JP2011093068A - Machine tool and displacement measurer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machine tool increased in machining accuracy by accurately measuring the distance between the center of the spindle, and the tool post even if a thermal displacement occurs. <P>SOLUTION: A displacement measurer 20 having a spindle center measuring part 22 and a tool post reference position measuring part 23 is installed on a headstock 5, and a shaft to be detected 21 is attached to the tool post 8. The spindle center measuring part 22 has gap sensors S for detecting the gaps between the outer peripheral surface of the spindle 6 and itself at least in two positions in the circumferential direction, respectively. The tool post reference position measuring part 23 has gap sensors S for detecting the gaps between the outer peripheral surface of the shaft to be detected 21 and itself at least in two positions in the circumferential direction, respectively. The machine tool includes a means 28 for acquiring the center O of the spindle and the axis of the shaft to be detected from the outputs of the gap sensors 3, and calculating the distance between the center O of the spindle and the tool post 8. The tool post reference position measuring part 23 can also be used as a sensor target. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a machine tool such as a lathe or a grinding machine, and more particularly to a machine tool having a measurement function for thermal displacement correction, and a displacement measuring instrument thereof.

  In a machine tool such as a lathe, thermal expansion and thermal deformation of a bed and other parts occur due to cutting heat and heat generated by each part accompanying machine operation. Such thermal expansion and thermal deformation lead to a decrease in processing accuracy. Some of them are equipped with a cooling device as a countermeasure. However, in order to sufficiently suppress the thermal expansion, the cooling device becomes large, and the processing accuracy cannot be ensured only by cooling. For this reason, various types have been proposed in the past in which thermal expansion is measured to correct thermal displacement such as the cutting depth of a tool.

  As an example in which a measurement means for correcting thermal displacement is provided, for example, a scale extending from a side surface of a headstock is provided, and a sensor for reading the scale is provided on a feed base such as a tool post (for example, Patent Documents). 1). There has also been proposed a method in which a scale is attached at a position corresponding to the center of the spindle on the upper surface of the spindle stock, and a sensor for reading the scale is provided on a feed table on the tool post side (for example, Patent Document 2).

Japanese Patent Laid-Open No. 3-184743 JP 2002-144191 A

  In the case where the scale is attached to the side surface of the spindle stock in Patent Document 1, the base end position of the scale is displaced by the thermal expansion of the spindle stock, so that accurate measurement is difficult. Since the scale attached at the position corresponding to the spindle center on the upper surface of the spindle stock in Patent Document 2 is located at the spindle center with respect to the advancing and retreating direction of the feedstock, even if there is thermal expansion of the spindle stock, Less affected by thermal expansion. However, depending on the shape of the bed and the headstock, the headstock may be inclined due to the difference in the amount of thermal expansion of each part. When such an inclination occurs, the scale is disposed on the upper surface of the headstock and is away from the center of the main spindle, so that the base end position of the scale is displaced. For this reason, it cannot be satisfied as a measuring means for correcting thermal displacement.

  The machining accuracy of the workpiece diameter is determined by the accuracy of the cutting edge position of the tool with respect to the spindle center. For this reason, if the distance between the center of the spindle and the tool cutting edge or the tool post can be measured with high accuracy, high-precision machining can be performed. However, none of the conventional measuring means can accurately detect the distance between the tool edge and the tool post with respect to the spindle center.

An object of the present invention is to provide a machine tool that can accurately measure the distance between the center of the spindle and the tool rest even when thermal displacement occurs, and can improve machining accuracy.
Still another object of the present invention is to enable highly accurate thermal displacement correction of tool movement by the above-described accurate measurement.
Still another object of the present invention is to accurately measure the distance between the center of the spindle and the cutting edge of the tool on the tool post so that the processing accuracy can be further improved.
Still another object of the present invention is to provide a displacement measuring instrument that can measure displacements in two-dimensional directions at two measurement sites and can accurately determine the distance between the two measurement sites. It is to be.

A machine tool according to the present invention includes a spindle stock that rotatably supports a spindle having a chuck for gripping a workpiece at a tip, and a cutter provided so as to be movable in the spindle radial direction and the spindle axis direction relative to the spindle. In a machine tool equipped with a stand,
A displacement measuring instrument comprising a spindle center measuring unit and a tool post reference position measuring unit provided on a common support is installed in a fixed position with respect to the spindle table, and the spindle center measuring unit of the displacement measuring instrument is arranged on the outer circumference of the spindle. A gap sensor for detecting a gap with respect to the outer peripheral surface of the spindle at at least two locations in the circumferential direction, and the tool post reference position measuring unit is a position of the tool post with respect to the spindle center. It is comprised by the sensor or sensor target used for the detection of this.

According to this configuration, since the gap sensor is provided in at least two places in the circumferential direction of the spindle center measuring unit of the displacement measuring device, the position of the spindle center in the two-dimensional direction can be obtained with high accuracy. Therefore, even if thermal displacement occurs in the machine tool, the position in the two-dimensional direction of the spindle center relative to the support of the displacement measuring instrument can be obtained with high accuracy. A tool post reference position measuring unit comprising a sensor or a sensor target used for detecting the position of the tool post with respect to the spindle center is provided on the support in the displacement measuring instrument having the spindle center measuring unit in which the spindle center position is obtained with high accuracy. Since the position of the tool post is detected and the position of the tool post is detected, the distance between the spindle center and the tool post can be measured with high accuracy even if thermal displacement occurs, and the processing accuracy can be improved.
As for the thermal expansion of the support of the displacement measuring device, the support is installed so that heat is not easily transmitted to the headstock of a machine tool or the like by interposing a heat insulating material or the support. By using a material having a small linear expansion coefficient for the body, the distance between the center of the spindle and the tool rest can be obtained ignoring the thermal expansion of the support. The measurement result may be corrected by measuring the temperature of the support and the thermal expansion corresponding to the temperature. In this case, unlike the thermal displacement of the machine tool, the correction is performed because the support has a simple shape. Can be easily and accurately performed.

  The machine tool of the present invention includes machine tools having the following first to fourth configurations. Any of these first to fourth machine tools has the above-described structure of the present invention as a basic structure.

The machine tool according to the first configuration of the present invention corresponds to the embodiment shown in FIG. The machine tool of the first configuration is the basic configuration of the present invention,
The tool post reference position measuring unit has, at an annular sensor support part, gap sensors that detect gaps with respect to the outer peripheral surface of the detected shaft inserted into the sensor support part in at least two places in the circumferential direction,
In the tool post, the detected shaft is provided so that it can be inserted into and removed from the tool post reference position measurement unit of the displacement measuring instrument by relative movement of the tool post with respect to the main shaft,
In a plane perpendicular to the spindle center, the spindle center obtained from the output of each gap sensor of the spindle center measurement unit and the axis of the detected axis obtained from the output of each gap sensor of the tool post reference position measurement unit Provided with spindle center / tool post distance calculation means to find the distance,
It is characterized by that.

