JPH0829423B2 - Automatic teaching device for laser processing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a device for performing automatic teaching using a laser beam for teaching, and more particularly to measuring not only the displacement of a workpiece as a distance but also the workpiece. The present invention relates to an automatic teaching device for a laser processing machine capable of detecting a surface condition such as a tape attached to the surface of a workpiece.

[Conventional technology]

Japanese Patent Application No. 59-227,226 discloses a distance measuring device in which a teaching laser is attached to the processing head of a laser processing machine, and a distance measuring device in which the teaching laser light is also used as the processing laser light. Further, it has been conventionally practiced to replace the processing head and the teaching head as needed.

FIG. 2 is a general configuration diagram showing a conventional non-contact type distance measuring device disclosed in, for example, Japanese Patent Publication No. 58-42411. In the figure, (1) is a measurement head, and this measurement head (1) collects a light source (2) and a light beam emitted from this light source (2) to emit light onto an object to be measured (3). The light projecting lens (5) for forming an image as the spot (4), the light receiving lens (6) for condensing the light spot (4), and the light receiving lens (6) are disposed on the image forming surface of the light spot (4). )
Of a photodetector such as a semiconductor position detecting element (hereinafter referred to as PSD) that sends out an electric signal corresponding to the image forming position of
Abbreviated) (7) is included. (8a) and (8b) are current signals I
_A current / voltage conversion circuit for converting a and Ib into voltage signals V _A and V _B , respectively, and (9) adds the voltage signals V _A and V _B to obtain a sum signal V _A +
An adder circuit that sends V _B , (10) an error detection circuit that detects an error between the sum signal V _A + V _B and a predetermined reference value, and sends a difference signal between them, and (11) a light source based on the difference signal A light source drive circuit for variably lighting the output of (2), and (12) based on the voltage signals V _A and V _B sent from the current / voltage conversion circuits (8a) and (8b), respectively, as will be described later. DUT (3)
Is a distance calculation circuit that calculates the displacement of as a distance and sends the distance output.

The conventional distance measuring device is configured as described above, and the light source (2) driven by the light source driving circuit (11).
The light beam emitted from the light source is collected by the light projecting lens (5) and projected as a light spot (4) on the DUT (3). The light spot (4) is further condensed by the light receiving lens (6) and projected and imaged on the PSD (7). Current signal I sent from each end of this PSD (7)
a and Ib change according to the position of the light-receiving image of the optical spot (4) on the PSD (7). That is, the received image is PSD
When in the center of (7), Ia = Ib, but the received light image
When Ia is touched, Ia increases and Ib decreases, and conversely, when the received image shifts to Ib, Ib increases and Ia decreases. Therefore, the displacement of the object to be measured (3), that is, the change of the position of the optical spot (4), is defined as the distance from the center position of the PSD (7) to the position of the light-receiving image on the PSD (7) as shown in (1) below. ) Can be calculated as P multiplied by a certain conversion coefficient.

Also, according to the following equation (2) or equation (3), PS
Since the distance from each end of D (7) to the received light image is obtained, these can be converted into the distance to the object to be measured (3) by the same principle of triangulation.

At this time, if the denominator (Ia + Ib) of the equations (1) to (3) is kept constant, P, P _A and P _B are approximated by P ′ = Ia−Ib (1 ′) P _A ′ = since the _{Ia (2 ') P B'} = Ib (3 '), it may be converted to distance them based.

On the other hand, when sufficient accuracy is required, equation (1) ~
The distance is calculated using one of the equations (3), and in this case also, the light source is set so that the denominator (Ia + Ib), which changes according to the state of the DUT (3), does not affect the distance measurement accuracy. The light amount of (2) is controlled so that the denominator (Ia + Ib) becomes almost constant.

[Problems to be solved by the invention]

In the conventional distance measuring device, the change of the surface state of the object to be measured, which is obtained as the amount of light returned from the optical spot (4) on the object to be measured (3), is simply canceled by the light source drive circuit (11).
Information other than distance information could not be easily obtained without any aggressive signal processing. Therefore, when the distance measuring device is attached to various devices and used, the surface condition cannot be discriminated because the extraction of the surface condition feature of the object (3) depends only on the distance information. In addition, there is a problem that it is necessary to perform a complicated calculation using the distance measurement value even when the determination can be made.

The present invention has been made to solve such a problem, and an object of the present invention is to obtain an automatic teaching device for a laser processing machine that can easily detect the surface state of a work piece while measuring the distance of the work piece. To aim.

