JPS6236803B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a machine tool that processes a workpiece by rotating a tool and reciprocating the tool relative to the workpiece.

Conventional technology Conventionally, for example, in machine tools such as drilling machines,
In order to prevent the drill from breaking due to an increase in cutting resistance applied to the drill during cutting, a detection device that detects the cutting resistance of the drill and a maximum permissible limit for the drill are installed to prevent the drill from breaking. The machine was equipped with a setting device for setting the cutting resistance. When the cutting resistance applied to the drill during cutting becomes greater than the maximum allowable cutting resistance set by the setting device, cutting is immediately stopped to prevent drill breakage accidents. Ta.

However, the maximum allowable cutting resistance of a drill varies depending on the machining method, machining conditions, and the like. Moreover, the maximum allowable cutting resistance was set by the operator in accordance with the reference value described in the instruction manual. Therefore, if the setting values are not changed accurately according to the machining method and machining conditions, the drill may break or the drill may perform unnecessary step operations, making it difficult to perform safe and efficient machining operations. I couldn't do it.

Purpose The purpose of the present invention is to solve the above-mentioned problems by determining the ratio of the cutting resistance applied during cutting of the tool to the maximum allowable cutting resistance of the tool, which is preset by the setting device. In addition, in the unlikely event that a drill breaks due to large cutting resistance being applied to it during cutting, the cutting resistance that was applied to the same drill immediately before it broke will be set in the setting device. Provides a machine tool that allows safe and efficient machining work by displaying the display as a ratio of the set value set on the setter so that it can be easily determined whether the set value set on the setting device is an appropriate value. There is something to do.

Embodiment Hereinafter, an embodiment in which the present invention is embodied in a drilling machine will be described based on the drawings.

In FIG. 1, a base end portion of a transmission spring 2 is connected and fixed to a drive shaft 1a of a three-phase induction motor (hereinafter referred to as a motor) 1 as a rotational drive device. The base end of a spline shaft 3 disposed on the same axis as the drive shaft 1a of the motor 1 is connected and fixed to the distal end of the transmission spring 2, and the rotational force of the motor 1 is transferred to the spline shaft 3. to communicate. A drill 6 as a tool is attached to the tip of the main shaft 4 via a chuck 5, and a cylindrical portion 7 is provided at the base end into which the spline shaft 3 is fitted so as to be movable only in the axial direction.

The main shaft cylinder 8 supports the main shaft 4 rotatably and immovably in the axial direction, and has a piston 9 on its outer periphery.
is attached. The air cylinder 10 has the piston 9 inserted therein to constitute a reciprocating drive device, and a first air cylinder chamber 11 and a second air cylinder chamber 12 are provided with the piston 9 as a boundary. The electromagnetic valve 13 is switched and controlled by an electric control circuit to be described later, and when the air from the air pump 14 is supplied to the first air cylinder chamber 11 and the air from the second air cylinder chamber 12 is discharged by the silencer 16, the piston 9, that is, the main shaft The cylinder 8 is moved forward, and when the air from the air pump 14 is supplied to the second air cylinder chamber 12 and the air in the first air cylinder chamber 11 is discharged by the silencer 16, the main shaft cylinder 8 is moved backward.

Therefore, rotational force is applied to the drill 6 by the motor 1, and reciprocating motion is performed by switching the electromagnetic valve 13. Furthermore, above the air cylinder 10 is a patent application filed earlier by the applicant in 1982.
A feed control device (not shown) as shown in No. 153288 is provided, and a part of it is engaged when the main shaft cylinder 8 moves forward to control the feed rate. .

The drilling operation using this drilling machine is performed as follows. That is, as shown in Figure 2,
First, the drill 6 at the origin P0 rotates and moves forward at a fast speed toward the workpiece 17.
At a first switching point P1 just before reaching , the forward speed is switched down by the feed control device (not shown) to a speed optimal for drilling, and drilling is started at that speed. When a certain level of cutting resistance (cutting torque) is applied to the main shaft 4 holding the drill 6 due to the drilling, the drill 6 moves back at a high speed to the return position R near the origin position P0. Then, after moving forward at a high speed from the backward movement position R to the second switching point P2 just before reaching the bottom of the hole drilled for the first time, the speed is reduced to the optimum speed for drilling and cutting in the same manner as above. Then, drilling and cutting are performed again, and when a cutting resistance of a certain level or more is applied to the drill 6, the drill 6 moves backward at a high speed to the backward movement position R.

