JP2010029973A - Grinding machine and grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding machine and a grinding method that always move a grinder in the axial direction of a work when a command to move in the Z-axis direction is given. <P>SOLUTION: The grinding machine includes: first displacement monitoring means 71, 61 and 62 for always monitoring the relative displacement L1 of a headstock 20 in the X-axis direction of an absolute coordinate system with a bed 10 as a reference; second displacement monitoring means 72, 61 and 62 for always monitoring the relative displacement L2 of a tailstock 30 in the X-axis direction of the absolute coordinate system with the bed 10 as a reference; an inclination calculation means 63 for calculating the inclination θ1 of the work axis with respect to a predetermined reference Z-axis based on the relative displacement L1 of the headstock 20 and the relative displacement L2 of the tailstock 30; and a correction means 64 for correcting the taper error of the work W based on the inclination θ1 of the work axis. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a grinding machine and a grinding method.

  When grinding a long workpiece, the long workpiece is generally sandwiched between a spindle stock and a tailstock. When a workpiece is clamped between the headstock and the tailstock, if the rotation axis of the headstock and the rotation axis of the tailstock do not match, the workpiece rotates with respect to the Z-axis direction of the grinding machine. The axis tilts. And the longer the target workpiece is, the farther the headstock and tailstock are located. For example, due to thermal displacement, the rotation axis of the headstock and the rotation axis of the tailstock will not match. There is. If the workpiece is to be ground into a cylindrical shape in this state, it becomes tapered.

In order to solve this problem, for example, there is one described in JP-A-6-114702 (Patent Document 1). In Patent Document 1, a touch sensor provided on a grindstone table is brought into contact with a measurement unit provided on a headstock and a measurement unit of a tailstock, and the inclination of both is calculated. Then, according to the calculated inclination, the tailstock is moved in the X direction so that the rotation axis of the headstock and the rotation axis of the tailstock coincide.
JP-A-6-114702

  However, since the inclination between the rotation axis of the headstock and the rotation axis of the tailstock is measured using a touch sensor provided on the grindstone platform, the inclination cannot be measured during actual grinding. Since the amount of thermal displacement of the headstock and tailstock may change even during grinding, the conventional technology tilts the rotation axis of the headstock and the rotation axis of the tailstock even after correction. May occur. That is, there is a possibility that the displacement amount at the time of measurement and the displacement amount at the time of grinding are different. Then, high precision grinding cannot be performed. Therefore, it is desired that the grindstone always move in the direction of the central axis of the workpiece when a command to move in the Z-axis direction is issued. However, even if the touch sensor provided on the grindstone is used, it cannot be solved because measurement by the touch sensor cannot be performed during grinding.

  Furthermore, in the grinding machine disclosed in Patent Document 1, an operation of bringing the touch sensor into contact with the measurement unit must be performed for thermal displacement correction, in addition to the normal grinding operation. Therefore, there is a problem that the cycle time becomes long.

  The present invention has been made in view of such circumstances, and when a command to move in the Z-axis direction is issued without increasing the cycle time, the grindstone always moves in the direction of the center axis of the workpiece. It is an object of the present invention to provide a grinding machine and a grinding method that enable the above.

  Hereinafter, each means suitable for solving the above-described problems will be described with additional effects and the like as necessary.

<First grinding machine>
(Means 1) The grinding machine of means 1 is
Bed and
A headstock and a tailstock mounted on the bed and supporting both ends of the workpiece;
A whetstone base placed on the bed and movable relative to the headstock and the tailstock in the X-axis direction and the Z-axis direction;
First displacement monitoring means for constantly monitoring relative displacement of the headstock in the absolute coordinate system X-axis direction with respect to the bed;
Second displacement monitoring means for constantly monitoring relative displacement in the absolute coordinate system X-axis direction of the tailstock with respect to the bed;
An inclination calculating means for calculating an inclination of a workpiece axis with respect to a preset reference Z axis based on the relative displacement of the headstock and the relative displacement of the tailstock;
Correction means for correcting a taper error of the workpiece based on the inclination of the workpiece axis;
It is characterized by providing.

  According to the means 1, the relative displacement in the absolute coordinate system X-axis direction of the headstock and the tailstock is always monitored by the first displacement monitoring means and the second displacement monitoring means. Here, since the reference bed is fixed, the relative displacement can be constantly monitored by using this bed as a reference. Therefore, the inclination calculation means can always calculate the inclination of the workpiece axis with respect to the reference Z axis. That is, even during grinding, the inclination calculating means can calculate the inclination. Then, the taper error of the workpiece is corrected by the correcting means based on the inclination of the workpiece axis. That is, even if the workpiece axis is inclined with respect to the reference Z axis due to thermal displacement or the like, the grindstone can always move in the direction of the center axis of the workpiece when a command to move in the Z axis direction is issued. As a result, highly accurate processing is possible.

  Furthermore, according to the present invention, only the normal grinding operation can be performed without performing an operation different from the conventional normal grinding operation (operation of bringing the touch sensor for thermal displacement correction into contact with the measurement unit). The above processing becomes possible. Therefore, according to this invention, it can prevent that cycle time becomes long compared with the past.

(Means 2) In the grinding machine of means 1,
The grinding wheel platform is movable relative to the bed in the Z-axis direction,
A third displacement monitoring means for constantly monitoring the relative displacement of the grindstone table in the absolute coordinate system X-axis direction with respect to the bed;
The inclination calculating means calculates an inclination in the Z-axis direction in which the wheel head moves relative to the reference Z-axis based on a relative displacement of the wheel head,
The correction means corrects the taper error of the workpiece based on the inclination of the workpiece axis and the inclination of the grinding wheel base in the Z-axis direction.

  According to the means 2, the relative displacement in the absolute coordinate system X-axis direction of the grindstone table is constantly monitored by the third displacement monitoring means with reference to the bed. Here, as a cause of the taper error of the workpiece, in addition to the workpiece axis being inclined with respect to the reference Z axis, there is an inclination of the grinding wheel base in the Z axis movement direction. That is, according to the means 2, since the taper error of the workpiece is corrected in consideration of both, the grinding can be performed with higher accuracy.

  (Means 3) In the grinding machine of means 1 or 2, the inclination of the workpiece axis is a direction between supporting points connecting the supporting point of the workpiece by the headstock and the supporting point of the workpiece by the tailstock, It is an inclination with respect to the reference Z axis. The direction between the support points becomes the rotation axis of the workpiece. According to the means 3, the taper error of the workpiece can be reliably corrected.