According to this configuration, when performing displacement measurement, the tool post is moved relative to the main shaft, and the detected shaft is inserted into the tool post reference position measuring unit of the displacement measuring instrument. In this state, the spindle is measured by the gap sensor of the spindle center measuring unit, and the detected axis is measured by the tool post reference position measuring unit. The spindle center / turret distance calculation means includes a spindle center obtained from the output of each gap sensor of the spindle center measuring unit, and an axis of a detected shaft obtained from the output of each gap sensor of the tool post reference position measuring unit. The distance in the plane perpendicular to the center of the principal axis is calculated. The displacement measuring instrument is fixed in position with respect to the headstock, and the detected shaft is provided on the tool rest, so by adding a known dimension, the distance between the spindle center and any part of the tool rest, for example, the tool The distance between the cutting edge position of the tool attached to the table is obtained.
Since both the spindle center measuring unit and the tool post reference position measuring unit are provided with gap sensors in at least two places in the circumferential direction, the positions of the spindle center and the axis of the detected shaft in the two-dimensional direction can be obtained. Therefore, the distance between the spindle center and the tool post can be obtained with high accuracy with respect to thermal displacement such as expansion and contraction and tilt of the machine tool. In this way, the position of the tool post with respect to the spindle center, and hence the tool tip position, can be obtained with high precision. By using this measurement result for the thermal displacement correction for controlling the tool tip position, the processing accuracy can be improved. Can do.

The machine tool of the second configuration of the present invention corresponds to the embodiment shown in FIG. The machine tool of the second configuration is provided with a detected shaft serving as a sensor target instead of providing a sensor for the tool post reference position measuring unit of the displacement measuring instrument with respect to the machine tool of the first configuration. .
The machine tool of the second configuration is the basic configuration of the present invention,
The tool post reference position measurement unit is a detected axis serving as a sensor target, and the detected axis is parallel to the center of the main axis,
An annular sensor support portion into which the detected shaft of the displacement measuring instrument can be inserted and removed by relative movement of the tool post with respect to the main shaft, and the detected shaft inserted into the sensor support portion. A tool post mounting measuring instrument having gap sensors for detecting a gap between them in at least two places in the circumferential direction of the sensor support portion;
The spindle center that is obtained from the output of each gap sensor of the spindle center measuring unit of the displacement measuring instrument and the axis of the detected axis that is obtained from the output of each gap sensor of the tool mounting instrument is perpendicular to the spindle center. Provided spindle center / tool post distance calculation means to calculate the distance in the plane,
It is characterized by that.

  According to the machine tool of the second configuration, the tool post-mounted measuring instrument having the tool post reference position measuring unit as a detected shaft and having gap sensors for detecting the detected shaft in at least two places is provided in the tool post. Similar to the machine tool of the first configuration, even if thermal displacement occurs, the distance between the spindle center and the tool post can be measured with high accuracy, and the machining accuracy can be improved.

The machine tool having the third configuration of the present invention corresponds to the embodiment shown in FIG. 10 and the embodiment shown in FIG. According to a third configuration of the machine tool of the present invention, in the basic configuration of the present invention, the tool post reference position measuring unit is inserted into the annular sensor support unit into the sensor support unit. Having gap sensors for detecting a gap with respect to at least two places in the circumferential direction,
The bed on which the headstock and the tool post are installed is provided with a measurement relay member having the first detected shaft and either the tool post position measuring unit or the second detected shaft,
The turret is provided with the other one of the second detected shaft and the turret position measuring unit, and the turret position measuring unit is provided in a support frame portion into which the second detected shaft can be inserted and removed. Having gap sensors for detecting gaps with respect to the outer peripheral surface of the second detected shaft inserted into the support frame at at least two locations in the circumferential direction;
The spindle center obtained from the output of each gap sensor of the spindle center measuring unit, the axial position of the first detected axis obtained from the output of each gap sensor of the tool post reference position measuring unit, and the tool post position measuring unit The distance between the spindle center and the tool post to obtain the distance in the plane perpendicular to the spindle center between the spindle center and the predetermined position of the tool rest from the axial center position of the second detected shaft obtained from the output of each gap sensor Provided distance calculation means,
It is characterized by that.

In the case of this configuration, the spindle center measuring unit provided in the displacement measuring instrument fixed in position with respect to the spindle head determines the spindle center, and the first detected axis of the displacement measuring instrument and the measurement installed on the bed. The axis of the first detected shaft is obtained with the tool post reference position measuring unit of the relay member. In addition, the second detected axis is obtained by the tool post position measuring unit provided between the measurement relay member and the tool post and the second detected axis.
In the case of this configuration, the tool post position relative to the spindle axis is detected via the measurement relay member installed on the bed, but the spindle center measurement unit, the tool post reference position measurement unit, and the tool post position Since the gap sensor is provided in at least two places in the circumferential direction, the measuring unit can obtain the position in the two-dimensional direction. Therefore, the distance between the spindle center and the tool post can be obtained with high accuracy.
In addition, in this configuration, since the measurement relay member installed on the bed is used for measurement, the distance measuring instrument is provided on the tool rest with respect to the displacement measuring instrument provided at a fixed position with respect to the bed. Even in a machine tool that has a positional relationship that is difficult to detect directly, such as the length of the tool is long, the distance between the spindle center and the tool post can be obtained with high accuracy.

A machine tool having a fourth configuration according to the present invention corresponds to the embodiment shown in FIG. In the machine tool of the fourth configuration, in the machine tool of the third configuration, instead of providing the tool post reference position measuring unit in the displacement measuring instrument, the displacement measuring instrument is provided with a first detected shaft, A tool post reference position measuring unit for detecting a detected shaft is provided on the measurement relay member.
A machine tool of a fourth configuration is the basic configuration of the present invention,
The tool post reference position measurement unit is a first detected axis serving as a sensor target, and the first detected axis is parallel to the center of the main axis,
A gap sensor for detecting a gap with respect to an outer peripheral surface of the first detected shaft is provided on a circular sensor support portion in which the first detected shaft can be inserted and removed on the bed on which the spindle stock and the tool rest are installed. A measurement relay member having a measurement unit corresponding to a displacement measuring instrument having at least two positions in the direction, and either one of the tool post position measurement unit and the second detected shaft;
The turret is provided with the other one of the second detected shaft and the turret position measuring unit, and the turret position measuring unit is provided in a support frame portion into which the second detected shaft can be inserted and removed. Having gap sensors for detecting gaps with respect to the outer peripheral surface of the second detected shaft inserted into the support frame at at least two locations in the circumferential direction;
The spindle center obtained from the output of each gap sensor of the spindle center measuring unit, the axial position of the first detected axis obtained from the output of each gap sensor of the tool post reference position measuring unit, and the tool post position measuring unit The distance between the spindle center and the tool post to obtain the distance in the plane perpendicular to the spindle center between the spindle center and the predetermined position of the tool rest from the axial center position of the second detected shaft obtained from the output of each gap sensor Provided distance calculation means,
It is characterized by that.

  According to the machine tool of the fourth configuration, the measuring unit corresponding to the displacement measuring instrument is provided on the measurement relay member side. However, as with the machine tool of the third configuration, even if thermal displacement occurs, the distance between the spindle center and the tool post Can be measured with high accuracy, and the processing accuracy can be improved.

The machine tool having the fifth configuration of the present invention corresponds to the embodiment shown in FIG. According to a fifth aspect of the present invention, in the basic configuration of the present invention, the tool post reference position measurement unit is attached to the touch sensor for detecting that a tool attached to the tool post comes into contact with the tool post or the tool post. A gap sensor for detecting a distance to the tool, using a spindle center obtained from an output of each gap sensor of the spindle center measuring unit and an output of a touch sensor or a gap sensor serving as the tool post reference position measuring unit, A spindle center / tool post distance calculation means for obtaining a distance in a plane perpendicular to the spindle center between the spindle center and the cutting edge of the tool attached to the tool post is provided.
It is characterized by that.

