JP5055799B2 - Safety switch - Google Patents

Description

  The present invention relates to a safety switch as a key switch used for a door switch or the like.

  In general, a door switch detects the opening / closing of a door provided at the entrance / exit of a work area where an automated machine tool is installed, and turns on / off the machine tool. When the door is closed, an operation key provided on the door side Is inserted into the switch body provided on the entrance / exit side, the internal cam is rotated by the inserted operation key, the switch part built in the switch body is switched to the switch-on state, the power circuit is connected, and the door When the door is opened, the internal cam is rotated by pulling out the operation key, the switch part is switched to the switch-off state, and the power supply circuit is cut off.

  As an electromagnetic lock type door switch, when the door is closed, the lock energized lock mechanism is activated and the lock is automatically applied. The door can be opened by energizing the electromagnetic solenoid and unlocking the lock mechanism. When the door is closed, the lock is not applied immediately, and the lock mechanism that is energized to unlock the electromagnetic solenoid is activated to maintain the locked state. There is known a solenoid lock type that releases the energization of the door to release the bias and allows the door to open.

  In any of the above-described methods, if the door is forcibly opened without being unlocked, the internal cam is forced to rotate by pulling out the operation key. Or the plunger operated by this, the cam rotates, the operation key is pulled out and the door opens, and this damage keeps the switch part in the switch-on state and the door opens. In spite of this, there is a problem that the power supply circuit remains connected and the machine tool remains operating.

  As a conventional safety switch that eliminates such problems, multiple cam members are rotated by inserting operation keys, and multiple plungers linked to each cam member move to operate multiple switch units linked to each plunger. And a lock switch that operates the lock mechanism to lock the plunger. The key switch includes a plurality of cam members, plungers, and switch parts, and at least one of the plurality of plungers. There is one that is not locked (see Patent Document 1).

  According to this safety switch, when an inexperienced operator tries to forcibly open the door of a protective fence of equipment such as a machine tool, a force in the pulling direction of the operation key is applied to the cam member. An unreasonable force acts on the plunger as it tries to rotate, but since there are a plurality of cam members and plungers, the unreasonable force applied to the plunger is dispersed. For this reason, the problem that the plunger does not break and the key switch breaks down and the safety is impaired is solved.

  In addition, as a conventional safety switch that solves the above-described problems, the switch part, an operation mechanism that operates forward and reverse by inserting and removing the operation key to switch the switch part to contact, and a contact that is brought about by insertion of the operation key A switch having a lock mechanism for maintaining the switching state, and when a pull-out load more than the setting is applied to the operation key in the locked state in which the contact switching state is maintained, the lock mechanism is forcibly released, and the operation mechanism and Some switch units are switched to the normal contact switching state brought about when the operation key is pulled out to avoid the occurrence of the above-mentioned problems.

  In this case, the switch unit is in a switch-on state in which the movable terminal contacts the fixed terminal when the movable member that supports the movable terminal facing the fixed terminal is biased and displaced by the return spring, and the movable member is a double return spring. When the operation key is pulled out, the operation mechanism moves to the switch-off position against the return biasing force. When the operation key is inserted, the switch portion is displaced to the switch-on position by the return biasing force.

The lock mechanism engages the lock member with the movable member or the plunger so that the lock member is in a locked state. At least a part of the lock member is weaker than the movable member or the plunger, and is set to the key in the locked state or more. When the extraction load is applied, the lock member is deformed and damaged, and the lock is released (see Patent Document 2).
Japanese Patent Laid-Open No. 2002-216591 JP 2003-45294 A

  In the former conventional safety switch described above, when trying to forcefully open the door of the protection fence of a machine tool or the like, the switch portion is not operated even if the operation key is pulled out due to a failure of the lock mechanism. In order to operate, a plurality of cam members, plungers, and switch parts are provided, and a switch part and a switch operation mechanism for detecting the operation state of the solenoid are required. The cost was hindered.

  In the latter conventional safety switch, the lock mechanism is such that the lock member is engaged with the movable member or the plunger so that the lock member is locked, and at least a part of the lock member is moved from the movable member or the plunger. However, if the extraction load more than the set value is applied to the key in the locked state, the lock member must be deformed and damaged in order for the lock member to be deformed and damaged to be unlocked.

  The present invention has been made by paying attention to the above-mentioned problems, and the object of the present invention is to simplify the configuration, reduce the size and reduce the cost, and set the operation key in the locked state. It is an object of the present invention to provide a safety switch in which the lock member does not always need to be deformed and damaged when the above extraction load is applied, and the fail safe functions and safety can be ensured.

In order to achieve the above object, a safety switch according to the present invention has a switch operation unit for operating a switch unit, and operates the switch unit by inserting and removing an operation key to and from the switch operation unit. A safety switch that opens and closes a circuit. The switch operation section includes first and second cam bodies that rotate by inserting and removing one operation key, and the switch section is turned on and off by rotation of the first cam body. An operation key insertion / extraction detection switch that operates to detect insertion / extraction of the operation key, a lock unit that locks the second cam body when the operation key is inserted, a lock operation unit that operates the lock unit, and the lock operation An unlock actuating means for releasing the lock when the means is actuated, and an on / off actuating operation by the actuating of the lock actuating means and the unlock actuating means to lock the second cam body. Unlocked state and is composed of a locking and unlocking detection switch unit for detecting the, in addition, the operation keys insertion detection switch portion, for failure detection in addition to having a first contact portion which is turned actuated insertion of the operation key It has a contact and the lock / unlock detection switch part has a fault detection contact part in addition to the second contact part that is turned on when the lock member is activated. When the key insertion / extraction detection switch part is activated and the lock / unlock detection switch part is not activated, it is detected by turning on / off both failure detection contacts, and the lock function of the switch body is broken. It is characterized by being detected .

With such a configuration, the operation key is pulled out without operating the lock / unlock detection switch part in the lock function failure state and in the state where the second cam body is locked by the lock means and the operation key is pulled out. In this case, the operation key insertion / extraction detection switch unit can be operated by rotating the first cam body with the operation key. For this reason, fail safe works and safety can be secured. Pressurizing forte, that the lock function of the switch unit is damaged, it is possible to detect both the failure detecting contact of the ON / OFF.

