JPH0338066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application 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.

[Prior Art] Conventionally, in this type of machine tool, a drive torque applied to a rotational drive device such as a motor for rotating a tool or a rotation transmission member between the device and the tool is detected, and the drive torque is applied to the drive torque. Based on this, the cutting force applied to the tool at each time during forward movement of the tool is calculated, and when the magnitude of this cutting resistance becomes larger than a predetermined value, in order to prevent a tool breakage accident, Some were equipped with a load detection device that immediately caused the tool to move back.

In general, the method of determining the cutting resistance using this load detection device is such that the drive torque value of the rotation drive device or rotation transmission member can be detected every time the tool rotates once or several times.
First, the drive torque value when the tool is not loaded is determined, and then the drive torque value during machining is determined.
Next, the value obtained by subtracting the drive torque value during machining by the drive torque value under no load was determined as the cutting resistance applied to the tool. When the cutting resistance applied to the tool during machining determined by this method exceeds a predetermined value, the machining is stopped and the tool is immediately moved back.

However, at the beginning of the rotation of the rotary drive device, even though the tool is in an unloaded state, the driving torque rises significantly at the beginning of the rotation, as shown in Fig. 1, then gradually decreases, and then reaches a low value. Move to stable area. Therefore, as shown in Fig. 2, the drive torque value To under no load is detected at the point in time in the unstable state between when the drive torque gradually decreases and reaches a stable state, and the cutting process is performed based on this. If this is done, the value Tmo is the sum of the drive torque value To and a predetermined value (hereinafter referred to as set value) Ts set in advance to prevent tool breakage, based on that point in time.
When the driving torque value during machining exceeds the above value, that is,
When the cutting force Tx (=Tmo-To) applied to the tool exceeds the set value Ts, the tool is immediately moved back.

However, in the case of cutting in an unstable region of drive torque, the drive torque curve T that reaches the torque value Tmo is a state in which the drive torque as a whole gradually decreases over time and shifts to a stable region. Therefore, it becomes as shown by the dashed line in FIG.
Therefore, if the cutting resistance Tx is calculated from the torque value To while leaving the driving torque at no-load as is, the driving torque will be Torque value
Since Tmo has not been reached, cutting will continue. Then, the tool breaks.

Therefore, the present applicant filed an earlier patent application filed in 1983.
The invention of No. 15000 proposed a machine tool that prevents cutting by not moving the tool forward until the drive torque becomes stable, thereby preventing tool breakage accidents. In this prior invention, the limit switch detects that the drive torque has fallen below a certain value at the start of machining work, that is, that the drive torque has reached the stable region, and upon this detection, the tool is It is now being moved back and forth. However, since a limit switch is used, there are problems with the durability of the switch, and the constant value varies due to temperature differences, making it difficult to accurately determine whether the drive torque has reached a stable region. It was difficult.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems and to enable safe cutting by making it possible to observe the state in which the driving torque decreases until it moves from an unstable region to a stable region. Our goal is to provide machine tools that allow you to start work.

[Example] Hereinafter, an example in which the present invention is embodied in a drilling machine will be described based on the drawings.

In FIG. 3, a base end portion of a transmission spring 2 as a rotation transmission member is connected and fixed to a drive shaft 1a of a three-phase induction motor (hereinafter referred to as motor) 1 as a rotation drive device. The drive shaft 1a of the motor 1 is attached to the tip of the transmission spring 2.
The base end of a spline shaft 3 disposed on the same axis as the spline shaft 3 is connected and fixed, and the rotational force of the motor 1 is transmitted to the spline shaft 3. 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 to which the spline shaft 3 is fitted so as to be movable only in the axial direction. There is.

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 by a control circuit described later,
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 cylinder 8 is moved forward, and conversely, the air pump 1
When the air from the cylinder 4 is supplied to the second air cylinder chamber 12 and the air from the first air cylinder chamber 11 is discharged from the silencer 16, the main shaft cylinder 8 is moved back.