(Means 4) In the grinding machine of means 2,
The wheel head moves relative to the Z-axis direction along a wheel head guide provided on the bed,
The inclination in the Z-axis direction of the wheel head is the inclination of the guide for the wheel head with respect to the reference Z axis.
According to the means 4, the inclination of the grinding wheel base in the Z-axis direction can be reliably calculated. As a result, grinding can be performed with higher accuracy.

(Means 5) In any of the grinding machines of means 1 to 4,
The first displacement monitoring means or the second displacement monitoring means,
A temperature sensor for detecting the temperature of the headstock or the tailstock,
Relationship storage means for storing in advance a first relationship or a second relationship between the temperature of the headstock or the tailstock and the amount of thermal displacement in the X-axis direction of the absolute coordinate system;
Displacement estimation for estimating the relative displacement of the headstock or the tailstock based on the temperature detected by the temperature sensor and the first relationship or the second relationship stored in the relationship storage means Means,
Is provided.
According to the means 5, the amount of displacement of the spindle stock or tailstock is estimated by monitoring the temperature of the spindle stock or tailstock. Thereby, the influence by the thermal displacement of a headstock and a tailstock can be correct | amended reliably.

(Means 6) In the grinding machine of means 2,
The third displacement monitoring means includes
A temperature sensor for detecting a temperature in the vicinity of the grinding wheel platform or the grinding wheel platform;
Relationship storage means for storing in advance a third relationship between the temperature of the grinding wheel platform or the vicinity of the grinding wheel platform and the amount of thermal displacement in the absolute coordinate system X-axis direction;
Displacement estimation means for estimating the relative displacement of the grindstone table based on the temperature detected by the temperature sensor and the third relation stored in the relation storage means;
Is provided.

  According to the means 6, the displacement amount of the grinding wheel base is estimated by monitoring the temperature of the grinding wheel base or the vicinity of the grinding wheel base (for example, the guide rail for the grinding wheel base). Thereby, the influence by the thermal displacement of a grindstone base can be correct | amended reliably.

(Means 7) In the grinding machine according to any one of the means 1 to 4, the first displacement monitoring means and the second displacement monitoring means are displacement sensors.
According to the means 7, the displacement of the headstock and the tailstock is directly monitored. Thereby, the influence of all the displacements including the thermal displacement of the headstock and the tailstock can be reliably corrected.

(Means 8) In the grinding machine of means 7, the first displacement monitoring means monitors the relative displacement of the headstock at the support point of the workpiece with respect to the bed.
According to the means 8, since the relative displacement of the support point of the work in the headstock is directly monitored, the work inclination can be calculated more reliably.

(Means 9) In the grinding machine of means 7, the first displacement monitoring means monitors the relative displacement of the reference seat provided on the headstock with respect to the bed.
According to the means 9, the displacement of the reference seat of the headstock is monitored, not the displacement of the support point of the work in the headstock. Depending on the position, it may not be possible to directly monitor the displacement of the work support point in the headstock. In such a case, the displacement of the headstock can be reliably monitored by monitoring the displacement of the reference seat. Can do.

(Means 10) In the grinding machine of the means 7, the second displacement monitoring means monitors the relative displacement of the tailstock with respect to the bed at a support point of the workpiece.
According to the means 10, since the relative displacement of the support point of the work in the tailstock is directly monitored, the work inclination can be calculated more reliably.

(Means 11) In the grinding machine of means 7, the second displacement monitoring means monitors the relative displacement of the reference seat provided on the tailstock with respect to the bed.
According to the means 11, the displacement of the reference seat of the tailstock is monitored, not the displacement of the support point of the work in the tailstock. Depending on the position, it may not be possible to directly monitor the displacement of the work support point of the tailstock. In such a case, the displacement of the tailstock is reliably monitored by monitoring the displacement of the reference seat. can do.

(Means 12) In the grinding machine of means 2 or 4, the third displacement monitoring means is a displacement sensor.
According to the means 12, the displacement of the wheel head is directly monitored. Thereby, the influence of all the displacements including the thermal displacement of the grindstone can be reliably corrected.

<Second grinding machine>
(Means 13) The grinding machine of means 13 is
Bed and
A headstock and a tailstock mounted on the bed and supporting both ends of the workpiece;
A whetstone base placed on the bed and movable relative to the headstock and the tailstock in the X-axis direction and the Z-axis direction and relative to the bed in the Z-axis direction;
Third displacement monitoring means for constantly monitoring relative displacement in the absolute coordinate system X-axis direction of the grindstone table with respect to the bed;
An inclination calculating means for calculating an inclination in the Z-axis direction in which the grindstone table moves with respect to a preset reference Z-axis based on the relative displacement of the grindstone table;
Correction means for correcting a taper error of the workpiece based on the inclination in the Z-axis direction of the grindstone table;
It is characterized by providing.

  According to the means 13, the relative displacement in the absolute coordinate system X-axis direction of the grindstone table is constantly monitored by the third displacement monitoring means with reference to the bed. Here, since the reference bed is fixed, the relative displacement can be constantly monitored by using this bed as a reference. Therefore, the inclination calculating means can always calculate the inclination in the Z-axis direction in which the grindstone base moves with respect to the reference Z-axis. That is, even during grinding, the inclination calculating means can calculate the inclination. Then, the taper error of the workpiece is corrected by the correcting means based on the inclination in the Z-axis direction along which the grindstone table moves. In other words, even if the Z-axis direction in which the wheel head moves due to thermal displacement is tilted with respect to the reference Z-axis, the wheel always moves in the direction of the center axis of the workpiece when a command to move in the Z-axis direction is issued. can do. As a result, highly accurate processing is possible.

(Means 14) In the grinding machine of means 13,
The third displacement monitoring means includes
A temperature sensor for detecting a temperature in the vicinity of the grinding wheel platform or the grinding wheel platform;
Relationship storage means for storing in advance a third relationship between the temperature of the grinding wheel platform or the vicinity of the grinding wheel platform and the amount of thermal displacement in the absolute coordinate system X-axis direction;
Displacement estimation means for estimating the relative displacement of the grindstone table based on the temperature detected by the temperature sensor and the third relation stored in the relation storage means;
Is provided.

  According to the means 14, the amount of displacement of the grinding wheel base is estimated by monitoring the temperature of the grinding wheel base or the vicinity of the grinding wheel base (for example, the guide rail for the grinding wheel base). Thereby, the influence by the thermal displacement of a grindstone base can be correct | amended reliably.

