JP7123732B2 - Machine tool, program and correction amount calculation method - Google Patents

Description

The present invention relates to a machine tool, a program, and a correction amount calculation method.

As a conventional machine tool, Patent Document 1 discloses a slide portion that can move in a predetermined axial direction in order to adjust the relative position between a work (workpiece) and a tool, and thermal displacement in the moving direction of the slide portion. A machine tool is disclosed that performs correction based on the output of a touch switch.

Further, Patent Document 2 discloses a machine tool that corrects thermal displacement of a correction target axis based on the output of a temperature sensor embedded in a predetermined portion.

Japanese Patent No. 5883264 Japanese Patent No. 3136472

With the technique of using a touch switch provided corresponding to the slide portion as in Patent Document 1, it is difficult to correct thermal displacement in consideration of thermal displacement occurring in other units (such as the headstock) that do not move with the slide portion.

On the other hand, in the technique using a temperature sensor as in Patent Document 2, it is possible to correct thermal displacement in consideration of thermal displacement occurring in other units, but as shown in FIG. It is difficult to compensate for sudden thermal displacements that occur in a few minutes). This is because the heat is not sufficiently transmitted to the portion where the temperature sensor is embedded during the predetermined period, causing a deviation between the actual temperature to be corrected and the temperature detected by the temperature sensor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned actual situation. It is an object of the present invention to provide a machine tool, a program, and a method for calculating a correction amount.

In order to achieve the above object, the machine tool according to the first aspect of the present invention comprises:
a slide portion that moves in a predetermined axial direction with respect to the base and adjusts the relative position in the axial direction between the workpiece gripped by the spindle and the tool for processing the workpiece;
a detection unit that is immovable with respect to the base and detects that the detection unit has come into contact with a dog provided on the slide unit or has approached the dog by a predetermined distance;
Based on the detection by the detection unit , an axial position, which is the position of the slide unit in the axial direction at the time of detection, is acquired, and at least the detected temperature detected by a temperature sensor provided at a location different from the slide unit is obtained. calculating means for calculating a correction amount for correcting the thermal displacement in the axial direction based on at least one of the acquired axial position and the detected temperature;
drive control means for moving the slide portion to a position obtained by adding the correction amount to the target position;
with
The calculation means is
A first value indicative of the amount of thermal displacement is calculated based on a plurality of axial positions obtained during different detections, and a second value indicative of an estimated amount of thermal displacement is calculated based on the detected temperature. death,
calculating the correction amount using the first value within a predetermined period from the start of machining the workpiece, and calculating the correction amount using the second value after the predetermined period has elapsed ;
The first value indicates the amount of thermal displacement that changes over time within the predetermined period.

The machine tool further comprises a tool portion having a hollow portion through which a workpiece can pass, and the tool having a tip facing the hollow portion,
The tool portion is movable in the axial direction together with the slide portion,
The axial direction is the radial direction of the workpiece,
The dog and the detection portion may be positioned outside the hollow portion in the axial direction.

In order to achieve the above object, a machine tool according to a second aspect of the present invention comprises:
a slide portion that moves in a predetermined axial direction with respect to the base and adjusts the relative position in the axial direction between the workpiece gripped by the spindle and the tool for processing the workpiece;
detection means for detecting that the movable portion that moves in the axial direction together with the sliding portion and the stationary portion that does not move in the axial direction come into contact with each other or approach each other by a predetermined distance;
Based on the detection by the detection means, the axial position, which is the axial position of the slide portion at the time of detection, is acquired, and the detected temperature detected by a temperature sensor provided at a predetermined location is acquired. calculation means for calculating a correction amount for correcting the thermal displacement in the axial direction based on at least one of the axial position and the detected temperature;
drive control means for moving the slide portion to a position obtained by adding the correction amount to the target position;
with
The calculation means is
A first value indicative of the amount of thermal displacement is calculated based on a plurality of axial positions obtained during different detections, and a second value indicative of an estimated amount of thermal displacement is calculated based on the detected temperature. death,
The correction amount is calculated using not only the first value but also the second value within a predetermined period from the start of machining of the workpiece, and the correction amount is calculated using the second value after the predetermined period has elapsed. calculate.

The calculating means may be capable of setting one period as the predetermined period from among a plurality of periods having mutually different lengths prepared in advance.

The calculation means may change the predetermined period according to a predetermined condition.

In order to achieve the above object, a program according to the third aspect of the present invention,
A program for calculating a correction amount according to the thermal displacement in the axial direction of the machine tool,
A computer is caused to function as the calculation means and the drive control means.

According to the present invention, it is possible to satisfactorily correct thermal displacement from the start of machining of a workpiece, and to perform thermal displacement correction in consideration of thermal displacement occurring in structures other than the slide portion.

It is a mimetic diagram which looked at the machine tool concerning one embodiment of the present invention from the direction of the X-axis. (a) is a view mainly of the first processing mechanism as seen from the Z-axis direction. (b) is a view of the second machining mechanism as seen from the Z-axis direction. It is the figure which looked at the machine tool from the Y-axis direction. It is a figure which shows the installation example of a temperature sensor. FIG. 2 is a view of the machine tool as seen from the X-axis direction, and is a view mainly for explaining the installation locations of predetermined temperature sensors. 9 is a flowchart of reference position acquisition processing; 4 is a flowchart of thermal displacement correction processing; FIG. 10 is a diagram for explaining a period during which thermal displacement correction becomes difficult, which occurs in a conventional technique using a temperature sensor;

A machine tool according to an embodiment of the present invention will be described with reference to the drawings. A machine tool 1 shown in FIG. 1 is configured as a multi-function lathe for machining the front and back surfaces of a cylindrical workpiece (work) W with two spindles.

In the following, to facilitate understanding of the explanation, the horizontal direction along the center line of the workpiece W will be called the “Z-axis direction”, the vertical direction will be called the “Y-axis direction”, and the horizontal direction perpendicular to the Y-axis and Z-axis directions will be called the “Y-axis direction”. The direction is called "X-axis direction". In addition, the directions of the arrows on the X, Y, and Z axes indicated by the arrows in the drawing are the + sides.

As shown mainly in FIG. 1, the machine tool 1 includes a bed 2 as a base for the entire machine tool 1, a first machining mechanism M1, a second machining mechanism M2, a detection mechanism 200, and a temperature sensor St (Fig. 4) and a control unit 300 .

(First processing mechanism M1)
The first machining mechanism M1 is a mechanism for machining the front surface (the surface facing the +Z-axis direction) and the side surface of the workpiece W, and includes a workpiece holding unit 20, a first Z-axis slide mechanism 30, and a tool moving mechanism 40. .