According to the machine tool of the fifth configuration, since the touch sensor or the gap sensor for directly detecting the tool edge of the tool post is provided on the support body provided with the spindle center measuring unit, the tool edge position with respect to the spindle center is determined. Thus, it can be detected with higher accuracy.
When the touch sensor is provided, the spindle center / tool post distance calculation means outputs the output of the position detector of the mechanism that causes the tool post to move relative to the spindle base when the touch sensor is turned on. Used as a measurement value. When a gap sensor is used, the gap may be measured with the relative position of the tool post relative to the headstock as a fixed position, and the measured value may be used in the spindle center / tool post distance calculation means, or the tool post relative to the headstock. Both the output of the position detector and the detection value of the gap sensor of the mechanism for moving the relative position of the tool post and performing the relative movement of the tool post may be used.

  In the machine tool of the third or fourth configuration, in the state where the headstock has advanced to a position where the work gripped by the chuck can be processed by the tool of the tool post, the tool post reference position measuring unit is It is preferable to configure so that the first detected shaft comes out of the tool post reference position measurement unit. Thereby, it can process without each means for measurement becoming interference. Further, it is not necessary to provide a special means for avoiding interference.

  In the machine tool having each configuration according to the present invention, the spindle center measuring unit of the displacement measuring device may be positioned between the back surface of the chuck and the front surface of the head stock or inside the head stock. By disposing the displacement measuring device in this way, the displacement measuring device can be installed so that accurate measurement of the center of the spindle can be performed.

In the machine tool according to each of the configurations of the present invention, a control device is provided that moves the tool post relative to the head stock according to a command value of a movement command, and the control device is provided with the spindle for the command value. You may provide the thermal displacement correction | amendment means which correct | amends with the distance calculated | required by the center and tool post distance calculation means.
The machining accuracy of the workpiece diameter is determined by the accuracy of the cutting edge position of the tool with respect to the spindle center. As described above, if the distance between the spindle center and the tool post can be measured with high accuracy, the spindle center / tool post distance calculation means can be used for the command value for moving the tool post relative to the spindle base. By performing correction according to the obtained distance, it is possible to perform processing with high accuracy with respect to thermal displacement.
Generally, the temperature change of a machine tool during a day is not constant. When the gap sensor and spindle center / tool post distance calculation means having the above-described configuration are provided, the distance between the spindle center position and the tool post in the thermal displacement state at the time of measurement is accurately detected. Therefore, it is possible to perform highly accurate processing by performing measurement at an appropriate time and performing correction by the thermal displacement correction means after measurement.

The displacement measuring instrument of the present invention is a displacement measuring instrument that is provided with a spindle center measuring section and a tool post reference position measuring section on a common support, and is installed in a fixed position with respect to the spindle head of a machine tool, The spindle center measuring unit has a gap sensor for detecting a gap with respect to the outer circumferential surface of the spindle in at least two locations in the circumferential direction on an annular sensor support unit surrounding the outer circumference of the spindle, and the tool post reference position measuring unit Is characterized in that the annular sensor support part has gap sensors for detecting a gap with respect to the outer peripheral surface of the detected shaft inserted into the sensor support part in at least two places in the circumferential direction.
According to the displacement measuring instrument of this configuration, as described above for the machine tool of the first configuration, the position in the two-dimensional direction can be detected for each of the measurement site such as the spindle center and the measurement site such as the detected axis. Therefore, the distance between the two measurement sites can be obtained with high accuracy.

  A machine tool having a basic configuration according to the present invention is provided with a headstock rotatably supporting a spindle having a chuck for gripping a workpiece, and movable relative to the spindle in a radial direction and a spindle axis direction. In a machine tool equipped with a tool post, a displacement measuring instrument, in which a spindle center measuring unit and a tool post reference position measuring unit are provided on a common support, is installed in a fixed position with respect to the spindle base. The spindle center measuring part of the tool has a gap sensor for detecting a gap with respect to the outer circumferential surface of the spindle in at least two places in the circumferential direction on an annular sensor support part surrounding the outer circumference of the spindle, and the tool post reference position Since the measurement unit is composed of a sensor or sensor target used for detecting the position of the tool post relative to the spindle center, it can accurately measure the distance between the spindle center and the tool post even if thermal displacement occurs. And it is, thereby improving the machining accuracy.

  According to a first configuration of the machine tool of the present invention, in the machine tool of the basic configuration, the tool post reference position measurement unit is inserted into the annular sensor support unit into the sensor support unit. Gap sensors for detecting a gap with respect to the turret have at least two locations in the circumferential direction, and are inserted into and removed from the tool post reference position measurement unit of the displacement measuring instrument by the relative movement of the tool post with respect to the spindle. The detected shaft is provided as possible, and the spindle center obtained from the output of each gap sensor of the spindle center measuring unit, and the axis of the detected shaft obtained from the output of each gap sensor of the tool post reference position measuring unit, The distance between the spindle center and the tool post can be accurately measured even if thermal displacement occurs because a means for calculating the distance between the spindle center and the tool post is obtained to determine the distance in the plane perpendicular to the spindle center. , It is possible to improve the machining accuracy.

  The machine tool of the second configuration of the present invention is the machine tool of the first configuration, in which instead of providing the tool post reference position measuring unit in the displacement measuring instrument, the detected axis is provided in the displacement measuring instrument. Since the tool post reference position measurement unit that detects the tool is provided on the tool post, the distance between the spindle center and the tool post can be accurately measured even if thermal displacement occurs, as with the first configuration machine tool. Therefore, the processing accuracy can be improved.

  According to a third configuration of the machine tool of the present invention, in the machine tool having the basic configuration, the tool post reference position measurement unit is inserted into the annular sensor support unit in the sensor support unit. A gap sensor for detecting a gap with respect to the outer circumferential surface of the first spindle, a turret position measuring unit, a turret position measuring unit; A measurement relay member having either one of the second detected shafts is provided, and the other one of the second detected shaft and the tool post position measuring unit is provided on the tool post, and the tool post position measuring unit is provided. The gap sensor for detecting a gap with respect to the outer peripheral surface of the second detected shaft inserted in the support frame portion is provided in the support frame portion in which the second detected shaft can be inserted and removed. The main shaft The spindle center obtained from the output of each gap sensor of the center measurement unit, the axis position of the first detected shaft obtained from the output of each gap sensor of the tool post reference position measurement unit, and each of the tool post position measurement unit Calculate the distance between the spindle center and the tool post to obtain the distance in the plane perpendicular to the spindle center between the spindle center and the predetermined position of the tool rest from the axis position of the second detected shaft obtained from the output of the gap sensor Since the means is provided, even if thermal displacement occurs, the distance between the spindle center and the tool post can be measured with high accuracy, and the processing accuracy can be improved.

  The machine tool of the fourth configuration of the present invention is the machine tool of the third configuration, wherein instead of providing the tool post reference position measuring unit in the displacement measuring instrument, the detected axis is provided in the displacement measuring instrument. Since the tool post reference position measuring unit that detects the tool is provided on the tool post, even if thermal displacement occurs, the distance between the spindle center and the tool post can be measured with high accuracy, similar to the third machine tool. Therefore, the processing accuracy can be improved.

