Machine tool

Abstract

The machine tool includes: a movable object (30); a linear guide (51) that includes a guide rail (61) and a slider (65) attached to the movable object (30) and slidable along the guide rail (61), and is configured to guide the movable object (30) in a moving direction thereof; and a temperature sensor (81) that is provided in the slider (65) and is configured to detect a temperature of the slider (65).

Description

MACHINE TOOL

[0001] The present invention relates to a machine tool.

[0002] For example, Japanese Patent Laying-Open No. 2013-234978 (PTL 1) discloses a machine tool that includes a column provided on a bed, a spindle head having a spindle, and a saddle having a table. The spindle head is supported on a front surface of the column, and is movable in the vertical direction (Z axis direction). The saddle is movable back and forth in the horizontal direction (Y axis direction), and is provided with a table. The table is movable leftward and rightward in the horizontal direction (X axis direction).

[0003] PTL 1: Japanese Patent Laying-Open No. 2013-234978

[0004] As disclosed in PTL 1 mentioned above, it is known that the machine tool includes a movable object which is movable in linear directions. In such a machine tool, in order to further improve the machining accuracy of a workpiece, it is required to position the movable object with higher accuracy to a target movement position defined by a NC program.

[0005] An object of the present invention is to provide a machine tool capable of positioning a movable object with higher accuracy to a target movement position.

[0006] A machine tool according to one aspect of the present invention includes: a movable object; a linear guide that includes a guide rail and a slider attached to the movable object and slidable along the guide rail, and is configured to guide the movable object in a moving direction thereof; and a temperature sensor that is provided in the slider and is configured to detect a temperature of the slider.

[0007] A machine tool according to another aspect of the present invention includes: a base; a movable object movable relative to the base; a linear guide that includes a guide rail and a slider attached to the movable object and slidable along the guide rail, and is configured to guide the movable object in a moving direction thereof; and a temperature sensor that is provided in the slider and is configured to detect a temperature of the slider.

[0008] A machine tool according to still another aspect of the present invention includes: a base; a movable object that is provided with a guide member guided by the base and is movable relative to the base; a temperature sensor that is provided in the guide member and is configured to detect a temperature of the guide member; a servo motor that serves as a power source to move the movable object; and a controller that controls the servo motor based on a position command indicating a target movement position of the movable object. The controller corrects the position command based on a temperature of the guide member detected by the temperature sensor.

[0009] According to the present invention, it is possible to provide a machine tool capable of positioning the movable object with higher accuracy to a target movement position.

[0010] Fig. 1 is a perspective view illustrating a machine tool according to a first embodiment of the present invention.Fig. 2 is a perspective view of a guide mechanism and a position detection mechanism in the machine tool illustrated in Fig. 1.Fig. 3 is an exploded view of the guide mechanism and the position detection mechanism illustrated in Fig. 2.Fig. 4 is a cross-sectional view of a slider illustrated in Fig. 2.Fig. 5 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 1.Fig. 6 is a diagram illustrating a coefficient table in Fig. 5.Fig. 7 is a flowchart illustrating a control flow of a servo motor.Fig. 8 is a table illustrating changes in relative displacement in the X axis direction over time in a reciprocating movement of a column in a first verification experiment.Fig. 9 is a table illustrating changes in relative displacement in the Y axis direction over time in a reciprocating movement of the column in a second verification experiment.Fig. 10 is a cross-sectional view illustrating a machine tool according to a second embodiment of the present invention.Fig. 11 is a perspective view illustrating a mounting position of a temperature sensor in a guide mechanism of a machine tool, which is different from the mounting position in Fig. 2, according to a third embodiment of the present invention.Fig. 12 is a side view illustrating a machine tool according to a fourth embodiment of the present invention.Fig. 13 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 12.Fig. 14 is a diagram illustrating a coefficient table in Fig. 13.Fig. 15 is a side view illustrating a machine tool according to a fifth embodiment of the present invention.Fig. 16 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 15.Fig. 17 is a diagram illustrating a coefficient table in Fig. 16.Fig. 18 is a side view illustrating a machine tool according to a sixth embodiment of the present invention.Fig. 19 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 18.Fig. 20 is a diagram illustrating a coefficient table in Fig. 19.

[0011] Embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding members will be denoted by the same reference numerals.

[0012] (First Embodiment) Fig. 1 is a perspective view illustrating a machine tool according to a first embodiment of the present invention. With reference to Fig. 1, a machine tool 100 is a machining center that machines a workpiece by bringing a rotating tool into contact with the workpiece. Machine tool 100 is a horizontal machining center, which means a rotation axis of the rotating tool extends in the horizontal direction. Machine tool 100 is an NC (Numerically Controlled) machine tool which is controlled by a computer according to numerical control to automatically perform various machining operations on a workpiece.

[0013] In the present specification, an axis parallel to the horizontal direction and parallel to a rotation axis of the tool is referred to as a "Z axis", an axis parallel to the horizontal direction and orthogonal to the Z axis is referred to as an "X axis", and an axis parallel to the vertical direction is referred to as a "Y axis". In a front view of a spindle 21 which will be described later, the leftward direction is referred to as a "+X axis direction", and the rightward direction is referred to as a "-X axis direction". In the front view of the spindle 21, the frontward direction is referred to as a "+Z axis direction", and the backward direction is referred to as a "-Z axis direction". The upward direction is referred to as a "+Y axis direction", and the downward direction is referred to as a "-Y axis direction".

[0014] The machine tool to which the present invention is applied is not limited to a horizontal machining center, and may be, for example, a vertical machining center, a lathe that rotates a workpiece and machines the workpiece by bringing a tool into contact with the workpiece, or a composite machine capable of performing a turning operation by using a fixed tool and a milling operation by using a rotating tool. The machine tool to which the present invention is applied may be an AM / SM hybrid machine capable of performing both additive manufacturing (AM) and subtractive manufacturing (SM) on a workpiece.

[0015] Machine tool 100 includes a bed 12, a column 31, a spindle head 22, and a table 41.

[0016] Bed 12 is a base member for supporting column 31, spindle head 22, table 41, and the like, and is fixed to a floor of a factory or the like. Bed 12 is made of metal such as cast iron.

[0017] Column 31 is supported by bed 12. Column 31 as a whole has a portal shape rising upward from bed 12. Column 31 is provided at an end portion of bed 12 in the -Z axis direction. Column 31 can be moved in the X axis direction by various feed mechanisms, guide mechanisms, servo motors, and the like.

[0018] Spindle head 22 is supported by column 31. Spindle head 22 as a whole has a cylindrical shape protruding from column 31 in the +Z axis direction. Spindle head 22 can be moved in the Y axis direction by various feed mechanisms, guide mechanisms, servo motors, and the like.

[0019] Spindle head 22 has a spindle (tool spindle) 21. Spindle 21 can be rotated by a motor about a rotation axis 101 parallel to the Z axis. Spindle 21 has a built-in clamping mechanism for holding a tool which is used to machine a workpiece in machine tool 100. As spindle 21 is rotated, the tool held by spindle 21 is rotated about rotation axis 101.

[0020] Table 41 is supported by bed 12. Table 41 is provided on bed 12. Table 41 is provided at a position away from column 31 in the +Z axis direction. Table 41 is a configured to hold the workpiece. Table 41 holds the workpiece at a position facing spindle 21 in the Z axis direction. Table 41 can be moved in the Z axis direction by various feed mechanisms, guide mechanisms, servo motors, and the like. Table 41 has a built-in turning mechanism for turning a pallet mounted on table 41 about a turning axis that extends in the Y axis direction (the vertical direction).

[0021] With such a configuration, the position of a workpiece to be machined by the tool can be moved in three dimensions by a combination of movements of column 31 in the X axis direction, movements of spindle head 22 (spindle 21) in the Y axis direction, and movements of table 41 in the Z axis direction.

[0022] Each of column 31, spindle head 22 and table 41 corresponds to a movable object 30. column 31 which serves as movable object 30 is movable relative to bed 12 which serves as a base 10. spindle head 22 which serves as movable object 30 is movable relative to column 31 which serves as base 10. Table 41 which serves as movable object 30 is movable relative to bed 12 which serves as base 10.