The work holding unit 20 includes a spindle 21 and a headstock 22 that rotatably supports the spindle 21 . The headstock 22 incorporates a work rotation motor (not shown). This work rotation motor rotates the work W gripped by a chuck 21 a provided on the main shaft 21 .

The first Z-axis slide mechanism 30 is a mechanism for moving the workpiece holding part 20 in the Z-axis direction, and is supported by a bearing part 31 mounted on the bed 2 and extending in the Z-axis direction. It includes a ball screw 32, a first Z-axis motor 33 that rotates the ball screw 32, and a first Z-axis slide section 34 on which the headstock 22 is installed. The first Z-axis slide portion 34 has a nut 35 that engages with the ball screw 32 . The nut 35 moves in the Z-axis direction when the ball screw 32 rotates.
The first Z-axis slide mechanism 30 rotates the ball screw 32 with the first Z-axis motor 33 to move the first Z-axis slide portion 34 together with the nut 35, thereby moving the workpiece holding portion 20 in the Z-axis direction. Therefore, in the first processing mechanism M1, the work W can be moved in the Z-axis direction while the work W is held by the chuck 21a and rotated by the work rotation motor.

The tool moving mechanism 40 is a mechanism for moving a tool Tf (see FIG. 2(a)) for machining the workpiece W in the X-axis direction and the Y-axis direction. , an X-axis moving portion 44 provided on the fixed base 41 and a Y-axis moving portion 50 provided on the X-axis moving portion 44 .

The fixed base 41 includes a rail portion Rx1 extending in the X-axis direction, a hollow flange 43a attached to a hollow portion 41H penetrating in the Z-axis direction, and a guide bush 43b attached to the inner surface of the flange 43a. The guide bush 43b assists in holding and moving the work W. The fixed table 41 also includes a first X-axis slide mechanism 10, as shown in FIG.

The first X-axis slide mechanism 10 is a mechanism for moving the X-axis moving part 44 in the X-axis direction. An extending ball screw 12 and a first X-axis motor 13 for rotating the ball screw 12 are provided. A nut 15 fitted to the ball screw 12 moves in the X-axis direction when the ball screw 12 rotates. The first X-axis slide mechanism 10 rotates the ball screw 12 with the first X-axis motor 13, thereby moving a first X-axis slide portion 45 having a nut 15, which will be described later, in the X-axis direction.

The X-axis moving portion 44 is a portion that moves in the X-axis direction on the rail portion Rx1 by the first X-axis slide mechanism 10, and includes a first X-axis slide portion 45, a guide groove portion Gx1, a bearing portion 46, a ball screw 47, and a Y-axis motor 48 .

The first X-axis slide portion 45 has a substantially flat plate shape. The ball screw 47 is housed inside the first X-axis slide portion 45, as shown in FIG. The guide groove portion Gx1 extends in the X-axis direction and is provided on one surface of the substantially flat plate shape. The guide groove portion Gx1 engages with the rail portion Rx1 of the fixed base 41 . As shown in FIG. 3, a guide groove portion Gy1 extending in the Y-axis direction is provided on the other substantially flat surface. The guide groove portion Gy1 guides the movement of the Y-axis moving portion 50 in the Y-axis direction. The first X-axis slide portion 45 is formed with a hollow portion 45H through which the workpiece W gripped by the main shaft 21 can pass. The bearing portion 46 rotatably supports a ball screw 47 . The ball screw 47 thus supported is arranged to extend in the Y-axis direction and is rotated by a Y-axis motor 48 .

The Y-axis moving portion 50 is a portion that moves in the Y-axis direction along the guide groove portion Gy1, and includes a Y-axis slide portion 51, and a tool holding portion 52 and a nut 53 provided on the Y-axis slide portion 51. . Since the Y-axis moving portion 50 is provided in the X-axis moving portion 44, when the X-axis moving portion 44 moves in the X-axis direction by the first X-axis slide mechanism 10, the Y-axis moving portion 50 also moves in the X-axis direction. move to

The Y-axis slide portion 51 has a substantially flat plate shape. A hollow portion 51H through which the workpiece W gripped by the main shaft 21 can pass is formed in the substantially flat main surface (the surface parallel to the Y-axis).
The tool holding portion 52 is provided on the main surface of the Y-axis slide portion 51 . As shown in FIG. 2A, the tool holding portion 52 is arranged along the left and right ends of the hollow portion 51H. The tool holding portion 52 holds a tool Tf including a plurality of cutting tools, drills, and the like. For example, as shown in FIG. 2(a), the tools Tf include nine tools facing the X-axis direction and toward the central portion of the hollow portion 51H, and four drills facing the −Z-axis direction (indicated by dotted lines in FIG. 2). shown) and Bits that constitute the tool Tf include a cutting bit that cuts the workpiece W. As shown in FIG. Moreover, the front surface of the workpiece W can be machined by the drill that constitutes the tool Tf.
A rail portion Ry1 extending along the Y-axis direction is provided on the back surface of the surface of the Y-axis slide portion 51 on which the tool holding portion 52 is provided. The rail portion Ry1 is slidable in the guide groove portion Gy1 provided in the first X-axis slide portion 45. As shown in FIG.
The first machining mechanism M1 rotates the ball screw 47 with the Y-axis motor 48, thereby moving the nut 53 fitted to the ball screw 47, thereby moving the Y-axis moving part 50 in the Y-axis direction.

With the above configuration, the X-axis moving portion 44 of the tool moving mechanism 40 can move in the X-axis direction, and the Y-axis moving portion 50 can move in the Y-axis direction. Accordingly, the tool Tf is also movable in the X-axis and Y-axis directions.

(Second processing mechanism M2)
The second processing mechanism M2 is a mechanism for processing the back surface (the surface facing the −Z-axis direction) and the side surface of the work W, and includes a work holding unit 70, a second Z-axis slide mechanism 80, and a second X-axis slide mechanism 90. , and a tool table 100 .

The work holding unit 70 includes a spindle 71 and a headstock 72 that rotatably supports the spindle 71 . The headstock 72 incorporates a work rotation motor (not shown). This work rotation motor rotates the work W gripped by a chuck 71 a provided on the main shaft 71 . The headstock 72 is installed on a second X-axis slide portion 91 of the second X-axis slide mechanism 90, which will be described later.