  In addition, unlike the conventional safety switch, there is no need to configure a plurality of cam members, plungers, and switch parts, and the configuration is simple, enabling downsizing and cost reduction. As described above, when an extraction load more than a set value is applied to the key in the locked state, it is not necessary to make at least a part of the lock member more fragile than the movable member or the plunger in order to deform and damage the lock member. Here, the first cam body corresponds to, for example, a drive cam, and the second cam body corresponds to, for example, a lock cam.

The safety switch according to the present invention is the safety switch according to the present invention described above, wherein the first cam body is a drive cam, the second cam body is a lock cam, and the lock means is a lock member. The lock actuating means is configured to actuate the lock member and engage the lock member with the lock cam when the operation key is inserted to lock the rotation of the lock cam. The unlock actuating means is locked when the lock actuating means is actuated. The operation key insertion / extraction detection switch unit rotates the drive cam when the operation key is inserted to turn on the first contact portion, and reversely rotates the drive cam when the operation key is extracted. The lock / unlock detection switch is configured to turn on the second contact when the lock member is engaged with the lock cam. In addition, the second contact portion is turned off when the unlocking means is operated, and the lock member does not move to the engagement position with the lock cam when the operation key is not inserted, and the second contact portion is kept off. A safety circuit is configured by connecting both the first contact portion of the operation key insertion / extraction detection switch portion and the second contact portion of the lock / unlock detection switch portion, and the first and second contact points. The safety circuit is closed when the parts are turned on together.

Depending on whether a configuration, locking fault conditions, and in a state where the locking member has locked the withdrawal of engaging operation key to the locking cam, when the locking and unlocking detection switch unit is withdrawn the operation key without work In addition, the safety cam can be opened by rotating the drive cam with the operation key to turn on the operation key insertion / extraction detection switch. For this reason, fail safe works and safety can be secured.

  Further, the safety switch according to the present invention is the safety switch according to the present invention described above, wherein the lock / unlock detection switch portion operates in a state where the lock member is engaged with the lock cam and locks the operation key. When the operation key is pulled out without being operated, the drive cam is rotated by the operation key to turn off the operation key insertion / extraction detection switch unit to open the safety circuit.

  With this configuration, if the door is forced to open without being unlocked and unlocked, the lock cam, lock member, etc. are destroyed by pulling out the operation key, and the operation key is At the time of slipping, the drive cam rotates in the reverse direction, and the safety circuit can be opened by turning off the operation key insertion / extraction detection switch. For this reason, fail safe works and safety can be secured.

  Further, the safety switch according to the present invention is the above-described safety switch according to the present invention, wherein the drive cam activates the cam operation unit that the operation key collides with and the operation key insertion / removal detection switch unit when the operation key is inserted / removed. The lock cam has a sliding cam portion that slides in contact with the actuating plunger to move the actuating plunger when the drive cam is rotated. A sliding cam portion that holds the lock member in a position where the contact portion of the lock / unlock detection switch portion is turned off, and a lock portion that engages and disengages the lock member; Is.

  With this configuration, when the operation key is inserted / removed, the operation key hits the cam operation unit, the drive cam rotates, the operation plunger is moved, and the operation key insertion / removal detection switch unit is activated. Sometimes, the operation key hits the cam operation section, the lock cam rotates, the lock / unlock detection switch section operates, and the lock member is detachably engaged with the lock section to lock the lock cam. Can do.

  In the safety switch according to the present invention, the cam operation portions of the drive cam and the lock cam have substantially the same shape in the safety switch according to the present invention described above.

  With this configuration, the cam operation portions of the drive cam and the lock cam may have substantially the same shape, so that it is possible to save time and effort for designing the drive cam and the lock cam.

  The safety switch according to the present invention is the safety switch according to the present invention described above, wherein the drive cam and the lock cam are housed in one housing in a state where the drive cam and the lock cam are held by the cam rotation shaft at the respective rotation centers. The switch operation unit is configured.

  With this configuration, the drive cam and the lock cam can be accommodated in one housing, the switch operation unit can be downsized, and the safety switch can be downsized. Here, the housing corresponds to, for example, a head cover.

  The safety switch according to the present invention is the safety switch according to the present invention described above, wherein the lock member moves in the radial direction of the lock cam and engages with the lock portion.

  With this configuration, it is possible to engage the lock member with the lock portion from the radial direction of the lock cam, and it is easy to use when the outer shape of the safety switch is a vertical type.

  The safety switch according to the present invention is the safety switch according to the present invention described above, wherein the lock member moves in a direction perpendicular to the radial direction of the lock cam and engages with the lock portion.

  With this configuration, it is possible to engage the lock member with the lock portion from the side surface direction of the lock cam, and it is easy to use when the outer shape of the safety switch is a horizontal type.

  The safety switch according to the present invention is the above-described safety switch according to the present invention, wherein the failure detection contact portion in the operation key insertion / extraction detection switch portion is a contact portion that is turned on when the operation key is not inserted, and is locked / unlocked. The contact part for failure detection in the detection switch part is a contact part that turns on in the locked state, and the failure detection contact part of the operation key insertion / extraction detection switch part and the failure detection contact part of the lock / unlock detection switch part must be connected. Thus, a failure detection circuit that closes only when the lock function fails is configured, and an LED is incorporated in the failure detection circuit so that the LED is lit when the lock function fails.

  With such a configuration, it is possible to detect that the lock function of the switch body is broken by turning on the LED.

  According to the safety switch of the present invention, the lock / unlock detection switch portion is in a lock function failure state and in a state where the second cam body (lock cam) is locked by the lock means and the operation key is pulled out. When the operation key is pulled out without operating, the operation key insertion / extraction detection switch unit can be operated by rotating the first cam body (drive cam) with the operation key. For this reason, fail safe works and safety can be secured.

  In addition, unlike the conventional safety switch, there is no need to configure a plurality of cam members, plungers, and switch parts, and the configuration is simple, enabling downsizing and cost reduction. As described above, when an extraction load more than a set value is applied to the key in the locked state, it is not necessary to make at least a part of the lock member more fragile than the movable member or the plunger in order to deform and damage the lock member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
A first embodiment of the present invention is shown in FIGS.

  FIG. 1 is a perspective view of Embodiment 1 of a safety switch according to the present invention, and FIG. 2 is a perspective view of the internal structure of the safety switch.

  The safety switch includes a switch operation unit 1 and a switch body 2. As shown in FIG. 1, the switch operation unit 1 includes an operation unit F and a head cover 4 that is a housing that covers the operation unit F. A key insertion slot 5 (6) for inserting an operation key 50 described later is formed in the front surface portion 4a (and the top surface portion 4d) of the head cover 4.

