NUMERICAL CONTROL DEVICE, PROGRAM AND CONTROL METHOD

Abstract

A numerical control device (I) for controlling a machine tool, comprising: at least one spindle (Ac) which causes a cutting tool (T) and a workpiece (W) to rotate relative to each other, and at least one feed axis (Az) which causes the cutting tool (T) to move relative to the workpiece (W), and which cuts the workpiece (W) by means of the cutting tool (T) by causing the spindle (Ac) and the feed axis (Az) to cooperate, the numerical control device (I) comprising: an upper limit value detecting unit (13) that detects an upper limit value for a cutting speed, which is a relative speed of the cutting tool (T) to the workpiece (W); a reference speed calculation unit (14) that calculates a rotational speed of the spindle (Ac) and a feed speed, which is a moving speed of the feed axis (Az); an oscillation speed calculation unit (15) that calculates an oscillation speed superimposed on the feed speed; a cutting speed calculation unit (16) which calculates the cutting speed based on the spindle speed (Ac), the feed rate and the oscillation speed; and a speed setting unit (17) which sets the speed of the spindle (Ac) and / or the feed rate so that a maximum value of the cutting speed calculated by the cutting speed calculation unit (16) does not exceed the upper limit value detected by the upper limit value detection unit (13).

Description

BACKGROUND OF THE INVENTIONSubject of the invention

[0001] The present invention relates to a numerical control apparatus, a program and a control method. State of the art

[0002] From the prior art, a machine tool is known, such as a lathe, which comprises a spindle which causes a relative movement of a cutting tool and a workpiece, and a feed axis which causes a movement of the cutting tool relative to the workpiece and cuts the workpiece with the aid of the cutting tool by means of the spindle and the feed axis interacting.

[0003] Furthermore, in a machine tool such as a lathe, since the cutting edge of the tool continuously cuts away material on a surface of the workpiece, the cut material takes the form of long, thin chips (chips) depending on the material properties of the workpiece, and there is a possibility that these chips will prevent machining of the workpiece by adhering to the cutting tool. In contrast, a technology that performs oscillating cutting by reciprocating the cutting tool relative to the workpiece at a predetermined oscillation frequency is known, for example, from Patent Document 1. Since the cutting tool is periodically separated from the workpiece due to the reciprocating movement of the cutting tool, the chips are reduced to a specific length during oscillating cutting.

[0004] Patent Document 1: Unexamined Japanese Patent Application, Publication No. JP 2018 - 94 690 A.

[0005] DE 11 2014 006 864 T5 discloses a numerical control device that moves a tool and an object to be machined relative to each other along a travel path using a drive shaft associated with the tool or the object to be machined and simultaneously oscillates the tool or the object to be machined so that the object to be machined is machined, the numerical control device comprising: an analysis processing unit for reading a feed rate and a clamping speed when moving along the travel path from a machining program, a post-oscillation superimposed speed calculation unit for calculating a post-oscillation superimposed speed obtained by superimposing the oscillation on a movement with the feed rate based on a given oscillation cutting condition,and an oscillation speed clamping unit for reducing the feed speed to be less than or equal to the clamping speed when the post-oscillation superposition speed exceeds the clamping speed. SUMMARY OF THE INVENTION

[0006] When performing oscillating cutting, in which the cutting tool is reciprocated in the aforementioned manner, the cutting speed, which is the relative speed of the cutting tool and a workpiece surface, continuously increases because the feed rate of the cutting tool changes periodically. Generally, the cutting speed range within which suitable cutting is possible is limited depending on the cutting tool and the material properties of the workpiece, etc. If the cutting speed becomes too high, various problems may occur, such as roughness on the machined workpiece surface due to the generation of vibrations due to chatter, excessive load or fatigue of the machine tool drive mechanism, and abnormal wear of the cutting tool.For this reason, in the case of performing oscillating cutting on a conventional machine tool, it is necessary to set the spindle speed and the tool feed rate so low that the cutting speed of the cutting tool does not become too high, taking into account the speed fluctuations of the cutting tool.

