Working machinery

Abstract

To provide a machine tool that includes multiple adjustment processes for the reciprocating movement of a linear drive unit. [Solution] A machine tool comprising: a plurality of linear drive units that move a tool post equipped with a tool in a predetermined axial direction; and a control device that controls the movement of the tool by a combination of linear movements in each axial direction of the linear drive units, wherein the control device performs a main process at a predetermined timing to move the tool post back and forth within a predetermined range for each axial linear drive unit, and a sub-process to adjust quadrant switching parameters that reverse the direction of movement of the other linear drive units during the main process in one axial direction of the plurality of linear drive units.

Description

Technical Field

[0001] The present invention relates to a machine tool that executes adjustment processing related to a linear drive unit.

Background Art

[0002] In order to perform machining on a workpiece held by a spindle device, a machine tool performs drive control to move a corresponding tool to a machining position. At that time, a tool rest equipped with a tool moves by a linear motion along a plurality of rails, and positioning of the tool at a predetermined machining position is performed. Such a linear drive unit is provided in a machine tool for machining a plurality of workpieces, and the tool rest reciprocates repeatedly. At that time, in order to enable smooth movement of the tool rest, lubricating oil is supplied to the sliding portion. Although the lubricating oil remains on the sliding surface to some extent due to its viscosity, it flows out from the sliding surface with repeated workpiece machining. Therefore, for example, in Patent Document 1 below, a recess formed on the sliding surface functions as an oil reservoir for lubricating oil, and by making it easier to hold the lubricating oil on the sliding surface, a machine tool that can smoothly slide the tool rest is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the tool post repeatedly moves back and forth in the same position, lubricating oil flows out from the sliding surface within the range of movement, but it accumulates outside the range of movement, especially at the turning points where the direction changes. If this accumulation of lubricating oil in a particular area is left unattended, it may have an effect when the movement control range is changed during subsequent setup changes. Therefore, adjustment processes such as periodically moving the tool post beyond the control range during machining are performed to spread the lubricating oil that has accumulated in a part of the linear drive unit, or to agitate the lubricating oil. However, until now, reciprocating movement beyond the control range of an object such as a tool post has only been for the purpose of one adjustment process, such as spreading the lubricating oil.

[0005] Therefore, the present invention aims to provide a machine tool that includes multiple adjustment processes for the reciprocating movement of a linear drive unit in order to solve these problems. [Means for solving the problem]

[0006] The machine tool according to the present invention comprises a plurality of linear drive units that move a tool post equipped with a tool in a predetermined axial direction, and a control device that controls the movement of the tool by a combination of linear movements in each axial direction of the linear drive units, wherein the control device performs, at a predetermined timing, a main process that causes the tool post to reciprocate within a predetermined range for each axis of the linear drive units, and a sub-process that adjusts quadrant switching parameters that reverse the direction of movement of the other linear drive units during the main process in one axial direction of the plurality of linear drive units. [Effects of the Invention]

[0007] According to the above configuration, the control device controls the linear drive unit to move the tool post equipped with the tool in a predetermined axial direction, thereby enabling machining of the workpiece. Furthermore, even if lubricating oil accumulates due to repeated linear movement, the control device performs a main process at a predetermined timing for each linear drive unit in each axial direction, reciprocating the tool post within a predetermined range for each axis, thereby performing an adjustment process such as spreading the accumulated lubricating oil. In addition, by executing a sub-process during the main process in one axial direction of one of the multiple linear drive units, the control device can perform parameter adjustment processing related to quadrant switching when the direction of movement of other linear drive units reverses. [Brief explanation of the drawing]

[0008] [Figure 1] This is a simplified front view showing one embodiment of a machine tool. [Figure 2] This is a block diagram showing a control system for controlling machine tools. [Figure 3] This is an illustrative diagram showing the trajectory of a tool used to machine a workpiece into an arc shape. [Figure 4] This graph shows the position of the tool rest in the X-axis direction as it changes over time, following an arc-shaped trajectory. [Figure 5] This diagram shows a flowchart of the stirring process program. [Figure 6] This is a flowchart showing the parameter adjustment process program for quadrant switching. [Modes for carrying out the invention]

[0009] An embodiment of the machine tool according to the present invention will be described below with reference to the drawings. Figure 1 is a simplified front view of the machine tool of this embodiment. In this machine tool 1, the bed 2 is supported by leveling blocks arranged in four locations on the front, rear, left, and right sides, and the machine is configured to be leveled by adjusting the height of each of them. In the machine tool 1, various machining devices such as the spindle unit 3 and turret unit 4 mounted on the bed 2 are covered by a machine cover (not shown), and a closed machining chamber is formed in which coolant is sprayed during machining.

