Safety device of machine tool

Abstract

To provide a safety device of a machine tool which prevents occurrence of a free hand.SOLUTION: A drilling machine 10 which is a machine tool includes: a spindle 12 configured to be operated by drive force of a spindle motor 13 to perform processing to a workpiece; a spindle lifting lever 14 configured to be operable by one hand of a user to operate the spindle 12; a touch sensor 17 configured so that the user may touch it with the other hand; and a control device 18 which controls operation of the spindle motor 13. A safety device 20 stops the operation of the spindle motor 13 when it is determined that the other hand of the user is not in contact with the touch sensor 17.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a safety device for a machine tool.

Background Art

[0002] Conventionally, a machine tool equipped with an operating member for manual operation by a user is known. For example, Patent Document 1 discloses a lathe including a main switch, a switch for a spindle / feed motor, a spindle, and a spindle lifting lever. The lathe disclosed in Patent Document 1 is configured such that the spindle rotates when the main switch is turned on and the switch for the spindle / feed motor is turned on. Then, the user can machine a workpiece by operating the spindle lifting lever, which is an operating member, to lower the spindle.

[0003] Such a lathe is configured to be operated with one hand (right hand) on the spindle lifting lever. In such a configuration, for example, when the user operates the spindle lifting lever with one hand, the other hand (left hand) becomes a free hand. For this reason, there is a risk that the free hand may touch the spindle, a tool attached to the spindle, or a workpiece during machining.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] (Problems to be Solved by the Invention) In view of the above circumstances, one object of the present invention is to provide a safety device for a machine tool in which a free hand does not occur during operation (which can also be during machining).

[0006] (Means for Solving the Problems) The safety device for a machine tool according to the present invention is An operating unit that operates by the driving force of a driving power source and performs processing on a workpiece, A first operating member that is operated by one hand of a user when operating the processing unit, A safety device for a machine tool comprising: A contact sensor that detects contact of the other hand of the user, A control device that controls the operation of the processing unit by the driving power source, Comprising: The control device is configured to stop the operation of the processing unit by the driving power source when the other hand of the user is in a non-contact state with the contact sensor.

[0007] According to the present invention, when the other hand of the user is in a non-contact state where it is not touching the contact sensor, the operation by the driving power source of the processing unit stops. For this reason, in order for the user to operate the first operating member with one hand (right hand) to perform processing on the workpiece, the other hand (left hand) must be kept in contact with the contact sensor. Therefore, it is possible to provide a machine tool in which a free hand does not occur.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described. In the following description, the "safety device for a machine tool" may be abbreviated as the "safety device". Further, in the present embodiment, a ball screw machine is shown as an example of a machine tool to which the safety device is applied.

[0010] <Configuration of Ball Screw Machine> FIG. 1 is a diagram showing a configuration example of a ball screw machine 10 to which the safety device according to the present embodiment is applied. FIG. 2 is a block diagram showing a configuration example of the ball screw machine 10 to which the safety device according to the present embodiment is applied. As shown in FIG. 1, the ball screw machine 10 includes a spindle 12 provided on a spindle head 11 (spindle head), a spindle motor 13, a spindle lifting lever 14, and a start lever 15. Further, as shown in FIG. 2, the ball screw machine 10 includes a start switch 16, a touch sensor 17, and a control device 18. And the safety device 20 includes the control device 18 and the touch sensor 17.

[0011] The spindle 12 is an example of the processing part of the present invention, and the spindle motor 13 is an example of the driving power source of the present invention. The spindle 12 is configured to rotate by the driving force of the spindle motor 13. Further, the spindle 12 includes a tool chuck 121 and is configured to be detachable from a tool (such as a drill). Further, the spindle 12 is associated with the spindle lifting lever 14 and is configured to be movable substantially in the vertical direction with respect to the spindle head 11 in response to an operation of the spindle lifting lever 14 by the user. The spindle motor 13 is a driving power source for the spindle 12, and an electric motor capable of rotating in both forward and reverse directions is applied. Note that the configurations of the spindle 12 and the spindle motor 13 are not particularly limited, and known configurations can be applied.