  According to a fifth configuration of the machine tool of the present invention, in the machine tool having the basic configuration, the tool post reference position measurement unit detects that a tool attached to the tool post is in contact with the tool, or the tool A gap sensor for detecting a distance to a tool mounted on a table, and a spindle center obtained from an output of each gap sensor of the spindle center measuring unit, and an output of a touch sensor or a gap sensor serving as the tool post reference position measuring unit. Using the spindle center / tool post distance calculation means for determining the distance in the plane perpendicular to the spindle center between the spindle center and the cutting edge of the tool attached to the tool post, even if thermal displacement occurs The distance between the spindle center and the tool edge of the tool post can be measured with high accuracy, and the processing accuracy can be improved.

  The displacement measuring instrument of the present invention is a displacement measuring instrument that is provided with a spindle center measuring section and a tool post reference position measuring section on a common support, and is installed in a fixed position with respect to the spindle head of a machine tool, The spindle center measuring unit has a gap sensor for detecting a gap with respect to the outer circumferential surface of the spindle in at least two locations in the circumferential direction on an annular sensor support unit surrounding the outer circumference of the spindle, and the tool post reference position measuring unit Has a gap sensor for detecting a gap with respect to the outer circumferential surface of the detected shaft inserted into the annular sensor support portion at at least two locations in the circumferential direction. The displacement in the two-dimensional direction can be measured, and the distance between the two measurement sites can be obtained with high accuracy.

It is explanatory drawing which combined the top view of the machine tool main body in the main axis | shaft movement type machine tool which concerns on 1st Embodiment of this invention, and the block diagram of the conceptual structure of a control apparatus. It is a fragmentary top view which shows processing operation of the machine tool. It is a top view which shows the measurement preparation operation | movement of the machine tool. It is a front view of the headstock part of the machine tool. It is a partial abbreviation side view showing a tool post and a tool of the machine tool. It is an enlarged front view of the displacement measuring device of the machine tool. It is a block diagram of the differential detection circuit and conversion means. It is a top view which shows the main axis fixed type machine tool main body in other embodiment. It is explanatory drawing which combined the top view of the machine tool main body and the block diagram of a conceptual structure of a control apparatus in the main axis | shaft movement type machine tool which concerns on other embodiment of this invention. (A) is explanatory drawing which combined the top view of the machine tool main body and the block diagram of the conceptual structure of a control apparatus in the spindle movement type machine tool which concerns on further another embodiment of this invention, (B) is the tool post It is a front view of a position measurement part. It is a top view which shows the processing operation of the machine tool main body of the machine tool. It is explanatory drawing which combined the top view of the machine tool main body and the block diagram of a conceptual structure of a control apparatus in the main axis | shaft movement type machine tool which concerns on other embodiment of this invention. It is explanatory drawing which combined the top view of the machine tool main body and the block diagram of a conceptual structure of a control apparatus in the main axis | shaft movement type machine tool which concerns on other embodiment of this invention. It is explanatory drawing which combined the top view of the machine tool main body and the block diagram of a conceptual structure of a control apparatus in the main axis | shaft movement type machine tool which concerns on other embodiment of this invention.

  A first embodiment of the present invention will be described with reference to FIGS. This machine tool is a numerically controlled machine tool, and includes a machine tool body 1 that is a machine part and a control device 2 that controls the machine tool body 1. The machine tool main body 1 is a main spindle moving type lathe. A main spindle 6 is rotatably supported on a main spindle base 5 installed on a bed 3 via a feed base 4, and a fixed support base 7 is provided on the bed 3. A turret-type tool post 8 is supported via a rotary index.

  The feed table 4 is installed on a guide 9 provided on the bed 3 so as to be movable in the left-right direction perpendicular to the center O of the main shaft 6 (X-axis direction), and is installed on the bed 3. It is driven back and forth by an X-axis moving mechanism 12 comprising a motor 10 such as a motor and a feed screw mechanism 11 that converts its rotational output into a linear motion. The feed screw mechanism 11 includes a screw shaft and a nut. As shown in FIG. 4, the headstock 5 is installed on a guide 13 provided on the feed table 4 so as to be movable in the direction of the spindle axis (Z-axis direction), and a motor 14 ( 1) and a Z-axis moving mechanism 16 comprising a feed screw mechanism 15 that converts the rotation output into a linear motion, and is driven forward and backward. The feed screw mechanism 15 includes a screw shaft and a nut. The spindle 6 is rotationally driven by a spindle motor (not shown) built in the spindle stock 5. A chuck 17 is detachably provided at the front end of the main shaft 6. The chuck 17 can grip the workpiece W (FIG. 2) by a plurality of chuck claws 17 a that move in the chuck radial direction.

  The tool post 8 is rotatable about a horizontal rotation center T along the X-axis direction on the fixed support table 7 and has a plurality of tool mounting portions 8 a arranged in the circumferential direction on the outer peripheral portion. A tool 18 such as a cutting tool or a rotary tool is attached to each tool attachment portion 8a. The tool rest 8 is pivotally indexed to a position where an arbitrary tool mounting portion 8 a faces the main shaft 6 by an indexing motor (not shown) provided on the fixed support base 7. The tool rest 8 may have a polygonal shape as shown in FIG. In FIG. 5, only the tool 18 attached to a part of the tool attaching portion 8a is shown, and the others are not shown.

In FIG. 1, the machine tool according to this embodiment is provided with a displacement measuring instrument 20 in a fixed position with respect to the head stock 5 and a detected shaft 21 on the tool rest 8 in the machine tool main body 1 having the basic structure. Is.
The detected shaft 21 has a round shaft shape and is attached to one of the tool attachment portions 8a of the tool post 8 via the holder 21a. In the state where the tool mount 8 a to which the detected shaft 21 is mounted is indexed at the angular position facing the main shaft 6, the detected shaft 21 is parallel to the main shaft 6 and is lateral to the main shaft 6. To position. The material of the shaft 21 to be detected is not particularly limited, but when a magnetic sensor is used for the displacement measuring instrument 20, it is made of a magnetic material such as steel.
The displacement measuring instrument 20 is provided with a spindle support measuring unit 22 and a tool post reference position measuring unit 23 for detecting a detected shaft 21 on a common support 24.

FIG. 6 shows an enlarged front view of the displacement measuring instrument 20. The spindle center measuring unit 22 is provided with a gap sensor S (S _{1 to} S ₆ ) for detecting a gap with respect to the outer circumferential surface of the spindle 6 on an annular sensor support 24 a surrounding the outer circumference of the spindle 6. The tool post reference position measurement unit 23 has the same configuration as the spindle center measurement unit 22, and a clearance with respect to the outer circumferential surface of the detected shaft 21 inserted into the sensor support unit 24 b is formed in the annular sensor support unit 24 b. A gap sensor (S _{1 to} S ₆ ) for detection is provided. The support 24 is plate-shaped by providing the annular sensor support portions 24a and 24b at both ends of the arm portion 24c.

  In the displacement measuring instrument 20, the center axis of the sensor support part 24 a of the spindle center measuring part 22 coincides with the spindle center O, and the tool post reference position measuring part 23 is lateral with respect to the spindle center measuring part 22. It is installed so that it may be located. As shown in FIG. 1, the spindle center measuring unit 22 is disposed between the back surface of the chuck 17 and the front surface of the headstock 5. The spindle center measuring unit 22 may be arranged inside the spindle stock 5 and the tool post reference position measuring unit 23 may be arranged so as to protrude from the spindle stock 5. The position where the displacement measuring instrument 20 is fixed may be a position where the position of the displacement measuring instrument 20 is fixed with respect to the headstock 6. In this example, the support 24 is attached to the side surface of the headstock 6. It is attached via. The support 24 is fixed to the mounting base 25 by bolts inserted through a plurality of mounting holes 24e (FIG. 6) provided in the support 24. The fixing portion provided with the mounting hole 24e in the support 24 is, for example, the arm portion 24c. In the illustrated example, the arm portion 24c is short, and attachment holes 24e are provided at positions adjacent to each other of the sensor support portions 24a and 24b.