[0023] Fig. 2 is a perspective view of a guide mechanism and a position detection mechanism in the machine tool illustrated in Fig. 1. Fig. 3 is an exploded view of the guide mechanism and the position detection mechanism in Fig. 2.

[0024] With reference to Figs. 1 to 3, machine tool 100 further includes a linear guide 51 (51A, 51B) and a linear scale 71. Linear guide 51 constitutes the guide mechanism that guides movable object 30 in a moving direction thereof. Linear scale 71 constitutes the position detection mechanism that detects the position of movable object 30.

[0025] Linear guide 51 and linear scale 71 are provided for each movable object 30 of column 31, spindle head 22 (spindle 21), and table 41.

[0026] Linear guide 51 provided for column 31 guides column 31 in the X axis direction. Machine tool 100 includes a linear guide 51A and a linear guide 51B as linear guide 51 that guides column 31 in the X axis direction. Linear guide 51A and linear guide 51B are spaced from each other in the Z axis direction orthogonal to the X axis direction, i.e., the moving direction of column 31. Linear scale 71 provided for column 31 detects the position of column 31 in the X axis direction.

[0027] Linear guide 51 provided for spindle head 22 guides spindle head 22 in the Y axis direction. Machine tool 100 includes a linear guide 51A and a linear guide 51B as linear guide 51 that guides spindle head 22 in the Y axis direction. Linear guide 51A and linear guide 51B are spaced from each other in the X axis direction orthogonal to the Y axis direction, i.e., the moving direction of spindle head 22. Linear scale 71 provided for spindle head 22 detects the position of spindle head 22 in the Y axis direction.

[0028] Linear guide 51 provided for table 41 guides table 41 in the Z axis direction. Machine tool 100 includes a linear guide 51A and a linear guide 51B as linear guide 51 that guides table 41 in the Z axis direction. Linear guide 51A and linear guide 51B are spaced from each other in the X axis direction orthogonal to the Z axis direction, i.e., the moving direction of table 41. Linear scale 71 provided for table 41 detects the position of table 41 in the Z axis direction.

[0029] Linear guide 51 and linear scale 71 provided for each movable object 30 of column 31, spindle head 22, and table 41 have basically the same structure. Hereinafter, as illustrated in Figs. 2 and 3, the structure of linear guide 51 that guides column 31 in the X axis direction and the structure of linear scale 71 that detects the position of column 31 in the X axis direction will be described as an example.

[0030] As illustrated in Figs. 2 and 3, linear guide 51 includes a guide rail 61 and a slider 65 (65J, 65K).

[0031] Guide rail 61 extends in the X axis direction. Guide rail 61 is attached to bed 12. Guide rail 61 is fastened to bed 12 using a bolt or the like. Guide rail 61 is made of metal. In a cross section cut along a Y-Z plane, a central portion of guide rail 61 in the Y axis direction is narrowed in the Z axis direction.

[0032] Slider 65 is attached to column 31. Slider 65 is fastened to column 31 using a bolt or the like. Slider 65 is slidable in the X axis direction along guide rail 61. In a cross section cut along a Y-Z plane, slider 65 is open toward the -Y axis direction and has a concave shape so as to accept guide rail 61 therein.

[0033] Slider 65J and slider 65K are spaced apart from each other in the X axis direction, i.e., the moving direction of column 31.

[0034] Slider 65 includes a main body 66 and a resin member 67 (67p, 67q). Main body 66 is made of metal. Main body 66 is brought into engagement with guide rail 61 via rolling elements (not shown) such as a plurality of balls or rollers. Main body 66 is fastened to column 31. Resin member 67 is made of resin such as polyacetal resin (POM resin). Resin member 67 is adjacent to main body 66 in the X axis direction, i.e., the moving direction of column 31. Resin member 67 is connected to main body 66. The length of resin member 67 in the X axis direction is smaller than the length of main body 66 in the X axis direction.

[0035] Resin member 67p is connected to a side surface of main body 66 facing toward the +X axis direction. Resin member 67q is connected to a side surface of main body 66 facing toward the -X axis direction. Resin member 67q of slider 65J and resin member 67p of slider 65K face each other in the X axis direction.

[0036] Linear scale 71 includes a scale unit 72 and a head unit 76. scale unit 72 is recorded with scale marks (not shown). Scale unit 72 is provided on guide rail 61. Scale unit 72 is not limited to being provided on guide rail 61, and may be provided on bed 12 near guide rail 61. Head unit 76 is movable in the X axis direction integrally with column 31. Head unit 76 can read the scale marks recorded on scale unit 72.

[0037] Scale unit 72 includes a base member 73, a scale body 74, and a cover 75. Base member 73 extends in the X axis direction. Base member 73 is mounted on a top surface of guide rail 61. Scale body 74 is made of an elongated magnetic body which is longer in the X-axis direction, and is recorded with scale marks by magnetism. The scale marks are engraved at equal intervals in the X axis direction. Scale body 74 is supported on base member 73. Cover 75 is attached to base member 73 so as to cover scale body 74. Cover 75 is made of, for example, stainless steel foil.

[0038] Head unit 76 is attached to column 31. Head unit 76 is fastened to column 31 using a bolt or the like. Slider 65J, head unit 76, and slider 65K are spaced apart from each other in the X axis direction. Head unit 76 is provided between slider 65J and slider 65K in the X axis direction. The distance between head unit 76 and slider 65J in the X axis direction may be the same as or different from the distance between head unit 76 and slider 65K in the X axis direction. The head section 76 is provided with a tunnel magnetoresistance (TMR) sensor (not shown) for reading the scale marks recorded on scale unit 72. Head unit 76 is not in contact with linear guide 51. The TMR sensor is provided on a bottom surface of head unit 76, facing scale unit 72 with a gap interposed therebetween in the Y axis direction.

[0039] When column 31 is being moved in the X axis direction, head unit 76 moves in the X axis direction while maintaining a constant distance to slider 65J and slider 65K. The head section 76 moves in the X axis direction while facing scale unit 72 with a constant distance therebetween. The TMR sensor provided in head unit 76 moves in the X axis direction while facing scale body 74 with cover 75 interposed therebetween, and reads the scale marks recorded on scale body 74.

[0040] Fig. 4 is a cross-sectional view of a slider illustrated in Fig. 2. With reference to Figs. 2 to 4, machine tool 100 further includes a temperature sensor 81. Temperature sensor 81 may be a thermistor, for example.

[0041] Temperature sensor 81 is provided in slider 65. Temperature sensor 81 detects a temperature of slider 65. Temperature sensor 81 is provided in slider 65J. Temperature sensor 81 detects a temperature of slider 65J. Temperature sensor 81 is not provided in slider 65K.

[0042] As illustrated in Fig. 4, temperature sensor 81 is supported by resin member 67 so as to be in contact with main body 66. Temperature sensor 81 is supported by resin member 67q of slider 65J. Resin member 67 is provided with a hole 68. Hole 68 penetrates resin member 67 in the X axis direction. Temperature sensor 81 is provided in hole 68. A tip end of temperature sensor 81 in the X axis direction is brought into contact with main body 66. Note that hole 68 is originally provided as a channel for supplying lubrication oil to the rolling elements. In slider 65J where resin member 67q is configured to support temperature sensor 81, the lubrication oil is supplied to the rolling elements through the hole provided in resin member 67p.

[0043] When viewed in the X axis direction, i.e., the slide direction of slider 65, temperature sensor 81 may be configured to detect the temperature of a central portion of slider 65 in the Z axis direction. The tip end of temperature sensor 81 in the X axis direction may contact the center portion of main body 66 in the Z axis direction. Temperature sensor 81 is provided at a position where frictional heat is generated as column 31 is moved in the X axis direction, while the TMR sensor is provided at a position where no frictional heat is generated.

[0044] Linear scale 71 is provided on linear guide 51A. Linear scale 71 is not provided on linear guide 51B. Temperature sensor 81 is provided on slider 65 of linear guide 51A. Temperature sensor 81 is not provided on slider 65 of linear guide 51B.

