JP2018001337A - Machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machine tool which improves machining accuracy by reducing the influence of thermal displacement in a measurement section.SOLUTION: A machine tool 1 includes: a workpiece holding section 40; a first reference section 51A; a tool holding section 62 which has a second reference section 62A facing the workpiece holding section; a support section 62X for movably supporting the tool holding section 62; a movement control section 751X for linearly moving the tool holding section 62 in a prescribed direction by driving the support section 62X; a probe 52 which has a first abutting section 522A and a second abutting section 523A; an output section 55 which outputs a signal according to the position of the probe 52 in the prescribed direction; and a probe movement amount calculation section 752 which calculates the movement amount of the probe 52 on the basis of the signal.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a machine tool.

  In a machine tool such as an NC lathe, heat generated in a drive unit such as a motor is transmitted to each part of the machine tool during operation, thereby causing structural deformation and distortion (thermal displacement) due to thermal expansion. As a result, during cutting, the tool tip may be sent to a position shifted from the original position with respect to the workpiece, which may reduce the processing accuracy.

  As a countermeasure against thermal displacement, for example, a tool correction method described in Patent Document 1 is known. In the tool correction method, the distance between the center axis holding the workpiece and the reference axis parallel to the center axis of the tool holding unit is detected, and the detection value is corrected according to the change in the latest detection value. Calculate the amount.

  As another countermeasure, a method of performing a warm-up operation before starting machining is known. The warm-up operation refers to bringing the machine tool into a state where machining can be performed with a desired accuracy by operating the machine tool until the thermal displacement due to the heat generated in the drive unit of the machine tool is sufficiently stabilized.

JP-A-56-134157

  However, in the tool correction method described in Patent Document 1, the following two errors due to heat occur in the measurement unit for detecting the distance between the center axis and the reference axis of the tool holding unit. One is an error due to the thermal expansion of the member constituting the measurement unit being different from the thermal expansion of the tool unit, and the other is an output error (temperature drift) of the detection circuit system due to thermal effects. Since these errors are included in the measurement value, an accurate correction value cannot be measured, and the processing accuracy is lowered.

  Further, in the method for performing the warm-up operation, not only the cost for the warm-up operation is generated, but also the substantial operation time of the machine tool is reduced due to the time required for the warm-up operation. Further, if the machine tool is stopped once, warm-up operation is required again when machining is resumed, so that the machine tool cannot be flexibly started and / or stopped.

  Accordingly, an object of the present invention is to provide a machine tool that can solve the above-described problems.

  Another object of the present invention is to provide a machine tool that can perform machining with high accuracy without performing warm-up operation.

  A machine tool according to the present invention has a workpiece holding portion for holding a workpiece rotatably, a first reference portion fixed to the workpiece holding portion, and a second reference portion facing the workpiece holding portion, and a tool A tool holding unit for holding the tool, a support unit for supporting the tool holding unit so as to be linearly movable in a predetermined direction orthogonal to the rotation axis of the workpiece, and a tool holding unit by driving the support unit. A movement control unit for linearly moving the first reference unit, a first contact unit for contacting the first reference unit, and a second contact unit for contacting the second reference unit. Based on the reference position data, the measuring element whose origin position is the position where the one abutting part is in contact with the first reference part, the output part that outputs a signal corresponding to the position of the measuring element in the predetermined direction, and the movement control part By moving the tool holder to a predetermined position, When the part moves the measuring element from the origin position to a position where the first contacting part and the first reference part are separated while the second reference part is in contact with the second contacting part, the amount of movement of the measuring element is And a measuring element movement amount calculation unit that calculates based on the signal.

  It is preferable that the machine tool according to the present invention further includes a workpiece origin correction unit that corrects the workpiece origin based on the calculated movement amount.

  In the machine tool according to the present invention, the interval between the second reference portion and the first reference portion relative to the interval between the rotation axis of the workpiece and the second reference portion in a predetermined direction when the tool holding portion is disposed at a predetermined position. The ratio is preferably set to be 0.1 to 15%.

  In the machine tool which concerns on this invention, it is preferable to further have the tool for processing a workpiece | work hold | maintained at the tool holding part.

  In the machine tool according to the present invention, it is preferable that the linear expansion coefficient of the workpiece holding portion and the linear expansion coefficient of the tool are set to be substantially the same.

  In the machine tool according to the present invention, it is preferable that the workpiece holding unit and the tool are made of the same base material.

  A workpiece origin correction method for a machine tool according to the present invention includes a workpiece holding portion for holding a workpiece rotatably, a first reference portion fixed to the workpiece holding portion, a tool for machining the workpiece, A tool holding unit having a second reference portion facing the workpiece holding unit and holding the tool, and a support for supporting the tool holding unit so as to be linearly movable in a predetermined direction perpendicular to the rotation axis of the workpiece. , A movement control unit for linearly moving the tool holding unit in a predetermined direction by driving the support unit, and a first contact unit and a second reference unit for contacting the first reference unit. A method for correcting the workpiece origin of a machine tool, comprising: a measuring element having a second abutting part for contact; and an output part for outputting a signal corresponding to the position of the measuring element in a predetermined direction. The origin position where the part contacts the first reference part And a step in which the movement control unit moves the tool holding unit to a predetermined position based on the reference position data, and a tool holding unit causes the second reference unit to abut against the second abutting unit. Moving from the origin position to a position where the first contact portion and the first reference portion are separated from each other, and calculating the movement amount of the probe based on the signal, and the workpiece origin based on the calculated movement amount. And a step of correcting.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the machine tool which can process with high precision, without performing a warming-up driving | operation every time it processes.

