Machine tool control device and machine tool control program

Abstract

The purpose of the present invention is to achieve both breaking of cuttings and suppression of mechanical resonance. A machine tool control device generates gas cutting during cutting of a workpiece by superimposing a swing command for commanding relative swing of the workpiece and a cutting tool on a movement command for commanding relative movement of the workpiece and the cutting tool, thereby breaking chips. A position information acquisition unit of a machine tool control device acquires position information relating to the relative position of a workpiece and a tool. A state determination unit of the machine tool control device determines an unstable state on the condition that a position deviation exceeds a threshold value, the position deviation being greater as a difference between an actual relative position as a relative position based on the position information and a command relative position as a relative position based on the movement command and the swing command is greater. A swing switching unit of the machine tool control device performs a switching process for switching a swing condition of the relative swing on the condition that the state is determined to be unstable.

Description

Technical Field

[0001] The invention relates to a machine tool control device for controlling a machine tool. Background Art

[0002] In a machine tool control device, by superimposing a swing command for instructing relative swing of the workpiece and the cutting tool on a movement command for instructing relative movement of the workpiece and the cutting tool, gas cutting is generated during cutting of the workpiece by the cutting tool to separate chips.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-144588 Summary of the invention

[0006] Problems to be solved by the invention

[0007] According to such a machine tool control device, the chips are finely divided by relative swinging, and the disadvantages such as the chips being entangled with the cutting tool can be suppressed. However, the present inventors have focused on the fact that the following problems may occur.

[0008] That is, depending on the swing conditions, mechanical resonance may be induced due to the frequency of the relative swing coinciding with the resonance frequency for the machine tool, etc. As a result, it may cause poor processing of the workpiece, stoppage of the machine tool, damage to the cutting tool, etc. On the other hand, as for confirming in advance that mechanical resonance is not induced, since the swing conditions may vary depending on the processing conditions, it is necessary to comprehensively perform it for each processing condition, which is relatively difficult.

[0009] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to achieve both chip breaking and suppression of mechanical resonance.

[0010] Means for solving problems

[0011] The machine tool control device disclosed in the present invention, in the control of a machine tool having a cutting tool for cutting a workpiece, superimposes a swing instruction for instructing the relative swing of the workpiece and the cutting tool on a movement instruction for instructing the relative movement of the workpiece and the cutting tool, thereby generating gas cutting during the cutting of the workpiece to break the chips,

[0012] The machine tool control device has:

[0013] a position information acquisition unit that acquires position information related to the relative position of the workpiece and the cutting tool;

[0014] a state determination unit that determines that the state is unstable if the larger the difference between the actual relative position as the relative position based on the position information and the command relative position as the relative position based on the movement command and the swing command, the larger the position deviation exceeds a threshold value; and

[0015] The swing switching unit performs a switching process for switching the swing condition of the relative swing, on the condition that the unstable state is determined.

[0016] The machine tool control program disclosed in the present invention enables a computer to function as a machine tool control device, which, in controlling a machine tool having a cutting tool for cutting a workpiece, superimposes a swing instruction for instructing the relative swing of the workpiece and the cutting tool on a movement instruction for instructing the relative movement of the workpiece and the cutting tool, thereby generating gas cutting during the cutting of the workpiece to break chips.

[0017] The machine tool control program also enables the computer to function as:

[0018] a position information acquisition unit that acquires position information related to the relative position of the workpiece and the cutting tool;

[0019] a state determination unit that determines that the state is unstable if the larger the difference between the actual relative position as the relative position based on the position information and the command relative position as the relative position based on the movement command and the swing command, the larger the position deviation exceeds a threshold value; and

[0020] The swing switching unit performs a switching process for switching the swing condition of the relative swing, on the condition that the unstable state is determined.

[0021] Effects of the Invention

[0022] According to the present disclosure, it is possible to achieve both chip breaking and suppression of mechanical resonance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a block diagram showing a machine tool control device and a machine tool according to the first embodiment.

[0024] Figure 2 This is a diagram showing the structure of a machine tool control device.

[0025] Figure 3 It is a graph showing the actual relative position and the transition of the position deviation.

[0026] Figure 4 It is a block diagram showing a machine tool control device according to a second embodiment.

[0027] Figure 5 It is a graph showing the transition of position deviation.