[0012] The spindle lifting lever 14 is an operation member that can be manually operated by the user with one hand (right hand), and is an example of the first operation member of the present invention. The spindle lifting lever 14 is provided on the right side surface of the spindle head 11 so as to be rotatable (or swingable in the vertical direction like a pendulum) with respect to the spindle head 11 when viewed from the user of the ball screw machine 10 (the user facing the ball screw machine 10). The spindle lifting lever 14 is associated with the spindle 12 as described above. The configuration of the spindle lifting lever 14 is not particularly limited, and a conventionally known configuration can be applied.

[0013] The start lever 15 is an operating member that can be manually operated by the user with the other hand (left hand), and is an example of the second operating member of the present invention. The start lever 15 is an operating member for switching the stop, forward rotation, and reverse rotation of the main shaft motor 13. The start lever 15 is provided at the left end portion of the main shaft head 11 or in the vicinity thereof (at least on the left side of the main shaft lifting lever 14 as viewed from the user of the ball disk 10). Further, the start lever 15 is provided so as to be rotatable within a predetermined angular range with respect to the main shaft head 11. And the start lever 15 can be moved to an OFF position which is a position in the middle of the rotatable range, a forward rotation position which is a position at one end of the rotatable range, and a reverse rotation position which is a position at the other end of the rotatable range by rotating with respect to the main shaft head 11. In the present embodiment, the start lever 15 is provided so as to be rotatable about a vertical axis with respect to the main shaft head 11.

[0014] The start switch 16 is a switch for detecting the position of the start lever 15. For example, an ON-OFF-ON switch (3-position switch) is applied to the start switch 16. In this case, the start switch 16 is configured to be in the OFF position when the start lever 15 is in the OFF position, in one ON position when the start lever 15 is in the forward rotation position, and in the other ON position when the start lever 15 is in the reverse rotation position.

[0015] The touch sensor 17 is an example of the contact sensor of the present invention. The touch sensor 17 is provided on the start lever 15. The touch sensor 17 is a sensor for detecting whether or not the user is touching the start lever 15. A capacitance type touch sensor is applied to the touch sensor 17. The configuration of the touch sensor 17 will be described later.

[0016] The control device 18 (sometimes referred to as a control panel) is a device that controls the ball board 10. The control device 18 is configured to be able to detect the position of the start switch 16 and acquire the capacitance of the touch sensor 17 (specifically, the total capacitance generated between the touch sensor 17 and an object in contact with the touch sensor 17). Further, the control device 18 is configured to control (drive) the spindle motor 13. In other words, the control device 18 is configured to control the operation (rotation) of the spindle 12 by the driving force of the spindle motor 13. The control device 18 includes a computer having a CPU, a ROM, and a RAM. A computer program for controlling the ball board 10 is stored in advance in the ROM of the computer. The CPU of the computer reads out this computer program from the ROM, expands it in the RAM, and executes it. Thereby, the control of the ball board 10 (the operations described later) is realized.

[0017] FIGS. 3A and 3B are diagrams showing the configurations of the start lever 15 and the touch sensor 17. Note that FIG. 3A is an external view of the start lever 15, and FIG. 3B is an exploded view of the start lever 15. As shown in FIGS. 3A and 3B, the start lever 15 includes a base end portion 151, a grip portion 152, and the touch sensor 17. The base end portion 151 is a portion that is rotatably supported with respect to the spindle head 11. The grip portion 152 has a shape and dimensions that can be gripped by a user with one hand (the left hand in this embodiment). In this embodiment, the grip portion 152 has a round bar shape. Further, the grip portion 152 is formed of an electrically insulating material such as a resin material.

[0018] The touch sensor 17 includes a sensor body 171, a plurality of electrodes 172, and a plate 173 that electrically connects (conducts) the sensor body 171 and the plurality of electrodes 172. The touch sensor 17 is configured such that when an object contacts at least one of the plurality of electrodes 172, the total capacitance generated between the plurality of electrodes 172 and the object changes. It can also be said that the touch sensor 17 is configured to be able to output a signal indicating the total capacitance to the control device 18. The plurality of electrodes 172 are arranged such that at least a part thereof is exposed on the outer peripheral surface of the grip portion 152 so that the hand (left hand) of the user who grips the grip portion 152 makes direct contact. In the present embodiment, the plurality of electrodes 172 are rod-shaped members formed of a conductive material. The plate 173 is a plate-shaped member formed of a conductive material. FIGS. 3A and 3B show an example in which the plurality of electrodes 172 are square rod-shaped members. The plurality of electrodes 172 are arranged such that their longitudinal directions are substantially parallel to the longitudinal direction of the grip portion 152 and are arranged at substantially equal intervals in the circumferential direction on the outer periphery of the grip portion 152. Specifically, on the outer peripheral surface of the grip portion 152, a plurality of grooves 153 having a cross-sectional shape corresponding to the dimensions and shape of the electrode 172 and extending in the longitudinal direction are provided at substantially equal intervals in the circumferential direction. Each of the plurality of electrodes 172 is accommodated in each of the plurality of grooves 153. As a result, a part of the outer peripheral surface of each of the plurality of electrodes 172 is exposed on the outer peripheral surface of the grip portion 152.

