machine tool

Abstract

Machine tool, featuring: a rotating shaft which is configured to allow a tool (14) or a workpiece to be attached to it, a drive unit that is connected to the rotating shaft to make the rotating shaft rotate, a rotary shaft control unit configured to regulate the drive unit to change a rotational speed (S) of the rotary shaft in such a way that the rotational speed (S) oscillates with a given amplitude and a given time period (R) with respect to a given mean rotational speed, a machine tool control unit (8) which is configured to change predetermined parameters, including at least one of the mean rotational speed, the amplitude and the duration (R), where the machine tool a display device (9) and a parameter display control device (11) which is configured to display the display device (9) parameter information, which is information relating to the parameters, in order to change the parameters based on the parameter information displayed in the display device (9), characterized in that the parameter information displayed in the display device (9) includes at least one of a value or range of values ​​of a first predetermined parameter that is effective against regenerative chatter vibrations, wherein the first predetermined parameter is the time period (R) which is derived from the formula: main spindle pendulum period [ s ] = 120 m ( 2 n − 1 ) N is obtained, whereby m a number of flutes of the tool (14) is, n is an integer, and N is a mean rotational speed of the rotating shaft, and a value or range of values ​​of a second predetermined parameter that is ineffective against the regenerative chatter vibrations, wherein the second predetermined parameter is the time period (R) which is derived from the formula: main spindle pendulum period [ s ] = 60 mn N will be received.

Description

[0001] The present invention generally relates to a machine tool that performs a machining operation on a workpiece with a tool while rotating the tool or the workpiece.

[0002] For example, a machine tool in which a tool rotates to cut a workpiece surface may experience chatter vibrations generated during its cutting operation for several reasons, such as low tool rigidity or the like. As a method for suppressing chatter vibrations, a method of periodically varying the rotational speed of the main spindle within a predetermined range (amplitude), as described in Japanese Patent Application Laid-Open Nos. 49-105277 and 2000-126991, is known in the art.

[0003] Typically, however, the amplitude and duration of a periodic change (oscillation) in the main spindle speed are determined empirically by an operator. This means that an operator should be sufficiently experienced when determining how to effectively suppress chatter vibrations. With the existing method mentioned above, it is very difficult for an inexperienced operator to achieve satisfactory chatter suppression, and depending on the situation, an undesirable reduction in the yield of machined products is inevitable.

[0004] There is a need to provide a machine tool with which even an operator with little experience can easily achieve effective suppression of chatter vibrations and yield improvement can be expected.

[0005] The documents JP 2000-126 991 A and JP H08-229 772 A disclose a machine tool comprising a rotary shaft to which a tool or a workpiece can be attached, a drive unit connected to the rotary shaft to rotate the rotary shaft, a rotary shaft control unit that regulates the drive unit to change a rotational speed of the rotary shaft in such a way that the rotational speed oscillates with a given amplitude and a given time period with respect to a given average rotational speed, a machine tool control unit that changes predetermined parameters to thereby change at least one of the average rotational speed, the amplitude and the time period.The machine tool includes a display device and a parameter display control device that makes the display device display parameter information that is information regarding the parameters to make the parameters change based on the parameter information displayed in the display device.

[0006] Document JP 2005-144 580 A discloses a machine tool having a rotating shaft whose speed is substantially continuously increased and decreased.

[0007] Document US 2008 / 0 058 982 A1 discloses a machine tool control system which has a display device and an input means as a user interface.

[0008] The present invention has been made to address the need and eliminate the aforementioned disadvantages, and illustrative, non-limiting embodiments of the present invention overcome the above disadvantages and other disadvantages not described above.

