JP2009160690A - Numerical control device, numerical control program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a clamping force accurately with a simple constitution. <P>SOLUTION: A machine tool is provided with: a spindle rotatably mounted on the spindle head; and a drover mounted on the spindle and equipped with a clamp spring for clamping a tool holder onto the spindle by means of the spring force of the clamp spring. The numerical control device 24 is also provided with: a control device 25; an indicator 39; and others. The control device 25 functions as a detection means to detect the spring force of the clamp spring and as a comparison means to compare the spring force detected by the detection means with a predetermined reference value, and then notifies the indicator 39 of the results from the comparison means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a numerical control device and a numerical control program for a machine tool, comprising a clamp spring, a draw bar for clamping the tool holder to the main shaft by the spring force of the clamp spring, and detecting the spring force of the clamp spring. And a storage medium.

  2. Description of the Related Art Conventionally, a tool changer for a machine tool is provided with a draw bar on a main shaft that is movable in the axial direction, and a clamp spring that urges the draw bar in a clamping direction, and the draw bar resists the spring force of the clamp spring. There is a configuration in which an operation unit to be pushed down is provided. In this case, when the draw bar is pushed down by the operation portion, the chucking portion under the draw bar can be expanded, and the chucked tool holder is removed. Then, the upper part of the tool holder to be replaced in this depressed state is inserted into the chucking part, and the draw bar is moved upward by the spring force (restoring force) of the clamp spring, so that the chucking part is The tool holder is chucked (clamped) by holding and pulling.

In this tool changer, when the clamping force with respect to the tool holder is reduced, there is a concern that the processing capability may be reduced or the tool holder may be dropped. From such a viewpoint, an apparatus for measuring a clamping force is provided (for example, Patent Document 1). In this configuration, the strain amount of the clamp spring made of a disc spring is mechanically measured. That is, when the strain amount is large, the upper end of the tool holder turns on the switch.
JP 2003-39280 A

  However, in Patent Document 1, since the amount of strain of the clamp spring is measured, the clamping force (clamping force) with respect to the tool holder cannot be accurately detected, and there is a drawback that the reliability of the clamping force determination is low. It was.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a numerical control device, a numerical control program, and a storage medium that can detect a clamping force with high accuracy and perform maintenance and inspection so that the tool holder can always be securely clamped. Is to provide.

The invention of claim 1 includes a main shaft rotatably provided on the main shaft head, and a draw bar that is provided on the main shaft and includes a clamp spring and clamps the tool holder on the main shaft by the spring force of the clamp spring. In a numerical control device that controls a machine tool,
Detection means for detecting the spring force of the clamp spring, comparison means for comparing the spring force detected by the detection means with a preset reference value, and notification means for notifying the comparison result of the comparison means are provided. It was.

  In the invention of claim 1, since the spring force of the clamp spring is detected, the clamp force can be detected directly and accurately, the clamp force can be determined normally, and the determination result can be notified, Maintenance and inspection can be performed so that the tool holder can always be securely clamped.

  According to a second aspect of the present invention, the clamp spring includes an unclamp operation portion for releasing the clamped state by the draw bar against a spring force of the clamp spring, and the detection means acts on the unclamp operation portion. The spring force of is detected.

  According to the second aspect of the present invention, the spring force of the clamp spring can be detected by using the unclamp operation portion, and it is not necessary to provide a special mechanism for detection, which can contribute to simplification of the configuration.

  According to a third aspect of the present invention, there is provided drive means for operating the unclamp operation section, and the detection means applies a load applied to the drive means when the drive means operates the unclamp operation section. The spring force is detected.

  When the unclamping operation unit is operated, a spring force by a clamp spring acts on the driving unit as a load. Since this load is detected as the spring force of the clamp spring, the spring force of the clamp spring can be easily detected.

