JPS6245034B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic focus tracking device for a laser device that maintains an optimum distance between a condensing lens that condenses a laser beam and a workpiece.

Conventionally, various focus adjustment devices have been proposed that adjust the distance between the condenser lens and the workpiece to obtain the optimal focal length of the laser beam, and generally, the condenser lens is fixed. The gap between the focus head and the workpiece is detected using a non-contact detector or a contact detector, and the focus head is moved up and down so that the detected value remains constant. The distance between them is kept constant.

By the way, in order to obtain an accurate focal length, it is desirable to measure the above-mentioned gap at the irradiation position of the laser beam, but since plasma is generated by the laser beam at that position, measurement is difficult and errors are likely to occur. Generally, measurements are made at a position slightly distant from the irradiation position. However, if the irradiation position of the laser beam and the measurement position are different, for example, if the processing surface of the workpiece is sloped or uneven, the focus head may be controlled to an inaccurate position. It was hot.

In view of such circumstances, the present invention comprises the above-mentioned focus head consisting of an elevating member that is raised and lowered by an elevating mechanism and a nozzle member provided on the elevating member so as to be able to rise and fall freely, and the above-mentioned condensing lens is attached to the nozzle member. At the same time, the tip of the nozzle member can be brought into contact with the workpiece, and the focal position of the laser beam by the condensing lens is made to substantially coincide with the tip portion of the nozzle member that contacts the workpiece. To provide an automatic focus tracking device for a laser device that can move up and down while being in contact with the processing surface of a workpiece, and at the same time can always maintain an optimum focal length even when a nozzle member goes up and down. be.

The present invention will be described below with reference to the illustrated embodiment. In the figure, a focus head 1 that irradiates a laser beam L is movable up and down toward a workpiece 4 along a guide rod 3 provided on a support frame 2. . The support frame 2 is provided with an elevating mechanism 5 for elevating and lowering the focus head 1. In the illustrated embodiment, the elevating mechanism 5 includes a motor 6 and a vertical screw shaft 7 that is rotated forward and backward by the motor 6. The screw shaft 7 is screwed into the focus head 1 so that the focus head 1 can be moved up and down.

The support frame 2, which supports the focus head 1 in a vertically movable manner, can move forward and backward along a guide member 9 provided horizontally on the machine frame 8 so as to be orthogonal to the screw shaft 7. It is adapted to be moved in that direction by a drive mechanism similar to that of . The workpiece 4 is placed on a table (not shown), and is movable by the table in a direction perpendicular to the screw shaft 7 and the guide member 9, respectively.

Accordingly, the focus head 1 has an elevating member 10 that engages with the guide rod 3 and the screw shaft 7.
and a cylindrical portion 1 formed at the bottom of this elevating member 10.
1 and a nozzle member 13 which is provided so as to be movable up and down via a bearing 12, and the nozzle member 13
is always urged downward by the elastic force of the springs 14 and 15, and the dead weight of the nozzle member 13 and the spring 14,
15 allows the nozzle member 13 to be brought into pressure contact with the workpiece 4 with a predetermined light urging force. The interior of the nozzle member 13 is communicated with an assist gas supply source (not shown) via a conduit 16 connected thereto.

Further, a condensing lens 20 for condensing the laser beam L is attached to the upper end of the nozzle member 13, and the outer peripheral surface of the lower end of the nozzle member 13 is formed into a conical shape, and the tip thereof is attached to the workpiece 4. The laser beam L is made contactable and the lower end shaft part is
A hole 21 is formed to allow the passage of. The focal position of the laser beam L by the condensing lens 20 is adjusted to be suitable for laser processing the workpiece 4 while the nozzle member 13 is in contact with the workpiece 4. It is set in a certain position. This focal point position varies somewhat depending on the material, thickness, etc. of the workpiece 4, but generally it is approximately at the opening edge of the hole 21 to the outside.