[0009] The problem is solved by the features of claim 1. Advantageous further developments are the subject of the subclaims. (1) According to one aspect of the present invention, there is provided a machine tool with a chatter vibration suppression mechanism, which includes a rotating shaft configured to allow a tool or a workpiece to be mounted thereon, and a drive unit connected to the rotating shaft to rotate the rotating shaft. The drive unit is controlled to change a rotating speed of the rotating shaft in such a manner that the rotating speed oscillates with respect to a given average rotating speed with a given amplitude and a given time period. It is possible to change predetermined parameters to thereby change at least one of the average rotating speed, the amplitude, and the time period.The machine tool further includes a display device and a parameter display control unit configured to have the display device display parameter information, which is information regarding the parameters, to enable the parameters to be changed based on the parameter information displayed in the display device. (2) In the machine tool configured as described in (1) above, the parameter information displayed in the display device may include at least one of: (i) a value or range of values ​​of a parameter effective against regenerative chatter vibrations; and (ii) a value or range of values ​​of a parameter that is ineffective against regenerative chatter vibrations. (3) In the machine tool configured as described in (1) or (2) above, the parameter information displayed in the display device may include a value range of a parameter according to which it is impossible to control the drive unit. (4) In the above configuration (1) with or without the additional features (2) and / or (3), the predetermined parameters may include the amplitude and the time duration. (5) In the above configuration (1) with or without the additional features (2) and / or (3), the predetermined parameters may include: (a) either the amplitude or the duration, and (b) at least one of an angular acceleration of the rotating shaft, a torque of the rotating shaft, an amount of electric power supplied to the drive unit, a rate of change obtained by dividing the amplitude by the time period, and the average speed.

[0010] According to the above configuration (1), the average speed is a reference speed with respect to which the speed oscillates with a given amplitude and a given time duration.

[0011] With the configurations described above, various beneficial effects can be expected, as follows.

[0012] According to the aspect of the present invention mentioned in (1) above, the machine tool includes the display unit and the parameter display control unit configured to allow the display device to display parameter information, and the parameters can be changed based on the parameter information displayed in the display device. Therefore, with this machine tool, chatter vibration suppression can be achieved more effectively than any existing machine tool, and the yield of machined products can be improved accordingly, even if an operator has little experience.

[0013] With any of the configurations described in (2) above, in which the parameter display control unit has the display device display information regarding the parameters, a value or a range of values ​​of each parameter effective against regenerative chatter vibrations and / or a value or a range of values ​​of a parameter ineffective against regenerative chatter vibrations, even a less experienced operator can achieve effective suppression of chatter vibrations more and more easily and reliably.

[0014] With the configuration (3) described above, the parameter display control device can have the display device display a value range of a parameter, according to which it is impossible to control the drive unit, as information regarding the parameter. Accordingly, it is possible to prevent an undesirable situation in which, for example, an operator inputs a value that requires a torque of the rotating shaft beyond its maximum value, the input value is thus deemed invalid, and the machining process proceeds without necessary changes that should affect the amplitude or the duration of the oscillation of the rotating shaft speed, with the result that the chatter vibrations cannot be suppressed. Consequently, with this configuration, the chatter vibrations can be suppressed with greater reliability.

[0015] With the configurations described in (4) and (5) above, in which the parameters include the amplitude and the time period, or either the amplitude or the time period and also at least one of an angular acceleration of the rotating shaft, a torque of the rotating shaft, an amount of electric power supplied to the drive unit, a change rate obtained by dividing the amplitude by the time period, and the average rotational speed, the amplitude and the time period of oscillation of the rotating shaft rotational speed can be changed more easily.

[0016] The above aspect, other advantages and further features of the present invention will become more apparent by describing in detail illustrative, non-limiting embodiments thereof with reference to the accompanying drawings. Fig. 1 is a schematic block diagram of a machining center as an example of a machine tool. Fig. 2 is a schematic diagram graphically indicating that a rotational speed of a main spindle oscillates with a given amplitude and a given time period. Fig. 3 is a schematic diagram showing an example of a display representation of information regarding parameters and the like in a display device. Fig. 4 is a schematic diagram of a modified example of a display representation of information regarding parameters and the like in the display device.

[0017] A machine tool according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0018] A machining center 1, as an example of a machine tool, includes a main spindle 2 as an example of a rotating shaft, to which a tool 14 can be installed via a holder 13. The machining center 1 further includes a spindle head 3 in which the main spindle 2 and some other components, such as a motor 4 and an encoder 5, are housed. The main spindle 2 is rotatably supported in the spindle head 3, and the motor 4 is configured to rotate the main spindle 2. The encoder 5 is configured to detect the rotational speed of the main spindle 2 or the motor 4. The machine tool 1 also includes a table 6 arranged in a position opposite the spindle head 3 and configured to allow a workpiece W to be placed thereon.

[0019] A main spindle control unit 7, configured to control the rotational speed of the main spindle 2 and regulate the amount of electric power supplied to the motor 4, is electrically connected to the motor 4 and the encoder 5. A machine tool control unit 8, configured to control the entire operation (behavior) of the machining center 1, is connected to the main spindle control unit 7 as well as to a storage unit 10, a parameter display control unit 11, and an input device 12. The storage unit 10 is configured to store a machining program. The parameter display control unit 11 includes a display device 9, which will be described later. The input device 12 is configured to receive instructions to the machine tool control unit 8 to change the rotational speed, or the like.