[0028] Figure 6 It is a block diagram showing a machine tool control device according to a third embodiment. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments at all, and can be implemented with appropriate changes within the scope of the present disclosure.

[0030] [First embodiment]

[0031] like Figure 1 As shown, the machine tool 80 includes a workpiece holding portion 85 for holding a workpiece 86 and a tool holding portion 87 for holding a cutting tool 88. The workpiece holding portion 85 is driven by, for example, a first motor 81a as a spindle motor, and the tool holding portion 87 is driven by, for example, a second motor 81b and a third motor 81c. Hereinafter, each of the first motor 81a, the second motor 81b, and the third motor 81c is simply referred to as a "motor 81".

[0032] The workpiece 86 and the cutting tool 88 move relative to each other through the relative movement of the workpiece holding portion 85 and the tool holding portion 87. Hereinafter, the relative movement of the cutting tool 88 and the workpiece 86 for cutting the workpiece 86 will be referred to as "relative movement", and the relative position of the cutting tool 88 and the workpiece 86 will be referred to as "relative position". In addition, the relative swing of the cutting tool 88 and the workpiece 86 in a direction intersecting the direction of the relative movement will be referred to as "relative swing".

[0033] Each motor 81 is provided with an encoder 82 for detecting the rotation angle of the motor 81. Hereinafter, the relative position based on the rotation angle detected by the encoder 82 is referred to as an "actual relative position Pa".

[0034] The machine tool control device 50 controls the machine tool 80 shown above. The machine tool control device 50 is mainly composed of, for example, a numerical control device and a servo control device that operates the motor 81 and the like according to the instructions from the numerical control device. In addition, from another point of view, the machine tool control device 50 is mainly composed of a computer Cp and a machine tool control program Pg for making it function as the machine tool control device 50. The computer Cp mentioned here includes a numerical control device and a servo control device, etc., and has a computing unit, a display, an operating unit, etc. The computing unit of the computer Cp has, for example, a CPU, a RAM, a ROM, etc.

[0035] The machine tool control device 50 makes the cutting tool 88 contact the workpiece 86 through relative movement based on the control of the machine tool 80, and further moves relative to each other from this state, thereby cutting the workpiece 86 with the cutting tool 88. In addition, during the cutting of the workpiece 86, the machine tool control device 50 superimposes the relative swing and the relative movement, intermittently generates gas cutting in which the cutting tool 88 does not cut the workpiece 86 but runs idle, thereby breaking the chips.

[0036] like Figure 2 As shown, the machine tool control device 50 includes a machining command unit 11, a movement command unit 18, a swing command unit 28, an adder 21, a subtractor 22, a position / speed control unit 35, and a current control unit 36. The subtractor 22 may be replaced by a "position information acquisition unit".

[0037] The machining instruction unit 11 is configured so that a machining program can be input by a user, for example, by operating an operation unit while checking a display of a numerical controller or the like.

[0038] The movement command unit 18 calculates a "movement command C1" as a command value for relative movement based on a machining command Cx based on a machining program. The swing command unit 28 calculates a "swing command C2" as a command value for relative swing based on a machining condition X based on a machining program. Specifically, the swing command unit 28 calculates a sinusoidal wave command with repeatability as the swing command C2.

[0039] The adder 21 obtains the movement command C1 from the movement command unit 18 and the swing command C2 from the swing command unit 28. Then, the superimposition command C3 is calculated by adding the swing command C2 to the movement command C1. Hereinafter, the relative position in the case of relative movement according to the superimposition command C3 is referred to as the "command relative position Pc".

[0040] The subtractor 22 obtains the command relative position Pc from the adder 21 and obtains the actual relative position Pa from the encoder 82. Then, the position deviation ΔP is calculated by subtracting the actual relative position Pa from the command relative position Pc.

[0041] The position / speed control unit 35 obtains the position deviation ΔP from the subtractor 22 . Then, based on the position deviation ΔP or its integrated value, the position / speed control unit 35 generates a torque command for the motor 81 . That is, the position / speed control unit 35 performs feedback control in cooperation with the subtractor 22 .

[0042] The current control unit 36 ​​calculates a current value based on the torque command received from the position / speed control unit 35, and operates the motor 81 based on the current value. Thus, the cutting tool 88 cuts the workpiece 86, and gas cutting is performed to break the chips.

