JP2017117282A - Machine tool and control method of machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machine tool that can perform processing accurately under numerical control even when the attachment position of an additional rotary unit is displaced, and a control method of the machine tool.SOLUTION: A machine tool comprises: a machine main body 100 including a rotatable table 13, a tool that processes a workpiece, a main shaft 19 on which the tool is mounted, a feed shaft that drives a three-dimensional orthogonal coordinate system, and an additional rotary unit 17 that fixes a removably attachable workpiece onto the table 13; and a numerical control device that numerically controls the machine main body 100. The machine tool determines the amount of displacement in position of the additional rotary unit 17 from a reference point to which the additional rotary unit 17 is essentially attached, corrects the displacement amount, and performs numerical control.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a machine tool such as a horizontal lathe and a method for controlling the machine tool.

  A horizontal lathe is known as a machine tool for performing a lathe. A horizontal center lathe places a work on a table, gives a rotary motion to a centering tool attached to the spindle, and performs numerical control to place the tool at a desired position with respect to the work. It is a machine that moves and performs intermediate-feed machining.

  As a conventional horizontal lathe, for example, one disclosed in Patent Document 1 is known. Patent Document 1 discloses that when the ram tip is bent due to its own weight, machining is performed at an appropriate angle by correcting the inclination angle of the ram using a hydraulic cylinder. Here, generally used horizontal lathes place and fix a workpiece on a table, move the workpiece and tool relatively in a three-dimensional direction, and machine a desired part of the workpiece by numerical control. To do.

JP 2011-121157 A

  On the other hand, depending on the workpiece processing mode, there may be employed a method in which an additional rotary unit is mounted on a table and the workpiece is fixed to the additional rotary unit. In such a case, since it is necessary to fix the additional rotary unit (mounting unit) to the table, the additional rotary unit is attached to and detached from the table as necessary. However, since the operation of attaching the additional rotary unit to the table is performed manually by the operator, there is a problem that it takes a long time to attach it with high accuracy.

  The present invention has been made to solve such a conventional problem, and the object of the present invention is to perform machining by numerical control with high accuracy even when there is a deviation in the mounting position of the additional rotary unit. Accordingly, it is an object of the present invention to provide a machine tool and a method for controlling the machine tool that can reduce the installation work by an operator.

  In order to achieve the above object, a machine tool according to claim 1 of the present application includes a rotatable table, a tool for machining a workpiece, a spindle on which the tool is mounted, and a feed axis driven in a three-dimensional orthogonal coordinate system. A mounting unit that fixes the work that can be attached to and detached from the table, and a positional deviation amount detection unit that detects a positional deviation amount between the mounting unit and a reference point that should be originally attached, And a numerical control device that numerically controls the machine main body by correcting the coordinates at the time of workpiece machining using the positional deviation amount detected by the positional deviation amount detection unit.

  A machine tool according to a second aspect is the machine tool according to the first aspect, wherein the mounting unit is erected on the surface of the table, and the axial direction of the main shaft is set as a first axis, and the misalignment detection unit is When the table rotation position is set so that the surface of the mounting unit is orthogonal to the first axis, two measurements parallel to the table surface separated by a distance L1 from the surface of the mounting unit A point is set, and a distance in the first axial direction from the main axis to one measurement point and a distance in the first axial direction from the main axis to the other measurement point are measured, and a distance difference ΔL is calculated. Further, based on the distance L1 and the difference ΔL, a deviation angle θ between the reference axis that is the center line of the opening formed in the mounting unit and the first axis is calculated, and the deviation angle θ is calculated. The positional deviation amount is used.

  A machine tool according to a third aspect is the machine tool according to the first or second aspect, wherein the mounting unit is erected on the surface of the table and includes the circular opening, and the axial direction of the main shaft is further The position deviation amount detection unit is attached to the main shaft when the rotational position of the table is set so that the surface of the attachment unit is orthogonal to the first axis. The touch sensor is slid to one of the second axes orthogonal to the first axis in the opening to obtain a first coordinate that is a position in contact with the opening, and the second axis The second coordinate which is a position in contact with the opening by sliding to the other is obtained, and further, the second coordinate in the second axial direction of the center position of the opening from the first coordinate and the second coordinate. From this coordinate, the original mounting unit Determine the amount of positional deviation between the reference point to be kicked, characterized in that the offset amount of the first axis.