[0019] Note that the configurations and arrangements of the plurality of electrodes 172 and the plate 173 are not limited to the above configurations and arrangements. The main point is that the plurality of electrodes 172 may be configured and arranged such that when the user grips the grip portion 152 with the other hand (left hand), the other hand of the user makes direct contact with at least one of the electrodes 172. The plate 173 may electrically connect the plurality of electrodes 172 and the sensor body 171.

[0020] <Operation of the ball board and the safety device> Next, the operations of the pachinko machine 10 and the safety device 20 will be described. When the hand of an operator comes into direct contact with at least one of the plurality of electrodes 172 of the touch sensor 17, a capacitance is generated between the electrode 172 touched by the hand of the operator and the hand of the operator. The control device 18 acquires the total capacitance generated between the plurality of electrodes 172 and the hand of the operator from the touch sensor 17. When the acquired total capacitance is less than a preset threshold value, the control device 18 determines that the contact condition, which is a condition indicating that the hand of the user is touching, is not satisfied (that is, it determines that it is a non-contact state where the hand of the user is not touching). When the total capacitance of the touch sensor 17 is equal to or greater than the threshold value, the control device 18 determines that the contact condition is satisfied (that is, it determines that it is not a non-contact state). The control device 18 continuously executes in real time the process of acquiring the total capacitance of the touch sensor 17 and determining whether the contact condition is satisfied based on the acquired total capacitance. Note that this threshold value is a value appropriately set according to the configuration of the touch sensor 17 and the like, and is not particularly limited.

[0021] When the control device 18 detects that the start lever 15 has moved from the OFF position to the forward rotation position or the reverse rotation position when the contact condition is satisfied, that is, when the start switch 16 has switched from the OFF position to either of the two ON positions, the control device 18 operates the main shaft motor 13 (that is, rotates the main shaft 12). In this case, when the start lever 15 is in the forward rotation position, the control device 18 operates the main shaft motor 13 so that the main shaft 12 rotates forward, and when the start lever 15 is in the reverse rotation position, the control device 18 operates the main shaft motor 13 so that the main shaft 12 rotates in reverse. However, when the contact condition is not satisfied, the control device 18 does not operate the main shaft motor 13 (that is, does not rotate the main shaft 12). Further, when the control device 18 detects that the start lever 15 has moved from the forward rotation position or the reverse rotation position to the OFF position, even if it determines that the contact condition is satisfied, the control device 18 stops the operation of the main shaft motor 13 (that is, stops the rotation of the main shaft 12).

[0022] Furthermore, when the control device 18 determines that the contact condition no longer holds during the operation of the spindle motor 13, even if the start lever 15 is in the forward rotation position or the reverse rotation position, the control device 18 stops the operation of the spindle motor 13 (stops the operation of the spindle 12). And when the control device 18 stops the operation of the spindle motor 13 because it has determined that the contact condition no longer holds even though the start lever 15 is in the forward rotation position or the reverse rotation position, even if it is determined again that the contact condition holds, the control device 18 does not operate the spindle motor 13 (does not operate the spindle 12).

[0023] In this case, after the control device 18 stops the operation of the spindle motor 13, it first detects that the start lever 15 has moved to the OFF position (the start switch 16 has switched from one of the two ON positions to the OFF position), and then, when it detects that the start lever 15 has moved to the forward rotation position or the reverse rotation position (the start switch 16 has switched to one of the two ON positions), the control device 18 operates the spindle motor 13. In other words, when the control device 18 stops the operation of the spindle motor 13 because it has determined that the contact condition no longer holds, unless it first detects that the start lever 15 has moved to the OFF position, even if it is determined again that the contact condition holds, the control device 18 does not operate the spindle motor 13.