[0007] Therefore, it is an object of the present invention to provide a numerical control apparatus, a program and a control method that can prevent the cutting speed of a cutting tool from becoming too high when performing oscillating cutting.

[0008] The problem is solved by a numerical control device having the features of patent claim 1, by a program having the features of patent claim 4 and by a control method having the features of patent claim 5.

[0009] A numerical control device (the numerical control device 1 described later) according to the present invention is a numerical control device for controlling a machine tool (the machine tool 100 described later), comprising: at least one spindle (the spindle Ac described later) that causes a cutting tool (the cutting tool T described later) and a workpiece (the workpiece W described later) to rotate relative to each other, and at least one feed axis (the feed axis Az described later) that causes the cutting tool to move relative to the workpiece and cuts the workpiece with the cutting tool by causing the spindle and the feed axis to cooperate, the numerical control device comprising: an upper limit value detecting unit (the upper limit value detecting unit 13 described later),which detects an upper limit value for a cutting speed, which is a relative speed of the cutting tool to the workpiece; a reference speed calculation unit (the reference speed calculation unit 14 described later) that calculates a rotational speed of the spindle and a feed rate, which is a moving speed of the feed axis; an oscillation speed calculation unit (the oscillation speed calculation unit 15 described later) that calculates an oscillation speed superimposed on the feed rate; a cutting speed calculation unit (the cutting speed calculation unit 16 described later) that calculates the cutting speed based on the rotational speed of the spindle, the feed rate, and the oscillation speed; and a speed setting unit (the speed setting unit 17 described later).which adjusts the spindle speed and / or the feed rate so that a maximum value of the cutting speed calculated by the cutting speed calculation unit does not exceed the upper limit value detected by the upper limit value detection unit.

[0010] According to the second aspect of the present invention, in the numerical control device according to the first aspect, the speed setting unit can cause the relationship of the set values of the speed of the spindle and the feed rates to change according to a machining program.

[0011] According to a third aspect of the present invention, in the numerical control device according to the first or second aspect, the speed setting unit may cause the ratio of the set values of the speed of the spindle and the feed rate to change according to an input of an operator.

[0012] A program according to a fourth aspect of the present invention is a program for controlling a machine tool, comprising: at least one spindle that causes a cutting tool and a workpiece to rotate relative to each other, and at least one feed axis that causes the cutting tool to move relative to the workpiece, and that cuts the workpiece by means of the cutting tool by causing the spindle and the feed axis to cooperate, the program comprising: an upper limit detection element that detects an upper limit for a cutting speed, which is a relative speed of the cutting tool to the workpiece; a reference speed calculation element that calculates a rotational speed of the spindle and a feed speed, which is a moving speed of the feed axis;an oscillation speed calculation element that calculates an oscillation speed superimposed on the feed rate; a cutting speed calculation element that calculates the cutting speed based on the spindle speed, the feed rate, and the oscillation speed; and a speed adjustment element that adjusts the spindle speed and / or the feed rate so that a maximum value of the cutting speed calculated by the cutting speed calculation element does not exceed the upper limit value detected by the upper limit value detection element.

[0013] A control method according to a fifth aspect of the present invention is a control method for controlling a machine tool, comprising: at least one spindle that causes a cutting tool and a workpiece to rotate relative to each other, and at least one feed axis that causes the cutting tool to move relative to the workpiece, and that cuts the workpiece by means of the cutting tool by causing the spindle and the feed axis to cooperate, the control method comprising the steps of: detecting an upper limit value of a cutting speed, which is a relative speed of the cutting tool to the workpiece; calculating a rotation speed of the spindle and a feed speed, which is a moving speed of the feed axis; calculating an oscillation speed superimposed on the feed speed;Calculating the cutting speed based on the spindle speed, the feed rate, and the oscillation speed; and adjusting the spindle speed and / or the feed rate such that a maximum value of the cutting speed calculated in the cutting speed calculation step does not exceed the upper limit value detected in the upper limit value detection step.

