JPH0792191B2 - Machine tool safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is attached to a machine tool such as a press machine, and when an abnormal object enters the monitored area and blocks a light beam, the machine tool is stopped. The present invention relates to a light beam type safety device for generating a signal.

<Prior Art> Conventional light beam safety devices installed in machine tools have a plurality of light emitters and light receivers facing each other in a dangerous area on the front surface of the machine tool, that is, a monitored area. When at least one optical axis is shielded from the plurality of illuminated optical axes, the machine tool is stopped as if a part of the operator's body has entered the monitored range. Has been done.

<Problems to be Solved by the Invention> In such a conventional light beam safety device, the light emitters and the light receivers are arranged side by side at a predetermined interval by the number of optical axes. When setting the optical axis, it is necessary to use a large number of light emitters and light receivers side by side.

In addition, since a light emitting diode that emits normal light is generally used for the light projector, when the width of the monitored range is wide and the optical axis distance is long, the optical axis diameter is widely diffused and the optical axis interval, that is, the light emitting / receiving element. There was a problem that the installation interval of could not be set finely.

In addition, in the field where a machine tool is used, when performing processing using a press machine or a bender, etc., it is necessary to perform processing with part of the processing material or jig protruding from the monitored range of the safety device. There is. In this way, when the processing material 40 protrudes from the monitored area, as shown in FIG.
When the optical axis projected from 41 is shielded by the processing material 40 and does not enter the light receiving section 42, the safety device is activated and the press machine etc. cannot be used, so if such processing is inevitable, The optical axis shielded by the processing material was used as an invalid state. Therefore, the processing material
There is a problem that the area 43 from 40 to the light receiving portion 42 becomes a blind spot of the safety device having no optical axis.

<Means for Solving Problems> The present invention has been made to solve the above problems, and does not require a large number of light emitters and light receivers to be installed side by side as in the prior art, and has a thin optical axis. A large number of optical axes can be generated at narrow intervals, and even when processing is performed by projecting the processing material etc. from the monitored area, the area that becomes a blind spot is not created and safety can be ensured Machine tool safety A device is provided and is configured as follows.

That is, as shown in the overall configuration diagram of FIG. 1, the safety device for a machine tool according to the present invention has two parabolic mirrors 3a and 3b arranged on opposite sides of the monitored area so as to face each other at positions where the optical axes are shifted. In addition, the two reflectors 12a and 12b are arranged on both sides of the parabolic mirrors 3a and 3b so as to face the parabolic mirrors 3a and 3b. Each rotating mirror 2a, 2b is adapted to generate a plurality of parallel optical axes between a pair of parabolic mirrors 3a, 3b and reflectors 12a, 12b.
Two laser oscillators 1a, 1b for irradiating the laser beam are arranged, and two laser beams are reflected by the reflectors 12a, 12b and returned on each optical axis through the half mirrors 4a, 4b. The detector 10 including the light receivers 5a and 5b of
And a control unit 20 which receives the light reception data sent from the detection unit 10 and outputs a stop signal for stopping the machine tool when the optical axis is shielded.

Then, the detection unit 10 drives the two laser oscillators 1a and 1b to project the laser light, and the two rotating mirrors 2
A light-projection scanning processing unit 6 for scanning the optical axis by rotationally driving a and 2b at predetermined angles by a motor, and a light-receiving processing unit 7 for outputting a light-receiving data signal based on the light-receiving signals sent from the light receivers 5a and 5b. The control unit 20 is provided with an optical axis determination means 8 for determining whether or not the all-optical bearing light is based on the received light data signal sent from the detection unit 10, and outputs a stop signal when it is not the all-optical bearing light. Stop command means 9 for issuing a stop command for the machine tool is provided.

<Operation> Therefore, when the rotating mirrors 2a, 2b are synchronously rotated by a predetermined angle while projecting laser light from the laser oscillators 1a, 1b on both sides, the laser light is reflected by the respective rotating mirrors 2a, 2b. The parabolic mirrors 3a and 3b are irradiated while gradually changing the incident angle, and the laser beams from the parabolic mirrors 3a and 3b correspond in parallel to each other at fixed intervals according to the rotation angles of the rotating mirrors 2a and 2b. Light is projected toward the parabolic mirror, and a large number of optical axes are scanned by laser light scanning.
It is formed between a pair of parabolic mirrors 3a, 3b and reflectors 12a, 12b.