[0010] The spindle unit 3 of the machine tool 1, which is a single-axis lathe, is configured such that the direction of the center of the spindle is the machine width direction, which is the longitudinal direction of the bed 2. Therefore, in this embodiment, the machine width direction parallel to the spindle will be described as the Z-axis, and the vertical direction of the machine perpendicular to the Z-axis will be described as the X-axis. The spindle unit 3 is configured such that a spindle chuck 11 for gripping a workpiece is rotatably provided, and rotation is imparted to the workpiece gripped by the spindle chuck 11 by the drive of a spindle motor. On the other hand, the turret unit 4 is configured such that a plurality of tools are detachably attached to the tool post 12, and a predetermined tool can be selected by swivel indexing according to the machining content.

[0011] The turret device 4 is equipped with linear drive units 40 in the Z-axis and X-axis directions (see Figure 2) so that the tool on the tool post 12 can move to the machining position relative to the workpiece. Specifically, the tool post 12 is assembled to a device body 14 equipped with a swivel mechanism, and the device body 14 is configured to slide along a guide rail 13 in the Z-axis direction that is fixed to the bed 2. Furthermore, the device body 14, which is slidable by the linear guide, can be controlled to move in the Z-axis direction along the guide rail 13 by a ball screw mechanism that converts the rotation of the Z-axis servo motor 41 into linear motion. In addition, the tool post 12 uses a linear guide that slides along an X-axis direction guide rail 15 fixed to the device body 14, and the slidable tool post 12 can be controlled to move in the X-axis direction along the guide rail 15 by a ball screw mechanism that converts the rotation of the X-axis servo motor 42 into linear motion.

[0012] Figure 2 is a block diagram showing the control system for the machine tool 1. The control device 5 of the machine tool 1 is connected to a microprocessor (CPU) 21, ROM 22, RAM 23, and non-volatile memory 24 via a bus line. The CPU 21 provides overall control of the control device, the ROM 22 stores system programs and control parameters executed by the CPU 21, and the RAM 23 stores temporary calculation data and display data. The non-volatile memory 24 stores information necessary for processing performed by the CPU 21, including the machining control program for the machine tool 1 and the stirring process program described later.

[0013] The control device 5 is equipped with an I / O port 25, through which the drive motors of the spindle unit 3 and the turret unit 4 are connected via drivers. An operation display device 6 is also connected to the I / O port 25. The operation display device 6 includes various operation buttons and switches, as well as a touch-panel monitor that displays various information such as the operation screen and operating status. The operation display device 6 functions as an input interface for operating each device, and as an input interface for acquiring various drive control programs and operating parameters.

[0014] In the machining of a workpiece in machine tool 1, the workpiece is transported into the machining chamber by a workpiece transporter (not shown) and transferred to the spindle chuck 11 of the spindle unit 3. In the turret unit 2, the tool on the tool post 12 is rotated and indexed, and the unit body 12 slides along the guide rail 13 in the Z-axis direction by the linear drive unit 40, and the tool post 12 also slides in the X-axis direction via the guide rail 15 provided on the unit body 14. Then, the tool is applied to the phase-aligned workpiece in the spindle unit 3, or to the rotating workpiece, and the predetermined machining is performed. After that, the machined workpiece is removed and sent to the next process, while a new workpiece is brought in and transferred to the spindle chuck 11.

[0015] In machine tool 1, the same workpiece is subjected to a large volume of machining operations. As a result, the tool post 12 repeatedly moves back and forth between the origin position, which is far from the spindle unit 3, and the machining position. As mentioned in the problem above, lubricating oil accumulates at each turning point in the linear drive unit 40. The lubricating oil that has accumulated in one area needs to be spread out so as not to affect machining after the changeover. Therefore, according to the stirring process program stored in the non-volatile memory 24, the sliding member that slides along the guide rails 13 and 15 is repeatedly moved back and forth in a linear motion, and a stirring operation is performed to spread the lubricating oil that has accumulated in one area throughout.