Furthermore, this elevating member 10 is attached to the elevating member 10.
A main body 23 of a detector 22 for detecting the vertical position of the nozzle member 13 with respect to the main body 23 is attached, and a detector 24 of the detector 22 is connected to the nozzle member 13 via a connecting member 25. This detector 22 is designed to be able to detect the position of the detector 24 with respect to its main body 23, and therefore the vertical position of the nozzle member 13 with respect to the vertical movement member 10.
A signal from the controller is inputted to a control device 26 such as a microcomputer. This control device 26 controls the lifting mechanism 5 in response to a signal from the detector 22.
It is possible to maintain the vertical position of the nozzle member 13 with respect to the vertical movement member 10 at a predetermined vertical position.

In the above configuration, in the non-operating state, the focus head 1 is located at the ascending end, and the nozzle member 13 is located at the descending end position with respect to the elevating member 10 due to its own weight and the elastic force of the springs 14 and 15. ing. Therefore, the detector 2 of the detector 22 is also connected to the nozzle member 13 via the connecting member 25.
4 is also located at the lower end position.

When a command to start operation is given to the control device 26 from this state, the control device 26 controls the lifting mechanism 5 to lower the focus head 1, so that when the lower end of the nozzle member 13 comes into contact with the workpiece 4, Although the nozzle member 13 stops descending, the elevating member 10 continues to descend.

As a result, the nozzle member 13 is raised relative to the elevating member 10, and when the elevated position of the nozzle member 13 relative to the elevating member 10 reaches a predetermined position, the control device 26 detects this using the detector 22. Detected through. When the control device 26 detects that the nozzle member 13 has reached a predetermined height position, the control device 26 stops the descent of the elevating member 10 by the elevating mechanism 5, and then directs the laser beam L to the workpiece 4. Aim the target and start laser processing.

During the laser processing described above, even if the workpiece 4 is tilted or uneven and the nozzle member 13 is moved up and down with respect to the elevating member 10, the condenser lens 20 cannot be moved to the nozzle. Part 1
3, the focal position of the condenser lens 20 will not be displaced from the opening edge of the hole 21 as the nozzle member 13 moves up and down, and smooth laser processing can be continued. At this time, since the nozzle member 13 itself that irradiates the laser beam L is in contact with the workpiece 4, the irradiation position of the laser beam L and the measurement position of the focal point substantially coincide, so that the above-mentioned Even if the processing surface of the workpiece 4 is inclined or uneven, highly accurate laser processing can be performed at all times.

Then, the nozzle member 13 for the elevating member 10
If the amount of elevation increases and exceeds the allowable range, the control device 26 detects this via the detector 22 and controls the elevation mechanism 5 to raise and lower the elevation member 10. The position of the nozzle member 13 with respect to the member 10 is always maintained within a predetermined range.

In the above embodiment, the biasing direction of the pair of springs 14 and 15 is downward, but either one or both may be omitted if necessary, and the self-weight of the nozzle member 13 is It may be made to oppose. Further, although the present invention has been described based on the upward and downward directions for convenience, it is needless to say that the present invention is not limited to this.

As described above, according to the present invention, it is possible to obtain the effect that the irradiation position of the laser beam and the measurement position are substantially the same, and the optimum focal length can always be ensured.

[Brief explanation of the drawing]

The figure is a sectional view showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Laser nozzle, 4... Workpiece, 5... Lifting mechanism, 10... Lifting member, 13... Nozzle member, 20...
Condensing lens, L...laser beam.

Claims (1)

[Claims] 1. In a laser device in which a focus head that is raised and lowered by a lifting mechanism is provided with a condenser lens, and a laser beam focused by the condenser lens is irradiated from the focus head to a workpiece, the focus head is moved by the lift mechanism. It is composed of an elevating member that can be raised and lowered by moving up and down, and a nozzle member that is provided on this elevating member so that it can be raised and lowered.The condensing lens is attached to the nozzle member, and the tip thereof can be brought into contact with the workpiece, and the condensing lens is An automatic focus tracking device for a laser device, characterized in that a focal position of a laser beam by a lens is made to substantially coincide with a tip portion of the nozzle member that contacts a workpiece.