The second Z-axis slide mechanism 80 is a mechanism for moving the work holding portion 70 in the Z-axis direction, and includes a bearing portion 81 and a bearing portion 61 provided on a fixed table 60 fixed on the bed 2, and a bearing portion 81 and bearing 61 and extending in the Z-axis direction; a second Z-axis motor 83 that rotates the ball screw 82; , and a rail portion Rz2 provided on a fixed base 60, as shown in FIG. The bearing portion 81 receives the second Z-axis motor 83 side of the ball screw 82 , and the bearing portion 61 receives the tip portion of the ball screw 82 .
The second Z-axis slide portion 84 has a nut 85 fitted with the ball screw 82 and a guide groove portion Gz2 (see FIG. 2B) extending in the Z-axis direction. The nut 85 moves in the Z-axis direction when the ball screw 82 rotates. The guide groove portion Gz2 engages with the rail portion Rz2.
The second Z-axis slide mechanism 80 rotates the ball screw 82 with the second Z-axis motor 83 to move the second Z-axis slide portion 84 together with the nut 85 . Thereby, the work holding part 70 can move on the rail part Rz2 extending in the Z-axis direction.

The second X-axis slide mechanism 90 is a mechanism for moving the work holding portion 70 in the X-axis direction, and as shown in FIG. A bearing portion 92 provided above, a ball screw 93 that is supported by the bearing portion 92 and extends in the X-axis direction, and a second X-axis motor 94 that rotates the ball screw 93 are provided.
A headstock 72 is installed on the second X-axis slide portion 91 . The second X-axis slide portion 91 has a nut 95 (see FIG. 3) that engages with the ball screw 93 and a guide groove portion Gx2 (see FIGS. 1 and 3) extending in the X-axis direction below the second X-axis slide portion 91 . The nut 95 moves in the X-axis direction when the ball screw 93 rotates. The guide groove portion Gx2 engages with the rail portion Rx2 as shown in FIG.
The second X-axis slide mechanism 90 moves the second X-axis slide portion 91 together with the nut 95 by rotating the ball screw 93 with the second X-axis motor 94 . Thereby, the work holding part 70 can move on the rail part Rx2 extending in the X-axis direction. In addition, since the second X-axis slide mechanism 90 is arranged on the second Z-axis slide mechanism 80, the second Z-axis slide mechanism 80 moves the second Z-axis slide portion 84 in the Z-axis direction to move the second X-axis slide. The portion 91 also moves in the Z-axis direction.

With the above configuration, the work W held by the work holding portion 70 is movable in the X-axis and Z-axis directions.

The tool table 100 holds a tool Tr such as a drill, a tap, a turning bit, a boring bit, etc., which is attached so that the tip faces the +Z-axis direction. In this embodiment, there are a plurality of tools Tr. For example, as shown in FIG. 3, four tools Tr are provided at predetermined intervals in the X-axis direction to form a comb-like shape.
The tool table 100 is supported by a support member 101 provided on the bed 2 and is immovable with respect to the bed 2, as shown in FIG. 2(a). The tool Tr (see FIG. 3) held by the tool rest 100 is positioned so that its tip (for example, the center of the axis) is positioned at the center of the axis of the work W held by the work holding unit 70 of the second machining mechanism M2. are placed in

(Detection mechanism 200)
The detection mechanism 200 includes detection units Sp1 to Sp3 and dogs D1 to D3. The detectors Sp1, Sp2 and the dogs D1, D2 are provided in the first machining mechanism M1. The detection part Sp3 and the dog D3 are provided in the second processing mechanism M2. Each of the detection units Sp1 to Sp3 is composed of, for example, a touch switch.

The detector Sp1 is provided to measure thermal displacement in the X-axis direction (mainly due to the ball screw 12 extending in the X-axis direction) in the first X-axis slide mechanism 10 of the first processing mechanism M1. there is Since the ball screw 12 is supported by the first X-axis motor 13, the ball screw 12 extends in the −X-axis direction when heat is generated by the first X-axis motor 13 or the like and causes thermal displacement.

When the tip portion of the detection portion Sp1 contacts the dog D1, the detection portion Sp1 supplies an ON signal indicating the contact to the control portion 300. As shown in FIG. As shown in FIG. 3, the dog D1 is formed as part of the side surface (the surface facing the -X direction) of the first X-axis slide portion 45. As shown in FIG. The dog D1 moves in the X-axis direction as the first X-axis slide portion 45 moves. The detection part Sp1 is attached to an attachment part 41a protruding from the fixing base 41, as shown in FIGS. The detector Sp1 attached in this manner is immobile with respect to the bed 2 and does not move in the X-axis direction. The detection part Sp1 and the dog D1 are arranged at positions facing each other in the X-axis direction. The detecting portion Sp1 and the dog D1 come into contact with each other when the dog D1 is moved by a predetermined amount in the -X-axis direction due to the movement of the first X-axis slide portion 45 .

In particular, as shown in FIG. 3, the dog D1 (moving portion that moves in the X-axis direction together with the first X-axis slide portion 45) and the detection portion Sp1 (non-moving portion that does not move in the X-axis direction) are hollow in the X-axis direction. It is positioned outside the portion 51H. Further, the dog D1 and the detecting portion Sp1 are positioned so as not to overlap the Y-axis slide portion 51 (an example of the tool portion) in the X-axis direction. In other words, the dog D1 and the detecting portion Sp1 are located away from the tool Tf facing the workpiece W. As shown in FIG. By doing so, it is possible to prevent chips generated during machining of the workpiece W from adhering to the dog D1 and the detection part Sp1, thereby preventing deterioration in detection accuracy.

Further, the detection portion Sp1 is located outside the first X-axis slide portion 45 in the X-axis direction. In this way, by providing the detector Sp1 that outputs a signal to a portion that is immovable with respect to the bed 2 instead of providing it to a movable portion such as the first X-axis slide portion 45, the vibration applied to the detector Sp1 can be reduced. can be suppressed, and a decrease in detection accuracy can be prevented.

The detection part Sp2 is provided to measure thermal displacement in the Y-axis direction (mainly thermal displacement due to the ball screw 47 extending in the Y-axis direction) in the Y-axis moving part 50 of the first processing mechanism M1. . Since the ball screw 47 is supported by the Y-axis motor 48, the ball screw 47 extends in the -Y-axis direction when thermal displacement occurs due to heat generated by the Y-axis motor 48 or the like.

