JPS6362999A - Safety device for machine tool - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention is attached to a machine tool such as a press machine, and stops the machine tool when an abnormal object enters the monitored range and blocks the light beam.

[This relates to a light beam type safety device that generates a stop F signal that causes damage. <Conventional technology> Conventionally, general optical beam safety devices installed on machine tools have multiple emitters and receivers installed facing each other in the dangerous area in front of the machine tool, that is, the area to be monitored. It is configured to stop the machine tool when at least one of the multiple optical axes is blocked, assuming that a part of the worker's body has entered the monitored range. has been done. <Problems to be solved by the invention> In such conventional optical beam safety devices, the number of emitters and receivers are arranged side by side at a predetermined interval, equal to the number of optical axes. When trying to set the optical axis, it is necessary to use a large number of emitters and receivers in line. In addition, since light emitting diodes that emit normal light are generally used for floodlights, when the range to be monitored is wide and the optical axis distance is long, the optical axis diameter becomes thick and diffuses, and the optical axis spacing, that is, the light emitting/receiving element. There was a problem in which the installation interval could not be set in detail. Means for Solving the Problems> The present invention was made to solve the above problems, and it eliminates the need to install a large number of emitters and receivers side by side as in the past, and uses a narrow optical axis. The present invention provides a machine tool safety 'A21 that can generate a large number of optical axes at narrow intervals and can reliably ensure the safety of the machine tool, and is constructed as follows. That is, in the machine tool safety device of the present invention, as shown in the overall configuration diagram of FIG. A laser oscillator 1 emits laser light toward the rotating mirror 2 so as to generate a large number of parallel optical axes between the reflector 12 and the parabolic mirror, and a laser oscillator 1 receives laser light along each optical axis via a half mirror 4. a detection unit 10 that has a light receiver 5 and generates light reception data, and a control unit that inputs the light reception data from the detection unit 10 and outputs a stop W signal to stop the machine tool when there is light interruption on the optical axis. It consists of 20. The detection unit 10 includes a light projection scanning processing means 6 that drives the laser oscillator 1 to project a laser beam, and also rotates the rotary mirror 2 by a predetermined angle by a motor to scan the optical axis. A light reception processing means 7 is provided which outputs a light reception data signal based on the light reception signal sent from the light receiver 5, and the control section 20 determines whether or not all optical axis light is received based on the light reception data signal sent from the detection section 10. an optical axis determination means 8; and a stop 1 which outputs a stop signal and issues a stop command to the machine tool when not all optical axes are received;
- Operation of the commanding means 9
The laser beams are irradiated to the rotating mirror 2 in parallel from the parabolic mirror 3 while gradually changing the incident angle.
Light is projected toward the reflector at regular intervals according to the rotation angle of the parabolic mirror 3, and a large number of optical axes are formed between the parabolic mirror 3 and the reflector by laser beam scanning. The laser light on the optical axis reflected by the reflector returns through the parabolic mirror 3 and the rotating mirror 2, and is received by the light receiver 5 via the half mirror 4. The light reception signal output from the light receiver 5 is taken into the light reception processing means 7,
Light reception data is created for each scan, this light reception data signal is sent to the control unit 20, and the optical axis determination means 8 determines whether or not all optical axes have been received, and if any of the optical axes is blocked. If all optical axes are not received, the stop 1 to command means 9 instruct the machine tool to stop I.
- Output a signal. <Example> An example of the present invention will be described below based on the drawings. The optical system of the detection section of the safety device is constructed as shown in Figures 2 and 3, with a parabolic mirror 3 and a reflector 12 facing each other vertically in front of the dangerous area of the machine tool, that is, on both sides of the monitored area. It will be rubbed. The parabolic mirror 3 is a part of a spherical surface formed into a vertically thin arcuate shape, and has a structure that always reflects the light projected toward the partial spherical surface from the approximate focal point in parallel toward the reflector 12. Reference numeral 12 denotes a structure that reflects light incident directly on its surface in the same optical path direction. A rotating mirror 2 (for example, a polygon mirror) is disposed approximately near the focal point of the parabolic mirror 3, and the rotating mirror 2 has four reflective surfaces around it, and is accurately rotated at a constant angle by a rotating mirror motor 11 (for example, a stepping motor). Rotationally driven. 1 is a laser oscillator using a HeNe gas laser, a conductor laser, etc., which irradiates a part of the rotating mirror 2 with a laser beam, and projects the laser beam reflected from the rotating mirror 2 onto the inner surface of the parabolic mirror 3. It is placed in a position where Laser oscillator l and rotating mirror 2 Ill has a condensing lens and a half mirror 4 tilted at approximately 45 degrees with respect to the optical axis
will be placed. A light receiver 5 (for example, a photodiode, a phototransistor, etc.) is disposed below the half mirror 4 through a lens so as to receive the laser light reflected by the reflector 12 and returned through the half mirror 4. As shown in the block diagram of FIG. 4, the safety device includes a light receiver 5 that scans the laser light by rotating a rotating mirror 2 and receives the reflected and returned laser light via a half mirror. a detection unit 10 that generates a signal, and a control unit that inputs received light data from the detection unit 10 and outputs a stop signal to stop the machine tool when there is a light blockage on any of the many optical axes generated by scanning. 20, a microcomputer using a so-called one-chip CPtJ is used as a light emitting scanning processing means and a light receiving processing means, and a CPU 15 that executes light emitting and receiving processing etc. based on a predetermined program; A ROM 16 that stores fixed information such as data, and a RAM 17 that stores data such as the number of set optical axes in a readable and writable manner.