In this way, the above operations are repeated until a predetermined depth D is reached, that is, until the end of machining. When drilling and cutting are performed to the required depth D, the drill 6 returns to the origin position P0. The drilling operation is completed by moving back at a high speed.

Next, a torque detection device for detecting the driving torque applied to the transmission spring 2 will be explained.

In FIG. 1, a rotating disk 18 is fixed to the base end of the spline shaft 3 and rotates together with the spline shaft 3. In this embodiment, as shown in FIG. 3, the rotating disk 18 has 71 pieces at equal angular intervals of 1.5 degrees in the rotational direction of the disk 18, and thereafter the positions are arranged at intervals that increase exponentially. In addition, 89 slits 19 as detected portions are transparently provided on the same circumference centering on the axis of the spline shaft 3, and approximately 131 in the rotational direction of the disc 18 with respect to the slits 19. Fourteen fan-shaped through holes 20 are continuously provided on the same circumference about the axis of the spline shaft 3 from a position displaced by an angle of .degree.

The shielding plate 21 is fixed to the drive shaft 1a of the motor 1 so as to face the rotating disk 18, and rotates together with the drive shaft 1a. In this embodiment, the shielding plate 21 has the slits 19 when facing the rotating disk 18 as shown in FIG.
a slit shielding portion 22 that shields the through hole 20;
A through-hole shielding portion 23 that shields the through-hole and a reference hole 24 that faces the through-hole position of the through-hole 20 are formed.
In addition, the shielding plate 21 is positioned relative to the rotating disk 18 at the relative position shown by the dashed line in FIG. The location is as follows:

The angular displacement detection photocoupler 25 and the timing photocoupler 26 are respectively disposed on a support member (not shown) in the machine frame (not shown) as shown in FIG. The passage of the rotating disk 18 through the slit 19 is detected, and the timing photocoupler 26 is connected to the reference hole 2 of the shielding plate 21.
4 is detected. Note that even if the reference hole 24 passes through the timing photocoupler 26 in a state shown by the dashed line in FIG. It is now possible to do so.

Now, when the motor 1 is driven to rotate and the main shaft 4, that is, the drill 6 is rotated with no load, the elastic force of the transmission spring 2 causes the shielding plate to
1 is balanced with a slight relative angular displacement (eight slits in this example) in the rotational direction with respect to the rotating disk 18, and has the same rotational speed as the same disk 18 without causing any relative angular displacement. It is rotated by Therefore,
In this state, the photocoupler 25 for angular displacement detection is 40 (=32+8) every time the rotating disk 18 makes one rotation.
40 pulse signals equal to the number of slits 19 passed through are outputted as driving torque applied to the transmission spring 2 in the no-load state.

Next, when a load torque (for example, cutting resistance applied to the drill 6) is applied to the transmission spring 2, the load torque causes the shielding plate 21 to move in the rotational direction relative to the rotating disk 18 in proportion to the magnitude of the torque. Due to the relative angular displacement, the angular displacement [k]
The slit 19 is newly exposed from the slit shielding portion 22 of the shielding plate 21. Therefore, the angular displacement detection photocoupler 25 detects the number (=40
+k) passing through the slit 19 is detected, and a number of pulse signals equal to the number of pulse signals passed through are outputted as driving torque in a loaded state.

On the other hand, since the timing photocoupler 26 also displaces the reference hole 24 with the displacement of the shielding plate 21, the angular displacement detection photocoupler 25 detects the passing of the reference hole 24 before the slit 19 starts passing, and the timing Outputs a pulse signal. Therefore, the timing photocoupler 26 outputs a timing pulse signal before the angular displacement detection photocoupler 25 detects passage of the slit 19 for each rotation.

Next, a control circuit for driving and controlling the drilling machine configured as described above will be explained with reference to FIG.

