JPH0429477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a distance measuring device for a laser processing device that uses laser light to detect displacement of an object from a reference plane in laser processing.

[Conventional technology]

Figure 2 shows a cross section of this type of device described in Japanese Patent Application No. 59-227226. In the figure, 1 is a processing laser beam, 2 is a processing lens that focuses the processing laser beam 1, and 3 is a processing lens that focuses the processing laser beam 1. A processing head, 4 is a light source that emits a beam as a measuring laser beam made of a semiconductor laser, 5 is a projection lens that focuses the beam emitted from the light source 4, and 6 is an image of the radiation beam on the surface of the object W1. 7 is a position detection element (Position Sensitive Detector, hereinafter referred to as PSD) that generates an electric signal according to the imaging position of the radiation beam image, 8 is a displacement detection current output from PSD 7
By performing predetermined calculations based on Ia and Ib, the object W1 is
an arithmetic processor for calculating the displacement from the reference surface S;
is a distance control device that performs control to position the object W1 within a predetermined distance range with respect to the reference plane S according to the calculation result of the calculation processor 8.

Next, the operation will be explained. The beam emitted from the light source 4 becomes a light spot of an appropriate size by the projection lens 5, and is irradiated onto the surface of the object W1. The light receiving lens 6 images this light spot,
A light spot image is formed on the light receiving surface of the PSD 7.
The PSD 7 generates electrical signals Ia and Ib according to the imaging position of the optical spot image. The arithmetic processor 8 calculates the displacement of the object W1 from the reference plane S based on the displacement detection currents Ia and Ib. The distance control device 9 receives the calculation result and controls the position of the machining head 3 according to the calculation result.

First, when the surface of the object W1 is on the reference plane S, the light input to the light receiving lens 6 is irradiated onto the PSD 7 as a spot of light. When the surface of the object W1 is on the reference plane S, the center of gravity of this light is PSD
7, the displacement detection currents 1a and 1b become equal to each other. The arithmetic processor 8 inputting the displacement detection currents Ia and Ib outputs the displacement as 0 to the distance control device 9. This causes the distance control device 9 to keep the machining head 3 in the same position.

Next, when the surface of the object W1 is displaced downward by ΔH, the light scattered on the surface of the object W1 passes through the light receiving lens 6 and then enters the point P2, which is ΔX away from the center P1 of the PSD 7, in the form of a spot. be done. Displacement detection currents Ia and Ib are output by this incident light, but
The displacement detection currents Ia and Ib have different values.
Since ΔH and ΔX are in a proportional relationship, ΔH can be calculated and output by calculating ΔX.
In response to this output signal, the distance control device 9 lowers the machining head 3 so that the displacement ΔH becomes zero, for example. In this way, the distance between the processing head 3 and the surface of the object W1 is always kept within a certain predetermined range.

[Problem that the invention seeks to solve]

Conventional distance measuring devices for laser processing equipment are configured as described above, so if the distance between the processing head and the surface of the object changes, the position of the light spot output from the distance measurement light source changes to the position of the processing laser. Since the object moves to a point ΔE away from the center of the optical axis, the object has a curved surface, and the light spot is formed at a different position on the curved surface than when the object is flat. There were problems in that the distance to a point could not be measured correctly, and a separate light source for distance measurement was required, leading to a complicated device configuration.

This invention was made in order to solve the above-mentioned problems, and its purpose is to obtain a distance measuring device for a laser processing device that can measure a distance by using the same position as a processing point as a distance measurement point. do.

[Means for solving problems]

The distance measuring device for laser processing equipment according to the present invention includes:
When the displacement of the surface of the object from the reference plane is measured using the measuring laser beam, the processing laser beam is also used as the measuring laser beam.

[Effect]

Since the distance measuring device for laser processing equipment according to the present invention uses a processing laser beam as the measurement laser beam, the object is heated by the processing laser beam reflected from the object surface and the energy of the processing laser beam. The light from the object can be selectively used for measurement, there is no deviation between the measurement point on the object surface and the processing point, improving measurement accuracy, and it is also possible to measure the distance to the object surface with curvature. High accuracy can be achieved, and a separate light source for distance measurement is not particularly required.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, parts with the same symbols as in FIG. 2 are the same as those in the conventional example, and 10 is a diaphragm arranged on the light incident side of the light receiving lens 6 to control the amount of incident light, and 11 is the light exit side of the light receiving lens 6. For example, a one-dimensional
A position sensor as a position detection element such as a CCD, 12 a signal processor that calculates a change in the object W1 from the reference plane S based on the output signal from the position sensor 11, and 13 a calculation result of the signal processor 12. This is a display device that displays.