When the tip portion of the detection portion Sp2 contacts the dog D2, the detection portion Sp2 supplies an ON signal indicating the contact to the control portion 300. As shown in FIG. As shown in FIG. 1, the dog D2 is provided on the first X-axis slide portion 45 and does not move in the Y-axis direction. The detector Sp2 is attached to a mounting portion 51a extending from the Y-axis slide portion 51 in the -Z direction and reaching the rear side of the first X-axis slide portion 45, as shown in FIG. The detection part Sp2 attached in this manner moves in the Y-axis direction as the Y-axis slide part 51 moves. The detection part Sp2 and the dog D2 are arranged at positions facing each other in the Y-axis direction. The detecting portion Sp2 and the dog D2 come into contact with each other when the detecting portion Sp2 is moved by a predetermined amount in the −Y-axis direction due to the movement of the Y-axis slide portion 51 .

The detector Sp3 is provided to measure thermal displacement in the Z-axis direction (mainly due to the ball screw 82 extending in the Z-axis direction) in the second Z-axis slide mechanism 80 of the second processing mechanism M2. there is Since the ball screw 82 is supported by the second Z-axis motor 83, the ball screw 82 extends in the −Z-axis direction when heat is generated by the second Z-axis motor 83 or the like and causes thermal displacement.

When the tip portion of the detection portion Sp3 contacts the dog D3, the detection portion Sp3 supplies the control portion 300 with an ON signal indicating the contact. The dog D3 is provided so as to protrude from the fixed base 60 in the +X direction, as shown in FIG. The dog D3 is immobile with respect to the bed 2 and does not move in the Z-axis direction. As shown in FIG. 3, the detection part Sp3 is attached to an attachment part 84a protruding from the second Z-axis slide part 84 in the +Z direction. The detection part Sp3 attached in this manner moves in the Z-axis direction as the second Z-axis slide part 84 moves. The detection part Sp3 and the dog D3 are arranged at positions facing each other in the Z-axis direction. The detecting portion Sp3 and the dog D3 come into contact with each other when the detecting portion Sp3 moves in the +Z-axis direction by a predetermined amount due to movement of the second Z-axis slide portion 84 .

(Temperature sensor St)
The temperature sensor St is composed of, for example, a thermistor, and is provided in plurality. The multiple temperature sensors St output to the controller 300 a signal indicating the detected temperature at each installation location. As shown in FIG. 4, the temperature sensor St is provided in a mode (embedded mode) in which it is directly inserted into an installation location or inserted into a metal (for example, stainless steel) block fixed to the installation location. As an exception, a temperature sensor St8, which will be described later, is not provided in an embedded manner.

Hereinafter, each of the plurality of temperature sensors St will be denoted by reference numerals for each installation position, and will be referred to as temperature sensors St1 to St8. FIG. 3 shows the locations where the temperature sensors St1, St4, St7, and St8 are installed. FIG. 5 shows the locations where the temperature sensors St2, St3, and St5 are installed. The location where the temperature sensor St6 is installed is shown in FIG. 2(a).

The temperature sensors St1 to St3 are provided in the first processing mechanism M1.
The temperature sensor St1 detects the ambient temperature of the ball screw 12 extending in the X-axis direction, and is provided near the bearing portion 11 on the fixed base 41, for example.
The temperature sensor St<b>2 detects the ambient temperature of the ball screw 47 extending in the Y-axis direction, and is provided near the bearing portion 46 in the first X-axis slide portion 45 , for example.
The temperature sensor St3 detects the ambient temperature of the fixed table 41, and is provided, for example, in the upper portion of the cavity 41H in the fixed table 41. As shown in FIG.

The temperature sensors St4 to St6 are provided in the second processing mechanism M2.
The temperature sensor St4 detects the ambient temperature of the ball screw 93 extending in the X-axis direction, and is provided near the bearing portion 92 in the second Z-axis slide portion 84, for example.
The temperature sensor St5 detects the ambient temperature of the ball screw 82 extending in the Z-axis direction, and is provided near the bearing portion 61 on the fixed base 60, for example.
The temperature sensor St6 detects the ambient temperature of the tool Tr (see FIG. 3) on the tool base 100, and is provided at a position near the tool base 100 on the support member 101, for example.

The temperature sensor St7 detects the ambient temperature of the bed 2, and is provided at the leg 2a of the bed 2, for example.
The temperature sensor St8 detects the room temperature (that is, the ambient temperature of the machine tool 1 itself), and is provided at a predetermined location in the machine tool 1 in a non-buried manner.

(control unit 300)
The control unit 300 controls the operation of each part of the machine tool 1, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory) for storing a program defining the procedure of processing by the CPU, and an appropriate numerical value input by the user. It is equipped with a RAM (random access memory) that temporarily stores programs that are executed in response to input and other necessary information, and a timer that keeps time. A program PG (see FIG. 1) for executing a "reference position acquisition process" and a "thermal displacement correction process", which will be described later, is stored in advance in the ROM of the control unit 300, and the CPU reads out these programs. ,Run. Note that the control unit 300 may control the operation of each unit of the machine tool 1 in cooperation with the CPU and other dedicated circuits.

The control unit 300 moves the work holding unit 20 in the Z-axis direction and the tool holding unit 52 in the X-axis and Y-axis directions by numerical control (NC (Numerical Control)) to control the relative movement of the work W and the tool Tf. appropriate positional relationship. Specifically, the above relationship is realized by driving and controlling the work rotation motor, first Z-axis motor 33, first X-axis motor 13, and Y-axis motor 48 of the first machining mechanism M1. Also, the control unit 300 moves the work holding unit 70 in the X-axis and Z-axis directions by numerical control, and appropriately sets the relative positional relationship between the work W and the tool Tr. Specifically, the above relationship is realized by driving and controlling the work rotation motor, the second Z-axis motor 83, and the second X-axis motor 94 of the second machining mechanism M2.

Next, machining of the workpiece W by the machine tool 1 having the above configuration will be described. In the machine tool 1 according to the present embodiment, the first machining mechanism M1 first performs the primary machining of the workpiece W, and then the second machining mechanism M2 further processes the workpiece W that has undergone the primary machining (secondary machining). processing). This processing is performed under the control of the control unit 300 .

(Regarding work processing)
(1) Primary Machining The control unit 300 indexes a predetermined tool Tf from among the plurality of tools Tf of the tool holding unit 52 to machine the workpiece W. As shown in FIG. Specifically, the Y-axis motor 48 is driven to move the Y-axis moving unit 50 so that the desired tool Tf is positioned at the same height as the workpiece W. Next, the control unit 300 drives the work rotation motor and the first Z-axis motor 33 to move the work W in the Z-axis direction while rotating it, and at the same time or with a time lag, drives the first X-axis motor 13. Then, the X-axis moving part 44 is moved toward the work W by the first X-axis slide mechanism 10 .
In this way, the tool Tf such as a cutting tool or a drill is brought into contact with the front surface or side surface of the work W, and the work W is primarily processed by the first processing mechanism M1.