In FIG. 6, a central processing unit (hereinafter referred to as CPU) 31 as a control means is a read-only program memory (hereinafter referred to as read-only memory) in which program data for controlling the drilling machine and various other data are stored. ROM) 32, and a readable and writable memory (Random) as a storage means for storing data of the driving torque applied to the transmission spring 2.
Access Memory (hereinafter referred to as RAM) 33 constitutes an arithmetic and control unit. Start switch 3
4 is provided at a predetermined location on the drilling machine, and by pressing the switch 34, the start signal SG1 is switched to I/O.
It is output to the CPU 31 via the O port 35. Then, in response to this activation signal SG1, the CPU 31 outputs a drive control signal to the motor drive circuit 37 via the I/O port 36, thereby driving the motor 1 to rotate. The reset switch 38 is provided at a predetermined location on the drilling machine.
By pressing 8, reset signal SG2 is set to I/
It is output to the CPU 31 via the O port 35. The CPU 31 is adapted to return to its initial state in response to this reset signal SG2.

The origin position detection circuit 39 is composed of a photocoupler, a micro switch, etc., and when the drill 6 is at the origin position P0 shown in FIG.
The SG3 is connected to the CPU 31 via the I/O port 35.
It is now output to . The machining end detection circuit 40 is composed of a photocoupler, a micro switch, etc., and when the drill 6 moves forward to a required depth D set in advance with respect to the workpiece 17 (when it reaches the cutting end position), the end of the machining is terminated. The position signal SG4 is output to the CPU 31 via the I/O port 35. The double-movement position detection circuit 41 is composed of a photocoupler, a micro switch, etc.
When the drill 6 is at the return position R shown in FIG. 3, a return position signal SG5 is output to the CPU 31 via the I/O port 35.

The drive torque detection circuit 42 includes the angular displacement detection photocoupler 25, the timing photocoupler 26, and a counter (not shown) that counts the pulse signal from the photocoupler 25 every time the rotating disk 18 rotates once. , detects the driving torque and outputs it to the CPU 31. The step torque value setter 43 is provided at a predetermined location on the drilling machine, and is used to set the maximum permissible cutting resistance standard for the cutting force applied to the drill 6 when the drill 6 used in the drilling machine is changed from forward motion to backward motion by an operator's operation. The value [X1] can be set appropriately, and the set resistance reference value [X1] is output to the CPU 31.

The drill breakage value setter 44 is provided at a predetermined location on the drilling machine, and is used to set a breakage reference value [Q] for the CPU 31 to determine whether or not the drill 6 has broken, by an operator's operation. The set breakage reference value [Q] is output to the CPU 31.

The valve drive circuit 45 is configured to switch and operate the electromagnetic valve 13 based on a drive control signal from the CPU 31.
to move forward and backward. The display device 46 includes ten display devices 46a to 46a arranged at predetermined locations on the drilling machine.
46j, and their indicators 46a to 46j
The lighting and blinking display is controlled based on a drive control signal outputted from the CPU 31 to the display drive circuit 47.

Next, the operation of the drilling machine configured as described above will be explained with reference to the flowchart of the arithmetic processing operation of the CPU 31 shown in FIG.

Now, when the operator presses the start switch 34 from the state where the drill 6 is at the home position, the start signal SG1
is output to the CPU 31. After starting the motor 1 by outputting a normal rotation drive control signal to the motor drive circuit 37 in response to the start signal SG1, the CPU 31 waits for 0.5 seconds. This 0.5 second waiting period takes into consideration the time required for the motor 1 to reach a stable state with little fluctuation at the initial stage of rotation.

After 0.5 seconds have elapsed, the CPU 31 reads out the drive torque value [T0] in the no-load state at that time from the drive torque detection circuit 42 and stores it in addresses 1 and 3 of the RAM 33. Subsequently, the CPU 31 outputs a forward movement control signal to the valve drive circuit 45 to switch and control the electromagnetic valve 13 to move the drill 6 forward from the origin position P0 to the processing position.

