Safety devices

Abstract

To provide a safety device capable of accurately managing the safety of a processing machine by avoiding erroneous detection of light other than light emitted from a projector. [Solution] The safety device 50 includes a light-emitter 60 that emits detection light LB at predetermined time intervals, a light-receiver 70 that outputs a determination signal Sd2 indicating whether a light-receiving element 80 detects light, and a safety control unit 102. The safety control unit 102 determines whether the light-receiving element 80 detects light based on the determination signal Sd2 output from the light-receiver 70 during each period in which the detection light LB is not emitted from the light-emitter 60, and if it determines that the light-receiving element 80 has detected light, it stops the operation of the processing machine and stops the emission of the detection light LB from the light-emitter 60. If it subsequently determines that the light-receiving element 80 has not detected light, it resumes the emission of the detection light LB from the light-emitter 60 and restores the processing machine to an operable state.

Description

[Technical Field]

[0001] The present invention relates to a safety device. [Background technology]

[0002] Bending machines (press brakes) are equipped with a safety device that detects obstacles by detecting whether a light beam is interrupted. This safety device has a light emitter that emits a light beam (detection light) to detect obstacles, and a light receiver that receives the detection light emitted from the light emitter. If the detection light emitted from the light emitter is not received by the light receiver, the press brake determines that there is an obstacle in the monitoring area, that is, an abnormal state, and stops the processing operation.

[0003] In the safety device described above, a method is known in which a pulsed light beam that blinks at a predetermined frequency is used as the detection light. This method has the following advantages: (a) even when ambient light interferes, the difference in the frequency of the light beam can be used to distinguish between the ambient light and the detection light, and (b) it is possible to monitor whether the light receiving state of the detection light at the receiver remains stuck on the ON side (light receiving side) or the OFF side (light blocking side).

[0004] Furthermore, Patent Document 1 discloses a technology in which two safety devices that emit pulsed light beams of the same design are installed side by side, and even if the detection light output from both light emitters interferes with each other at the receivers, each safety device can accurately determine an abnormal state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-137868 Summary of the Invention [Problem to be solved by the invention]

[0006] When a monochromatic laser beam is used in the safety device described above, the laser beam may "fluctuation" depending on the operating environment. This "fluctuation" is a phenomenon in which the refraction of the laser beam creates areas of high light intensity.

[0007] If the strong light intensity caused by this "fluctuation" enters the receiver of the safety device as a disturbance, it can interfere with the monitoring process described above in (b), and the receiver may mistakenly recognize that the detection light is stuck on the ON side, even though it is not actually stuck. In this case, the press brake will be judged to have experienced an abnormality and will stop, making it impossible to resume operation without restarting, causing inconvenience to the user. [Means for solving the problem]

[0008] A safety device according to one aspect of one or more embodiments is a safety device that manages the safety of a processing machine performing specified work, and includes a light-projector that emits a light beam at predetermined time intervals, a light-receiver that includes a light-detecting element that detects light and outputs a determination signal indicating whether the light-receiving element detects light, and a safety control unit that determines whether the light-receiving element detects light based on the determination signal output from the light-receiver for each period in which a light beam is not emitted from the light-projector, and if it determines that the light-receiving element has detected light, stops the operation of the processing machine and stops the emission of the light beam from the light-projector, and if it determines that the light-receiving element has not detected light based on the determination signal output from the light-receiver after the emission of the light beam has been stopped, resumes the emission of the light beam from the light-projector and restores the processing machine to an operable state. [Effects of the Invention]

[0009] According to the safety device of one or more embodiments, it is possible to avoid erroneous detection of light other than the light beam emitted from the projector, and to accurately manage the safety of the processing machine. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of a press brake to which a safety device according to this embodiment is applied. [Figure 2] FIG. 2 is a block diagram showing the configuration of the safety device according to this embodiment. [Figure 3] FIG. 3 is a flowchart showing the operation of the safety device when the press brake is in operation. [Figure 4] Figure 4 is a timing chart showing the time-dependent changes in the operating status of various devices within the press brake that are recognized when temporary fluctuations in the detection light occur while the press brake is in operation. [Figure 5] FIG. 5 is a timing chart showing the time-dependent changes in the operating states of various devices within the press brake that are recognized when an abnormality occurs in the safety device while the press brake is in operation. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a case where a safety device according to one or more embodiments is applied to a press brake will be described with reference to the accompanying drawings. First, a schematic configuration of the press brake will be described using FIG. 1. The press brake 1 is a processing machine that performs a prescribed operation of bending a plate-shaped workpiece (sheet metal) W using a pair of dies (punch and die). The press brake 1 includes an upper table 10, a lower table 20, and a press brake control device 30.

