JPS63180796A - Safety device for machine tool - Google Patents

Abstract

(57) [Summary] 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 a stop system that 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 invention relates to a light beam type safety device that generates a signal.

<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. When at least one of the multiple optical axes is blocked, the machine tool is stopped because 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. This invention provides a safety device for a machine tool that can generate a large number of optical axes at narrow intervals and can reliably ensure the safety of the machine tool, and is configured as follows.

- That is, the machine tool safety device of the present invention, as shown in the overall configuration diagram of FIG. A reflector 12 is disposed, and a rotating mirror 2 is disposed facing the reflector 12 near the corners of the other two sides facing one side and the other side of the monitored area A, and the rotating mirror 2 and the reflector 12 are disposed opposite to the reflector 12. A laser oscillator 1 that irradiates a laser beam toward the rotating mirror 2 so as to generate a radial optical axis is disposed between the laser oscillator 1 and the laser beam that is reflected by the reflector 12 and returns on the incident optical axis. A detection unit 10 which is provided with a light receiver 5 that receives light through a half mirror 4, and a stop unit that inputs the received light data sent from the detection unit 10 and stops the machine tool when the optical axis is blocked. a control unit 20 that outputs a signal;
The detection unit 10 includes a light projection device 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 scanning processing means 6 and a light receiving processing means 7 for outputting a received light data signal based on the received light signal sent from the light receiver 5 are provided, and the control section 20 is provided with a scanning processing means 6 and a light receiving processing means 7 for outputting a received light data signal based on the received light data signal sent from the detecting section 10. Optical axis determining means 8 determines whether or not light is being received from the optical axis, and stop command means 9 is provided which outputs a trust signal and instructs the machine tool to stop if not all optical axis light is being received.

Therefore, when the rotating mirror 2 is synchronously rotated by a predetermined angle while emitting a laser beam from the laser oscillator 1, the laser beam is reflected by the rotating mirror 2, and the laser beam is reflected by the rotating mirror 2. The laser beam is irradiated onto the opposing reflectors 12 at regular angular intervals while changing its incident angle, and a radial optical axis is formed in the monitored area A between the rotary mirror 2 and the reflector 12 by this laser beam scanning.

At this time, the laser beams on each optical axis are reflected by the reflector 12, return on the incident optical axis again, pass through the rotating mirror 2, and are 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, and light reception data is created for each scan. It is determined whether any of the optical axes is blocked and all optical axes are not receiving light, the stop command means 9 outputs a stop signal to the machine tool.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

The optical system of the detection part of the safety device is the second one. The upper reflector 12a is configured as shown in FIG. 3, and the upper reflector 12a is arranged so that its respective ends are continuous with the front side of the dangerous area of the machine tool, that is, the upper side and right side of the area to be monitored, and the corner where the upper and right sides touch. , vertical part reflector 12b corner part reflector 12
c is provided. And reflectors 12a, 12
b, 12c are the laser oscillator 11 rotating mirror 2. Along with the half mirror 4, the light receiver 51, the rotating mirror motor 11, etc.
An optical system is formed in which the entire area of the monitored area A is used as a scanning area.

The upper reflector 12a, the vertical reflector 12b, and the corner reflector 12c are recursive reflectors that reflect the light emitted from the person onto the same optical axis as the incident light. According to experimental results, it has been confirmed that the reflectors 12a, 12b, and 12C reflect incident light with sufficient reflectance on the incident optical axis when the angle of incidence on the reflector is 40 degrees or more. In the embodiment, the aspect ratio of the monitored area A is 1:1.
A corner reflector 12c is provided so that the upper reflector 12a is continuous with the right end of the upper reflector 12a, and its right side is inclined downward by about 15 degrees, and is continuous with the right end of the corner reflector 12c. A vertical reflector 12b is disposed in a hanging manner. As a result, the incident light from the rotating mirror 2 is directed to each of the reflectors 12a, 12b,
Any part of the beam 12c is formed to have an incident angle of 42 degrees or more.

In the embodiment, the rotating mirror 2 has four reflective surfaces around it, and is formed to be accurately rotated by a constant angle by a rotating mirror motor 11 (for example, a stepping motor). The rotating mirror 2 is disposed near the corner where the lower side and the left side of the monitored area A touch, and the line connecting the rotating mirror 2 and the left end of the upper reflector 12a, and the line between the rotating mirror 2 and the vertical reflector 12b. A substantially quadrilateral monitored area A is formed surrounded by a line connecting the lower ends and each of the reflectors 12a, 12b, and 12c.