At this time, the laser light of each optical axis is reflected by the reflector 12a or 12b, and again the parabolic mirror 3a or 3b and the rotating mirror.
The light passes through 2a and 2b and is received by the light receiver 5a or 5b on the opposite side via the half mirrors 4a and 4b. The light reception signals output from the light receivers 5a and 5b are taken in by the light reception processing means 7, light reception data is created for each scan, the light reception data signal is sent to the control portion 20, and the optical axis determination means 8 outputs all light. It is determined whether the light is a bearing light or not, and if any of the optical axes is blocked and the light is not all-optical bearing light, the stop command means 9 outputs a stop signal to the machine tool.

<Example> Hereinafter, an example of the present invention is described based on a drawing.

The optical system of the detection part of the safety device is configured as shown in FIGS. 2 and 3, and two parabolic mirrors 3a and 3b are provided in front of the dangerous spot of the machine tool, that is, in the monitored area or on both sides. The reflecting optical axes are arranged so as to face each other so as to be slightly offset in the front-rear direction. Then, two reflectors 12a, 12b are arranged on both sides so as to face the respective parabolic mirrors 3a, 3b. The parabolic mirrors 3a and 3b are formed by forming a part of the spherical surface in a vertically elongated arcuate shape.The light projected from the approximate focus position toward the partial spherical surface is always reflected in parallel toward the opposing reflectors 12a and 12b. The reflectors 12a and 12b are structures that always reflect the incident light on the same optical axis as the incident light. Rotating mirrors 2a and 2b (for example, polygon mirrors) are arranged near the focal points of the parabolic mirrors 3a and 3b, respectively. The rotating mirrors 2a and 2b have four reflecting surfaces around them, and the rotating mirror motors 11a and 11b ( For example, a stepping motor) drives the motor to rotate accurately at a constant angle. 1a and 1b are laser oscillators using a HeNe gas laser, a semiconductor laser, etc., which irradiate laser light toward part of the rotating mirrors 2a, 2b, respectively, and the laser light reflected from the rotating mirrors 2a, 2b is parabolic mirror 3a. , 3b are arranged at positions where they are projected onto the inner surface. Between the laser oscillators 1a and 1b and the rotating mirrors 2a and 2b, a condenser lens and half mirrors 4a and 4b inclined by about 45 degrees with respect to the optical axis are arranged. Below the half mirrors 4a, 4b, light receivers 5a, 5b (for example, photodiodes, phototransistors, etc.) via a lens are configured to receive the laser light emitted from the laser oscillator on the opposite side via the half mirrors 4a, 4b. Is installed in.

As shown in the block diagram of FIG. 4, the safety device scans the laser light by rotating the rotating mirrors 2a and 2b, and returns on the optical axis generated between the two parabolic mirrors 3a and 3b and the reflectors 12a and 12b. Which has two light receivers 5a and 5b which respectively receive the laser light to be transmitted via the half mirrors 4a and 4b, and which generates the light reception data, and the light reception data is input from the detection unit 10 and generated by scanning. It is composed of a control unit 20 which outputs a stop signal for stopping the machine tool when there is a light shield on any of a large number of optical axes.

In the detection unit 10, a microcomputer using a so-called one-chip CPU is used as the light emitting scanning processing means and the light receiving processing means, and the CPU 15 for executing the light emitting and receiving processing based on a predetermined program, and fixed information such as program data. It has a ROM 16 for storing, a RAM 17 for reading and writing data such as the number of set optical axes so as to be writable, and an input / output circuit 18, and each unit is connected to each other by a common bus 19 to transmit data and control signals. I / O circuit
18, a driver circuit for rotationally driving the rotary mirror motors 11a, 11b in synchronization, an amplifier for amplifying a received light signal input from the optical receivers 5a, 5b, and then filtering it to a digital signal, A filter and A / D converter are provided.

The laser oscillator 1a, 1b has a built-in drive circuit and modulator,
Laser light modulated at a specific frequency is emitted. The laser oscillators 1a and 1b are controlled to start and stop by the microcomputer, but continuously operate while the safety device is operating. When a stepping motor is used as the motor, the driver that drives the rotating mirror motors 11a and 11b is
Each time each optical axis is generated, a specific number of pulses are output to drive two motors at a constant angle. The optical axis number setting device 13
The number of optical axes to be generated by scanning is set in advance, and is composed of, for example, a digital switch or a numeric keypad.For example, when the height of the monitored area is 1 m, the number of optical axes is 1 cm, and the number of optical axes is 100. Set in a book.