(2) Secondary Machining After completing the primary machining, the control unit 300 drives the second Z-axis motor 83 and the second X-axis motor 94 to move the workpiece holding unit 70, and chuck the workpiece W that has undergone the primary machining. 71a is made to grasp. Subsequently, the control unit 300 drives the work rotation motor and the first X-axis motor 13 to move the first X-axis slide unit 45 toward the work W, and the work W is moved to a desired position by the cutting bit of the tool Tf. Cut at position. It should be noted that FIG. 1 and the like show the state after the work W has been cut in this way.
Subsequently, the control unit 300 indexes a predetermined tool Tr from among the plurality of tools Tr on the tool table 100, and grips it by the second Z-axis slide mechanism 80 and the second X-axis slide mechanism 90 while rotating the main shaft 71. The selected tool Tr is brought into contact with the back surface or side surface of the work W, and the work W is processed further.
In this manner, the second processing mechanism M2 secondary-processes the workpiece W. As shown in FIG.

As described above, the machine tool 1 that processes the workpiece W determines the positions of the predetermined tools Tf and Tr by taking into account the "correction amount" corresponding to the thermal displacement in the axial direction of the object to be measured. In other words, when the relative positions of the predetermined tools Tf, Tr and the workpiece W are set to the set target positions, the target positions are set to the positions to which the correction amount is added.

Processing for calculating the correction amount will now be described. The control unit 300 first executes a “reference position acquisition process” for acquiring a reference position that serves as a reference for obtaining a first thermal displacement amount, which will be described later, and then executes a “thermal displacement correction process”.

The control unit 300 corrects thermal displacement in the X-axis direction in the first machining mechanism M1, thermal displacement in the Y-axis direction in the first machining mechanism M1, and thermal displacement in the Z-axis direction in the second machining mechanism M2. Although possible, the approach to thermal displacement compensation in each direction is similar. Therefore, the thermal displacement in the X-axis direction in the first machining mechanism M1 will be mainly described below.

(Reference position acquisition processing)
Reference position acquisition processing executed by the control unit 300 will be described with reference to the flowchart of FIG. This process is started, for example, on the condition that the power of the machine tool 1 is turned on.

When starting the reference position acquisition process, the control section 300 first moves the first X-axis slide section 45 to the detection standby position (step S11). Specifically, the control section 300 drives the first X-axis motor 13 to move the first X-axis slide section 45 to the detection standby position where the dog D1 approaches the tip of the detection section Sp1. The detection standby position is a position in which the dog D1 and the detection part Sp1 are spaced apart from each other to the extent that they do not erroneously contact each other due to the recoil of movement. is a position of several millimeters.

Subsequently, the control unit 300 drives the first X-axis motor 13 to move the first X-axis slide unit 45 in the -X direction, thereby starting detection (step S12). As a result, the dog D1 gradually approaches the detector Sp1. When the dog D1 contacts the tip of the detection part Sp1, the detection part Sp1 supplies a detection signal (ON signal) to the control part 300. As shown in FIG. By receiving this detection signal, the control unit 300 detects that the detection unit Sp1 has come into contact with the dog D1, acquires the X-coordinate at the time of receiving the detection signal (step S13), stores the data in the RAM, etc. memorize to The X coordinate acquired here is the coordinate for an arbitrary predetermined origin position (X=0). The origin position may be, for example, a predetermined position (for example, the tip position of the ball screw 12) when the first X-axis slide portion 45 moves most in the -X-axis direction. For example, the control unit 300 adjusts the number of rotations of the first X-axis motor 13 (number of rotations=rotation angle/360°) at the time of receiving the detection signal to the lead of the ball screw 12 (the nut 15 rotates per rotation of the ball screw 12). X-coordinate at the time when the detection signal is received is obtained by multiplying by the distance traveled in the X-axis direction. Control unit 300 stores the acquired X coordinate as a reference position. This reference position is used when calculating a first thermal displacement amount, which will be described later. After executing the process of step S13, the reference position acquisition process ends.

Next, thermal displacement correction processing will be described with reference to the flowchart of FIG.

(Thermal displacement correction processing)
The control unit 300 starts the thermal displacement correction process, for example, on the condition that a signal indicating an instruction to start machining the workpiece W (hereinafter referred to as a machining start instruction) is received.

First, the control unit 300 determines whether or not a predetermined period of time has elapsed after receiving the machining start instruction (step S20). The predetermined period is a period (for example, several minutes) longer than the period (see FIG. 8) during which good thermal displacement correction becomes difficult when only the temperature sensor St is used, and is stored in advance in the ROM.

If the predetermined period has not elapsed (step S20; No), the control section 300 moves the first X-axis slide section 45 to the detection standby position (step S21), as in step S11 described above. After that, the control unit 300 executes the processes of steps S21 to S23, and these processes are the same as those of steps S11 to S13 described above.

The control unit 300 acquires the X coordinate at the time of receiving the detection signal from the detection unit Sp1 (step S23), stores it in the RAM or the like, and calculates the first thermal displacement amount α (step S24). Specifically, the control unit 300 calculates a value obtained by subtracting the X coordinate as the reference position acquired in step S13 from the X coordinate acquired in step S23 as the first thermal displacement amount α. If α is a positive value, the ball screw 12 is elongated by α due to thermal displacement. On the other hand, if α is a negative value, it means that the ball screw 12 has contracted by α due to thermal displacement.

Subsequently, the control section 300 moves the first X-axis slide section 45 to the processing standby position, and then starts processing the workpiece W (step S25). The processing standby position may be, for example, the same position as the detection standby position.

The machining of the workpiece W in step S25 is performed in the same manner as the procedures (1) and (2) described above in (Regarding machining of workpiece).
If the predetermined period has not elapsed (step S20; No), the first thermal displacement amount α obtained in step S24 is used as the correction amount, and the first X-axis slide portion 45 is moved to a position to which the correction amount is added. Let Specifically, if X=A is the preset target coordinate of the first X-axis slide unit 45, the control unit 300 adjusts the position of the corrected target coordinate (X=A+α) by adding the correction amount α to the target coordinate. Then, by moving the first X-axis slide portion 45, the work W is machined by the first machining mechanism M1.

On the other hand, if the predetermined period has passed (step S20; Yes), the control unit 300 acquires the detected temperatures T1 to T8 at each location based on the outputs of the temperature sensors St1 to St8 (step S26).