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, air cylinder 1
0 Above is the 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 FIG. 4, first, the drill 6 at the origin position P0 moves forward at a high speed toward the workpiece 17 while rotating, and at the first switching point P1 just before reaching the workpiece 17,
The forward speed is switched down by the feed control device (not shown) to a speed optimal for drilling and cutting,
Drilling begins at that speed. When a load (cutting resistance) above a certain level 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 back movement position Q near the origin position P0, and then 2nd switching point P2 immediately before reaching the bottom of the hole drilled for the first time from position Q
After moving forward at a fast speed up to , the speed is reduced to the optimum speed for drilling and cutting again as described above, and when a certain level of cutting resistance is applied to the drill 6, the speed returns to the backward movement position Q. Move back at speed.

In this way, the above-described operations are repeated until a predetermined depth D is reached, and when drilling and cutting are performed to the required depth D, the drill 6 moves back to the origin position P0 at a high speed. The drilling operation is then completed.

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

In FIG. 3, 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. 5, 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. As shown, 89 slits 19 as detected parts are connected to the spline shaft 3.
The disk 18 is transparently provided on the same circumference centering on the axis of the disk 18, and is fan-shaped from a position displaced by an angle of approximately 131 degrees in the rotational direction of the disk 18 with respect to the slit 19.
Fourteen through holes 20 are continuously provided on the same circumference with the axis of the spline shaft 3 as the center.

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 20 and a reference hole 24 that faces the through-hole position of the through-hole 20 are formed.
Furthermore, when the drive shaft 1a is in a stopped state, 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. Incidentally, 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 rotated to a sufficiently stable range and the main shaft 4, that is, the drill 6 is rotated with no load, the shielding plate 21 is moved against the rotating disk 18 by the elastic force of the transmission spring 2. Slight relative angular displacement in the rotational direction (in this example, the slit 8
The disc 18 is balanced and rotated at the same rotational speed as the disc 18 without any relative angular displacement. Therefore, in this state, the angular displacement detection photocoupler 25 detects the passing of 40 (=32+8) slits 19 every time the rotary disk 18 rotates once, and outputs 40 pulse detection signals equal to the number of slits 19 passed.
Output SG1.

Next, when a load torque is applied to the transmission spring 2 (for example, the cutting resistance Tx applied to the drill 6 or the drive torque generated when the motor 1 starts rotating), the shielding plate 21 is caused to move toward the rotating disk 18 due to the load torque. On the other hand, since the slit 19 is angularly displaced in the rotational direction in proportion to the magnitude of the torque, the slit 19 is newly exposed from the slit shielding portion 22 of the shielding plate 21 by the amount [k] of the angular displacement. Therefore, the angular displacement detection photocoupler 25 detects the passage of the slits 19 of the number (=40+k) which is the sum of the increased amount [k] every time the rotating disk 18 makes one revolution, and calculates the number of passages of the slits 19. (=40+k) pulse detection signals SG1 are output.

On the other hand, since the timing photocoupler 26 also displaces the reference hole 24 along with the displacement of the shielding plate 21,
The angular displacement detection photocoupler 25 detects passage of the reference hole 24 before the passage of the slit 19 begins, and outputs a timing pulse signal SG2. Therefore, the timing photocoupler 26 detects the slit 1 for each rotation by the angular displacement detection photocoupler 25.
Timing pulse signal SG is always sent before the passage of 9 is detected.
Outputs 2.

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

In FIG. 8, a central processing unit (hereinafter referred to as CPU) 31 as a control means has a read-only program memory (hereinafter referred to as ROM) in which program data for controlling the drilling machine and other various data are stored. )
32 and a readable and writable memory (Random Access Memory; hereinafter referred to as RAM) as a storage means for storing torque data based on the pulse detection signal SG1 of the photocoupler 25 for angular displacement detection.
) 33 constitutes an arithmetic and control unit. A start switch 34 is provided at a predetermined location on the drilling machine, and by pressing the switch 34, the start signal SG3 is sent through the I/O port 35a.
Output to CPU31. Then, in response to this activation signal SG3, the CPU 31 outputs a drive control signal to the motor drive circuit 36 via the I/O port 35b, thereby driving the motor 1 to rotate.