According to a fourth aspect of the invention, the drive means is an actuator that moves the spindle head.
In the fourth aspect of the invention, since the driving means is constituted by an actuator that moves the spindle head, the spring force of the clamp spring can be detected using an existing actuator, which can contribute to simplification of the configuration. .
According to a fifth aspect of the present invention, the machine tool further includes a column that supports the spindle head so as to be movable up and down, and a column driving unit that moves the column in a direction orthogonal to each other on a horizontal plane. A load applied to the column driving means is detected as a spring force of the clamp spring.
According to the fifth aspect, the spring force of the clamp spring acting on the unclamp operation portion can always be detected during the operation of the unclamp operation portion regardless of the shape of the unclamp operation portion, so that the detection error is reduced. be able to.

  According to a sixth aspect of the present invention, when the tool is operated when the unclamping operation unit is operated, the detection operation by the detection means may be performed simultaneously, or the detection operation may not be performed, and only when the detection operation is performed. Changed the tool change speed.

In this sixth aspect, since the tool change speed becomes slow, the detection accuracy of the spring force is further improved.
The invention of claim 7 includes a main shaft rotatably provided on the main shaft head, and a draw bar which is provided on the main shaft and includes a clamp spring and clamps the tool holder on the main shaft by the spring force of the clamp spring. The computer of the numerical control device for controlling the machine tool includes a detection means for detecting the spring force of the clamp spring, a comparison means for comparing the spring force detected by the detection means with a preset reference value, and this comparison It functions as an informing means for informing the comparison result of the means.

  In the invention of claim 7, the detecting means detects the spring force of the clamp spring, the comparing means compares the spring force detected by the leather means with a preset reference value, and the notifying means notifies the comparison result. In order to notify, the effect similar to that of claim 1 is achieved.

In the invention according to claim 8, the numerical control program according to claim 7 is stored in a storage medium.
In the invention of claim 8, a ROM, a CD-ROM, a flexible disk, or the like is applicable as a storage medium. By causing the computer to execute the numerical control program stored in the storage medium, the operation similar to that of the first aspect is achieved.

  According to the present invention, the clamping force can be detected with a simple configuration and high accuracy.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This will be described with reference to FIGS. First, FIG. 1 is a longitudinal side view showing a schematic configuration of a machine tool used in this embodiment. As shown in FIG. 1, a machine tool 1 includes a column 2 erected on a base (not shown), a frame 3 comprising a box-shaped hollow casing horizontally disposed and fixed on the front surface of the column 2, A spindle head 4 is arranged in the frame 3 so as to be movable up and down, and a tool magazine 6 which can be rotated and indexed is arranged in the frame 3 via a magazine support 5.

In this configuration, a guide rail 7 is disposed vertically on the column 2, and the spindle head 4 is provided on the guide rail 7 via a sliding top 8, 8 so as to be movable up and down (Z-axis). ing. In the column 2, a rotatable ball screw 9 is provided in parallel along the guide rail 7, and this ball screw 9 is screwed and inserted into a nut 10 fixed to the back surface of the spindle head 4. The ball screw 9 is configured to be driven to rotate forward and backward by a Z-axis motor 11 disposed at the upper part of the column 2. The spindle head 4 is moved in the vertical direction along the guide rail 7 through the ball screw 9 and the nut 10 by driving the Z-axis motor 11. Therefore, the Z-axis motor 11 is composed of a servo motor, for example, and corresponds to an actuator that moves the spindle head 4.
As shown in FIG. 2, a main shaft 12 is rotatably arranged vertically inside the main shaft head 4, and the main shaft 12 is connected to a main shaft motor 13 disposed on the upper portion of the main shaft head 4. It is connected via a ring 12a and is driven to rotate by the spindle motor 13.

  The main shaft 12 is formed in a hollow shape, and a draw bar 14 is inserted therein so as to be movable in the axial direction. The draw bar 14 is urged upward by a clamp spring 15. A collet chuck 16 including a plurality of steel balls 16 a and the like is formed at the tip (lower end) of the draw bar 14. In the collect chuck 16, the draw bar 14 is moved downward against the spring force of the clamp spring 15, so that the steel ball 16a extends from the lower sliding hole 12b of the main shaft 12 to the upper part of the tool holder mounting hole 12c. It goes out to the continuous space part 12d and the chucking with respect to the pull stud 17a of the tool holder 17 is cancelled | released.