[0012] The upper table 10 holds a punch 14, which is an upper die. Specifically, an upper die holder (not shown) is attached to the upper table 10, and the punch 14 is attached to the upper die holder.

[0013] The upper table 10 is configured to move up and down by raising and lowering actuators 11L, 11R, which are provided on the left and right sides and use hydraulic cylinders. Each of the actuators 11L, 11R is mainly composed of a pump and a motor. The vertical position of the upper table 10 is detected by a position detection unit such as a linear encoder (not shown). Position information detected by the position detection unit is supplied to the press brake control device 30. The actuators 11L, 11R are not limited to hydraulic cylinders, and electric motors may also be used.

[0014] The lower table 20 is provided below the upper table 10. The lower table 20 holds a die 24, which is a lower mold. Specifically, a lower mold holder (not shown) is attached to the lower table 20, and the die 24 is attached to the lower mold holder. For example, a workpiece W is placed on the die 24. When the upper table 10 is lowered, the workpiece W is sandwiched between the punch 14 and the die 24 and bent.

[0015] The press brake control device 30 can be configured with an NC device. The press brake control device 30 raises or lowers the actuators 11L, 11R. The press brake control device 30 controls the vertical position of the upper table 10 based on position information detected by a position detection unit. Furthermore, when a safety signal OFF is supplied from the safety control device 100 as described below, the press brake control device 30 stops the lowering of the upper table 10 and interrupts the bending of the material by the press brake.

[0016] The press brake 1 further includes a safety device 50 that manages the safety of the press brake 1 by monitoring the intrusion of foreign matter (intrusion object) other than the workpiece W into the protection area between the punch 14 and the die 24. The safety device 50 is mainly composed of a light projector 60, a light receiver 70, and a safety control device 100.

[0017] The light projector 60 is attached, for example, via an arm 15R, to the right side of the upper table 10. The light projector 60 emits detection light LB at predetermined time intervals so that the detection light LB passes between the punch 14 and the die 24.

[0018] The light receiver 70 is attached, for example, via an arm 15L to the left side of the upper table 10. The light receiver 70 is disposed in a position facing the light projector 60. The light receiver 70 receives detection light that has passed between the punch 14 and the die 24.

[0019] The safety control device 100 is a control device that controls the safety device 50. The safety control device 100 controls the light projector 60 and the light receiver 70. Furthermore, when the safety control device 100 determines, based on information acquired from the light receiver 70, that no foreign object has entered the protection range, it supplies a safety signal ON (operation permission signal) to the press brake control device 30. On the other hand, when the safety control device 100 determines that a foreign object has entered the protection range, it supplies a safety signal OFF (operation stop signal) to the press brake control device 30.

[0020] The specific configuration of the safety device 50 will be described with reference to Fig. 2. The projector 60 outputs detection light LB. The detection light LB is, for example, a laser beam. The projector 60 is composed of a laser light source and a collimating lens that adjusts the beam light emitted by the laser light source to a parallel state.

[0021] The light receiver 70 is composed of a light receiving element 80 and a determination unit 90.

[0022] The light receiving element 80 detects light having an intensity equal to or greater than a predetermined value, including the detection light LB. When the light receiving element 80 detects light having an intensity equal to or greater than a predetermined value, it outputs a detection signal (electrical signal) Sd1. The detection signal Sd1 output from the light receiving element 80 is output to the determination unit 90. The light receiving element 80 can be configured with a photodiode or a two-dimensional imaging element. The two-dimensional imaging element is, for example, a CCD (Charge Coupled Device).

[0023] The determination unit 90 determines whether the light receiving element 80 is in a light receiving state where it detects (receives) the detection light LB, or in a light blocking state where it does not detect the detection light LB, based on the detection result of the light receiving element 80. The determination unit 90 outputs a determination signal Sd2 indicating the determination result to the safety control device 100.

[0024] In this embodiment, the light receiver 70 is integrated with a light receiving element 80 and a determination unit 90. However, the determination unit 90 may be provided outside the light receiver 70. For example, the determination unit 90 may be configured as a part of the safety control device 100.