The control unit 20 has a micro computer that forms the above-mentioned optical axis determination unit and stop command unit that receives a light reception data signal from the detection unit 10 and determines whether or not all optical bearing light is present and outputs a stop signal when light blocking occurs. , A check switch 21 operated to check the welding of the main relay contacts, a welding detection circuit 22 as shown in FIG. 5 for detecting the presence / absence of welding of the main relay contacts, and an abnormality detection circuit 23 for detecting an abnormality of the microcomputer. Is equipped with. The microcomputer of the control unit 20 is similar to that of the detection unit 10 described above, and the one-chip CP
CPU 24 configured by using U to execute optical axis determination and stop signal output processing based on a predetermined program, ROM 25 that stores fixed information such as program data, and detector 1
The input / output circuit 27 includes a RAM 26 for reading and writing the received light data and the like sent from 0 in a writable manner. The input / output circuit 27 is connected to the input / output circuit 18 of the detection unit 10 to transmit a synchronizing signal and fetch light reception data. Further, the input / output circuit 27 has a check switch 21, a welding detection circuit 22, and an abnormality detection circuit 23. The auxiliary stop circuit 30 and the stop circuit 31 are connected.

The stop circuit 31 includes a driver and a main relay, and has a structure in which the main relay is operated by the stop signal output from the input / output circuit 27 to stop the machine tool. The auxiliary stop circuit 30 includes a driver and an auxiliary relay, and is configured to operate the auxiliary relay and stop the machine tool when the main relay of the stop circuit 31 causes a malfunction such as welding. As shown in the connection diagram of Fig. 5, the contacts 1xa and 1xb of the main relay 1x and the contact 2xa of the auxiliary relay 2x are connected in parallel between the stop input terminals of the machine tool, and the contact 1xb is connected when the main relay is deenergized. When the auxiliary relay is energized, it is stopped, and the contact 2xa is turned on when the auxiliary relay is energized.

The welding detection circuit 22 for detecting the welding state of the main relay is
As shown in the figure, a photocoupler PC is connected to one contact 1xa of the main relay, and a detection signal is output from the output side of the photocoupler PC via a resistor R. That is, when the stop signal is output and the main relay is in the deenergized state, the contact 1xa is off, so no current flows on the output side of the photocoupler PC,
When the high-level detection signal is output, the stop signal is not output, and the main relay is energized, the contact 1xa turns on.
The output side of the photocoupler PC becomes conductive and a low level detection signal is output.

The detection unit 10 configured as described above is installed near the monitored portion of the machine tool, and the control unit 20 is installed near the control panel of the machine tool, but the detection unit 10 and the detection unit 20 each have a built-in microcomputer. However, since the data is serially transmitted, the line between them may be two for signal and data.

Next, the operation of the detector 10 of the safety device will be described based on the flow chart shown in FIG.

The CPU 15 of the detection unit 10 first performs initialization such as resetting various registers in step 10, and then executes step 11
At 0, the set number of optical axes set by the optical axis number setter 13 is read and stored in the RAM 26. Next, in step 120, the laser oscillators 1a and 1b are activated, and laser light is emitted from the laser oscillators 1a and 1b. Laser light is 5MHz at the modulator
The laser light that has been modulated at a frequency of a certain degree is oscillated continuously.

Then, in step 130, when a synchronizing signal is input from the control unit 20, in step 140, the rotary mirror motors 11a and 11b.
Then, a specific number of drive pulses are output to rotate the rotating mirrors 2a and 2b at a constant angle. At this time, the laser light oscillated from the laser oscillator 1a, 1b is transmitted through the half mirrors 4a, 4b and reflected by the rotating mirrors 2a, 2b, hitting the inner peripheral surfaces of the parabolic mirrors 3a, 3b, and reflected here. As shown in FIG. 2, the laser light travels horizontally in the monitored area and strikes the reflectors 12a, 12b arranged opposite to each other. Then, the laser light reflected by the reflectors 12a, 12b returns on the same optical axis, and the parabolic mirrors 3a, 3b, the rotating mirrors 2a, 2b, the half mirrors 4a, 4 respectively.
After passing through b, the light is received by the light receivers 5a and 5b.

When the light receivers 5a and 5b receive the laser light, a light reception signal is output, the light reception signal is amplified, then passed through a filter circuit to remove the influence of ambient light, and at step 150, the A / D converter. The received light signal that has been passed through and converted into a digital signal is the CPU1
Read in 5. Then, in step 160, it is determined whether or not the light is received based on the light receiving signal. When it is determined that the light receiving signal level is equal to or higher than a predetermined value, the process proceeds to step 170, and the light receiving pulse signal (light receiving data) is controlled. Output to section 20. On the other hand, in step 160, when it is determined that one of the light receivers 5a and 5b is also light-shielded, step 170 is not executed and step 180 is skipped, and "1" is subtracted from the set number of optical axes, Next, it is determined whether or not the number of optical axes subtracted in step 190 is zero.