[Means for solving problems]

An automatic teaching device for a laser processing machine according to the present invention includes a processing laser which irradiates a workpiece with a processing laser beam from a head provided in the main body of the processing machine to process the workpiece. A teaching laser for irradiating the workpiece with a working laser beam from the head, a means for switching between the working laser beam and the teaching laser beam, and receiving the laser beam from the workpiece and adjusting the received light amount. A light receiving system that generates a corresponding current signal, a variable gain amplifier that converts the current signal from the light receiving system into a voltage signal, and an output measuring device that measures the output of the teaching laser and converts it into another electric signal. And a distance signal representative of the distance from the head to the workpiece based on the voltage signal from the variable gain amplifier, and the gain signal of the variable gain amplifier is controlled so that the voltage signal has a predetermined value. And a signal processing circuit for generating a surface state signal representing the surface state of the workpiece by dividing the control signal by the electric signal from the output measuring device. is there.

[Action]

In the present invention, the light receiving system generates a current signal corresponding to the amount of received laser light from the workpiece, the variable gain amplifier converts the above current signal into a voltage signal, and the output measuring device outputs the teaching laser light. The output is converted to an electric signal, and the signal processing circuit generates a distance signal based on the voltage signal described above to generate a control signal for controlling the gain of the variable gain amplifier and divide the control signal by the electric signal described above. And generate a surface condition signal.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention,
(21) is a processing laser that emits the processing laser light (21A), such as a CO ₂ laser, (22) is a teaching laser that emits the teaching laser light (22A), such as a He-Ne laser, and (23) is the processing Means for switching between the teaching laser light (21A) and the teaching laser light (22A), which is placed in the optical path of the teaching laser (22) and transmits a part of the teaching laser light (22A) but leaves the rest. Reflective half mirror (23A), this half mirror (23A
A mechanical laser (23B) for tuning the teaching laser light (22A) that has passed through A) and a laser light switching shutter (23C) are included. The laser light switched by the shutter (23C) is transmitted to the work (3A) by the projection lens (5) in the only head (24A) provided in the main body (24) of the laser processing machine. Is irradiated. (25) is a tape attached to the surface of the work (3A). (26) is a light receiving system, which is the light receiving lens (6) described above with reference to FIG.
And a photodetector, eg PSD (7). The current / voltage conversion circuits (8a) and (8b) described above with reference to FIG. 2 are connected to the output side of the light receiving system (26), specifically, the SPD (7), and current signals from the respective ends of the PSD (7). Preamplifiers (27A) and (27B) for amplifying Ia and Ib, and an electric current corresponding to the amount of received laser beam (21A) or (22A) from the work piece (3A) as a voltage signal Signal V _A ,
Variable gain amplifier is converted to V _B (28A), consisting of (28B). Reference numeral (29) is an output measuring device for measuring the output of the teaching laser (22) from the teaching laser light (22A) reflected by the half mirror (23A) and converting it into an electric signal Q.
(30) is a signal processing means electrically connected to the switching means (23), the light receiving system (26) and the output measuring device (29),
_A multiplexer (30A) that switches between voltage signals V _A and V _B , a sample hold circuit (30B) that samples and holds the output of this multiplexer (30A), and an A / D converter (analog / digital converter that converts the sampled and held output). 30C), the head (24A) based on the output of this A / D converter (30C) and the electric signal Q from the output measuring device (29).
A control signal that generates a distance signal that represents the distance from the workpiece to the workpiece (3A) and controls the gains of the variable gain amplifiers (28A) and (28B) so that the voltage signals V _A and V _B have predetermined values. A signal processing circuit (30D) that generates V _G and a surface condition signal that represents the surface condition of the workpiece (3A), and the above-mentioned circuits (30A) in synchronization with the mechanical tipper (23B).
Includes a timing circuit (30E) for supplying timing pulses to (30D).

In the automatic teaching device for a laser processing machine configured as described above, the operation when the workpiece (3A) is being processed will be described first. In this case, the processing laser light (21A) from the processing laser (21) is switched by the switching means (23).
Is selected. Laser light for processing (21A) that passed through the shutter (23C), processing machine body (24) and its head (24A)
Is squeezed by the projection lens (5) and the workpiece (3
A) Irradiate a predetermined processing point on the surface of (A) to be processed (3A)
To process. At this time, a part of the processing laser light (21A) is diffusely reflected at the processing point and the vicinity thereof, and the work (3A) is heated by the energy of the remaining processing laser light (21A) to emit light. Emit. These lights are projected and imaged on the PSD (7) by the light receiving lens (6) in the light receiving system (26). The current signals Ia and Ib from the respective ends of the SPD (7) are respectively converted into current / voltage conversion circuits (8a) and (8
Variable gain amplifiers (28A), (28B) whose gain is controlled by the control signal V _G from the signal processing circuit (30D) after being amplified by the preamplifiers (27A), (27B) in (b). ), It is converted into voltage signals V _A and V _B. This voltage signal V _A , V _B
Are alternately taken into the multiplexer (30A) under the control of the timing circuit (30E) in the signal processing means (30), sample-held by the sample-hold circuit (30B), and digitally by the A / D converter (30C). After being converted into a signal, the signal processing circuit (30D) performs arithmetic processing to form a distance signal.