The origin position detection device 37 is composed of a photocoupler or a micro switch, and when the drill 6 is at the origin position P0 shown in FIG.
SG4 is connected to the CPU3 via the I/O port 35a.
It is designed to output to 1. The machining end detection device 38 is composed of a photocoupler, a micro switch, etc., and when the drill 6 moves forward to a predetermined depth D with respect to the workpiece 17 (when it reaches the drilling/cutting end position), End position signal SG
5 to the CPU 31 via the I/O port 35a.
It is now output to . Cutting resistance setting device 3
9 is a maximum cutting resistance value [X1] that is provided at a predetermined location on the drilling machine and is set according to the diameter of the drill 6 used in the drilling machine by an operator's operation.
data can be set, and the set data is output to the CPU 31. The double-movement position detection device 45 is composed of a photocoupler, a micro switch, etc., and outputs a double-movement position signal SG6 to the CPU 31 via the I/O port 35a when the drill 6 is at the double-movement position Q shown in FIG. It's becoming like that.

The counter 40 is the photocoupler 2 for detecting angular displacement.
The pulse detection signal SG1 output from 5 is added and counted, and the count value is read out by the CPU 31 and stored in the RAM 33 as torque data.
The data is stored at a predetermined address. The timing pulse signal SG2 output from the timing photocoupler 26 is a signal for reading and clearing the count value of the counter 40, and the CPU 31 responds to the rising signal of the pulse signal SG2 to read out and clear the count value of the counter 40. The count value is read out and stored in the RAM 33, and then the same count value is cleared.

The valve drive circuit 41 switches the electromagnetic valve 13 based on a drive control signal from the CPU 31, and moves the drill 6 forward and backward. The display device 42 includes 10 display devices 42a to 4 arranged at predetermined locations on the drilling machine.
2j, and these indicators 42a to 42j are controlled to turn on and blink based on a drive signal control signal output from the CPU 31 to the display drive circuit 43.

Next, the operation of the drilling machine configured as described above will be explained with reference to flowcharts of the arithmetic processing operations of the CPU 31 shown in FIGS. 9 to 11.

Now, from the state where the drill 6 is at the origin position P0,
When the worker presses the start switch 34, the start signal is activated.
SG3 is output to CPU31. In response to this starting signal SG3, the CPU 31 outputs a normal rotation drive control signal to the motor drive circuit 36 to start the motor 1 in normal rotation. Subsequently, the CPU 31 moves to an arithmetic processing operation according to the torque detection subroutine (see FIG. 11) and starts detecting the driving torque applied to the transmission spring 2.

When the motor 1 starts, the rotating disk 18 and the shielding plate 21 start rotating, so that the CPU 3 first
1 clears the contents of the counter 40 in response to the rise of the timing pulse signal SG2 from the timing photocoupler 26, and causes the counter 40 to count the pulse detection signal SG1 output from the angular displacement detection photocoupler 25. Then, the counter 40 calculates the driving torque applied to the transmission spring 2 during one rotation by the pulse detection signal SG.
Count by the number of 1s. When the counter 40 finishes counting and the transmission spring 2 rotates once, the timing photocoupler 26 again detects passage of the reference hole 24 of the shielding plate 21, and the timing pulse signal SG2 is output from the photocoupler 26.