1 is a perspective view of a machine tool 1 according to the present invention. 1 is a partial front view of a machine tool 1. 1 is a partial plan view of a machine tool 1. 4 is a diagram for explaining a schematic configuration of a measurement unit 50. FIG. 3 is a diagram for explaining a schematic configuration of a control unit 70. FIG. It is a figure which shows an example of a probe position table. It is a figure which shows an example of the operation | movement flow of a measuring element reference | standard movement amount measurement process. It is a figure for demonstrating operation | movement of the machine tool 1 in a measuring element reference | standard movement amount measurement process. It is a figure which shows an example of the operation | movement flow of a workpiece | work origin correction process. It is a figure for demonstrating operation | movement of the machine tool 1 in a workpiece | work origin correction process. It is a figure which shows an example of the operation | movement flow of a cutting process. 1 is a schematic partial front view of a machine tool 1. FIG.

  Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, and extends to the invention described in the claims and equivalents thereof.

  FIG. 1 is a perspective view of a machine tool 1 according to the present invention, FIG. 2 is a partial front view of the machine tool 1, and FIG. 3 is a partial plan view of the machine tool 1. 1 to 3, an axis extending in the horizontal direction is an X axis, an axis extending in the vertical direction is a Y axis, and an axis orthogonal to the X axis and the Y axis is a Z axis.

  The machine tool 1 includes a bed 10, a spindle device 30, a guide bush device 40, a measurement unit 50, a tool device 60, a control unit 70, and a protective cover 80.

  The bed 10 is a metal substantially rectangular parallelepiped base. The bed 10 has a plane (XZ plane) substantially parallel to the X axis and the Z axis.

  The spindle device 30 includes a spindle stock 31, a spindle drive unit 31Z, a spindle 32, and a spindle drive unit 32A.

  The head stock 31 is a metal member supported by the head stock driving section 31Z so as to be movable along the Z-axis direction as indicated by an arrow S1 in FIG.

  The headstock drive unit 31Z includes metal rails LZ1 and LZ2 extending in the Z-axis direction, a ball screw BZ disposed between the rails LZ1 and LZ2, and extending in the Z-axis direction, and a non-rotating drive for rotating the ball screw BZ. The spindle head drive motor shown in the figure. The rails LZ1, LZ2 and the ball screw BZ are fixed on the XZ surface of the bed 10, respectively. Upon receiving a spindle head movement signal, which will be described later, the spindle head driving unit 31Z drives the spindle head driving motor to move the spindle head 31 along the Z-axis direction to a position corresponding to the spindle head movement signal.

  The main shaft 32 is a substantially cylindrical member made of metal that is rotatably supported around a rotation axis O extending in the Z-axis direction by the main shaft driving unit 32A. The main shaft 32 can hold a rod-shaped workpiece (workpiece) 2 along the rotation axis O.

  The spindle drive unit 32 </ b> A is a metal member fixed to the upper part of the spindle stock 31. The main shaft drive unit 32A has a main shaft drive motor (not shown) in which one end of the main shaft 32 is connected via a speed reducer (not shown). Upon receiving a spindle rotation instruction signal, which will be described later, the spindle driving unit 32A rotates the spindle 32 around the rotation axis O at a speed corresponding to the spindle rotation instruction signal.

  The guide bush device 40 includes a guide bush support 41, a guide bush 42, and a plate 43.

  The guide bush support 41 is a member made of cast iron as a base material, which is fixed on the XZ surface of the bed 10 on the + Z side of the headstock 31. Here, the base material refers to a material constituting a main part of a member or a part. The guide bush support 41 is formed with a through hole (not shown) having an axis line that coincides with the rotation axis O. The guide bush support body 41 functions as a work holding portion for holding the work 2 so as to be rotatable around the rotation axis O.

  The guide bush 42 is a substantially cylindrical member made of metal. A part of the guide bush 42 protrudes from the guide bush support 41 to the opposite side with respect to the headstock 31 and is fixed in a through hole formed in the guide bush support 41. The guide bush 42 is formed with a through hole having an axis that coincides with the rotation axis O. The guide bush 42 is inserted into the through hole so that the work 2 protrudes from the guide bush 42 to the opposite side to the headstock 31, and can rotate around the rotation axis O and move in the Z-axis direction. Can be held.

  The plate 43 is a member on a substantially metal plate fixed to the guide bush support 41 at the lower part of the guide bush 42.

  The measuring unit 50 includes a case 51 fixed to the guide bush support 41 via a plate 43 and a measuring element 52 partially accommodated in the case 51. A second abutting portion 523A for abutting against a slider 62 described later is formed at the + X side end portion of the measuring element 52. The configuration of the measurement unit 50 will be described later.

  The tool device 60 includes a support body 61, a slider 62, a slider driving unit 62 </ b> X, a tool post 63, a tool post driving unit 63 </ b> Y, and a tool 64.

  The support body 61 is a metal member fixed on the XZ surface of the bed 10 on the + X side of the guide bush support body 41. The support 61 has a plane (XY plane) parallel to the X axis and the Y axis.

  The slider 62 is a metal member supported by the slider drive unit 62X so as to be movable along the X-axis direction as indicated by an arrow S2 in FIGS. A contact surface 62 </ b> A for contacting the measuring element 52 is formed on the side of the slider 62 facing the measurement unit 50.

  The slider drive unit 62X includes metal rails LX1 and LX2 extending in the X-axis direction, a ball screw BX disposed between the rails LX1 and LX2, and extending in the X-axis direction, and not illustrated for rotationally driving the ball screw BX. And a slider drive motor. The rails LX1, LX2 and the ball screw BX are respectively fixed on the XY plane of the support body 61. When the slider drive unit 62X receives a slider movement signal described later, the slider drive unit 62X drives the slider drive motor to move the slider 62 along the X-axis direction to a position corresponding to the slider movement signal.

  The tool post 63 is a metal member supported by the tool post driving unit 63Y so as to be movable along the Y-axis direction as indicated by an arrow S3 in FIG.

