JPH0761591B2 - 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> Conventionally, a general light beam type safety device installed on a machine tool has a plurality of light emitters and light receivers facing each other in a dangerous place on the front surface of the machine tool, that is, a monitored area, and each light emitter projects the light. 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 type safety device, since the light emitters and the light receivers are arranged side by side at a predetermined interval by the number of optical axes, when the monitored range is wide, the intervals are narrow. 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 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 receiving / 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 uses a thin optical axis. A large number of optical axes can be generated at a narrow interval, and even when processing is performed by projecting the processing material from the monitored area, 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, in the safety device for a machine tool of the present invention, as shown in the overall configuration diagram of FIG. 1, two parabolic mirrors 3a and 3b are arranged so as to face each other, and the parabolic mirrors 3a and 3b are respectively provided near the focal points thereof. The rotating mirrors 2a and 2b are arranged, and the two laser oscillators 1a and 1b for irradiating the rotating mirrors 2a and 2b with laser light so as to generate a large number of parallel optical axes between the two parabolic mirrors are provided. Half mirror 4 for laser light on the optical axis
It has two light receivers 5a and 5b that receive light via a and 4b, and a detector 10 that creates received light data, and the received light data from the detector 10 is input, and the machine tool is stopped when the optical axis is shielded. And a control unit 20 that outputs a stop signal to cause the stop. Then, the detection unit 10 drives two laser oscillators 1 to project a laser beam, and at the same time, the two rotary mirrors 2 are synchronously driven by a motor to rotate at predetermined angles to scan the optical axis. Light projection processing means 6 and light reception processing means 7 for outputting a light reception data signal based on the light reception signal sent from the light receiver 5.
Is provided, and the control unit 20 outputs 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 the all-optical bearing light is not received. Stop command means 9 for issuing a stop command for the machine tool is provided.

<Operation> Therefore, when the rotating mirrors 2a and 2b are rotated synchronously by a predetermined angle because the laser light is not projected from the respective laser oscillators 1a and 1b, the laser light is reflected by the rotating mirrors 2a and 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 are parallel to the parabola corresponding to the rotation angles of the rotating mirrors 2a and 2b at fixed intervals. A large number of optical axes are projected onto the mirror by scanning with laser light
It is formed between two parabolic mirrors 3a and 3b.

Then, the laser light on the optical axis passes through the parabolic mirror 3a or 3b on the reflection side and the rotating mirrors 2a, 2b, and is received by the light receiver 5a or 5b on the opposite side via the half mirrors 4a, 4b. Receiver 5a, 5
The light-reception signal output from b is taken in by the light-reception processing means 7, light-reception data is created for each scan, and this light-reception data signal is sent to the control section 20. If it is determined that there is light blocking on any of the optical axes and it 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 FIG. 2 and FIG. 3, and two parabolic mirrors 3a and 3b face each other vertically on the front side of the dangerous place of the machine tool, that is, on both sides of the monitored area. Is installed in. The parabolic mirrors 3a and 3b are formed by forming a part of the spherical surface in a vertical thin arc shape, and a structure in which the light projected from the substantially focal position toward the partial spherical surface is always reflected in parallel toward the opposing parabolic mirrors. Is. 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. Laser oscillators 1a and 1b and rotating mirror 2
A condenser lens and half mirrors 4a and 4b inclined about 45 degrees with respect to the optical axis are arranged between a and 2b. 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 transmits the laser light transmitted through the two parabolic mirrors 3a and 3b to the half mirror 4.
A detector 10 having two light receivers 5a and 5b respectively receiving light via a and 4b, and generating a light reception data, and any of a large number of optical axes generated by scanning after receiving the light reception data from the detection unit 10. When there is shading, the control unit 20 outputs a stop signal for stopping the machine tool.

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,
A laser beam 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 for driving the rotating mirror motors 11a and 11b outputs a specific number of pulses each time each optical axis is generated and synchronizes the two motors at a fixed angle at the same time. To drive. The optical axis number setter 13 is for presetting the number of optical axes to be generated by scanning, and is configured by, for example, a digital switch or a numeric keypad, and, for example, when the height of the monitored range is 1 m, the optical axes are generated at 1 cm intervals. If you do, set the number of optical axes to 100.

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 and transmits a synchronization signal and captures received light data. Further, a check switch 21, a welding detection circuit 22, an abnormality detection circuit 23, an auxiliary stop circuit 30, and a stop circuit 31 are connected to the input / output circuit 27.