[0045] Linear scale 71 may be provided on both linear guide 51A and linear guide 51B. Temperature sensor 81 may be provided on both slider 65 of linear guide 51A and slider 65 of linear guide 51B. Temperature sensor 81 may be provided on both slider 65J and slider 65K of each linear guide 51.

[0046] Fig. 5 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 1. With reference to Figs. 1 and 5, machine tool 100 further includes a servo motor 141 (141X, 141Y, 141Z) which serves as a power source to move movable object 30. Servo motor 141X is a power source to move column 31 in the X axis direction, servo motor 141Y is a power source to move spindle head 22 in the Y axis direction, and servo motor 141Z is a power source to move table 41 in the Z axis direction.

[0047] In order to describe the structure of servo motor 141X, as an example, servo motor 141X is mounted on bed 12. A screw of a ball screw which serves as a feed mechanism is connected to an output shaft of servo motor 141, and a nut of the ball screw is connected to column 31. The rotational motion output from servo motor 141X is converted into linear motion in the X axis direction by the ball screw and transmitted to column 31.

[0048] As illustrated in Fig. 5, machine tool 100 further includes a controller 120. Controller 120 controls the operations of machine tool 100.

[0049] Each component of controller 120 is implemented by hardware which includes an arithmetic unit such as a central processing unit (CPU) or various computer processors, a storage device such as a memory or a storage, and a wired or wireless communication line connecting the arithmetic unit and the storage device, and software which is stored in the storage device and is configured to provide processing instructions to the arithmetic unit. The computer program may include a device driver, an operating system, various application programs located in an upper layer of the device driver and the operating system, or a library that provides common functions to these application programs.

[0050] Controller 120 includes a program analysis unit 131, a position command unit 132, a motor control unit 133, and a position command correction unit 161.

[0051] Program analysis unit 131 reads an NC program (processing program) stored in a storage unit 156 which will be described later. Program analysis unit 131 analyzes the NC program. Program analysis unit 131 extracts information related to a target movement position and a movement speed of movable object 30 from the NC program, and outputs the extracted information related to the target movement position and the movement speed to position command unit 132.

[0052] Position command unit 132 sequentially generates an X-axis position command Px, a Y-axis position command Py, and a Z-axis position command Pz according to the movement speed based on the input information related to the target movement position and the movement speed of movable object 30, and outputs the generated position commands Px, Py and Pz to position command correction unit 161 and motor control unit 133.

[0053] Motor control unit 133 controls servo motor 141. Motor control unit 133 generates a control signal (current control signal) according to a position command from position command unit 132, and controls servo motor 141 according to the generated control signal. More specifically, motor control unit 133 generates a control signal according to the position command Px from position command unit 132, and controls servo motor 141X according to the generated control signal. Motor control unit 133 generates a control signal according to the position command Py from position command unit 132, and controls servo motor 141Y according to the generated control signal. Motor control unit 133 generates a control signal according to the position command Pz from position command unit 132, and controls servo motor 141Z according to the generated control signal.

[0054] When a thermal displacement occurs in machine tool 100, position command correction unit 161 corrects the position command Px, Py, Pz from position command unit 132. After the position command Px, Py, Pz is corrected by position command correction unit 161, the corrected position command px, py, pz is input to motor control unit 133. Motor control unit 133 generates a control signal according to the corrected position command, and controls servo motor 141 according to the generated control signal.

[0055] Motor control unit 133 further performs a feedback control on servo motor 141 based on the position data of movable object 30 detected by linear scale 71. More specifically, motor control unit 133 performs a feedback control on servo motor 141X based on the X-axis position data of column 31 detected by linear scale 71. Motor control unit 133 performs a feedback control on servo motor 141Y based on the Y-axis position data of spindle head 22 detected by linear scale 71. Motor control unit 133 performs a feedback control on servo motor 141Z based on the Z-axis position data of table 41 detected by linear scale 71.

[0056] Machine tool 100 includes, a linear guide 51X, a linear guide 51Y, and a linear guide 51Z as linear guide 51.

[0057] Linear guide 51X guides column 31 in the X axis direction, and corresponds to linear guide 51 illustrated in Figs. 2 and 3. Linear guide 51Y guides spindle head 22 in the Y axis direction. Guide rail 61 of linear guide 51Y is mounted on column 31. Slider 65 of linear guide 51Y is mounted on spindle head 22. Linear guide 51Z guides table 41 in the Z axis direction. Guide rail 61 of linear guide 51Z is mounted on bed 12. Slider 65 of linear guide 51Z is mounted on table 41.

[0058] Machine tool 100 includes a temperature sensor 81X, a temperature sensor 81Y, and a temperature sensor 81Z as temperature sensor 81.

[0059] Temperature sensor 81X is provided in slider 65 of linear guide 51X, and corresponds to temperature sensor 81 illustrated in Figs. 2 to 4. Temperature sensor 81X detects a temperature Tx of slider 65 of linear guide 51X (hereinafter, also referred to as "X-axis slider temperature Tx"). Temperature sensor 81Y is provided in slider 65 of linear guide 51Y. Temperature sensor 81Y detects a temperature Ty of slider 65 of linear guide 51Y (hereinafter, also referred to as "Y-axis slider temperature Ty"). Temperature sensor 81Z is provided in slider 65 of linear guide 51Z. Temperature sensor 81Z detects a temperature Tz of slider 65 of linear guide 51Z (hereinafter, also referred to as "Z-axis slider temperature Tz").

[0060] Machine tool 100 further includes a temperature sensor 82. Temperature sensor 82 may be a thermistor, for example. Temperature sensor 82 is provided at a position away from temperature sensor 81 (81X, 81Y, 81Z). Temperature sensor 82 is provided on bed 12. Temperature sensor 82 is provided near a floor of a factory or the like where bed 12 is fixed. Temperature sensor 82 detects a machine body temperature t of machine tool 100. The machine body temperature t is a reference temperature that depends on the ambient temperature (air temperature) of machine tool 100.

[0061] Temperature sensor 81 (81X, 81Y, 81Z) generates a signal indicating the detected temperature (X-axis slider temperature Tx, Y-axis slider temperature Ty, Z-axis slider temperature Tz) of slider 65, and output the signal to controller 120. Temperature sensor 82 generates a signal indicating the detected machine body temperature t of machine tool 100, and outputs the signal to controller 120.

[0062] Controller 120 further includes a temperature data acquisition unit 151. Temperature data acquisition unit 151 acquires temperature data including the temperature of slider 65 (X-axis slider temperature Tx, Y-axis slider temperature Ty, Z-axis slider temperature Tz) detected by temperature sensor 81 and the machine body temperature t of machine tool 100 detected by temperature sensor 82.

[0063] Temperature data acquisition unit 151 determines the X-axis slider temperature Tx based on the signal output from temperature sensor 81X. Temperature data acquisition unit 151 determines the Y-axis slider temperature Ty based on the signal output from temperature sensor 81Y. Temperature data acquisition unit 151 determines the Z-axis slider temperature Tz based on the signal output from temperature sensor 81Z. Temperature data acquisition unit 151 determines the machine body temperature t of machine tool 100 based on the signal output from temperature sensor 82. Temperature data acquisition unit 151 outputs the determined temperature data to position command correction unit 161.

[0064] Fig. 6 is a diagram illustrating a coefficient table in Fig. 5. With reference to Figs. 5 and 6, controller 120 further includes a storage unit 156. Storage unit 156 stores a coefficient table 157.

[0065] Position command correction unit 161 corrects the position command Px, Py, Pz based on the temperature of slider 65 detected by temperature sensor 81.

[0066] More specifically, position command correction unit 161 includes a thermal displacement calculation member 162X, a thermal displacement calculation member 162Y, and a thermal displacement calculation member 162Z. Thermal displacement calculation member 162X calculates a thermal displacement Dx in the X axis direction of machine tool 100. Thermal displacement calculation member 162Y calculates a thermal displacement Dy in the Y axis direction of machine tool 100. Thermal displacement calculation member 162Z calculates a thermal displacement Dz in the Z axis direction of machine tool 100.

[0067] The thermal displacement Dx calculated by thermal displacement calculation member 162X, the thermal displacement Dy calculated by thermal displacement calculation member 162Y, and the thermal displacement Dz calculated by thermal displacement calculation member 162Z are performed by the same method. As an example, the thermal displacement Dx calculated by the thermal displacement calculation member 162X will be described.