When the drill 6 starts to move forward, the CPU 31 reads a new drive torque value [T] applied to the transmission spring 2 for each rotation during the forward movement from the drive torque detection circuit 42, and rewrites and stores it in address 2 of the RAM 33. At the same time, in order to obtain the cutting force [Tx] applied to the drill 6 for each rotation, a new drive torque value [T] for each rotation of the transmission spring 2 is stored in address 1 of the RAM 33 as the no-load drive torque value [ T0] executes the subtraction operation. Then, the CPU 31 sequentially compares the cutting resistance [Tx] applied to the drill 6 for each rotation with the resistance reference value [X1] read from the step torque value setting circuit 43, and determines that the cutting resistance [Tx] is higher than the resistance reference value. When it is determined that the cutting force is smaller than the value [X1], the ratio of the cutting force [Tx] obtained for each revolution to the resistance reference value [X1] (hereinafter referred to as resistance ratio) [θ% (=Tx/X1) ] is calculated. Then, the CPU 31 outputs a display control signal to the display drive circuit 47 based on the calculated resistance ratio [θ%], and displays only the number corresponding to the internal resistance ratio [θ%] of the 10 displays 46a to 46j. The lights are turned on in order from the side of the container 46a. Therefore, the resistance ratio [θ%] is 30%
, the CPU 31 displays the indicators 46a and 4.
The three indicators 6b and 46c are turned on, and when it is 60%, the six indicators from the display 46a to the display 46f are turned on. In addition, in this example, the resistance ratio [θ
%] is written as 31%, for example, the first digit is "1".
If there is a value of ~9, all values are rounded down to 30%, and the three indicators from display 46a to display 46c are illuminated. Therefore, by simply observing the number of lit indicators among the indicators 46a to 46j, the operator can determine how much cutting resistance [Tx] currently being applied to the drill 6 is relative to the resistance reference value [X1]. You can easily find out what the percentage is.

Furthermore, the CPU 31 determines whether or not there is a breakage accident (an accident that occurs when the resistance reference value [X1] is set to a large value due to a setting error) due to an increase in the cutting resistance [Tx] of the drill 6 during forward movement of the drill 6. In order to achieve this, the no-load drive torque value [T0] stored at address 3 of the RAM 33 is subtracted by the new drive torque value [T] after the next rotation of the transmission spring 2 to obtain the resistance reduction value [Z1]. calculate. and,
The CPU 31 uses the resistance reduction value [Z1] and the breakage reference value [Q] read from the drill breakage value setter 44.
It is determined whether the drill 6 is broken or not. If the drill 6 is not broken, the drive torque [T] stored at address 2 of the RAM 33 is rewritten and stored at address 3. Therefore,
Unless the drill 6 is broken, the content stored in the RAM 33 is rewritten to the drive torque [T] stored at address 2 after determining whether or not the drill 6 is broken. In other words, the determination as to whether the drill 6 is broken is made by determining whether the resistance reduction value [Z1] is 0 or a positive value, because if the drill 6 is broken, the resistance reduction value [Z1] becomes 0 or a positive value. It is determined whether the drill 6 is broken or not by determining whether the value is the same or not. In this embodiment, the breakage reference value [Q] may be set to 0, but the cutting resistance [Tx] of the drill 6 may be slightly lower for some reason, not because of breakage. Since it may decrease during cutting, a desired positive integer value is set by the drill breakpoint value setter 44 in order to prevent malfunctions due to this.

Therefore, if the cutting force [Tx] applied to the drill 6 during cutting is less than the resistance reference value [X1], the CPU 31 continues the cutting process, and also controls the cutting force [Tx] applied to the drill 6 from time to time. ] is displayed on the displays 46a to 46j in proportion to the resistance reference value [X1].

Then, when the cutting resistance [Tx] of the drill 6 becomes larger than the resistance reference value [X1] while the drill 6 is moving forward during cutting, the CPU 3
1 outputs a double-acting control signal to the valve drive circuit 45, switches the electromagnetic valve 13, and operates the drill 6.
Immediately move back to return position R. Then, when the drill 6 returns to the double movement position R, a double movement position signal is output from the double movement position detection circuit 41.
In response to SG5, the CPU 31 reads the drive torque value [T0] of the transmission spring 2 in the no-load state at that time from the drive torque detection circuit 42 in the same manner as described above, and stores the previous contents in addresses 1 and 3 of the RAM 33. The drill 6 is rewritten and stored, and the drill 6 is moved forward to start cutting again.

Thereafter, the CPU 31 repeats the same arithmetic processing operation as described above until the drill 6 reaches the machining end position where the cutting of the workpiece 17 is finished without breaking, and calculates the resistance ratio [θ%] at each time. Based on this, the lighting control of the indicators 46a to 46j and the reciprocating movement control of the drill 6 are performed.