(Means 15) In the grinding machine of means 13, the third displacement monitoring means is a displacement sensor.
According to the means 15, the displacement of the wheel head is directly monitored. Thereby, the influence of all the displacements including the thermal displacement of the grindstone can be reliably corrected.

<First grinding method>
(Means 16) The grinding method of means 16 is as follows:
Grinding is performed by relatively moving the grindstone table placed on the bed in the X-axis direction and the Z-axis direction with respect to the work supported at both ends by the headstock and the tailstock placed on the bed. A grinding method to perform,
Constantly monitoring the relative displacement of the headstock in the X-axis direction of the absolute coordinate system with respect to the bed,
Constantly monitoring the relative displacement of the tailstock in the absolute coordinate system X-axis direction with respect to the bed,
Based on the relative displacement of the headstock and the relative displacement of the tailstock, the inclination of the workpiece axis with respect to a preset reference Z-axis is calculated,
The taper error of the workpiece is corrected based on the inclination of the workpiece axis.
According to the means 16, the same effects as those obtained by the grinding machine according to the means 1 can be obtained.

<Second grinding method>
(Means 17) The grinding method of the means 17 is as follows.
Grinding is performed by relatively moving the grindstone table placed on the bed in the X-axis direction and the Z-axis direction with respect to the work supported at both ends by the headstock and the tailstock placed on the bed. A grinding method to perform,
The relative displacement in the absolute coordinate system X-axis direction of the grindstone table is constantly monitored with respect to the bed,
Based on the relative displacement of the grinding wheel platform, the inclination of the Z axis direction in which the grinding wheel platform moves with respect to a preset reference Z axis is calculated,
The taper error of the workpiece is corrected based on the Z-axis direction inclination of the grindstone table.
According to the means 17, the same effect as that obtained by the grinding machine according to the means 13 is obtained.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a grinding machine and a grinding method according to the present invention will be described with reference to the drawings. The first embodiment is a grinding machine having a grindstone traverse configuration, and uses a temperature sensor. The second embodiment is a grinding machine having a table traverse configuration and uses a temperature sensor. The third embodiment is a grinding machine having a grindstone traverse configuration, and uses a displacement sensor. The fourth embodiment is a grinding machine having a table traverse configuration and uses a displacement sensor.

<First embodiment>
The grinding machine 1 of 1st embodiment is demonstrated with reference to FIG. 1 and FIG. FIG. 1 is a plan view of the grinding machine 1. FIG. 2 is a control block diagram of the grinding machine 1.

  As shown in FIG. 1, the grinding machine 1 has a so-called grinding wheel traverse configuration. The grinding machine 1 includes a bed 10, a headstock 20, a tailstock 30, a grindstone support device 40, a control device 60, and temperature sensors 71 to 74.

  The bed 10 has a substantially rectangular shape and is disposed on the floor. On the upper surface of the bed 10, grinding wheel table guide rails 11 and 12 on which a grinding wheel table traverse base 41 constituting the grinding wheel support device 40 can slide extend in the absolute coordinate system Z-axis direction (left and right direction in FIG. 1). And are formed parallel to each other. However, the wheel head guide rails 11 and 12 may be inclined from the Z-axis direction of the absolute coordinate system due to thermal displacement or the like. The bed 10 is provided with a Z-axis ball screw (not shown) for the grindstone table for driving the grindstone traverse base 41 in the left-right direction in FIG. 1 between the guide rails 11 and 12 for the grindstone table. A grinding wheel base Z-axis motor 17 for rotating the grinding wheel base Z-axis ball screw is disposed.

  The head stock 20 includes a head stock main body 21, a main shaft 22, and a main shaft center 23. The headstock body 21 is fixed on the bed 10. A main shaft 22 is inserted and supported in the main body 21 so as to be rotatable about the main shaft. The rotation axis of the spindle 22 is set so as to coincide with the absolute coordinate system Z-axis, but may be inclined with respect to the absolute coordinate system Z-axis due to the influence of thermal displacement of the spindle stock 20 or the like. Furthermore, a spindle center 23 that supports one axial end of the workpiece W is attached to the right end of the spindle 22.

  The tailstock 30 includes a tailstock body 31 and a tailstock center 32. The tailstock body 31 is fixed on the bed 10 so as to face the headstock 20. The tailstock main body 31 is formed with a hole penetrating in the left-right direction in FIG. A tailstock center 32 is rotatably inserted and supported in the through hole of the tailstock main body 31. The tailstock center 32 supports the other end of the workpiece W in the axial direction. That is, the tailstock center 32 is disposed so as to face the spindle center 23. The rotation axis of the tailstock center 32 is located coaxially with the main axis of the main axis 22, that is, so as to coincide with the absolute coordinate system Z-axis. The rotation axis of the tailstock center 32 is set to coincide with the absolute coordinate system Z-axis, but may be inclined with respect to the absolute coordinate system Z-axis due to the influence of thermal displacement of the tailstock 30 and the like.

  The spindle center 23 and the tailstock center 32 support both ends of the workpiece W. In other words, the workpiece W is supported by the spindle center 23 and the tailstock center 32 so as to be rotatable around the rotation axis of the spindle 22. Therefore, the direction between the support points connecting the support point of the workpiece W by the spindle center 23 and the support point of the workpiece W by the tailstock center 32 becomes the rotation axis of the workpiece W. The rotation axis of the workpiece W basically coincides with the absolute coordinate system Z-axis. However, the rotation axis of the workpiece W may be inclined with respect to the absolute coordinate system Z-axis due to the influence of the thermal displacement of the headstock 20 and the tailstock 30.

  The grinding wheel support device 40 includes a grinding wheel base traverse base 41, a grinding wheel base 42, a grinding wheel 43, and a grinding wheel rotation motor 44. The grinding wheel base traverse base 41 is formed in a substantially rectangular flat plate shape, and is slidably disposed on the grinding wheel head guide rails 11 and 12 on the upper surface of the bed 10. The grinding wheel base traverse base 41 is connected to the nut member of the grinding wheel head ball screw, and moves along the grinding wheel head guide rails 11 and 12 by driving the grinding wheel head Z-axis motor 17. That is, when the grinding wheel base guide rails 11 and 12 coincide with the absolute coordinate system Z-axis, the grinding wheel base traverse base 41 can move in the absolute coordinate system Z-axis direction. When 11 and 12 are inclined with respect to the absolute coordinate system Z-axis, the grindstone traverse base 41 moves in a direction inclined with respect to the absolute coordinate system Z-axis.