[0014] According to a numerical control apparatus, a program and a control method according to the present invention, the cutting speed of a cutting tool can be prevented from becoming too high when performing oscillating cutting. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the configuration of a machine tool including a numerical control device according to an embodiment of the present invention; Fig. 2 is a view showing the cutting path of a cutting tool on a workpiece surface during machining by the machine tool of the Fig. 1; and Fig. 3 shows a flowchart showing a control sequence of oscillating cutting in the machine tool of Fig. 1 represents. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a block diagram showing the configuration of the machine tool 100 including a numerical control device 1 according to an embodiment of the present invention.

[0016] The machine tool 100 of the present invention is an NC lathe that cuts a workpiece W, which is a machining target, with a cutting tool T. The machine tool 100 includes the three control axes of a spindle Ac that causes a cutting tool and a workpiece to rotate relative to each other (rotates the workpiece W in the present embodiment); a feed axis Az that causes the cutting tool T to move relative to the workpiece W (moves the cutting tool T in the present embodiment); and a cutting axis Ax that causes the cutting tool T to move relative to the workpiece W in the radial direction of the spindle Ac (moves the cutting tool T in the present embodiment).Thus, the machine tool 100 comprises drive motors for driving these control axes Ac, Az, Ax (the spindle motor Mc, the feed axis motor Mz and the one-step axis motor Mx) and servo amplifiers for applying a drive current to the respective drive motors Mc, Mz, Mx (the spindle amplifier Sc, the feed axis amplifier Sz and the one-step axis amplifier Sx).

[0017] The numerical control device 1 controls the machine tool 100, which cuts the workpiece W using the cutting tool T, by cooperatively operating the spindle Ac, the feed axis Az, and the cutting axis Ax. The numerical control device 1 includes a program storage unit 11, a data storage unit 12, an upper limit detection unit 13, a reference speed calculation unit 14, an oscillation speed calculation unit 15, a cutting speed calculation unit 16, a speed setting unit 17, a drive output unit 18, and an input device 19.

[0018] The numerical control device 1 is a device that uses a control method according to the present invention. Furthermore, the numerical control device 1 can be implemented by reading a program according to the present invention into a computer having, for example, a CPU, a memory, etc. The program according to the present invention can be provided by recording it on a non-volatile recording medium. The respective components of the numerical control device 1 are distinguished in terms of their functions and do not necessarily have to be elements that can be clearly separated into the structure of the program for realizing the physical configurations and the numerical control device 1.

[0019] The program storage unit 11 stores a machining program input from the outside. The machining program is written, for example, according to a G-code or the like. The numerical control device 1 machines a workpiece W into a desired shape by controlling the control axes Ac, Az, Ax of the machine tool 100 according to the machining program.

[0020] The data storage unit 12 stores the general information required for machining the workpiece W. For example, the information stored in the data storage unit 12 may include a table or the like that indicates the upper limit value (v Cobergrenze [mm / s]) of the cutting speed (the relative speed (vc [mm / s]) of the cutting tool T with respect to the surface of the workpiece W) for combinations of the respective material properties of a plurality of workpieces W and a plurality of cutting tools T.

[0021] The upper limit value detecting unit 13 refers to the information in the program storage unit 11 and the data storage unit 12 and detects the upper limit value vc Obergrenze the cutting speed for the combination of cutting tool T and workpiece W to be used

[0022] The reference speed calculation unit 14 calculates the spindle speed (S [rpm]), which is the rotational speed of the spindle Ac, and the peripheral speed (f1 [mm / s]) of the workpiece W by rotating the spindle Ac, as well as the feed rate (v1 [mm / s]), which is the moving speed of the feed axis Az, and the feed rate per revolution (F [mm / rev]), which is the feed rate of the cutting tool T per revolution of the spindle Ac, according to the machining program. More specifically, the reference speed calculation unit 14 calculates the spindle speed S, the peripheral speed f1, the feed rate per revolution F, and the feed rate v1 that are optimal when no oscillation control is performed according to the machining shape of the workpiece W described in the machining program. Note that the peripheral speed f1 can be calculated as π · L · S / 60 by using the diameter (L [mm]) of the workpiece W.

