Numerical controller and computer-readable storage medium

Abstract

The numerical controller acquires a variation condition in which the spindle speed periodically varies, calculates the spindle speed that periodically varies on the basis of a variation amplitude rate and a variation frequency rate included in the variation condition, acquires the temperature of the spindle, and when the temperature of the spindle exceeds a predetermined temperature threshold value, calculates the spindle speed that periodically varies. At least one or both of the fluctuation amplitude rate and the fluctuation frequency rate is / are reduced.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a numerical control device and a computer-readable storage medium. BACKGROUND

[0002] Cutting is a kind of removal processing in which a desired shape is formed in a workpiece by relative movement of a tool and the workpiece as a processing target. A machine tool equips the tool or the workpiece to a spindle, and performs cutting by rotating the spindle. In cutting, sometimes "regenerative chatter" occurs. In regenerative chatter, the following phenomenon is repeated: vibration occurs on a processed surface, the cut thickness caused by the previous cutting mark and the present cutting mark becomes vibratory, the cutting force proportional to the cut thickness becomes vibratory, and vibration of the tool or the workpiece is excited.

[0003] To avoid regenerative chatter, there has been a technology in which the spindle speed is varied in a triangular wave or a sinusoidal wave to suppress vibration of the cut thickness. For example, Patent Literature 1.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: International Publication No. 2016 / 181450 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, when the spindle speed is periodically varied, the load on the spindle motor increases, and the temperature of the spindle motor rises. In order not to cause the temperature of the spindle motor to rise, it is necessary to adjust the variation amplitude / variation frequency of the spindle speed. Adjustment of the variation amplitude / variation frequency of the spindle speed is complicated.

[0009] In the field of numerical control devices, it is desirable to simplify adjustment of the variation amplitude / variation frequency of the spindle speed.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] A numerical control device according to an aspect of the present disclosure includes a variation condition acquisition unit that acquires a variation condition in which a spindle speed is periodically varied, a spindle speed calculation unit that calculates a periodically varied vibration spindle speed in accordance with a variation amplitude ratio and a variation frequency ratio included in the variation condition, a temperature acquisition unit that acquires a temperature of the spindle, and a variation ratio calculation unit that reduces one or both of the variation amplitude ratio and the variation frequency ratio when the temperature of the spindle exceeds a predetermined temperature threshold. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a block diagram of a numerical control device according to a first embodiment.

[0013] Figure 2 is a graph showing the relationship between the fluctuation frequency rate and the fluctuation amplitude rate.

[0014] Figure 3 is a flowchart showing the operation of the numerical control device of the first embodiment.

[0015] Figure 4 is a graph showing the changes in the fluctuation amplitude rate and the fluctuation frequency rate in the first embodiment.

[0016] Figure 5 is a graph showing the changes in the fluctuation amplitude rate and the fluctuation frequency rate in the second embodiment.

[0017] Figure 6 is a block diagram of the numerical control device of the fourth embodiment.

[0018] Figure 7 is a graph of the frequency spectrum of the spindle vibration.

[0019] Figure 8 is a flowchart showing the operation of the numerical control device of the fourth embodiment.

[0020] Figure 9 is a graph showing the changes in the fluctuation amplitude rate and the fluctuation frequency rate in the fourth embodiment.

[0021] Figure 10 is a block diagram of the numerical control device of the fifth embodiment.

[0022] Figure 11 is a block diagram of the numerical control device of the sixth embodiment.

[0023] Figure 12 is a flowchart showing the operation of the numerical control device of the sixth embodiment.

[0024] Figure 13 is a screen display diagram of the numerical control device of the sixth embodiment.

[0025] Figure 14 is a hardware configuration diagram of the numerical control device. DETAILED DESCRIPTION

[0026] The numerical control device of the present disclosure has a function of suppressing regenerative chatter. Regenerative chatter refers to vibration caused by undulations of a machined surface produced in one-pass cutting. When vibration is produced on a machined surface in one-pass cutting, the cut thickness becomes vibratory due to the one-pass cutting mark and the current cutting mark. The cutting force proportional to the cut thickness also becomes vibratory, and vibration of the tool or workpiece is excited.

[0027] The numerical control device suppresses vibration by periodically varying the spindle speed. The numerical control device of the embodiment adjusts the amplitude of the spindle speed variation and the variation rate of the frequency. The larger the amplitude and the frequency of the spindle, the greater the effect of suppressing chatter, but the load on the spindle becomes larger and the temperature of the spindle rises. The numerical control device adjusts the variation frequency rate and the variation amplitude rate of the spindle speed, and calculates the variation frequency rate and the variation amplitude rate that suppress the heating of the spindle and suppress chatter.