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 location of the machine tool, and the control unit 20 is installed near the control panel of the machine tool.The detection unit 10 and the control 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 100, 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 emitted at the modulator, for example, 5 MHz
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.
A specific number of drive pulses are output to the rotary mirrors 2a and 2b to rotate them simultaneously at a constant angle. At this time, laser oscillators 1a, 1b
The laser light oscillated from the laser transmits through the half mirrors 4a and 4b, is reflected by the rotating mirrors 2a and 2b, hits the inner peripheral surfaces of the parabolic mirrors 3a and 3b, and the laser light reflected here is shown in FIG. Thus, one optical axis is formed on the same optical path in the opposite directions.

In this way, the laser beams projected from the laser oscillators 1a and 1b on both sides hit the parabolic mirrors 3b and 3a on the opposite sides, respectively, are reflected by the rotating mirrors 2b and 2a, and are received via the half mirrors 4b and 4a. The light is received by the devices 5b and 5a.

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.

Then, when the subtraction optical axis number is not 0, the process returns to step 140, the drive pulse is output again to the rotating mirror motors 11a and 11b, and the rotating mirrors 2a and 2b are further rotated at a constant angle at the same time. 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, similarly to the above, the laser light projected from the reflection side of the optical axis is received by the light receivers 5a and 5b on the opposite side, and the light reception signals output from the light receivers 5a and 5b are at step 150. After being converted into a digital value and read by the CPU 15, the CPU 15 determines whether or not light is received, and then the two light receivers 5a,
If 5b is in the light receiving state, a light receiving pulse signal is sent to the control unit 20 and the number of optical axes is further decremented by "1". In this way, by repeating Step 140 to Step 190, when the subtraction optical axis number becomes 0, one scanning with the laser light is completed. Then return from step 190 to step 130,
After inputting the synchronization signal sent from the control unit 20,
The steps 140 to 190 are repeated, and the scanning with the laser beam is repeated as described 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 contacts 1xa, 1 of the main relay for stopping
It is determined whether or not the check switch 21 for checking the welding of xb is turned on.If the check switch 21 is not turned on, the process proceeds to step 230, and the laser light scanning is performed 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 on. 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, the safety device of the present invention has a structure in which the laser light is projected from both sides of the monitored area and is received by the light receiver on the opposite side through the same optical path, and therefore the jig is moved from the work area of the machine tool. When it is necessary to perform the work by projecting a processing material or the like from the monitored range, that is, the area where the optical axis is formed, as shown in FIG. If you glue it, you can monitor it without creating a blind spot. That is, the optical axis shielded by the protruding processing material 40 is the reflector 39 on both sides.
Is reflected on the same side through the parabolic mirrors 3a and 3b, the rotating mirrors 2a and 2b, and the half mirrors 4a and 4b.
The light is received by 5a and 5b, the optical axis is generated on both sides of the processed material, and the monitored range can be monitored without making a blind spot as in the past.

<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 beam, 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. Further, since laser light is emitted from the laser oscillators on both sides and each laser light is received by the light receiver on the opposite side through the same path, processing is performed by projecting a processing material or jig from the monitored range. Even if
If reflectors are attached to both sides of the processing material or jig (light-shielding points), it is possible to monitor without making a blind spot where the optical axis disappears and ensure safety.

[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 mirror, 4a, 4b ... half mirror, 5a, 5b ... photoreceiver, 6 ... projection scanning processing means, 7 ...... Light receiving processing means, 8 ...... Optical axis determination means, 9 ...... Stop instruction means, 10 ...... Detection section, 20 ...... Control section.

Claims (1)

[Claims] 1. Two parabolic mirrors are arranged so as to face each other, and rotating mirrors are respectively disposed near the focal points of the respective parabolic mirrors so that a large number of parallel optical axes are generated between the two parabolic mirrors. A detection unit having two laser oscillators for irradiating the respective rotating mirrors with the laser light and two light receivers for receiving the laser light on the optical axis through the half mirrors, and a detection unit for generating received light data, A safety device comprising: a control unit for inputting received light data from the detection unit and outputting a stop signal for stopping the machine tool when the optical axis is shielded; The laser oscillator of the table is driven to project the laser beam, and at the same time, the two rotary mirrors are synchronously rotated and driven by a motor at a predetermined angle to scan the optical axis, and the light receiving scanning processing means, and the light receiving unit. Receiving from the vessel 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, which is provided with stop command means for outputting a stop signal to issue a stop command for the machine tool when the light is not optical bearing light.