When the subtraction optical axis number is not 0, the process returns to step 140, the drive pulse is output again to the rotary mirror motors 11a and 11b, and the rotary mirrors 2a and 2b are further rotated by a constant angle. As a result, the laser light reflected by the rotating mirrors 2a, 2b is reflected one step below the parabolic mirrors 3a, 3b, and the next optical axis is formed immediately below the previously generated optical axis. Then, the laser light returned on the optical axis is received by the light receivers 5a and 5b on the same side as above, and the light reception signals output from the light receivers 5a and 5b are converted into digital values in step 150. After being read by the CPU 15, the CPU 15 determines whether or not light is received, and if the two light receivers 5a and 5b are in a light receiving state, a light receiving pulse signal is sent to the control unit 20 and the number of optical axes is further subtracted by "1". In this way, Step 140 to Step 1
By repeating 90, when the subtraction optical axis number becomes 0, one scanning with the laser beam is completed. Then, the process returns from step 190 to step 130, and after inputting the synchronizing signal sent from the control unit 20, steps 140 to 190 are repeated, and the scanning with the laser beam is repeated in the same manner as above.

Next, the operation of the control unit 20 will be described based on the flow chart of FIG.

The CPU 24 of the control unit 20 first outputs the synchronization signal to the detection unit 10 in Step 200, and then reads the light reception pulse signal (light reception data) sent from the detection unit 10 in Step 210. Then, at step 220, the contact 1xa of the main relay for stop,
Determine whether the check switch 21 for checking 1xb welding has been turned on.If the check switch 21 is not turned on, proceed to step 230 and scan the laser light based on the received light data sent from the detection unit 10. It is determined whether or not all the optical axes generated by are in the light receiving state, and if there is no shielded optical axis and the all optical bearing is in the optical state, then in step 240, a safety signal is output to the stop circuit 31. . At this time, the main relay 1x of the stop circuit 31 is energized by the safety signal and the contact 1xa
Since the contact is closed and the contact 1xb is opened, the stop output is not output and the machine tool is not stopped.

On the other hand, if it is determined in step 230 that there is a light-blocking optical axis and all the optical axes are not in the light-receiving state, then step 25
Proceeding to 0, the output of the safety signal is stopped, the main relay 1x of the stop circuit 31 is de-energized, the contact 1xb is turned on, the stop processing is performed, and the machine tool is stopped. Then, step 240
From or from step 250 to step 260, stop circuit
Based on the output signal from the welding detection circuit 22, it is determined whether the contacts 1xa, 1xb of the 31 main relay are in a welded state.If there is no contact welding of the main relay, this processing is terminated and the main relay If the contact welding of No. 2 is present, the process proceeds to Step 320, and an abnormal welding signal is output to the auxiliary stop circuit 30. Auxiliary stop circuit
When the welding abnormality signal is input, 30 energizes the auxiliary relay 2x to close its contact 2xa and perform stop control, and the machine tool stops.

On the other hand, when it is determined in step 220 that the check switch is turned on, step 270 and subsequent steps are executed to check the operation of the stop circuit 31. That is, step 27
At 0, the output of the safety signal is stopped to deactivate the main relay of the stop circuit 31, and its contact 1xb is turned on to stop the machine tool. Then, in step 280, a welding abnormality detection signal is output to the auxiliary stop circuit 30, thereby energizing the auxiliary relay of the auxiliary stop circuit 30 to turn on its contact 2xa, and in step 290, the stop circuit 31 is safe. A signal is output, the main relay of the stop circuit 31 is energized, and the contact 1xb is turned off. In this way, after the contact of the main relay is turned on and off, the process proceeds to step 300, where it is determined whether or not the contact of the main relay is in the welding state based on the output signal from the welding detection circuit 22,
If there is contact welding of the main relay, the process proceeds to step 320 to output a welding abnormality signal to the auxiliary stop circuit 30 to stop the machine tool. On the other hand, if there is no contact welding of the main relay, the process proceeds to step 310, the output of the welding abnormality signal is stopped, the stop control of the auxiliary stop circuit 30 is released, and the inspection operation is ended.