[0020] In this machine tool (machining center) 1, a machining program stored in the storage unit 10 is read out therefrom to perform predetermined functions including supplying electric power to the motor 4 to rotate the main spindle 2 and changing a rotational speed of the rotation shaft in such a manner that the rotational speed is changed under control of the main spindle control unit 7 with a given amplitude and a given time period with respect to a given average rotational speed (rotational speed s in Fig. 4) oscillates when the machine tool control unit 8 receives instructions through the input device 12 to start a machining operation so that a surface or the like of a workpiece W is cut and machined. When chatter vibration occurs, the operator can change predetermined parameters (e.g., the amplitude and time duration in this embodiment) using the input device 12 based on information regarding the parameters (see below for details) displayed on the display device 9, thereby changing the amplitude and time duration of the oscillation of the rotational speed of the main spindle 2. Accordingly, the rotational speed of the main spindle 2 oscillates at an amplitude and time duration according to the values ​​of the parameters input (changed) by the operator, so that chatter vibration can be suppressed.Meanwhile, the machine tool control unit 8 stores the values ​​of the parameters effective for suppressing chatter vibration and / or the amplitude and time period given according to the parameter values ​​in the storage unit 10. In the future machining operations, from the next time, the rotational speed of the main spindle 2 is caused to oscillate from the beginning with the amplitude and time period stored in the storage unit 10 (in cases where only the values ​​of the parameters are stored therein, the amplitude and time period can be calculated from the values ​​of the stored parameters).

[0021] Oscillation of the speed of the main spindle 2 generated by the main spindle control unit 7 can, for example, as shown in Fig. 2, in which the speed oscillates with an amplitude Q and a time period R. Alternatively, the oscillation of the speed does not necessarily have to be in the form of a Fig. 2, but may instead be in the form of a sine wave or a trapezoidal wave. The amplitude Q and the period R of the oscillation of the rotational speed of the main spindle 2 can be assumed to be the parameters that can be changed, and other variables can also be assumed as parameters. For example, it should be noted that the following simple equation (1) has been proven to be effective: Q=1500πSJ(T−Tc)R Q: Amplitude of the pendulum of the speed [%] R: Duration of the oscillation of the speed [s] S: Speed ​​of the main spindle [min -1 ] J: Mass inertia of a rotating body [kgm 2 ] T: Main spindle torque [Nm] Tc: Cutting torque [Nm] where Q is a value obtained by dividing the amplitude of the oscillating speed by an average speed, R is a period of oscillation, and J is a mass inertia. Accordingly, the main spindle torque T (torque of the main spindle 2) can be substituted for the period R and taken in combination with the amplitude Q as the predetermined parameters. That is, the machining center 1 can be configured to make the amplitude Q and the period R of the oscillation of the speed of the main spindle 2 changeable by allowing the amplitude Q and the main spindle torque T to be changed through the input device 12. The mass inertia J in formula (1) is a value determined by the types of the main spindle 2, the holder 13, and the tool 14, or other factors.

[0022] It should also be noted that the relationship between the main spindle torque T and the main spindle angular acceleration (angular acceleration of the main spindle 2) is represented by the following formula (2), and thus the main spindle angular acceleration can be substituted for the main spindle torque T and taken in combination with the amplitude Q as the predetermined parameters. Furthermore, the relationship between the main spindle torque T and the electric power supplied to the motor 4 is represented by the following formula (3), and thus the electric power supplied to the motor 4 can be substituted for the main spindle torque T and taken in combination with the amplitude Q as the predetermined parameters. ω˙=(T−Tc)J ώ: Angular acceleration of the main spindle [rad / s 2 ] P=πS30T P: electrical power supply [W]

[0023] Hereinafter, some examples of a display representation in the display device 9 generated by the parameter display control unit 11 will be described with reference to the Fig. 3 and Fig. 4 described.