[0016] In the agitation program, the tool post 12 is periodically moved back and forth over a wide range (preferably the maximum possible range) in the Z-axis and X-axis directions to disperse the lubricating oil. The range of movement extends beyond the lubricating oil reservoir and basically covers the entire stroke, but the range within the machine that does not interfere varies depending on the dimensions of the tool attached to the tool post 12. Therefore, the movable range is calculated based on the tool's dimensional data, and the range of movement of the tool post 12 in that state is determined. The timing of the agitation operation is such as when the machine tool 1 is powered on at the beginning of the day or when it is powered on after maintenance is completed. On the other hand, if a workpiece is gripped in the spindle chuck 11, the agitation operation is restricted from being performed.

[0017] The stirring process program of this embodiment is not simply configured to repeat the reciprocating movement of the tool rest 12, but is configured to simultaneously adjust the parameters of quadrant switching during linear movement. Here, FIG. 3 is an image diagram showing the trajectory of a tool for machining a workpiece into an arc shape. In particular, a trajectory K1 regarding the cutting edge of a tool 18 for machining an arc shape on the upper surface of a workpiece (not shown) is shown. In the drive control for this trajectory K1, while moving the tool 18 in the Z-axis direction, movement in the X-axis direction is simultaneously performed in the arc-shaped K1a portion. At that time, although the tool 18 does not change in the moving direction from the right side to the left side (ZL direction) when viewed from the front of the machine body with respect to the Z-axis, with respect to the X-axis, the quadrant switches from the XU direction upward in the machine body to the XD direction downward in the machine body in the arc shape K1a.

[0018] That is, quadrant switching occurs at the apex in the X-axis direction in the drive control of the tool rest 12, and an inversion occurs from the upper XU direction shown in FIG. 3 to the lower XD direction. In such an inversion operation of the tool rest 12, it may cause deterioration of machining due to quadrant protrusions (see "quadrant protrusion 35" shown in FIG. 4) on the machining surface. This quadrant protrusion can occur when resistance occurs when the moving direction of the tool 18 switches from the XU direction to the XD direction and the start after the direction is inverted is delayed. That is, an error may occur in the response to the control command, and as a result, it may occur because the cutting edge of the tool 18 deviates from the set trajectory and bulges outward.

[0019] To eliminate the delay in the reversal of the tool rest 12, that is, the reversal of the X-axis servo motor 42, backlash acceleration correction for correcting the reversal delay has been conventionally performed. According to the backlash acceleration correction, the quadrant protrusion can be suppressed by adjusting the backlash acceleration amount during reversal. However, parameters such as the backlash acceleration amount need to be adjusted according to specific conditions such as the weight of the tool and aging deterioration, and the adjustment work was a heavy burden. In the present embodiment, in consideration of such points, parameter adjustment processing for setting and adjusting the backlash acceleration amount and the backlash acceleration time is performed. Moreover, while the lubricating oil is being agitated by the agitation processing program, the parameter adjustment processing is simultaneously configured to be executed.

[0020] Here, FIG. 4 is a graph showing the position in the X-axis direction of the tool rest 12 moved along the orbit of the arc shape K1a according to the change in time. The value of the X coordinate is calculated based on the signal from the encoder provided in the X-axis servo motor 42. The three graphs shown are graphs when the movement control of the tool rest 12 is performed based on the command value. The solid line graph 31 is the locus when no delay occurs when the movement direction is reversed. On the other hand, the one-dot chain line graph 32 and the two-dot chain line graph 33 are the loci when an error occurs between the actual position and the movement command due to resistance such as frictional force and backlash of the ball screw mechanism when the movement direction is reversed.

[0021] Protrusions (quadrant protrusions) 35 that do not exist in the graph 31 occur in the graphs 32 and 33, which deteriorates the machining of the workpiece. Therefore, it is necessary to suppress the quadrant protrusion 35 by parameter adjustment. The backlash acceleration amount, which is one of the parameters, is a correction value related to the speed command for accelerating the reversal operation in order to delete or reduce the quadrant protrusion 35 with respect to the speed command in the reversal direction when the object such as the tool rest 12 is reversed. And the backlash acceleration time, which is also a parameter, is the time for executing the correction by the backlash acceleration amount.

[0022] The amount and duration of backlash acceleration vary depending on the object, as the resistance generated during reversal differs for each object, resulting in inconsistent operation during quadrant switching. This is because the weight and degree of deterioration of the object differ, as do the size and movement speed of the arc shape K1a in the motion control, which vary depending on the machining process. For example, in the case of the tool post 12, multiple tools 18 can be replaced, so the overall weight changes depending on the machining process of the workpiece. Furthermore, the state of the linear guides and ball screw mechanisms in the Z-axis and X-axis directions is also inconsistent. Therefore, it is preferable to periodically adjust the quadrant switching parameters, and this is incorporated into the periodic lubrication oil stirring operation performed in this embodiment.