In response to the rising edge of the timing pulse signal SG2, the CPU 31 reads out the count contents of the counter 40, and stores it in the RAM 33 as torque data for one rotation of the transmission spring 2.
Store it at address 1. Subsequently, the CPU 31 clears the counter 40 and immediately outputs the pulse detection signal SG output from the angular displacement detection photocoupler 25.
A count of 1 is started, and drive torque detection for the next rotation of the transmission spring 2 is started. After the counter 40 counts the drive torque of the second rotation of the transmission spring 2 in the same manner as described above, the timing pulse signal SG2 is output from the timing photocoupler 26 in the same manner as described above, and based on the rise of this signal SG2, , the CPU 31 reads the contents of the counter 40 and stores it in the RAM 33 as torque data for the second rotation of the transmission spring 2.
Store it at address 2.

When the storage of the torque data in address 2 of RAM 33 is completed, the CPU 31 first stores the torque data in address 1 of RAM 33.
The torque data value [T1] stored in RAM33
Perform a subtraction calculation using the torque data value [T2] stored at address 2, and obtain the calculated value [Y1 (=T1−
T2)] is positive. The determination as to whether this calculated value [Y1] is positive is made when the motor 1 starts to start up, and as shown in FIG.
The driving torque T
This is to judge whether or not the torque has reached the maximum drive torque value Tmax. At this point, since the motor 1 has just started starting, the transmission spring 2
As the motor rotates, the drive torque increases toward the maximum drive torque value Tmax. Therefore, the calculated value [Y1] is negative at this point.

When the CPU 31 determines that the calculated value [Y1] is negative, that is, the drive torque T applied to the transmission spring 2 has not yet reached the maximum drive torque value Tmax, it immediately transfers the torque data value [T2] stored at address 2 of the RAM 33. The pulse detection signal SG from the angular displacement detection photocoupler 25 is stored in address 1 of the RAM 33, and the counter 40 is cleared.
A count of 1 is started, and drive torque detection in the next rotation (third rotation) of the transmission spring 2 is started. Then, in exactly the same way as above, find the driving torque of the third rotation applied to the transmission spring 2.
Stored as torque data in address 2 of the RAM 33, and calculated value [Y1=(T2-T3)] based on the torque data value [T2] of the second rotation and the torque data value [T3] of the third rotation. The driving torque applied to the transmission spring 2 is the maximum driving torque value.
Determine whether Tmax has been reached. Then, the CPU 31 repeats the same calculation processing operation as described above until the drive torque applied to the transmission spring 2 reaches the maximum drive torque value Tmax.

When the driving torque applied to the transmission spring 2 reaches the maximum driving torque value Tmax (from this point onwards, the driving torque applied to the transmission spring 2 shifts to an unstable region where it gradually decreases), the CPU 31 sets the cutting resistance value set in advance by the cutting resistance setting device 39. The maximum cutting resistance value [X1] is read out and stored in address 3 of the RAM 33, and it is determined whether this resistance value [X1] is smaller than a reference value preset within the CPU 31. This judgment is based on whether the diameter of the drill 6 is small (that is, it is easy to cut even if a small cutting force Tx is applied),
In this example, for convenience of explanation, the reference value is set to "30" and the maximum cutting resistance value [X1 ] is larger than ``30'', it is determined to be a large diameter, and when it is smaller than ``30'', it is determined to be a small diameter.

If the drill 6 has a large diameter, when the drive torque of the transmission spring 2 moves from the maximum drive torque value Tmax to an unstable region where it gradually decreases, there is no risk of cutting damage even if the drill 6 is moved forward and cutting is performed. Therefore, in the case of this embodiment, after waiting for 0.4 seconds, the CPU 31 outputs a forward movement control signal to the valve drive circuit 41 to switch and control the electromagnetic valve 13, and moves the drill 6 forward from the origin position P0 to the machining position. let

On the other hand, when the drill 6 has a small diameter, the CPU 31 stores the torque data value stored in the address 2 of the RAM 33 in the address 1, and then waits for 0.2 seconds in this embodiment. After 0.2 seconds have elapsed, the CPU 31 executes arithmetic processing operations according to the torque detection subroutine, and
The driving torque applied to the transmission spring 2 after 0.2 seconds is counted by the counter 40 in the same manner as described above. Then, the counting operation of the counter 40 is completed, and in response to the rise of the timing pulse signal SG2 from the timing photocoupler 26,
The CPU 31 reads the contents of the counter 40 and stores it in address 2 of the RAM 33 as torque data when the transmission spring 2 rotates 0.2 seconds later.