[0043] Next, refer to Figure 3 , the issues to be solved in this embodiment are explained. Figure 3 The upper curve represents an example of the transition of the actual relative position Pa. That is, the upper curve is blackened due to close contact in the lateral direction, but forms a wavy trajectory including relative swing. The dotted line overlapping with the curve representing the actual relative position Pa represents the command relative position Pc. The amplitude of the command relative position Pc is smaller than the amplitude of the actual relative position Pa during most of the periods t1 and t2 described later. The lower curve represents the transition of the position deviation ΔP. Regarding this position deviation ΔP, it is also blackened due to close contact in the lateral direction, but forms a wavy trajectory with approximately the same period as the actual relative position Pa. In addition, in this Figure 3 In the figure, the position deviation ΔP is magnified in the vertical direction. Figure 3 The length of “ΔP” in the longitudinal direction is longer than the difference between “Pc” and “Pa” in the longitudinal direction.

[0044] Hereinafter, the period during which relative movement and relative swing are performed in a predetermined manner is referred to as the "first period t1", and the period during which relative movement and relative swing are performed in a different manner is referred to as the "second period t2". In the first period t1, mechanical resonance is not generated much, so the position deviation ΔP converges to a relatively small value. In contrast, in the second period t2, mechanical resonance is generated largely, so the position deviation ΔP becomes larger than that in the first period t1. As a result, poor processing of the workpiece 86, stopping of the machine tool 80, damage to the cutting tool 88, etc. may occur.

[0045] In order to solve the above problems, Figure 2 As shown, the machine tool control device 50 further includes a threshold setting unit 24 , a state determination unit 25 , and a swing switching unit 26 .

[0046] The threshold setting unit 24 obtains the swing command C2 from the swing command unit 28 to calculate the "command amplitude" as the amplitude of the command relative position Pc, and sets a value larger than the command amplitude as the threshold ΔPth of the position deviation ΔP. Specifically, for example, the larger the command amplitude is, the larger the threshold ΔPth is set by the threshold setting unit 24. More specifically, the threshold setting unit 24 sets the threshold ΔPth as, for example, a value obtained by multiplying the command amplitude by a prescribed value, or a value obtained by further adding or subtracting a prescribed value from the command amplitude. However, instead of this, the threshold ΔPth may be set larger in stages as the command amplitude increases. That is, in addition to calculating the threshold ΔPth by multiplying the command amplitude by a fixed value, the threshold ΔPth may also be calculated by changing the prescribed value of the multiplication according to the size of the command amplitude. The threshold setting unit 24 sends the set threshold ΔPth to the state determination unit 25.

[0047] The state determination unit 25 obtains the position deviation ΔP from the subtractor 22 and the threshold ΔPth from the threshold setting unit 24. When the position deviation ΔP is less than the threshold ΔPth, the state is determined to be a stable state, and when the position deviation ΔP exceeds the threshold ΔPth, the state is determined to be an unstable state. That is, the state determination unit 25 determines that the state is an unstable state on the condition that the position deviation ΔP exceeds the threshold ΔPth. The state determination unit 25 sends the determination result J to the swing switching unit 26.

[0048] The swing switching unit 26 sends a switching command Cs to the swing command unit 28 on the condition that the determination result J is an unstable state. The process of sending the switching command Cs corresponds to a "switching process" which is a process for switching the swing condition.

[0049] Hereinafter, the vibration frequency of the command relative position Pc is referred to as the "command frequency". The swing switching unit 26 sends at least one of a command to change the command frequency and a command to reduce the command amplitude as a switching command Cs to the swing command unit 28. The swing command unit 28 switches the swing condition of the relative swing according to the switching command Cs.

[0050] If the stable state is not achieved even after the switching, the state determination unit 25 determines that the state is unstable again, and the swing switching unit 26 issues a switching command Cs again to switch the swing condition again. Therefore, the swing condition is repeatedly switched until the stable state is achieved, that is, the amplitude of the position deviation ΔP converges to or below the threshold ΔPth. Thus, the stable state is finally achieved.

[0051] The structure and effects of this embodiment are summarized below.

[0052] The adder 21 generates a superimposed instruction C3 in which the swing instruction C2 is superimposed on the movement instruction C1. Based on the superimposed instruction C3, the position / speed control unit 35 and the current control unit 36 ​​control the motor 81, thereby cutting the workpiece 86 and generating gas cutting. As a result, the workpiece 86 can be cut and the chips generated thereby can be broken, thereby preventing the chips from being entangled in the cutting tool 88 and other disadvantages.

