WO2011052441A1 - Machine tool and displacement measuring instrument - Google Patents

Abstract

A displacement measuring instrument (20) comprising a main shaft center measuring section (22) and a blade block reference position measuring section (23) is installed on a main shaft block (5), and a blade block (8) is provided with a shaft to be detected (21). The main shaft center measuring section (22) comprises gap sensors (S) in a minimum of two circumferential positions, which detect gaps with respect to the peripheral surface of a main shaft (6). The blade block reference position measuring section (23) comprises gap sensors (S) in a minimum of two circumferential positions, which detect gaps with respect to the peripheral surface of the shaft to be detected (21). A means (28) is provided for obtaining a main shaft center (O) and the center of the shaft to be detected, on the basis of the outputs of the gap sensors (S), and for calculating the distance between the main shaft center (O) and the blade block (8). The blade block reference position measuring section (23) may be made to serve as a sensor target.

Description

Machine tools and displacement measuring instruments Related applications

This application claims the priority of Japanese Patent Application No. 2009-251716 filed on Nov. 2, 2009, which is incorporated herein by reference in its entirety.

The present invention relates to a machine tool such as a lathe or a grinder, particularly 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 the bed and other parts occur due to cutting heat and heat generated by each part due to 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 a 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 tool tip position relative 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.
Another object of the present invention is to enable highly accurate thermal displacement correction for 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. A machine tool with a table,
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 with the sensor or sensor target used for detection.

According to this configuration, since the gap sensor is provided in at least two places in the circumferential direction, the position of the spindle center measuring part of the displacement measuring device can be obtained with high accuracy in the two-dimensional direction. 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 spindle center 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 the machine tools of the following first to fifth aspects. Each of the machine tools according to the first to fourth aspects includes the above-described configuration of the present invention as a basic configuration.

The machine tool according to the first aspect of the present invention corresponds to the embodiment shown in FIG. In the machine tool of the first aspect, in the basic configuration of the present invention,
The tool post reference position measuring unit has the gap sensor for detecting a gap with respect to the outer peripheral surface of the shaft to be detected inserted into the annular sensor support unit in at least two places in the circumferential direction. And
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 Means for calculating the distance between the spindle center and the tool post for obtaining the distance are provided.

According to this aspect, 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 measurement unit and the tool post reference position measurement unit are provided with gap sensors in at least two locations 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 according to the second aspect of the present invention corresponds to the embodiment shown in FIG. The machine tool according to the second aspect is a machine tool according to the first aspect, in which a detected shaft serving as a sensor target is provided instead of providing a sensor for the tool post reference position measuring unit of the displacement measuring instrument. .

A machine tool according to a second aspect is the basic configuration of the 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 mounted measuring instrument having the gap sensor for detecting a gap between the sensor support portions in at least two locations in the circumferential direction;
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. Means for calculating the distance between the spindle center and the tool post for obtaining the in-plane distance is provided.

According to the machine tool of the second aspect, the tool post reference position measuring unit is a detected shaft, and the tool post mounted measuring instrument having the gap sensor for detecting the detected shaft is provided in at least two locations. Similar to the machine tool of the first aspect, 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 according to the third aspect of the present invention corresponds to the embodiment shown in FIG. 10 and the embodiment shown in FIG. According to a third aspect of the present invention, in the basic configuration of the present invention, the tool post reference position measurement unit is inserted into the annular sensor support unit into the sensor support unit. The gap sensor for detecting a gap with respect to the surface has 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 measurement unit,
The tool post position measuring unit includes a gap sensor for detecting a gap with respect to an outer peripheral surface of the second detected shaft inserted in the support frame portion in a support frame portion in which the second detected shaft can be inserted and removed. Have at least two places 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 A distance calculation means is provided.

In the case of this third aspect, 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 is installed on the first detected axis of the displacement measuring instrument and the bed. The axis center of the first detected shaft is obtained by the tool post reference position measuring unit of the measured 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 third aspect, the tool post position with respect to the spindle axis is detected via the measurement relay member installed on the bed, but the spindle center measuring unit, the tool post reference position measuring unit, and Since the tool rest position measuring unit is provided with at least two gap sensors in the circumferential direction, the position 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.

