JPH081405A - Device and method for detecting lost motion - Google Patents

Abstract

PURPOSE:To realize the excellent tool correction by detecting the positional error of the cutter tip caused by the fitting of the tool, the wear or the like as well as the amount of the lost motion of the driving shaft servo system. CONSTITUTION:The X-axis coordinate is detected by the surface 12a1 in the X-axis direction of a touch sensor 12, and the Z-axis coordinate is similarly detected by the surface 12c1 in the Z-axis direction to obtain the positional error of the cutter tip in the X-axis direction and Z-axis direction. Then, the X-axis is positioned by changing the positioning direction by 180 deg., two coordinate values of the Z-axis are detected by bringing the cutter tip into contact with the inclined surface 12c2 of the touch sensor 12 by the movement in the negative direction of the Z-axis to obtain the amount of the X-axis lost motion, two coordinate values of the X-axis in the different Z-axis positioning direction are similarly detected by the inclined surface 12a2 of the touch sensor 12 to obtain the amount of the Z-axis lost motion, and the sum of the positional error and the amount of the lost motion is made the correction of the tool.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting a lost motion of a machine tool such as an NC lathe, and more particularly to continuously detecting a tool edge position error amount and a lost motion amount of a drive axis servo system. The present invention relates to a lost motion detection method and device that can perform the lost motion detection.

[0002]

2. Description of the Related Art Conventionally, a tool tip position detecting device for a tool attached to a turret tool post in an NC lathe has a main shaft 502 rotatably supported by a main stock 501 of a lathe as shown in FIG. The chuck 503 is fitted to the tip, and the L-shaped turning arm 504 is attached to the side surface of the headstock 501.
Is pivotally supported. A pinion 506 is fitted to the tip of a pivot shaft 505 of the swivel arm 504, a pinion 506 is meshed with a rack 510 connected to a piston 508 of a fluid pressure cylinder 507, and the swivel arm 504 is in an upper standby position. And a detection position in front of the chuck.

A touch sensor 512 having four measuring elements respectively directed in the plus and minus directions of the X-axis and the Z-axis is attached to the tip of the turning arm 504, and the edge of the tool T is detected by the touch sensor 512. The turret tool post 511 is moved until it reaches the position, and the current position (coordinate value) at this time is compared with the offset value from the machine origin of the corresponding contact point of the touch sensor that is stored in advance to obtain the tool tip position error amount. Is the tool compensation amount.

In order to obtain higher machining accuracy, there is also a method of performing trial cutting after tool correction and correcting the tool correction amount based on the error obtained by measuring the work. FIG. 7 is a diagram showing an example of a method for measuring the X-axis lost motion amount. The test bar 514 is held on the chuck 503 so as to be concentric with the spindle 502, and the turret tool post 5 is attached.
The dial gauge 515 is attached to 11 so as to face the negative direction of the X axis.

Then, the turret tool post 511 is axially moved in the order of the trajectory A of the feed shaft shown in the figure, and the dial gauge 515 is read when the turret tool post 511 is brought into contact with the test bar 514. The X-axis lost motion amount is obtained from the difference from the reading of the dial gauge 515 when the test bar 514 is brought into contact with the test bar 514.

[0006]

The method for obtaining the tool edge position error amount and the lost motion amount described in the prior art can be obtained by separate unrelated operations, and if both are continuously obtained. It has a problem that it takes a lot of labor and time.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to continuously detect a tool edge position error amount and a lost motion amount and combine them. Another object of the present invention is to provide a lost motion detection method and apparatus that enables highly accurate machining by setting a tool correction amount.

[0008]

In order to achieve the above object, a lost motion detecting method in the present invention is a lost motion detecting method using a touch sensor of a tool edge position detecting device of a machine tool such as a lathe, Identical positioning in which the direction of X-axis positioning differs by 180 ° when the blade tip comes into contact with the X-axis of the probe head facing the Z-axis direction of the touch sensor and the blade-edge contact surface inclined with respect to the Z-axis by the movement in the Z-axis direction The two Z-axis coordinate values in the command value are detected, the X-axis lost motion amount is obtained from the difference between the two Z-axis coordinate values, and the X-axis and Z-axis of the contact point facing the X-axis direction of the touch sensor are determined. The two X-axis coordinate values at the same positioning command value different by 180 ° in the Z-axis positioning direction when the blade edge comes into contact with the blade edge contact surface inclined with respect to the X-axis direction by detecting the two X-axis coordinate values From the difference in coordinate values The amount of Z-axis lost motion is obtained.