[0024] When the main spindle 2 is rotated to start the machining process, as shown in Fig. 3, processing information and parameter information are displayed in the display device 9. The parameter information is information regarding parameters for suppressing chatter vibrations (information indicating parameter values ​​that can be changed or values ​​suggested for better selection). Fig. 3, the processing information displayed on the right side contains information about an oscillation of the speed of the main spindle 2 (“speed” in Fig. 3), information about a change in the torque of the main spindle 2 (“torque” in Fig. 3) and information about a vibration acceleration obtained by a vibration sensor (not shown) that detects vibrations occurring on the main spindle 2 (“acceleration” in Fig. 3). The machining information, which is also displayed on the left side, contains information about the number of chip flutes of the tool 14 used and information about the average speed of the main spindle 2 during the machining process.

[0025] On the other hand, in the Fig. 3, the parameters are predetermined to be the amplitude Q and the time period R of the oscillation of the speed (ie the amplitude Q and the time period R are changeable by the input device 12). In Fig. 3, a current setting (ie, currently set amplitude and time duration) is used as the parameter information on a planar rectangular coordinate system having an ordinate and an abscissa indicating the amplitude and time duration, respectively, as in Fig. 3 as a solid circle. It is known that effective suppression of the so-called regenerative chatter vibrations is only achieved at some limited time duration values, and the effective time durations and the ineffective time durations are represented by the following formulas (4) and (5), respectively. Accordingly, in the example of Fig. 3 Time periods obtained from the formula (4) and predetermined ranges whose average values ​​are set at the obtained time periods (ie, each extending from the obtained value minus a predetermined value to the obtained value plus the predetermined value) are set as ranges of the time periods effective for suppressing chatter vibrations, and displayed by assigning a designating color thereto in the planar rectangular coordinate system. To suppress the chatter vibration, effective main spindle pendulum time [s] = 120m(2n−1)N to suppress the chatter vibration ineffective main spindle pendulum time [s] = 60mnN m : number of chip flutes n : integer N : average speed of the main spindle [min -1 ]

[0026] Candidates for average speeds effective for suppressing chatter vibrations can be obtained from formula (4) with a set time period, and a predetermined number of the obtained candidates can also be displayed as parameter information in order, starting with the candidate closest to the current speed. In this way, the average speed can also be changed by the operator through the input device 12 (e.g., the average speed with respect to which the speed oscillates is changed with the amplitude, and the time period remains unchanged).

[0027] Alternatively or additionally, a planar rectangular coordinate system having an ordinate and an abscissa indicating the time period R and the average speed N, respectively, on which a current setting is plotted (i.e., currently set time period and average speed), may be provided. Accordingly, a value or a range of values ​​of the time period R and the average speed N effective for suppressing chatter vibrations and / or a value or a range of values ​​of the time period R and the average speed N ineffective in suppressing chatter vibrations may be indicated by assigning a designating color thereto in the planar rectangular coordinate system.

[0028] Meanwhile, it is known that excessive supply of electric power to the motor 4 would cause the motor 4 to overheat or otherwise damage the motor 4. In view of this, in order to prevent such an undesirable situation, the machine tool control unit 8 is configured to limit the maximum value of the torque of the main spindle 2. Accordingly, there are cases where the amplitude Q of the oscillation of the rotational speed of the main spindle 2 could not be changed to a larger value, or the time period R of the oscillation of the rotational speed of the main spindle 2 could not be changed to a smaller value. To be more specific, the ranges within which the amplitude Q and the time period R can be changed are limited by the following formula (6), which is derived from the above-mentioned formula (1).

[0029] Therefore, the parameter display control unit 11 is configured to explicitly display ranges of the amplitudes and the time durations as the parameter information in the planar rectangular coordinate system (range referred to as “setting not possible” in Fig. 3) that fail to satisfy formula (6), so that an operator is prevented from entering any parameter values ​​in the ranges that fail to satisfy formula (6). Q≤1500TπSJ(Tmax−Tc)R T max : Maximum value of the torque of the main spindle [Nm]

[0030] It should be understood that the inertia J in formula (6) can be calculated from the material or shape of the holder 13 or the tool 14, or from formula (1) with the main spindle torque T, the amplitude Q, and the time period R during no-load operation (idle operation). The cutting torque Tc can be calculated from the shape of the tool 14, the specific cutting resistance, and cutting conditions, or can be determined by subtracting the main spindle torque during no-load operation from the main spindle torque during a current cutting operation of the workpiece W.