[0068] Thermal displacement calculation member 162X reads coefficient table 157 from storage unit 156. Thermal displacement calculation member 162X refers to coefficient table 157 to determine a coefficient Cxx to be applied to the X-axis position correction performed using the X-axis slider temperature Tx. Thermal displacement calculation member 162X calculates a thermal displacement dxx in the X axis direction caused by heat generated by slider 65 of linear guide 51X by substituting the X-axis slider temperature Tx, the machine body temperature t, and the coefficient Cxx into the equation of (Tx - t) × Cxx. The thermal displacement dxx is mainly caused by the heat which is generated by slider 65 of linear guide 51X as column 31 is moved in the X axis direction and is transmitted, via guide rail 61 of linear guide 51X, to bed 12 or to scale unit 72 of linear scale 71 that detects the X-axis position of column 31.

[0069] Thermal displacement calculation member 162X refers to coefficient table 157 to determine a coefficient Cyx to be applied to the X-axis position correction performed using the Y-axis slider temperature Ty. Thermal displacement calculation member 162X calculates a thermal displacement dyx in the X axis direction caused by heat generated by slider 65 of linear guide 51Y by substituting the Y-axis slider temperature Ty, the machine body temperature t, and the coefficient Cyx into the equation of (Ty - t) × Cyx. The thermal displacement dyx is mainly caused by the heat which is generated by slider 65 of linear guide 51Y as spindle head 22 is moved in the Y axis direction and is transmitted, via column 31 and linear guide 51X, to bed 12 or scale unit 72 of linear scale 71 that detects the X-axis position of column 31.

[0070] Thermal displacement calculation member 162X refers to coefficient table 157 to determine a coefficient Czx to be applied to the X-axis position correction performed using the Z-axis slider temperature Tz. Thermal displacement calculation member 162X calculates a thermal displacement dzx in the X axis direction caused by heat generated by slider 65 of linear guide 51Z by substituting the Z-axis slider temperature Tz, the machine body temperature t, and the coefficient Czx into the equation of (Tz - t) × Czx. The thermal displacement dzx is mainly caused by the heat which is generated by slider 65 of linear guide 51Z as table 41 is moved in the Z axis direction and is transmitted, via guide rail 61 of linear guide 51Z, to bed 12 or scale unit 72 of linear scale 71 that detects the X-axis position of column 31.

[0071] Thermal displacement calculation member 162X calculates a thermal displacement Dx which is the sum of the thermal displacement dxx, the thermal displacement dyx, and the thermal displacement dzx (Dx = dxx + dyx + dzx).

[0072] In the same way, thermal displacement calculation member 162Y uses a coefficient Cxy to calculate a thermal displacement dxy in the Y axis direction caused by the heat generated by slider 65 of linear guide 51X, uses a coefficient Cyy to calculate a thermal displacement dyy in the Y axis direction caused by the heat generated by slider 65 of linear guide 51Y, and uses a coefficient Czy to calculate a thermal displacement dzy in the Y axis direction caused by the heat generated by slider 65 of linear guide 51Z. Thermal displacement calculation member 162Y calculates a thermal displacement Dy which is the sum of the thermal displacement dxy, the thermal displacement dyy, and the thermal displacement dzy (Dy = dxy + dyy + dzy).

[0073] Further, thermal displacement calculation member 162Z uses a coefficient Cxz to calculate a thermal displacement dxz in the Z axis direction caused by the heat generated by slider 65 of linear guide 51X, uses a coefficient Cyz to calculate a thermal displacement dyz in the Z axis direction caused by the heat generated by slider 65 of linear guide 51Y, and uses a coefficient Czz to calculate a thermal displacement dzz in the Z axis direction caused by the heat generated by slider 65 of linear guide 51Z. Thermal displacement calculation member 162Z calculates a thermal displacement Dz which is the sum of the thermal displacement dxz, the thermal displacement dyz, and the thermal displacement dzz (Dz = dxz + dyz + dzz).

[0074] The coefficient C illustrated in Fig. 6 is determined in advance through an experiment conducted by the manufacturer of machine tool 100. In the experiment, each movable object 30 (column 31, spindle head 22, table 41) is continuously reciprocated to cause slider 65 that guides movable object 30 in the axial direction to generate heat. Along with the heat generated by slider 65, the temperature of slider 65 and the temperature of the base of machine tool 100 are measured by using a temperature sensor, and the thermal displacement in the X axis direction, the thermal displacement in the Y axis direction, and the thermal displacement in the Z axis direction at each temperature are measured by using a measuring instrument such as a digital gauge. The coefficient C is determined from the relationship between the measured values of temperature and the measured values of thermal displacement.

[0075] As illustrated in Fig. 6, during the X-axis position correction, slider 65 of linear guide 51X corresponds to an axis-direction slider, and each slider 65 of linear guide 51Y and linear guide 51Z corresponds to an orthogonal axis-direction slider. During the Y-axis position correction, slider 65 of linear guide 51Y corresponds to an axis-direction slider, and each slider 65 of linear guide 51X and linear guide 51Z corresponds to an orthogonal axis-direction slider. During the Z-axis position correction, slider 65 of linear guide 51Z corresponds to an axis-direction slider, and each slider 65 of linear guide 51X and linear guide 51Y corresponds to an orthogonal axis-direction slider.

[0076] As illustrated in Figs. 1 and 6, the coefficient C to be applied to the position correction performed using an axis-direction slider temperature has such a value that increases as the distance from the reference position in the axial direction increases, while the coefficient C to be applied to the position correction performed using an orthogonal axis-direction slider temperature has a constant value. In Fig. 6, in machine tool 100 having a machine specification of an X-axis stroke of 800 mm, a Y-axis stroke of 800 mm and a Z-axis stroke of 880 mm, the coefficient C to be applied to position correction performed using an axis-direction slider temperature is simply determined as a predetermined range in each axial direction.

[0077] For example, as the coefficient Cxx to be applied to the X-axis position correction performed using the X-axis slider temperature Tx, Cxx1 is determined in the range of 0 to -200 mm in the X-axis coordinate, Cxx2 larger than Cxx1 is determined in an X-axis coordinate range of -200 to -400 mm, Cxx3 larger than Cxx2 is determined in an X-axis coordinate range of -400 to -600 mm, and Cxx4 larger than Cxx3 is determined in an X-axis coordinate range of -600 to -800 mm. Thermal displacement calculation member 162X determines the coefficient Cxx in the range including the value of the position command Px by comparing the value of the position command Px with coefficient table 157.

[0078] The coefficient C to be applied to the position correction performed using the orthogonal axis-direction slider temperature may be determined as a predetermined range in each axis direction in the same manner as the coefficient C to be applied to the position correction performed using the axis-direction slider temperature.

[0079] Position command correction unit 161 further includes a correction execution member 163. Correction execution member 163 corrects the position command Px based on the thermal displacement Dx calculated by thermal displacement calculation member 162X. Correction execution member 163 corrects the position command Py based on the thermal displacement Dy calculated by thermal displacement calculation member 162Y. Correction execution member 163 corrects the position command Pz based on the thermal displacement Dz calculated by thermal displacement calculation member 162Z.

[0080] More specifically, correction execution member 163 calculates a corrected position command px by subtracting the thermal displacement Dx from the position command Px (px = Px - Dx). Correction execution member 163 calculates a corrected position command py by subtracting the thermal displacement Dy from the position command Py (py = Py - Dy). Correction execution member 163 calculates a corrected position command pz by subtracting the thermal displacement Dz from the position command Pz (pz = Pz - Dz). Correction execution member 163 outputs the calculated corrected position command Px, Py, Pz to servo motor 141 (141X, 141Y, 141Z).

[0081] Fig. 7 is a flowchart illustrating a control flow of the servo motor. With reference to Figs. 5 to 7, as machine tool 100 operates according to the NC program, temperature sensor 81X, temperature sensor 81Y and temperature sensor 81Z detect the X-axis slider temperature Tx, the Y-axis slider temperature Ty and the Z-axis slider temperature Tz, respectively, and temperature sensor 82 detects the machine body temperature t of machine tool 100 in S110.