[0023] Based on the spindle speed S and the feed rate per revolution F, the oscillation speed calculation unit 15 calculates the oscillation speed (vo(t) [mm / s]), which is a periodic speed fluctuation component superimposed on the feed rate v1 and is a function of time (t [s]). The oscillation speed calculation unit 15 can define the oscillation speed vo(t) as a speed component that fluctuates sinusoidally, so that the position oscillates sinusoidally.

[0024] For example, the oscillation speed calculation unit 15 causes the oscillation position (D [mm]), which is the deviation between the position of the feed axis Az when oscillation control is performed and the position when oscillation control is not performed, to change sinusoidally. More specifically, it is possible to define the frequency of the oscillation position D(t) as a value (S · I ≤ 60 [Hz]) obtained by multiplying a constant (I) by the spindle speed S, and to define the amplitude of the oscillation position D(t) as a value (K · F / 2) obtained by multiplying a constant (K) by the feed rate per revolution F and dividing by 2. In other words, the oscillation position D(t) can be expressed as K · F / 2 · cos(2π / 60 · S · I · t) - K · F / 2.The oscillation velocity Vo(t), which is a value obtained by differentiating the oscillation position D(t), can be calculated as -π / 60 · K · F · S · I sin(2π / 60 · S · I · t).

[0025] The position of the feed axis direction Az of the cutting tool T is expressed as the sum of the integrated values of the feed rate v1 and the oscillation speed vo(t). When this is represented as a change with respect to the rotation angle of the spindle Ac, the cutting trajectory of the cutting tool T during an n-th rotation of the spindle Ac and the cutting trajectory of the cutting tool T during an n-th + 1 rotation of the spindle Ac can be phase-shifted by almost 180° by, for example, setting the constant I to a value close to an odd multiple of 0.5. For this reason, the circumferential direction position of the workpiece W at which the feed direction position of the cutting tool T becomes the maximum during the n-th rotation coincides with the circumferential direction position of the workpiece W at which the feed position of the cutting tool T becomes the minimum during the n-th + 1 rotation.In addition, the cutting path of the cutting tool T during the n-th rotation of the spindle Ac and the cutting path of the cutting tool T during the n-th + 1 rotation of the spindle Ac overlap once per cycle.

[0026] During the period in which the cutting trajectory of the cutting tool T during the n-th rotation of the spindle Ac and the cutting trajectory of the cutting tool T during the n-th + 1 rotation of the spindle Ac overlap with each other, the cutting tool T reaches a state where it is spaced apart from the workpiece W in the direction of the feed axis Az. The generation of chips originating from the material that the cutting tool T cuts away from the workpiece W ends the moment the cutting tool T moves away from the workpiece W. In other words, the chips are separated with each oscillation cycle of the cutting tool T.

[0027] The cutting speed calculation unit 16 calculates the cutting speed vc(t), which is a function of time t, based on the peripheral speed f1, the feed speed v1 and the oscillation speed vo(t), as well as the shape of the workpiece W. More specifically, the cutting speed vc(t) is calculated as the vector sum of the speed calculated by adding the oscillation speed vo(t) to the feed speed vc, the peripheral speed of the workpiece W at the cutting edge position of the cutting tool T and the speed in the direction of the cutting axis Ax of the cutting tool T moving along the shape of the workpiece W.

[0028] In order to reduce the computational load, the cutting speed calculation unit 16 may first calculate the maximum value of the oscillation speed vo(t) and then calculate only the maximum value of the cutting speed vc(t) using the maximum value of the oscillation speed vo(t).