  The tool post driving unit 63Y includes metal rails LY1 and LY2 extending in the Y-axis direction, a ball screw BY disposed between the rails LY1 and LY2 and extending in the Y-axis direction, and a non-rotating drive for rotating the ball screw BY. And a tool post driving motor shown in the figure. The rails LY1, LY2 and the ball screw BY are respectively fixed on the surface of the slider 62 opposite to the side engaged with the slider driving unit 62X. When the tool post driving unit 63Y receives a tool post movement signal described later, the tool post driving unit 63Y drives the tool post drive motor to move the tool post 63 along the Y-axis direction to a position corresponding to the tool post movement signal.

  The tool 64 is a substantially bar-shaped member whose base material is alloy tool steel fixed along the X-axis direction on the surface of the tool post 63 opposite to the side engaged with the tool post driving unit 63Y. . At the tip of the tool 64, an abutting portion 64A for processing the workpiece 2 by abutting against the workpiece 2 rotating around the rotation axis O is formed.

  The tool post driving unit 63Y, the tool post 63, and the tool 64 are fixed to the slider 62 in the X-axis direction. Therefore, the slider 62 functions as a tool holding unit for holding the tool 64. Further, the contact surface 62A functions as a second reference portion that faces the guide bush device 40 (work holding portion). The slider drive unit 62X functions as a support unit that supports the slider 62 (tool holding unit) so as to be movable in the X-axis direction orthogonal to the rotation axis O that is the rotation axis of the workpiece 2.

  The control unit 70 is a member fixed on the XZ surface of the bed 10 on the + X side of the head stock 31. The configuration of the control unit 70 will be described later.

  The protective cover 80 is a metal substantially rectangular parallelepiped casing. The protective cover 80 covers a part of the machine tool 1 so as to protect it from the outside. In addition, in the figure shown in FIG. 1, the protective cover 80 is represented as a permeation | transmission figure.

  FIG. 4 is a diagram for explaining a schematic configuration of the measurement unit 50. The coordinate system of the measurement unit 50 is an X ′ axis that is opposite to the X axis.

  The measurement unit 50 includes a case 51, a probe 52, a spring 53, a coil 54, and a current amplitude signal processing unit 55. In addition, in the figure shown in FIG. 4, case 51 and measuring element 52 are typically represented with sectional drawing.

  The case 51 is a substantially cylindrical and hollow member made of metal having an axis extending in the X′-axis direction. The case 51 passes through the plate 43 and is screwed to the guide bush support 41 at positions N1 and N2 close to the end on the −X ′ side. An opening 51 </ b> B is formed at the end of the case 51 on the −X ′ side. A contact surface 51 </ b> A for contacting the measuring element 52 is formed on the inner surface of the end portion of the case 51 where the opening 51 </ b> B is formed. The contact surface 51A functions as a first reference portion fixed to the guide bush device 40 (work holding portion). The positions on the X ′ axis of the contact surface 51A and the screwing positions N1 and N2 with respect to the guide bush support 41 are substantially the same.

  The probe 52 is a substantially bar-like member that is slidably held in the X-axis direction inside the case 51. The probe 52 has a base 521, a flange 522, and an end 523.

  The base 521 is a substantially bar-shaped metal member having an axis extending in the X-axis direction. On the surface of the base 521, a core 521A made of a ferromagnetic material having a predetermined thickness is formed from the end on the + X ′ side of the base 521 over a predetermined length.

  The flange portion 522 is a substantially disk-shaped member that is provided on the −X ′ side of the base portion 521 and has a larger diameter than the opening portion 51 </ b> B of the case 51. The collar portion 522 is made of the same material as the base portion 521. A first contact portion 522A for contacting the contact surface 51A (first reference portion) of the case 51 is formed on the surface of the flange portion 522 that faces the opening 51B.

  The end 523 is a substantially conical member made of the same material as the base 521 provided on the −X ′ side of the flange 522. The end portion 523 protrudes from the opening 51B to the outside of the case 51. A second contact portion 523A for contacting the contact surface 62A (second reference portion) of the slider 62 is formed at the tip of the end portion 523 on the −X ′ side.

  Here, the position of the probe on the X′-axis of the first contact portion 522A of the probe 52 when the position of the contact surface 51A of the case 51 is the origin (represented by D in FIG. 4). Position). Further, the position of the measuring element origin is set to the position of the measuring element 52 in a state where the first contact portion 522A of the flange portion 522 is in contact with the contact surface 51A of the case 51.

  The spring 53 has one end fixed to the end of the case 51 opposite to the opening 51 </ b> B and the other end fixed to the + X ′ side end of the base 521 of the probe 52, and elastically in the X-axis direction. This is a displaceable metal spring member. The spring 53 urges the measuring element 52 in the direction indicated by the arrow F so that the measuring element 52 is disposed at the measuring element origin position.

  The coil 54 is a metal coil member wound around the core 521 </ b> A formed on the probe 52. The coil 54 is connected to an AC voltage source (not shown) and a current amplitude signal processing unit 55. A coil current corresponding to a predetermined AC voltage supplied from an AC voltage source flows through the coil 54. The coil current is output to the current amplitude signal processing unit 55. The amplitude of the coil current changes linearly according to the probe position.

  The current amplitude signal processing unit 55 is an electric circuit connected to the coil 54. The current amplitude signal processing unit 55 generates a current amplitude signal based on the coil current output from the coil 54. Here, the current amplitude signal is a signal indicating the amplitude of the coil current corresponding to the probe position. The current amplitude signal processing unit 55 outputs the generated current amplitude signal to the control unit 70.

  The measuring unit 50 is not limited to the one described above, and may have other configurations such as a capacitance type and an optical type as long as a signal corresponding to the position of the object to be measured can be output.

  FIG. 5 is a diagram for explaining a schematic configuration of the control unit 70.

  The control unit 70 includes a communication unit 71, a storage unit 72, an operation unit 73, a display unit 74, and a processing unit 75.