When the storage of the torque data in address 2 of RAM 33 is completed, the CPU 31 first stores the torque data in address 1 of RAM 33.
Subtract the torque data value stored in address 2 of the RAM 33 by the torque data value stored in address 2 of the RAM 33, and calculate the reduction value [Y2] of the driving torque 0.2 seconds later in the unstable region where the driving torque gradually decreases. do. Next, CPU31 is this reduced value [Y2]
is subtracted in the CPU 31 by a torque reduction reference value [X2] as a second set value that is equal to or smaller than the maximum cutting resistance value [X1] of the cutting resistance setting device 39. Perform a calculation and determine whether the calculated value [Z2 (=Y2−X2)] is negative. To determine whether this calculated value [Z2] is negative or not,
During the transition from an unstable region where the driving torque applied to the transmission spring 2 gradually decreases to a stable region, it is determined whether the driving torque has reached the stable region.At this point, the driving torque is at the maximum driving torque value. Since it is in an unstable region where it gradually decreases after Tmax, the decrease value [Y2] is much larger than the torque decrease reference value [X2]. Therefore, the calculated value [Z2] is positive at this point. Note that the value of the torque reduction reference value [X2] is determined by the value of the driving torque that changes as shown in Fig. 1, and if cutting is performed in the middle of the reduction, the cutting resistance Tx applied to the drill 6 will decrease. It is set to a value that is not offset by the driving torque (i.e., a reduced value when the driving torque is in a stable region), and in this embodiment, it is the same as the maximum cutting resistance value [X1] of the cutting resistance setting device 39. value.

When the CPU 31 determines that the calculated value is positive, that is, that the driving torque applied to the transmission spring 2 has not yet reached the stable region, it then converts the calculated value [Z2] into the torque to calculate the reduction rate [α%] of the driving torque. Executes the calculation of dividing by the reduction reference value [X2].
Then, CPU31 calculates this reduction rate [α%]
Based on this, a display control signal is output to the display drive circuit 43, and the number of display devices 42a corresponding to the reduction rate [α%] among the 10 display devices 42a to 42j is
Turn on the lights in order from the sides. Therefore, the reduction rate [α%]
is 30%, the CPU 31 displays the display 42.
The three indicators a, 42b, and 42c are turned on, and when it is 60%, the six indicators from the display 42a to the display 42f are turned on. Note that in this example, the reduction rate [α
%] is 41%, for example, the first digit is "1" ~
If there is a value of "9", truncate the first digit.
40%, and four indicators from display 42a to display 42d are lit. Therefore, by simply observing the number of lit indicators among the indicators 42a to 42j, the operator can tell how much the drive torque is currently decreasing.

Next, the CPU 31 stores the torque data value stored in the address 2 of the RAM 33 in the address 1 of the RAM 33, and then waits for 0.2 seconds in the same manner as described above. After 0.2 seconds have elapsed, the CPU 31 calculates the driving torque applied to the transmission spring 2 after 0.2 seconds in the same manner as described above.
It is stored as torque data in address 2 of the RAM 33, and a decrease value [Y2] is calculated. continue
The CPU 31 obtains a calculated value [Z2] and determines whether this calculated value [Z2] is negative. Thereafter, the same process as described above is carried out until the drive torque reduction value [Y2] calculated every 0.2 seconds applied to the transmission spring 2 becomes smaller than the torque reduction reference value [X2], that is, until the drive torque reaches a stable region. The arithmetic processing operation is repeated, and each time the reduction rate [α%] of the drive torque is displayed by lighting on the indicators 41a to 42j.

