JPS5933076B2 - Laser processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser processing device equipped with an automatic focusing mechanism.

FIG. 1 shows a conventional laser processing device equipped with an automatic focusing mechanism.

That is, the workpiece 4 on the stage 3 is irradiated with laser light from the laser oscillator 1 using the condenser lens 2 to process the workpiece. At this time,
By arranging the half mirrors 6 and 8, parallel light rays L from the light source 7 are generated.
The workpiece is irradiated with 4 VC, and the reflected light 2 enters the detector 9 VC. The detector 9 detects the output difference of the reflected light 1 which varies depending on the position of the workpiece 4 with respect to the focal position of the condenser lens 2, and the output difference is sent to the control mechanism 11 via the amplifier 10. The focus position was set by operating the drive mechanism 5 to move the stage 3 up and down in accordance with an increase or decrease in the output difference. However, this device has a complicated optical system, and when processing with a high-power laser, plasma etc. are generated, and the irradiated laser light is absorbed, scattered, etc. by this plasma, and reaches the detector 9. The problem was that the amount of reflected light that entered the camera changed, resulting in it being detected as being out of focus even though there was no shift in focus. Further, there were drawbacks such as difficulty in moving the stage depending on the size of the workpiece. There is also a method of measuring the change in distance from the workpiece using an air micrometer to set the focus, but this method has the disadvantage that it cannot be used in a vacuum. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a laser processing apparatus that can detect the position of a workpiece regardless of its surface condition.
Another object of the present invention is to provide a laser processing apparatus which can be operated in a vacuum without any inconvenience, and which has an automatic positioning mechanism with a simple structure. The present invention detects a change in the position of the workpiece surface in the direction of the laser optical axis by detecting a change in inductance due to an eddy current generated on the workpiece surface or a capacitance change between the workpiece surface and the inductance or electric current. This is a laser processing device in which the condenser lens or the condenser lens is moved along with the detector in the direction of the laser optical axis so that the capacitance is constant, and the focus of the condenser lens is made to coincide with the surface of the workpiece.

Embodiments according to the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the laser processing apparatus of the present invention, in which, for example, high-power CO
The two laser beams are condensed and irradiated by a condenser lens 2 onto the surface of a metal workpiece 4 fixed on a stage 3 .

At this time, the distance between the detector 12 and the workpiece 4, that is, the distance between the condenser lens 2 and the workpiece 4, is determined by the detector 12 that is installed integrally with the condenser lens 2 and detects changes in inductance or capacitance. is detected, and as this distance changes, detector 1
When the output by 2VC changes, the control device 11Vc
Therefore, the drive mechanism 5 is driven so that the distance between the detector 12 and the workpiece 4 becomes a set value, so that the detector 12 and the condenser lens 2 are at a constant distance from the surface of the workpiece 4. . As described above, the focus of the objective lens of the processing device can always be automatically set on the surface of the workpiece 4.

In particular, since the workpiece 4 has a flat surface made of a metal material, the position of the workpiece 4 can be accurately measured by a detector that detects changes in inductance or capacitance. Next, FIG. 3 shows another embodiment.

This may be done in a low pressure atmosphere or in another atmosphere, for example N2
, O2, and Ar.

The laser beam oscillated by the laser oscillator 1 passes through the condensing lens 2
Casing 1 for concentrating the light and maintaining the processing atmosphere
Window 1 transparent to the wavelength of the laser light attached to 4
3 and irradiates the surface of the workpiece 4 placed on the stage 3 for processing. At this time, the distance between the detector 12 and the surface of the workpiece 4 is detected by the detector 12 that detects changes in the inductance or capacitance fixed to the casing 14VC, and the detector 12' detects the distance between the detector 12 and the surface of the workpiece 4. Detect location. By the way, if the surface of the workpiece placed in the casing 14 is detected by the detector 12 whose inductance or capacitance changes, it is possible to accurately detect the surface position of the workpiece without being affected by the processing atmosphere. can. When the surface of the workpiece 4 changes in the laser optical axis direction, the amount of change is detected by the detector 12, and the condenser lens 2
The drive mechanism 5 is driven by the control mechanism 11 to move the lens position until the output from the detector 12/ detecting the position shows the same amount of change as the above amount of change. Detector 1
The outputs of the detector 12 and the detector 121 can be directly compared by using the same thing as the detector 2 and the detector 12', or by calibrating them so that the outputs for the amount of change are the same. By simply controlling the position of the condensing lens 2 so that both outputs are always equal, it is possible to automatically focus on the surface of the workpiece 4. Next, another embodiment will be described with reference to FIG. 4 (although initial settings are necessary).