  On the upper surface of this traverse base 41, X-axis guide rails 41a and 41b on which the grindstone base 42 can slide are formed so as to extend in the vertical direction (X-axis direction) in FIG. Has been. Further, an X-axis ball screw (not shown) for driving the grinding wheel base 42 in the vertical direction in FIG. 1 is disposed between the X-axis guide rails 41a and 41b on the grinding wheel base traverse base 41. An X-axis motor 41c that rotates the X-axis ball screw is disposed.

  The grinding wheel base 42 is slidably disposed on the X-axis guide rails 41 a and 41 b in the upper surface of the grinding wheel base traverse base 41. And the grindstone base 42 is connected to the nut member of the X-axis ball screw, and moves along the X-axis guide rails 41a and 41b by the drive of the X-axis motor 41c. That is, the grindstone base 42 can move relative to the bed 10, the spindle stock 20, and the tailstock 30 in the X-axis direction and the Z-axis direction.

  A hole penetrating in the left-right direction in FIG. 1 is formed in the lower portion of FIG. A grinding wheel rotating shaft member is supported in the through hole of the grinding wheel base 42 so as to be rotatable around the central axis of the grinding wheel (around the Z axis). A grinding wheel 43 is coaxially attached to one end (left end in FIG. 1) of the grinding wheel rotating shaft member. A grinding wheel rotating motor 44 is fixed on the upper surface of the grinding wheel base 42. A pulley is suspended between the other end of the grinding wheel rotating shaft member (the right end in FIG. 1) and the rotating shaft of the grinding wheel rotating motor 44, so that the grinding wheel 43 is driven by the driving of the grinding wheel rotating motor 44. Rotate around.

  The control device 60 performs NC control of the rotation of the main shaft 22 and the X-axis position and the Z-axis position of the grindstone table 42. That is, the outer peripheral surface of the workpiece W is ground by controlling the X-axis position and the Z-axis position of the grinding wheel 43 with respect to the workpiece W while the grinding wheel 43 is rotated by the control device 60. As will be described later, the control device 60 corrects the moving direction of the grindstone table 42 based on the outputs of the temperature sensors 71 to 74.

  The temperature sensor 71 is provided near the built-in motor (not shown) for rotating the spindle stock 20, in particular, the spindle 22, and detects the temperature of the part. The temperature sensor 72 is provided in the tailstock 30 and detects the temperature of the tailstock 30. The temperature sensor 73 is provided in the vicinity of one end of the grindstone guide rail 11 and detects the temperature of the part. The temperature sensor 74 is provided in the vicinity of the other end of the grindstone guide rail 11 and detects the temperature of the part.

  Next, processing related to Z-axis correction by the control device 60 will be described with reference to FIG. As shown in FIG. 2, the functional block of the control device 60 includes a relationship storage unit 61, a displacement estimation unit 62, an inclination calculation unit 63, and a correction unit 64.

  Here, as described above, the workpiece axis may be inclined with respect to the absolute coordinate system Z-axis due to the influence of the thermal displacement of the headstock 20 and the tailstock 30. In such a case, when a command for moving the grinding wheel base 42 in the Z-axis direction is issued, the direction in which the grinding wheel base 42 moves does not coincide with the rotation axis of the workpiece W. Then, when it is desired to grind the cylindrical outer peripheral surface, it is ground in a tapered shape. Further, the grindstone guide rails 11 and 12 may be inclined with respect to the absolute coordinate system Z due to the influence of thermal displacement. Even in such a case, when a command to move the grindstone table 42 in the Z-axis direction is issued, the direction in which the grindstone table 42 moves does not coincide with the rotation axis of the workpiece W. Also in this case, the workpiece is ground in a tapered shape as described above. Accordingly, by correcting the taper error as described below, it is possible to reliably grind the cylindrical outer peripheral surface without being affected by thermal displacement or the like when it is desired to grind the cylindrical outer peripheral surface.

  The relationship storage unit 61 stores the following first relationship, second relationship, and third relationship. The first relationship is a relationship between the temperature of the headstock 20 and the amount of thermal displacement in the absolute coordinate system X-axis direction of the headstock 20. The second relationship is a relationship between the temperature of the tailstock 30 and the amount of thermal displacement of the tailstock 30 in the absolute coordinate system X-axis direction. The third relationship is the relationship between the temperature of one end of the wheel head guide rail 11 and the amount of thermal displacement in the absolute coordinate system X-axis direction at the one end portion, and the temperature of the other end of the wheel head guide rail 11. This is the relationship with the amount of thermal displacement in the absolute coordinate system X-axis direction at the other end portion.

  Based on the temperature of the headstock 20 detected by the temperature sensor 71 and the first relationship, the displacement estimation unit 62 calculates a displacement L1 in the absolute coordinate system X-axis direction at the support point of the workpiece W by the spindle center 23. . Further, the displacement estimation unit 62 displaces the support point of the work W by the tailstock center 32 in the absolute coordinate system X-axis direction based on the temperature of the tailstock 30 detected by the temperature sensor 72 and the second relationship. L2 is calculated.

  At the same time, the displacement estimation unit 62 calculates the displacement L3 in the absolute coordinate system X-axis direction at the one end portion based on the temperature of the one end of the grindstone guide rail 11 detected by the temperature sensor 73 and the third relationship. calculate. Further, the displacement estimation unit 62 is based on the temperature at the other end of the grinding wheel guide rail 11 detected by the temperature sensor 74 and the third relationship, and the displacement in the absolute coordinate system X-axis direction at the other end portion. L4 is calculated.

  Here, the displacement L1 corresponds to the relative displacement of the headstock 20 in the absolute coordinate system X-axis direction when the bed 10 is used as a reference. That is, the first displacement that constantly monitors the relative displacement in the X-axis direction of the headstock 20 with the bed 10 as a reference by the temperature sensor 71, the first relationship of the relationship storage unit 61, and the displacement estimation unit 62. Configure monitoring means. The displacement L2 corresponds to the relative displacement of the tailstock 30 in the absolute coordinate system X-axis direction when the bed 10 is used as a reference. That is, the temperature sensor 72, the second relationship of the relationship storage unit 61, and the displacement estimation unit 62 constantly monitor the relative displacement in the absolute coordinate system X-axis direction of the tailstock 30 with the bed 10 as a reference. Displacement monitoring means is configured.