When the cutting of the workpiece 17 is completed and the drill 6 moves forward to the machining end position, the machining end detection circuit 40 outputs the end position signal SG4. In response to this end position signal SG4, the CPU 31 outputs a lights-off control signal to the display drive circuit 47 to turn off the lights of each display 46a to 46j, and outputs a return control signal to the valve drive circuit 45 to turn off the drill 6. It is immediately moved back to return to the origin position P0. The CPU 31 receives a home position signal SG output from the home position detection circuit 39 when the drill 6 is returned to the home position P0.
3, a stop control signal is output to the motor drive circuit 37 to stop the rotation of the motor 1. Then, the machining is completed in preparation for cutting the next workpiece 17.

On the other hand, because the resistance reference value [X1] was set to a large value due to a setting error, the drill 6 was not moved back and the cutting process continued, causing the drill 6 to break during the cutting process. When the resistance decrease value [Z1] is the breakage reference value [Q]
When the size of the drill 6 becomes larger than
The drive torque [T] that was applied to the transmission spring 2 of the drill 6 just before it broke, which is stored at address 1, and the drive torque [T0] in the no-load state, which is stored at address 1, are read out. Then, the CPU 31 converts the driving torque [T] into the driving torque in the no-load state [T0].
The breakage resistance [Y1] is obtained by subtracting the breakage resistance [Y1], and the breakage resistance ratio [Φ%] is calculated by dividing the breakage resistance [Y1] by the resistance reference value [X1]. That is, the cutting resistance [Y1] is determined with respect to the resistance reference value [X1], and the ratio is calculated. Next, the CPU 31 controls the display drive circuit 47 based on the calculated breakage resistance ratio [Φ%].
The display control signal is output to the 10 display devices 46a~
The number corresponding to the internal breakage resistance ratio [Φ%] of 46j is blinked in order from the display 46a side. Therefore, if the breakage resistance ratio [Φ%] is 70%,
The CPU 31 causes the seven displays from the display 46a to the display 46g to blink. This allows the operator to set the resistance reference value [X1] 30% smaller than the current resistance reference value [X1], thereby ensuring that the resistance reference value [X1] is accurate and reliable from now on, thereby preventing accidents from breaking the drill 6. can.

In addition, in this embodiment, the blinking display control of the indicators 46a to 46j based on the breakage resistance ratio [Φ%] is performed when the first digit is "1" to "9" such that the breakage resistance ratio [Φ%] is 31%. ”, the value of that digit is rounded down to 30%, and the value is displayed from display 46a to display 46c.
The first three are made to flash to provide a margin of safety when modifying the resistance reference value [X1].

Subsequently, the CPU 31 outputs a backward movement signal to the valve drive circuit 45 to switch the electromagnetic valve 13, thereby causing the drill 6 to move backward to the home position P0. When the drill 6 returns to the home position P0 and the home position detection circuit 39 outputs the home position signal SG3,
In response to this origin position signal SG3, the CPU 31
A stop control signal is output to the motor drive circuit 37 to stop the motor 1.

Then, based on the stoppage of the motor 1, the operator replaces the drill 6 and displays the indicators 46a to 46a.
The resistance reference value [X1] is corrected by operating the step torque value setter 43 based on the number of indicators blinking in 46j. Next, when the operator presses the reset switch 38, a reset signal SG2 is output to the CPU 31, and in response to this reset signal SG2, the CPU 31 turns off the flashing display and then starts cutting again. In order to do so, it waits for the activation signal SG1 from the activation switch 34.

As described above, in this embodiment, the indicators 46a to 46j are lit as the ratio [θ%] of the cutting resistance [Tx] applied to the drill 6 during cutting to the preset resistance reference value [X1]. Since it is expressed by the number of indicators, the operator can now drill 6.
It is possible to easily know the ratio of the cutting force [Tx] applied to the resistance value [X1] to the resistance reference value [X1], and it is possible to predict the timing of the return movement of the drill 6 and perform machining work safely. .

In addition, when the drill 6 breaks, the breakage resistance [Y1] applied to the drill 6 at that time is set as a ratio [Φ%] to the resistance reference value [X1], and the indicators 46a to 46j blink. Since it is expressed by the number of indicators, the step torque value setting device 4
Resistance reference value previously set by 3 [X1]
It is easy to judge how much error there is.

Therefore, from now on, accurate and reliable resistance standard [X1]
can be set, and not only can breakage accidents of the drill 6 be prevented, but also safe and efficient cutting work can be performed without unnecessary step movements.