  As shown in FIG. 2, the operation unit F holds the drive cam 10 that is the first cam body, the lock cam 11 that is the second cam body, and the drive cam 10 and the lock cam 11 at the respective rotation centers. The rotating shaft 12 and the actuating plunger 3 are configured. And the operation unit F is accommodated in the head cover 4 which is a housing.

  As shown in FIG. 3, the drive cam 10 is formed with a cam operating portion 17A and a sliding cam portion 17B on the periphery of the cam body 10A. The cam operation portion 17A is formed with recesses 13 and 14 in the peripheral portion of the cam body 10A, and the key engagement portion 15 having a convex shape by the recesses 13 and 14 and the key engagement adjacent to the key engagement portion 15 are formed. The joint portions 16A and 16B are formed.

  In FIG. 3, the left side portion of the key engagement portion 15 is a passive pressure receiving portion 13a, and the right side portion of the key engagement portion 16A is a return pressure receiving portion 13b. Further, the upper side portion of the key engagement portion 16B is a passive pressure receiving portion 14a, and the right side portion of the key engagement portion 15 is a return pressure receiving portion 14b. In this case, the passive pressure receiving portion 13a and the return pressure receiving portion 13b correspond to the operation key 50 inserted from the key insertion port 5, and the passive pressure receiving portion 14a and the return pressure receiving portion 14b are the key. This corresponds to the operation key 50 inserted from the insertion slot 6.

  The sliding cam portion 17B has a cam surface 17a that maximizes the pushing of the operating plunger 3, and a one-side cam surface 17b that minimizes the pushing.

  Further, as shown in FIG. 4, the lock cam 11 is formed with a cam operation portion 22A, a sliding cam portion 22B, and a lock portion 23 on the peripheral portion of the cam main body 11A. The cam operation portion 22A is formed with recesses 18 and 19 in the peripheral portion of the cam body 11A, and the recesses 18 and 19 make a convex key engagement portion 20 and a key engagement adjacent to the key engagement portion 20. The joint portions 21A and 21B are formed.

  In FIG. 4, the left side portion of the key engaging portion 20 is the passive pressure receiving portion 18a, the right side portion of the key engaging portion 21A is the return pressure receiving portion 18b, and the upper side portion of the key engaging portion 21B is It is the passive pressure receiving portion 19a, and the right side portion of the key engaging portion 20 is the return pressure receiving portion 19b. In this case, the passive pressure receiving portion 18a and the return pressure receiving portion 18b correspond to the operation key 50 inserted from the key insertion port 5, and the passive pressure receiving portion 19a and the return pressure receiving portion 19b are the key. This corresponds to the operation key 50 inserted from the insertion slot 6. Therefore, the cam operation portion 17A of the drive cam 10 and the cam operation portion 22A of the lock cam 11 have substantially the same shape.

  The sliding cam portion 22B has a cam surface 22a for holding a lock member 53, which will be described later, at a position where the normally closed contact portion T37 of the lock / unlock detection switch portion 32 is not closed. The lock portion 23 is formed by a notch between the sliding cam portion 22B and the key engagement portion 21B.

  The switch body 2 includes an operation key insertion / extraction detection switch unit 31, a lock / unlock detection switch unit 32, and a lock / unlock detection switch unit 32 as shown in FIG. A coil spring 39 (shown in FIG. 8) which is an internal lock operating means, a lock / unlock operating portion 41 which is an unlock operating means, a rotating lever 44, and a lock member 53 which is a locking means are accommodated. It is configured.

  As shown in FIG. 8, the operation key insertion / extraction detection switch unit 31 includes a switch case 33, and a normally closed contact portion T <b> 34 that is a contact portion is provided in the switch case 33. The normally closed contact portion T34 has a movable contact a1 and a fixed contact b1, and the movable contact a1 is attached to the movable piece 35, and the movable piece 35 is lifted by the spring biasing force of the spring member 36 and is movable. The contact a1 is in contact with the fixed contact b1. A switch side operating rod 37 is provided on the top of the switch case 33 so as to be movable in the vertical direction in FIG. 8, and the switch side operating rod 37 is in contact with the movable piece 35.

  As shown in FIG. 8, the lock / unlock detection switch unit 32 has a switch case 36, and a normally closed contact portion T <b> 37 that is a contact portion is provided in the switch case 36. The normally closed contact portion T37 has a movable contact a2 and a fixed contact b2. The movable contact a2 is attached to a movable piece 38, and the movable piece 38 is a spring of a coil spring (lock actuating means) 39. The movable contact a2 is lifted by the urging force and comes into contact with the fixed contact b2. Further, a switch side operating rod 40 is provided at the bottom of the switch case 36 so as to be movable in the vertical direction in FIG. 8, and the switch side operating rod 40 is in contact with the movable piece 38.

  The unlock actuating portion 41 has an electromagnetic solenoid 42 and a solenoid side actuating rod 43, a switch side actuating rod 40 and a solenoid side actuating rod 43 which move downward in FIG. A rotating lever 44 is provided.

  As shown in FIG. 6, the rotation lever 44 has a rotation shaft portion 45, and the rotation shaft portion 45 is provided with a lever portion 46 and a lever portion 47. A connecting portion 47A is provided. An operation shaft hole 48 is provided at both ends of the rotation shaft portion 45. The operation shaft hole 48 has a cross section of 3/4 circle, and a protrusion 48A is formed inside. The protrusion 48A has two flat surface portions 48a and 48b, and the flat surface portions 48a and 48b are perpendicular to each other.

  Further, as shown in FIG. 7, the bearing member 49 has a disk shape and is provided with an operation shaft 50 having a cross section of ½ circle, and the operation shaft 50 has a flat surface portion 50a. . Further, as shown in FIG. 5, a hexagonal protrusion 49 </ b> A is formed on the front side of the bearing member 49. The bearing member 49 is attached to the rotation shaft portion 45 so that the operation shaft 50 can be rotated by a predetermined angle by inserting the operation shaft 50 into the operation shaft hole 48.

  In the switch case 30 shown in FIG. 1, an operation key insertion / extraction detection switch unit 31 and a lock / unlock detection switch unit 32 are arranged vertically in FIG. In this case, the fixed contact b1 of the normally closed contact portion T34 of the operation key insertion / extraction detection switch portion 31 is connected in series to the fixed contact b2 of the normally closed contact portion T37 of the lock / unlock detection switch portion 32 via the wiring 51. Therefore, a safety circuit R is formed.