[0082] Next, in S120, controller 120 (temperature data acquisition unit 151) acquires temperature data including the X-axis slider temperature Tx, the Y-axis slider temperature Ty, the Z-axis slider temperature Tz, and the airframe temperature t, which are detected in the step of S110.

[0083] Next, in S130, controller 120 (thermal displacement calculation member 162X) refers to coefficient table 157 stored in storage unit 156 to determine the coefficient Cxx, the coefficient Cyx and the coefficient Czx. In the same way, controller 120 (thermal displacement calculation member 162Y) refers to coefficient table 157 stored in storage unit 156 to determine the coefficient Cxy, the coefficient Cyy and the coefficient Czy, and controller 120 (thermal displacement calculation member 162Z) refers to coefficient table 157 stored in storage unit 156 to determine the coefficient Cxz, the coefficient Cyz and the coefficient Czz.

[0084] Next, in S140, controller 120 (thermal displacement calculation member 162X) uses the coefficient Cxx determined in the step of S130 and the X-axis slider temperature Tx and the machine body temperature t acquired in the step of S120 to calculate the thermal displacement dxx, uses the coefficient Cyx determined in the step of S130 and the Y-axis slider temperature Ty and the machine body temperature t acquired in the step of S120 to calculate the thermal displacement dyx, and uses the coefficient Cxz determined in the step of S130 and the Z-axis slider temperature Tz and the machine body temperature t acquired in the step of S120 to calculate the thermal displacement dzx.

[0085] In the same way, in S140, controller 120 (thermal displacement calculation member 162Y) calculates the thermal displacement dxy, the thermal displacement dyy and the thermal displacement dzy, and controller 120 (thermal displacement calculation member 162Z) calculates the thermal displacement dxz, the thermal displacement dyz, and the thermal displacement dzz.

[0086] Next, in S150, controller 120 (thermal displacement calculation member 162X) uses the thermal displacement dxx, the thermal displacement dyx and the thermal displacement dzx calculated in step of S140 to calculate the thermal displacement Dx in the X axis direction. In the same way, controller 120 (thermal displacement calculation member 162Y) calculates the thermal displacement Dy in the Y axis direction, and controller 120 (thermal displacement calculation member 162Z) calculates the thermal displacement Dz in the Z axis direction.

[0087] Next, in S160, controller 120 (correction execution member 163) uses the thermal displacement Dx calculated in step of S150 to correct the position command Px from position command unit 132 to the position command px. In the same way, controller 120 (correction execution member 163) uses the thermal displacement Dy calculated in step of S150 to correct the position command Py from position command unit 132 to the position command py, and controller 120 (correction execution member 163) uses the thermal displacement Dz calculated in step of S150 to correct the position command Pz from position command unit 132 to the position command pz.

[0088] Next, in S170, controller 120 (motor control unit 133) controls servo motor 141 (141X, 141Y, 141Z) according to the corrected position command px, py, pz.

[0089] Controller 120 repeats the steps described above each time when a new target position of movable object 30 is designated in the NC program.

[0090] Fig. 8 is a table illustrating changes in relative displacement in the X axis direction over time in a reciprocating movement of the column in the first verification experiment. Fig. 9 is a table illustrating changes in relative displacement in the Y axis direction over time in a reciprocating movement of the column in the second verification experiment.

[0091] With reference to Figs. 1, 8 and 9, machine tool 100 having a machine specification of an X-axis stroke of 800 mm, a Y-axis stroke of 800 mm and a Z-axis stroke of 880 mm was used in both the first verification experiment and the second verification experiment. Column 31 was continuously reciprocated in an X-axis coordinate range of 0 to -200 mm, an X-axis coordinate range of 0 to -400 mm, and an X-axis coordinate range of 0 to -600 mm, respectively (feed rate F = 30000 mm / min, moving time = 8h). The X-axis slider temperature (the temperature of slider 65 of linear guide 51X) at the completion of the reciprocating movement increased by 1.9 °C from the start of the reciprocating movement.

[0092] In the first verification experiment illustrated in Fig. 8, the relative displacement in the X axis direction between the cutting edge of a tool mounted on spindle 21 and table 41 was measured at each position having an X-axis coordinate of -200 mm, an X-axis coordinate of -400 mm and an X-axis coordinate of -600 mm, and the changes in the relative displacement over time were shown in the figure. In the example where the correction is performed, the X-axis position command was corrected using the axis-direction slider temperature (the temperature of slider 65 of linear guide 51X), and in the comparative example where the correction is not performed, the X-axis position command was not corrected.

[0093] In the second verification experiment illustrated in Fig. 9, the relative displacement in the Y axis direction between the cutting edge of the tool mounted on spindle 21 and table 41 was measured at each position with an X-axis coordinate of -200 mm, an X-axis coordinate of -400 mm, and an X-axis coordinate of -600 mm, and the changes in the relative displacement over time was shown in the figure. In the example where the correction is performed, the Y-axis position command was corrected using the orthogonal axis-direction slider temperature (the temperature of slider 65 of linear guide 51X), and in the comparative example where the correction is not performed, the Y-axis position command was not corrected.

[0094] In both the first verification experiment and the second verification experiment, the relative displacement was prevented from occurring between the cutting edge of the tool mounted on spindle 21 and table 41 by correcting the position command.

[0095] To summarize the structure of machine tool 100 according to the first embodiment of the present invention described above, machine tool 100 according to the present embodiment includes: a base 10; a movable object 30 movable relative to base 10; a linear guide 51 that includes a guide rail 61 attached to base 10 and a slider 65 attached to movable object 30 and slidable along guide rail 61, and is configured to guide movable object 30 in a moving direction thereof; and a temperature sensor 81 that is provided in slider 65 and is configured to detect a temperature of slider 65.

[0096] Further, machine tool 100 according to the present embodiment includes: a movable object 30; a linear guide 51 that includes a guide rail 61 attached to base 10 and a slider 65 attached to movable object 30 and slidable along guide rail 61, and is configured to guide movable object 30 in a moving direction thereof; and a temperature sensor 81 that is provided in slider 65 and is configured to detect a temperature of slider 65.

[0097] According to such a configuration, the temperature of slider 65 detected by temperature sensor 81 can be used to determine the thermal displacement caused by the heat generated by slider 65 which is a heat generation source. Thus, it is possible to remove the influence of the thermal displacement caused by the heat generated by slider 65, which makes it possible to position movable object 30 to the target movement position with higher accuracy.

[0098] Machine tool 100 further includes a servo motor 141 that serves as a power source to move movable object 30 and a controller 120 that controls servo motor 141 based on a position command indicating a target movement position of movable object 30. Controller 120 corrects the position command based on a temperature of slider 65 detected by temperature sensor 81.

[0099] According to such a configuration, it is possible to remove the influence of the thermal displacement caused by the heat generated by slider 65 by performing the correction by controller 120. Thus, it is possible to position movable object 30 to the target movement position with higher accuracy.

[0100] Further, controller 120 corrects the position command Px indicating the target movement position of column 31, corrects the position command Py indicating the target movement position of spindle head 22, and corrects the position command Pz indicating the target movement position of table 41, based on the temperature of slider 65 of linear guide 51X detected by temperature sensor 81X, the temperature of slider 65 of linear guide 51Y detected by temperature sensor 81Y, and the temperature of slider 65 of linear guide 51Z detected by temperature sensor 81Z.

[0101] According to such a configuration, not only the influence of the heat generated by the axis-direction slider but also the influence of the heat generated by the orthogonal axis-direction slider can be removed. Thus, it is possible to position movable object 30 to the target movement position with higher accuracy.

[0102] Further, temperature sensor 81 is supported by resin member 67 of slider 65 so as to be in contact with main body 66 of slider 65. According to such a configuration, it is possible to support temperature sensor 81 with a simple configuration and to detect the temperature of slider 65 more accurately using temperature sensor 81.