, and an input/output circuit 18, each unit is interconnected by a common path 19 to transmit data and control signals. The input/output circuit 18 includes a driver circuit for rotationally driving the rotary mirror motor 11, an amplifier, a filter, and an A/D for amplifying and filtering the light reception signal input from the light receiver 5 and converting it into a digital signal. A transducer is provided. The laser oscillator 1 includes a drive circuit and a modulator, and emits laser light modulated at a specific frequency. The laser oscillator l is controlled to start and stop by a microcomputer, but it operates continuously when the safety device is activated.
When a stepping motor is used as the motor, the driver for driving the rotating mirror motor 11 outputs a specific number of pulses each time each optical axis is generated to drive the motor by a fixed angle. The number of optical axes setting device 13 is used to preset the number of optical axes generated by scanning, and is composed of, for example, a digital switch or a numeric keypad. If it occurs,
The number of optical axes is set to 100. The control unit 20 includes the above-mentioned optical axis determination means (VP+) and command means, which receives received light data signals from the detection unit 10, determines whether or not all optical axes are received, and outputs a stop F signal when a light blockage occurs. A check switch that has a microcomputer and operates to check for welding of the main relay contacts? 1. Welding detection circuit 22 as shown in FIG. 5, which detects whether or not the main relay contacts are welded. and an abnormality detection circuit 23 for detecting abnormalities in the microcomputer. The microcomputer of the control section 20 is -I:, the above-mentioned detection section l
Similar to that of O, it is configured using a one-chip CPU and performs optical axis judgment and stop 1 based on a predetermined program.
- Consists of a CPU 24 that executes signal output processing, a ROM 25 that stores fixed information such as program data, a RAM 26 that stores light reception data sent from the detection unit 10 in a readable and writable manner, and an input/output circuit 27. 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.
The input/output circuit 27 includes a check switch 21, a welding detection circuit 22, an abnormality detection circuit 23. A circuit 31 is connected to the auxiliary external circuit 3° and the stop. The stop circuit 31 consists of a driver and a main relay, and has a structure in which the main relay is operated in response to a stop signal output from the input/output circuit 27 to stop the machine tool. The auxiliary stop F circuit 3o consists of a driver and an auxiliary relay, and if the main relay of the stop circuit 31 malfunctions such as welding,
The machine tool is configured to operate an auxiliary relay to stop the machine tool. As shown in the connection diagram in Fig. 5, contacts 1xa and IXb of main relay lx and contact 2xa of auxiliary relay 2x are connected in parallel between the stop F input terminals of the machine tool, and when the main relay is de-energized, contact 1xb turns on and enters the stop I-state,
When the auxiliary relay is in the energized state, the contact 2xa is turned on and the auxiliary relay is in the stopped state. The welding detection circuit 22, which detects the welding state of the main relay, is configured by connecting a photocoupler PC to one contact 1xa of the main relay, as shown in FIG. Outputs a detection signal. That is,
When the stop signal is output and the main relay is de-energized, contact 1
Since xa is off, no current flows to the output side of the photocoupler PC, a high-level detection signal is output, and when the stop signal is not output and the main relay is in poor condition, contact IXa turns on. The output side of the photocoupler PC becomes conductive and a low level detection signal is output. The detection section 10 configured as described above is installed near the monitored point of the machine tool, and the control section 20 is installed near the control panel of the machine tool, but the detection section 10 and the control section 20 are each equipped with a microcomputer. Since it is built-in and transmits data serially, the lines between them can be two trees, one for signals and one for data. Next, the operation of the detection section 10 of the safety device will be explained based on the flowchart shown in FIG. The CPU 15 of the detection unit 10 first performs initialization such as resetting various registers in step 100, and then
At step 110, the set number of optical axes set by the number of optical axes setter 13 is read and stored in the RAM 26.Next, at step 120, the laser oscillator 1 is started to oscillate a laser beam from the laser oscillator l. be done. The laser light is modulated by a modulator at a frequency of, for example, about 5 MHz, and the modulated laser light is continuously oscillated. Subsequently, in step 130, a synchronization signal is input from the control unit 20, and in step 140, a specific number of drive pulses are output to the rotating mirror motor 11 to rotate the rotating mirror 2 by a certain angle. At this time, the laser beam oscillated from the laser oscillator 1 passes through the half mirror 4 and rotates through the rotating mirror 2.