  Further, the unlocking operation part 41 is arranged next to the operation key insertion / extraction detection switch part 31 and the lock / unlock detection switch part 32. As shown in FIG. 1, the rotation lever 44 is held by the switch case 30 by rotatably supporting the bearing member 48 in a support hole 30 a provided in the switch case 30. The protrusion 49 </ b> A of the bearing member 49 is exposed on the side surface of the switch case 30. As shown in FIG. 8, the tip portion of the lever portion 46 abuts on the switch side operation rod 40 of the lock / unlock detection switch portion 32, and the lever portion 47 is operated on the solenoid side by the connecting portion 47A. The rod 43 is rotatably connected to the lower end of the rod 43.

  As shown in FIG. 1, a switch operation unit 1 is attached to the switch body 2. In this case, as shown in FIG. 8, the lower end portion of the operation plunger 3 is operated on the switch side of the operation key insertion / extraction detection switch unit 31. The upper end of the actuating plunger 3 is in sliding contact with the cam surface 17 a of the sliding cam portion 17 </ b> B of the driving cam 10.

  Further, the lower end portion of the lock member 53 is connected to the upper end portion of the solenoid operation rod 43 of the unlock operation portion 41, and the upper end portion of the lock member 53 is in sliding contact with the sliding cam portion 22B of the lock cam 10.

  As shown in FIGS. 8 and 10, the upper end portion of the actuating plunger 3 is in sliding contact with the cam surface 17 a of the sliding cam portion 17 </ b> B of the driving cam 10, and the upper end portion of the locking member 53 is the sliding cam portion 22 </ b> B of the locking cam 10. In this operation key extraction state, the coil spring 36 is compressed in the operation key insertion / extraction detection switch unit 31, and the normally closed contact portion T34 is switched off. The movable contact a1 is separated from the fixed contact b1, the coil spring 39 is compressed in the lock / unlock detection switch part 32, and the normally closed contact part T37 is switched off. The movable contact a2 is separated from the fixed contact b2.

  In this operation key pulled out state, the drive cam side passive pressure receiving portion 13a of the drive cam 10 and the lock cam side passive pressure receiving portion 18a of the lock cam 11 are opposed to the key insertion port 8, and the drive cam side passive pressure receiving portion 18a. The pressure receiving portion 13b and the lock cam side passive pressure receiving portion 18b come to face the key insertion port 9.

  As shown in FIG. 1, the operation key 50 has support portions 52 and 53 arranged in parallel with each other on the front side of the plate-like key body 51, and a cam operation is performed between these support portions 52 and 53. This is a configuration in which an insertion opening 55 is formed between the key main body 51 and the cam operation portion 54 while horizontally suspending the portion 54.

  Next, the operation of the safety switch configured as described above will be described.

  When the safety switch having the above configuration is used as a safety switch in a protective fence door (none of which is shown) surrounding the machine tool, an operation key 50 is attached to the door. In this case, the safety circuit R of the safety switch is used for opening and closing the power supply circuit of the machine tool.

  First, in a state where the door is opened, the operation key 50 is pulled out. In this operation key extraction state, as described above, the normally closed contact portion T34 of the operation key insertion / extraction detection switch unit 31 is in a switch-off state.

  Moreover, in the unlocking operation part 41, the electromagnetic solenoid 42 is not excited, and the movement of the solenoid side operating rod 43 is in a free state. The lock member 53 is in sliding contact with the cam surface 22a of the sliding cam portion 22B of the lock cam 11, and the switch side operation rod of the lock / unlock detection switch portion 32 via the solenoid side operation rod 43 and the rotation lever 44. 40 is held in the pushed-in position, and the normally closed contact portion T37 of the lock / unlock detection switch portion 32 is in a switch-off state. Therefore, the machine tool or the like is not driven when the door is open.

  Next, when the door is closed, the operation key 50 is inserted into the key insertion slot 5. As indicated by an arrow in FIG. 10, the operation key 50 of the operation key 50 pushes the passive pressure receiving portion 13 a in the drive cam 10 while the cam operating portion 54 pushes the passive pressure receiving portion 18 a in the lock cam 11. For this purpose, the drive cam 10 and the lock cam 11 are rotated as shown in FIG. 11, and the key engagement portion 16A of the drive cam 10 is inserted into the insertion opening 55 of the operation key 50 as shown in FIG. The key engagement portion 21A of the lock cam 11 is engaged.

  By the rotation of the drive cam 10, the actuation plunger 3 slides on the one-side cam 17 b of the slide cam portion 17 of the drive cam 10 to reduce the pushing force. For this reason, in the operation key insertion / extraction detection switch part 31, the switch side operating rod 37 is lifted by the restoring force of the coil spring 36, and as shown in FIG. 11, the normally closed contact part T34 of the operation key insertion / extraction detection switch part 31. Is switched on.

  At the same time, due to the rotation of the lock cam 11, the upper end portion of the lock member 53 reaches the lock portion 23 from the sliding cam portion 22 </ b> B of the lock cam 11. For this reason, in the lock / unlock detection switch section 32, the switch side operating rod 40 is pushed down by the restoring force of the coil spring 39, and the rotating lever 44 rotates counterclockwise in FIG. The operating rod 43 is lifted and the lock member 53 enters the lock portion 23. Then, as shown in FIG. 11, the normally closed contact portion T37 of the lock / unlock detection switch portion 32 is switched on.

  As described above, in the operation key insertion / extraction detection switch unit 31 and the lock / unlock detection switch unit 32, both the normally closed contact portions T34 and T37 are turned on, and the power supply circuit of the machine tool or the like is turned on. The machine is ready for driving and the safety circuit R functions.

  Next, when releasing the lock, as shown in FIG. 12, the electromagnetic solenoid 42 is excited to move the solenoid-side operating rod 43 downward in FIG. The engagement with the lock part 23 is released. At the same time, the pivot lever 44 pivots clockwise in FIG. 12 to push the switch side operating rod 40 against the spring biasing force of the coil spring 39, and the lock / unlock detection switch section 32 is normally closed. The contact portion T37 is switched off. When the normally closed contact portion T37 is switched off, the power supply circuit of the machine tool or the like is turned off and the drive of the machine tool is stopped.

  Then, by pulling out the operation key 50 from the switch operation unit 1 by opening the door, the drive cam 10 and the lock cam 11 are pulled down by the cam operation unit 54, and the drive cam 10 and the lock cam 11 are rotated in the reverse direction. The operation key is pulled out as shown in FIG. Then, in the lock / unlock operation unit 41, the excitation of the electromagnetic solenoid 42 is released.