  A machine tool according to a fourth aspect is the machine tool according to the third aspect, wherein the positional deviation amount detection unit slides the touch sensor to one of the third axes that are perpendicular to the table surface within the opening. To obtain a third coordinate that is a position in contact with the opening, and to obtain a fourth coordinate that is a position in contact with the opening by sliding to the other of the third axes, and The coordinate of the third axial direction of the center position of the opening is obtained from the coordinates of 3 and the fourth coordinate, the amount of positional deviation from the reference point that should be originally attached to the attachment unit is obtained from this coordinate, The offset amount of the shaft is used.

  A machine tool according to a fifth aspect of the present invention is the machine tool according to any one of the first to fourth aspects, wherein the machine tool is a horizontal center lathe, and the workpiece is machined by attaching a tool to the spindle.

  A machine tool control method according to claim 6 is a machine tool control method for performing numerical control by attaching a mounting unit for placing a work on a rotatable table and fixing the work, wherein the mounting unit The step of setting the rotational position of the table so that the surface of the surface is perpendicular to the first axis which is the axial direction of the main axis, and between two measurement points parallel to the table surface set on the surface of the mounting unit And calculating a difference ΔL between a distance in the first axial direction from the main axis to the one measurement point and a distance in the first axial direction from the main axis to the other measurement point, and the distance L1 And calculating the deviation angle θ between the reference axis that is the center line of the opening formed in the mounting unit and the first axis based on the difference ΔL, and using the deviation angle θ. Correct the coordinates when machining the workpiece. And performing a numerical control, characterized by comprising a.

  A control method for a machine tool according to a seventh aspect is the method according to the sixth aspect, wherein the touch sensor attached to the main shaft is slid to one of the second shafts orthogonal to the axial direction of the main shaft in the opening, Obtaining a first coordinate which is a position in contact with the opening, and sliding in the other direction of the second axis in the opening to obtain a second coordinate which is a position in contact with the opening. A step of obtaining a center coordinate in the second axial direction of the opening from the first coordinate and a second coordinate, and the center coordinate in the second axial direction of the opening. A step of obtaining a positional deviation amount with respect to a reference point to be originally attached to the mounting unit, and a step of performing numerical control by correcting the coordinates at the time of workpiece machining using the positional deviation amount; To do.

  A method for controlling a machine tool according to an eighth aspect is the method according to the sixth or seventh aspect, wherein the touch sensor is slid to one of the third shafts in a direction perpendicular to the table surface in the opening, and the opening A step of obtaining a third coordinate which is a position in contact with the portion, and a fourth coordinate which is a position in contact with the opening by sliding in the other direction of the third axis in the opening. A step of obtaining a center coordinate in the third axial direction of the opening from the third coordinate and the fourth coordinate, and the attachment based on the center coordinate in the third axial direction of the opening. A step of obtaining a positional deviation amount with respect to a reference point to be originally attached to the unit, and a step of performing numerical control by correcting coordinates at the time of workpiece machining using the positional deviation amount. .

FIG. 1 is a perspective view schematically showing the configuration of a horizontal lathe that is a machine tool according to an embodiment of the present invention, and shows a state in which an additional rotary unit is not attached. FIG. 2 is a perspective view schematically showing a configuration of a horizontal boring machine that is a machine tool according to an embodiment of the present invention, and shows a state where an additional rotary unit is attached. FIG. 3 is a flowchart showing a process of calculating a deviation angle of the additional rotary unit in the horizontal center lathe that is the machine tool according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing a positional relationship with the main shaft when the table on which the additional rotary unit is mounted is rotated by 90 °. FIG. 5 shows the deviation angle θ of the additional rotary unit, (a) shows two points q1 and q2, and (b) is an explanatory diagram showing the relationship between the distance L1 and the differences ΔL and θ. FIG. 6 is a flowchart showing a process of calculating the X coordinate and the Y coordinate of the center position of the additional rotary unit in the machine tool according to the embodiment of the present invention. FIG. 7 is an explanatory diagram showing a positional deviation between the reference axis of the additional rotary unit and the axial direction of the main shaft. FIG. 8 is an explanatory diagram showing the X coordinate of the reference position.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view schematically showing the configuration of a horizontal boring machine 100 that is a machine tool according to an embodiment of the present invention. As shown in FIG. 1, the horizontal lathe 100 according to the present embodiment has a rectangular parallelepiped bed 11 (support) whose upper surface is a horizontal plane. An X axis (second axis) and a Z axis (first axis) that are orthogonal to each other are set on the upper surface of the bed 11, and a direction that is orthogonal to the upper surface (normal direction). Is set to the Y-axis (third axis).