Subsequently, the control unit 300 calculates the second thermal displacement amount β based on the obtained detected temperatures T1 to T8 and the correction formula (formula data) stored in advance in the ROM (step S27). For example, the correction formula is a formula represented by "β=a·T1+b·T2+c·T3+d·T4+e·T5+f·T6+g·T7+h·T8+i" where a to i are predetermined coefficients. Note that the coefficients a to i can be determined in advance by multiple regression analysis. The control unit 300 substitutes the obtained detected temperatures T1 to T8 into the correction formula to calculate the second thermal displacement amount β.

Subsequently, the control section 300 starts machining the workpiece W in the same manner as described above (step S25). However, if the predetermined period has passed (step S20; Yes), the second thermal displacement amount β obtained in step S27 is used as the correction amount, and the first X-axis slide portion 45 is moved to the position to which the correction amount is added. to move. Specifically, if X=A is the preset target coordinate of the first X-axis slide unit 45, the control unit 300 adjusts the position of the corrected target coordinate (X=A+β) by adding the correction amount β to the target coordinate. Then, by moving the first X-axis slide portion 45, the work W is machined by the first machining mechanism M1.

After finishing machining one workpiece W, the control unit 300 returns the process to step S20. The control unit 300 repeatedly executes the above process until receiving a signal indicating an instruction to end processing. The acquisition of the detected temperatures T1 to T8 and the calculation of the second thermal displacement amount β based on the acquired detected temperatures T1 to T8 may be performed at predetermined intervals while one work W is being processed. Alternatively, the thermal displacement process may be performed only when an arbitrary tool is indexed from the plurality of tools Tf.

Correction of thermal displacement in the Y-axis direction in the first machining mechanism M1 and correction of thermal displacement in the Z-axis direction in the second machining mechanism M2 can be performed in the same manner.
Briefly, when correcting the thermal displacement in the Y-axis direction in the first machining mechanism M1, the control unit 300 moves the Y-axis moving unit 50 in the -Y direction in the reference position acquisition process, so that the detection unit Sp2 is brought into contact with dog D2 to acquire the reference position of the Y coordinate. In the thermal displacement correction process, the first thermal displacement amount in the Y-axis direction is used as the correction amount within the predetermined period, and The second thermal displacement amount may be used as the correction amount.
Further, when correcting thermal displacement in the Z-axis direction in the second machining mechanism M2, the control unit 300 moves the second Z-axis slide unit 84 in the +Z direction in the reference position acquisition process, thereby moving the detection unit Sp3 to the dog D3. to obtain the reference position of the Z coordinate. In the thermal displacement correction process, the first thermal displacement amount in the Z-axis direction is used as the correction amount within the predetermined period, and The second thermal displacement amount may be used as the correction amount.
The value of each coefficient of the correction formula used when obtaining the second thermal displacement amount can be determined in advance by multiple regression analysis for each axis to be corrected for thermal displacement.

In addition, this invention is not limited by the above embodiment and drawing. Modifications (including deletion of components) can be made as appropriate without changing the gist of the present invention.

An example has been described above in which the dog D1 is a moving portion that moves in the X-axis direction together with the first X-axis slide portion 45, and the detection portion Sp1 is a stationary portion that does not move in the X-axis direction. Sp1 may be arranged so as to move in the X-axis direction, and the relationship between the moving part and the immovable part may be reversed. That is, the detecting portion Sp1 may be a moving portion that moves in the X-axis direction together with the first X-axis sliding portion 45, and the dog D1 may be a stationary portion that does not move in the X-axis direction. The same applies to the relative movement relationship between the detection part Sp2 and the dog D2 in the Y-axis direction and the relative movement relationship between the detection part Sp3 and the dog D3 in the Z-axis direction.

Further, if the control axes of the first machining mechanism M1 are X1, Y1, and Z1, and the control axes of the second machining mechanism M2 are X2, Y2, and Z2 corresponding to the X, Y, and Z axial directions, the above Although an example of correcting thermal displacement in each of the X1, Y1, and Z2 axes has been described, the present invention is not limited to this. It is arbitrary which of the X1, Y1, Z1, X2, Y2, and Z2 axes is used as the thermal displacement correction target axis.

In the above example, eight temperature sensors St1 to St8 are used as the plurality of temperature sensors St, but the location and number of the plurality of temperature sensors St are arbitrary. Further, the temperature sensor St is not limited to one using a thermistor, and may be, for example, a sensor that detects temperature by infrared radiation, a semiconductor temperature sensor, or the like.

In the above description, an example of calculating the second thermal displacement amount based on the correction formula (data representing the formula) stored in advance in the ROM has been described. A thermal displacement amount may be calculated. The table data can be configured by associating a predetermined set value (for example, a value indicating thermal displacement at each installation location) with the detected temperature at each installation location of the temperature sensor St. For example, the control unit 300 can acquire a plurality of set values corresponding to each detected temperature by referring to table data, and add up the acquired set values to obtain the second thermal displacement amount.

In the above description, the first thermal displacement amount is used as the thermal displacement correction amount within a predetermined period from the start of machining of the workpiece W, and the second thermal displacement amount is used as the thermal displacement correction amount after the predetermined period has elapsed. Illustrated, but not limited to. For example, the thermal displacement correction amount may be obtained by multiplying the first amount of thermal displacement obtained within a predetermined period by a coefficient, or by multiplying the second amount of thermal displacement obtained after the elapse of the predetermined period by a coefficient. may be the correction amount.

Further, not only the first thermal displacement amount but also the second thermal displacement amount are calculated within a predetermined period from the start of machining of the workpiece W, and correction is performed based on the first thermal displacement amount and the second thermal displacement amount within the predetermined period. amount may be calculated. In such a case, a simple average or a weighted average of the first thermal displacement amount and the second thermal displacement amount can be obtained, and the obtained value can be used as the thermal displacement correction amount. As shown in FIG. 8, it is difficult to correct thermal displacement based only on the output of the temperature sensor St within the predetermined period. It is preferable to perform a calculation in which the first thermal displacement amount calculated based on the output of the detection unit Sp1 acts preferentially over the second thermal displacement amount calculated based on the above. Alternatively, after a predetermined period of time has elapsed, not only the second thermal displacement amount but also the first thermal displacement amount may be calculated, and the correction amount may be calculated based on the first thermal displacement amount and the second thermal displacement amount.