  Further, if the door is forcibly opened without being unlocked in the locked state, the operation key 50 is pulled out, so that the cam operating portion 54 of the operation key 50 in the lock cam 11 as shown in FIG. As a result, the key engaging portion 21A is destroyed and the operation key 50 slips through. When the operation key 50 passes through, the cam operating portion 54 pulls the drive cam 10 down to rotate the drive cam 10 in the reverse direction.

  Due to the reverse rotation of the drive cam 10, the actuating plunger 3 is pushed in, the switch side actuating rod 37 of the operation key insertion / extraction detection switch part 31 is pushed in, and the normally closed contact part T34 of the operation key insertion / extraction detection switch part 31 is switched off. It becomes a state. For this reason, the safety circuit R is opened, the power supply circuit is turned off, and the drive of the machine tool is stopped.

  The operation of the safety switch described above is when the operation key 50 is inserted into the key insertion slot 5 as shown in FIG. 1, but when the operation key 50 is inserted into the key insertion slot 6, FIG. Through the operation shown in FIG. That is, in the operation key 50, the cam operating portion 54 presses the passive pressure receiving portion 14 a in the drive cam 10, and the cam operating portion 54 presses the passive pressure receiving portion 19 a in the lock cam 11.

  Therefore, the drive cam 10 and the lock cam 11 are rotated as shown in FIG. 15, and the key engagement portion 15 of the drive cam 10 and the key engagement portion of the lock cam 11 are inserted into the insertion opening 55 of the operation key 50. 20 engages.

  As shown in FIG. 15, the normally closed contact portion T <b> 34 of the operation key insertion / extraction detection switch portion 31 is switched on in the same manner as when the operation key 50 is inserted into the key insertion slot 5 by the rotation of the drive cam 10. It becomes the state of. Further, the lock member 53 enters the lock portion 23 of the lock cam 11 in the same manner as when the operation key 50 is inserted into the key insertion slot 5 by the rotation of the lock cam 11. Then, as shown in FIG. 15, the normally closed contact portion T37 of the lock / unlock detection switch portion 32 is switched on.

  Thus, in the operation key insertion / extraction detection switch unit 31 and the lock / unlock detection switch unit 32, the normally closed contact portions T34 and T37 are turned on together with the power supply circuit of the machine tool or the like being turned on. The machine tool is ready for driving and the safety circuit R functions.

  Next, when releasing the lock, as shown in FIG. 16, by energizing the electromagnetic solenoid 42, the lock / unlock operation is performed in the same manner as when the operation key 50 is inserted into the key insertion slot 5. In the lock detection switch part 32, the normally closed contact part T37 is switched off. When the normally closed contact portion T37 is switched off, the power supply circuit of the machine tool or the like is turned off and the drive of the machine tool is stopped.

  Then, by pulling out the operation key 50 from the switch operation unit 1 by opening the door, the drive cam 10 and the lock cam 11 are pulled down by the cam operation unit 54 and the drive cam 10 and the lock cam 11 are rotated in the reverse direction. Due to the reverse rotation of the drive cam 10, the normally closed contact portion T34 of the operation key insertion / extraction detection switch portion 31 is switched off in the same manner as when the operation key 50 is inserted into the key insertion slot 5. The normally closed contact portion T37 of the lock / unlock detection switch portion 32 is switched off.

  Further, if the door is forcibly opened without being unlocked in the locked state, the operation key 50 is pulled out, so that the cam operating portion 54 of the operation key 50 in the lock cam 11 as shown in FIG. As a result, the key engaging portion 20 is destroyed and the operation key 50 slips through. When the operation key 50 slips through, the cam operating portion 54 pulls down the drive cam 10 to rotate the drive cam 10 in the reverse direction.

  Due to the reverse rotation of the drive cam 10, the actuating plunger 3 is pushed in, the switch side actuating rod 37 of the operation key insertion / extraction detection switch part 31 is pushed in, and the normally closed contact part T34 of the operation key insertion / extraction detection switch part 31 is switched off. It becomes a state. For this reason, the safety circuit R is opened and the power supply circuit is turned off, so that the driving of the machine tool is stopped.

  In the above-described locked state, as shown in FIG. 18, the rotation shaft portion 45 of the rotation lever 44 has the flat surface portion 48 a of the protruding portion 48 </ b> A of the operation shaft hole 48, and the operation shaft 50 of the bearing member 49. In the state of facing the flat surface portion 50a in parallel, and in the unlocked state described above, the rotation shaft portion 45 of the rotation lever 44 is in the flat surface portion 48a of the operation shaft hole 48 as shown in FIG. Is inclined with respect to the flat surface portion 50 a of the operation shaft 50 of the bearing member 49.

  When the lock is manually released, the bearing member 49 is manually rotated using the hexagonal protrusion 49A of the bearing member 49 as shown in FIG. In this case, the rotation of the bearing member 49 causes the flat surface portion 50a of the operation shaft 50 to abut against the flat surface portion 48a of the operation shaft hole 48, and the movable shaft portion 45 is rotated in the clockwise direction in FIG. The lever 44 is rotated and the solenoid-side operation rod 43 is moved downward in FIGS. 12 and 16 to release the engagement of the lock member 53 with the lock portion 23 of the lock cam 11.

  At the same time, the switch-side actuating rod 40 is lifted against the spring biasing force of the coil spring 39 by the clockwise rotation of the rotation lever 44, and the normally closed contact portion T37 is switched off in the lock / unlock detection switch portion 32. It becomes the state of. When the normally closed contact portion T37 is switched off, the power supply circuit of the machine tool or the like is turned off and the drive of the machine tool is stopped.

  As described above, according to the first embodiment of the present invention, in the lock function failure state, and in a state where the lock member 53 is engaged with the lock portion 23 of the lock cam 11 and the pull-out of the operation key 50 is locked. When the operation key 50 is pulled out without operating the lock / unlock detection switch unit 32, the drive cam 10 is rotated by the operation key 50 to operate the operation key insertion / extraction detection switch unit 31 and the safety circuit R is activated. Can be opened. For this reason, fail safe works and safety can be secured.

  In addition, unlike the conventional safety switch, there is no need to configure a plurality of cam members, plungers, and switch parts, and the configuration is simple, enabling downsizing and cost reduction. As described above, when an extraction load more than a set value is applied to the key in the locked state, it is not necessary to make at least a part of the lock member more fragile than the movable member or the plunger in order to deform and damage the lock member.