  A saddle 12 is provided on the upper surface of the bed 11 so as to be slidable in the Z-axis direction. That is, a guide rail (not shown) is provided on the upper surface of the bed 11 along the Z-axis direction, and the saddle 12 is slidably supported along the guide rail.

  On the upper surface of the saddle 12, a flat plate-like table 13 that can slide in the X-axis direction with respect to the saddle 12 is provided. A work (not shown) to be processed is placed on the table 13. The table 13 is rotatable about the center point Q. This rotation direction is taken as the B axis. In addition, since the slide mechanism and rotation mechanism of the table 13 are well-known techniques, description is abbreviate | omitted.

  On the other hand, the bed 11 is provided with a column 14 in a direction orthogonal to the bed 11, and the column 14 is provided with a spindle head 15 that can slide in the vertical direction (Y-axis direction). ing. A spindle 19 is mounted on the spindle head 15, and various tools used for machining a workpiece can be attached to the spindle 19. Moreover, it is also possible to attach a touch sensor as needed.

  Therefore, when the bed 11 is used as a reference, the saddle 12 can slide in the Z-axis direction relative to the bed 11, and the table 13 can slide in the X-axis direction relative to the saddle 12. Further, the table 13 can rotate in the B-axis direction, and the spindle head 15 can slide in the Y-axis direction with respect to the bed 11.

  Therefore, the bed 11, the saddle 12, the table 13, and the spindle head 15 are numerically controlled to determine the machining position by the tool attached to the spindle 19, and further, the tool is driven and placed on the table 13. The workpiece can be processed.

  Further, the horizontal rotary lathe 100 according to the present embodiment can attach the additional rotary unit 17 (attachment unit) on the table 13. That is, the additional rotary unit 17 can be attached to and detached from the table 13. FIG. 2 shows a state where the additional rotary unit 17 is erected and fixed at a predetermined position on the table 13. The additional rotary unit 17 has a circular opening 18 at the center. Further, the opening 18 is provided with a rotation mechanism (not shown), and the work fixed to the opening 18 can be rotated with reference to the direction of arrow A in FIG. Further, an axis that is orthogonal to the additional rotary unit 17 and passes through the center of the opening 18 is set as the reference axis M <b> 1 of the additional rotary unit 17.

  Normally, the additional rotary unit 17 is removed from the table 13 as shown in FIG. 1, and the additional rotary unit 17 is installed on the upper surface of the table 13 as shown in FIG. That is, the additional rotary unit 17 is attached to the upper surface of the table 13 as shown in FIG. The additional rotary unit 17 can be attached to an attachment site set on the table 13, and is usually attached and removed manually by an operator.

  In addition, the horizontal lathe 100 according to the present embodiment includes a main control unit 20 that comprehensively controls workpiece machining. Further, the main control unit 20 has a function as a numerical control device that drives a tool mounted on the spindle 19 by numerical control (NC control) and processes a workpiece placed on the table 13. The main control unit 20 also includes a reference axis M1 of the additional rotary unit 17 and a Z axis (first axis) that is one of two axes that define the two-dimensional coordinates of the surface of the table 13. A function as a positional deviation amount detection unit for detecting the positional deviation amount (deviation angle θ) is provided. Further, the main control unit 20 includes an offset amount (offset Zao) that is a positional deviation amount in the axial direction (Z-axis) of the main shaft 19 at the mounting position of the additional rotary unit 17 and the Y-axis direction of the mounted state of the additional rotary unit 17 It also has a function as a misregistration amount detection unit that detects an offset amount (offset Yao), which is the misregistration amount. Moreover, it has the function as a numerical control apparatus which performs numerical control based on those positional offset amounts. The main control unit 20 can be configured as an integrated computer including a central processing unit (CPU) and storage means such as a RAM, a ROM, and a hard disk.