When the reduction value [Y2] of the driving torque applied to the transmission spring 2 becomes smaller than the torque reduction reference value [X2] (when the driving torque moves to a stable region), the CPU 3
1 outputs a reciprocating control signal to the valve drive circuit 41 to switch and control the electromagnetic valve 13 to move the drill 6 forward from the origin position P0 to the processing position.
Therefore, the drill 6 of the drilling machine is not moved forward until the motor 1 is started and the driving torque applied to the transmission spring 2 reaches a stable range, and cutting is not performed.

When the drill 6 starts to move forward and passes the backward movement position Q in FIG. Similarly, the counter 40 counts,
The contents of the count are read out and stored in address 1 of the RAM 33, and then the counter 40 is operated to count in order to detect the driving torque during the next rotation of the transmission spring 2. Therefore, at this point, the torque data stored at address 1 of the RAM 33 is in a substantially stable region, and the drive torque data value (hereinafter referred to as loss torque data value) in a state where no cutting resistance [Tx] is applied to the drill 6 )
[Tloss].

Next, the CPU 31 inputs the counter 4 in the same manner as above.
After storing the contents of 0, that is, the driving torque applied to the transmission spring 2 in the next rotation as torque data in address 2 of the RAM 33, the counter 40 is cleared again for torque detection in the next rotation. And count operation. Then the CPU
31 calculates the cutting resistance value [Tx] applied to the drill 6 by subtracting the torque data value stored at address 2 of the RAM 33 by the loss torque data value [Tloss] stored at address 1 of the RAM 33. At the same time, the maximum cutting resistance value [X1] stored at address 3 of the RAM 33 is read out, and it is determined whether the cutting resistance [Tx] is larger than the maximum cutting resistance value [X1]. That is, this judgment determines whether the cutting resistance applied to the drill 6 during cutting has reached the maximum allowable cutting resistance of the drill 6.

At this point, the drill 6 has just started forward movement and is not cutting, so the cutting resistance [Tx] is 0, which is smaller than the maximum cutting resistance value [X1]. Therefore, the CPU 31 next calculates the ratio of the cutting resistance value [Tx] applied to the drill 6 at that time to the maximum cutting resistance value [X1] (hereinafter referred to as the resistance increase rate [θ%]).
Based on the resistance increase rate [θ%], the number of indicators 42a to 42j corresponding to the resistance increase rate [θ%] is turned on to display the same number of indicators as described above. However, at this point, as described above, the cutting resistance [Tx] is 0, so the CPU 31 does not turn on all the indicators 42a to 42j. Furthermore
The CPU 31 receives an end position signal from the machining end detection device 38 because the drill 6 has not moved forward to the machining end end.
Since SG5 is not output, the driving torque applied to the transmission spring 2 in the next rotation is detected again and the cutting resistance [Tx] is calculated, etc. After that, the drill 6 performs the same arithmetic processing operation as above to complete the cutting process. Repeat until moving to the position. Therefore, the indicators 42a to 42j are not lit because the cutting resistance [Tx] is 0 during this period.

When the drill 6 starts cutting, the driving torque applied to the transmission spring 2 also increases, and the RAM 3
Since the torque data value rewritten and stored at address 2 of 3 also increases, the cutting resistance value [Tx] also increases. Then, the resistance increase rate [θ%] is no longer 0, and the CPU 31 lights up and displays only the number of the indicators 42a to 42j corresponding to the resistance increase rate [θ%]. Therefore, by simply observing the lit numbers of the indicators 42a to 42j, the operator can determine how much the cutting resistance [Tx] of the drill 6 during cutting is relative to the maximum cutting resistance value [X1]. It is easy to see whether there has been an increase. Note that the increase rate [θ%] is, for example,
When the first digit such as 41% is "1" to "9", the first digit is truncated and displayed on the displays 42a to 42d, similarly to the reduction rate [α%].