In the above description, an example in which the detection unit Sp1 (the same applies to the detection units Sp2 and Sp3) is configured by a touch switch (an example of a contact sensor) is shown, but the present invention is not limited to this. The detector Sp1 may be a non-contact sensor. The non-contact sensor is, for example, an eddy-current distance measuring device, which measures the distance between itself and the target dog D1 (the same applies to dogs D2 and D3) and supplies the measured value to the control unit 300. is. Specifically, the control unit 300 causes a high-frequency current to flow through a coil included in the eddy-current distance measuring device, and generates an eddy current on the surface of the dog D1 by electromagnetic induction, thereby changing the distance between the two. Obtaining the impedance of the coil and measuring the distance based on the obtained impedance value. In this case, in steps S13 and S23, the control unit 300 may acquire the coordinates at the time when the measured value reaches the previously stored distance. Moreover, the contact sensor is not limited to the touch switch, and the non-contact sensor is not limited to the eddy current distance measuring device. Both the contact sensor and the non-contact sensor may be arbitrarily selected from various known sensors.

In the above description, the control unit 300 starts machining the workpiece (step S25), and after machining one workpiece W, returns the process to step S20, but the present invention is not limited to this. The control unit 300 may return to the process of step S20 after machining a plurality of works W or after a predetermined machining period has elapsed.

Further, in step S20 described above, the period to be compared with the predetermined period (hereinafter referred to as the target period T) has been described as the elapsed period from the time when the machining start instruction is received, but it is not limited to this. . For example, if the target period T is Ta, which is the sum of the machining periods (operating periods) of the machine tool 1, and Tb, which is the sum of the non-operating periods of the machine tool 1, T = Ta - γ Tb (γ is a coefficient ) may be a value that can be calculated by Note that the coefficient γ is a value considering that the influence on thermal deformation is different between the operation stop period and the machining period, and is arbitrary, but can be set to γ=2, for example. That is, the control unit 300 can calculate the target period T using the above formula, and may determine whether the calculated target period T is longer than a predetermined period when executing step S20. . In addition, a plurality of predetermined periods are prepared or variable, and the predetermined period can be changed according to conditions (for example, when performing thermal displacement correction processing for each workpiece W processing, when a plurality of workpieces W A configuration in which a different predetermined period can be set depending on whether the thermal displacement correction process is executed for each machining may be adopted.

Moreover, although the tool table 100 is assumed to be immovable with respect to the bed 2 in the above description, the present invention is not limited to this. The tool table 100 may be movable in the Y-axis direction, for example, to adjust the position of the tool Tr in the height direction with respect to the spindle 71 .

Moreover, although the machine tool 1 has been described above as a multifunctional lathe, it is not limited to this. A machine tool corresponding to only the first machining mechanism M1 or a machine tool corresponding to only the second machining mechanism M2 may be used. Also, the machine tool may be a milling machine, a drilling machine, or the like.

Further, although the operation program (program PG) for the CPU of the control unit 300 to execute the reference position acquisition process and the thermal displacement correction process is pre-stored in the ROM of the control unit 300, The operating program and various data may be distributed/provided to the computer included in the machine tool 1 via a detachable recording medium. Furthermore, the operating program and various data may be distributed by being downloaded from another device connected via a telecommunications network or the like.

Moreover, each process can be executed not only by loading a detachable recording medium, but also by temporarily storing an operation program and various data downloaded via a telecommunication network or the like in a built-in storage device. Alternatively, it may be directly executed using hardware resources of another device connected via a telecommunications network or the like. Furthermore, each processing may be executed by exchanging various data with other devices via a telecommunication network or the like.

(1) The machine tool 1 described above moves in a predetermined axial direction (for example, the X-axis direction) with respect to a base (bed S) to machine the work W gripped by the main shaft and the work W. A slide portion (e.g., the first X-axis slide portion 45) that adjusts the relative position in the axial direction with the tool, a moving portion (e.g., dog D1) that moves in the axial direction together with the slide portion, and a stationary portion that does not move in the axial direction (for example, the detection unit Sp1) and a detection means (detection mechanism 200) for detecting contact or approach by a predetermined distance;
The control unit 300 functions as calculation means and drive control means. The calculation means acquires an axial position, which is the axial position of the slide portion at the time of detection, based on the detection by the detection means, acquires a detected temperature detected by a temperature sensor St provided at a predetermined location, A correction amount for correcting thermal displacement in the axial direction is calculated based on at least one of the acquired axial position and the detected temperature. The drive control means moves the slide portion to a position obtained by adding a correction amount to the target position.
The calculation means calculates a first value (first thermal displacement amount) indicating the amount of thermal displacement based on a plurality of axial positions acquired at different detection times, and estimates the amount of thermal displacement based on the detected temperature. A second value (second thermal displacement amount) indicating a value is calculated, the correction amount is calculated using the first value within a predetermined period from the start of machining of the work, and the second value is calculated after the predetermined period has passed. is used to calculate the correction amount.

According to the configuration (1) above, it is possible to satisfactorily correct thermal displacement from the start of machining of the workpiece W, and to perform thermal displacement correction in consideration of thermal displacement occurring in structures other than the slide portion. Note that when an example of the sliding portion is the Y-axis sliding portion 51, the detection portion Sp2 is an example of the moving portion, and the dog D2 is an example of the immovable portion. Further, when an example of the slide portion is the second Z-axis slide portion 84, the detection portion Sp3 is an example of the moving portion, and the dog D3 is an example of the immovable portion.

(2) The machine tool 1 has a hollow portion 51H through which the workpiece W can pass, and a tool portion (a Y-axis slide portion provided with the tool holding portion 52) having a tool Tf whose tip faces the hollow portion 51H. 51). Since the Y-axis moving portion 50 is provided in the X-axis moving portion 44, the tool portion can move in the X-axis direction together with the first X-axis sliding portion 45 (slide portion). Further, the dog D1 and the detection portion Sp1 are positioned outside the hollow portion 51H in the X-axis direction.

According to the configuration (2) above, as described above, it is possible to prevent chips generated during machining of the workpiece W from adhering to the dog D1 and the detecting portion Sp1, thereby preventing deterioration in detection accuracy. Moreover, since the X-axis direction is the radial direction of the workpiece W, machining accuracy in the radial direction of the workpiece W can be enhanced.

(3) In addition, the dog D1 and the detection portion Sp1 are positioned so as not to overlap the tool portion (the Y-axis slide portion 51 provided with the tool holding portion 52) in the X-axis direction.

According to the above configuration (3), as described above, it is possible to prevent chips generated during machining of the workpiece W from adhering to the dog D1 and the detection part Sp1, thereby preventing deterioration in detection accuracy.