[0023] Quadrant switching parameter adjustment involves performing multiple test operations with varying values ​​for backlash acceleration amount and backlash acceleration time. In this embodiment, multiple stirring operations to spread the lubricating oil evenly constitute the test operations. The backlash acceleration amount and backlash acceleration time that result in the smallest position deviation obtained from these test operations are then set as the adjusted values. The position deviation is the difference between the commanded movement position for the movement of the tool post 12 and the actual movement position obtained based on the encoder signal, and is represented as the difference between graph 31 and graphs 32 and 33 as shown in Figure 4.

[0024] Next, Figure 5 shows a flowchart of the stirring process program. First, in the lubricating oil stirring process, it is checked whether the corresponding processing flag is "0" (S101). Since the stirring operation is performed sequentially for the Z axis and X axis, the status of the processing flags for both is checked. If both processing flags are set to "1" (S101: NO), it indicates that the lubricating oil stirring process has already been completed, and the stirring process program terminates. On the other hand, if the processing flag for the preceding Z axis stirring process is "0" (S101: YES), the next step is to check that the spindle chuck 11 is not gripping the workpiece (S102).

[0025] Since the spindle chuck 11 is equipped with a workpiece gripping sensor, if a workpiece is gripped based on the signal from the sensor (S102: NO), the program terminates without performing the agitation process. In this case, it is preferable to provide information to the operator, such as by displaying on the operation display device 6 that the agitation process could not be performed. If the spindle chuck 11 does not grip a workpiece (S102: YES), the agitation operation of the lubricating oil is started for the linear drive unit 40 of the Z axis (S103). That is, the diffusion of lubricating oil is started, causing the tool post 12 to repeatedly reciprocate over the maximum range of movement possible on the guide rail 13 of the Z axis.

[0026] When the lubricating oil agitation operation begins, the parameter adjustment process is executed simultaneously (S104). Figure 6 is a flowchart of the quadrant switching parameter adjustment process program. The parameter adjustment process program is incorporated as a subroutine within the agitation process program that executes the main routine. In the parameter adjustment process, the size (radius R) and movement speed V of the arc shape K1a are first set (S201). The radius R and movement speed V can be set arbitrarily, or they may be predetermined constant values, or values ​​corresponding to the processing content of the workpiece. In particular, the movement speed V is set considering a value suitable for the agitation operation.

[0027] Next, initial values ​​are set for the backlash acceleration amount G and the backlash acceleration time T (S202). The initial values ​​are the lower limit (minimum settable value) of the range of parameters tested in multiple test operations (which also involve agitation of the lubricating oil). Subsequently, the linear drive unit 40 performs the test operation, and the tip of the tool 18 moves along a track K1 that includes an arc shape K1a, as shown in Figure 3 (S203). At this time, as the slide member moves along the track K1, it reciprocates and passes over the lubricating oil reservoir on the guide rail 13, so that the lubricating oil is spread widely on the guide rail 13.

[0028] For each of these test operations, a position deviation is calculated in conjunction with the reversal movement in the X-axis direction performed in the K1a section of the trajectory, and the values ​​of the backlash acceleration amount G and backlash acceleration time T used in that operation, along with the value of the position deviation, are stored in association (S204). That is, in a test operation performed multiple times, the values ​​of the backlash acceleration amount G, backlash acceleration time T, and position deviation for each operation number are stored. Then, for each operation, it is checked whether the backlash acceleration amount G used in the test operation is greater than or equal to the acceleration amount upper limit Gmax (S205). This acceleration amount upper limit Gmax is, for example, a configurable value that is tested in the test operation.

[0029] If the backlash acceleration amount G has not reached the upper limit of the acceleration amount Gmax (S205: NO), the setting is changed to increase the backlash acceleration amount Gn for that run by a predetermined increase amount g (S206). Here, the backlash acceleration amount Gn refers to the backlash acceleration amount G for any number of times n in which the test operation is performed. Therefore, the test operation is performed again using the new backlash acceleration amount G value increased by the increase amount g (S203), and the position deviation calculated in the same way is stored along with the values ​​of the backlash acceleration amount G and the backlash acceleration time T (S204). Note that in the first adjustment stage in which the value of the backlash acceleration amount G is changed, the backlash acceleration time T remains fixed at its initial value.