When the cutting resistance [Tx] applied to the drill 6 becomes equal to or larger than the maximum cutting resistance value [X1], and the CPU 31 determines that, the CPU 31
outputs a backward movement control signal to the valve drive circuit 41, switches the electromagnetic valve 13, and moves the drill 6 backward to the backward movement position Q to prevent breakage.
Then, when the drill 6 returns to the double movement position,
The CPU 31 outputs a forward movement signal to the valve drive circuit 41 based on the backward movement position signal SG6 from the backward movement position detection device 45 to cause the drill 6 to move forward again.
Then, the cutting process is started again, and a new torque loss data value [Tloss] is first stored in address 1 of the RAM 33 in exactly the same manner as described above, and a cutting resistance value [Tx ]
, and calculate the resistance increase rate [θ
%] and controls the lighting of the indicators 42a to 42j.

Thereafter, the CPU 31 repeats the same arithmetic processing operation as described above until the drill 6 reaches the machining end position where machining of the workpiece 17 is completed, and lights up the indicators 42a to 42j based on the resistance increase rate [θ%] at each time. control and reciprocating motion control of the drill 6.

When the cutting of the workpiece 17 is completed and the drill 6 moves forward to the machining end position (when a hole of depth D is drilled in the workpiece 17), the end position signal SG5 is sent from the machining end detection device 38. is output.
In response to this end position signal SG5, the CPU 31
A backward movement control signal is output to the valve drive circuit 41, and the drill 6 is immediately moved backward in order to return to the home position P0. The CPU 31 receives an origin position signal SG output from the origin position detection device 37 when the drill 6 is returned to the origin position P0.
4, a stop control signal is output to the motor drive circuit 36 to stop the rotation of the motor 1. Then, the machining is completed in preparation for cutting the next workpiece 17.

As described above, in this embodiment, the drill 6 is not allowed to move forward until the driving torque applied to the transmission spring 2, which is necessary to obtain the cutting resistance value [Tx] of the drill 6 during cutting, reaches a stable region. Therefore, the cutting resistance value [Tx] of the drill 6 can be detected accurately and reliably, and based on this cutting resistance value [Tx], the reciprocating motion of the drill 6 can be controlled without breaking, allowing safe cutting work. It can be performed.

Also, the driving torque is the maximum torque value [Tmax]
, and at that point, the maximum cutting resistance value [X1] preset by the cutting resistance setting device 39 is compared with the reference value preset in the CPU 31. In other words, it is determined whether the drill 6 has a large diameter that can sufficiently withstand even when a large cutting force is applied, or the drill 6 has a small diameter that cannot withstand when a large cutting force is applied. In the case of , the cutting process (the drill 6 moves forward) is started after 0.4 seconds regardless of the state of the drive torque, and in the case of a small diameter drill 6, the drive torque reaches a stable region and the cutting resistance [Tx] increases. Since the CPU 31 controls the drill 6 not to move forward until the calculation is accurate, the work can be carried out efficiently depending on the type of cutting process.

Furthermore, in this embodiment, the reduction rate [α%] when the drive torque changes from the unstable region where it gradually decreases to the stable region is calculated, and the reduction rate [α%] is displayed on the ten indicators 42a to 42.
Since the number of indicators corresponding to the reduction rate [α%] of 2j is controlled to be lit, the operator can easily observe the extent to which the drive torque is decreasing, and the operator can easily observe the extent to which the drive torque is decreasing. It is possible to predict when the movement will start.

In this embodiment, the torque reduction reference value [X2]
is the maximum cutting resistance value of the cutting resistance setting device 39 [X1]
However, as shown by the broken line in Figure 8, a torque reduction amount setting device 44 is provided as a second setting device at a predetermined location of the drilling machine, and the torque reduction standard is set as appropriate according to the operator's operation. The value [X2] may be set so that the CPU 31 outputs it.

Based on this, the CPU 31 executes arithmetic processing operations according to the flowchart shown by the broken line in FIG. In other words, the CPU 31 has a reduced value [Y2]
After producing the torque reduction amount setter 44, read out the torque reduction reference value [X2] and set this value [X2]
The calculated value [Z2] may be calculated based on . Thereby, finer machining operations can be performed depending on the difference in the diameter of the drill 6.