[0029] The speed setting unit 17 sets the peripheral speed f1 and / or the feed speed v1 such that the maximum value of the cutting speed vc(t) calculated by the cutting speed calculation unit 16 exceeds the upper limit value vc Obergrenze , which is detected by the upper limit detection unit 13. In a case where the maximum value of the cutting speed vc(t) calculated by the cutting speed calculation unit 16 exceeds the upper limit vc Obergrenze, the speed setting unit 17 thus changes the peripheral speed f1 and / or the feed speed v1 from the value calculated by the reference speed calculation unit 14 and causes a recalculation in the oscillation speed calculation unit 15 and the cutting speed calculation unit 16.

[0030] The speed setting unit 17 can be configured to adjust only the peripheral speed f1 and the feed rate v1. In this case, by adjusting the peripheral speed f1, the maximum value of the cutting speed vc(t) can be relatively easily kept low enough to exceed the upper limit value vc. Obergrenzedoes not exceed. In addition, in the case where both the peripheral speed f1 and the feed rate v1 are adjusted, the speed adjusting unit 17 may be configured to adjust the peripheral speed f1 and the feed rate v1 such that the ratio of the setting values of the peripheral speed f1 and the feed rate v1 or the contribution of the setting values of the peripheral speed f1 and the feed rate v1 with respect to the change amount of the maximum value of the cutting speed vc(t) becomes constant, configured to perform rough adjustment of the peripheral speed f1 and the feed rate v1 and fine adjustment of each other, or configured to adjust the other only in the case where the adjustment amount of the peripheral speed f1 or the feed rate v1 reaches a predetermined upper limit.

[0031] Furthermore, the speed setting unit 17 can cause the ratio of the setting values of the peripheral speed f1 and the feed rate v1 to change in accordance with another parameter when setting the maximum value of the cutting speed vc(t) (not only in a case of directly determining the ratio of the setting values, but also in a case where the ratio of the setting values changes as a result). The parameter that causes the ratio of the setting values to change can be written into the machining program, or the operator can input it using the input device 19.

[0032] By changing the ratio of the setting values of the peripheral speed f1 and the feed rate v1 when setting the maximum value of the cutting speed vc(t), it is possible to minimize the impact on machining accuracy, machining time, etc., depending on the specific machining (conditions such as the material properties of the workpiece W, the machined shape, the type of cutting tool, etc.). By changing the ratio of the setting values of the peripheral speed f1 and the feed rate v1 in accordance with the machining program, it is possible to reliably optimize each machining operation.Furthermore, by causing the ratio of the setting values of the peripheral speed f1 and the feed rate v1 to change in accordance with the machining program, it is possible to optimize machining even in the case of using a machining program that does not write such a parameter.

[0033] The change in the ratio of the setting values of the peripheral speed f1 and the feed rate v1 not only directly determines the ratio of the setting values of the peripheral speed f1 and the feed rate v1, but can also be caused by determining the upper limit of the setting values of the peripheral speed f1 and the feed rate v1 (including the case where the setting of one of them is disabled) and the amount of contributions of the setting values of the peripheral speed f1 and the feed rate v1 with respect to the change value of the maximum value of the cutting speed vc(t).

[0034] The drive output unit 18 inputs command signals to the spindle amplifier Sc, the feed axis amplifier Sz and the cutting axis amplifier Sx to relatively move the workpiece W and the cutting tool at the set peripheral speed f1, the feed speed v1 and the oscillation speed vo(t).

[0035] As long as the input device 19 allows input by the user, it may be designed as an arrangement including a keyboard, a touch panel, switches, etc., and may be an interface or the like for communication with a terminal or a higher-level control device of the user.