  In addition, it is preferable to install the displacement measuring instrument 20 so that the heat of the machine tool is not easily transmitted. For example, a rubber material or a resin is provided at any position between the displacement measuring instrument 20 and the headstock 5 (FIG. 1). A heat insulating material (not shown) such as a material may be interposed. The support 24 may be made of a ceramic material or the like having a smaller linear expansion coefficient than that of the steel material.

In FIG. 6, the arrangement of the gap sensor S in the spindle center measurement unit 22 and the tool post reference position measurement unit 23 is determined by the displacement in the two-dimensional direction between the spindle center and the detected shaft axis (X axis direction: left and right direction, and Y axis). It is sufficient to provide at least two for each of the sensor support portions 24a and 24b so that detection in the direction (vertical direction) is possible, but it is preferable to provide three or more. In this example, six gap sensors S (S _{1 to} S ₆ ) that provide differential output in pairs are provided. The six gap sensors S _{1 to} S ₆ are arranged at equal intervals in the circumferential direction, and two pairs facing each other in the diametrical direction are used as a pair, and output in three axial directions shifted by 120 ° intervals. Get. Each gap sensor S is comprised by the coil etc. which detect a magnetic impedance, for example. In addition, each gap sensor S may be a capacitance type sensor. A cover 29 is provided on the inner peripheries of the sensor support portions 24 a and 24 b, and the gap sensor S is protected from protruding toward the inner diameter side of the cover 29.

  When two gap sensors S are used, for example, a position away from the center of the sensor support portions 24a and 24b in the X-axis direction and a position away from the center in the Y-axis direction orthogonal to each other are 90 degrees apart from each other. The arrangement is

  The output of each gap sensor S is input to the spindle center / tool post distance calculation means 28 in FIG. The spindle center / tool post distance calculation means 28 is provided in the control device 2 in this embodiment, but may be provided separately from the control device 2. The spindle center / tool post distance calculation means 28 calculates the positions of the center O of the spindle 6 and the center Q of the detected shaft 12 from the outputs of the gap sensors S of the spindle center measuring unit 22 and the tool post reference position measuring unit 23. This is a means for calculating the distance in a plane perpendicular to the spindle center O between the spindle center O and the specific part of the tool rest 8.

  Specifically, the spindle center / tool post distance calculating means 28 is the center of the sensor support part 24a of the spindle center measuring part 22 (more precisely, the radial center axis of the gap sensor S arranged in the radial direction in a radial arrangement). ) In the direction of two orthogonal axes (X axis, Y axis) of the center O of the spindle 6 with respect to the center of the sensor support 24b of the tool post reference position measuring unit 23 (more precisely, the gap sensor S The deviation of the axis Q of the detected shaft 21 in the direction perpendicular to the two axes (X axis, Y axis) with respect to (radiation center axis) is detected. From the detected values of these deviations, the deviation amount with respect to the reference distance (designed dimension at room temperature (distance of 20 ° C.)) between the center O of the main shaft 6 and the axis Q of the detected shaft 21 is calculated. From the amount of deviation of the distance between the center O and the axis Q, the amount of deviation of the distance between the spindle center O and any part of the tool post 8 (for example, the cutting edge of the tool 18) is obtained by an arbitrary calculation formula or the like. The amount of deviation in the distance between the center O and the axis Q may be estimated as the amount of deviation in the distance between the spindle center O and the cutting edge position of the tool 18.

  In the spindle center measuring unit 22 and the tool post reference position measuring unit 23, when three or more gap sensors S are arranged, the distance in the X-axis direction from the output of each gap sensor S to the center of each sensor support 24a, 24b. And a conversion means for converting the distance into the Y-axis direction is provided in the spindle center / inter-tool post distance calculation means 28, for example.

FIG. 7 shows an example of the converting means 26. The conversion means 26 is made of, for example, an integrated circuit, and has triaxial input terminals I _A , I _B , and I _C and X and Y biaxial output terminals O _X and O _Y. The outputs of the pair of gap sensors S (S _{1 to} S ₆ ) arranged opposite to each other are output through three differential detection circuits 27 in three axial directions whose detected differential values are 120 ° apart from each other. The detected values A, B, and C are input to the three-axis input terminals I _A , I _B , and I _C of the conversion unit 26. The detected values A, B, and C in the three-axis directions are deviation amounts in the three-axis directions of the axis of the detected shaft 21 with respect to the centers of the sensor support portions 24a and 24b of the displacement measuring instrument 20. For example, the outputs of the _two gap sensors S ₁ and S ₂ facing in the Y-axis direction are the upper side when the detected shaft 21 is shifted downward with respect to the centers of the sensor support portions 24a and 24b. The detected value of the gap sensor S ₁ is plus and the detected value of the lower gap sensor S ₂ is minus, but the sum of the plus and minus absolute values is output. Note that when the units are combined, ½ of the sum is the shift amount, but the output of the differential detection circuit 27 may be handled by the voltage value that is the sum. By detecting the differential value, the average value of the outputs of the two gap sensors S facing each other can be detected, and the detection accuracy is improved. The conversion means 26 uses the detected gap values A, B, and C in the three axial directions as distances in the X-axis direction and the outputs X and Y in the Y-axis direction with respect to the centers of the sensor support portions 24a and 24b. Output from shaft output terminals O _X and O _Y. The process of converting the input value in the three-axis direction into the output value in the two-axis direction by the conversion means 26 is performed by an arbitrary calculation method such as using the principle of the three-point method.

  The differential detection circuit 27 may be provided in the displacement measuring instrument 20. In addition to the independent integrated circuit, the converting means 26 may be operated by a computer constituting the control device 2 of FIG.

  In FIG. 1, the control device 2 includes a computer-type numerical control device, which decodes and executes each command of the machining program 31 by the arithmetic control unit 32 and gives a control command to each drive source of the machine tool main body 1. The movement command 31a in the X-axis direction of the machining program 31 is a command for moving the tool post 18 relatively to the position of the command value indicating the movement destination in the X-axis direction. Is output as a command to drive the. The movement command 31a in the X-axis direction is described as a coordinate value in the X-axis direction with the spindle center O as the origin position in this example.

  The arithmetic control unit 32 has a thermal displacement correction means 33, and in response to the command value of the movement command 31a in the X-axis direction in the machining program 31, a command value to be output to the motor 10 is between the spindle center and the tool post. Correction is performed based on the distance obtained by the distance calculation means 28. For example, the thermal displacement correction means 33 always stores the distance obtained by the spindle center / inter-tool post distance calculation means 28 and performs correction corresponding to the stored distance. In this case, when the measurement by the displacement measuring instrument 20 is performed and the calculated value of the spindle center / tool post distance calculation means 28 is updated, the correction amount of the thermal displacement correction means 33 performed thereafter changes. The correction amount by the thermal displacement correction means 33 will be described later together with the description of the measurement operation.