  Here, since the additional rotary unit 17 is mounted on the table 13 manually by the operator, it is not always mounted at the same position. In the present embodiment, the reference point at which the additional rotary unit 17 should be originally attached from the deviation angle θ of the reference axis M1 that is the center line of the opening 18 of the additional rotary unit 17 and the three-dimensional coordinates of the center position N1 of the opening 18. The amount of offset from is calculated. Then, the main control unit 20 performs numerical control using the deviation angle θ and the offset amount.

[Calculation of deviation angle θ]
First, a deviation angle θ, which is an angle formed by the reference axis M1 and the Z axis, is obtained. The procedure for calculating the deviation angle θ will be described with reference to the flowchart shown in FIG. 3 and the explanatory diagrams shown in FIGS. As shown in FIG. 2, when the additional rotary unit 17 is positioned on the left side of the table 13 and the table 13 is rotated 90 ° in the negative direction of the B-axis (opposite the arrow), it is shown in FIG. 4. As described above, the reference axis M <b> 1 of the additional rotary unit 17 faces the Z-axis direction that is the axial direction of the main shaft 19.

  In step S <b> 11 of FIG. 3, the main control unit 20 sets arbitrary two points q <b> 1 and q <b> 2 (measurement points) on the surface of the additional rotary unit 17. At this time, the straight line connecting the points q 1 and q 2 is set to be parallel to the surface of the table 13. Specifically, points q1 and q2 shown in FIG. The distance between the points q1 and q2 (the distance between the measurement points) is known and is assumed to be the distance L1.

  Next, the touch sensor 21 (see FIG. 4) is attached to the tip of the main shaft 19. In step S12, the main control unit 20 moves the main shaft 19 in the Z-axis direction, thereby determining the distance from the front end portion of the main shaft 19 to the point q1 and the distance from the front end portion of the main shaft 19 to the point q2. taking measurement.

  In step S13, a difference between the two distances measured in the process of step S12 is calculated, and this is set as a difference ΔL. Therefore, as shown in FIG. 5B, the relationship between the distance L1 between the points q1 and q2 and the difference ΔL is obtained.

In step S14, using the distance L1 and the difference ΔL, the deviation angle θ is obtained by the following equation (1).
θ = tan ⁻¹ (ΔL / L1) (1)

  As a result, the shift angle θ (position shift amount) between the reference axis M1 and the Z axis of the additional rotary unit 17 shown in FIG. 4 can be obtained. In step S15, the main control unit 20 acquires the deviation angle θ.

[Calculation of three-dimensional coordinates of center position N1 and offset amount]
Next, the procedure for calculating the three-dimensional coordinates of the center position N1 of the opening 18 formed in the additional rotary unit 17 will be described with reference to the flowchart shown in FIG. 6 and the explanatory diagrams shown in FIGS. To do. First, in step S31 of FIG. 6, the table 13 is rotated in the B-axis direction so that the reference axis M1 of the additional rotary unit 17 is at a position rotated by a deviation angle θ with respect to the Z-axis. Specifically, as shown in FIG. 7, the table 13 is rotated by the shift angle θ. As a result, the directions of the reference axis M1 and the Z axis (the axial direction of the main shaft 19) coincide, and the surface of the additional rotary unit 17 and the Z axis are orthogonal.

  In step S <b> 32, the touch sensor 21 is attached to the tip of the main shaft 19, and the touch sensor 21 is inserted into the opening 18 formed in the additional rotary unit 17. In step S33, the table 13 is moved to one side (for example, the plus side) of the X axis while the touch sensor 21 is positioned in the opening 18. As a result, the sensor comes into contact with the inner surface of the opening 18. The coordinate in the X-axis direction at this time is stored as x1 (first coordinate).

  In step S34, the table 13 is moved to the other side (for example, the minus side) in the X-axis direction. As a result, the sensor comes into contact with the inner surface on the other side of the opening 18. The coordinates in the X-axis direction at this time are stored as x2 (second coordinates).