[0025] The safety control device 100 is mainly composed of a CPU, a ROM, a RAM, and an I / O interface. The safety control device 100 controls the operation of the safety device 50 by having the CPU read out various programs corresponding to the processing content from the ROM or the like, expanding them in the RAM, and executing the various expanded programs.

[0026] Functionally, the safety control device 100 includes a light projection control unit 101 and a safety control unit 102.

[0027] The light-projection control unit 101 controls the projector 60 to control the detection light LB emitted from the projector 60. The light-projection control unit 101 outputs a control signal Sc to the projector 60. The projector 60 turns on in response to the control signal Sc being on, and turns off in response to the control signal Sc being off.

[0028] The safety control unit 102 determines the safety state of the press brake 1 based on the determination signal Sd2 output from the determination unit 90 and the operating state of the press brake 1. The safety control unit 102 controls the state of the safety signal to be supplied to the press brake control device 30 based on the confirmed safety state. The safety control unit 102 manages the safety of the press brake 1 by automatically stopping the press brake 1 in accordance with the state of the safety signal.

[0029] In this embodiment, the safety control device 100 is configured with a CPU or the like, and controls the safety device 50 by software processing. However, the safety control device 100 may be configured with a hardware circuit, and the safety device 50 may be controlled by the hardware circuit.

[0030] A description will be given of light blocking monitoring, which is a basic operation of the safety device 50 according to this embodiment. Light blocking monitoring refers to an operation of outputting detection light LB from the projector 60 and monitoring whether this detection light LB is blocked.

[0031] Prior to light blocking monitoring, the light-projection control unit 101 starts light-projection processing. When the light-projection processing starts, the light-projection control unit 101 outputs a pulse-like control signal Sc that turns on and off at a predetermined frequency. The light-projector 60 emits detection light LB of a predetermined frequency at predetermined time intervals in response to the on / off of the control signal Sc from the light-projection control unit 101, thereby causing it to blink. By the light-projector 60 blinking the detection light LB in this way, the safety device 50 can recognize that no abnormality has occurred due to the light-receiving state of the light-receiver 70 being stuck on the on side (light-receiving side) or off side (light-blocking side), and that the safety device 50 is operating normally.

[0032] The detection light LB output from the light projector 60 passes between the punch 14 and the die 24 and is incident on the light receiving element 80 of the light receiver 70. When the light receiving element 80 receives the detection light LB of a predetermined frequency, it outputs a detection signal Sd1 according to the intensity of the incident detection light LB.

[0033] The determination unit 90 receives a detection signal Sd1 from the light-receiving element 80 in accordance with the projection period of the detection light LB. Based on the presence or absence of the detection signal Sd1 from the light-receiving element 80, the determination unit 90 determines whether the light-receiving element 80 is in a light-receiving state in which it receives the detection light LB, or in a light-blocking state in which it does not receive the detection light LB.

[0034] Specifically, when the light-receiving element 80 receives the detection light LB and outputs a detection signal Sd1 having a voltage value equal to or greater than a predetermined value, the determination unit 90 determines that the light-receiving state is established. Then, the determination unit 90 outputs a determination signal Sd2 indicating the determination result, which is "1" indicating that the detection light LB is not blocked. On the other hand, when the light-receiving element 80 does not receive the detection light LB and does not output a detection signal Sd1 having a voltage value equal to or greater than a predetermined value, the determination unit 90 determines that the light-blocking state is established. Then, the determination unit 90 outputs a determination signal indicating the determination result, which is "0" indicating that the detection light LB is blocked.

[0035] The safety control unit 102 confirms the safety state of the press brake 1 based on the determination signal Sd2 output from the determination unit 90 and the operating state of the press brake 1. Based on the confirmed safety state, the safety control unit 102 generates and outputs a safety signal (OSSD: Output Signal Switching Device) that determines whether or not to stop the descent of the upper table 10. If the safety signal has a value of "1" (ON), it indicates that the operation of continuing the descent of the upper table 10 without stopping it is permitted, and if the value is "0" (OFF), it indicates that the operation of stopping the descent of the upper table 10 is not permitted.

[0036] If the detection light LB is not blocked by an intruding object such as a hand, the judgment signal from the judgment unit 90 will be "1." Therefore, the safety control device 100 outputs a value of "1" as a safety signal. On the other hand, if the detection light LB is blocked by an intruding object such as a hand, the judgment signal from the judgment unit 90 will be "0." Therefore, the safety control device 100 outputs a value of "0" (off) as a safety signal. When the safety control unit 102 outputs a safety signal of "0," the press brake control device 30 stops the descent of the upper table 10 and interrupts the bending of the material by the press brake 1.