[0024] Therefore, the user can operate the spindle motor 13 by gripping the start lever 15 with the left hand and moving it from the OFF position to the forward rotation position or the reverse rotation position, and then continuously gripping the start lever 15 with the left hand. Then, while gripping the start lever 15 with the left hand (i.e., while maintaining the state where the left hand is in contact with the electrode 172 of the touch sensor 17), the user can machine the workpiece by operating the spindle lifting lever 14 with the right hand to lower the spindle 12. However, when the user releases the left hand from the start lever 15, the control device 18 determines that the contact condition is no longer satisfied, so the rotation of the spindle 12 stops even if the start lever 15 is in the forward rotation position or the reverse rotation position. In this case, even if the user touches the start lever 15 again, the spindle motor 13 does not operate. To operate the spindle motor 13, the user must first move the start lever 15 to the OFF position and then move the start lever 15 to the forward rotation position or the reverse rotation position.

[0025] According to such a configuration, when machining the workpiece, it is possible to prevent a free hand from occurring. That is, when the control device 18 detects that the start lever 15 has moved from the OFF position to the forward rotation position or the reverse rotation position and determines that the contact condition is satisfied, the control device 18 operates the spindle motor 13. Conversely, when the control device 18 determines that the contact condition is not satisfied, the control device 18 does not operate (or stops the operation of) the spindle motor 13 even if the start lever 15 is in the forward rotation position or the reverse rotation position. Therefore, in order to machine the workpiece, the user must operate the spindle lifting lever 14 with one hand (the right hand) while gripping the start lever 15 with the other hand (the left hand) (while maintaining the state where the other hand is touching the start lever 15). For this reason, a free hand does not occur.

[0026] In addition, in this embodiment, a capacitance-type touch sensor 17 is applied as the touch sensor 17. A plurality of electrodes 172 that are thinner (have a smaller cross-sectional area) than the grip portion 152 of the activation lever 15 are fitted into the groove 153 on the outer peripheral surface of the grip portion 152. With such a configuration, it is not necessary to increase the outer diameter of the grip portion 152 of the activation lever 15. Therefore, the grip portion 152 does not become larger.

[0027] Also, when a capacitance-type touch sensor 17 is applied as the touch sensor 17, the contact condition is established simply by the user's hand touching the electrode 172 provided on the outer peripheral surface of the activation lever 15. For this reason, since the user only needs to touch the activation lever 15 with the other hand, the other hand of the user can be prevented from getting tired (or the tiredness can be reduced). For example, when a pressure sensor is applied to the touch sensor 17, the control device 18 cannot detect that "the user is touching the activation lever 15" unless the user grips the grip portion 152 with a certain amount of force. Also, when a push-button switch is applied, the user has to keep pressing the push-button switch so that the push-button switch maintains the ON state. For this reason, since the user has to grip the activation lever 15 with a certain amount of force or keep pressing the push-button switch, the hand is likely to get tired.

[0028] Also, when a pressure sensor is applied to the touch sensor 17, the contact condition may not be satisfied when the user weakens the force with which they grip the activation lever 15. For this reason, in this case, a situation may occur in which the operation of the spindle motor 13 stops even though the user is touching the activation lever 15 (in other words, even though there is no play). Therefore, using the ball table 10 is inconvenient. In contrast, when a capacitance-type touch sensor is applied to the touch sensor 17, such a problem does not occur.

[0029] In addition, in this embodiment, a touch sensor 17 is provided on the start lever 15. With such a configuration, the operation of the ball disk 10 does not become complicated. That is, if the touch sensor 17 is provided at a portion other than the start lever 15, the user has to move the other hand to touch the touch sensor 17 after moving the start lever 15 from the OFF position to the forward rotation position or the reverse rotation position, or has to move the start lever 15 from the OFF position to the forward rotation position or the reverse rotation position while touching the touch sensor 17. Therefore, with such a configuration, the number of steps increases or the work becomes difficult. On the other hand, if the touch sensor 17 is provided on the start lever 15, after starting the operation of the main shaft motor 13 by moving the start lever 15 from the OFF position to the forward rotation position or the reverse rotation position, it is only necessary to hold the start lever 15 as it is, so the operation is simple.