This is a processing device for performing dynamic balancing using a laser. Laser light emitted from a laser oscillator 1 is focused and irradiated onto a rotating body 15, which is a workpiece, by a condensing lens 2. The rotating body 15 is housed in a casing 16 for maintaining a processing atmosphere or for safety, and the laser beam is irradiated through a window that transmits the wavelength of the laser beam. Also, the rotating body 15VC. A phase detection mechanism 17 for detecting the phase of the rotating body 15 is installed, and a laser control device 18 allows irradiation to a fixed location even when the rotating body 15 is rotating at high speed. A detector 12 fixed to the casing 16 detects changes in the position of the processing portion of the rotating body 15. The control mechanism 1 is operated so that the position output of the part to be processed is equal to the output of the detector 12' that detects the position of the condensing lens 2.
1VC drives the drive mechanism 5 to move the lens position. As shown in FIG. 4, consider the case where the processing section and the detection section are shifted by 180 degrees.

When rotating the rotating body 15, which has a disc attached to a thin shaft, the speed near the critical speed is several M depending on the amount of eccentricity.
It vibrates with an amplitude of m. FIG. 5 shows an example in which the output of the detector 12 in that case is converted into displacement. However, in the machining section, the phase should be shifted by 180 as shown in FIG.
It is necessary to shift it by 800. Here, the displacement X in FIGS. 5 and 6.

is, for example, the focal position of the condenser lens when the object is at rest. Here, when removing the unbalance by oscillating the T, VC laser shown in Figure 6, the phase of the output of the detector 12 is determined by referring to the output of the phase detector 17 and the phase of the output of the detector 12 is calculated by referring to the output of the phase detector 17. The lens position is detected by the detector 12' and moved by an amount corresponding to the output when shifted by 180 degrees.

Then, laser irradiation may be performed in synchronization with the phase of laser processing. As described above, when it comes to dynamically balancing the rotating body, simply by setting the phase of laser irradiation, the focus can be automatically adjusted to the surface of the processed part. As explained above, the present invention has the following effects.

(1) There is no need for an optical system for focusing, making the device simple and inexpensive.

(2) Focusing can be performed while eliminating the effects of plasma and the like caused by high-power laser processing.

(3) Can be used regardless of the processing atmosphere.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a laser processing device according to the prior art;
4 are schematic diagrams showing respective embodiments of the laser processing apparatus according to the present invention, and FIG. 5 is a diagram showing a waveform converted into an output waveform displacement by the detector of the embodiment Vc shown in FIG. 4,
FIG. 6 is a diagram showing a displacement waveform of the processing section VC. Explanation of symbols, 1... Laser oscillator, 2...
・・Condensing lens, 3・・・・Product table, 4・・・・・
・Workpiece, 5... Drive mechanism, 11...
- Control mechanism, 12...detector.

Claims (1)

[Claims] 1. A condensing lens that condenses the irradiated laser beam is provided,
In a laser processing device that laser-processes a workpiece using a laser beam focused by the condenser lens, a laser beam is attached to the workpiece surface so as to detect the position of the workpiece surface in the laser optical axis direction. A detector for detecting a change in inductance due to the generated eddy current or a detector for detecting a change in capacitance with the surface of the workpiece is provided, and a drive mechanism for moving the condensing lens in the direction of the laser optical axis is provided. A laser processing apparatus characterized in that the drive mechanism is driven by the output of the detector so that the focal position of the condensing lens always coincides with the surface of the workpiece. 2. The laser processing device according to claim 1, characterized in that the condenser lens and the detector are integrated. 3 Provide a condensing lens that condenses the irradiated laser beam,
In a laser processing device that laser-processes a workpiece using a laser beam focused by the condenser lens, a casing for placing the workpiece in a predetermined atmosphere is provided, and an eddy current is applied to the casing. A detector is installed to detect the distance between the workpiece and the workpiece by changes in inductance or capacitance caused by the change in inductance, and the condenser lens is moved in the direction of the laser optical axis according to the output of the detector that detects the position of the condenser lens. A driving mechanism is provided to move the condenser lens according to changes in the position of the workpiece detected by the detector, so that the focus of the condenser lens always matches the surface of the workpiece. Laser processing equipment that is characterized by: 4 Provide a condensing lens that condenses the irradiated laser beam,
In a laser processing device that laser-processes a workpiece using a laser beam focused by the condenser lens, the workpiece is formed of a rotating body, and a detector detects fluctuations on the surface of the workpiece. and a phase detector for detecting the rotational phase of the workpiece, and a drive mechanism for moving the position of the condensing lens in the laser optical axis direction in accordance with the output of the detector for detecting the position of the condensing lens. The drive mechanism is controlled according to the output from the detector to focus the condensing lens on the surface of the laser irradiation part, and the rotational phase of the workpiece is synchronized based on the signal from the phase detector. A laser processing device characterized in that it irradiates laser light while