In step S35, based on the two X coordinates x1 and x2, the X coordinate x0 (that is, the center coordinate of the opening 18) of the reference axis M1 is obtained by the following equation (2).
x0 = (x1 + x2) / 2 (2)
That is, as shown in FIG. 8, the coordinate x0 is the X coordinate of the center position N1, and the offset amount from the reference point (xr, yr, zr, br) to which the additional rotary unit 17 should be originally attached is set. It calculates | requires by Zao = xzr-x0 (refer step S41). This value is set as an offset Zao with respect to the Z-axis reference point of the additional rotary unit 17. Here, “xzr” indicates the X coordinate of the center of the opening of the additional rotary unit 17 when the B-axis is rotated 90 ° in the minus direction in a state where the additional rotary unit 17 is supposed to be attached.

  In step S36, the main control unit 20 recognizes that the X coordinate of the center position N1 is x0.

  In step S37, the main shaft 19 is moved to one side (for example, the upper side) in the Y-axis direction. As a result, the sensor comes into contact with the inner surface on one side of the opening 18. The coordinates in the Y-axis direction at this time are stored as y1 (third coordinates).

  In step S38, the table 13 is moved to the other side (for example, the lower side) in the Y-axis direction. As a result, the sensor comes into contact with the inner surface on the other side of the opening 18. The coordinates in the Y-axis direction at this time are stored as y2 (fourth coordinates).

In step S39, based on the two Y coordinates y1 and y2, the coordinate y0 in the Y-axis direction of the reference axis M1 (that is, the center coordinate of the opening 18) is obtained by the following equation (3).
y0 = (y1 + y2) / 2 (3)
From this value, the offset amount from the reference point where the additional rotary unit 17 should be originally attached is obtained by Yao = yr−y0 (see step S42). This value is set as an offset Yao with respect to the Y-axis reference point of the additional rotary unit 17.

  In step S40, the main control unit 20 recognizes that the Y coordinate of the center position N1 is y0.

  The shift angle θ and the offsets Zao and Yao were obtained by the above processing. Therefore, the main control unit 20 can process the workpiece with the same program even when the additional rotary unit 17 is reattached by correcting the numerical control device using these data. If correction cannot be performed by the numerical control device, the data can be read by the operator, for example, by setting it in a macro variable, and the data is input to the 5-axis machining program output CAM, and the program is output from the CAM. Can be processed.

  Thus, in the horizontal center lathe 100 according to the present embodiment, the amount of positional deviation from the reference point where the additional rotary unit 17 should be originally attached is obtained, and the main control unit 20 is based on this positional deviation amount data. Thus, the workpiece can be machined without changing the program. If the main control unit 20 cannot correct the program, the data can be read by setting the data in a macro variable so that the operator can read it, and the program is output to the 5-axis machining program output CAM and output from the CAM. It becomes possible to machine the workpiece. Therefore, when performing numerical control by the main control unit 20, even if there is a slight shift in the attachment position of the additional rotary unit 17, the workpiece is processed by high-precision numerical control using this positional shift amount. It becomes possible to carry out.

  For this reason, when the operator mounts the additional rotary unit 17 on the table 13, it is not necessary to perform high-precision alignment, and it is possible to mount the additional rotary unit 17 in a state where there is a slight displacement. As a result, even when the additional rotary unit 17 needs to be frequently attached and detached, the loss of work time can be reduced.

  As mentioned above, although the machine tool of this invention and the control method of the machine tool were demonstrated based on embodiment of illustration, this invention is not limited to this, The structure of each part is the arbitrary which has the same function. It can be replaced with a configuration one.

  For example, in the above-described embodiment, the horizontal lathe 100 has been described as an example of a machine tool. However, the present invention is not limited to this, and has other detachable attachment units. It can be applied to machine tools.

11 Bed 12 Saddle 13 Table 14 Column 15 Spindle Head 17 Additional Rotary Unit 18 Opening 19 Spindle 20 Main Control Unit (Numerical Control Device, Misalignment Detection Unit)
21 Touch sensor 100 Horizontal lathe

Claims (8)