Further, the loss motion detecting device according to the present invention is a tool edge position detecting device for detecting a tool edge position error amount by a touch sensor of a machine tool such as a lathe,
A second blade tip contact surface inclined to the X axis and the Z axis to a plurality of measuring elements having a first blade tip contact surface that is orthogonal to the X axis or the Z axis that faces the X axis and the Z axis of the touch sensor. Is provided to detect and store two coordinate values in the contact direction at the same positioning command position in which the positioning direction when the blade edge contacts the second blade edge contact surface by a movement perpendicular to the positioning direction differs by 180 °. Means for comparing the two coordinate values stored in the storage means to obtain and store the lost motion amount of the positioning direction axis due to the difference of 180 ° in the positioning direction. The error amount and the lost motion amount can be continuously detected.

The storage means detects and stores the coordinate value corresponding to the feed mode at the time of positioning, and the obtained lost motion amount corresponds to the feed mode.

[0011]

According to the first and second aspects of the present invention, the Z-direction is provided on the inclined second blade contact surface of the contact point of the touch sensor facing the Z-axis plus direction of the touch sensor.
When the blade edge comes into contact with the movement in the minus direction of the axis, the two Z-axis coordinate values that are positioned at the same X-axis positioning command value that are different in the X-axis plus direction and the X-axis minus direction are detected. Calculate the X-axis lost motion amount.

Similarly, two X-axis coordinate values whose positioning directions are different by 180 ° are detected by the inclined second blade contact surface of the probe pointing in the X-axis positive direction of the touch sensor, and the Z-axis lost motion amount is calculated from the difference. The processing accuracy is improved by obtaining

According to a third aspect of the present invention, the lost motion amounts of the X-axis and the Z-axis corresponding to the fast feed mode and the cutting feed mode at the time of positioning are obtained and stored respectively, and the lost motion amounts at the time of positioning of the machining program are dealt with. By reading the lost motion amount of the X-axis or Z-axis and obtaining the tool correction amount of the X-axis and the Z-axis, it is possible to further improve the machining accuracy.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. In the front view showing the schematic configuration of the lost motion detecting device of FIG. 1, a spindle 2 is rotatably supported by a spindle headstock 1 of an NC lathe, and a chuck 3 is concentrically fitted to the tip of the spindle 2. An L-shaped turning arm 4 is pivotally supported by a pivot shaft 5 on the side surface of the headstock 1, and a pinion 6 is fitted to the tip of the pivot shaft 5.

The pinion 6 is meshed with a rack 10 movable in the Z-axis direction connected to a piston rod 8 of a fluid pressure cylinder 7 fixed to the end surface of the headstock 1, and the X-axis is mounted on the tip of the arm 4. Four probes 12a facing the plus direction, the X axis minus direction, the Z axis plus direction, and the Z axis minus direction.
A touch sensor 12 having ~ 12d is attached.

Each of the measuring elements of the touch sensor 12 has first abutting surfaces 12a1 to 12d1 which are orthogonal to the direction in which they face, of which the measuring 12a and 12c are inclined at 45 ° with respect to the X axis and the Z axis. It also has second contact surfaces 12a2 and 12c2. The arm 4 having the touch sensor 12 at its tip is swung by the switching of the pressure fluid supplied to the fluid pressure cylinder 7, and is swung to the upper standby position and the detection position on the XZ plane passing through the spindle axis center in front of the chuck 3. The touch sensor 12 is indexed to.

On the other hand, a saddle 13 is mounted on the bed 9 so as to be movable in the Z-axis direction, and the saddle 13 is moved and positioned by a Z-axis servomotor 17 fixed to the bed 9 via a ball screw 18. A turret tool post 11 is mounted on the saddle 13 so as to be movable in the X-axis direction, and the turret tool post 11 is moved and positioned via a ball screw 16 by an X-axis servomotor 15 fixed to the saddle 13.
A tool T is detachably attached to the turret tool post 11.

The block diagram of FIG. 2 shows the servo system in the numerical controller 30 for detecting the tool edge position and setting the lost motion amount. The numerical controller 30 is roughly classified into a main processor 31, It is composed of a servo processor 32 and a power amplifier 33.

The main processor 31 has a touch sensor 1
A measurement coordinate value storage unit 34 that reads the current position of the X-axis or Z-axis of the turret tool post 11 by the touch signal 2 and stores it as a measurement coordinate value. The measured coordinate value stored in the measured coordinate value storage unit 34 is compared with the measured coordinate value by the first blade contact surface of the touch sensor 12 and the offset value from the mechanical origin of the first blade contact surface stored in advance to compare the blade position error amount. Calculation unit 35 for calculating
45 of the touch sensor 12 stored in the measurement coordinate value storage unit 34
A calculator 36 that compares two measurement coordinate values in different positioning directions by the inclined second blade contact surface to calculate the lost motion amount. A tool correction amount calculation unit 37 that calculates a tool correction amount from the error amount from the calculation unit 35 is included.