[0031] Although the example display of Fig. 3 are the amplitude Q and the time period R, the parameters to be predetermined need not be limited to this. For example, a display representation in the display device 9 in which an amplitude Q and an angular acceleration are assumed as the parameters is shown in Fig. 4. In the example of Fig. 4, processing information and parameter information are also displayed in the display device 9, and in the example of Fig. 4 is essentially the same as that shown in the example of Fig. 3. On the other hand, a current setting (ie, currently set amplitude and angular acceleration) on a plane rectangular coordinate system having an ordinate and an abscissa indicating the amplitude Q and the angular acceleration, respectively, is represented as a filled circle in Fig. 4, plotted as the parameter information. Furthermore, it is known that the amplitude Q, the time period R, and the angular acceleration have a relationship as expressed by the following formula (7). By substituting the above-mentioned formula (4) into the formula (7), the relationship between the amplitude Q and the angular acceleration, which produces an effect for suppressing regenerative chatter vibrations, is obtained as expressed by the following formula (8). Therefore, in the example of Fig. 4 time periods obtained from the formula (4), and predetermined ranges whose average values ​​are respectively set at the obtained time periods (ie, each extending from the obtained value minus a predetermined value to the obtained value plus the predetermined value) are substituted into the following formula (8) to obtain ranges of the amplitudes and the angular accelerations effective for suppressing chatter vibrations, the ranges of which are indicated by assigning a designating color thereto in the planar rectangular coordinate system. Q=1500πSRω˙ ω̇: Angular acceleration of the main spindle [rad / s 2 ] Q=1500×120πS2m(2n−1)ω˙

[0032] Since the maximum value of the torque of the main spindle 2 is limited, the range within which the angular acceleration can be changed is limited by the following formula (9), which is derived from the above-mentioned formula (2). Accordingly, the parameter display control unit 11 is configured to explicitly display the range of the angular acceleration that fails to satisfy formula (9) in the planar rectangular coordinate system as the parameter information (range referred to as "setting impossible" in Fig. 4) so ​​that an operator is prevented from entering any parameter values ​​in the range that fails to satisfy formula (9). ω˙≤Tmax−TcJ

[0033] It is appreciated that any variables other than the parameters for changing the amplitude Q and the period R of the speed oscillation may be adopted. For example, instead of the period R and the angular acceleration, the main spindle torque or the electric power supplied to the motor 4 in combination with the amplitude Q may be adopted as the parameters. In these embodiments, the parameter display control unit 11 may be configured to display parameter information, for example, by plotting a variety of information on a planar rectangular coordinate system having an ordinate and an abscissa, each indicating the amplitude Q and the main spindle torque. Alternatively, the angular acceleration, the main spindle torque, and the electric power supply may be adopted in combination with the period R.Furthermore, a change rate can be obtained by dividing the amplitude Q by the time period R, so that the change rate and the amplitude Q can be taken as the parameters, or the change rate and the time period R can be taken as the parameters. On the other hand, unlike the examples of . Fig. 3 and Fig. 4, in which only the value ranges of the parameters effective for suppressing regenerative chatter vibrations are displayed, value ranges of the parameters that can be obtained from the above-mentioned formula (5) that are ineffective in suppressing regenerative chatter vibrations are also displayed as the parameter information.

[0034] With the machining center 1 configured according to the present embodiment, when chatter vibration occurs, predetermined parameters can be changed, and the rotational speed of the main spindle 2 is changed in such a way that the rotational speed oscillates with an amplitude Q and a time period R adjusted according to the changed parameters. Information regarding the predetermined parameters is displayed by the parameter display control unit 11 on the display device 9. Accordingly, based on the information displayed on the display device 9, an operator can change parameter values ​​and change the amplitude Q and the time period R of the oscillation of the rotational speed of the main spindle 2.Therefore, with this configuration, even if an operator has little experience, the suppression of chatter vibration can be achieved more effectively than with any existing machine tools, and thus the yield of the machined products can be increased accordingly.

[0035] Furthermore, the amplitude Q and the time period R can be changed more easily because the amplitude Q and the time period R are adopted as the predetermined parameters, or the angular acceleration of the main spindle 2, the torque of the main spindle 2, the amount of electric power supplied to the motor 4, or the rate of change in combination with either the amplitude Q or the time period R are adopted as the predetermined parameters.

[0036] Furthermore, since a value range of the predetermined parameters effective for suppressing regenerative chatter vibrations is displayed as information regarding the parameters in the display device 9, even a less skilled operator can easily suppress chatter vibrations without failure.