The laser beam is reflected by dust on the inner circumferential surface of the parabolic mirror 3, and the laser beam reflected there propagates in the horizontal direction, forming one optical axis, as shown in FIG. Laser beam frefter 1
2, the laser beam is reflected so as to travel along the same optical path as the incident light, and is reflected in the opposite direction on the inner peripheral surface of the parabolic mirror 3. The laser beam is reflected by the rotating mirror 2, and then reflected downward by the half mirror 4. The light is reflected by the light receiver 5 and received by the light receiver 5. When the light receiver 5 receives the returned laser beam, a light reception signal is output, and after being amplified, the light reception signal passes through a filter circuit to eliminate the influence of disturbance light, and in step 150, the light reception signal is outputted to the A/D converter. The received light signal is converted into a digital signal and read into the CPU 15. Then, in step 160, it is determined whether or not light has been received based on the light reception signal, and when the level of the light reception signal is equal to or higher than a predetermined value and it is determined that light has been received, the process proceeds to step 170, where the light reception pulse signal (light reception data) is controlled. Output to mfa2o. On the other hand, if it is determined in step 160 that light is not received but light is blocked, step 170 is not executed and the process directly jumps to step 180, "1" is subtracted from the set number of optical axes, and then step 19
It is determined whether the number of optical axes subtracted by 0 is O. When the number of optical axes to be subtracted is not O, the process returns to step 140, and a drive pulse is again output to the rotating mirror motor t1, 1 to further rotate the rotating mirror 2 by a certain angle. As a result, the laser beam reflected by the one-rotation mirror 2 is reflected one step below the parabolic mirror 3, and the next optical axis is formed immediately below the previously generated optical axis. and,
The return laser beam on the leading axis is received by the light receiver 5 in the same manner as above, and the light reception signal output from the light receiver 5 is converted into a digital value in step 150 and the CPU 15
After the CPU 15 determines whether or not light is received,
If it is in the light receiving state, it sends a light receiving pulse signal to the control unit 20,
Further subtract "1" from the number of optical axes. In this way, steps 140 to 190 are repeated, and when the number of optical axes to be subtracted reaches O, one scan by the laser beam is completed. and steps 190 to 130
After returning to step 1 and inputting the synchronization signal sent from the control section 20, steps 140 to 190 are repeated, and scanning with the laser beam is repeated in the same manner as above. Next, the operation of the control section 20 will be explained based on the flowchart of FIG. First, in step 200, the CPU 24 of the control unit 20
The synchronization signal is output to the detection unit 10, and then in step 210, the light reception pulse signal (light reception data) sent from the detection unit 10 is read, and in step 220, the main stop relay contact lxa, It is determined whether the check switch 21 for checking the welding of the 1xb is turned on, and if the check switch 21 is not turned on, then step 2 is performed.
Proceeding to step 30, based on the light reception data sent from the detection unit 10, it is determined whether all optical axes generated by scanning the laser beam are in the light receiving state, and if there are no optical axes blocked and all optical axes are in the light receiving state. If so, first, in step 240, a safety signal is output to the stop circuit 31. At this time, the main relay IX of the stop circuit 31 is energized by the safety signal, closing contact 1xa and opening contact 1xb, so it stops. H output is not output and the machine tool is not stopped. If it is determined in step 230 that there is an optical axis with a light-shielding state of 1 g and all the optical axes are not in a light-receiving state of 7 g, then the process proceeds to step 250, where the output of the safety signal - is stopped and the system is stopped. A stop process is performed in which the main relay IX of the circuit 31 is deenergized and its contact 1xb is turned on, thereby stopping the machine tool. Next, the process advances from step 240 or from step 250 to step 260, and the contact 1xa of the main relay of the stop circuit 31 is
, lxb is in a welded state based on the output signal from the welding detection circuit 22, and if the main relay contacts are not welded, this process ends; if the main relay contacts are welded, the process ends. First, the process proceeds to step 320, where a welding abnormality signal is output to the auxiliary stop circuit 30. The auxiliary stop circuit 30 energizes the auxiliary relay 2X upon input of the welding abnormality signal, closes its contact 2xa, performs the stop F control, and the machine tool is stopped. On the other hand, if it is determined in step 220 that the check switch is turned on, steps 270 and subsequent steps are executed to check the operation of the stop F circuit 31. That is, in step 270, the output of the safety signal is stopped and the stop circuit is The main relay 31 is deenergized and its contact 1xb is turned on to stop the machine tool +L. Then, at step 280,
A welding abnormality detection signal is output to the auxiliary stop circuit 30, which energizes the auxiliary relay of the auxiliary stop circuit 30 and closes its contact 2.