The laser oscillator 1 is made of a He-Ne gas laser, a semiconductor laser, or the like, and irradiates a laser beam toward a predetermined position of a rotating mirror 2, and projects the laser beam reflected from the rotating mirror 2 onto reflectors 12a, 12b, and 12c. It is arranged so that it is illuminated.

Then, as the rotating mirror 2 rotates, the laser beam sequentially moves from the lower end to the upper end of the vertical reflector 12b and is projected, and then passes through the corner reflector 12c to the right end of the upper reflector 12a. The light is projected sequentially moving from the center to the left end. The laser beam optical axis is the upper reflector 12
When reaching the left end of point a, the next reflective surface of the rotating mirror 2 arrives, and the laser beam is reflected by that reflective surface and projected onto the lower end of the vertical reflector 12. Then, the above process is repeated further.

Between the laser oscillator 1 and the rotating mirror 2, a condensing lens and a half mirror 4 inclined at about 45 degrees with respect to the optical axis are disposed. Further, on the side of the half mirror 4, a light receiver 5 (for example, a photodiode, a phototransistor, etc.) is irradiated with light from the laser oscillator 1 through a lens, and each reflector 12a.

It is arranged so as to receive the laser light reflected from 12b and 12c and returned through the half mirror 4.

As shown in the block diagram of FIG. 4, the safety device scans the laser beam by rotating the rotating mirror 2.
and each reflector 12a, 12b.

It has a light receiver 5 that receives the laser light generated between 12C and returns on the optical axis via a half mirror 4, and a detection unit 10 that generates one piece of light reception data of the scanning area, and a detection unit 10 that manually collects the light reception data from the detection unit 10. The control section 20 outputs a stop signal to stop the machine tool when any of the many optical axes generated by scanning is blocked.

The detection unit 10 uses a so-called one-chip microcomputer as a light emitting scanning processing means and a light receiving processing means,
A CPU 15 that executes light emitting and receiving processing based on a predetermined program, a ROM 16 that stores fixed information such as program data, 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.
The units are connected to each other by a common bus 19, and data and control signals are transmitted. The input/output circuit 18 includes a driver circuit for synchronously driving the rotation mirror motor 11, an amplifier and a filter for amplifying and filtering the received light signal manually input from the light receiver 5, and then converting it into a digital signal. An A/D converter 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 1 is controlled to start and stop by a microcomputer, but is configured to operate continuously while the safety device is in operation. 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 an optical axis is generated to drive the rotating mirror motor 11 by a fixed angle. The optical axis number setting device 13 is used to preset the number of optical axes generated by scanning, and is configured with, for example, a digital switch or a numeric keypad. When 1.5m, each reflector 12a, 12
When generating optical axes at 1 cm intervals at the reflection points b and 12c, the number of optical axes is set to 250.

The control unit 20 includes a microcomputer that takes in the received light data signal from the detection unit 10, determines whether or not all optical axes are received, and outputs a stop signal when a light blockage occurs, and serves as a stop command unit. , a check switch 21 operated to check whether the main relay contacts are welded, a welding detection circuit 22 as shown in FIG. It is equipped with The microcomputer of the control unit 20 is configured using a one-chip microcomputer, similar to that of the detection unit 10 described above, and includes a CPU 24 that executes optical axis determination and stop signal output processing based on a predetermined program; It is equipped with 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, and each unit is interconnected by a common bus 28. . The input/output circuit 27 is connected to the input/output circuit 18 of the detection unit 10 and transmits the synchronization signal and takes in the received light data.The input/output circuit 27 also includes a check switch 21, a welding detection circuit 22, an abnormality detection circuit 23, Auxiliary stop circuit 30 and stop circuit 31 are connected.

The stop circuit 31 is composed of a driver and a main relay, and is configured to operate the main relay in response to a stop signal output from the input/output circuit 27 to stop the machine tool. Auxiliary stop circuit 3
0 consists of a driver and an auxiliary relay, and is configured to operate the auxiliary relay to stop the machine tool if the main relay of the stop circuit 31 malfunctions such as welding.