[0036] As is apparent from the above explanation, an embodiment which is a program according to the present invention including the numerical control device 1 may include: an upper limit value detecting element which realizes the upper limit value detecting unit 13 which detects an upper limit value vc Obergrenzefor the cutting speed vc; a reference speed calculation element that implements the reference speed calculation unit 14 that calculates the peripheral speed f1 and the feed rate v1 in accordance with a machining program; an oscillation speed calculation element that implements the oscillation speed calculation unit 15 that calculates the oscillation speed vo(t) based on the peripheral speed f1 and the feed rate v1; a cutting speed calculation element that implements the cutting speed calculation unit 16 that calculates the cutting speed vc(t); and a speed setting element that implements the speed setting unit 17 that sets the peripheral speed f1 and / or the feed rate v1 such that the maximum value of the cutting speed vc(t) exceeds the upper limit value vc Obergrenzedetected by the upper limit detection element.

[0037] In addition, as in Fig. 3, a control method of an embodiment, which is a control method according to the present invention, realized by the numerical control device 1 includes: a step of detecting the upper limit value vc Obergrenzefor the cutting speed vc (step S1: upper limit value acquisition step); a step of calculating the peripheral speed f1 and the feed rate v1 in accordance with a machining program (step S2: reference speed calculation step); a step of calculating the oscillation speed vo(t) based on the spindle speed S and the feed rate v1 (step S3: oscillation speed calculation step); a step of calculating the cutting speed vc(t) (step S4: cutting speed calculation step); a step of setting the peripheral speed f1 and / or the feed rate v1 such that the maximum value of the cutting speed vc(t) exceeds the upper limit value vc Obergrenze does not exceed (step S4: speed setting step); and a step of storing the set cutting speed vc(t) (step S6: storage step).

[0038] The speed setting step in step S5 may include a step for confirming whether the maximum value of the cutting speed vc(t) exceeds the maximum value vc Obergrenze exceeds or not (step S51: confirmation step); and a step of changing the peripheral speed f1 and / or the feed rate v1 in the case where it is determined that the maximum value of the cutting speed vc(t) exceeds the upper limit value vc Obergrenzein the confirmation step in step S51 (step S52): change step). In the case of executing the change step in step S52, the process returns to the oscillation speed calculation step in step S3 to recalculate the oscillation speed vo(t), then the cutting speed vc(t) is recalculated in the cutting speed calculation in step S4, followed by a comparison of the maximum value for the cutting speed vc(t) and the upper limit value vc Obergrenze in the confirmation step in step S51.

[0039] The numerical control device 1, the program for realizing the numerical control device 1, and the control method implemented by the numerical control device 1 can prevent the cutting speed vc(t) from becoming too high when performing oscillating cutting in the machine tool 100, and in particular, can keep the cutting speed vc(t) at a low value not higher than the upper limit value vc Obergrenze Conversely, the numerical control device 1, the program for implementing the numerical control device 1, and the control method implemented by the numerical control device 1 can suppress an increase in machining time by increasing the peripheral speed f1 and the feed rate vz within ranges that limit the cutting speed vc(t) to not more than the upper limit value vc Obergrenze can suppress.

[0040] Although an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. Furthermore, the effects described in the present embodiment are merely a list of the most preferred effects achieved by the present invention, and the effects according to the present invention are not limited to those described in the present embodiment.

[0041] For example, the numerical control device, the program and the control method according to the present invention do not necessarily have to be able to change the ratio of the setting values of the peripheral speed and the feed rate.

[0042] In the numerical control apparatus, program, and control method according to the present invention, the waveform of the oscillation speed is not limited to a sinusoidal waveform, and may periodically change as a sawtooth wave, triangular wave, trapezoidal wave, rectangular wave, or the like.

[0043] The numerical control device, program, and control method according to the present invention can control the spindle speed such that the peripheral speed of the workpiece becomes constant. In other words, in the numerical control device, program, and control method according to the present invention, the peripheral speed can be calculated as a function of time.