  The communication unit 71 includes a communication circuit, and connects the control unit 70 to the spindle drive unit 32A, the spindle drive unit 31Z, the slider drive unit 62X, the tool post drive unit 63Y, and the measurement unit 50. The communication unit 71 transmits the command supplied from the processing unit 75 to the spindle drive unit 32A, the spindle drive unit 31Z, the slider drive unit 62X, the tool post drive unit 63Y, and the measurement unit 50. Further, the communication unit 71 supplies data received from the spindle driving unit 32A, the spindle head driving unit 31Z, the slider driving unit 62X, the tool post driving unit 63Y, and the measurement unit 50 to the processing unit 75.

  The storage unit 72 includes, for example, a semiconductor memory. The storage unit 72 stores a driver program, an operating system program, an application program, data, and the like used for processing in the processing unit 75. The storage unit 72 stores, as an application program, a program for measuring element reference movement measurement processing, a program for workpiece origin correction processing, a program for cutting processing, and the like. The storage unit 72 stores, as data, the workpiece origin (the position of the center of the workpiece with respect to the machine coordinate system of the machine tool 1) and a probe position table to be described later. The computer program is stored in the storage unit 72 from a computer-readable portable recording medium such as a CD-ROM (compact disk read only memory) or a DVD-ROM (digital versatile disk read only memory) using a known setup program. May be installed. The storage unit 72 may temporarily store temporary data related to a predetermined process.

  The operation unit 73 may be any device as long as the operation of the control unit 70 is possible. For example, the operation unit 73 is a touch panel type input device, a keypad, or the like. The user can input letters, numbers, and the like using this device. The operation unit 73 receives a user instruction, generates a signal corresponding to the received instruction, and outputs the signal to the processing unit 75.

  The display unit 74 may be any device as long as it can output a moving image, a still image, and the like, for example, a touch panel display device, a liquid crystal display, an organic EL (Electro-Luminescence) display, or the like. The display unit 74 displays a moving image corresponding to the moving image data supplied from the processing unit 75, a still image corresponding to the still image data, and the like.

  The processing unit 75 includes one or a plurality of processors and their peripheral circuits. The processing unit 75 comprehensively controls the overall operation of the control unit 70, and is, for example, a CPU (Central Processing Unit). The processing unit 75 includes a communication unit 71, a display unit 74, and the like so that various processes of the control unit 70 are executed in an appropriate procedure according to a program stored in the storage unit 72, an operation of the operation unit 73, and the like. Control the behavior. The processing unit 75 executes processing based on programs (driver program, operating system program, application program, etc.) stored in the storage unit 72.

  The processing unit 75 includes a control unit 751, a probe moving amount calculation unit 752, and a work origin correction unit 753. Each of these units included in the processing unit 75 is a functional module implemented by a program executed on a processor included in the processing unit 75. Alternatively, each of these units included in the processing unit 75 may be implemented in the control unit 70 as an independent integrated circuit, a microprocessor, or firmware.

  The control unit 751 includes a spindle control unit 751A, a slider control unit 751X, a tool post control unit 751Y, and a spindle table control unit 751Z.

  The main shaft control unit 751A transmits a main shaft rotation instruction signal for rotating the main shaft 32 around the rotation axis O at a predetermined speed to the main shaft driving unit 32A.

  The slider control unit 751X transmits a slider movement instruction signal for moving the slider 62 to a predetermined position along the X-axis direction to the slider driving unit 62X. The slider control unit 751X functions as a movement control unit for linearly moving the slider drive unit (support unit) along the X-axis direction.

  The tool post control unit 751Y transmits a tool post movement instruction signal for moving the tool post 63 to a predetermined position along the Y-axis direction to the tool post driving unit 63Y.

  The headstock controller 751Z transmits a headstock movement instruction signal for moving the headstock 31 to a predetermined position along the Z-axis direction to the headstock drive unit 31Z.

  The tracing stylus movement amount calculation unit 752 includes a table update unit 752A and a position acquisition unit 752B.

  The table update unit 752A updates the probe position table stored in the storage unit 72 based on the current amplitude signal included in the probe position table.

  The position acquisition unit 752B refers to the probe position table stored in the storage unit 72, and acquires a probe position corresponding to the amplitude of the coil current indicated by the current amplitude signal.

  The workpiece origin correction unit 753 calculates a thermal displacement amount from the reference element movement amount and the tracing element movement amount, calculates a workpiece origin shift amount based on the calculated thermal displacement amount, and is stored in the storage unit 72. Correct the workpiece origin.

  FIG. 6 is a diagram illustrating an example of a probe position table stored in the storage unit 72.

  The probe position table is a table for associating the probe position with the amplitude of the coil current corresponding to the current amplitude signal.

  The first column of the probe position table represents the probe position. However, the unit is micrometer (μm).

  The second column of the probe position table represents the amplitude of the coil current corresponding to the probe position. However, the unit is ampere (A).

  When the probe position is 0 (μm), the amplitude of the coil current is I (A). When the probe position is D (μm) (D is an integer of 1 or more), the amplitude of the coil current is I + D · ΔI (A). Here, ΔI is the amount of change in the amplitude of the coil current when the probe position changes by 1 μm. ΔI is a constant determined by the characteristics of the measurement unit 50 and can be measured in advance using the measurement unit 50.

  FIG. 7 is a diagram illustrating an example of an operation flow of the probe reference movement amount measurement process, and FIG. 8 is a diagram for explaining the operation of the machine tool 1 in the probe reference movement amount measurement process. In FIG. 8, for convenience of explanation, the measurement unit 50, the slider 62, and the tool 64 are schematically shown with their dimensions exaggerated and partially omitted.

  The probe reference movement amount measurement process is executed mainly by the control unit 70 in cooperation with each element of each device based on the program of the probe reference movement amount measurement process stored in the storage unit 72.

  First, warm-up operation processing is performed (S100). In the warm-up operation process, the main shaft drive unit 32A rotates the main shaft 32 around the rotation axis O according to the main shaft rotation instruction signal received from the main shaft control unit 751A for a predetermined time. In the warm-up operation process, the slider drive unit 62X moves the slider 62 along the X-axis direction in accordance with the slider movement instruction signal received from the slider control unit 751X for a predetermined time.