As shown in the connection diagram in Figure 5, contact 1x of main relay 1x
Contacts a, lxb and contact 2xa of auxiliary relay 2x are connected in parallel between the stop input terminals of the machine tool, and when the main relay is de-energized, contact 1xb is turned on and stopped, and when the auxiliary relay is energized, contact 2xa is connected. turns on and becomes stopped.

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 the energized state, contact IXa is turned 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 part of the machine tool, and the control unit 20 is installed near the control panel of the machine tool, but each of the detection unit 10 and the control unit 20 has a built-in microcomputer. However, since data is transmitted serially, the lines between them may 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, in step 120, the laser oscillator 1 is activated, and the laser oscillator 1 oscillates a laser beam. 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 manually 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 at a constant angle. At this time, the laser beam emitted from the laser oscillator 1 passes through the half mirror 4 and is reflected by the rotating mirror 2, and as shown in FIG. reflector 1
This corresponds to 2a, 12b, and 12c. And reflector 12
The laser beams reflected by a, 12b, and 12c return on the same optical axis and pass through rotating mirrors 2. The light passes through the half mirror 4 and is received by the light receiver 5.

When the light receiver 5 receives the laser beam, a light reception signal is output, and the light reception signal is amplified and then passed through a filter circuit to remove the influence of ambient light.In step 150, the light reception signal is output through an A/D converter. The received light signal converted into a digital signal is
It is read into PU15. Then, in step 160, it is determined whether or not light has been received based on the light reception signal, and when it is determined that light has been received when the level of the light reception signal is equal to or higher than a predetermined value, the process proceeds to step 170, where the light reception pulse signal (light reception data) is controlled. output to section 20. On the other hand, in step 160, the light receiver 5
If it is determined that the light is blocked, step 170 is not executed, and the process directly jumps to step 180, where "1" is subtracted from the set number of optical axes, and then it is determined whether or not the subtracted number of optical axes is 0 in step 190. Determine whether

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 rotary mirror motor 11 to further rotate the rotary mirror 2 at a constant angle. Thereby, the laser beam reflected by the rotating mirror 2 is reflected by the reflectors 12a and 12b.

It will be reflected at the next reflection point of 12c, and the next optical axis will be formed immediately next to the optical axis that occurred last time. Then, the laser beam that has returned on the optical axis is received by the light receiver 5 on the same side as described above, and the light reception signal output from the light receiver 5 is converted into a digital value in step 150 and the CPU 1
5, and the CPU 15 determines whether or not light is being received. If the light receiver 5 is in the light receiving state, the CPU 15 sends a light receiving pulse signal to the control unit 20 and further subtracts "1" from the number of optical axes. As described above, steps 140 to 190 are repeated, and when the number of optical axes to be subtracted becomes 0, one scan by the laser beam is completed. Then, the process returns from step 190 to step 130, and after inputting the synchronization signal sent from the control section 20, steps 140 to 190 are repeated, and the scanning of the monitored area A with the laser beam is repeated in the same manner as described above.

Note that the processing in steps 110 to 140 corresponds to the light projection processing means 6, and the processing in steps 150 to 170 corresponds to the light reception processing means 7.

Next, the operation of the control section 20 will be explained based on the flowchart shown in FIG.

First, in step 200, the CPU 24 of the control unit 20
A synchronizing signal is output to the detection section 10, and then in step 210, a light reception pulse signal (light reception data) sent from the detection section 10 is read. Then, in step 220, it is determined whether the check switch 21 that checks the welding of the contacts 1xa and lxb of the main relay for stopping is turned on, and if the check switch 21 is not turned on, then step 2
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, 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, closes the contact 1xa, and opens the contact 1xb, so a stop output is output, but the machine tool is not stopped.

On the other hand, if it is determined in step 230 that there is a light-shielded optical axis and that all the optical axes are not in the light-receiving state, the process proceeds to step 250, in which the output of the safety signal is stopped and the stop circuit 31
The machine tool is stopped by deenergizing the main relay 1x and turning on its contact 1xb. Subsequently, from step 240 or from step 250 to step 26
0, and the main relay contacts 1xa and lx of the stop circuit 31
It is determined whether or not b 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 is finished, and if the main relay contacts are welded, Next, 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 by the manual input of the welding abnormality signal, closes its contact 2xa, and performs stop control, thereby stopping the machine tool.