[0028] (First Embodiment)

[0029] Hereinafter, the numerical control device of the first embodiment will be described.

[0030] Figure 1 is a block diagram of the numerical control device 100 of the first embodiment. The numerical control device 100 has a variation condition acquisition section 10, a spindle speed calculation section 11, a spindle motor control section 12, a temperature acquisition section 13, and a variation rate calculation section 14.

[0031] The variation condition acquisition section 10 acquires the variation condition of the spindle speed. The variation condition includes a variation amplitude rate initial value RVA init , a variation frequency rate initial value RVF init , and a temperature threshold value T th . The variation condition is input by a machine manufacturer who is a user of the machine tool.

[0032] The spindle speed calculation section 11 calculates the spindle speed on the basis of the variation condition, as in the following equation, and outputs it to the spindle motor control section 12. The spindle motor control section 12 controls the motor of the machine tool so that the motor rotates at the specified spindle speed.

[0033] [Mathematical Equation 1]

[0034]

[0035] In the above equation, Ω0 is a reference spindle speed, Ω is a spindle speed, RVA is a variation amplitude rate, and RVF is a variation frequency rate. The reference spindle speed Ω0 is a speed of the spindle specified by a machining program. The spindle speed Ω is a speed obtained by periodically varying the reference spindle speed Ω0. The variation frequency rate RVF is a coefficient for adjusting the frequency of the spindle speed. The variation amplitude rate is a coefficient for adjusting the amplitude of the spindle speed.

[0036] The variation frequency rate initial value RVF init is an initial value of the variation frequency RVF. The variation amplitude rate initial value RVA init is an initial value of the variation amplitude rate RVA.

[0037] Figure 2The relationship between the variation frequency rate RVF and the variation amplitude rate RVA is represented by the following equation. The numerical control device 100 calculates the spindle speed Ω obtained by periodically varying the reference spindle speed Ω0. By periodically varying the spindle speed Ω, the regenerative chatter is suppressed. The variation frequency rate RVF and the variation amplitude rate RVA are coefficients for adjusting the frequency f s and the amplitude A of the spindle speed Ω.

[0038] The following equation represents the relationship between the variation frequency rate RVF, the variation amplitude rate RVA, and the reference spindle speed Ω0.

[0039] [Equation 2]

[0040] The frequency

[0041] The variation frequency rate

[0042] The variation amplitude rate RVA = A / Ω0

[0043] The temperature acquisition unit 13 acquires the temperature of the spindle. The method of acquiring the temperature is not particularly limited. The temperature of the spindle is associated with the amplitude A and the frequency f s of the spindle speed Ω. The greater one of the amplitude A and the frequency f s , the higher the temperature of the spindle.

[0044] The variation rate calculation unit 14 compares the temperature of the spindle with the temperature threshold value T th , and if the temperature of the spindle exceeds the temperature threshold value T th , decreases at least one of the variation frequency rate RVF and the variation amplitude rate RVA. If either one of the variation frequency rate RVF and the variation amplitude rate RVA is decreased, the temperature of the spindle decreases. The variation rate calculation unit 14 makes a determination as follows: if the temperature of the spindle is the temperature threshold value T th or more, the cutting is interrupted, and if it is less than the temperature threshold value T th , the cutting is continued.

[0045] The flowchart of FIG. Figure 3 is referred to to describe the operation of the numerical control device 100 of the first embodiment.

[0046] First, the variation condition acquisition unit 10 acquires the variation condition (step S1). The spindle speed calculation unit 11 calculates the spindle speed according to the variation rate (step S2). The initial variation rate is the variation amplitude rate initial value RVA init and the variation frequency rate initial value RVF init acquired by the variation condition acquisition unit 10.

[0047] The operator operates the numerical controller 100, and the machine tool starts cutting (step S3). The temperature acquisition unit 13 acquires the temperature of the spindle.

[0048] The variation magnification calculation unit 14 compares the spindle temperature with the temperature threshold T th When the spindle temperature is less than the temperature threshold T th In the case of (step S4; No), the variable magnification calculation unit 14 does not change the variable magnification and continues cutting (step S5). th In the above case (step S4 ; YES), the variation magnification calculation unit 14 decreases the variation magnification (at least one of the variation amplitude rate RVA and the variation frequency rate RVF) (step S6 ).