[0037] Furthermore, the safety control unit 102 monitors the light receiving state of the detection signal Sd1 and determines whether the light receiving state remains stuck on the ON side or the OFF side. Through such determination, the safety control unit 102 can detect a failure of the safety device 50.

[0038] 3 to 5, the operation of the safety device 50 will be described along with a series of operations of the press brake 1. FIG. 3 is a flowchart showing the operation of the safety device 50 when the press brake 1 is in operation. FIG. 4 is a timing chart showing changes over time in the operating states of various devices within the press brake 1, which are recognized when a temporary fluctuation in the detection light LB occurs while the press brake 1 is in operation. FIG. 5 is a timing chart showing changes over time in the operating states of various devices within the press brake 1, which are recognized when an abnormality occurs in the safety device 50 while the press brake 1 is in operation.

[0039] In the initial state, the light projection processing function of the light projection control unit 101 is in an ON state, that is, in a state in which the light projection processing is being executed. During the execution of the light projection processing, the projector 60 blinks by repeatedly turning on (emitting the detection light LB) and off every predetermined period Pr in response to the ON / OFF of the control signal Sc output by the light projection control unit 101.

[0040] Furthermore, based on the safety state of the press brake confirmed in the initial state, the safety signal (OSSD) is in the on state, the operation function of the closing pedal (not shown) for instructing the press brake 1 to perform a processing operation, specifically, for lowering the upper table 10 when processing the workpiece W, is valid, and the closing pedal is kept depressed (on state).

[0041] On the other hand, the light-receiving element 80 of the light receiver 70 outputs a detection signal Sd1 when it detects the detection light LB emitted from the light-projector 60. The light-receiving element 80 outputs the detection signal Sd1 not only when it detects the detection light LB emitted from the light-projector 60, but also when it detects disturbance light of an intensity equal to or greater than a predetermined value due to fluctuations in the detection light LB or the like.

[0042] The fluctuation of the detection light LB occurs when, for example, the temperature of the mold (punch 14 or die 24) rises while the press brake 1 is in use, causing variations in density between the temperature of the mold and the air, which causes the detection light LB to be refracted, resulting in the light being concentrated in a part of the space and increasing the intensity of the light. This fluctuation of the detection light LB occurs temporarily due to the emission of the detection light LB, and will subside when the emission of the detection light LB stops.

[0043] The determination unit 90 determines whether the light receiving element 80 is in a light receiving state or a light blocking state based on whether or not the detection signal Sd1 is output from the light receiving element 80. When the detection signal Sd1 is output, the determination unit 90 determines that the light receiving element 80 is in a light receiving state, and outputs "1" as the determination signal Sd2. When the detection signal Sd1 is not output, the determination unit 90 determines that the light receiving element 80 is in a light blocking state, and outputs "0" as the determination signal Sd2.

[0044] The process executed by the safety control unit 102 when a temporary fluctuation in the detection light LB occurs during the execution of the above-described light-projection process will be described with reference to Fig. 4. During each periodically occurring extinguishing period in which the detection light LB is not emitted from the projector 60, the safety control unit 102 determines whether or not light is detected by the light-receiving element 80, based on the determination signal Sd2 sequentially output from the light-receiver 70 (times t1, t2, ... in Fig. 4).

[0045] At times t1 and t2, since the light receiving element 80 does not detect light, the determination unit 90 outputs a determination signal Sd2 of "0", and the OSSD output remains in the ON state.

[0046] Thereafter, when the light receiving element 80 detects light and the determination signal Sd2 becomes "1" a predetermined number of times in succession ("YES" in S1), the safety control unit 102 switches the OSSD to the OFF state and outputs message information from a connected display device (not shown) indicating that the operation of the press brake 1 will be stopped (S2, time t13). Here, when the OSSD is in the OFF state, the operation of the close pedal is invalid, so the press brake 1 does not operate.

[0047] Furthermore, when the safety control unit 102 switches the OSSDs to the OFF state, it stops the emission of the detection light LB from the transmitter 60 by switching the light-projection processing function of the light-projection control unit 101 to the OFF state (S3, time t13). Note that the safety control unit 102 may switch the OSSDs to the OFF state after switching the light-projection processing function of the light-projection control unit 101 to the OFF state.