A rotatable table,
A tool for machining a workpiece;
A spindle on which the tool is mounted;
A feed axis driven in a three-dimensional orthogonal coordinate system;
An attachment unit for fixing the detachable work on the table;
A machine body comprising:
A displacement amount detection unit for detecting a displacement amount of the mounting unit with respect to a reference point that should be originally attached;
A numerical control device that numerically controls the machine body by correcting the coordinates at the time of workpiece machining using the positional deviation amount detected by the positional deviation amount detection unit;
A machine tool comprising: The mounting unit is erected on the table surface, and the axial direction of the main shaft is set as a first axis;
The positional deviation amount detection unit is configured such that the table separated by a distance L1 from the surface of the mounting unit when the rotational position of the table is set so that the surface of the mounting unit is at a position orthogonal to the first axis. Two measurement points parallel to the surface are set, and the distance in the first axial direction from the main axis to one measurement point and the distance in the first axial direction from the main axis to the other measurement point are measured. The distance difference ΔL is calculated, and the deviation angle θ between the reference axis that is the center line of the opening formed in the mounting unit and the first axis is calculated based on the distance L1 and the difference ΔL. The machine tool according to claim 1, wherein the deviation angle θ is set as the positional deviation amount. The mounting unit is erected on the table surface and includes the circular opening, and the axial direction of the main shaft is set to the first axis,
The positional deviation amount detection unit has a touch sensor attached to the main shaft in the opening when the rotational position of the table is set so that the surface of the attachment unit is perpendicular to the first axis. The first coordinate that is the position in contact with the opening is obtained by sliding to one of the second axes orthogonal to the first axis, and the second coordinate is slid to the other of the second axes. A second coordinate which is a position in contact with the opening is obtained, and further, a coordinate in the second axial direction of the center position of the opening is obtained from the first coordinate and the second coordinate. The machine tool according to claim 1 or 2, wherein an amount of displacement of the mounting unit from a reference point to be originally mounted is obtained and set as an offset amount of the first shaft. The positional deviation amount detection unit is a third coordinate that is a position in which the touch sensor is slid in one of the third axes that are perpendicular to the table surface in the opening and is in contact with the opening. And the fourth coordinate which is a position in contact with the opening by sliding to the other of the third axes is obtained, and further, the third coordinate and the fourth coordinate are used to determine the position of the opening. The coordinate in the third axial direction of the center position is obtained, the amount of positional deviation from the reference point to which the attachment unit should be attached is obtained from this coordinate, and the offset amount of the third axis is obtained. The machine tool described in 1. The machine tool according to any one of claims 1 to 4, wherein the machine tool is a horizontal center lathe, and the workpiece is machined by attaching a tool to the spindle. A machine tool control method for performing numerical control by attaching a mounting unit for mounting a work on a rotatable table and fixing the work.
Setting the rotational position of the table so that the surface of the mounting unit is at a position orthogonal to the first axis which is the axial direction of the main shaft;
A distance L1 between two measurement points parallel to the table surface set on the surface of the mounting unit;
Calculating a difference ΔL between a first axial distance from the main axis to one measurement point and a first axial distance from the main axis to the other measurement point;
Calculating a deviation angle θ between a reference axis that is a center line of the opening formed in the mounting unit and the first axis based on the distance L1 and the difference ΔL;
Using the deviation angle θ, correcting the coordinates at the time of workpiece machining and performing numerical control;
A machine tool control method comprising: Sliding the touch sensor attached to the main shaft to one of the second axes orthogonal to the axial direction of the main shaft in the opening, and obtaining first coordinates that are in contact with the opening; and
In the opening, sliding in the other direction of the second axis to obtain a second coordinate that is a position in contact with the opening;
Obtaining a central coordinate in the second axial direction of the opening from the first coordinate and the second coordinate;
Obtaining a positional deviation amount with respect to a reference point to which the attachment unit should be originally attached based on a central coordinate of the opening in the second axial direction;
Using the positional deviation amount, correcting the coordinates at the time of workpiece machining and performing numerical control;
The machine tool control method according to claim 6, further comprising: Sliding the touch sensor to one of the third axes in a direction perpendicular to the table surface in the opening to obtain a third coordinate that is a position in contact with the opening;
In the opening, sliding in the other direction of the third axis to obtain a fourth coordinate that is a position in contact with the opening;
Obtaining center coordinates in the third axial direction of the opening from the third coordinates and the fourth coordinates;
Obtaining a positional deviation amount with respect to a reference point to be originally attached to the attachment unit based on a center coordinate of the opening in the third axial direction;
Using the positional deviation amount, correcting the coordinates at the time of workpiece machining and performing numerical control;
The machine tool control method according to claim 6 or 7, further comprising:

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