[0030] In the first adjustment stage, if the backlash acceleration amount G does not reach the upper limit of acceleration amount Gmax (S205: NO), the process from step S203 to step S206 is repeated. On the other hand, if the backlash acceleration amount G reaches the upper limit of acceleration amount Gmax (S205: YES), the process moves to the second adjustment stage, where the setting of the backlash acceleration amount G is returned to the initial value at the time of the test operation n=1 (S207), and the backlash acceleration time T is checked (S208). If the backlash acceleration time T is less than the upper limit of acceleration time Tmax (S207: NO), the backlash acceleration time Tn is increased by an increase amount t (S209). Here again, the backlash acceleration time Tn refers to the backlash acceleration time T at any number of times n the test operation is performed.

[0031] Then, the process returns to step S203 with a new backlash acceleration time T set by the increased amount t, and the subsequent steps are repeated. That is, the process from step S203 to step S206 is repeated as described above until the backlash acceleration amount G reaches the upper limit of the acceleration amount Gmax, based on the new value of the backlash acceleration time T. After that, if the backlash acceleration amount G reaches the upper limit of the acceleration amount Gmax (S205: YES), the backlash acceleration amount G is returned to its initial value (S207), and it is checked whether the backlash acceleration time T has reached the upper limit of the acceleration time Tmax (S208).

[0032] However, if the backlash acceleration time T has not reached the upper limit of the acceleration time Tmax (S208: NO), the value of the backlash acceleration time Tn is increased (S209), and the process from step S203 to step S207 is repeated. Then, if the backlash acceleration time T reaches the upper limit of the acceleration time Tmax (S208: YES), in step S204, the backlash acceleration amount G and backlash acceleration time T that represent the minimum position deviation are read out from the data stored for each step. The backlash acceleration amount G and backlash acceleration time T are set as adjustment parameters to be used for machining (S210), and the quadrant switching parameter adjustment process is completed. In this embodiment, both the backlash acceleration amount G and the backlash acceleration time T are adjusted, but it is also possible to adjust only one of them.

[0033] Next, the program returns to the main program, the stirring program, shown in Figure 5, and it is checked whether the torque when the linear reciprocating movement by the Z-axis servo motor 41 is smaller than a predetermined reference value (S105). At this point, the sliding member has repeatedly moved within the range of the track K1 during the parameter adjustment process, and the accumulated lubricating oil has been spread widely on the guide rail 13, etc. However, if the number of test operations n mentioned above was small, this may not be sufficient, and if the torque detected by the Z-axis servo motor 41 is greater than or equal to the reference value (S105: NO), an additional 20 reciprocating movements are performed only in the Z-axis direction within the range of the track K1 (S106).

[0034] Subsequently, the torque detected by the Z-axis servo motor 41 is compared again with the reference value (S107). If the torque of the Z-axis servo motor 41 is still above the reference value (S107:NO), some kind of malfunction is suspected, and an alarm display and alarm sound are emitted on the operation display device 6 to notify the operator (S108), and the stirring process program is terminated.

[0035] On the other hand, if the torque of the Z-axis servo motor 41 is less than the reference value due to the parameter adjustment process spreading the lubricating oil more widely (S105:YES), or if the torque of the Z-axis servo motor 41 becomes less than the reference value due to additional reciprocating movement (S106) (S107:YES), the processing flag "1" corresponding to the Z-axis is set (S109). Then, the flag is used to confirm whether the stirring operation has been completed for all axes (S110).

[0036] In machine tool 1, the Z-axis and X-axis are the targets, and after the processing of the Z-axis is completed, the processing flag for the X-axis is confirmed to be "0" (S110: NO). Therefore, in order to perform processing on the X-axis next, the process returns to step S101, and the same processing as for the Z-axis described above is performed on the X-axis. That is, for the trajectory K2 including the arc-shaped portion K2a in the X-axis direction shown in Figure 3, a lubricating oil stirring operation including parameter adjustment processing is performed. Through this processing, in addition to parameter adjustment, the lubricating oil is diffused on the X-axis as well, and if the torque of the X-axis servo motor 42 becomes smaller than the reference value (S105: YES or S107: YES), the processing flag corresponding to the X-axis is set to "1" (S109).

[0037] Then, if the completion of the stirring operation for all axes is confirmed by the processing flag (S110:YES), the stirring processing program is terminated. On the other hand, if the torque of the X-axis servo motor 42 is above the reference value (S105:NO or S107:NO), an alarm display or alarm sound is emitted on the operation display device 6 (S108), and the stirring processing program is terminated. The processing flags for the Z-axis and X-axis are set to "0", for example, when the power is turned off.