[0030] And according to such a configuration, the user can operate the main shaft motor 13 (main shaft 12) by operating the start lever 15 with the other hand (left hand), and can maintain the operation (rotation) of the main shaft motor 13 (main shaft 12) by continuously holding the start lever 15 with the other hand (left hand). Then, while holding the start lever 15 with the other hand (left hand), the user can perform processing on the workpiece using the ball disk 10 by operating the main shaft lifting lever 14 with one hand (right hand).

[0031] <Processing executed by the control device> Next, the process executed by the control device 18 will be described. FIG. 4 is a flowchart showing the process executed by the control device 18. The control device 18 repeatedly and continuously executes the process shown in FIG. 4 at a predetermined short period. A computer program for executing the process of this flowchart is stored in advance in the ROM of the computer of the control device 18. Then, the CPU (hereinafter sometimes simply abbreviated as CPU) of the computer of the control device 18 reads out this computer program from the ROM, expands it in the RAM, and executes it. Thereby, the process shown in this flowchart is realized. At the start of the process, the operation of the spindle motor 13 is stopped.

[0032] In step S101, the CPU determines whether the contact condition is satisfied. If the contact condition is not satisfied, the CPU temporarily ends the execution of this program without operating the spindle motor 13. If the contact condition is satisfied, the CPU advances the process to step S102.

[0033] In step S102, the CPU determines whether the position of the start lever 15 is the OFF position (whether the start switch 16 is in the OFF position). If the position of the start lever 15 is not the OFF position, the CPU temporarily ends the execution of this program without operating the spindle motor 13. If the position of the start lever 15 is the OFF position, the CPU advances the process to step S103.

[0034] In step S103, the CPU determines whether the position of the start lever 15 has moved from the OFF position to the forward rotation position or the reverse rotation position. If the position of the start lever 15 has not moved from the OFF position to the forward rotation position or the reverse rotation position (that is, if the position of the start lever 15 is the OFF position), the CPU temporarily ends the execution of this program without operating the spindle motor 13. If the position of the start lever 15 has moved from the OFF position to the forward rotation position or the reverse rotation position, the CPU advances the process to step S104.

[0035] In step S104, the CPU starts the operation of the spindle motor 13. The rotation direction of the spindle motor 13 is the direction corresponding to the position of the start lever 15. Next, the CPU proceeds with the process to step S105.

[0036] In step S105, the CPU determines whether the contact condition is satisfied. If the contact condition is satisfied, the CPU proceeds with the process to step S106. Also, if the CPU determines in step S105 that the contact condition is not satisfied, the CPU proceeds with the process to S107.

[0037] In step S106, the CPU determines whether the position of the start lever 15 has moved from the forward rotation position or the reverse rotation position to the OFF position. If the position of the start lever 15 has not moved from the forward rotation position or the reverse rotation position to the OFF position (if it is currently still in the forward rotation position or the reverse rotation position), the process returns to step S105. In this case, the operation of the spindle motor 13 continues. If the position of the start lever 15 has moved from the forward rotation position or the reverse rotation position to the OFF position (if the start lever 15 is in the OFF position), the CPU proceeds with the process to step S107.

[0038] In step S107, the CPU stops the operation of the spindle motor 13. After that, the CPU temporarily terminates the execution of this program.

[0039] Through the above processing, the above operation is realized.

[0040] <Summary of the Embodiment> (1) The safety device 20 of the machine tool (the ball screw machine 10) according to this embodiment is a processing unit (the spindle 12) that operates by the driving force of a driving power source (the spindle motor 13) and performs processing on a workpiece, and a first operation member (the spindle lift lever 14) that is operated by a user with one hand (the right hand) when operating the processing unit (the spindle 12), and is a safety device 20 of a machine tool (the ball screw machine 10) including A contact sensor (touch sensor 17) that detects contact of the other hand (left hand) of the user, A control device 18 that controls the operation of the processing unit (spindle 12) by the driving power source (spindle motor 13), and is provided with When the other hand (left hand) of the user is not in contact with the contact sensor (touch sensor 17), the control device 18 stops the operation of the processing unit (spindle 12) by the driving power source (spindle motor 13).