Next, the operation of this embodiment will be explained. First, a case where the object W1 is being processed will be described.
During processing, the processing laser beam 1 is focused by the processing lens 2 and irradiates the processing point on the surface of the object W1 to process the object W1. At this time, a part of the processing laser light 1 is diffusely reflected at the processing point and its vicinity, and the object W1 is heated by the energy of the remaining processing laser light 1 to generate light. The light-receiving lens 6 receives such light from the processing point and its vicinity through the aperture 10, and
A light spot image is formed on the position sensor 11. The signal processor 12 removes noise components caused by background light, improves the S/N ratio, and adjusts the displacement of the object W1 from the reference plane S based on the position signal of the light spot image formed on the position sensor 11. A corresponding distance signal is calculated and output. The distance control device 9 controls the position of the processing head 3 in response to this distance signal so that the surface of the object W1 is within a predetermined distance range from the reference surface S, for example, zero from the reference surface S.

For example, if the position sensor 11 is a one-dimensional CCD,
The optical spot image of the position sensor 11 is obtained as a one-dimensional position signal, and signal processing involves calculating the displacement ΔH of the object W1 by detecting the time deviation of the pulse included in this position signal from the reference time. This is made possible by the processing of the device 12. For example, when the surface of the object W1 is on the reference plane S, the position of the light spot image on the position sensor 11 is set to _P1 , and when the surface of the object W1 is also displaced by ΔH from the reference plane S, the position of the light spot image on the position sensor 11 is P1. Let be P ₂ . Here, if the time when point _P1 of the position sensor 11 is scanned is taken as the reference time, the time from this reference time until the point _P2 is scanned corresponds to the distance ΔX between point _P1 and point _P2 . ing. Therefore, the displacement ΔH can be calculated by measuring the regular scanning time from the reference time until the pulse is detected.

Next, the teaching process will be described. During teaching, the processing laser beam 1 is replaced with a visible teaching laser beam, and distance measurement, etc. is performed during teaching by the same operation as above, and the displacement of the surface of the object W1 from the reference plane S is measured. is displayed as a distance by the display device 13 into which the distance signal is input from the signal processor 12.

In addition, in the above embodiment, a one-dimensional position sensor is used.
Although a CCD is used, other linear image sensors or two-dimensional image sensors may be used, and photodiode arrays, PSDs, etc. may be used.
Even if a well-known distance measuring device or the like using a signal processor suitable for the position sensor used is used, the same effect as in the above embodiment can be obtained.

In addition, instead of an aperture, a filter that selects the wavelength range of light can be used on the optical path from the object surface to the position sensor, or a combination of this filter and an aperture can be used to select the measurement light from the object. Needless to say, it is possible to use a diaphragm instead of an diaphragm, an ND filter may be used instead of an diaphragm, a light-receiving lens may also serve as a filter, and in the above embodiments, an diaphragm is sometimes not necessary. Tomoyoshi.

〔Effect of the invention〕

As described above, according to the present invention, during processing, light generated around the processing point is selectively used as a distance measurement light source by heating the processing laser light and the processing laser light without using a distance measurement light source. Since it is configured so that it can be used for distance measurement, it does not change even when the distance between the processing point and the distance measurement position changes, and distance measurement errors do not occur even on curved surfaces, and distance measurement can be performed with high accuracy.
Further, since it is not necessary to provide a separate light source for distance measurement, there is an effect that the configuration can be simplified.

[Brief explanation of drawings]

FIG. 1 is a sectional side view showing a distance measuring device for a laser processing device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional distance measuring device for a laser processing device. In the figure, 1 is a processing laser beam, 2 is a processing lens, 3 is a processing head, 6 is a light receiving lens, and 10 is a processing head.
is an aperture, 11 is a position sensor, 12 is a signal processor,
13 is a display device. In addition, in the figure, the same reference numerals are the same,
or a corresponding portion.

Claims (1)

[Claims of Claims] 1. During processing in which a target object is irradiated with a processing laser beam, the measurement laser beam is irradiated onto the object and the position of the measurement light from the object is detected using a light-receiving lens for focusing. In a distance measuring device for a laser processing device that focuses light on an element and outputs a displacement of the object from a reference plane based on a position detection signal from the position detection element,
A distance measuring device for a laser processing device, characterized in that the processing laser light also serves as the measurement laser light. 2. The distance measuring device for a laser processing device according to claim 1, further comprising a filter for limiting the wavelength range of transmitted light on the optical path from the object to the position detection element. 3. A distance measuring device for a laser processing device according to claim 1 or 2, characterized in that a diaphragm is provided on the light incident side of the light receiving lens. 4. A distance measuring device for a laser processing device according to claim 1 or 2, characterized in that an ND filter is provided on the optical path from the object to the position detection element. 5. Claims 1 to 4, characterized in that during teaching during non-processing, a visible teaching laser emitted instead of the processing laser light is also used as the measurement laser light. A distance measuring device for a laser processing device according to any one of the above. 6. The distance measuring device for a laser processing device according to claim 5, further comprising a display device that displays the detected displacement.