Further, in the case of this third aspect, since the measurement relay member installed on the bed is used for the measurement, the means provided on the tool post for the displacement measuring instrument provided to fix the position with respect to the bed, Even in a machine tool having a positional relationship that is difficult to detect directly, such as the distance between the two becomes longer, the distance between the spindle center and the tool post can be obtained with high accuracy.

The machine tool according to the fourth aspect of the present invention corresponds to the embodiment shown in FIG. The machine tool according to the fourth aspect is the machine tool according to the third aspect, wherein 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 according to a fourth aspect is the basic configuration of the 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,
The gap sensor for detecting a gap with respect to the outer peripheral surface of the first detected shaft is provided on the annular sensor support portion into 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 displacement measuring instrument corresponding measuring unit having at least two places in the circumferential direction, and any one of the tool post position measuring unit and the second detected shaft;
The turret is provided with the other one of the second detected shaft and the turret position measurement unit,
The tool post position measuring unit detects a gap with respect to an outer peripheral surface of the second detected shaft inserted in the support frame portion in a support frame portion in which the second detected shaft can be inserted and removed. In at least two places 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 A distance calculation means is provided.

According to the machine tool of the fourth aspect, the measuring unit corresponding to the displacement measuring instrument is provided on the measurement relay member side. However, similarly to the machine tool of the third aspect, 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 according to the fifth aspect of the present invention corresponds to the embodiment shown in FIG. According to a fifth aspect of the machine tool of the invention, in the basic configuration of the 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, Means for calculating the distance between the center of the spindle and the tool post for obtaining the distance in the plane perpendicular to the center of the spindle between the center of the spindle and the cutting edge of the tool attached to the tool post is provided.

According to the machine tool of the fifth aspect, since the touch sensor or the gap sensor for directly detecting the tool tip of the tool post is provided on the support body provided with the spindle center measurement unit, the tool tip 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 aspect, 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 of the present invention, the spindle center measuring unit of the displacement measuring device may be located between the back surface of the chuck and the front surface of the headstock or inside the headstock. 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 the present invention, a control device is provided for moving the tool post relative to the head stock according to a command value of a movement command, and the control device is provided between the spindle center and the tool post with respect to the command value. You may provide the thermal displacement correction | amendment means which correct | amends with the distance which the distance calculation means calculated | required.

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 Has at least two gap sensors in the circumferential direction for detecting a gap with respect to the outer peripheral surface of the detected shaft inserted into the annular sensor support portion.
According to the displacement measuring instrument having this configuration, the position in the two-dimensional direction can be detected for each of the measurement site such as the center of the spindle and the measurement site such as the detected axis, as described above for the machine tool of the first aspect. Therefore, the distance between the two measurement sites can be obtained with high accuracy.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same part number in a plurality of drawings indicates the same part.

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 2nd Embodiment. It is explanatory drawing which combined the top view of the machine tool main body in the spindle movement type machine tool which concerns on 3rd Embodiment of this invention, and the block diagram of the conceptual structure of a control apparatus. (A) is explanatory drawing which combined the top view of the machine tool main body and block diagram of the conceptual structure of a control apparatus in the spindle movement type machine tool which concerns on 4th 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 in the main axis | shaft movement type machine tool which concerns on 5th Embodiment of this invention, and the block diagram of the conceptual structure of a control apparatus. 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 6th Embodiment of this invention, and the block diagram of the conceptual structure of a control apparatus. 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 7th Embodiment of this invention, and the block diagram of the conceptual structure of a control apparatus.

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 rest 8 is rotatable about a horizontal rotation center T along the X-axis direction on the fixed support base 7, and has a plurality of tool attachment portions 8a 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 an angular position where the tool mount 8 a is opposed to the main shaft 6, the detected shaft 21 is parallel to the main shaft 6, and on the side of 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 gap sensor S of the spindle center measurement unit 22 and the tool post reference position measurement unit 23 is arranged in a two-dimensional direction (X axis direction: left and right direction, and Y axis) of the spindle center and the axis of the detected shaft. It is sufficient to provide at least two for each of the sensor support portions 24a and 24b so that detection in the axial 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 outputs one by one 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 three-axis input terminals I _A , I _B , and I _C and X and Y two-axis output terminals OX and OY. The outputs of the pair of gap sensors S (S ₁ to S ₆ ) arranged opposite to each other are transmitted 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.