The servo processor 32 is a portion for outputting a signal to the power amplifier based on a command from the main processor.
The power amplifier 33 is a part that drives the X-axis servo motor 16 or the Z-axis servo motor 17.

Next, the operation of this embodiment will be described in the order of the flowchart of FIG. 3 with reference to the operation explanatory diagrams of FIGS. In step S1, the swivel arm 4 in the standby position is rotated to the measurement position prior to detection of the tool edge position, and the touch sensor 12 is indexed on the XZ plane passing through the center of the spindle. In step S2, the turret tool post 11 moves toward the minus side in the X-axis direction so that the tool tip of the tool T faces the X-axis of the probe 12a of the touch sensor 12.
2a1 is touched, and the touch sensor 12 stops the turret tool post 11 with a signal that detects this touch, and at this time, X
Read the axis coordinate value (current value).

Next, in step S3, the X-axis blade edge position error amount is obtained from the difference between the read X-axis coordinate value and the offset value from the mechanical origin of the first blade tip contact surface 12a1 of the probe 12a stored in advance. . In step S4, the blade tip of the tool T is moved to the minus side in the Z-axis direction of the turret tool post 11 to move the blade tip of the tool T to the contact surface 12c of the first blade tip 12c.
The turret tool post 11 is stopped by the signal that the touch sensor 12 detects the contact, and the Z-axis coordinate value at this time is read.

Next, in step S5, Z is calculated from the difference between the read Z-axis coordinate value and the offset value from the mechanical origin of the first contact surface 12c1 of the probe 12c stored in advance.
Find the amount of shaft edge error. With these operations, first, the amount of error in the position of the cutting edge of the X axis and the Z axis due to the attachment or wear of the tool T is obtained.

In step S6, the turret turret 1
1 is moved to the Z-axis direction plus side, moved away from the touch sensor 12 and moved to the X-axis direction plus side, and then moved to the X-axis direction minus side as shown by the trajectory a of the feed axis in FIG. 4 for measurement. The child 12c is positioned at a position where the inclined second blade contact surface 12c2 is present. The X-axis positioning command value at this time is X1.

Then, by moving the turret tool post 11 to the minus side in the Z-axis direction, the blade tip of the tool T is brought into contact with the inclined second blade tip contact surface 12c2 of the probe 12c, and the touch sensor 1
2 is a signal that detects this contact, stops the turret tool post 11, reads the Z-axis coordinate value of the turret tool post 11 at this time, and sets this as Z1.

In step S7, the turret turret 1
By moving 1 to the plus side in the Z-axis direction, the blade tip of the tool T is moved away from the touch sensor 12, and the turret tool post 11 is moved to the minus side in the X-axis direction. Then, as shown by the trajectory b of the feed axis in FIG. Positioning command value X by moving to the plus side in the axial direction
Position to 1.

Next, by moving the turret tool post 11 to the minus side in the Z-axis direction, the blade tip of the tool T is brought into contact with the inclined second blade tip contact surface 12c2 of the probe 12c, and the touch sensor 12 detects this contact. The turret tool post 11 is stopped by a signal, and the Z-axis coordinate value at this time is read and set as Z2.

Next, in step S8, Z1 and Z2
Find the difference between. Since the second cutting edge contact surface 12c2 has an angle of 45 ° with respect to the X axis, the difference between Z1 and Z2 is equal to the lost motion amount ΔX of the X axis.

In step S9, the turret turret 1
By moving 1 to the plus side in the X-axis direction, the blade tip of the tool T is moved away from the touch sensor 12 and moved to the plus side in the Z-axis direction, and then the tracing stylus 12a as shown in the trajectory c of the feed axis in FIG.
Is moved to the minus side in the Z-axis direction and positioned to the position where the inclined second blade contact surface 12a2 is located. The positioning command value at this time is Z3.

Then, by moving the turret tool post 11 to the minus side in the X-axis direction, the blade tip of the tool T is brought into contact with the inclined second blade tip contact surface 12a2 of the probe 12a, and the touch sensor 1
2 stops the turret tool post 11 by a signal detecting this contact, and the X-axis coordinate value at this time is read and set as X2.

Next, in step S10, the tool tip of the tool T is moved away from the touch sensor 12 by moving the turret tool post 11 in the positive direction of the X axis, and the turret tool post 11 is moved in the negative direction of the Z axis. As shown in the trajectory d of the feed axis, the positioning is performed at the positioning command value Z3 by moving in the Z axis direction plus side.

Then, by moving the turret tool post 11 toward the minus side of the X axis, the blade tip of the tool T is brought into contact with the inclined second blade tip contact surface 12a2 of the tracing stylus 12a, and the touch sensor 12 detects the contact. , The turret tool post 11 is stopped, and the X-axis coordinate value at this time is read and set as X3.