[0037] Furthermore, in the present embodiment, a value range of the predetermined parameters which would require a change in the amplitude Q and the time period R which entails an excessive load applied to the motor 4 (i.e., the value range of the predetermined parameters corresponding to the torque of the main spindle 2 would exceed its maximum value) and thus cannot be applied is displayed in the display device 9 as the information regarding the predetermined parameters to alert an operator that the value range should not be inputted so that the torque of the main spindle 2 will not exceed the maximum value.Therefore, it is possible to prevent an undesirable situation in which an operator enters a value requiring a torque of the main spindle 2 that exceeds its maximum value, the entered value is deemed invalid, and the machining process continues without making necessary changes to the amplitude Q and the period R of the oscillation of the main spindle 2 speed, resulting in chatter vibrations not being suppressed. As a result, with this configuration, chatter vibrations can be suppressed with high reliability.

[0038] Additionally, in this embodiment, the changed parameter values ​​or the amplitude Q and the time period R corresponding to the parameter values ​​are stored in the storage unit 10, so that in the subsequent operation, from the beginning, the rotational speed of the main spindle 2 is caused to oscillate with the amplitude Q and time period R stored in the storage unit 10. Therefore, the chatter vibrations can be suppressed with a higher degree of reliability.

[0039] The machine tool to which the present invention is applicable is not limited to the above-described embodiment, and the rotary shaft, the parameter display control unit, the machine tool control unit, and the entire arrangement of the machine tool can be appropriately modified on a required basis without departing from the scope of the present invention.

[0040] For example, in the above-described embodiment, the machining center having a rotary shaft configured to allow a tool to be mounted thereon was exemplified as a machine tool consistent with the present invention. However, any other type of machine tool, such as a lathe having a rotary shaft configured to allow a workpiece to be mounted thereon so that the workpiece rotates instead of the tool, can be implemented accordingly with the present invention.

[0041] In the embodiment described above, the parameter display control unit 11 is configured to display the machining information as well as the parameter information on the display device 9. However, it is by no means necessary to display the machining information. The machining information may be displayed separately from the parameter information displayed on the display device 9, that is, it may be displayed on a different display device.

[0042] Additionally, in the above-described embodiment, parameter value ranges that would require a change in the amplitude Q and the time period R, which would result in an excessive load being applied to the motor 4, are displayed only on the display device 9. However, it is also possible to provide a machine tool configured to make it impossible to input such parameter value ranges into the input device 12.

Claims

[1] Machine tool, comprising: a rotary shaft configured to allow a tool (14) or a workpiece to be attached thereto, a drive unit connected to the rotating shaft to rotate the rotating shaft, a rotary shaft control unit configured to regulate the drive unit to change a rotational speed (S) of the rotary shaft in such a way that the rotational speed (S) oscillates with a given amplitude and a given time period (R) with respect to a given average rotational speed, a machine tool control unit (8) configured to change predetermined parameters to change at least one of the average speed, the amplitude and the time period (R), where the machine tool a display device (9) and a parameter display control device (11) configured to allow the display device (9) to display parameter information, which is information regarding the parameters, in order to allow the parameters to be changed based on the parameter information displayed in the display device (9), characterized by that the parameter information displayed in the display device (9) includes at least one of a value or a range of values ​​of a first predetermined parameter which is effective against regenerative chatter vibrations, wherein the first predetermined parameter is the time period (R) which is determined from the formula: main spindle pendulum time period [s]=120m(2n−1)N is obtained, where m is a number of chip flutes of the tool (14), n is an integer, and N is an average speed of the rotating shaft, and a value or a range of values ​​of a second predetermined parameter which is ineffective against the regenerative chatter vibrations, wherein the second predetermined parameter is the time period (R) which is determined from the formula: main spindle pendulum time period [s]=60mnN is received. [2] A machine tool according to claim 1, wherein the parameter information displayed in the display device (9) includes a value range of a parameter according to which the drive unit cannot be controlled. [3] A machine tool according to any one of claims 1 or 2, wherein the predetermined parameters include the amplitude. [4] A machine tool according to claim 1 or 2, wherein the predetermined parameters include at least one of an angular acceleration of the rotating shaft, a torque of the rotating shaft, an amount of electric power supplied to the drive unit, a rate of change obtained by dividing the amplitude by the time period, and the average rotation speed. [5] A machine tool according to claim 4, wherein the predetermined parameters include the amplitude.

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