Conversely, when the draw bar 14 is moved upward from the lower position, the steel ball 16a enters the lower sliding hole 12b having a small diameter from the space portion 12d and chucks the pull stud 17a.
The draw bar 14 is pushed down by an unclamping operation unit 18 shown in FIG. 1, and when the pushing-down operation is released, the aforementioned chucking or clamping is performed by the spring force of the clamp spring 15. ing.

The unclamp operation unit 18 is for releasing the clamped state by the draw bar 14 against the spring force of the clamp spring 15, and includes an unclamp pin 19, an unclamp lever 20, and an unclamp cam 21. And the unclamping roller 22 and the Z-axis motor 11 as a driving means.
The unclamp pin 19 is fixed to the upper portion of the main shaft 12 in a protruding state in the radial direction, and both end portions of the unclamp pin 19 are elongated holes 12e in the axial direction of the main shaft 12 (this is a facing state). Project outward.

  The unclamp lever 20 is a substantially L-shaped member, and is disposed on the spindle head 4 so as to be able to swing (turn) via a support shaft 23. The tip of the shorter end 20a, which is one end of the unclamp lever 20, is formed in a bifurcated shape when seen in a plan view so that the lower surface of the tip can be engaged with the unclamp pin 19. It is configured. On the right side surface in FIG. 1 of the longer end 20b, which is the other end of the unclamp lever 20, the unclamp cam 21 made of, for example, a plate cam is fixed. The unclamp lever 20 is urged in the direction of arrow A by a spring 23a.

As shown in FIG. 4, the unclamp cam 21 has a first inclined portion 21a, a flat portion 21b, a second inclined portion 21c, and a second flat portion 21d as a cam surface 21A.
The unclamping roller 22 is fixed to the motor frame of the Z-axis motor 11 and can be slidably contacted with the cam surface 21A of the unclamping cam 21, so that the unclamping lever 20 is counteracted by this sliding contact. It rotates in the direction of arrow A and pushes the unclamp pin 19 downward. When the unclamp pin 19 is pushed down, the draw bar 14 moves in the axial direction (downward), so that the collect chuck 16 chucks the pull stud 17a of the tool holder 17 as described above. Yes. A tool 40 is attached to the tool holder 17.

  FIG. 5 shows an electrical configuration of the numerical controller 24 in the machine tool 1. The control device 25 includes a microcomputer, and includes an input / output interface 26, a CPU 28, a ROM 29, a RAM 30, axis control circuits 31, 32, 33, 34, 35, servo amplifiers 11a, 13a, 36a, 37a, differentiators 11d, 13d, 36d, 37d and current detectors 11e, 13e, 36e, 37e. The servo amplifiers 11a, 13a, 36a, and 37a are connected to the Z-axis motor 11, the main shaft motor 13, the X-axis motor 36, and the Y-axis motor 37, respectively. The axis control circuit 35 is connected to the magazine motor 38.

  The X-axis motor 36 and the Y-axis motor 37 are for moving a machining table (not shown) in the X-axis direction and the Y-axis direction. The magazine motor 38 is for rotating the tool magazine 6. The Z-axis motor 11, the main shaft motor 13, the X-axis motor 36, and the Y-axis motor 37 include encoders 11c, 13c, 36c, and 37c, respectively.

  The axis control circuits 31 to 34 receive movement command amounts from the CPU 28 and output current command values (torque command values) to the servo amplifiers 11a, 13a, 36a, and 37a. The servo amplifiers 11a, 13a, 36a, 37a receive this command and output drive currents to the motors 11, 13, 36, 37. The axis control circuits 31 to 34 receive position feedback signals from the encoders 11c, 13c, 36c, and 37c and perform position feedback control. The differentiators 11d, 13d, 36d, and 37d differentiate the position feedback signals input from the encoders 11c, 13c, 36c, and 37c, convert them into speed feedback signals, and output the speed feedback signals to the axis control circuits 31 to 34. .