[0103] Machine tool 100 according to the present embodiment includes: a base 10; a movable object 30 which includes a slider 65 as a guide member guided by base 10 and movable relative to base 10; a temperature sensor 81 which is provided in slider 65 and is configured to detect a temperature of slider 65; a servo motor 141 which serves as a power source to move movable object 30; and a controller 120 which controls servo motor 141 based on a position command indicating a target movement position of movable object 30. Controller 120 corrects the position command based on a temperature of slider 65 detected by temperature sensor 81.

[0104] According to such a configuration, it is possible to remove the influence of the thermal displacement caused by the heat generated by slider 65 by performing the correction by controller 120. Thus, it is possible to position movable object 30 to the target movement position with higher accuracy.

[0105] The machine tool according to the present embodiment includes: a movable object; a linear guide that includes a guide rail and a slider attached to the movable object and slidable along the guide rail, and is configured to guide the movable object in a moving direction thereof; and a temperature sensor that is provided in the slider and is configured to detect a temperature of the slider. The temperature sensor is located in a plane of the slider when viewed in a slide direction of the slider.

[0106] According to such a configuration, the temperature of the slider detected by the temperature sensor can be used to determine the thermal displacement caused by the heat generated by the slider which is a heat generation source. Thus, it is possible to remove the influence of the thermal displacement caused by the heat generated by the slider, which makes it possible to position the movable object to the target movement position with higher accuracy. Further, the temperature sensor is located in the plane of the slider when viewed in the slide direction of the slider. In such a configuration, since the temperature sensor is provided in a space in which the slider moves along with the slide operation thereof, it is possible to easily secure the installation space for the temperature sensor with respect to the slider while avoiding interference between the temperature sensor and the components around the linear guide.

[0107] (Second Embodiment) Fig. 10 is a cross-sectional view illustrating a machine tool according to a second embodiment of the present invention. A machine tool 200 according to the present embodiment has basically the same structure as machine tool 100 according to the first embodiment. Hereinafter, the description of the same components will not be repeated.

[0108] With reference to Fig. 10, in machine tool 200 according to the present embodiment, a slide surface guiding system is employed to guide movable object 30 relative to base 10. As an example, Fig. 10 illustrates a cross-section of a bed 12 which serves as base 10 and a column 31 which serves as movable object 30.

[0109] Bed 12 includes a slide member 16. Column 31 includes a slide member 32. Slide member 16 and slide member 32 face each other in the Y axis direction. Slide member 16 has a slide surface 16a. Slide surface 16a extends in a strip shape which is longer in the X axis direction. Slide member 32 has a slide surface 32a. Slide surface 32a is in surface contact with slide surface 16a via a lubricant. In such a configuration, slide member 32 is guided in the X axis direction by bed 12 (slide member 16).

[0110] A temperature sensor 81 (81X) is provided in slide member 32. Temperature sensor 81 (81X) is embedded in slide member 32. Temperature sensor 81 (81X) is embedded at a position away from slide surface 32a in the Y axis direction. The distance in the Y axis direction between temperature sensor 81 (81X) and slide surface 32a may be 3 mm or less, 5 mm or less, 10 mm or less, or 30 mm or less. Temperature sensor 81 (81X) detects the temperature of slide member 32.

[0111] To summarize the structure of machine tool 200 according to the second embodiment of the present invention described above, machine tool 200 according to the present embodiment includes: a base 10; a movable object 30 that includes a slide member 32 which serves as a guide member guided by base 10 and is movable relative to base 10; a temperature sensor 81 that is provided in slide member 32 and is configured to detect a temperature of slide member 32; a servo motor 141 that serves as a power source to move movable object 30; and a controller 120 that controls servo motor 141 based on a position command indicating a target movement position of movable object 30. Controller 120 corrects the position command based on the temperature of slide member 32 detected by temperature sensor 81.

[0112] According to machine tool 200 with the configuration described above in the second embodiment of the present invention, the same effects as those described in the first embodiment can be achieved.

[0113] (Third Embodiment) Fig. 11 is a perspective view illustrating a mounting position of a temperature sensor in a guide mechanism of a machine tool, which is different from the mounting position in Fig. 2, according to a third embodiment of the present invention. With reference to Fig. 11, the mounting position of temperature sensor 81 may be any position at which the temperature of slider 65 can be detected.

[0114] Temperature sensor 81 may be mounted on main body 66. Temperature sensor 81 may be mounted on a side surface of main body 66 facing the X axis direction or may be mounted on a side surface of main body 66 facing the Z axis direction. According to such a configuration, even when the distance between slider 65J and slider 65K is small, it is possible to secure a mounting space for temperature sensor 81.

[0115] (Fourth Embodiment) The machine tool according to the present embodiment has basically the same structure as machine tool 100 according to the first embodiment. Hereinafter, the description of the same components will not be repeated.

[0116] Fig. 12 is a side view illustrating a machine tool according to a fourth embodiment of the present invention. Fig. 13 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 12. Fig. 14 is a diagram illustrating a coefficient table in Fig. 13.

[0117] With reference to Figs. 12 to 14, the machine tool according to the present embodiment includes a temperature sensor 81X and a temperature sensor 81Z as temperature sensors 81. Temperature sensor 81X is provided in slider 65 of linear guide 51X, and is configured to detect an X-axis slider temperature Tx. Temperature sensor 81Z is provided in slider 65 of linear guide 51Z, and is configured to detect a Z-axis slider temperature Tz.

[0118] Slider 65 has a mounting surface 211. An object to be guided by slider 65 is mounted on mounting surface 211. In slider 65 of linear guide 51X, column 31 is mounted on mounting surface 211. Mounting surface 211 is orthogonal to the Y axis direction. In slider 65 of linear guide 51Z, table 41 is mounted on mounting surface 211. Mounting surface 211 is orthogonal to the Y axis direction.

[0119] In the present embodiment, the X-axis slider temperature Tx and the Z-axis slider temperature Tz are used as the orthogonal axis-direction slider temperature to correct the position command indicating the target movement position of spindle head 22 movable in the Y axis direction (i.e., to perform the Y-axis position correction).

[0120] As illustrated in Figs. 13 and 14, a coefficient table 201 is stored in storage unit 156. Position command correction unit 161 includes a thermal displacement calculation member 162Y. Thermal displacement calculation member 162Y calculates a thermal displacement dxy and a thermal displacement dzy in the Y axis direction, which will be described hereinafter.

[0121] Thermal displacement calculation member 162Y reads coefficient table 201 from storage unit 156. Thermal displacement calculation member 162Y refers to coefficient table 201 to determine a coefficient Sxy to be applied to the Y-axis position correction performed using the X-axis slider temperature Tx and a coefficient Szy to be applied to the Y-axis position correction performed using the Z-axis slider temperature Tz.

[0122] Thermal displacement calculation member 162Y calculates a thermal displacement dxy in the Y axis direction caused by heat generated by slider 65 of linear guide 51X by substituting the X-axis slider temperature Tx, the machine body temperature t, and the coefficient Sxy into the equation of (Tx - t) × Sxy. The thermal displacement dxy is mainly caused by the heat which is generated by slider 65 of linear guide 51X as column 31 is moved in the X axis direction and is transmitted to column 31 via mounting surface 211 of slider 65 of linear guide 51X to cause column 31 to undergo thermal expansion in the Y axis direction orthogonal to mounting surface 211 of slider 65 of linear guide 51X.

[0123] Thermal displacement calculation member 162Y calculates a thermal displacement dzy in the Y axis direction caused by heat generated by slider 65 of linear guide 51Z by substituting the Z-axis slider temperature Tz, the machine body temperature t, and the coefficient Szy into the equation of (Tz - t) × Szy. The thermal displacement dzy is mainly caused by the heat which is generated by slider 65 of linear guide 51Z as table 41 is moved in the Z axis direction and is transmitted to table 41 via mounting surface 211 of slider 65 of linear guide 51Z to cause table 41 to undergo thermal expansion in the Y axis direction orthogonal to mounting surface 211 of slider 65 of linear guide 51Z.

[0124] The coefficient S illustrated in Fig. 14 is determined in advance by an experiment conducted by the manufacturer of the machine tool.