[0044] The numerical control apparatus, program and control method according to the present invention are not limited to lathes and can also be applied to, for example, a drilling machine control system or the like. LIST OF REFERENCE SYMBOLS 1 numerical control device 13 Unit for recording the upper limit value 14 Reference speed calculation unit 15 Oscillation speed calculation unit 16 Cutting speed calculation unit 17 Speed adjustment unit 18 Drive output unit 100 machine tools AC spindle Az feed axis T cutting tool W workpiece

Claims

[1] A numerical control device (I) for controlling a machine tool, comprising: at least one spindle (Ac) which causes a cutting tool (T) and a workpiece (W) to rotate relative to each other, and at least one feed axis (Az) which causes the cutting tool (T) to move relative to the workpiece (W) and which cuts the workpiece (W) by means of the cutting tool (T) by causing the spindle (Ac) and the feed axis (Az) to cooperate, the numerical control device (I) comprising: an upper limit value detecting unit (13) that detects an upper limit value for a cutting speed, which is a relative speed of the cutting tool (T) to the workpiece (W); a reference speed calculation unit (14) that calculates a rotational speed of the spindle (Ac) and a feed speed, which is a moving speed of the feed axis (Az); an oscillation speed calculation unit (15) that calculates an oscillation speed superimposed on the feed speed; a cutting speed calculation unit (16) which calculates the cutting speed based on the spindle speed (Ac), the feed rate and the oscillation speed; and a speed setting unit (17) which sets the speed of the spindle (Ac) and / or the feed rate so that a maximum value of the cutting speed calculated by the cutting speed calculation unit (16) does not exceed the upper limit value detected by the upper limit value detection unit (13). [2] A numerical control device (I) according to claim 1, wherein the speed setting unit (17) causes a ratio of setting values of the speed of the spindle (Ac) and the feed rate to change according to a machining program. [3] A numerical control device (I) according to claim 1 or 2, wherein the speed setting unit (17) causes the ratio of the set values of the speed of the spindle (Ac) and the feed rate to change in accordance with an input of an operator. [4] A program for controlling a machine tool, comprising: at least one spindle (Ac) which causes a cutting tool (T) and a workpiece (W) to rotate relative to each other, and at least one feed axis (Az) which causes the cutting tool (T) to move relative to the workpiece (W) and which cuts the workpiece (W) by means of the cutting tool (T) by causing the spindle (Ac) and the feed axis (Az) to cooperate, the program comprising: an upper limit detection element that detects an upper limit for a cutting speed which is a relative speed of the cutting tool (T) to the workpiece (W); a reference speed calculation element that calculates a rotational speed of the spindle (Ac) and a feed rate that is a moving speed of the feed axis (Az); an oscillation speed calculation element that calculates an oscillation speed superimposed on the feed rate; a cutting speed calculation element that calculates the cutting speed based on the spindle speed (Ac), the feed rate and the oscillation speed; and a speed setting element that sets the spindle speed (Ac) and / or the feed rate so that a maximum value of the cutting speed calculated by the cutting speed calculation element does not exceed the upper limit value detected by the upper limit value detection element. [5] A control method for controlling a machine tool, comprising: at least one spindle (Ac) which causes a cutting tool (T) and a workpiece (W) to rotate relative to each other, and at least one feed axis (Az) which causes the cutting tool (T) to move relative to the workpiece (W) and which cuts the workpiece (W) by means of the cutting tool (T) by causing the spindle (Ac) and the feed axis (Az) to cooperate, the control method comprising the following steps: Detecting an upper limit value of a cutting speed, which is a relative speed of the cutting tool (T) to the workpiece (W); Calculating a spindle speed (Ac) and a feed rate, which is a movement speed of the feed axis (Az); Calculating an oscillation speed superimposed on the feed rate; Calculate the cutting speed based on the spindle speed (Ac), the feed rate and the oscillation speed; and Adjusting the spindle speed (Ac) and / or the feed rate such that a maximum value of the cutting speed calculated in the cutting speed calculation step does not exceed the upper limit value detected in the upper limit value detection step.

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