  The displacements L3 and L4 are relative displacements in the absolute coordinate system X-axis direction of the wheel head guide rail 11 when the bed 10 is used as a reference, that is, in the absolute coordinate system X-axis direction of the wheel head 42 using the bed 10 as a reference. Is equivalent to the relative displacement. That is, the temperature sensor 73, 74, the third relationship of the relationship storage unit 61, and the displacement estimation unit 62 constantly monitor the relative displacement in the absolute coordinate system X-axis direction of the grindstone table 42 with the bed 10 as a reference. The three displacement monitoring means is configured.

  The inclination calculation unit 63 calculates the inclination θ1 of the rotation axis of the workpiece W with respect to the reference Z axis based on the displacements L1 and L2. Further, the inclination calculating unit 63 calculates the inclination θ2 of the grindstone table guide rail 11 with respect to the reference Z axis based on the displacements L3 and L4. Here, the reference Z axis coincides with the absolute coordinate system Z axis.

  The correction unit 64 corrects the taper error of the workpiece W based on the inclination θ1 of the rotation axis of the workpiece W with respect to the reference Z axis and the inclination θ2 of the grindstone guide rail 11 with respect to the reference Z axis.

  As described above, the first displacement monitoring means and the second displacement monitoring means constantly monitor the relative displacements L1 and L2 of the headstock 20 and the tailstock 30 in the absolute coordinate system X-axis direction with the bed 10 as a reference. Yes. Here, since the reference bed 10 is fixed, the relative displacements L1 and L2 can be constantly monitored by using the bed 10 as a reference. Therefore, the inclination calculating unit 63 can always calculate the inclination θ1 of the rotation axis of the workpiece W with respect to the reference Z axis. That is, even during grinding, the inclination calculating unit 63 can calculate the inclination θ1.

  Further, the third displacement monitoring means constantly monitors relative displacements L3 and L4 in the absolute coordinate system X-axis direction of the grindstone table 42 with the bed 10 as a reference. The inclination calculation unit 63 can always calculate the inclination θ2 of the grindstone guide rail 11 with respect to the reference Z axis. That is, even during grinding, the inclination calculating unit 63 can calculate the inclination θ2.

  Here, as a cause of the taper error of the workpiece W, in addition to the rotation axis of the workpiece W being inclined with respect to the reference Z axis, there is an inclination of the grinding wheel base 42 in the Z axis movement direction. Then, the correction unit 64 corrects the taper error of the workpiece W based on the inclination θ1 of the rotation axis of the workpiece W and the inclination θ2 of the guide rail 11 for the grindstone table. That is, even if the rotation axis of the workpiece W is inclined with respect to the reference Z axis due to thermal displacement or the like, further, even if the grindstone guide rail 11 is inclined with respect to the reference Z axis, When an instruction to move is issued, the grinding wheel 43 can always move in the direction of the central axis of the workpiece W. As a result, highly accurate processing is possible.

  Furthermore, according to the present embodiment, only a normal grinding operation is performed without performing an operation different from a normal grinding operation as in the past (an operation in which a touch sensor for thermal displacement correction is brought into contact with the measurement unit). Thus, the above processing can be performed. Therefore, according to this embodiment, it can prevent that cycle time becomes long compared with the past.

<Second embodiment>
The grinding machine 100 of 2nd embodiment is demonstrated with reference to FIG. FIG. 3 is a plan view of the grinding machine 100.

  As shown in FIG. 3, the grinding machine 100 has a so-called table traverse configuration. The grinding machine 100 includes a bed 110, a headstock 120, a tailstock 130, a grinding wheel base 140, a table 150, a control device 160, and temperature sensors 171 to 174.

  The bed 110 has a convex shape, that is, a front side (lower side in FIG. 3) is wide and a back side (upper side in FIG. 3) is narrow, and is arranged on the floor. On the upper surface of the bed 110, table guide rails 111 and 112 on which the table 150 can slide are formed so as to extend in the absolute coordinate system Z-axis direction (left and right direction in FIG. 3) and in parallel with each other. Yes. However, the table guide rails 111 and 112 may be inclined from the absolute coordinate system Z-axis direction due to thermal displacement or the like. Further, on the bed 110, wheel head guide rails 113 and 114 on which the wheel head 140 can slide are formed so as to extend in the absolute coordinate system X-axis (vertical direction in FIG. 3) and in parallel with each other. ing. Further, a Z-axis ball screw for table (not shown) for driving the table 150 in the left-right direction in FIG. 3 is arranged between the table guide rails 111 and 112 on the bed 110. A table Z-axis motor 115 for rotating the Z-axis ball screw is disposed. The bed 110 is provided with a grindstone table X-axis ball screw (not shown) for driving the grindstone table 140 in the vertical direction of FIG. 3 between the grindstone guide rails 113 and 114. A grinding wheel table X-axis motor 116 for rotating the table X-axis ball screw is disposed.

  The table 150 is formed in a horizontally long rectangular flat plate shape, and is slidably disposed on the table guide rails 111 and 112 on the upper surface of the bed 110. The table 150 is connected to a nut member of a table ball screw, and moves along the table guide rails 111 and 112 by driving the table Z-axis motor 115. That is, when the table guide rails 111 and 112 coincide with the absolute coordinate system Z-axis, the table 150 can move in the absolute coordinate system Z-axis direction, but the table guide rails 111 and 112 are absolute. When tilted with respect to the coordinate system Z axis, the table 150 moves in a direction tilted from the absolute coordinate system Z axis.

  The head stock 120 includes a head stock main body 21, a main shaft 22, and a main shaft center 23. The headstock main body 21 is fixed to one end side (left side in FIG. 3) on the table 150. A main shaft 22 is inserted into and supported by the headstock main body 21 so as to be rotatable around the main shaft. The rotation axis of the spindle 22 is set so as to coincide with the absolute coordinate system Z-axis, but may be inclined with respect to the absolute coordinate system Z-axis due to the influence of thermal displacement of the spindle stock 20 or the like. Furthermore, a spindle center 23 that supports one axial end of the workpiece W is attached to the right end of the spindle 22.