[0125] In the experiment, column 31 is continuously reciprocated in the X axis direction to cause slider 65 of linear guide 51X that guides column 31 to generate heat. Along with the heat generated by slider 65, the temperature of slider 65 of linear guide 51X and the temperature of the base of machine tool 100 are measured using a temperature sensor, and the thermal displacement in the Y axis direction of column 31 at each temperature is measured using a measuring instrument such as a digital gauge. The coefficient Sxy is determined from the relationship between the measured values of temperature and the measured values of thermal displacement. Further, table 41 is continuously reciprocated in the Z axis direction to cause slider 65 of linear guide 51Z that guides table 41 to generate heat. Along with the heat generated by slider 65, the temperature of slider 65 of linear guide 51Z and the temperature of the base of machine tool 100 are measured using a temperature sensor, and the thermal displacement in the Y axis direction of table 41 at each temperature is measured by using a measuring instrument such as a digital gauge. The coefficient Szy is determined from the relationship between the measured values of temperature and the measured values of thermal displacement.

[0126] Correction execution member 163 calculates a corrected position command py based on the thermal displacement dxy and the thermal displacement dzy (py = Py - dxy + dzy).

[0127] As indicated by an arrow 310 in Fig. 12, column 31 thermally expands in the +Y axis direction due to the heat from slider 65 of linear guide 51X, and the contact point of tool T in workpiece W is displaced in the +Y axis direction. In this case, the correction direction of the position command Py of spindle head 22 based on the thermal displacement dxy should be in the -Y axis direction. As indicated by an arrow 320 in Fig. 12, table 41 is thermally expanded in the +Y axis direction due to the heat from slider 65 of linear guide 51Z, and the contact point of tool T in workpiece W is displaced in the -Y axis direction. In this case, the correction direction of the position command Py of spindle head 22 based on the thermal displacement dzy should be in the +Y axis direction.

[0128] Correction execution member 163 outputs the calculated corrected position command py to servo motor 141Y.

[0129] To summarize the structure of the machine tool according to the fourth embodiment of the present invention described above, the machine tool according to the present embodiment includes: a movable object; a linear guide 51 (51X / 51Z) that includes a guide rail 61 and a slider 65 attached to the movable object and slidable along guide rail 61, and is configured to guide the movable object in a moving direction thereof; and a temperature sensor 81 (81X / 81Z) that is provided in slider 65 and is configured to detect a temperature of slider 65.

[0130] The movable object includes a first movable object (column 31 / table 41) movable in a first direction (X axis direction / Z axis direction). Slider 65 has a mounting surface 211 on which the first movable object (column 31 / table 41) is mounted, and linear guide 51 (51X / 51Z) is configured to guide the first movable object (column 31 / table 41) in the first direction (X axis direction / Z axis direction). The movable object further includes a second movable object (spindle head 22) movable in a second direction (Y axis direction) orthogonal to both mounting surface 211 and the first direction (X axis direction / Z axis direction). The machine tool further includes a servo motor 141Y that serves as a power source to move the second movable object (spindle head 22), and a controller 120 that controls servo motor 141Y based on a position command indicating a target movement position of the second movable object (spindle head 22). Controller 120 corrects the position command indicating the target movement position of the second movable object (spindle head 22) based on a temperature of slider 65 detected by the temperature sensor 81X / 81Z.

[0131] Further, the machine tool according to the present embodiment includes: a first movable object (column 31 / table 41) movable in a first direction (X axis direction / Z axis direction); a linear guide 51X / 51Z that includes slider 65 which has a mounting surface 211 on which the first movable object (column 31 / table 41) is mounted, and is configured to guide the first movable object (column 31 / table 41) in the first direction (X axis direction / Z axis direction); a temperature sensor 81X / 81Z that is provided in slider 65 and is configured to detect a temperature of slider 65; a second movable object (spindle head 22) movable in a second direction (Y axis direction) orthogonal to both mounting surface 211 and the first direction (X axis direction / Z axis direction); a servo motor 141Y that serves as a power source to move the second movable object (spindle head 22); and a controller 120 that controls servo motor 141Y based on a position command indicating a target movement position of the second movable object (spindle head 22). Controller 120 corrects the position command indicating the target movement position of the second movable object (spindle head 22) based on a temperature of slider 65 detected by temperature sensor 81X / 81Z.

[0132] According to such a configuration, even if the first movable object (column 31 / table 41) thermally expands in the second direction (Y axis direction) due to the heat generated by slider 65 that guides the first movable object (column 31 / table 41), it is possible to position the second movable object (spindle head 22) to the target movement position with higher accuracy by correcting the position command indicating the target movement position of the second movable object (main shaft head 22) movable in the second direction (Y axis direction) based on the temperature of slider 65.

[0133] (Fifth Embodiment) The machine tool according to the present embodiment has basically the same structure as machine tool 100 according to the first embodiment. Hereinafter, the description of the same components will not be repeated.

[0134] Fig. 15 is a side view illustrating a machine tool according to a fifth embodiment of the present invention. Fig. 16 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 15. Fig. 17 is a diagram illustrating a coefficient table in Fig. 16.

[0135] With reference to Figs. 15 to 17, the machine tool according to the present embodiment includes a temperature sensor 81Y as temperature sensor 81. Temperature sensor 81Y is provided in slider 65 of linear guide 51Y, and is configured to detect the Y-axis slider temperature Ty. In slider 65 of linear guide 51Y, spindle head 22 is mounted on mounting surface 211. Mounting surface 211 is orthogonal to the Z axis direction.

[0136] In the present embodiment, the Y-axis slider temperature Ty is used as the orthogonal axis-direction slider temperature to correct the position command indicating the target movement position of table 41 movable in the Z axis direction (i.e., to perform the Z-axis position correction).

[0137] As illustrated in Figs. 16 and 17, a coefficient table 202 is stored in storage unit 156. Position command correction unit 161 includes a thermal displacement calculation member 162Z. Thermal displacement calculation member 162Z calculates a thermal displacement dyz in the Z axis direction, which will be described hereinafter.

[0138] Thermal displacement calculation member 162Z reads coefficient table 202 from storage unit 156. Thermal displacement calculation member 162Z refers to coefficient table 202 to determine a coefficient Syz to be applied to the Z-axis position correction performed using the Y-axis slider temperature Ty.

[0139] Thermal displacement calculation member 162Z calculates a thermal displacement dyz in the Z axis direction caused by heat generated by slider 65 of linear guide 51Y by substituting the Y-axis slider temperature Ty, the machine body temperature t, and the coefficient Syz into the equation of (Ty - t) × Syz. The thermal displacement dyz is mainly caused by the heat which is generated by slider 65 of linear guide 51Y as spindle head 22 is moved in the Y axis direction and is transmitted to spindle head 22 via mounting surface 211 of slider 65 of linear guide 51Y to cause spindle head 22 to undergo thermal expansion in the Z axis direction orthogonal to mounting surface 211 of slider 65 of linear guide 51Y.

[0140] The coefficient S illustrated in Fig. 17 is determined in advance by an experiment performed by the manufacturer of the machine tool.

[0141] In the experiment, spindle head 22 is continuously reciprocated in the Y axis direction to cause slider 65 of linear guide 51Y that guides spindle head 22 to generate heat. Along with the heat generated by slider 65, the temperature of slider 65 of linear guide 51Y and the temperature of the base of machine tool 100 are measured using a temperature sensor, and the thermal displacement in the Z axis direction of spindle head 22 at each temperature is measured using a measuring instrument such as a digital gauge. The coefficient Syz is determined from the relationship between the measured values of temperature and the measured values of thermal displacement.

[0142] Correction execution member 163 calculates a corrected position command pz based on the thermal displacement dyz (pz = Pz + dyz).

[0143] As indicated by an arrow 330 in Fig. 15, spindle head 22 thermally expands in the +Z axis direction due to the heat from slider 65 of linear guide 51Y, which causes a contact point of tool T in workpiece W to displace in the +Z axis direction. In this case, the correction direction of the position command Pz of table 41 based on the thermal displacement dyz should be in the +Z axis direction.

[0144] Correction execution member 163 outputs the corrected position command pz to servo motor 141Z.