[0038] According to the machine tool 1 of this embodiment, the tool post 12 is repeatedly moved back and forth over the maximum possible range in the Z-axis and X-axis directions by the stirring process program, thereby diffusing the lubricating oil accumulated on the guide rails 13, 15, etc. Furthermore, since a parameter adjustment process program is incorporated as a subroutine within the stirring process program, it is also possible to simultaneously adjust the backlash acceleration amount and backlash acceleration time in the X-axis and Z-axis directions. In other words, it is possible to find parameters that result in less deviation from the commanded movement position, making it possible to reduce or eliminate the quadrant protrusions 35. Moreover, since this is executed within the stirring process program, the workload of the operator in adjusting the parameters is reduced. In addition, since the stirring process program also includes a torque confirmation process for the Z-axis servo motor 41 and the X-axis servo motor 42, it is possible to check the status of the linear drive unit 40 on the guide rails 13, 15, etc.

[0039] Incidentally, as mentioned earlier, lubricating oil can accumulate due to reciprocating movement within the same range, but in a more severe case, abnormal wear may occur. This is because machine tools sometimes produce large quantities of the same workpiece. In such cases, abnormal wear may occur in the linear drive unit 40, particularly on the guide rails 13 and 15, and in subsequent machining operations for a new workpiece with different machining requirements, this can cause machining inaccuracies such as steps on the machined surface.

[0040] Abnormal wear can occur due to reciprocating movement within a limited, narrow range. Therefore, to address such problems, it is preferable to periodically reciprocate the tool post 12 across the maximum possible range of movement without biasing the movement range. In the above embodiment, the case where this is performed when the power is turned on was described, but since the occurrence of abnormal wear depends on the machining content, various judgment criteria should be set, and since they differ between the Z axis and the X axis, it is preferable to set judgment criteria for each axis.

[0041] As a criterion for this determination, for example, to check whether the guide rails 13 and 15 are being used over a wide area, an arbitrary point position is set, and a determination is made as to whether the machine has passed through that position within a certain time. If there is no record of the machine passing through that point, the machine is made to perform 20 back-and-forth movements in the corresponding axial direction, as shown in step S106 in Figure 5 above. At this time, it is preferable to display an alarm on the operation display device 6 to notify the operator that the movement range of the slide member is biased.

[0042] Although one embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications are possible without departing from its spirit. Furthermore, the machine tool is not limited to a lathe as in the above embodiment; various types of machine tools can be used, such as machining centers, milling machines, and drilling machines. Furthermore, while machine tool 1 uses the Z-axis and X-axis as drive axes, it may also be a machine tool with a structure that includes a third drive axis. [Explanation of symbols]

[0043] 1...Machine tool 3...Spindle unit 4...Turret unit 5...Control device 11...Spindle chuck 12...Tool post 13,15...Guide rails 18...Tool 40...Linear drive unit 41...Z-axis servo motor 42...X-axis servo motor

Claims

1. Multiple linear drive units that move a tool post equipped with a tool in a predetermined axial direction, The system includes a control device that controls the movement of the tool by a combination of linear movements in each axial direction of the linear drive unit, The control device is A main process in which, at a predetermined timing, the linear drive unit in each axial direction reciprocates the tool post within a predetermined range for each axis, During the main processing in the axial direction of one of the multiple linear drive units, a sub-process adjusts the quadrant switching parameter that reverses the movement direction of the other linear drive units. A machine tool that performs this task.

2. The machine tool according to claim 1, wherein the predetermined range in which the control device reciprocates the tool post during the main process exceeds the area where lubricating oil accumulates in the linear drive unit.

3. The aforementioned subprocessing is, A test operation is performed in which at least one of the parameters of backlash acceleration amount and backlash acceleration time, which are parameters used when switching quadrants to reverse the direction of movement in the other linear drive unit, is changed. The positional deviation between the commanded movement position and the actual movement position in the movement command for the tool rest is acquired for each of the multiple test operations, and the parameter for the test operation corresponding to the smallest positional deviation is adjusted to the correct value. A machine tool according to claim 1 or claim 2, which performs the following:

4. The machine tool according to claim 1 or 2, wherein the main process, after completing the sub-process, performs a reciprocating movement by a servo motor constituting the corresponding linear drive unit, and compares the torque at that time with a predetermined reference value.

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