  In the warm-up operation process, the tool post driving unit 63Y moves the tool post 63 along the Y-axis direction in accordance with the tool post movement instruction signal received from the tool post control unit 751Y for a predetermined time. In the warm-up operation process, the headstock driving unit 31Z moves the headstock 31 along the Z-axis direction in accordance with the head stock movement instruction signal received from the head stock control unit 751Z for a predetermined time.

  The thermal displacement of the machine tool 1 is stabilized by the warm-up operation process, and the machine tool 1 is in a state where the machining can be performed with a desired accuracy. When the warm-up operation process is completed, the tool post 63 is arranged so that the contact portion 64A coincides with the rotation axis O on the Y axis.

  Next, the slider control unit 751X transmits a slider movement instruction signal for moving the slider 62 to the + X side end of the slider driving unit 62X to the slider driving unit 62X (S101).

Next, when the slider drive unit 62X receives the slider movement instruction signal, the slider drive unit 62X moves the slider 62 along the X-axis direction to the + X side end of the slider drive unit 62X based on the received slider movement instruction signal ( S102). At this time, as shown in FIG. 8A, the probe 52 is disposed at the probe origin position, and the first contact portion 522A of the flange 522 is positioned on the X ′ axis by the urging force of the spring 53. At “T ₀ ”, the state comes into contact with the contact surface 51 A of the case 51.

  Next, the slider driving unit 62X transmits a signal indicating that the movement of the slider 62 is completed to the control unit 70 (S103).

Next, when the table update unit 752A receives a signal indicating that the movement of the slider 62 is completed from the slider drive unit 62X via the communication unit 71, the table update unit 752A receives the current amplitude signal s1 output from the current amplitude signal processing unit 55. Obtained via the communication unit 71 (S104). Here, the amplitude of the coil current indicated by the current amplitude signal s1 is “I ₁ ”.

Next, when the table updating unit 752A acquires the current amplitude signal s1 via the communication unit 71, the table updating unit 752A updates the probe position table stored in the storage unit 72 based on the acquired current amplitude signal s1 (S105). Specifically, the table updating unit 752A rewrites the amplitude “I” of the coil current included in the probe position table to the amplitude “I ₁ ” of the coil current indicated by the received current amplitude signal s1. By updating the probe position table, the position “T ₀ ” on the X ′ axis shown in FIG. 8A becomes the new probe origin “0”.

  Next, the table update unit 752A transmits a signal indicating that the update of the probe position table is completed to the slider control unit 751X (S106).

Next, the slider control portion 751X receives a signal indicating that the updating of the probe position table has been completed, slider movement for moving the slider 62 to a position where the abutting portion 64A is placed at the reference position O _M An instruction signal is transmitted to the slider drive unit 62X (S107). Here, the reference position O _M is arranged at a predetermined distance from the rotation axis O of the workpiece 2 to the −X side (+ X ′ side).

  Next, upon receiving the slider movement instruction signal, the slider drive unit 62X moves the slider 62 along the X-axis direction by the movement amount indicated by the received slider movement instruction signal (S108).

At this time, since the machine tool 1 is in a state capable of machining with a desired accuracy by the warm-up operation process (S100), the contact portion 64A of the tool 64 is at the reference position O as shown in FIG. It is arranged in _M (position “P ₁ ” on the X ′ axis).

At this time, the slider 62 causes the contact 52 to contact the first contact portion 522A and the case from the contact point origin position while bringing the contact surface 62A (second reference portion) into contact with the second contact portion 523A. It is moved to a position “T ₁ ” on the X ′ axis at which the contact surface 51A of 51 is separated.

  Next, the slider driving unit 62X transmits a signal indicating that the movement of the slider 62 is completed to the control unit 70 (S109).

Next, when the position acquisition unit 752B receives a signal indicating that the movement of the slider 62 is completed from the slider driving unit 62X via the communication unit 71, the position acquisition unit 752B receives the current amplitude signal s2 output from the current amplitude signal processing unit 55. Obtained via the communication unit 71 (S110). Here, the amplitude of the coil current indicated by the current amplitude signal s2 is “I ₂ ”.

Next, when the position acquisition unit 752B acquires the current amplitude signal s2 via the communication unit 71, the position acquisition unit 752B refers to the probe position table stored in the storage unit 72, and obtains the coil current indicated by the acquired current amplitude signal s2. A probe position “T ₁ ” corresponding to the amplitude “I ₂ ” is acquired (S111).

Next, the position acquisition unit 752B stores the acquired probe position “T ₁ ” in the storage unit 72 as the probe reference movement amount t1 (S112), and the measurement element reference movement amount measurement process ends.

  FIG. 9 is a diagram illustrating an example of the operation flow of the workpiece origin correction process, and FIG. 10 is a diagram for explaining the operation of the machine tool 1 in the workpiece origin correction process. In FIG. 10, for convenience of explanation, the measurement unit 50, the slider 62, and the tool 64 are schematically shown with dimensions exaggerated and partially omitted.

  The workpiece origin correction process is performed at an arbitrary time after the stylus reference movement amount measurement process, based on a workpiece origin correction process program stored in the storage unit 72, mainly by the control unit 70 in cooperation with each element of each device. And executed.

  The tool post 63 is arranged in advance so that the contact portion 64A coincides with the rotation axis O on the Y axis.

  First, the slider control unit 751X transmits a slider movement instruction signal for moving the slider 62 to the + X side end of the slider driving unit 62X to the slider driving unit 62X (S200).

Next, when the slider drive unit 62X receives the slider movement instruction signal, the slider drive unit 62X moves the slider 62 along the X-axis direction to the + X side end of the slider drive unit 62X based on the received slider movement instruction signal ( S201). At this time, as shown in FIG. 10A, the probe 52 is arranged at the probe origin position, and the first contact portion 522A of the flange 522 is positioned on the X ′ axis by the urging force of the spring 53. At “T ₀ ”, the state comes into contact with the contact surface 51 A of the case 51.