  The thermal displacement correction means 33 can be switched between an active state and an inactive state by a predetermined input by a switch operation or the like. The measurement operation may be performed manually by an input operation of an operation panel (not shown) attached to the control device 2, or a measurement program (not shown) is provided and the measurement program is provided. A series of measurement operations may be automatically performed by causing the control device 31 to execute. When the measurement is automatically performed, even if the measurement is performed at a set time with a timer (not shown) or the like, a series of automatic measurements may be started when the operator turns on the start switch. Anyway.

  The measurement and thermal displacement correction according to the above configuration will be described. As shown in FIG. 3, the tool post 8 is first indexed to a position where the tool mounting portion 8 a on which the shaft 21 to be measured is installed faces the spindle 6. In this state, relative movement between the tool post 8 and the spindle 6, in this embodiment, the movement of the feed base 4 and the spindle stand 5, the shaft 21 to be measured of the tool rest 8 is moved as shown in FIG. It is inserted into the sensor support part 24 b of the tool post reference position measurement part 23.

In this insertion state, the gap measurement is performed by the gap sensor S (S _{1 to} S ₆ ) in the spindle center measurement unit 22 and the tool post reference position measurement unit 23 of the displacement measuring instrument 20. The measured values of the gap sensors S are input to the spindle center / tool post distance calculation means 28, and the center O of the spindle 6 and the axis position of the detected shaft 21 are obtained, and the spindle center O and the detected shaft are obtained. The distance in the plane perpendicular to the principal axis center O between the axes Q is calculated.
Both the value of the position of the center O of the spindle 6 and the value of the position of the center Q of the detected shaft 21 obtained by the spindle center / tool post distance calculation means 28 are both in a reference state in which there is no thermal displacement, for example, a work When the machine is at room temperature (20 ° C.), it becomes zero, and if there is a thermal displacement, it becomes the value of the deviation amount of the spindle center O and the detected shaft axis Q due to the thermal displacement. The spindle center / tool post distance calculation means 28 calculates the distance between the spindle center O and the detected shaft center Q thus obtained. This distance is, for example, positions O ′ and Q ′ (not shown) that are shifted from the position of the spindle center O and the coordinate position of the detected shaft axis Q when there is no thermal displacement. And the distance between both positions O ′ and Q ′.

The calculation result of the spindle center / tool post distance calculation means 28 is stored in the spindle center / tool post distance calculation means 28 or the thermal displacement correction means 33. The thermal displacement correction means 33 executes the X-axis movement command 31a of the machining program 21 in the arithmetic control unit 32 in accordance with the distance between the spindle center and the tool post 8 thus obtained and stored as shown in FIG. When machining, the command value of the X-axis movement command 31a is corrected. This correction is, for example, correction for adding a difference between the detected distance between the spindle center O and the detected shaft axis Q and the design dimension to the command value. The thermal displacement correction means 33 has, for example, a relational setting means such as an arithmetic expression or a table for determining a correction amount for the calculation result of the spindle center / tool post distance calculation means 28, and this means is used. The command value may be corrected with a correction amount determined in advance. The relationship determined by the relationship setting means is, for example, based on the actual operation result and the like, assuming that a relationship such as a correction amount for the difference between the distance obtained by the spindle center / tool post distance calculation means 28 and the command value is determined. Also good. Thus, by correcting by the thermal displacement correction means 33, the distance R from the spindle center O to the cutting edge during processing can be corrected with high accuracy corresponding to the thermal displacement, and the processing accuracy is improved.
By measuring at a set time such as every other hour of the day, or at a set time, and updating the calculation result of the spindle center / tool post distance calculation means 28, an appropriate thermal displacement can be obtained. Correction can be made.

  According to the machine tool having this configuration, in this way, the displacement measuring instrument 20 having the spindle center measuring unit 22 and the tool post reference position measuring unit 23 is provided, and the detected shaft 21 is provided on the tool post 8 to measure the spindle center. The part 22 and the tool post reference position measuring unit 23 include at least two gap sensors S for detecting a gap with respect to the outer circumferential surface of the main shaft 6 and a gap sensor S for detecting a gap with respect to the outer circumferential surface of the detected shaft 21 in the circumferential direction. The spindle center / tool post distance calculation means 28 for obtaining the distance between the spindle center O obtained from the output of each gap sensor S and the axis Q of the detected shaft is provided, so that even if thermal displacement occurs, the spindle The distance between the center and the tool rest 8 can be measured with high accuracy, and the processing accuracy can be improved by correcting the thermal displacement.

  In addition, although the said embodiment demonstrated about the case where it applied to a spindle moving type | mold lathe, this invention can also be applied to the turret movement type lathe shown, for example in FIG. In the machine tool main body 1 </ b> A composed of a turret movement type lathe in FIG. 1, the headstock 5 </ b> A is fixedly installed on the bed 3. The turret-type tool rest 8A is installed on the bed 3 so as to be movable in two orthogonal axes (X-axis and Z-axis) via the lower feed base 7A and the upper feed base 7B. The lower feed base 7A is movable in the X-axis direction on the guide 9A of the bed 3, and the upper feed base 7B is installed so as to be movable in the Z-axis direction on the lower feed base 7A. The lower feed base 7A and the lower feed base 7A are driven forward and backward by moving mechanisms 12A and 16A of respective axes including a motor and a feed screw mechanism. The tool post 8A has a plurality of tool attachment portions 8Aa on the outer periphery, and the detected shaft 21 having the above-described configuration is attached to one of them. Other configurations and effects are the same as those of the embodiment shown in FIGS.

  FIG. 9 shows still another embodiment of the present invention. In this embodiment, in the embodiment shown in FIGS. 1 to 7, the tool post reference position measuring unit of the displacement measuring device 20 is used as a detected shaft 21 serving as a sensor target, and the tool post mounting measuring device 30 is provided on the tool post 8. It is provided. The detected shaft 21 is provided on the support 24 of the displacement measuring instrument 20. The tool rest mounting measuring instrument 30 is attached to one of the tool attachment portions 8 a of the tool rest 8 via the holder 41. The axis of the detected shaft 21 and the tool post reference position measuring unit 23 are parallel to the center O of the main shaft 6. The tool post mounting measuring instrument 30 has the same configuration as the tool post reference position measuring unit 23 in the first embodiment shown in FIGS. 1 to 7. However, an annular sensor support frame for attaching each sensor S of the tool rest mounting measuring instrument 30 is provided in the holder 41.

  Even in such a configuration, as in the first embodiment, even if thermal displacement occurs, the distance between the spindle center O and the tool rest 8 can be measured with high accuracy, and the processing accuracy is improved. be able to. Other configurations and effects are the same as those of the first embodiment.

  10 and 11 show still another embodiment of the present invention. This embodiment is the same as the embodiment shown in FIGS. 1 to 7 between the tool post reference position measuring unit 23 of the displacement measuring instrument 20 installed on the head stock 5 and the detected shaft attached to the tool post 8. Is measured through a measurement relay member 42 installed on the bed 3. The displacement measuring instrument 20 has the same configuration as that described in the first embodiment, and is installed on the head stock 5 similarly to the first embodiment. When the measurement relay member 42 installed on the bed 3 is interposed as in this embodiment, the machine tool main body 1 needs to be a spindle movement type in which the spindle stock 5 moves at least back and forth.