  Further, according to the first embodiment of the present invention, the drive cam 10 operates to operate the cam operation unit 17A with which the operation key 50 abuts and the operation key insertion / extraction detection switch unit 31 when the operation key 50 is inserted / removed. The lock cam 11 has a sliding cam portion 17B that moves the operating plunger 3 when the plunger 3 is in sliding contact with the rotation, and the lock cam 11 is connected to the cam operation portion 22A with which the operation key 50 abuts when the operation key 50 is inserted or removed. By having the sliding cam portion 22B in which the lock member 53 is slidably contacted and the lock portion 23 in which the lock member 53 is detachably engaged, when the operation key 50 is inserted / removed, the operation key 50 can operate the cam. The drive cam 11 rotates against the portion 17A and moves the operating plunger 3 to operate the operation key insertion / extraction detection switch portion 31. When the operation key 50 is inserted / removed, the operation key 50 is The lock cam 11 is rotated by abutting against the working portion 22A, the lock / unlock detection switch portion 32 is operated, and the lock member 53 is detachably engaged with the lock portion 23 to lock the lock cam 11. it can.

  Further, according to the first embodiment of the present invention, the cam operation portions 17A and 22A of the drive cam 10 and the lock cam 11 may have substantially the same shape, so that the design effort of the drive cam 10 and the lock cam 11 is omitted. In addition, the drive cam 10 and the lock cam 11 can be accommodated in one head cover 4, the switch operation unit 1 can be downsized, and the safety switch can be downsized.

  Further, according to the first embodiment of the present invention, the lock member 53 moves in the radial direction of the lock cam 11 and engages with the lock portion 23, and is used when the outer shape of the safety switch is vertical. It becomes easy.

  In the first embodiment of the present invention described above, a case has been disclosed in which the lock cam 10 has been broken as the lock breakage of the key engagement portion 21A (key engagement portion 20) of the lock cam 10. Is generated even if the lock member 53 or the operation key 50 is deformed or damaged. In the safety switch according to the present invention, the lock breakage is not limited to the breakage of the lock cam 10.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS. In this case, the same parts and portions as those of the first embodiment of the present invention described above are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment of the present invention described above, the lock / unlock detection switch unit 32 is arranged side by side next to the operation key insertion / extraction detection switch unit 31, but in the second embodiment of the present invention, the lock / unlock detection switch unit 32 is locked. The unlock detection switch unit 32 is turned sideways, the electromagnetic solenoid 42 is turned sideways, and the lock member 53 is held sideways by the switch case 30 and connected to the solenoid-side actuating rod 43. Yes. A switch operating arm 60 is fixed to the lock member 53, and the switch operating arm 60 abuts on the switch side operating rod 40 of the lock / unlock detection switch unit 32. Therefore, the rotation lever 44 is not used.

  First, when the door is opened, the operation key 50 is pulled out as shown in FIG. In this state, in the switch operation unit 1, the operation plunger 3 is in sliding contact with the cam surface 17 a of the drive cam 10, and the switch side operation rod 37 of the operation key insertion / extraction detection switch unit 31 is pushed through the operation plunger 3. The normally closed contact portion T34 of the operation key insertion / extraction detection switch portion 31 is in a switch-off state.

  Moreover, in the unlocking operation part 41, the electromagnetic solenoid 42 is not excited, and the movement of the solenoid side operating rod 43 is in a free state. The lock member 53 is in sliding contact with the side surface 22b of the sliding cam portion 22B of the lock cam 11. In the lock / unlock detection switch portion 32, the switch-side operation rod 40 is operated by the switch provided on the lock member 53. The coil spring 39 is compressed by being pushed by the arm 60, the normally closed contact portion T37 is switched off, and the movable contact a2 is separated from the fixed contact b2. Therefore, the machine tool or the like is not driven when the door is open.

  Next, when the door is closed, the operation key 50 rotates the drive cam 10 and the lock cam 11 as in the case of the first embodiment of the present invention described above. Then, as the driving cam 10 rotates, the operating plunger 3 slides on the one-side cam surface 17b of the sliding cam portion 17A of the driving cam 10 to reduce the pushing force. For this reason, in the operation key insertion / extraction detection switch part 31, the switch side operating rod 37 is lifted by the restoring force of the coil spring 36, and as shown in FIG. 22, the normally closed contact part T34 of the operation key insertion / extraction detection switch part 31 is lifted. Is switched on.

  At the same time, due to the rotation of the lock cam 11, the distal end portion of the lock member 53 reaches the lock portion 23 from the side surface 22 b of the sliding cam portion 22 B of the lock cam 11. For this purpose, in the lock / unlock detection switch section 32, the switch-side operating rod 40 protrudes by the return force of the coil spring 39, pushes the lock member 53 via the switch operating arm 60, and the end of the lock member 53 Is inserted into the lock portion 23 of the lock cam 11. Then, as shown in FIG. 22, the normally closed contact portion T37 of the lock / unlock detection switch portion 32 is switched on.

  As described above, in the operation key insertion / extraction detection switch portion 31 and the lock / unlock detection switch portion 32, the normally closed contact portions T34 and T37 are turned on, the power supply circuit of the machine tool or the like is turned on, and the machine tool is turned on. Becomes a drivable state, and the safety circuit R functions.

  Next, when releasing the lock, the solenoid-side actuating rod 43 is moved to the right in FIG. 21 by exciting the electromagnetic solenoid 42 to engage the lock member 53 with the lock portion 23 of the lock cam 11. Is released. At the same time, the switch-side operating rod 40 is moved rightward against the spring biasing force of the coil spring 39, and the normally closed contact T37 is switched off in the lock / unlock detection switch 32. When the normally closed contact portion T37 is switched off, the power supply circuit of the machine tool or the like is turned off and the drive of the machine tool is stopped.

  Then, by pulling out the operation key 50 from the switch operation unit 1 by opening the door, the drive cam 10 and the lock cam 11 are pulled down by the cam operation unit 54 and the drive cam 10 and the lock cam 11 are rotated in the reverse direction.

  The actuating plunger 3 is pushed in by reverse rotation of the drive cam 10, the switch side actuating rod 37 of the operation key insertion / extraction detection switch part 31 is pushed in, and the normally closed contact part T34 of the operation key insertion / extraction detection switch part 31 is switched off. become.