  Next, the slider drive unit 62X transmits a signal indicating that the movement of the slider 62 is completed to the control unit 70 (S202).

Next, when the table updating unit 752A receives a signal indicating that the movement of the slider 62 is completed from the slider driving unit 62X via the communication unit 71, the table updating unit 752A receives the current amplitude signal s3 output from the current amplitude signal processing unit 55. Obtained via the communication unit 71 (S203). Here, the amplitude of the coil current indicated by the current amplitude signal s3 is “I ₃ ”.

Next, when the table update unit 752A acquires the current amplitude signal via the communication unit 71, the table update unit 752A updates the probe position table stored in the storage unit 72 based on the acquired current amplitude signal s3 (S204). Specifically, the table updating unit 752A rewrites the amplitude “I ₁ ” of the coil current included in the probe position table to the amplitude “I ₃ ” of the coil current indicated by the received current amplitude signal s3. By updating the probe position table, the position “T ₀ ” on the X ′ axis shown in FIG. 10A becomes the new probe origin “0”.

  Next, the table update unit 752A transmits a signal indicating that the update of the probe position table is completed to the slider control unit 751X (S205).

Next, the slider control portion 751X receives a signal indicating that the updating of the probe position table has been completed, slider movement for moving the slider 62 to a position where the abutting portion 64A is placed at the reference position O _M An instruction signal is transmitted to the slider drive unit 62X (S206).

  Next, upon receiving the slider movement instruction signal, the slider drive unit 62X moves the slider 62 along the X-axis direction by the movement amount indicated by the received slider movement instruction signal (S207).

At this time, as shown in FIG. 10 (b), the slider 62 is placed in a position different from the position shown in FIG. 8 (b) by thermal displacement, the abutting portion 64A is the reference position O _M of the tool 64 They are arranged at different positions (position “P ₂ ” on the X ′ axis).

At this time, the slider 62 causes the contact 52 to contact the first contact portion 522A and the case from the contact point origin position while bringing the contact surface 62A (second reference portion) into contact with the second contact portion 523A. The contact surface 51A of the 51 is moved to the position “T ₂ ” on the X ′ axis where the contact surface 51A is separated.

  Next, the slider drive unit 62X transmits a signal indicating that the movement of the slider 62 is completed to the control unit 70 (S208).

Next, when the position acquisition unit 752B receives a signal indicating that the movement of the slider 62 is completed from the slider driving unit 62X via the communication unit 71, the position acquisition unit 752B receives the current amplitude signal s4 output from the current amplitude signal processing unit 55. Obtained via the communication unit 71 (S209). Here, the amplitude of the coil current indicated by the current amplitude signal s4 is “I ₄ ”.

Next, when the position acquisition unit 752B acquires the current amplitude signal s4 via the communication unit 71, the position acquisition unit 752B refers to the probe position table stored in the storage unit 72, and obtains the coil current indicated by the acquired current amplitude signal s4. A probe position “T ₂ ” corresponding to the amplitude “I ₄ ” is acquired (S210).

Next, the position acquisition unit 752B stores the acquired probe position “T ₂ ” in the storage unit 72 as the probe movement amount t2 (S211).

Next, when the position acquisition unit 752B stores the probe movement amount t2 in the storage unit 72, the position acquisition unit 752B transmits a signal indicating that the storage of the probe position “T ₂ ” is completed to the workpiece origin correction unit 753 (S212). ).

  Next, when the workpiece origin correction unit 753 receives a signal indicating that the storage of the probe movement amount t2 is completed, the workpiece origin correction unit 753 stores the movement amount t2 as the thermal displacement amount Δt in the storage unit 72 in S112 described above. A difference (t2−t1) from the measured probe reference movement amount t1 is calculated (S213).

  Next, the workpiece origin correction unit 753 calculates a shift amount of the workpiece origin based on the calculated thermal displacement amount Δt (= t2−t1), and corrects the workpiece origin stored in the storage unit 72. (S214). Specifically, the workpiece origin correction unit 753 rewrites the workpiece origin stored in the storage unit 72 to a value obtained by adding the value of the thermal displacement amount Δt to the value. At this time, in a machine tool that employs a diameter value in the coordinate system, if the value of Δt that is measured is added as it is, it will be treated as a radius value, so that it is added after conversion to a diameter value (ie, Δt X2 is added to the workpiece origin). Thus, the work origin correction process is completed.

  FIG. 11 is a diagram illustrating an example of an operation flow of the cutting process.

  The cutting process is executed mainly by the control unit 70 in cooperation with each element of each device based on the cutting process program stored in the storage unit 72.

  It is assumed that the workpiece 2 is previously held by the main shaft 32 along the rotation axis O, is inserted into the guide bush support body 41 and the guide bush 42, and protrudes from the guide bush 42 to the + Z side.

  First, a cutting process is performed (S400). In the cutting process, the slider 62 moves along the X-axis direction, the tool post 63 moves along the Y-axis direction, and the headstock 31 moves along the Z-axis direction by a predetermined amount of movement at predetermined timings. As a result, the contact portion 64A of the tool 64 contacts the workpiece 2 rotating around the rotation axis O, so that the workpiece 2 is cut to a desired dimension.

  Next, a cut-off process is performed (S401). In the parting-off process, the headstock 31 moves by a predetermined amount of movement in the Z-axis direction, so that the parting-off position of the workpiece 2 coincides with the tool 64 in the Z-axis direction, and the contact portion 64A of the tool 64 is disposed on the rotation axis O. The slider 62 moves along the X-axis direction until it is done. As a result, the portion of the workpiece 2 that has been subjected to the cutting process is separated from the remaining portion. This completes the cutting process.

  FIG. 12 is a schematic partial front view of the machine tool 1.