xa is turned on, and further, in step 290, a safety signal is output to the stop circuit 31, the main relay of the stop circuit 31 is energized, and the contact 1xb is turned off. After turning on and off the contacts of the main relay in this way, the process proceeds to step 300,
It is determined based on the output signal from the welding detection circuit 22 whether or not the contacts of the main relay are in the weld state 7i. If the contacts of the main relay are welded, the process proceeds to step 320 and a welding abnormality signal is sent to the auxiliary stop circuit. output to 30 to stop the machine tool,
On the other hand, if the main relay contacts are not welded, step 3
Proceeding to step 10, 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 completed. In this way, by repeatedly executing steps 200 to 260 or 320, the light reception data sent from the detection unit 10 is checked, and if there is a blocked optical axis, the safety signal is stopped and the stop circuit is activated. 31 performs stop control to stop the machine tool. At the same time, the welding state of the main relay of the stop F circuit 31 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 performs stop control of the machine tool. Furthermore, when the check switch 21 is turned on, steps 220 to 27
By proceeding to step 0 and executing steps 270 to 310, the contacts of the main relay of the stop circuit 31 are forcibly turned on and off, and the welded state of the contacts is checked. <Effects of the Invention> As explained above, according to the safety equipment of the machine tool of the present invention, since an optical axis is generated by a laser beam, it is possible to project light over a long distance with the optical axis narrowly focused. Even if the range to be monitored is wide and the optical axis length is long, the optical axis diameter is thick and does not spread, and the optical axis gap can be set narrow, allowing narrow-eyed monitoring.In addition, rotating mirrors and parabolic Since many parallel optical axes are generated by mirrors, only one laser oscillator needs to be installed, and since the laser beam that returns on the same optical path as the emitted light is received via a half mirror, one laser oscillator is required. It is only necessary to install a light receiver, and the structure can be made relatively compact. Furthermore, the distance between the optical axes can be changed simply by changing the rotation angle for each step of the rotating mirror, and the number of optical axes can also be easily changed. 4. Description of the drawings] Fig. 1 is an overall configuration diagram of the present invention, Figs. 2 to 7 show examples thereof, Fig. 2 is a front view of the optical system of the detection section, and Fig. 3 Figure 4 is a block diagram of the safety device, Figure 5 is a connection diagram of the welding detection path, Figure 6 is a flowchart showing the operation of the detection section, and Figure 7 is a flowchart showing the operation of the control section. It is. 1... Laser oscillator, 2... Rotating mirror, 3... Parabolic mirror, 4... Half mirror 1, 5... Light receiver, 6... Light projection scanning processing means. 7... Light reception processing means, 8... Optical axis determination means, 9... Stop command means, 10... Detection section, 20... Control section. Patent application Toyo Electronics Co., Ltd. Figure 2 Figure 6

Claims (1)

[Claims] A reflector and a parabolic mirror are arranged to face each other, and a rotating mirror is arranged approximately near the focal point of the parabolic mirror, so as to generate a large number of parallel optical axes between the reflector and the parabolic mirror. It has a laser oscillator that irradiates laser light toward the rotating mirror, a light receiver that receives the laser light on the optical axis via a half mirror, a detection unit that generates light reception data, and a detection unit that generates light reception data from the detection unit. and a control section that outputs a stop signal to stop the machine tool when the optical axis is blocked, and the detection section is configured to drive the laser oscillator and output a laser beam. light emitting and scanning processing means for emitting light and scanning the optical axis by rotationally driving the rotary mirror by a predetermined angle at a time by a motor; and light receiving processing for outputting a received light data signal based on the received light signal sent from the light receiver. The control unit includes an optical axis determination unit that determines whether or not all optical axes are being received based on the received light data signal sent from the detection unit, and outputting a stop signal when all optical axes are not being received. A safety device for a machine tool, which is provided with a stop command means for commanding the machine tool to stop.