[0048] Even after the emission of the detection light LB is stopped, the safety control unit 102 periodically monitors the judgment signal Sd2 output sequentially from the light receiver 70, and determines whether or not light is detected by the light receiving element 80 (times t14, t15, etc.).

[0049] Here, if the reason why the determination signal Sd2 has become "1" a predetermined number of times in succession is due to the occurrence of temporary fluctuations caused by the detection light LB, the fluctuations will disappear when the projector 60 is turned off. When the fluctuations disappear, the light receiving element 80 will no longer detect light, and thereafter the determination unit 90 will output the determination signal Sd2 "0".

[0050] When the safety control unit 102 recognizes that the judgment signal Sd2 "0" has been output a predetermined number of times in succession (time t16), it determines that the safety device 50 has returned to a normal state ("YES" in S4) and resumes the light projection process from the projector 60 by the light projection control unit 101 (S5).

[0051] Furthermore, when it is determined that the safety device 50 has returned to the normal state, the OSSD outputs are switched from the OFF state to the ON state a predetermined time after they have been switched to the OFF state (time t21). When the safety device 50 has returned to the normal state and the OSSD outputs have been switched to the ON state, the safety control unit 102 becomes able to operate the close pedal.

[0052] When it is detected that the worker has operated the close pedal in response to this ("YES" in S6, time t23), the safety control unit 102 outputs an instruction to erase the message information output in step S2. Also, because the OSSD output is in the ON state, the operation of the close pedal is valid, and when the close pedal is operated, the table operation is started by the press brake control device 30, and the press brake 1 returns to its normal state (S7).

[0053] 5, a process executed by the safety control unit 102 when an abnormality occurs in the safety device 50 during the light projection process will be described. As in the case of FIG. 4, when the processes of steps S1 to S3 are executed and an abnormality occurs in which the light reception state of the light receiver 70 is stuck on the ON side, the safety control unit 102 determines in step S4 that the determination signal Sd2 "0" has not been output a predetermined number of times in succession and that an abnormality has occurred in the safety device 50 ("NO" in S4, time t52), and outputs an alarm as an abnormality occurrence signal (S7). In this case, the close pedal remains in the disabled state, and therefore, even if the close pedal is operated, this operation is not accepted and the bending process is not performed.

[0054] In the above-described embodiment, the safety control unit 102 may be configured to include two systems of a first control unit and a second control unit, and the judgment signal Sd2 output sequentially from the photodetector 70 may be alternately acquired by the first control unit and the second control unit.

[0055] In this configuration, the timing at which the OSSDs are switched to the OFF state, as determined in step S2, can be set, for example, as follows. (1) When the first control unit or the second control unit acquires the determination signal Sd2 "1" a predetermined number of times in succession. (2) When the cumulative number of times the determination signal Sd2 "1" is acquired in the first control unit and the second control unit becomes equal to or greater than a predetermined value.

[0056] Furthermore, in this configuration, the timing at which the safety device 50 has returned to the normal state, which is determined in step S4, can be set, for example, as follows. (3) When the first control unit and the second control unit obtain the determination signal Sd2 "0" a predetermined number of times in succession.

[0057] By performing the processing as described above, the redundancy of the safety device 50 can be improved.

[0058] [Effects of the embodiment] According to the above-described embodiment, the safety device is a safety device that manages the safety of a processing machine performing a specified operation, and includes a light-emitter that emits a light beam at predetermined time intervals, a light-receiver that includes a light-detecting element that detects light and outputs a determination signal indicating whether the light-receiving element detects light, and a safety control unit. The safety control unit determines whether the light-receiving element detects light based on the determination signal output from the light-receiver during each period in which a light beam is not emitted from the light-emitter, and if it determines that the light-receiving element has detected light, stops the operation of the processing machine and stops the emission of the light beam from the light-emitter. If it determines that the light-receiving element has not detected light based on the determination signal output from the light-receiver after the emission of the light beam has stopped, it resumes the emission of the light beam from the light-emitter and restores the processing machine to an operable state.

[0059] This makes it possible to avoid false detection due to light other than the light beam emitted from the projector or disturbances, and to accurately manage the safety of the processing machine.

[0060] Furthermore, if the safety control unit determines that the light receiving element has detected light based on the determination signal output from the light receiver after stopping the emission of the light beam, it outputs an abnormality occurrence signal, thereby making it possible to properly notify the user when an abnormality has occurred in the safety device.

