.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to FIGS.
It will be described in detail based on. FIG. 1 shows an embodiment of the present invention. FIG. 2 is a front view of a main part of a laser beam mechanical condensing section 53, FIG. 2 is an enlarged view of a portion A in FIG. 1, and FIG. FIG. 4 is a perspective view of a laser spot welder using a GI optical fiber cable 50.
FIG. The same components as those in the conventional example have the same names and the same reference numerals, and a description thereof will be omitted.

In FIGS. 1 to 3, reference numeral 50 denotes a graded index type optical fiber cable (hereinafter referred to as a GI type optical cable), and as shown in FIG.
Is refracted continuously and the core 5 of the GI optical cable 50 is
The laser beam 51 propagates around the core center axis 50c of 0a, and a continuous waist 52 occurs due to continuous refraction of the laser beam 51. 50b is a clad. In this embodiment, a core having a diameter of 600 μm is used.

Reference numeral 53 denotes a laser light mechanical condensing portion which is formed of a member such as ceramic, ruby, or sapphire, and is attached to the tip of the GI optical cable 50. And an outer diameter R is formed in a fixed cylindrical shape.
Further, the length of the laser light mechanical focusing section 53 is GI
The laser beam 51 emitted from the end face of the optical fiber cable 50 is continuously propagated on the inner surface, and the beam waist 52 of the laser beam 51 has an emission port 53a in close contact with the workpieces 25 and 26.
, And the tip is attached so as to abut against the workpieces 25 and 26.

For example, when the inner diameter r of the GI optical cable 51 is 700 μm, the length L of the laser light mechanical focusing section 53 is 5 mm.
Below, preferably 2-3 mm, the emission aperture t is 100 μm
Hereinafter, it is preferably formed to be 50 μm and the outer diameter R to be about 2 to 3 mm.

Reference numeral 54 denotes a holder for the laser light mechanical condensing section 53, which holds the GI optical cable 50 and the laser light mechanical condensing section 53 in a state where they are connected to each other.
This is for fixing to the movable arm 30. This holder 5
4, a through hole 5 through which the GI optical cable 50 penetrates.
4c, a fastening portion 5 for fixing the GI optical cable 50 penetrating therethrough to the holder 54 at the upper end.
4a, and a mounting portion 54b for mounting the laser beam mechanical focusing portion 53 is provided at the lower end. Accordingly, the holder 54 is attached to the support arm 30 and is configured to move up and down while supporting the laser beam mechanical light condensing unit 53 by the vertical movement of the pressure shaft 4.

With such a structure, as shown in FIGS. 4 and 6, the workpieces 25, 26
When the arm 18 is pulled down via the drive shaft 29, the four members of the pressure barrel 2, the pressurizing shaft 4 and the detent shaft 12 are integrally lowered with the lowering of the arm 18.

When the tip of the laser beam mechanical condensing portion 53 comes into contact with the workpieces 25 and 26, the pressure shaft 4 and the detent shaft 12 stop descending, but the pressure barrel 2 and the arm 18 further move. When the lowering is continued and the pressure sensing microswitch 14 and the contact 16 come into contact with each other, the pressure sensing microswitch 14 operates.

When the pressure sensing microswitch 14 is operated, this signal is transmitted to the power supply unit 21 via the cable 22 to excite the laser oscillator, and as shown in FIG. The optical cable 50 is continuously refracted, propagates around the core central axis 50c of the core 50a, and directly enters the laser light mechanical condensing section 53. At this time, the continuous beam waist 52 due to the continuous refraction of the laser light 51 propagating through the GI optical cable 50.
Has occurred. The shape of the laser light mechanical condensing portion 53 is formed so that the beam waist 52 is generated at the output port 53a of the laser light mechanical condensing portion 53, so that the laser beam 51 converged at the output port 53a is welded. The objects 25 and 26 are irradiated, and the welding is completed.

At this time, since the laser beam mechanical focusing section 53 is supported by the support arm 30, the workpiece 25,
26 is irradiated with the laser beam 51 in a stable close contact state, and the beam waist 52 is always irradiated and welded, so that the laser light quantity is always constant and a stable welding state is obtained.

[0032]

According to the present invention, the object to be welded is pressed by a laser head from a laser oscillator propagating through an optical fiber cable while being pressed by a welding head equipped with a pressing mechanism, and the laser beam is irradiated. In a laser spot welding machine for welding, an optical fiber cable uses a graded index type in which the laser beam propagates around the central axis of the core of the optical fiber cable by continuous refraction. At the end of the fiber cable, it is fitted to the end of this cable, the inside is hollow cylindrical, and the laser light emitted from the end face of the graded index type optical fiber cable can continuously propagate on the inner surface. The continuous waist (beam waist) generated by the continuous refraction of the laser beam is generated at the exit that is in close contact with the workpiece. Because fitted with a laser beam mechanical focusing portion having so that length, without the need to use conventional expensive optical system such as, Moreover, there is no need to adjust the cumbersome optics. Simply connecting the laser light mechanical condensing part to the end of the GI optical cable suffices and the operation becomes very simple.

In addition, since an appropriate pressure is applied to the workpiece through the laser beam mechanical condensing portion which is good for the welding head, the workpiece can be stably adhered to the welding head. As a result, the laser beam at the beam waist is irradiated, welding can be reliably performed, and a stable welding state can be obtained.

In the laser beam mechanical focusing section,
Since the laser light propagates while being refracted in the air in the through-hole, the output of the laser light is not attenuated as compared with a conventional one that propagates in a solid such as a capillary.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a front view of a main part of a laser beam mechanical focusing section 53.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 shows an embodiment of the present invention and is a perspective view of a laser spot welding machine using a laser light mechanical focusing section 53.

FIG. 4 is a cross-sectional view of the GI optical cable 50.

FIG. 5 is a perspective view of a conventional laser spot welding machine.

FIG. 6 is a sectional view of a main part of a conventional laser spot welding machine.

FIG. 7 is a main part front view showing another conventional example.

FIG. 8 is a front view of a main part showing another conventional example.

[Explanation of symbols]

 1 'Welding head 21 Power supply unit incorporating laser oscillator 25, 26 Workpiece 29 Drive shaft 30 Support arm 50 GI optical cable 50c Core center axis of GI optical cable 50 51 Laser light 52 Beam waist of laser light 51 Laser light Mechanical condensing part 53a Outlet of laser light mechanical condensing part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location // H01S 3/101 H01S 3/101

Claims (1)

[Claims] 1. A laser for performing welding by applying a laser beam from a laser oscillator propagating through an optical fiber cable to a welding head equipped with a pressing mechanism, in which the workpiece is pressurized and brought into close contact with the welding head. In the spot welding machine, the optical fiber cable uses a graded index type which propagates around a central axis of the optical fiber cable by continuous refraction of laser light. The laser light emitted from the end of the graded-index type optical fiber cable can be continuously propagated through the inner surface of the optical fiber cable. A continuous waist (beam waist) generated by continuous refraction of light is generated at an exit port that is in close contact with the workpiece. A laser beam mechanical focusing section of a laser spot welding machine, wherein a laser beam mechanical focusing section having such a length is mounted.