(4) Further, the detection portion Sp1 as a stationary portion is a contact sensor located outside the first X-axis slide portion 45 in the X-axis direction.

According to the above configuration (4), as described above, it is possible to suppress the vibration applied to the detection part Sp1, and prevent deterioration of the detection accuracy.

(5) Further, the calculation means acquires the detected temperature from each of the plurality of temperature sensors St, and the plurality of temperature sensors is a ball screw for moving the first X-axis slide portion 45 (slide portion) in the X-axis direction. 12, and temperature sensors St2 to St8 for detecting the ambient temperature of components other than the ball screw 12. FIG.

With configuration (5) above, it is possible to perform thermal displacement correction in consideration of thermal displacement occurring in other units that do not move together with the slide portion.

(6) Further, the calculation means may calculate the correction amount using not only the first thermal displacement amount (first value) but also the second thermal displacement amount (second value) within the predetermined period. .

(7) The program PG described above is for calculating the correction amount according to the thermal displacement in the predetermined axial direction in the machine tool 1. The control unit 300 (an example of a computer) includes A process of acquiring the axial position, which is the axial position of the slide portion at the time of detection, based on the detection, a process of acquiring the detected temperature detected by a temperature sensor provided at a predetermined location of the machine tool 1, and a calculation process for calculating a correction amount for correcting thermal displacement based on at least one of the acquired axial position and the detected temperature. In the calculation process, a first value indicative of the amount of thermal displacement is calculated based on a plurality of axial positions obtained during different detections, and a second value indicative of an estimated amount of thermal displacement is calculated based on the detected temperature. is calculated, the correction amount is calculated using the first value within a predetermined period from the start of machining of the workpiece W, and the correction amount is calculated using the second value after the predetermined period has elapsed.

(8) The correction amount calculation method for calculating the correction amount according to the thermal displacement in the predetermined axial direction in the machine tool 1 described above is based on the detection by the detection means of the axial direction of the slide portion at the time of detection. a step of acquiring an axial position that is a position; a step of acquiring a detected temperature detected by a temperature sensor provided at a predetermined location of the machine tool 1; and a calculating step of calculating a correction amount for correcting the thermal displacement. In the calculating step, a first value indicative of the amount of thermal displacement is calculated based on a plurality of axial positions obtained during different detections, and a second value indicative of an estimated amount of thermal displacement is calculated based on the detected temperature. is calculated, the correction amount is calculated using the first value within a predetermined period from the start of machining of the workpiece W, and the correction amount is calculated using the second value after the predetermined period has elapsed.

By using the correction amounts calculated by the configurations of (7) and (8) above, it is possible to satisfactorily correct the thermal displacement from the start of processing of the workpiece W, and also consider the thermal displacement occurring in the structure other than the slide portion. Displacement correction can be performed.

In the above description, descriptions of well-known technical matters are omitted as appropriate in order to facilitate understanding of the present invention.

DESCRIPTION OF SYMBOLS 1... Machine tool 2... Bed M1... 1st processing mechanism 10... 1st X-axis slide mechanism 20... Work holding part 30... 1st Z-axis slide mechanism 40... Tool moving mechanism 41... Fixing base 44... X-axis moving part 45... 1st 1 X-axis slide part 50 Y-axis moving part M2 Second processing mechanism 60 Fixing table 70 Work holding part 80 Second Z-axis slide mechanism 90 Second X-axis slide mechanism 100 Tool table 200 Detection mechanism Sp1 to Sp3 Detector D1 to D3 Dog St (St1 to St8) Temperature sensor 300 Control unit

Claims (6)

a slide portion that moves in a predetermined axial direction with respect to the base and adjusts the relative position in the axial direction between the workpiece gripped by the spindle and the tool for processing the workpiece;
a detection unit that is immovable with respect to the base and detects that the detection unit has come into contact with a dog provided on the slide unit or has approached the dog by a predetermined distance;
Based on the detection by the detection unit , an axial position, which is the position of the slide unit in the axial direction at the time of detection, is acquired, and at least the detected temperature detected by a temperature sensor provided at a location different from the slide unit is obtained. calculating means for calculating a correction amount for correcting the thermal displacement in the axial direction based on at least one of the acquired axial position and the detected temperature;
drive control means for moving the slide portion to a position obtained by adding the correction amount to the target position;
with
The calculation means is
A first value indicative of the amount of thermal displacement is calculated based on a plurality of axial positions obtained during different detections, and a second value indicative of an estimated amount of thermal displacement is calculated based on the detected temperature. death,
calculating the correction amount using the first value within a predetermined period from the start of machining the workpiece, and calculating the correction amount using the second value after the predetermined period has elapsed ;
the first value indicates an amount of the thermal displacement that changes over time within the predetermined period;
Machine Tools. further comprising a tool portion having a hollow portion through which a work can be passed, and the tool having a tip facing the hollow portion;
The tool portion is movable in the axial direction together with the slide portion,
The axial direction is the radial direction of the workpiece,
The dog and the detection portion are positioned outside the hollow portion in the axial direction,
A machine tool according to claim 1. a slide portion that moves in a predetermined axial direction with respect to the base and adjusts the relative position in the axial direction between the workpiece gripped by the spindle and the tool for processing the workpiece;
detection means for detecting that the movable portion that moves in the axial direction together with the sliding portion and the stationary portion that does not move in the axial direction come into contact with each other or approach each other by a predetermined distance;
Based on the detection by the detection means, the axial position, which is the axial position of the slide portion at the time of detection, is acquired, and the detected temperature detected by a temperature sensor provided at a predetermined location is acquired. calculation means for calculating a correction amount for correcting the thermal displacement in the axial direction based on at least one of the axial position and the detected temperature;
drive control means for moving the slide portion to a position obtained by adding the correction amount to the target position;
with
The calculation means is
A first value indicative of the amount of thermal displacement is calculated based on a plurality of axial positions obtained during different detections, and a second value indicative of an estimated amount of thermal displacement is calculated based on the detected temperature. death,
The correction amount is calculated using not only the first value but also the second value within a predetermined period from the start of machining of the workpiece, and the correction amount is calculated using the second value after the predetermined period has elapsed. calculate,
Machine Tools. The calculating means can set one period as the predetermined period from among a plurality of periods of different lengths prepared in advance,
A machine tool according to any one of claims 1 to 3. The calculation means can change the predetermined period according to a predetermined condition,
A machine tool according to any one of claims 1 to 4. A program for calculating a correction amount according to thermal displacement in the axial direction in the machine tool according to any one of claims 1 to 5 ,
causing a computer to function as the calculation means and the drive control means;
program.

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