Note that 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 is 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 inserted state, gap measurement is performed by the gap sensor S (S ₁ to S ₆ ) in the spindle center measuring unit 22 and the tool post reference position measuring 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 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.), the value is zero, and if there is a thermal displacement, the value is the amount of deviation between the spindle center O and the axis Q of the detected shaft 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 ′ (see FIG. 5) that are shifted by the detected deviation amounts with respect to the position of the main axis O when there is no thermal displacement and the coordinate position of the axis Q of the detected axis. (Not shown) and the distance between the two 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 the difference between the detected distance between the spindle center O and the axis Q of the detected shaft 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 lathe, this invention can also be applied to the tool post moving type lathe of 2nd Embodiment 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 a third 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.

FIGS. 10A, 10B, and 11 show a fourth 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 spindle center O, is installed on the back side of the displacement measuring instrument 20, and the spindle head 5 moves backward as shown in FIG. The detected shaft 21 </ b> A is inserted into the tool post reference position measuring unit 23.

The tool post position measuring unit 45 is a measuring unit that detects the second detected shaft 21 </ b> B that is the 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 unit 46 in the support frame unit 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 mounting of the second detected shaft 21B to the tool post 8 is performed via the holder 48, but the holder 48 may also be used as a tool holder for mounting 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 a fifth embodiment of the present invention. In this embodiment, instead of providing the tool post position measuring unit 45 on the measurement relay member 42 in the embodiments shown in FIGS. 10A, 10B, and 11, the tool post position measuring unit 45 on the tool post 8 is used. And the second detection shaft 21B 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. 10A and 10B and FIG.

FIG. 13 shows a sixth embodiment of the present invention. In this embodiment, in the embodiment shown in FIGS. 10A, 10B, and 11, instead of providing the tool post reference position measuring unit 23 in the displacement measuring instrument 20, the first detected shaft 21A is provided. The measurement relay member 42 is provided with a displacement measuring instrument corresponding measuring unit 40.

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. 10A and 10B and FIG.
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 a seventh 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 in contact with the contact detection surface 23Ba, and the cutting edge of 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 the tool post reference position measuring unit of the displacement measuring instrument 20 instead of the touch sensor 23B. 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.

As described above, the preferred embodiments of the present invention have been described with reference to the drawings, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention. Therefore, such a thing is also included in the scope of the present invention.

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 Detected shaft (cutlery Stand reference position measurement unit)
21A First detected axis (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 mounted measuring instrument 31 Processing program 31a Movement command 32 Calculation control unit 33 Thermal displacement correction means 40 Displacement measuring instrument corresponding detection unit 42 Measurement relay member 43 Relay member frame 45 Tool post position measuring unit 46 Support frame portion O Center Q of spindle Center axis S, S ₁ to S ₆ gap sensor of detected shaft

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. Because
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 the gap sensor for detecting a gap with respect to the outer peripheral surface of the shaft to be detected inserted into the annular sensor support unit in at least two places in the circumferential direction. And
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 mounted measuring instrument having the gap sensor for detecting a gap between the sensor support portions in at least two locations in the circumferential direction;
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 detects at least 2 in the circumferential direction of the gap sensor that detects a gap with respect to the outer peripheral surface of the first detected shaft that is inserted into the annular sensor support unit. In place,
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 measurement unit,
The tool post position measuring unit includes a gap sensor for detecting a gap with respect to an outer peripheral surface of the second detected shaft inserted in the support frame portion in a support frame portion in which the second detected shaft can be inserted and removed. Have at least two places 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,
The gap sensor for detecting a gap with respect to the outer peripheral surface of the first detected shaft is provided on the annular sensor support portion into 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 displacement measuring instrument corresponding measuring unit having at least two places in the circumferential direction, and any one of the tool post position measuring unit and the second detected shaft;
The turret is provided with the other one of the second detected shaft and the turret position measurement unit,
The tool post position measuring unit detects a gap with respect to an outer peripheral surface of the second detected shaft inserted in the support frame portion in a support frame portion in which the second detected shaft can be inserted and removed. In at least two places 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 6, 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 the command value of the movement command is provided, and the distance obtained by the spindle center / tool post distance calculation means for the command value is provided in the control device. The machine tool according to any one of claims 1 to 6, further comprising a thermal displacement correction means for performing correction according to the above. 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 The displacement measuring device which has the gap sensor which detects the clearance gap with respect to the outer peripheral surface of the to-be-detected shaft inserted in this sensor support part in the annular sensor support part in at least two places of the circumferential direction.

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