  With reference to FIG. 12, it will be described that the machine tool 1 can perform machining with high accuracy without performing warm-up operation. In FIG. 12, the dimensions of each part of the machine tool 1, for example, the guide bush support 41, the slider 62, the tool 64, and the measurement unit 50 are exaggerated so that their relative positional relationship is clear. It is schematically described. In the following description, “position” means “position on the X′-axis” unless otherwise specified.

The state of the machine tool 1 in FIG. 12 is the same as the state of FIG. As shown in FIG. 12, the position of the reference position O _M is P ₁ , the position of the contact surface 51 A of the case 51 is T ₀ , and the position of the contact surface 62 A of the slider 62 is R. The tool 64 is fixed to the slider 62 at the position R, and the case 51 of the measuring unit 50 is fixed to the guide bush support 41 at the position T ₀ .

Portion protruding from the contact surface 62A + X 'side of the tool 64 includes a portion L1 from the position P ₁ of the reference position O _M to the position T ₀ of the contact surface 51A of the case 51, the abutment surface of the case 51 It is divided into a portion L2 from the position T _{0 of} 51A to the position R of the contact surface 62A of the slider 62. Further, a portion between the position P ₁ and the position T ₀ of the guide bush support 41 is defined as a portion L3. Further, a portion between the position T ₀ and the position R of the probe 52 is defined as a portion L4.

  The base material of the tool 64 and the guide bush support 41 has substantially the same linear expansion coefficient. For example, the base material of the tool 64 is alloy tool steel, and the base material of the guide bush support 41 is cast iron. Therefore, the rate at which the portion L1 of the tool 64 expands or contracts is substantially equal to the rate at which the portion L3 of the guide bush support 41 expands or contracts. Therefore, the thermal displacement of the part L1 of the tool 64 and the thermal displacement of the part L3 of the guide bush support body 41 are canceled with each other.

In the machine tool 1, the deviation from the reference position O _M of the contact portion 64A of the tool 64 caused by thermal displacement is determined by measuring the position of the second reference portion. Here, the used position shift amount of the second reference portion (t2-t1) as the amount of deviation from the reference position O _M of the contact portion 64A of the tool 64, should the relationship L1 + L2 = L3 + L4 is satisfied is there. First, since L1 and L3 have substantially the same linear expansion coefficient, L1 = L3.

  Next, the relationship between L2 and L4 will be examined. As the material of the probe 52, carbide or the like is used according to demands such as durability. Therefore, L2 and L4 have different linear expansion coefficients. However, by setting the dimension of L4 to L1 + L2 sufficiently small, the difference in thermal expansion between L2 and L4 becomes negligible.

From the above, it can be regarded as substantially the same thermal expansion amount of L1 + L2 and L3 + L4, the positional displacement amount of the second reference portion can be treated as a deviation amount from the reference position O _M of the contact portion 64A of the tool 64 .

  In order to secure processing with higher accuracy, the ratio of L4 / (L1 + L2) is preferably 15% or less. Further, in order to sufficiently secure the stroke length of the probe 52 in the measuring unit 50, the ratio of L4 / (L1 + L2) is preferably set to 0.1% or more.

It is also possible to determine the dimension value of L4 from an allowable error. For example, it is assumed that the tool is S45C (linear expansion coefficient 11.2 × 10 ⁻⁶ / ° C.) and the probe is carbide (linear expansion coefficient 5.5 × 10 ⁻⁶ / ° C.). At this time, in a machine tool whose temperature change due to operation is 40 ° C., if the allowable difference in thermal expansion amount of L4 relative to L2 is 0.6 μm, L4 is determined to be 2.6 mm.

Thus, the machine tool 1 (without become a state after the warm-up operation) without becoming a thermal equilibrium state, from the position P ₁ of the reference position O _M of the contact surface 62A of the slider 62 It is possible to accurately grasp the distance to the position R. In other words, it is possible to accurately control the position of the contact portion 64A of the tool 64 even if the machine tool 1 is not in a thermal equilibrium state (not in a state after the warm-up operation). Become. Therefore, the machine tool 1 can perform machining with high accuracy without performing warm-up operation.

  In addition, the base material of the tool 64 and the guide bush support body 41 may be the same. In this case, the influence of the thermal displacement difference between the tool 64 and the guide bush support 41 on the measurement value of the moving amount of the probe is further reduced, and the machining accuracy of the machine tool 1 is further improved.

The setting of the linear expansion coefficient between the tool and the guide bush support is substantially the same as follows. The difference in coefficient of linear expansion between the tool and the guide bush support is preferably set in consideration of the influence on the measured value. For example, in a machine tool in which L1 (= L3) is 50 mm and the temperature change due to operation is 40 ° C., when the difference in allowable thermal expansion between L1 and L3 is 0.6 μm, the tool and guide bush support The difference in thermal expansion coefficient is set within 0.3 × 10 ⁻⁶ / ° C.

  In the machine tool 1, the probe movement amount calculation unit 752 calculates the movement amount from the table update unit 752 </ b> A for using the state in which the probe 52 is arranged at the probe origin position as a reference, and the movement amount from the reference position. The position acquisition unit 752B is provided. However, the probe movement amount calculation unit 752 may not include the table update unit 752A. At this time, the position acquisition unit 752B refers to the probe position table, acquires the probe position in the state where the probe is arranged at the probe origin position and the moved probe position, and compares the positions of the two probe positions. The difference may be calculated as the movement amount.

  In the above-described probe reference movement amount measurement process, the warm-up operation process is performed (S100). However, step S100 may be omitted if the machine tool 1 is capable of machining with a desired accuracy. Whether or not the machine tool 1 can perform machining with a desired accuracy can be confirmed by measuring, for example, the dimensions of a finished product produced by the cutting process by the machine tool 1.