In step S11, the difference between X2 and X3 is calculated. The second cutting edge contact surface 12a2 is 45 with respect to the Z axis.
Since it has an angle of °, the difference between X1 and X2 is equal to the lost motion amount ΔZ on the Z axis.

Since the lost motion amount often shows different values depending on the feed speed at the time of positioning, at least the lost motion amount in each of the fast feed and cutting feed modes is measured and stored, and the lost motion amount is set at the time of machining. If the corresponding lost motion amount is read out in accordance with the feed mode at the time of positioning, higher precision machining becomes possible.

Further, the second blade contact surfaces 12a2 and 12c2
Need not be limited to those having an angle of 45 ° with respect to the X-axis and the Z-axis, and can be set at any angle within a range that does not hinder the detection accuracy of the probe. In this case, it is necessary to obtain the lost motion after correcting the detected coordinate value by calculation according to the angle.

[0036]

Since the present invention is configured as described above, the following effects are obtained. The first blade edge abutting surface of each of a plurality of probes facing the X-axis and Z-axis of the touch sensor detects the amount of blade edge position error due to tool attachment, wear, etc., and then the second blade edge abutment that is inclined. Lost motion amount of the positioning direction axis is detected by comparing the coordinate values of the two abutting directions under the same positioning command in which the positioning direction is 180 ° when the cutting edge abuts on the surface in a movement perpendicular to the positioning direction. Since this is done, it is not necessary to perform trial cutting as in the conventional case to measure a machining dimension error and perform tool correction again, and it is possible to perform tool correction capable of high-precision machining in a short time.

According to the third aspect, since the lost motion amount corresponds to the feed mode at the time of positioning, it is possible to reflect the difference in the lost motion amount due to the difference in feed speed such as fast feed or cutting feed in the tool compensation, High precision processing is possible.

[Brief description of drawings]

FIG. 1 is a front view of a lost motion detection device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a servo system for detecting a tool edge position and setting a lost motion amount, and a schematic configuration diagram of an essential part of the apparatus.

FIG. 3 is a flowchart showing a flow of operations of this embodiment.

FIG. 4 is an explanatory diagram of an X-axis lost motion amount measurement operation.

FIG. 5 is an explanatory diagram of a Z-axis lost motion amount measuring operation.

FIG. 6 is a front view of a conventional tool edge position detecting device.

FIG. 7 is an explanatory diagram of a conventional method for measuring lost motion of a drive axis servo system.

[Explanation of symbols]

4 Revolving Arm 11 Turret Turret 12 Touch Sensor 12a-12
d Measuring element 12a1 to 12d1 First cutting edge contact surface 12a2, 12c2 Second cutting edge contact surface 30 Numerical control device 34 Measurement coordinate value storage unit 35 Cutting edge position error amount calculation unit 36 Lost motion amount calculation unit 37 Tool correction amount calculation unit T tool

Claims (3)

[Claims] 1. A method for detecting lost motion using a touch sensor of a tool blade edge position detecting device for a machine tool such as a lathe, wherein the X-axis of a probe pointing in the Z-axis direction of the touch sensor.
The X-axis positioning direction is 180 when the blade edge comes into contact with the blade contact surface that is inclined with respect to the axis and the Z axis by the movement in the Z axis direction.
° Two Z-axis coordinate values with different same positioning command values are detected, the X-axis lost motion amount is obtained from the difference between the two Z-axis coordinate values, and the X-axis of the probe pointing in the X-axis direction of the touch sensor. And 1 in the Z-axis positioning direction when the blade edge comes into contact with the blade contact surface inclined with respect to the Z axis by the movement in the X axis direction.
A lost motion detecting method, wherein two X axis coordinate values at the same positioning command value different by 80 ° are detected and a Z axis lost motion amount is obtained from a difference between the two X axis coordinate values. 2. A tool blade edge position detecting device for detecting a tool blade edge position error amount by a touch sensor of a machine tool such as a lathe, wherein a first axis perpendicular to the X axis or the Z axis of the touch sensor and oriented in the Z axis direction. A plurality of tracing stylus having a blade tip contact surface is provided with a second blade tip contact surface that is inclined with respect to the X axis and the Z axis, and the blade tip contacts the second blade tip contact surface by a movement perpendicular to the positioning direction. A storage means is provided for detecting and storing two coordinate values of the contact direction at the same positioning command position where the positioning directions when they are different by 180 ° are compared, and the two coordinate values stored in the storage means are compared to determine the positioning direction. Means for obtaining and storing the amount of lost motion of the positioning direction axis due to the difference of 180 ° between the position and the tool edge position error amount and lost motion amount can be continuously detected. Down detection device. 3. The lost motion according to claim 2, wherein the storage means detects and stores the coordinate value corresponding to the feed mode at the time of positioning, and the obtained lost motion amount corresponds to the feed mode. Detection device.