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 circuit 31. That is, in step 270, the output of the safety signal is stopped and the stop circuit 3
Deenergize main relay 1 and turn on contact 1xb 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, and the contact 2xa
is turned on, and further in step 290, the stop circuit 31 is turned on.
outputs a safety signal to energize the main relay of the stop circuit 31 and turn off the contact 1xb. After turning on and off the contacts of the main relay in this way, the process proceeds to step 300, where the welding detection circuit 22 checks whether the contacts of the main relay are in a welded state.
If the main relay contacts are welded, the process proceeds to step 320 where a welding abnormality signal is output to the auxiliary stop circuit 30 to stop the machine tool. On the other hand, if there is no welding of the contacts of the main relay, then the process proceeds to step 310, where 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.

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 condition of the main relay of the stop circuit 31 is also checked.
If welding is detected, a welding abnormality signal is sent to the auxiliary stop circuit 30.
The auxiliary stop circuit 30 controls the machine tool to stop. Further, when the check switch 21 is turned on, the process advances from step 220 to step 270, and steps 270 to 310 are executed to forcibly turn on and off the contacts of the main relay of the stop circuit 31, and the welded state of the contacts is It should be noted that the process of step 230 corresponds to the optical axis determination means 8,
The process of step 250 corresponds to the stop command means 9.

It should be noted that the present invention is not limited to the configuration of the above-described embodiments, and the embodiments thereof can be modified without departing from the technical idea of the present invention. For example, the reflectors 12a, 12b, and 12c in the embodiment may be formed by bending a single reflector. Also, whether the monitored area A is square or has an aspect ratio of 1:1.
．． If the reflector is rectangular in size up to about 2, it can be configured with two consecutive reflectors, an upper reflector and a vertical reflector, or a bent L-shaped reflector.

<Effects of the Invention> As explained above, according to the machine tool safety device of the present invention, since the optical axis is generated by a laser beam, the beam can be projected 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 large and does not spread, and the optical axis gap can be set narrow, allowing for narrow-eyed monitoring.Furthermore, the rotating mirror allows for radial light. Since the laser beam that generates an axis, is reflected by a reflector, and returns on the same optical path as the emitted light is received via a half mirror, it is only necessary to combine the reflector with one laser oscillator, making the device compact. , can be configured concisely, and
Optical axis adjustment when installing the device becomes extremely easy.

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.

[Brief explanation of the drawing]

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, Fig. 3 is a plan view thereof, and Fig. 4 is FIG. 5 is a block diagram of the safety device, FIG. 5 is a connection diagram of the welding detection circuit, FIG. 6 is a flowchart showing the operation of the detection section, and FIG. 7 is a flowchart showing the operation of the control section. DESCRIPTION OF SYMBOLS 1... Laser oscillator, 2... Rotating mirror, 5... Light receiver, 6... Light emission scanning processing means, 7... Light reception processing means, 8... Optical axis determination means, 9. ...Stop command means, 10...Detection section, 12...Reflector, 20...Control section, A...Monitored area. Figure 1 Figure 6 Gi■D 7rA

Claims (1)

[Scope of Claims] A reflector is continuously arranged on one side of the monitored area forming a substantially quadrilateral shape and another side adjacent to the one side, and a reflector is disposed continuously on one side of the monitored area forming a substantially quadrilateral shape, and a reflector is disposed continuously on one side of the monitored area forming a substantially quadrilateral shape, and another reflector is disposed continuously on one side of the monitored area forming a substantially quadrilateral shape, and another reflector is disposed continuously on one side of the monitored area forming a substantially quadrilateral shape and on the other side adjacent to the one side. A laser oscillator in which a rotating mirror is disposed near the corners of two sides facing the reflector, and irradiates laser light toward the rotating mirror so as to generate a radial optical axis between the rotating mirror and the reflector. is provided with a detection unit that is provided with a light receiver that receives the laser beam reflected by the reflector and returned on the incident optical axis via a half mirror, and inputs the light reception data sent from the detection unit, The safety device includes a control unit that outputs a confidence signal to stop the machine tool when the optical axis is blocked, and a control unit that drives the laser oscillator to project a laser beam to the detection unit. light emitting and scanning processing means for emitting light and scanning the optical axis by rotationally driving the rotary mirror by a predetermined angle by a motor; and light reception processing means for outputting a light reception data signal based on the light reception 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 detecting unit, and if all optical axes are not being received, a stop signal is output and the operation is performed. A safety device for a machine tool, characterized in that it is provided with a stop command means for commanding the machine to stop.