  The measurement relay member 42 has a U-shaped relay member frame 43 with a planar shape fixed to the bed 3 via a mounting base 44 at the center, and the first detected shaft 21 </ b> A is connected to both ends of the relay member frame 43. The tool post position measuring unit 45 is provided. It is preferable to interpose a heat insulating material (not shown) that blocks heat conduction between the relay member frame 43 and the bed 3. The first detected shaft 21 </ b> A is an axis that is inserted into the tool post reference position measurement unit 23 of the displacement measuring instrument 20 and causes the tool post reference position measurement unit 23 to detect the axis. The first detected shaft 21A is provided in parallel with the main shaft center O, is installed on the back side of the displacement measuring instrument 20, and the main shaft base 5 moves backward as shown in FIG. 21 </ b> A is inserted into the tool post reference position measurement unit 23.

  The tool post position measuring unit 45 is a measuring unit that detects a second detected shaft 21 </ b> B that is a detected shaft attached to the tool post 8. The second detected shaft 21B is installed on the tool post 8 in the same manner as the detected shaft 21 of the first embodiment. The axis of the first detected shaft 21A and the center of the tool post position measuring unit 45 are preferably installed on the same straight line, but may be at different positions.

  As shown in FIG. 10 (B), the tool post position measuring unit 45 is inserted into the support frame portion 46 into which the second detected shaft 21B can be inserted and removed. Gap sensors S for detecting a gap with respect to the outer peripheral surface of the detected shaft 21B are provided at at least two locations in the circumferential direction. The arrangement of the gap sensor S of the tool post position measuring unit 45 is the same as that of the spindle center measuring unit 22 and the tool post reference position measuring unit 23, but the support frame unit 46 has two in the circumferential direction corresponding to the diameter direction. In this example, the detected shaft passage openings 46a and 46b are provided at the upper and lower portions, and the second detected shaft 21B passes through the detected shaft passage openings 46a and 46b when the tool post 8 is turned. It is possible to pass through the portion 46. When the tool rest 8 is a movable type, the support frame portion 46 does not need to be provided with the detected shaft passing openings 46a and 46b, and may be an annular shape.

  The second detected shaft 21B is attached to the tool post 8 via the holder 48, but the holder 48 may also serve as a tool holder for attaching the tool 18.

  The spindle center / tool post distance calculation means 28 is a first spindle target obtained from the spindle center obtained from the output of each gap sensor S of the spindle center measurement unit 22 and the output of each gap sensor S of the tool post reference position measurement unit 23. From the axial center position of the detection shaft 21A and the axial center position of the second detected shaft 21B obtained from the output of each gap sensor S of the tool post position measuring unit 45, the spindle center O and the predetermined position of the tool post 8 are determined. The distance in the plane perpendicular to the principal axis center O is determined.

  In this embodiment, the measurement is performed via the measurement relay member 42, but the distance between the spindle center O and the tool post 8 is accurately measured even if thermal displacement occurs as in the first embodiment. Therefore, it is possible to improve the processing accuracy. In the case of this embodiment, as shown in FIG. 11, in a state where the headstock 5 has advanced to a position where the workpiece W gripped by the chuck 17 can be processed by the tool 18 of the tool post 8, the tool post reference position measuring unit 23. Is the position from which the first detected shaft 21A has come off. Further, in the case of this configuration, since the measurement relay member 42 installed on the bed 3 is used for the measurement, the means provided on the tool post 8 with respect to the displacement measuring instrument 20 provided to fix the position with respect to the bed 3 is used. Even in a machine tool having a positional relationship that is difficult to detect directly, such as the distance between the two becomes long, the distance between the spindle center O and the tool rest 8 can be obtained with high accuracy. Other configurations and effects are the same as those of the first embodiment.

  FIG. 12 shows still another embodiment of the present invention. In this embodiment, in the embodiment shown in FIGS. 10 and 11, instead of providing the tool post position measuring unit 45 in the measurement relay member 42, the tool post position measuring unit 45 is provided in the tool post 8, and the second The shaft 21B to be detected is provided on the measurement relay member 42.

  Even when configured in this manner, the distance between the spindle center O and the tool post 8 can be measured with high accuracy even if thermal displacement occurs, as in the above embodiments, and the processing accuracy can be improved. Can do. Other configurations and effects are the same as those of the embodiment shown in FIGS.

  FIG. 13 shows still another embodiment of the present invention. In this embodiment, in the embodiment shown in FIGS. 10 and 11, instead of providing the tool post reference position measurement unit 23 in the displacement measuring instrument 20, the first detected shaft 21 </ b> A is provided and the measurement relay member 42 is displaced. A measuring instrument corresponding measuring unit 40 is provided.

Even when configured in this manner, the distance between the spindle center O and the tool post 8 can be measured with high accuracy even if thermal displacement occurs, as in the above embodiments, and the processing accuracy can be improved. Can do. Other configurations and effects are the same as those of the embodiment shown in FIGS.
In this embodiment, as a modification, the measurement relay member 42 may be provided with the second detected shaft 21 </ b> B and the tool post 8 may be provided with the tool post position measuring unit 45, as in the example shown in FIG. 12. good.

  FIG. 14 shows still another embodiment of the present invention. In this embodiment, in the embodiment shown in FIG. 1, the tool rest reference position measurement unit of the displacement measuring instrument 20 is provided with a touch sensor 23B on the support 24 instead of having the gap sensor S. is there. The touch sensor 23B is a sensor that is turned on when an object comes into contact with the contact detection surface 23Ba, and the tool 18 that is indexed at the machining position facing the spindle 6 of the tool post 8 can contact the contact detection surface 23Ba. Is provided. The contact detection surface 23Ba is positioned on a horizontal line orthogonal to the center O of the main shaft 6. In the spindle center / tool post distance calculation means 28, the touch sensor 23B turns on the position detection value of the position detector 10a such as a pulse coder or encoder provided in the motor 10 for moving the spindle base 5 in the X-axis direction. Sometimes read and store the value as the cutting edge position of the tool 18. The difference between the stored cutting edge position and the position of the spindle center O obtained from each gap sensor S of the spindle center measuring unit 22 of the displacement measuring device 20 is calculated as the distance between the spindle center and the tool cutting edge.

In the case of this embodiment, the position of the cutting edge is directly detected by the touch sensor 23B provided in the displacement measuring device 20 having the spindle center measuring unit 22, and therefore the distance between the spindle center and the tool cutting edge is measured with higher accuracy. be able to.
Other configurations in this embodiment are the same as those in the first embodiment shown in FIG.

  In the embodiment of FIG. 14, a gap sensor (not shown) may be provided as a tool post reference position measurement unit of the displacement measuring instrument 20 instead of the touch sensor 23 </ b> B. This gap sensor also positions the sensor center on a horizontal line orthogonal to the center O of the spindle 6 so that the position of the cutting edge of the tool 18 of the tool post 8 indexed at the machining position facing the spindle 6 can be detected. . When the gap sensor is provided, the headstock 6 at the time of measurement determines the relative position with the tool post 8, and the spindle center / tool post distance calculation means 28 is in a state where the tool tip is in the determined position. The position of the cutting edge may be obtained by reading the gap between the position of the tool 10 and the output of the position detector 10a of the motor 10 for moving the relative position of the tool rest 8 relative to the headstock 5 and moving the tool rest 8 relative to the headstock 5. And the detection value of the gap sensor may be used.