Note that the present invention is not limited to the above-described embodiment; for example, if the cutting resistance [Tx] applied to the drill 6 during cutting becomes larger than the resistance reference value [X1], the drill 6 is immediately moved back to the return position. After that, the drill 6 was moved forward again, but the feed control device did not move the drill 6 back.
The cutting process may be continued by slowing down the forward movement speed and reducing the cutting resistance [Tx].

Further, although the cutting resistance is detected every time the rotary disk 18 rotates once, it may be detected at predetermined time intervals.

Effects As detailed above, the present invention is capable of displaying the ratio of the cutting resistance applied during cutting of the tool to the maximum allowable cutting resistance of the tool preset by the setting device. In the unlikely event that a drill breaks during machining, it is possible to display the ratio of the cutting resistance applied to the drill just before the breakage to the cutting resistance set with the setting device. This has the effect that it is possible to easily judge whether the setting values set in the setting device are appropriate, and also to perform safe and efficient machining work.

[Brief explanation of the drawing]

Fig. 1 is a mechanical diagram showing the mechanism of a drilling machine embodying this invention, Fig. 2 is an operating diagram of the step feed of the drill of this invention, Fig. 3 is a front view of the rotating disk, and Fig. 4 is a shielding plate. 5 is a side view showing the relative positional relationship between the rotating disk and the shielding plate, FIG. 6 is an electrical block circuit diagram, and FIG. 7 is a flowchart for explaining the arithmetic processing operation of the central processing unit. It is a diagram. Three-phase induction motor 1 as a rotational drive device, transmission spring 2, spline shaft 3, main shaft 4, drill 6 as a tool, main shaft cylinder 8, piston 9 as a reciprocating drive device, air cylinder 10, electromagnetic valve 1
3, air pump 14, workpiece 17, rotating disk 1
8, slit 19, shielding plate 21, angular displacement detection photocoupler 25, central processing unit 31 as control means and detection means, read-only program memory 32, readable and writable memory 33 as storage means, starting switch 34, reset switch 38, drive torque setting device 43 as a torque detection device, drill breaking value setting device 44, display device 4
6. Indicators 46a to 46j as display units.

Claims (1)

[Claims] 1. A rotary drive device 1 for applying rotational force to a tool 6; and reciprocating drive devices 9 and 10 for relatively reciprocating the tool 6 toward a workpiece 17. A machine tool comprising: a detection device 42 for detecting the magnitude of cutting resistance applied to the tool 6, and a setting device 43 for setting the magnitude of the cutting resistance according to the method of machining the workpiece 17. and the magnitude of the cutting resistance detected by the detection device 42 etc. is compared with the value set by the setting device 43, and the reciprocating drive devices 9 and 10 are controlled according to the comparison result. and a display device 46 for displaying the ratio of cutting resistance detected by the detection device 42 or the like to the setting value of the setting device 43. 2 The display device 46 includes a large number of display sections 46a to 46j arranged in one direction, and among them, a display corresponding to the ratio of the cutting resistance detected by the detection device 42 etc. to the setting value of the setting device 43. Part 4
The machine tool according to claim 1, wherein the machine tool is configured to be lit from one side by the number of lights from 6a to 46j. 3. The detection device includes: a torque detection device 42 for detecting the drive torque provided between the rotary drive device 1 or the tool 6; a storage means 33 for storing the magnitude of the driving torque detected by the torque detection device 42; The control means includes a comparison means 31 for determining the difference between the magnitude of the detected driving torque and the value stored in the storage means 33 as the magnitude of cutting resistance applied to the tool 6, and the control means includes the detection device 42. When the magnitude of the cutting resistance detected by, for example, is smaller than the setting value of the setting device 43, calculating means 31 for calculating the ratio of the difference to the setting value is displayed on the display device 46. A machine tool according to claim 1, characterized in that it includes: 4. The control means controls the rotary drive device 1 at predetermined time intervals or at least when the tool 6 is relatively moved toward the workpiece 17 and is machining the workpiece 17.
The change in the value of cutting resistance detected by the detection device 42 etc. is determined every predetermined number of rotations of an abnormality detection means 31 for generating an abnormality signal when the abnormality detection means 31 generates an abnormality signal when the abnormality detection means 31 generates an abnormality signal;
3. The machine tool according to claim 1, further comprising calculation means 31 for calculating a ratio of 3 to a set value so as to be displayed on the display device 46.