  The tailstock 130 includes a tailstock body 31 and a tailstock center 32. The tailstock body 31 is fixed to the other end side (the right side in FIG. 3) on the table 150 so as to face the headstock 120. The tailstock body 31 has a hole penetrating in the left-right direction in FIG. A tailstock center 32 is rotatably inserted and supported in the through hole of the tailstock main body 31. The tailstock center 32 supports the other end of the workpiece W in the axial direction. That is, the tailstock center 32 is disposed so as to face the spindle center 23. The rotation axis of the tailstock center 32 is located coaxially with the main axis of the main axis 22, that is, so as to coincide with the absolute coordinate system Z-axis. The rotation axis of the tailstock center 32 is set to coincide with the absolute coordinate system Z-axis, but may be tilted with respect to the absolute coordinate system Z-axis due to the influence of thermal displacement of the tailstock 130 and the like.

  The spindle center 23 and the tailstock center 32 support both ends of the workpiece W. In other words, the workpiece W is supported by the spindle center 23 and the tailstock center 32 so as to be rotatable around the rotation axis of the spindle 22. Therefore, the direction between the support points connecting the support point of the workpiece W by the spindle center 23 and the support point of the workpiece W by the tailstock center 32 becomes the rotation axis of the workpiece W. The rotation axis of the workpiece W basically coincides with the absolute coordinate system Z-axis. However, the rotational axis of the workpiece W may be tilted with respect to the absolute coordinate system Z-axis due to the thermal displacement of the headstock 120 and the tailstock 130 and the thermal displacement of the table guide rails 111 and 112.

  The grinding wheel platform 140 is slidably disposed on the grinding wheel platform guide rails 113 and 114 on the upper surface of the bed 110. The grinding wheel platform 140 is connected to a nut member of the grinding wheel platform X-axis ball screw, and moves along the grinding wheel platform X-axis guide rails 113 and 114 by driving the grinding wheel platform X-axis motor 116. That is, the grindstone platform 140 can move relative to the bed 110, the table 150, the headstock 120, and the tailstock 130 in the X-axis direction.

  And the hole penetrated in the left-right direction of FIG. 3 is formed in the lower part of FIG. A grinding wheel rotating shaft member is supported in the through hole of the grinding wheel base 140 so as to be rotatable around the central axis of the grinding wheel (around the Z axis). A grinding wheel 142 is coaxially attached to one end (left end in FIG. 3) of the grinding wheel rotating shaft member. A grinding wheel rotating motor 141 is fixed to the upper surface of the grinding wheel base 140. A pulley is suspended between the other end of the grinding wheel rotating shaft member (the right end in FIG. 3) and the rotating shaft of the grinding wheel rotating motor 141, so that the grinding wheel 142 is driven by the grinding wheel rotating motor 141. Rotate around.

  The control device 160 performs NC control on the rotation of the spindle 22, the Z-axis position of the table 150, and the X-axis position of the grindstone table 140. That is, the outer peripheral surface of the workpiece W is ground by controlling the X-axis position and the Z-axis position of the grinding wheel 142 with respect to the workpiece W while the grinding wheel 142 is rotated by the control device 160. As will be described later, the control device 160 corrects the moving direction of the grindstone table 140 to the X axis based on the outputs of the temperature sensors 171 to 174.

  The temperature sensor 171 is provided near a built-in motor (not shown) for rotating the headstock 120, in particular, the main shaft 22, and detects the temperature of the part. The temperature sensor 172 is provided on the tailstock 130 and detects the temperature of the tailstock 130. The temperature sensor 173 is provided near one end of the table guide rail 111 and detects the temperature of the part. The temperature sensor 174 is provided near the other end of the table guide rail 111 and detects the temperature of the part.

  Next, processing related to correction by the control device 160 will be described with reference to FIG. The relationship storage unit 61 stores the following first relationship, second relationship, and third relationship. The first relationship is a relationship between the temperature of the headstock 120 and the amount of thermal displacement in the absolute coordinate system X-axis direction of the headstock 120. The second relationship is a relationship between the temperature of the tailstock 130 and the amount of thermal displacement of the tailstock 130 in the absolute coordinate system X-axis direction. The third relationship is the relationship between the temperature of one end of the table guide rail 111 and the amount of thermal displacement in the absolute coordinate system X-axis direction at the one end portion, the temperature of the other end of the table guide rail 111, and the other It is a relationship with the amount of thermal displacement in the absolute coordinate system X-axis direction at the end portion.

  The displacement estimation unit 62 is based on the temperature of the headstock 120 detected by the temperature sensor 171 and the first relationship, and the absolute coordinate system at the support point of the workpiece W by the spindle center 23 when the table 150 is used as a reference. A displacement L11 in the X-axis direction is calculated. Further, the displacement estimation unit 62 supports the work W by the tailstock center 32 when the table 150 is used as a reference based on the temperature of the tailstock 130 detected by the temperature sensor 172 and the second relationship. The displacement L12 in the absolute coordinate system X-axis direction at is calculated.

  At the same time, the displacement estimation unit 62 uses the temperature of one end of the table guide rail 111 detected by the temperature sensor 173 and the third relationship, and the absolute coordinates at the one end portion when the bed 110 is used as a reference. A displacement L13 in the system X-axis direction is calculated. Further, the displacement estimation unit 62 is based on the temperature at the other end of the table guide rail 111 detected by the temperature sensor 174 and the third relationship, and the displacement is estimated at the other end portion when the bed 110 is used as a reference. A displacement L14 in the absolute coordinate system X-axis direction is calculated.

  Here, considering the displacements L11, L13, and L14, when the bed 110 is used as a reference, the relative displacement of the headstock 120 in the absolute coordinate system X-axis direction can be derived. That is, the relative displacement in the absolute coordinate system X-axis direction of the headstock 120 with the bed 110 as a reference by the temperature sensors 171, 173, 174, the first and third relationships of the relationship storage unit 61, and the displacement estimation unit 62. First displacement monitoring means for constantly monitoring the above is configured. Further, in consideration of the displacements L12, L13, and L14, when the bed 110 is used as a reference, the relative displacement of the tailstock 130 in the absolute coordinate system X-axis direction can be derived. That is, the relative displacement in the absolute coordinate system X-axis direction of the tailstock 130 with respect to the bed 110 is determined by the temperature sensors 172 to 174, the second and third relationships of the relationship storage unit 61, and the displacement estimation unit 62. Second displacement monitoring means for constantly monitoring is configured.