Next, the operation during teaching will be described. In this case, it is emitted from the teaching laser (22), transmitted through the half mirror (23A) in the switching means (23) and the mechanical tip (23B).
The teaching laser beam (22A) that has been adjusted by the laser is selected by the shutter (23C). A part of the teaching laser light (22A) is reflected by the half mirror (23A), then converted into another electric signal Q by the output measuring device (29) and supplied to the signal processing circuit (30D). It The teaching laser light (22A) selected by the shutter (23C) also passes through the processing machine body (24) and its only head (24A), and the projection lens (5)
After being squeezed by, it is projected onto the workpiece (3A). When the head (24A) is moved in the direction shown by the arrow while maintaining the relative positional relationship between the head (24A) and the work piece (3A), the surface state of the work piece (3A), for example, the work piece (3A) The tape (25) attached to the surface of (3A) can be detected. More specifically, the teaching laser light (22A) reflected on the tape (25) and the vicinity thereof is received by the light receiving system (26) and converted into current signals Ia, Ib as in the case of processing. , Current / voltage conversion circuit (8a), (8
In b), it is converted into voltage signals V _A and V _B , and signal processing means (30)
Inside multiplexer (30A), sample and hold circuit (3
0B) and the A / D converter (30C) perform signal processing, and then supply the signal processing circuit (30D). This signal processing circuit (30D) uses current signals I _A and I _B from the light receiving system (26) and voltage signals from the variable gain amplifiers (28A) and (28B).
V _A, the distance signal of the above-generated based on V _B, the electric signal Q and the control signal V _G with generating a control signal V _G described above
A surface condition signal is generated by dividing by, that is, the tape (25) is detected. The surface condition signal is Q
But but corresponds to the V _G if certain, if Q is not constant V _G
Corresponds to / Q.

〔The invention's effect〕

As described above, according to the present invention, the processing laser light is applied to the workpiece from the only head provided in the main body of the processing machine to process the workpiece, and the teaching laser light is used. A teaching laser for irradiating the workpiece from the head, a means for switching between the processing laser light and the teaching laser light, and receiving a laser from the workpiece to generate a current signal corresponding to the received light amount. A light receiving system, a variable gain amplifier for converting the current signal from the light receiving system into a voltage signal, an output measuring device for measuring the output of the teaching laser and converting it into an electric signal, and the variable gain amplifier A distance signal representing a distance from the head to the workpiece is generated based on the voltage signal, and a control signal for controlling the gain of the variable gain amplifier is generated so that the voltage signal has a predetermined value. Since the control signal is divided by the electric signal from the output measuring device to generate a surface condition signal representing the surface condition of the workpiece, the displacement or distance of the workpiece can be calculated. It is possible to easily obtain an automatic teaching device for a laser processing machine that can not only perform measurement but also detect the surface state of a workpiece.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional distance measuring device. In the figure, (21) is a processing laser, (21A) is a processing laser beam, (22) is a teaching laser, (22A) is a teaching laser beam, (23) is a switching means, (23C) is a shutter, (2
4) is the machine body, (24A) is the head, (3A) is the work piece, (25) is the tape, (26) is the light receiving system, (28A) and (28A).
B) is a variable gain amplifier, (29) is an output measuring device, (30) is a signal processing means, and (30D) is a signal processing circuit. In each drawing, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A processing laser for irradiating a workpiece with a processing laser beam from a single head provided in a main body of a processing machine to process the workpiece, and a teaching laser beam from the head to the workpiece. A teaching laser for irradiating a work, a means for switching between the working laser light and the teaching laser light, and a light receiving system for receiving the laser light from the work and generating a current signal corresponding to the received light amount. A variable gain amplifier for converting the current signal from the light receiving system into a voltage signal, an output measuring device for measuring the output of the teaching laser and converting it into an electric signal, and the voltage signal from the variable gain amplifier. A distance signal representing the distance from the head to the workpiece, and a control signal for controlling the gain of the variable gain amplifier so that the voltage signal has a predetermined value. Laser processing machine for automatic Teichingu apparatus characterized by comprising a signal processing circuit for generating a surface state signal representative of the surface condition of the said workpiece by dividing the electrical signal from the output measuring device.