DESCRIPTION OF SYMBOLS 1,1A ... Machine tool main body 2 ... Control apparatus 3 ... Bed 4 ... Feed stand 5, 5A ... Spindle base 6 ... Spindle 7 ... Fixed support stand 8, 8A ... Tool post 8a, 8Aa ... Tool mounting part 17 ... Chuck 18 ... Tool 20 ... Displacement measuring instrument 21 ... Axis to be detected (tool post reference position measuring unit)
21A ... 1st axis to be detected (tool post reference position measuring unit)
21B ... Second detected shaft 22 ... Spindle center measurement unit 23 ... Tool post reference position measurement unit 23B ... Touch sensor 24 ... Supports 24a, 24b ... Sensor support unit 26 ... Conversion means 27 ... Differential detection circuit 28 ... Spindle Center / tool post distance calculation means 30 ... Turret mounting instrument 31 ... Machining program 31a ... Movement command 32 ... Calculation control part 33 ... Thermal displacement correction means 40 ... Displacement measuring instrument corresponding detection part 42 ... Measurement relay member 43 ... Relay Member frame 45 ... Turret position measurement unit 46 ... Support frame O ... Center Q of spindle ... Center axis S, S _{1 to} S _{6 of} detected shaft Gap sensor

Claims (10)

A machine tool comprising a headstock that rotatably supports a spindle having a chuck for gripping a workpiece at a tip, and a tool rest that is movable relative to the spindle in a radial direction of the spindle and in the direction of the spindle axis. In
A displacement measuring instrument, which is provided with a spindle center measuring unit and a tool post reference position measuring unit on a common support, is installed in a fixed position with respect to the spindle table,
The spindle center measuring unit of the displacement measuring instrument has a gap sensor for detecting a gap with respect to the outer circumferential surface of the spindle at at least two locations in the circumferential direction on an annular sensor support that surrounds the outer circumference of the spindle.
The tool post reference position measuring unit is a machine tool configured with a sensor or a sensor target used for detecting the position of the tool post with respect to the spindle center. The tool post reference position measuring unit has, at an annular sensor support part, gap sensors that detect gaps with respect to the outer peripheral surface of the detected shaft inserted into the sensor support part in at least two places in the circumferential direction,
In the tool post, the detected shaft is provided so that it can be inserted into and removed from the tool post reference position measurement unit of the displacement measuring instrument by relative movement of the tool post with respect to the main shaft,
In a plane perpendicular to the spindle center, the spindle center obtained from the output of each gap sensor of the spindle center measurement unit and the axis of the detected axis obtained from the output of each gap sensor of the tool post reference position measurement unit Provided with spindle center / tool post distance calculation means to find the distance,
The machine tool according to claim 1. The tool post reference position measurement unit is a detected axis serving as a sensor target, and the detected axis is parallel to the center of the main axis,
An annular sensor support portion into which the detected shaft of the displacement measuring instrument can be inserted and removed by relative movement of the tool post with respect to the main shaft, and the detected shaft inserted into the sensor support portion. A tool post mounting measuring instrument having gap sensors for detecting a gap between them in at least two places in the circumferential direction of the sensor support portion;
The spindle center that is obtained from the output of each gap sensor of the spindle center measuring unit of the displacement measuring instrument and the axis of the detected axis that is obtained from the output of each gap sensor of the tool mounting instrument is perpendicular to the spindle center. Provided spindle center / tool post distance calculation means to calculate the distance in the plane,
The machine tool according to claim 1. The tool post reference position measuring unit includes at least two gap sensors in the circumferential direction for detecting a gap with respect to the outer circumferential surface of the first detected shaft inserted into the annular sensor support unit. Have
The bed on which the headstock and the tool post are installed is provided with a measurement relay member having the first detected shaft and either the tool post position measuring unit or the second detected shaft,
The turret is provided with the other one of the second detected shaft and the turret position measuring unit, and the turret position measuring unit is provided in a support frame portion into which the second detected shaft can be inserted and removed. Having gap sensors for detecting gaps with respect to the outer peripheral surface of the second detected shaft inserted into the support frame at at least two locations in the circumferential direction;
The spindle center obtained from the output of each gap sensor of the spindle center measuring unit, the axial position of the first detected axis obtained from the output of each gap sensor of the tool post reference position measuring unit, and the tool post position measuring unit The distance between the spindle center and the tool post to obtain the distance in the plane perpendicular to the spindle center between the spindle center and the predetermined position of the tool rest from the axial center position of the second detected shaft obtained from the output of each gap sensor Provided distance calculation means,
The machine tool according to claim 1. The tool post reference position measurement unit is a first detected axis serving as a sensor target, and the first detected axis is parallel to the center of the main axis,
A gap sensor for detecting a gap with respect to an outer peripheral surface of the first detected shaft is provided on a circular sensor support portion in which the first detected shaft can be inserted and removed on the bed on which the spindle stock and the tool rest are installed. A measurement relay member having a measurement unit corresponding to a displacement measuring instrument having at least two positions in the direction, and either one of the tool post position measurement unit and the second detected shaft;
The turret is provided with the other one of the second detected shaft and the turret position measuring unit, and the turret position measuring unit is provided in a support frame portion into which the second detected shaft can be inserted and removed. Having gap sensors for detecting gaps with respect to the outer peripheral surface of the second detected shaft inserted into the support frame at at least two locations in the circumferential direction;
The spindle center obtained from the output of each gap sensor of the spindle center measuring unit, the axial position of the first detected axis obtained from the output of each gap sensor of the tool post reference position measuring unit, and the tool post position measuring unit The distance between the spindle center and the tool post to obtain the distance in the plane perpendicular to the spindle center between the spindle center and the predetermined position of the tool rest from the axial center position of the second detected shaft obtained from the output of each gap sensor Provided distance calculation means,
The machine tool according to claim 1. The tool post reference position measurement unit is a touch sensor that detects that a tool attached to the tool post comes into contact with the tool post or a gap sensor that detects a distance to the tool attached to the tool post, and the spindle center measurement The spindle center between the spindle center obtained from the output of each gap sensor of the tool and the spindle center and the tool tip attached to the tool rest using the output of the touch sensor or gap sensor serving as the tool rest reference position measuring section. The spindle center / tool post distance calculation means for calculating the distance in the plane perpendicular to the center is provided.
The machine tool according to claim 1.   In a state where the headstock has advanced to a position where the work gripped by the chuck can be processed by the tool of the tool post, the tool post reference position measurement unit is configured to transfer the first workpiece to the tool post reference position measurement unit. The machine tool according to claim 4 or 5, wherein the detection shaft is at a position where it has come out.   The machine tool according to any one of claims 1 to 7, wherein the spindle center measuring unit of the displacement measuring instrument is located between a back surface of the chuck and a front surface of the head stock or within the head stock.   A control device for moving the tool post relative to the head stock according to a command value of a movement command is provided, and the spindle center / tool post distance calculation means obtains the command value for the control device. The machine tool according to any one of claims 1 to 8, further comprising a thermal displacement correction unit that performs correction according to a distance. Displacement measuring instrument that is provided with a spindle center measuring unit and a tool post reference position measuring unit on a common support, and is installed in a fixed position with respect to the spindle base of a machine tool,
The spindle center measuring unit has a gap sensor for detecting a gap with respect to the outer circumferential surface of the spindle in at least two locations in the circumferential direction on an annular sensor support unit surrounding the outer circumference of the spindle, and the tool post reference position measuring unit Is a displacement measuring instrument having gap sensors for detecting gaps with respect to the outer peripheral surface of the detected shaft inserted into the sensor support portion at least at two locations in the circumferential direction.

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