  The axis control circuits 31 to 34 receive speed feedback signals from the differentiators 11d, 13d, 36d, and 37d and perform speed feedback control. The drive currents output from the servo amplifiers 11a, 13a, 36a, 37a to the motors 11, 13, 36, 37 are detected by current detectors 11e, 13e, 36e, 37e. The drive currents detected by the current detectors 11e, 13e, 36e, and 37e are fed back to the axis control circuits 31 to 34.

  The axis control circuits 31 to 34 perform current (torque) control by the fed back drive current. In general, since the drive current flowing through the motor and the load torque applied to the motor are approximately the same, in this embodiment, current detectors 11e, 13e, 36e, which detect the drive current flowing through the motor 11, 13, 36, 37, The means which can detect the load torque concerning the motor 11, 13, 36, 37 is comprised by 37e. The axis control circuit 35 receives the movement command amount from the CPU 28 and drives the magazine motor 38.

The control device 25 is connected to a display 39 as a notification unit and an operation input unit 41 including operation keys and the like.
Further, the control device 25 functions as a detecting means for detecting the spring force of the clamp spring 15 and a comparing means for comparing the spring force detected by the detecting means with a preset reference value. The spring force of the clamp spring 15 acting on the unclamp operation unit 18 is detected by the load applied to the Z-axis motor 11.
When a load is generated on the Z-axis motor 11 from the outside, a speed change occurs. This speed change is detected by a position feedback signal and a speed feedback signal. The axis control circuits 31 to 34 control the drive current in order to recover the detected speed change. Therefore, the control device 25 detects the spring force with the drive current value correlated with the load because the drive current value of the Z-axis motor 11 increases as the load of the Z-axis motor 11 increases during feedback control.

  Specifically, when the Z-axis motor 11 is rotationally driven in a predetermined direction and the spindle head 4 is raised via the ball screw 9, the first inclined portion 21a of the unclamp cam 21 is unclamped as shown in FIG. It is in sliding contact with the clamp roller 22. When the spindle head is further raised, the unclamping lever 20 rotates counterclockwise via the support shaft 23, and the short end 20a, which is one end of the unclamping lever 20, is in sliding contact with the unclamping pin 19. The clamp spring 15 is pushed down. At this time, the unclamp lever 20 receives a force Fc (restoring force of the clamp spring 15) from the clamp spring 15. By this force Fc, the unclamp lever 20 is urged clockwise around the support shaft 23 to push the unclamp roller 22 with the force Ff. As a reaction force, the amplifier lamp roller 22 pushes the unclamp lever 20 with a force Fb. The vertical component force Fa of the force Fb acts as a force for pushing down the spindle head 4, and the load on the Z-axis motor 11 increases.

  Further, when the unclamp roller 22 is in sliding contact with the first flat portion 21 b of the unclamp cam 21, the unclamp cam 21 presses the unclamp roller 22 with the force Fd by the unclamp spring 15. The unclamp cam 21 receives the reaction force Fe of the force Fd. In this case, the unclamp cam 21 presses the unclamp roller 22 only in the horizontal direction. Accordingly, the vertical component force of the reaction force Fe is zero.

  The operation of this detection means will be described with reference to FIGS. FIGS. 6 and 7 are flowcharts showing the control contents of the control device 25. In FIGS. 6 and 7, in step S1, the Z-axis motor 11 is driven to rotate in a predetermined direction, and the spindle head is connected via the ball screw 9. Raise 4 The left vertical axis in FIG. 9 indicates the drive current value, and the right vertical axis indicates the height position of the spindle head 4. The abscissa indicates the passage of time from the start of rising of the spindle head 4. The lower graph in FIG. 9 shows the change in the drive current value with the lapse of time of the Z-axis motor 11, and the upper graph shows the change in the position of the spindle head 4 with the lapse of time.

Based on the rotation of the Z-axis motor 11 in a predetermined direction, the spindle head 4 rises in the direction of arrow U in FIG. 8, and the unclamp cam 21 also rises.
In step S2, when the first inclined portion 21a of the unclamping cam 21 reaches a height position just before the unclamping roller 22 is encountered (the first height position Za in FIG. 9) ta (the spindle head 4). (Ta second has elapsed since the start of the movement) until the second flat portion 21d of the unclamp cam 21 reaches the height position (second height position Zb in FIG. 9) at the time tb (main shaft The maximum value Tmax of the drive current is stored during the period from when the head 4 starts to rise until tb seconds elapse).