  The inclination calculation unit 63 calculates the inclination θ11 of the rotation axis of the workpiece W when the table 150 is used as a reference, based on the displacements L11 and L12. Further, the inclination calculating unit 63 calculates the inclination θ12 of the table guide rail 111 with respect to the reference Z axis based on the displacements L13 and L14. Here, the reference Z axis coincides with the absolute coordinate system Z axis. That is, the inclination (θ11 + θ12) is the inclination of the rotation axis of the workpiece W with respect to the reference Z axis. Then, the correction unit 64 corrects the taper error of the workpiece W based on the inclination of the rotation axis of the workpiece W with respect to the reference Z axis.

  As described above, also in the second embodiment, as in the first embodiment, the inclination calculating unit 63 can always calculate the inclination of the rotation axis of the workpiece W with respect to the reference Z axis. Therefore, even if the rotation axis of the workpiece W is inclined with respect to the reference Z axis due to thermal displacement or the like, the grinding wheel 142 always moves in the direction of the center axis of the workpiece W when a command to move in the Z axis direction is issued. can do. As a result, highly accurate processing is possible.

<Third embodiment>
A grinding machine 200 according to a third embodiment will be described with reference to FIG. FIG. 4 is a plan view of the grinding machine 200. The grinding machine 200 of the third embodiment adopts the same configuration as the grinding machine 1 of the first embodiment. Hereinafter, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

  The grinding machine 200 of 3rd embodiment has changed the temperature sensors 71-74 which comprise the grinding machine 1 of 1st embodiment into the displacement sensors 271-274. The displacement sensor 271 detects a displacement L21 in the absolute coordinate system X-axis direction with respect to the bed 10 at the support point of the work W in the headstock 20, that is, the spindle center 23. The displacement sensor 272 detects the displacement L22 in the absolute coordinate system X-axis direction with respect to the bed 10 at the support point of the work W in the tailstock 30, that is, the tailstock center 32. The displacement sensor 273 is provided in the vicinity of one end of the grindstone guide rail 11 and detects a displacement L23 in the absolute coordinate system X-axis direction with respect to the bed 10 of the part. The displacement sensor 274 is provided in the vicinity of the other end of the grindstone guide rail 11 and detects a displacement L24 in the absolute coordinate system X-axis direction with respect to the bed 10 of the part.

  Next, processing related to Z-axis correction by the control device 260 will be described with reference to FIG. As shown in FIG. 5, the functional block of the control device 260 includes an inclination calculation unit 261 and a correction unit 262.

  The inclination calculation unit 261 calculates the inclination θ1 of the rotation axis of the workpiece W with respect to the reference Z axis based on the displacements L21 and L22. Furthermore, the inclination calculation unit 261 calculates the inclination θ2 of the grindstone table guide rail 11 with respect to the reference Z axis based on the displacements L23 and L24. Here, the reference Z axis coincides with the absolute coordinate system Z axis. The correction unit 262 corrects the taper error of the workpiece W based on the inclination θ1 of the rotation axis of the workpiece W with respect to the reference Z axis and the inclination θ2 of the grindstone guide rail 11 with respect to the reference Z axis.

  As described above, since the displacements L21 to L24 are directly monitored by the displacement sensors 271 to 274, the inclination θ1 of the workpiece W and the inclination θ2 of the grindstone guide rail 11 can be calculated more reliably.

<Modification of Third Embodiment>
The said deformation | transformation aspect is demonstrated with reference to FIG. FIG. 6 is a plan view including the vicinity of the headstock 20 and the tailstock 30. In the third embodiment, the displacement sensors 271 and 272 directly detect the displacement of the spindle center 23 and the tailstock center 32. However, depending on the position of each component, the displacement sensors 271 and 272 may not be provided. In such a case, as shown in FIG. 6, the displacement sensor 271 detects the displacement of the reference seat 21 a attached to the headstock body 21, and the displacement sensor 272 is attached to the tailstock body 31. The detected displacement of the reference seat 31a is detected. This is substantially the same as the third embodiment. The displacement sensors 273 and 274 provided on the grindstone guide rail 11 may also be provided with a separate reference seat to detect the displacement of the reference seat.

<Fourth embodiment>
A grinding machine 300 according to a fourth embodiment will be described with reference to FIG. FIG. 7 is a plan view of the grinding machine 300. The grinding machine 300 of the fourth embodiment adopts the same configuration as the grinding machine 100 of the second embodiment. Hereinafter, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

  The grinding machine 300 of 4th embodiment has changed the temperature sensors 171-174 which comprise the grinding machine 100 of 2nd embodiment into the displacement sensors 371-374. The displacement sensor 371 is disposed on the table 150 and detects a displacement L31 in the absolute coordinate system X-axis direction with respect to the table 150 at the support point of the work W in the headstock 120, that is, the spindle center 23. The displacement sensor 272 is disposed on the table 150 and detects a displacement L32 in the absolute coordinate system X-axis direction with respect to the table 150 at the support point of the work W in the tailstock 130, that is, the tailstock center 32. The displacement sensor 373 is provided in the vicinity of one end of the table guide rail 111 and detects a displacement L23 in the absolute coordinate system X-axis direction with respect to the bed 110 of the part. The displacement sensor 374 is provided in the vicinity of the other end of the table guide rail 111, and detects a displacement L24 in the absolute coordinate system X-axis direction with respect to the bed 110 of the part.

  Next, processing relating to Z-axis correction by the control device 360 will be described with reference to FIG. 5 used in the third embodiment. As shown in FIG. 5, the functional block of the control device 360 includes an inclination calculation unit 261 and a correction unit 262.

  The inclination calculation unit 261 calculates the inclination θ11 of the rotation axis of the workpiece W based on the table 150 based on the displacements L31 and L32. Further, the inclination calculating unit 261 calculates the inclination θ12 of the table guide rail 111 with respect to the reference Z axis based on the displacements L33 and L34. Here, the reference Z axis coincides with the absolute coordinate system Z axis. That is, the inclination (θ11 + θ12) is the inclination of the rotation axis of the workpiece W with respect to the reference Z axis. Then, the correction unit 362 corrects the taper error of the workpiece W based on the inclination of the rotation axis of the workpiece W with respect to the reference Z axis.

  As described above, since the displacement sensors 371 to 374 directly monitor the displacements L31 to L34, the inclination θ1 of the workpiece W can be calculated more reliably.