The torque reduction reference value [X2] in the above embodiment is the 12th
Preset those values in ROM as shown in the figure
32 and read out according to the value [X1] of the cutting resistance setter 39.

Note that the present invention is not limited to the above-mentioned embodiments; for example, when calculating the reduction value [Y2], 0.2
Although the drive torque is detected every second by using the torsion of the transmission spring 2, it is also possible to detect the same drive torque at an appropriate time or every predetermined number of rotations, or to detect the drive torque by using the torsion of the transmission spring 2 every second. It is also possible to make appropriate changes without departing from the spirit of the invention, such as applying it to.

[Effects of the Invention] As described in detail above, according to the present invention, the state in which the drive torque gradually decreases until it shifts to a stable region can be observed on the display, and the timing for starting cutting can be observed. can be easily predicted.

[Brief explanation of drawings]

Fig. 1 is a torque curve diagram showing changes in the torque at the initial stage of rotation of the transmission spring, Fig. 2 is a curve diagram showing temporal changes in the driving torque of the transmission spring during cutting of a tool, and Fig. 3 is a curve diagram showing the change in torque of the transmission spring in the initial stage of rotation. Explanatory diagram showing the configuration of a drilling machine that embodies the 4th
The figure also shows a drill operation diagram to explain the operation of this drill press, Fig. 5 is a front view of the rotating disk, Fig. 6 is a front view of the shielding plate, and Fig. 7 shows the relationship between the rotating disk and the shielding plate. FIG. 8 is an electric block circuit diagram of the drilling machine, FIGS. 9 to 11 are flowcharts for explaining the arithmetic processing operations of the central processing unit, and FIG. 12 is a diagram of another implementation. It is a table showing the relationship between the maximum cutting resistance value [X1] and the torque reduction reference value [X2] in an example. In the figure, 1 is a three-phase induction motor as a rotation drive device, 2 is a transmission spring as a rotation transmission member,
6 is a drill as a tool, 8 is a main shaft cylinder, 9 is a piston, 10 is a cylinder, 13 is an electromagnetic valve, 18
is a rotating disk, 19 is a slit, 20 is a through hole, 21
25 is a shielding plate, 25 is a photocoupler for displacement detection as a torque detection device, 26 is a timing photocoupler, 31 is a central processing unit as a cutting resistance detection device and control means, etc., 32 is a program memory, 3
3 is a readable and writable memory as a storage means, 39 is a cutting resistance setting device as a first setting device, 40 is a counter, 42a to 42j are indicators,
44 is a torque reduction amount setting device as a second setting device.

Claims (1)

[Scope of Claims] 1. A rotary drive device 1 for applying rotational force to the tool 6; a reciprocating drive device 9, 10 for relatively reciprocating the tool 6 toward a workpiece 17; A torque detection device for detecting the magnitude of the drive torque applied to the rotational drive device 1 or the rotation transmission member 2 between the device 1 and the tool 6, and generating a detection signal SG1 according to the magnitude of the drive torque. 25, a cutting resistance detection device 31 for detecting the cutting resistance applied to the tool 6 based on the detection signal SG1 of the torque detection device 25, and a first setting device 39 for setting the magnitude of the cutting resistance. In a machine tool, the tool 6 is switched from forward movement to backward movement when the magnitude of the cutting resistance detected by the cutting resistance detection device 13 reaches a value set by the setting device 39. , a second setter 44 for variably setting the reference reduction amount of the drive torque with respect to unit time or unit number of rotations, and determining the reduction amount of the drive torque at the initial stage of rotation of the rotary drive device 1, and determining the reduction amount. Calculating means (such as 31) for calculating the ratio of the difference to the setting value of the second setting device 44 after subtracting the setting value of the second setting device 44 from the amount; A machine tool comprising displays 42a to 42j for displaying the ratios calculated by the calculation means (31, etc.).