  In the next step S3, the average value of the drive current value from the second height position Zb until the second flat portion 21d of the unclamp cam 21 reaches the third height position Zc in FIG. Ta is calculated and stored.

The heights Zb and Zc can be detected by the encoder 11c of the Z-axis motor 11.
In FIG. 9, the first peak M1 of the drive current value appears when the unclamp roller 22 is in sliding contact with the first inclined part 21a of the unclamp cam 21, and the next peak M2 is the second inclined part 21c. Appears when sliding.

  In step S4, the raising is completed to the tool change origin position (origin position Zd in FIG. 9). Thereafter, in step S5 in FIG. 6, the detected presence or absence of deterioration of the clamp spring 15 is determined. This determination process will be described with reference to FIG. 7 shown as a subroutine. In step P1, the difference (Tmax−Ta) between the detected maximum value Tmax and average value Ta of the drive current (Tmax−Ta) is set to the difference between the preset reference value Tb (reference value for spring deterioration determination) and the average value Ta ( Tb-Ta). When (Tmax−Ta) is larger than (Tb−Ta), it is determined that the spring force of the clamp spring 15 is normal (not deteriorated), and the process returns to step S6 in FIG. If (Tmax-Ta) is equal to or less than (Tb-Ta), the process proceeds to step P3, where it is determined that the spring force has decreased (spring deterioration), and the purpose of the spring deterioration is displayed on the display 39 ( Notification). Thereafter, the process returns to step S6 in FIG.

In this step S6, the spindle head 4 is moved forward, for example, to the machining origin and lowered.
The above-described spring force detection operation of the clamp spring 15 may be performed every time the tool is changed so that the unclamp operation unit 18 is operated by the generation of a tool change command. Or at an appropriate time by the user.

  That is, as shown in FIG. 10, when a tool change command is generated, it is determined in step Q1 whether the deterioration determination flag is on. This deterioration determination flag may be turned on automatically every time the number of tool replacements reaches a predetermined number, or the user may input a deterioration determination flag and set it on prior to operation. Alternatively, the user may input a parameter and turn on the deterioration determination flag every number of times indicated by the parameter.

  When the deterioration determination flag is on in step Q1, the process proceeds to step Q2, where the tool change speed is set to be lower than the normal speed, and in step Q3, the tool change and the spring force detection operation are executed. When the deterioration determination flag is off, the process proceeds to step Q4, the tool change speed is set to the normal speed, and tool change is executed in step Q5.

As described above, when the tool is operated in which the unclamping operation unit 18 is operated, the detection operation may be performed at the same time or the detection operation may not be performed. In the present embodiment, when the detection operation is performed. Only the tool changing speed (that is, in this embodiment, the moving speed of the spindle head 4 and hence the rotational speed of the Z-axis motor 11) is decreased.
According to this embodiment, since the spring force of the clamp spring 15 is detected, the clamp force can be detected directly and accurately, the clamp force can be determined normally, and the determination result can be notified. Thus, maintenance and inspection can be performed so that the tool holder 17 can always be securely clamped.

  Further, according to the present embodiment, the unclamp operation portion 18 for releasing the clamped state by the draw bar 14 against the spring force of the clamp spring 15 is provided, and the clamp spring acting on the unclamp operation portion 18 is provided. Since the spring force of 15 is detected, the spring force of the clamp spring 15 can be detected by using the unclamp operation portion 18, and it is not necessary to provide a special mechanism for detection, and the structure is simplified. Can contribute.

  In addition, according to the present embodiment, the load applied to the driving means for operating the unclamp operation unit 18 is detected as the spring force of the clamp spring 15. Therefore, the spring force of the clamp spring 15 is easily detected. It becomes possible.

  Further, according to the present embodiment, the driving means is constituted by the Z-axis motor 11 which is an actuator for moving the spindle head 4, so that the spring force of the clamp spring can be detected using an existing actuator, This can contribute to simplification of the configuration.