[0053] The subtractor 22 obtains the command relative position Pc from the adder 21 and obtains the actual relative position Pa from the encoder 82 to calculate the position deviation ΔP. The state determination unit 25 determines that the state is unstable when the position deviation ΔP exceeds the threshold ΔPth. The swing switching unit 26 switches the swing condition of the relative swing when the state is determined to be unstable. In this way, the unstable state can be avoided and the mechanical resonance can be suppressed.

[0054] As described above, according to the present embodiment, it is possible to realize both chip breaking and mechanical resonance suppression. More specifically, the following effects are further obtained.

[0055] When the swing switching unit 26 determines that the state is unstable, it performs at least one of the process of changing the command frequency and the process of reducing the command amplitude as a switching process. When the command frequency is changed, the frequency of the relative swing is shifted from the resonance frequency for the machine tool 80, and mechanical resonance can be avoided. In addition, when the command amplitude is reduced, the amplitude of the relative swing can be suppressed and the mechanical resonance can be suppressed to a small level. Therefore, the mechanical resonance can be suppressed.

[0056] The threshold setting unit 24 calculates the threshold ΔPth according to the magnitude of the command amplitude. Specifically, the threshold setting unit 24 sets a value greater than the command amplitude calculated by the swing command unit 28 as the threshold ΔPth each time, thereby being able to set the threshold ΔPth of an appropriate magnitude.

[0057] [Second embodiment]

[0058] Next, refer to Figure 4 , Figure 5 The second embodiment will be described. This embodiment is based on the first embodiment, and the description will be mainly focused on the points different therefrom, and the description of the same or similar points as the first embodiment will be appropriately omitted.

[0059] like Figure 4 As shown, the machine tool control device 50 of this embodiment further includes a deviation storage unit 23. The deviation storage unit 23 obtains and stores the position deviation ΔP from the subtractor 22. The threshold setting unit 24 calculates the threshold ΔPth based on the position deviation history ΔPd stored in the deviation storage unit 23. Specifically, it is as follows.

[0060] The following, such as Figure 5 As shown, the swing period of the position deviation ΔP is called "deviation swing period ωΔ", and the swing period of the command relative position Pc is called "command swing period ωc". As described above, the adder 21 superimposes the repetitive sinusoidal wave command as the swing command C2 on the movement command C1. Therefore, the position deviation ΔP contains interference, such as cutting interference, and on the other hand, contains more frequency components that are the same as the sinusoidal wave command. That is, the command swing period ωc and the deviation swing period ωΔ are substantially equal. Hereinafter, the command swing period ωc and the deviation swing period ωΔ are collectively referred to as "swing period ω". In addition, hereinafter, the interval divided according to the swing period ω is referred to as "divided interval Sc", and the maximum value of the position deviation ΔP in the divided interval Sc is referred to as "maximum deviation ΔPmax within the interval". However, instead of the maximum value of the position deviation ΔP, the maximum value of the absolute value of the position deviation ΔP can also be set to "maximum deviation ΔPmax within the interval".

[0061] The threshold setting unit 24 calculates the maximum deviation ΔPmax within each segmented interval Sc. Specifically, in the present embodiment, the length of each segmented interval Sc is an integer multiple of the length of half the swing period ω. Therefore, the maximum value of the position deviation ΔP in each segmented interval Sc becomes the maximum deviation ΔPmax within the segmented interval Sc. The state in which the maximum deviation ΔPmax within the segment becomes the minimum value ΔPmax_min can be regarded as the steady state of the position deviation ΔP, that is, the stable state.

[0062] The threshold setting unit 24 sets the threshold ΔPth as a value obtained by multiplying the minimum value ΔPmax_min of the intra-section maximum deviation by a predetermined factor greater than 1. However, instead, a value obtained by multiplying the average value of the intra-section maximum deviation ΔPmax in a plurality of predetermined divided sections Sc by a predetermined factor greater than 1 may be set as the threshold ΔPth.

[0063] like Figure 4 As shown, the threshold setting unit 24 sends the set threshold ΔPth to the state determination unit 25. The following operations are the same as those in the first embodiment. Therefore, the state determination unit 25 performs state determination based on the received threshold ΔPth.