  In the above-described probe reference movement measurement process or workpiece origin correction process, the current amplitude signal s1 or s3 is acquired with the slider 62 disposed at the + X side end of the slider drive unit 62X (S102, S201). (S104, S203). However, the current amplitude signal s1 or s3 may be acquired in a state where the slider 62 is disposed at an arbitrary position from the + X side end of the slider driving unit 62X to a position where the slider 62 starts to contact the measuring element 52. Here, the position at which the slider 62 starts to contact the measuring element 52 refers to the first contacting part 522A of the measuring element 52 contacting the contacting surface 51A of the case 51 and the second contacting part of the measuring element 52. This is the position where 523A is in contact with the contact surface 62A of the slider 62. As the position of the slider 62 when the current amplitude signal s1 or s3 is acquired is closer to the measuring element 52, the influence of the temperature drift of the measuring unit 50 on the measurement value can be further reduced.

  In the above-described stylus reference movement amount measurement process, when the warm-up operation process (S100) is completed, the tool post 63 is arranged so that the contact portion 64A coincides with the rotation axis O on the Y axis. did. However, the present invention is not limited to this, and the tool post 63 may be disposed at an arbitrary position where the contact portion 64A does not coincide with the rotation axis O on the Y axis.

  In the workpiece origin correction process described above, it is assumed that the tool post 63 is arranged in advance so that the contact portion 64A coincides with the rotation axis O on the Y axis immediately before S200. However, the present invention is not limited to this, and the tool post 63 may be disposed at an arbitrary position where the contact portion 64A does not coincide with the rotation axis O on the Y axis.

In feeler reference movement amount above measurement processing and the workpiece origin correction processing, the reference position O _M was assumed to be located at a position a predetermined distance of the work 2 from the rotational axis O in the -X side (+ X 'side). However, the reference position O _M will, to the extent and the second contact portion 523A comes into contact with the contact surface 62A of the slider 62 first abutment portion 522A does not contact the contact surface 51A of the case 51, the tool 64 You may set in the arbitrary positions which can match | combine the contact part 64A.

DESCRIPTION OF SYMBOLS 1 Machine tool 2 Work 10 Bed 30 Spindle device 31 Spindle base 31Z Spindle base drive part 32 Spindle 32A Spindle drive part 40 Guide bush apparatus (work holding part)
41 Guide Bush Support 42 Guide Bush 43 Plate 50 Measurement Unit 51 Case 51A Contact Surface (First Reference Unit)
51B Opening 52 Measuring Element 521 Base 521A Core 522 Gutter 522A First Abutment 523 End 523A Second Abutment 53 Spring 54 Coil 55 Current Amplitude Signal Processing Unit 60 Tool Device 61 Support 62 Slider (Tool Holding Unit) )
62A Contact surface (second reference part)
62X Slider driving part (supporting part)
63 Tool post 63Y Tool post drive part 64 Tool 64A Contact part 70 Control part 71 Communication part 72 Storage part 73 Operation part 74 Display part 75 Processing part 751 Control part 751A Spindle control part 751X Slider control part (movement control part)
751Y Turret control unit 751Z Headstock control unit 752 Probe movement amount calculation unit 752A Table update unit 752B Position acquisition unit 753 Work origin correction unit 80 Protective cover

Claims (7)

A workpiece holder for holding the workpiece rotatably;
A first reference part fixed to the work holding part;
A tool holding part for holding a tool for processing the workpiece, the second reference part facing the work holding part;
A support portion for supporting the tool holding portion so as to be linearly movable in a predetermined direction orthogonal to the rotation axis of the workpiece;
A movement control unit for linearly moving the tool holding unit in the predetermined direction by driving the support unit;
A first contact portion for contacting the first reference portion; and a second contact portion for contacting the second reference portion, wherein the first contact portion contacts the first reference portion. A probe with the position taken as the origin position,
An output unit that outputs a signal corresponding to the position of the measuring element in the predetermined direction;
The movement control unit moves the tool holding unit to a predetermined position based on reference position data, so that the tool holding unit causes the second reference unit to abut on the second abutting unit while moving the measuring element. A measuring element movement amount calculation unit that calculates a movement amount of the measuring element based on the signal when the first contact part and the first reference part are moved away from the origin position A machine tool characterized by having a machine tool.   The machine tool according to claim 1, further comprising a workpiece origin correction unit that corrects the workpiece origin according to the calculated movement amount.   Ratio of the interval between the second reference portion and the first reference portion with respect to the interval between the rotation axis of the workpiece and the second reference portion in the predetermined direction when the tool holding portion is disposed at the predetermined position. Is set to be 0.1 to 15%, the machine tool according to claim 1 or 2.   The machine tool according to any one of claims 1 to 3, further comprising a tool that is held by the tool holding unit and that is used to process the workpiece.   The machine tool according to any one of claims 1 to 4, wherein a linear expansion coefficient of the workpiece holding unit and a linear expansion coefficient of a tool for processing the workpiece are set to be substantially the same.   The machine tool according to any one of claims 1 to 4, wherein the workpiece holding unit and the tool for machining the workpiece are configured of the same base material. A workpiece holding portion for holding the workpiece rotatably; a first reference portion fixed to the workpiece holding portion; a tool for processing the workpiece; and a second reference portion facing the workpiece holding portion. And a tool holding portion for holding the tool, a support portion for supporting the tool holding portion so as to be linearly movable in a predetermined direction perpendicular to the rotation axis of the workpiece, and driving the support portion. A movement control unit for linearly moving the tool holding unit in the predetermined direction, a second contact unit for contacting the first reference unit and a second contact unit for contacting the first reference unit A measuring element having an abutting part; and an output part for outputting a signal corresponding to the position of the measuring element in the predetermined direction;
A method of correcting the workpiece origin of a machine tool having
Detecting an origin position where the first contact portion is in contact with the first reference portion;
The movement control unit moving the tool holding unit to a predetermined position based on reference position data;
The tool holding portion moves the measuring element from the origin position to a position where the first contact portion and the first reference portion are separated from each other while the second reference portion is in contact with the second contact portion. And calculating the amount of movement of the probe based on the signal;
Correcting the workpiece origin based on the calculated amount of movement;
A method for correcting the workpiece origin of a machine tool, comprising:

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