  Further, in this embodiment, when the tool is changed when the unclamp operation unit 18 is operated, there are a case where the detection operation is performed simultaneously and a case where the detection operation is not performed. Unlike the normal tool change speed, the tool change speed (that is, the moving speed of the spindle head 4 and hence the rotation speed of the Z-axis motor 11 in this embodiment) is reduced only when the detection operation is performed. The load applied to the Z-axis motor 11 can be detected well, and the accuracy of detecting the spring force is further improved.

The present invention is not limited to the above-described embodiments, and may be modified as follows.
In the above embodiment, the Z-axis motor 11 that is an actuator for moving the spindle head 4 is also configured as a driving means for operating the unclamping operation unit 18, but the actuator for moving the spindle head; A driving means for operating the unclamping operation unit, and the detection means detects the spring force of the clamp spring by a load applied to the driving means when the driving means operates the unclamping operation unit. It is good also as composition to do. In this case, the spring force of the clamp spring is directly detected by the load applied to the drive means for directly operating the unclamp operation portion. Therefore, the spring force of the clamp spring is detected using the drive means of the unclamp operation portion. This can contribute to the simplification of the configuration and improve the detection accuracy.

Further, as a means for detecting the spring force of the clamp spring 15 acting on the unclamp operation unit 18, a motor torque or a current command value (torque command value) may be detected.
Alternatively, the force exerted on the Z-axis motor 11 by the spring force of the clamp spring may be regarded as a disturbance, and the current value as a result of estimating the disturbance load torque may be detected as the spring force as the spring force detection means of the clamp spring 15. A method for estimating the disturbance load torque will be described below.

FIG. 11 is a schematic block diagram for obtaining the disturbance load torque. FIG. 11 shows a block diagram when the disturbance load torque is estimated by comparing accelerations, and only the Z-axis motor 11 is shown. Furthermore, only the blocks corresponding to those after the axis control circuit of FIG. 5 are extracted.
The differentiator 11d differentiates the output from the encoder 11c and outputs the speed to the differentiator 11e. The differentiator 11e differentiates the speed output from the differentiator 11d and outputs the acceleration to the calculation block 11g.

The calculation block 11f integrates the current command value output from the axis control circuit 31 by the parameter α (a value obtained by dividing the motor torque constant Kt by the inertia J of the Z-axis motor) and outputs the result to the calculation block 11g.
The calculation block 11 h divides the result calculated in the calculation block 11 g by the parameter α described above, and outputs the result to the axis control circuit 31. The value calculated by the calculation block 11h represents the estimated value of the disturbance load torque as a current value. This current value is used instead of the drive current value to detect the spring force.

In addition, a strain sensor or the like is disposed at an appropriate location of the unclamp operation unit 18 (for example, a joint between the end 20b of the unclamp lever 20 and the unclamp cam 21), and the spring force of the clamp spring 15 is provided by the strain sensor. May be detected.
Further, the cam surface 21A of the unclamp cam 21 may be formed by only one inclined portion. The unclamp cam 21 may be provided on the fixed side (Z-axis motor or column 2 side), and the unclamp roller 22 may be provided on the unclamp lever 20 side. Further, the notification means may be a buzzer or an audio output device.

  Further, in this embodiment, as a detecting means for detecting the spring force of the clamp spring acting on the unclamp operation portion, a vertical component force acting on the unclamp operation portion is detected by the drive current of the Z-axis motor. However, you may comprise so that the horizontal component force which acts on an unclamp operation part may be detected with the drive current of another motor.

  In this case, for example, the column 2 is configured to be movable in the left-right direction in FIG. 1, and includes motors (X-axis motor 36 and Y-axis motor 37 shown in FIG. 5) that move the column in the left-right direction. Is detected by the drive current of the X-axis motor 36 or the Y-axis motor 37 to detect the spring force of the clamp spring. This is because the column 2 tries to move by the horizontal component force, but the control device outputs a drive current to the X-axis motor 36 or the Y-axis motor 37 in order to maintain the column 2 at the current stop position. is there. The X-axis motor 36 or the Y-axis motor 37 corresponds to column driving means.