[0064] The structure and effects of this embodiment are summarized below.

[0065] The deviation storage unit 23 stores the position deviation ΔP. The threshold setting unit 24 calculates the threshold ΔPth based on the history ΔPd of the position deviation ΔP stored in the deviation storage unit 23. Thus, the threshold ΔPth can be set based on the position deviation ΔP up to now instead of setting the threshold ΔPth based on the command amplitude alone. Thus, a more appropriate setting of the threshold ΔPth can be expected.

[0066] The threshold setting unit 24 calculates the maximum deviation ΔPmax within each segmented segment Sc. The maximum deviation ΔPmax within the segment is calculated sequentially, and the calculated maximum deviation ΔPmax within the segment is compared with the stored maximum deviation ΔPmax within the segment, and the smaller maximum deviation ΔPmax within the segment is always updated as the minimum value ΔPmax_min. The minimum value ΔPmax_min can be regarded as the steady state, that is, the stable state, of the position deviation ΔP. The threshold ΔPth is determined based on the minimum value ΔPmax_min, so a more appropriate setting of the threshold ΔPth can be expected.

[0067] The adder 21 superimposes the repetitive sine wave command as the swing command C2 on the movement command C1. Therefore, the position deviation ΔP also contains many frequency components that are the same as the sine wave. In view of this feature, the period of the divided interval Sc is set to an integral multiple of the period of half the command swing period ωc. The maximum deviation in the divided interval Sc is used as the maximum deviation ΔPmax in the interval to set the threshold ΔPth, thereby setting a more appropriate threshold ΔPth.

[0068] The threshold setting unit 24 sets the value obtained by multiplying the minimum value ΔPmax_min of the intra-section maximum deviation or the average value of the intra-section maximum deviation ΔPmax in the plurality of divided sections Sc by a predetermined factor greater than 1 as the threshold ΔPth. Thus, a margin can be provided between the minimum value ΔPmax_min and the threshold ΔPth, or between the average value and the threshold ΔPth. Therefore, it is possible to suppress the disadvantage that the position deviation ΔP is determined to be in an unstable state every time it exceeds the threshold ΔPth due to disturbance or the like.

[0069] [Third Embodiment]

[0070] Next, refer to Figure 6 The third embodiment will be described. This embodiment is based on the second embodiment, and the description will be mainly focused on the points different therefrom, and the description of the same or similar points as the second embodiment will be appropriately omitted.

[0071] The machine tool control device 50 also includes a learning unit 33 and a second adder 21b. The learning unit 33 calculates a correction amount α according to the position deviation ΔP, and adds the calculated correction amount α to the position deviation ΔP through the second adder 21b, thereby reducing the position deviation ΔP. The learning unit 33 includes a memory, and stores the swing phase and the position deviation ΔP in association with each other in one or more cycles of the swing. In addition, the correction amount α calculated based on the position deviation ΔP stored in the memory is output to the second adder 21b at a timing that can compensate for the phase delay of the swing action corresponding to the responsiveness of the motor 81. Generally speaking, the higher the swing frequency, the larger the position deviation ΔP relative to the command amplitude. Therefore, by performing the correction of the learning unit 33, the tracking performance of the actual relative swing relative to the periodic swing command C2 can be improved. As a result, the tracking performance of the actual relative position Pa relative to the command relative position Pc is also improved, and the position deviation ΔP is reduced. Furthermore, the machining accuracy can be improved.

[0072] As described above, the learning unit 33 calculates the correction amount α based on the position deviation ΔP, and corrects the position deviation ΔP by adding the calculated correction amount α to the position deviation ΔP. As a result, the position deviation ΔP is reduced. The swing condition is changed on the condition that the position deviation ΔP exceeds the threshold ΔPth. Therefore, it is expected to suppress the frequency of changes in the swing condition and further suppress mechanical resonance.

[0073] [Other embodiments]

[0074] The above-described embodiment can be modified as follows, for example. As a switching process, the swing switching unit 26 can also perform a process of notifying the user of the need to switch the swing condition through at least one of a display and a sound instead of performing the process of switching the swing condition. Specifically, for example, as a switching process, a method of causing a display to perform the display can be cited. In addition, for example, the swing switching unit 26 has a speaker, and as a switching process, a method of causing the speaker to sound the sound can also be cited.