1 is a plan view of a grinding machine 1. FIG. 2 is a control block diagram of the grinding machine 1. FIG. 1 is a plan view of a grinding machine 100. FIG. 2 is a plan view of a grinding machine 200. FIG. 3 is a control block diagram of the grinding machine 200. FIG. It is a top view including the headstock 20 and the tailstock 30 vicinity. 2 is a plan view of a grinding machine 300. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100,200,300: Grinding machine 10,110: Bed, 20,120: Headstock, 30,130: Tailstock 40: Grinding wheel support device, 42, 140: Grinding wheel table 60, 160, 260, 360: Control devices 71 to 74: Temperature sensor 150: Table

Claims (17)

Bed and
A headstock and a tailstock mounted on the bed and supporting both ends of the workpiece;
A whetstone base placed on the bed and movable relative to the headstock and the tailstock in the X-axis direction and the Z-axis direction;
First displacement monitoring means for constantly monitoring relative displacement of the headstock in the absolute coordinate system X-axis direction with respect to the bed;
Second displacement monitoring means for constantly monitoring relative displacement in the absolute coordinate system X-axis direction of the tailstock with respect to the bed;
An inclination calculating means for calculating an inclination of a work axis with respect to a preset reference Z axis based on the relative displacement of the headstock and the relative displacement of the tailstock;
Correction means for correcting a taper error of the workpiece based on the inclination of the workpiece axis;
A grinding machine comprising: The grinding wheel platform is movable relative to the bed in the Z-axis direction,
A third displacement monitoring means for constantly monitoring the relative displacement of the grindstone table in the absolute coordinate system X-axis direction with respect to the bed;
The inclination calculating means calculates an inclination in the Z-axis direction in which the wheel head moves relative to the reference Z-axis based on a relative displacement of the wheel head,
The grinding machine according to claim 1, wherein the correction unit corrects a taper error of the workpiece based on an inclination of the workpiece axis and an inclination of the grindstone table in the Z-axis direction.   The inclination of the workpiece axis is an inclination between a direction between support points connecting a support point of the workpiece by the headstock and a support point of the workpiece by the tailstock and the reference Z axis. The grinding machine described in 1. The wheel head moves relative to the Z-axis direction along a wheel head guide provided on the bed,
The grinding machine according to claim 2, wherein the Z-axis direction inclination of the wheel head is an inclination of the guide for the wheel head with respect to the reference Z axis. The first displacement monitoring means or the second displacement monitoring means,
A temperature sensor for detecting the temperature of the headstock or the tailstock,
Relationship storage means for storing in advance a first relationship or a second relationship between the temperature of the headstock or the tailstock and the amount of thermal displacement in the X-axis direction of the absolute coordinate system;
Displacement estimation for estimating the relative displacement of the headstock or the tailstock based on the temperature detected by the temperature sensor and the first relation or the second relation stored in the relation storage means Means,
A grinding machine according to any one of claims 1 to 4. The third displacement monitoring means includes
A temperature sensor for detecting a temperature in the vicinity of the grinding wheel platform or the grinding wheel platform;
Relationship storage means for storing in advance a third relationship between the temperature of the grinding wheel platform or the vicinity of the grinding wheel platform and the amount of thermal displacement in the absolute coordinate system X-axis direction;
Displacement estimation means for estimating the relative displacement of the grindstone table based on the temperature detected by the temperature sensor and the third relation stored in the relation storage means;
A grinding machine according to claim 2.   The grinding machine according to any one of claims 1 to 4, wherein the first displacement monitoring unit and the second displacement monitoring unit are displacement sensors.   The grinding machine according to claim 7, wherein the first displacement monitoring unit monitors the relative displacement of the headstock with respect to the bed at a support point of the workpiece.   The grinding machine according to claim 7, wherein the first displacement monitoring means monitors the relative displacement with respect to the bed in a reference seat provided on the headstock.   The grinding machine according to claim 7, wherein the second displacement monitoring means monitors the relative displacement of the tailstock with respect to the bed at a support point of the workpiece.   The grinding machine according to claim 7, wherein the second displacement monitoring means monitors the relative displacement of the reference seat provided on the tailstock with respect to the bed.   The grinding machine according to any one of claims 2 and 4, wherein the third displacement monitoring means is a displacement sensor. Bed and
A headstock and a tailstock mounted on the bed and supporting both ends of the workpiece;
A whetstone base placed on the bed and movable relative to the headstock and the tailstock in the X-axis direction and the Z-axis direction and relative to the bed in the Z-axis direction;
Third displacement monitoring means for constantly monitoring relative displacement in the absolute coordinate system X-axis direction of the grindstone table with respect to the bed;
An inclination calculating means for calculating an inclination in the Z-axis direction in which the grindstone table moves with respect to a preset reference Z-axis based on the relative displacement of the grindstone table;
Correction means for correcting a taper error of the workpiece based on the inclination in the Z-axis direction of the grindstone table;
A grinding machine comprising: The third displacement monitoring means includes
A temperature sensor for detecting a temperature in the vicinity of the grinding wheel platform or the grinding wheel platform;
Relationship storage means for storing in advance a third relationship between the temperature of the grinding wheel platform or the vicinity of the grinding wheel platform and the amount of thermal displacement in the absolute coordinate system X-axis direction;
Displacement estimation means for estimating the relative displacement of the grindstone table based on the temperature detected by the temperature sensor and the third relation stored in the relation storage means;
A grinding machine according to claim 13.   The grinding machine according to claim 13, wherein the third displacement monitoring means is a displacement sensor. Grinding is performed by relatively moving the grindstone table placed on the bed in the X-axis direction and the Z-axis direction with respect to the work supported at both ends by the headstock and the tailstock placed on the bed. A grinding method to perform,
Constantly monitoring the relative displacement of the headstock in the X-axis direction of the absolute coordinate system with respect to the bed,
Constantly monitoring the relative displacement of the tailstock in the absolute coordinate system X-axis direction with respect to the bed,
Based on the relative displacement of the headstock and the relative displacement of the tailstock, the inclination of the workpiece axis with respect to a preset reference Z-axis is calculated,
A grinding method, wherein a taper error of the workpiece is corrected based on an inclination of the workpiece axis. Grinding is performed by relatively moving the grindstone table placed on the bed in the X-axis direction and the Z-axis direction with respect to the work supported at both ends by the headstock and the tailstock placed on the bed. A grinding method to perform,
The relative displacement in the absolute coordinate system X-axis direction of the grindstone table is constantly monitored with respect to the bed,
Based on the relative displacement of the grinding wheel platform, the inclination of the Z axis direction in which the grinding wheel platform moves with respect to a preset reference Z axis is calculated,
A grinding method, wherein a taper error of the workpiece is corrected based on the tilt in the Z-axis direction of the grindstone table.

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