Thus, from step 200 to step 260 or step 260
By repeatedly executing 320, the received light data sent from the detection unit 10 is checked, and if there is a shielded optical axis, the safety signal is stopped and the stop circuit 31 performs stop control to stop the machine tool. Be done. At the same time, the stop circuit 31
The welding state of the main relay is also checked, and if welding is detected, a welding abnormality signal is output to the auxiliary stop circuit 30, and the auxiliary stop circuit 30 controls the stop of the machine tool. Further, when the check switch 21 is turned on, the process proceeds from step 220 to step 270, and steps 270 to 310 are executed to forcibly turn on / off the contact of the main relay of the stop circuit 31 and weld the contact. Is checked.

As described above, in the safety device of the present invention, the laser light is projected from both sides of the monitored area, and the laser light reflected on the reflectors facing each other and returned on the same optical axis is received by the light receiver. Because of the structure, when it is necessary to perform work by projecting a jig, a processing material, etc. from the work area of the machine tool, that is, the area where the optical axis is formed, project the work tool as shown in FIG. If the processing material 40 or the like is attached to the portion where the optical axis is shielded from the reflector 39, it is possible to monitor without forming a blind spot. That is, the optical axis shielded by the protruding processing material 40 is the reflector 39 on both sides.
The parabolic mirrors 3a, 3b and the rotating mirror 2 are reflected by hitting
a, 2b, and the half mirrors 4a, 4b, the light is received by the light receivers 5a, 5b, and an optical axis is generated on both sides of the processed material, so that it is possible to monitor the monitored range without creating a blind spot as in the past. it can.

<Effects of the Invention> As described above, according to the safety device for a machine tool of the present invention, since the optical axis is generated by the laser light, it is possible to project a long distance with the optical axis being narrowed down. Even if the width of the range to be monitored is wide and the optical axis length is long, the optical axis diameter is thick and does not diffuse, and the optical axis gap can be set to be small, so that the eyes can be closely monitored. Furthermore, laser light is projected from the laser oscillators on both sides, the laser light reflected by the reflectors facing each other on the opposite side is returned on the same optical axis, and the returned laser light is received by the light receiver. Therefore, even if the processing material or jig is projected from the monitored area and the processing is performed, if the reflectors are attached to both sides of the processing material or jig (light-shielding points), the blind spot where the optical axis disappears is not created. Can be monitored and safety can be secured.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention, FIGS. 2 to 8 show an embodiment thereof, FIG. 2 is a front view of an optical system of a detector, FIG. 3 is a plan view of the same, and FIG. Block diagram of the safety device, FIG. 5 is a connection diagram of the welding detection circuit, FIG. 6 is a flow chart showing the operation of the detection unit, FIG. 7 is a flow chart showing the operation of the control unit, and FIG. 8 is another example of use. And FIG. 9 is an explanatory view of a conventional safety device. 1a, 1b …… Laser oscillator, 2a, 2b …… Rotating mirror, 3a, 3b
... parabolic mirrors, 4a, 4b ... half mirrors, 5a, 5b ...
... light receiver, 6 ... light emission scanning processing means, 7 ... light receiving processing means, 8 ... optical axis determination means, 9 ... stop command means, 10 ...
Detectors, 12a, 12b ...... Reflectors, 20 ... Control section.

Claims (1)

[Claims] 1. Two parabolic mirrors are arranged on both sides of the monitored area so as to face each other at positions where the optical axes are offset, and two reflectors are arranged on both sides so as to face each parabolic mirror. Rotating mirrors are arranged near the focal points of the parabolic mirrors, respectively, and irradiate the respective rotating mirrors with laser light so as to generate a large number of parallel optical axes between the two pairs of parabolic mirrors and reflectors. A detector provided with two laser oscillators and provided with two light receivers for receiving the laser light reflected by the reflector and returned on each optical axis through a half mirror; A safety device comprising: a control unit for inputting received light data sent from a unit, and outputting a stop signal for stopping the machine tool when the optical axis is shielded, wherein the detection unit includes the two units. The laser A projecting scan processing means for driving a shaker to project a laser beam, and at the same time, for rotationally driving the two rotary mirrors by a motor at a predetermined angle to scan an optical axis, and a light receiving unit sent from the photoreceiver. A light reception processing unit that outputs a light reception data signal based on a signal is provided, and the control unit includes an optical axis determination unit that determines whether all optical bearing light is received based on the light reception data signal sent from the detection unit, A safety device for a machine tool, characterized in that stop command means is provided for outputting a stop signal to issue a stop command for the machine tool when it is not an optical bearing light.