[0075] 22 Subtractor (position information acquisition unit)

[0076] 23 Deviation storage unit

[0077] 24 Threshold setting unit

[0078] 25 Status determination unit

[0079] 26 Swing switch

[0080] 33 Learning Department

[0081] 50 Machine tool control device

[0082] 80 Machine Tools

[0083] 86 Workpieces

[0084] 88 Cutting tools

[0085] C1 Move Command

[0086] C2 Swing command

[0087] C3 Overlay Command

[0088] Cp Computer

[0089] Pa Actual relative position

[0090] Pc command relative position

[0091] Pg Machine tool control program

[0092] ΔP Position deviation

[0093] ΔPth threshold

[0094] ΔPmax Maximum deviation within the interval

[0095] Minimum value of the maximum deviation within the ΔPmax_min interval

[0096] ω oscillation period.

Claims

1. A machine tool control device, in the control of a machine tool having a cutting tool for cutting a workpiece, superimposing a swing instruction for instructing the relative swing of the workpiece and the cutting tool on a movement instruction for instructing the relative movement of the workpiece and the cutting tool, thereby generating gas cutting during the cutting of the workpiece to break the chips, characterized in that: The machine tool control device has: a position information acquisition unit that acquires position information related to the relative position of the workpiece and the cutting tool; a state determination unit for determining an unstable state on the condition that a larger position deviation exceeds a threshold value as a difference between an actual relative position as the relative position based on the position information and a command relative position as the relative position based on the movement command and the swing command increases; as well as The swing switching unit performs a switching process for switching the swing condition of the relative swing, on the condition that the unstable state is determined.

2. The machine tool control device according to claim 1, characterized in that: The swing switching unit performs, as the switching process, at least one of a process of changing the frequency of the relative swing and a process of reducing the amplitude of the relative swing based on the swing command.

3. The machine tool control device according to claim 1, characterized in that: As the switching process, the swing switching unit performs a process of notifying a user through at least one of a display and a sound that the swing condition needs to be switched.

4. The machine tool control device according to any one of claims 1 to 3, characterized in that: The machine tool control device includes a threshold setting unit that sets a value larger than an amplitude of the relative swing based on the swing command as the threshold.

5. The machine tool control device according to any one of claims 1 to 3, characterized in that: The machine tool control device includes: a deviation storage unit that stores the position deviation; and a threshold setting unit that sets the threshold based on a history of the position deviation stored in the deviation storage unit.

6. The machine tool control device according to claim 5, characterized in that: The threshold setting unit calculates a maximum deviation within the interval as a maximum value of the position deviation or a maximum value of an absolute value of the position deviation for each divided interval divided according to the swing period as the period of the relative swing, and determines the threshold according to the maximum deviation within the interval.

7. The machine tool control device according to claim 6, characterized in that: The length of each of the divided intervals is an integral multiple of half the length of the oscillation period.

8. The machine tool control device according to claim 6 or 7, characterized in that: The threshold setting unit sets as the threshold a value obtained by multiplying the maximum deviation within the divided interval in which the maximum deviation within the interval is the smallest or an average value of the maximum deviation within the interval among a plurality of the divided intervals by a predetermined magnification greater than 1.

9. The machine tool control device according to any one of claims 1 to 8, characterized in that: The machine tool control device includes a learning unit that calculates a correction amount of the position deviation based on the position deviation, and corrects the position deviation by adding the calculated correction amount to the position deviation.

10. A machine tool control program, which enables a computer to function as a machine tool control device, wherein the machine tool control device, in controlling a machine tool having a cutting tool for cutting a workpiece, superimposes a swing instruction for instructing the relative swing of the workpiece and the cutting tool on a movement instruction for instructing the relative movement of the workpiece and the cutting tool, thereby generating gas cutting during the cutting of the workpiece to break chips, characterized in that: The machine tool control program also enables the computer to function as: a position information acquisition unit that acquires position information related to the relative position of the workpiece and the cutting tool; a state determination unit for determining an unstable state on the condition that a larger position deviation exceeds a threshold value as a difference between an actual relative position as the relative position based on the position information and a command relative position as the relative position based on the movement command and the swing command increases; as well as The swing switching unit performs a switching process for switching the swing condition of the relative swing, on the condition that the unstable state is determined.

Images