In the present invention, the drive current is detected when the spindle head 4 is raised, but the drive current (M3 portion in FIG. 9) may be detected when the spindle head 4 is lowered.
In the present invention, the deterioration of the clamp spring 15 is determined using the difference between the maximum drive current and the reference value with the average value of the drive current, but it may be determined simply by comparing the maximum drive current with the reference value. .

In the present invention, the value of the maximum drive current is set as a comparison object. For example, the drive current value after a predetermined time has elapsed since the spindle head 4 started to rise is stored, and the drive current The value may be compared with a reference value. At this time, the reference value may also be set to a smaller value than when compared with the value of the maximum drive current. Further, the value when the spindle head 4 reaches a predetermined position may be stored as the value of the drive current to be compared.
Further, since the drive current value is a value specific to each machine tool (for example, M1 ′ and M2 ′ in FIG. 9), the reference value and the like may be set accordingly.

1 is a longitudinal side view of a machine tool showing an embodiment of the present invention. Longitudinal side view of main spindle and clamp spring with tool holder installed Longitudinal side view of main spindle and clamp spring without tool holder Side view of unclamp cam and unclamp roller Block diagram showing electrical configuration Flow chart showing control contents Flow chart of spring deterioration judgment processing The figure which shows the mode of the spring force action Diagram showing changes in drive current value, etc. Flow chart for explaining low speed setting of tool change speed Block diagram for estimating disturbance load torque

Explanation of symbols

In the drawings, 1 is a machine tool, 4 is a spindle head, 11 is a Z-axis motor (actuator, drive means), 12 is a spindle, 13 is a spindle motor, 14 is a draw bar, 15 is a clamp spring, 16 is a collet chuck, 16a is Steel ball, 17 is a tool holder, 17a is a pull stud, 18 is an unclamp operation part, 19 is an unclamp pin, 20 is an unclamp lever, 21 is an unclamp cam, 22 is an unclamp roller, 24 is a numerical control device, Reference numeral 25 denotes a control device (detection means, comparison means), 31 denotes an axis control circuit, and 39 denotes a display (notification means).

Claims (8)

Numerical control for controlling a machine tool including a main shaft rotatably provided on the main shaft head, and a draw bar provided on the main shaft and having a clamp spring and clamping the tool holder to the main shaft by the spring force of the clamp spring. In the device
Detecting means for detecting a spring force of the clamp spring;
A comparison means for comparing the spring force detected by the detection means with a preset reference value;
A numerical control apparatus comprising: an informing means for informing a comparison result of the comparing means. An unclamp operation part for releasing the clamping state by the draw bar against the spring force of the clamp spring;
The numerical control apparatus according to claim 1, wherein the detection unit detects a spring force of the clamp spring that acts on the unclamp operation unit. Drive means for operating the unclamping operation unit;
The numerical control device according to claim 2, wherein the detection unit detects a load applied to the drive unit as a spring force of the clamp spring when the drive unit operates the unclamp operation unit. .   The numerical controller according to claim 3, wherein the driving unit is configured by an actuator that moves the spindle head. The machine tool includes a column that supports the spindle head so as to be movable up and down, and column driving means that moves the column in directions orthogonal to each other on a horizontal plane,
The numerical control device according to claim 2, wherein the detection unit detects a load applied to the column driving unit as a spring force of the clamp spring.   At the time of tool change in which the unclamping operation unit is operated, the detection operation by the detection means may be performed simultaneously, or the detection operation may not be performed, and the tool replacement speed is reduced only when the detection operation is performed. The numerical control device according to claim 2, wherein the numerical control device is used. Numerical control for controlling a machine tool including a main shaft rotatably provided on the main shaft head, and a draw bar provided on the main shaft and having a clamp spring and clamping the tool holder to the main shaft by the spring force of the clamp spring. Device computer,
Detecting means for detecting a spring force of the clamp spring;
A comparison means for comparing the spring force detected by the detection means with a preset reference value;
A numerical control program that functions as notifying means for notifying the comparison result of the comparing means.   A storage medium storing the numerical control program according to claim 7.

Images