  Further, if the door is forcibly opened without being unlocked in the locked state, the operation key 50 is pulled out, so that the cam operating portion 54 of the operation key 50 in the lock cam 11 as shown in FIG. As a result, the key engaging portion 21A is destroyed and the operation key 50 slips through. When the operation key 50 slips through, the cam operating portion 54 pulls down the drive cam 10 to rotate the drive cam 10 in the reverse direction.

  Due to the reverse rotation of the drive cam 10, the actuating plunger 3 is pushed in, the switch side actuating rod 37 of the operation key insertion / extraction detection switch part 31 is pushed in, and the normally closed contact part T34 of the operation key insertion / extraction detection switch part 31 is switched off. It becomes a state. For this reason, the safety circuit R is opened and the power supply circuit is turned off, so that the driving of the machine tool is stopped.

  As described above, in the second embodiment of the present invention, the lock member 53 moves in the direction perpendicular to the radial direction of the lock cam 11 and engages with the lock portion 23, so that the outer shape of the safety switch It becomes easy to use when is horizontal.

(Embodiment 3)
A third embodiment of the present invention will be described with reference to FIGS. In the third embodiment of the present invention, a failure detection circuit S is added to the first embodiment of the present invention described above. In this case, the same parts and portions as those of the first embodiment of the present invention are denoted by the same reference numerals and description thereof is omitted, and each of the operation key 50 in the pulled-out state, the locked state, the unlocked state, and the locked failure state is provided. Since this operation is the same as that in the first embodiment of the present invention described above, the description thereof is omitted.

  In the third embodiment of the present invention, the operation key insertion / extraction detection switch unit 31 includes the normally closed contact portion T34 and the switching operation of the normally closed contact portion T34 in addition to the normally closed contact portion T34. A failure detection normally open contact portion T70, which is a contact portion for failure detection that performs the reverse switching operation, is provided, and the lock / unlock detection switch portion 32 includes this normally closed contact portion T37 as well as this normally closed contact portion T37. In conjunction with the closed contact portion T37, a failure detection normally closed contact portion T71, which is a failure detection contact portion that performs the same switching operation as the switching operation of the normally closed contact portion T34, is provided. The failure detection normally open contact portion T70 has a movable contact a3 and a fixed contact b3, and the failure detection normally closed contact portion T71 has a movable contact a4 and a fixed contact b4.

  In addition to the safety circuit R, a failure detection circuit S is configured. In this failure detection circuit S, the fixed contact b3 of the failure detection normally open contact portion T70 is connected to one terminal portion 73a of the LED 73 via the wiring 72, and the other terminal portion 73b of the LED 73 is failed via the wiring 74. It is comprised by the serial connection connected to the stationary contact b4 of the normally closed contact part T71 for a detection.

  Therefore, in the pulled-out state of the operation key 60, as shown in FIG. 23, in the operation key insertion / extraction detection switch unit 31, the movable contact a3 of the failure detection normally-open contact portion T70 is in contact with the fixed contact b3. In the unlock detection switch 32, the failure detection circuit S does not operate because the movable contact a4 of the failure detection normally closed contact portion T71 is separated from the fixed contact b4 and is in a normal state.

  In the locked state, as shown in FIG. 24, in the operation key insertion / extraction detection switch unit 31, the movable contact a3 of the failure detection normally open contact portion T70 is separated from the fixed contact b3. In the switch part 32, the failure detection circuit S does not operate because the movable contact a4 of the failure detection normally closed contact part T71 is in contact with the fixed contact b4 and is in a normal state.

  In the unlocked state, as shown in FIG. 25, in the operation key insertion / extraction detection switch unit 31, the movable contact a3 of the failure detection normally open contact portion T70 is separated from the fixed contact b3, and the lock / unlock detection switch unit. At 32, the failure detection circuit S does not operate because the movable contact a4 of the failure detection normally closed contact portion T71 is separated from the fixed contact b4 and is in a normal state.

  In the lock failure state, as shown in FIG. 26, in the operation key insertion / extraction detection switch unit 31, the movable contact a3 of the failure detection normally open contact portion T70 contacts the fixed contact b3, and the lock / unlock detection switch unit. In 32, when the movable contact a4 of the normally closed contact portion T71 for failure detection comes into contact with the fixed contact b4, the failure detection circuit S is energized, and the LED 73 is turned on to detect the failure.

  According to the third embodiment of the present invention described above, the operation key insertion / extraction detection switch unit 31 has the failure detection normally open contact portion 70, and the lock / unlock detection switch portion 32 has the failure detection normally closed contact. A failure detection circuit S is configured by connecting the failure detection normally open contact portion 70 and the failure detection normally closed contact portion 71, and an LED 73 is incorporated in the failure detection circuit S. Since the LED 73 is turned on when the lock function is broken, it can be detected by turning on the LED 73 that the lock function of the safety switch is broken.

  According to the safety switch of the present invention, fail-safe functions, safety can be ensured, the configuration is simple, and miniaturization and cost reduction are possible. When the extraction load exceeding the set value is applied, the lock member does not necessarily need to be deformed and damaged, which is useful for a safety switch used for a door lock switch or the like.