[0145] To summarize the structure of the machine tool according to the fifth embodiment of the present invention described above, the machine tool according to the present embodiment includes: a movable object; a linear guide 51 (51Y) that includes a guide rail 61 and a slider 65 attached to the movable object and slidable along guide rail 61, and is configured to guide the movable object in a moving direction thereof; and a temperature sensor 81 (81Y) that is provided in slider 65 and is configured to detect a temperature of slider 65.

[0146] The movable object includes a first movable object (spindle head 22) movable in a first direction (Y axis direction). Slider 65 has a mounting surface 211 on which the first movable object (spindle head 22) is mounted, and linear guide 51 (51Y) is configured to guide the first movable object (spindle head 22) in the first direction (Y axis direction). The movable object further includes a second movable object (table 41) movable in a second direction (Z axis direction) orthogonal to both mounting surface 211 and the first direction (Y axis direction). The machine tool further includes a servo motor 141Z that serves as a power source to move the second movable object (table 41), and a controller 120 that controls servo motor 141Z based on a position command indicating a target movement position of the second movable object (table 41). Controller 120 corrects the position command indicating the target movement position of the second movable object (table 41) based on the temperature of slider 65 detected by temperature sensor 81Y.

[0147] Further, the machine tool according to the present embodiment includes: a first movable object (spindle head 22) movable in a first direction (Y axis direction); a linear guide 51Y that includes slider 65 which has a mounting surface 211 on which the first movable object (spindle head 22) is mounted, and is configured to guide the first movable object (spindle head 22) in the first direction (Y axis direction); a temperature sensor 81Y that is provided in slider 65 and is configured to detect a temperature of slider 65; a second movable object (table 41) movable in a second direction (Z axis direction) orthogonal to both mounting surface 211 and the first direction (Y axis direction); a servo motor 141Z that serves as a power source to move the second movable object (table 41); and a controller 120 that controls servo motor 141Z based on a position command indicating a target movement position of the second movable object (table 41). Controller 120 corrects the position command indicating the target movement position of the second movable object (table 41) based on a temperature of slider 65 detected by temperature sensor 81Y.

[0148] According to such a configuration, even if the first movable object (spindle head 22) thermally expands in the second direction (Z axis direction) due to the heat generated by slider 65 that guides the first movable object (spindle head 22), it is possible to position the second movable object (table 41) to the target movement position with higher accuracy by correcting the position command indicating the target movement position of the second movable object (table 41) movable in the second direction (Z axis direction) based on the temperature of slider 65.

[0149] (Sixth Embodiment) The machine tool according to a sixth embodiment combines the machine tool according to the fourth embodiment and the machine tool according to the fifth embodiment. Hereinafter, the description of the same components will not be repeated.

[0150] Fig. 18 is a side view illustrating a machine tool according to the sixth embodiment of the present invention. Fig. 19 is a diagram illustrating a functional configuration of a control system of the machine tool illustrated in Fig. 18. Fig. 20 is a diagram illustrating a coefficient table in Fig. 19.

[0151] With reference to Figs. 18 to 20, the machine tool according to the present embodiment includes a temperature sensor 81X, a temperature sensor 81Y, and a temperature sensor 81Z as temperature sensor 81. As illustrated in Figs. 19 and 20, a storage unit 256 stores a coefficient table 203. Coefficient table 203 includes a coefficient Sxy to be applied to the Y-axis position correction performed using the X-axis slider temperature Tx, a coefficient Szy to be applied to the Y-axis position correction performed using the Z-axis slider temperature Tz, and a coefficient Syz to be applied to the Z-axis position correction performed using the Y-axis slider temperature Ty.

[0152] In the present embodiment, the X-axis slider temperature Tx and the Z-axis slider temperature Tz are used as the orthogonal axis-direction slider temperature to correct the position command indicating the target movement position of spindle head 22 movable in the Y axis direction (i.e., to perform the Y-axis position correction), which is the same as that in the fourth embodiment. Further, the Y-axis slider temperature Ty is used as the orthogonal axis-direction slider temperature to correct the position command indicating the target movement position of table 41 movable in the Z axis direction (i.e., to perform the Z-axis position correction), which is the same as that in the fifth embodiment.

[0153] According to such a configuration, it is possible to achieve the same effects as those described in the fourth embodiment and the fifth embodiment.

[0154] The machine tool according to the present invention may be configured by arbitrarily combining the machine tools described in the first to sixth embodiments.

[0155] It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in all respects. The scope of the present invention is defined by the terms of the claims rather than the description of the embodiments above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0156] This application is based on Japanese Patent Application No. 2024-077845 filed on May 13, 2024, and No. 2025-019345 filed on February 7, 2025, with the Japan Patent Office, the entire contents of which are hereby incorporated by reference.

[0157] 10: base; 12: bed; 16, 32: slide member; 16a, 32a: slide surface; 21: spindle; 22: spindle head; 30: movable object; 31: column; 41: table; 51, 51A, 51B, 51X, 51Y, 51Z: linear guide; 61: guide rail; 65, 65J, 65K: slider; 66: main body; 67, 67p, 67q: resin member; 68: hole; 71: linear scale; 72: scale unit; 73: base member; 74: scale body; 75: cover; 76: head unit; 81, 81X, 81Y, 81Z, 82: temperature sensor; 100, 200: machine tool; 101: rotation axis; 120: controller; 131: program analysis unit; 132: position command unit; 133: motor control unit; 141, 141X, 141Y, 141Z: servo motor; 151: temperature data acquisition unit; 156: storage unit; 157, 201, 202, 203: coefficient table; 161: position command correction unit; 162X, 162Y, 162Z: thermal displacement calculation member; 163: correction execution member; 211: mounting surface.

Claims

1. A machine tool comprising: a movable object; a linear guide that includes a guide rail and a slider attached to the movable object and slidable along the guide rail, and is configured to guide the movable object in a moving direction thereof; and a temperature sensor that is provided in the slider and is configured to detect a temperature of the slider.

2. The machine tool according to claim 1, wherein the temperature sensor is located in a plane of the slider when viewed in a slide direction of the slider.

3. The machine tool according to claim 1, wherein the movable object includes a first movable object movable in a first direction, the slider has a mounting surface on which the first movable object is mounted, and the linear guide is configured to guide the first movable object in the first direction, the movable object further includes a second movable object movable in a second direction orthogonal to both the mounting surface and the first direction, the machine tool further includes: a servo motor that serves as a power source to move the second movable object; and a controller that controls the servo motor based on a position command indicating a target movement position of the second movable object, wherein the controller corrects the position command indicating the target movement position of the second movable object based on a temperature of the slider detected by the temperature sensor.

4. The machine tool according to claim 3, wherein the first movable object is a column or table movable in the horizontal direction, and the second movable object is a spindle head movable in the vertical direction.

5. The machine tool according to claim 3, wherein the first movable object is a spindle head movable in the vertical direction, and the second movable object is a table movable in the horizontal direction.

6. The machine tool according to claim 1 or 2, further comprising: a servo motor that serves as a power source to move the movable object; and a controller that controls the servo motor based on a position command indicating a target movement position of the movable object, wherein the controller corrects the position command based on a temperature of the slider detected by the temperature sensor, the movable object includes a first movable object movable in a first direction, a second movable object movable in a second direction orthogonal to the first direction, and a third movable object movable in a third direction orthogonal to both the first direction and the second direction, the linear guide includes a first linear guide that guides the first movable object in the first direction, a second linear guide that guides the second movable object in the second direction, and a third linear guide that guides the third movable object in the third direction, the temperature sensor includes a first temperature sensor that detects a temperature of the slider of the first linear guide, a second temperature sensor that detects a temperature of the slider of the second linear guide, and a third temperature sensor that detects a temperature of the slider of the third linear guide, and the controller corrects the position command indicating the target movement position of the first movable object based on the temperature of the slider of the first linear guide detected by the first temperature sensor, the temperature of the slider of the second linear guide detected by the second temperature sensor, and the temperature of the slider of the third linear guide detected by the third temperature sensor.

7. The machine tool according to claim 1 or 2, wherein the slider includes a main body which is made of metal and is brought into engagement with the guide rail via a rolling element, and a resin member which is made of resin, provided adjacent to the main body in the moving direction of the movable object and connected to the main body, and the temperature sensor is supported by the resin member so as to be in contact with the main body.

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