[0041] According to this embodiment, when the other hand (left hand) of the user is not in contact with the contact sensor (touch sensor 17) (when the contact condition is not satisfied), the operation by the driving power source (spindle motor 13) of the processing unit (spindle 12) stops. Therefore, the user has to maintain the other hand (left hand) in a state of touching the contact sensor (touch sensor 17) in order to operate the first operation member (spindle lifting lever 14) with one hand (right hand) to perform processing on the workpiece. Thus, a free hand does not occur.

[0042] (2) A configuration in which the contact sensor (touch sensor 17) is a capacitance-type touch sensor can be applied.

[0043] According to such a configuration, the user only has to touch the capacitance-type touch sensor 17, so that fatigue does not occur in the other hand (left hand). For example, if a pressure sensor is applied instead of a capacitance-type touch sensor, pressure has to be applied to the pressure sensor, so fatigue is likely to occur. On the other hand, according to this embodiment, fatigue can be prevented.

[0044] (3) The machine tool (ball screw machine 10) includes a second operation member (start lever 15) that is operated by the other hand of the user, A configuration in which the contact sensor (touch sensor 17) is provided on the second operation member (start lever 15) can be applied.

[0045] According to such a configuration, the user can operate the second operation member (start lever 15) with the other hand and continue to hold the second operation member (start lever 15) as it is, thereby executing the machining by the machine tool (ball screw machine 10). Therefore, compared with the configuration in which the contact sensor (touch sensor 17) is provided at a location different from the second operation member (start lever 15), the operation is simple.

[0046] (4) The machine tool (ball screw machine 10) is a ball screw machine including a spindle lift lever 14 operated by the user when the spindle 12 moves, and a start lever 15 for switching between the stop and rotation of the spindle 12. The spindle 12 is the machining part. The spindle lift lever 14 is the first operation member. The configuration in which the start lever 15 is the second operation member can be applied.

[0047] According to such a configuration, the user operates the start lever 15 with the other hand (left hand) to operate the spindle motor 13 (operate the spindle 12 by the driving force of the spindle motor 13), and continues to hold the start lever 15 of the other hand (left hand) as it is, thereby maintaining the operation of the spindle motor 13 (the operation of the spindle 12 by the spindle motor 13). Then, while holding the start lever 15 with the other hand (left hand), the user can machine the workpiece by operating the spindle lift lever 14 with one hand (right hand).

[0048] As described above, the embodiments of the present invention have been described, but the technical scope of the present invention is not limited to the above embodiments. The present invention can be variously modified without departing from its gist, and these are also included in the technical scope of the present invention.

[0049] For example, in the above embodiment, a ball screw machine is shown as the machine tool, but the machine tool is not limited to the ball screw machine. As long as it is a machine tool including a processing unit configured to be able to perform processing on a workpiece by operating with the driving force of a driving power source, and a first operation member configured to be operable by a user with one hand to operate the processing unit, the safety device according to the present invention can be applied. Examples of the machine tool to which the present invention can be applied include a pipe machine, a container machine, a press brake, and a hoist crane.

Explanation of Signs

[0050] 10... Ball screw machine (machine tool), 12... Spindle (processing unit), 13... Spindle motor (driving power source), 14... Spindle lifting lever (first operation member), 15... Start lever (second operation member), 16... Start switch, 17... Touch sensor (contact sensor), 18... Control device, 20... Safety device

Claims

1. A machining unit that operates by the driving force of a driving power source and performs machining on a workpiece, A first operating member that is operated by a user with one hand during operation of the machining unit, A safety device for a machine tool comprising: A contact sensor that detects contact of the other hand of the user, A control device that controls the operation of the machining unit by the driving power source, Comprising: The control device stops the operation of the machining unit by the driving power source when the other hand of the user is not in contact with the contact sensor. A safety device for a machine tool.

2. The safety device for a machine tool according to Claim 1, The contact sensor is a capacitance-type touch sensor. A safety device for a machine tool.

3. The safety device for a machine tool according to Claim 1 or Claim 2, The machine tool comprises a second operating member that is operated by the user with the other hand, The contact sensor is provided on the second operating member. A safety device for a machine tool.

4. The safety device for a machine tool according to Claim 3, The machine tool is a lathe comprising a spindle lifting lever that is operated by the user when the spindle moves, and a start lever that switches between stopping and rotating the spindle, The spindle is the machining unit, The spindle lifting lever is the first operating member, The start lever is the second operating member. A safety device for a machine tool.

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