[0061] The safety control unit may also periodically monitor the determination signal output from the light receiver during a period when the light emitter is not emitting light, and determine that the light receiving element is detecting light when it recognizes that the light receiving element has detected light a predetermined number of times in succession. This allows the light receiving element to perform light detection processing with high accuracy.

[0062] Furthermore, the processing machine may be a bending machine, and the safety control unit may stop operation of the bending machine by disabling a processing operation instruction to the bending machine when emission of the light beam from the projector is stopped, and may return the bending machine to an operable state by enabling a processing operation instruction to the bending machine when emission of the light beam from the projector is resumed. This allows management to be performed so that the bending machine can be operated safely.

[0063] The safety control unit may also be composed of two systems, a first control unit and a second control unit, and the judgment signals output sequentially from the receiver may be alternately acquired by the first control unit and the second control unit, and when the first control unit or the second control unit acquires a judgment signal indicating that the light receiving element has detected light a predetermined number of times in succession, or when the cumulative number of times that the first control unit and the second control unit have acquired a judgment signal indicating that the light receiving element has detected light reaches or exceeds a predetermined value, the safety control unit may stop emitting light from the light projector and stop operation of the processing machine.

[0064] Furthermore, the safety control section may resume emission of the light beam from the projector and restore the processing machine to an operable state when the first control section and the second control section receive a determination signal indicating that the light receiving element has not detected light a predetermined number of times in succession. This allows the redundantly configured safety device to appropriately perform light detection processing using the light receiving element.

[0065] In the above-described embodiment, the safety device 50 has been described as avoiding erroneous detection of an abnormality occurring when the light receiving state of the detection light in the light receiver is stuck on the on side (light receiving side), but this is not limited to this, and it can also be applied to erroneous detection of an abnormality occurring when crosstalk failure occurs between multiple light receiving elements.

[0066] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0067] 1. Press brake 10 Upper table 11L, 11R actuators 14 Punch 15L, 15R arms 20 Lower Table 24 Die 30 Press brake control device 50 Safety equipment 60 Floodlight 70 Receiver 80 Photodetector 90 Judgment section 100 Safety control device 101 Light projection control unit 102 Safety control section

Claims

1. A safety device that manages the safety of a processing machine that performs specified work, a projector that emits light rays at predetermined time intervals; a light receiver including a light receiving element for detecting light and outputting a determination signal indicating whether the light receiving element detects light; and a safety control unit that, during each period in which a light beam is not emitted from the light projector, determines whether or not the light receiving element has detected light based on a determination signal output from the light receiver, and if it determines that the light receiving element has detected light, stops operation of the processing machine and stops emission of the light beam from the light projector, and if it determines that the light receiving element has not detected light based on the determination signal output from the light receiver after emission of the light beam has been stopped, resumes emission of the light beam from the light projector and returns the processing machine to an operable state.

2. 2. The safety device according to claim 1, wherein the safety control unit outputs an abnormality occurrence signal when it determines that the light receiving element has detected light based on a determination signal output from the light receiver after stopping the emission of the light beam.

3. 2. The safety device according to claim 1, wherein the safety control unit periodically monitors the determination signal output from the light receiver during a period in which no light is emitted from the light emitter, and when it recognizes that the light receiving element has detected light a predetermined number of times in succession, it determines that the light receiving element has detected light.

4. the processing machine is a bending machine, The safety control unit stops the operation of the bending machine by disabling a processing operation instruction to the bending machine when the emission of the light beam from the floodlight is stopped, and restores the bending machine to an operable state by enabling a processing operation instruction to the bending machine when the emission of the light beam from the floodlight is resumed.

5. The safety control section is composed of two systems of a first control section and a second control section, and the determination signals sequentially output from the light receivers are alternately acquired by the first control section and the second control section, When the first control unit or the second control unit acquires a determination signal indicating that the light receiving element has detected light a predetermined number of times in succession, or In the first control unit and the second control unit, when the cumulative number of times that a determination signal indicating that the light receiving element has detected light reaches a predetermined value or more, 2. The safety device according to claim 1, wherein the safety device stops the emission of the light beam from the light projector and stops the operation of the processing machine.

6. 6. The safety device according to claim 5, wherein the safety control unit resumes emission of light from the light projector and restores the processing machine to an operable state when the first control unit and the second control unit acquire a determination signal indicating that the light receiving element has not detected light a predetermined number of times in succession.

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