It is a perspective view of Embodiment 1 of the safety switch concerning the present invention. It is a perspective view of the internal structure of the safety switch. It is a side view of a drive cam. It is a side view of a lock cam. It is a perspective view in the state where a bearing member was attached to a rotation lever. It is a perspective view of a rotation lever. It is a perspective view of a bearing member. It is composition explanatory drawing of the internal structure of the safety switch. It is operation | movement explanatory drawing of the locked state in the safety switch. In Embodiment 1 of the safety switch which concerns on this invention, it is operation | movement explanatory drawing of the operation key pulling-out state in case the operation key is inserted in the key insertion slot beside a switch operation part. It is operation | movement explanatory drawing of the locked state in the safety switch. It is operation | movement explanatory drawing of the lock release state in the safety switch. It is operation | movement explanatory drawing of the lock failure state in the safety switch. In Embodiment 1 of the safety switch which concerns on this invention, it is operation | movement explanatory drawing of the operation key pulling-out state in case the operation key is inserted in the key insertion slot in the top part of a switch operation part. It is operation | movement explanatory drawing of the locked state in the safety switch. It is operation | movement explanatory drawing of the lock release state in the safety switch. It is operation | movement explanatory drawing of the lock failure state in the safety switch. It is explanatory drawing of the relationship between the movable lever and bearing member in a locked state. It is explanatory drawing of the relationship between the movable lever and bearing member in an unlocked state. It is explanatory drawing of the relationship between a movable lever and a bearing member in the case of performing unlocking manually. It is structure explanatory drawing of the internal structure of the operation key pull-out state in Embodiment 2 of the safety switch which concerns on this invention. It is composition explanatory drawing of the internal structure of the locked state in the safety switch. In Embodiment 3 of the safety switch which concerns on this invention, it is operation | movement explanatory drawing of the safety circuit and failure detection circuit in the operation key pulling-out state. It is operation | movement explanatory drawing of the safety circuit and failure detection circuit in the locked state in the safety switch. It is operation | movement explanatory drawing of the safety circuit and failure detection circuit in the lock release state in the safety switch. It is operation | movement explanatory drawing of the safety circuit and failure detection circuit in the lock failure state in the safety switch.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Switch operation part 2 Switch body 3 Actuator plunger 4 Head cover (housing)
5 Key insertion slot 6 Key insertion slot 10 Drive cam (first cam body)
11 Lock cam (second cam body)
12 Rotating shaft 13a Passive pressure receiving portion 13b Return pressure receiving portion 14a Passive pressure receiving portion 14b Return pressure receiving portion 15 Key engaging portion 16A, 16B Key engaging portion 17A Cam operating portion 17B Sliding cam portion 17a Cam surface 17b One side cam Surface 18a Passive pressure receiving portion 18b Return pressure receiving portion 19a Passive pressure receiving portion 19b Return pressure receiving portion 20 Key engagement portion 21A, 21B Key engagement portion 22A Cam operation portion 22B Sliding cam portion 22b Side surface 23 Lock portion 31 Operation key Insertion / extraction detection switch section 32 Lock / unlock detection switch section 37 Switch side operation rod 39 Coil spring (lock operation means)
40 Switch side actuating rod 41 Unlock actuating part (unlock actuating means)
42 Electromagnetic Solenoid 43 Solenoid Acting Rod 44 Rotating Lever 50 Operation Key 53 Lock Member (Locking Means)
73 LED
F Operation unit R Safety circuit S Failure detection circuit T34 Normally closed contact (contact)
T37 Normally closed contact (contact)
T70 Failure detection normally open contact (failure detection contact)
T71 Failure detection normally closed contact (failure detection contact)

Claims (9)

A safety switch having a switch operation unit for operating the switch unit, and operating the switch unit by inserting and removing an operation key in the switch operation unit to open and close a safety circuit;
The switch operation unit has first and second cam bodies that rotate by inserting and removing one of the operation keys, and the switch unit is turned on and off by rotation of the first cam body, An operation key insertion / extraction detection switch for detecting insertion / extraction, a lock means for locking the second cam body when the operation key is inserted, a lock operation means for operating the lock means, and an operation of the lock operation means Unlock actuating means for releasing the lock, and a lock / unlock detecting switch part for detecting the locked / unlocked state of the second cam body by the on / off actuating operation of the lock actuating means and the unlock actuating means. In addition, the operation key insertion / extraction detection switch part has a first contact part that is turned on to insert the operation key. The lock / unlock detection switch unit has a failure detection contact unit in addition to the second contact unit that is turned on when the lock member is operated, When the operation key insertion / extraction detection switch part operates and the lock / unlock detection switch part does not operate when the key is pulled out, it is detected by turning on / off both of the failure detection contact parts. A safety switch characterized by detecting that the lock function is broken.   The first cam body is a drive cam, the second cam body is a lock cam, the lock means is a lock member, and the lock operation means operates the lock member to move the lock member. It is configured to lock the rotation of the lock cam by engaging with the lock cam when the operation key is inserted, and the unlock operation means is configured to release the lock by the lock member when the lock operation means is operated. The operation key insertion / extraction detection switch unit rotates the drive cam when the operation key is inserted to turn on the first contact portion, and reversely rotates the drive cam when the operation key is extracted. The first contact portion is configured to be turned off, and the lock / unlock detection switch portion is configured to move the second contact portion when the lock member is engaged with the lock cam. The point member is turned on, and the second contact portion is turned off when the unlocking means is operated, and the lock member does not move to the engagement position with the lock cam when the operation key is not inserted. The second contact portion is kept in an OFF state, and both the first contact portion of the operation key insertion / extraction detection switch portion and the second contact portion of the lock / unlock detection switch portion are connected. The safety switch according to claim 1, wherein the safety circuit is configured so that the safety circuit is closed when the first and second contact portions are both turned on.   When the lock member is engaged with the lock cam and the operation key is locked and the operation key is pulled out without operating the lock / unlock detection switch, the operation key is The safety switch according to claim 2, wherein the safety circuit is opened by rotating the drive cam to turn off the operation key insertion / extraction detection switch. The drive cam is configured such that when the operation key is inserted / removed, a cam operation unit that the operation key collides with and an operation plunger that operates the operation key insertion / removal detection switch unit are in sliding contact with each other to rotate the operation cam The lock cam includes a cam operation unit that the operation key abuts with the cam operation unit when the operation key is inserted and removed, and the lock member is in sliding contact with the lock member. 3. A slide cam portion that holds the contact portion of the unlock detection switch portion at a position where the unlock portion is turned off, and a lock portion that engages and disengages the lock member. Or the safety switch of Claim 3 . The safety switch according to claim 4 , wherein the cam operation portions of the drive cam and the lock cam have substantially the same shape. 3. The drive cam and the lock cam are housed in one housing in a state of being held by a cam rotation shaft at their respective rotation centers to constitute the switch operation unit. The safety switch according to claim 5 . The safety switch according to any one of claims 2 to 6 , wherein the lock member moves in a radial direction of the lock cam and engages with the lock portion. The locking member, the safety switch according to any one of claims 2 to 6, characterized in that to engage the locking portion to move in a direction perpendicular to the radial direction of the lock cam.   The failure detection contact portion in the operation key insertion / extraction detection switch portion is a contact portion that is turned on when the operation key is not inserted, and the failure detection contact portion in the lock / unlock detection switch portion is turned on in the locked state. A contact portion that performs the closing operation only when the lock function fails by connecting the failure detection contact portion of the operation key insertion / extraction detection switch portion and the failure detection contact portion of the lock / unlock detection switch portion. The safety switch according to claim 1, wherein a failure detection circuit is configured, an LED is incorporated in the failure detection circuit, and the LED is turned on when the lock function fails.

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