[0049] The variable magnification calculation unit 14 waits for a certain time (step S7), and compares the temperature of the spindle with the temperature threshold T th When the spindle temperature is less than the temperature threshold T th When the spindle temperature is the temperature threshold value T th In the above case (step S8 ; No), the variable magnification calculation unit 14 interrupts the cutting (step S9 ).

[0050] As described above, the numerical controller 100 of the first embodiment obtains the temperature of the spindle, and when the temperature of the spindle exceeds the temperature threshold T th When the spindle speed Ω is set to the amplitude f s At least one of the frequency and the frequency A decreases. The numerical control device 100 obtains the temperature of the spindle. If the temperature of the spindle is lower than the temperature threshold T th , then continue cutting. If the spindle temperature is greater than the temperature threshold T th , cutting is interrupted. Thus, the variation ratio (variation amplitude rate RVA, variation frequency rate RVF) of the periodic variation of the spindle speed Ω is automatically adjusted to suppress the temperature rise of the spindle. The numerical controller 100 automatically adjusts the spindle temperature, reducing the burden on the operator.

[0051] (Second embodiment)

[0052] The numerical controller 100 of the second embodiment reduces the variation amplitude rate RVA and the variation frequency rate RVF to their minimum values. The configuration of the numerical controller of the second embodiment is substantially the same as that of the first embodiment, so only the differences will be described.

[0053] The change condition acquisition unit 10 generates the change amplitude rate initial value RVA in addition to the change amplitude rate initial value RVA. init , initial value of the frequency rate RVF init , temperature threshold Tth In addition, the minimum value of the amplitude rate of change RVA is also obtained min , minimum value of the frequency of change RVF min .

[0054] The variation magnification calculation unit 14 compares the spindle temperature with the temperature threshold T th When the spindle temperature exceeds the temperature threshold T th When the frequency rate RVF is reduced to the minimum frequency rate RVF min , or reduce the amplitude rate RVA to the minimum amplitude rate RVA min , or do both.

[0055] Figure 4 The variation magnification calculation unit 14 shows the change of the variation amplitude rate RVA and the variation frequency rate RVF. th At the time t', the variation ratio is reduced to the minimum value. Among the methods for reducing the variation ratio, there are (1) reducing the variation amplitude ratio RVA from the initial value RVA init Reduce to the minimum value of the amplitude rate of change RVA min (2) Change the variable frequency rate RVF from the variable frequency rate initial value RVF init Reduce to the minimum value of the frequency of change RVF min , or (3) a method that performs both (1) and (2).

[0056] If the variation magnification is reduced, the temperature of the spindle decreases. The variation magnification calculation unit 14 waits for a certain time. Even if the variation magnification is reduced, if the temperature of the spindle reaches the temperature threshold T th If the temperature is not above the threshold value T, the cutting is interrupted. th If above, continue cutting.

[0057] According to the numerical controller 100 of the second embodiment, the load applied to the spindle motor can be quickly reduced by reducing the variation magnification to the minimum value at once.

[0058] (Third embodiment)

[0059] The numerical controller 100 of the third embodiment gradually reduces the variation amplitude rate RVA and the variation frequency rate RVF. The configuration of the numerical controller 100 of the third embodiment is substantially the same as that of the first embodiment, so only the differences will be described.

[0060] The change condition acquisition unit 10 generates the change amplitude rate initial value RVA in addition to the change amplitude rate initial value RVA. init , initial value of the frequency rate RVF init , temperature threshold T thIn addition to this, the rate of change in amplitude slope RVA coef , the rate of change in frequency slope RVF coef .

[0061] The rate of change calculation section 14 compares the temperature of the spindle with the temperature threshold T th , and when the temperature of the spindle exceeds the temperature threshold T th , gradually reduces the rate of change in frequency RVA or the rate of change in amplitude RVF, or both.

[0062] Figure 5 indicates the change in the rate of change in amplitude RVA and the rate of change in frequency RVF. The rate of change calculation section 14 reduces the rate of change at the time t' when the temperature of the spindle exceeds the temperature threshold T th , at a predetermined time, at a predetermined slope. In the method of reducing the rate of change, there are (1) reducing the rate of change in amplitude RVA at a predetermined time (referred to as Δt time), at the rate of change in amplitude slope RVA coef , (2) reducing the rate of change in frequency RVF at a predetermined time (referred to as Δt time), at the rate of change in frequency slope RVF coef , and (3) performing both of (1) and (2).

[0063] If the rate of change is reduced, the temperature of the spindle decreases. With regard to the rate of change calculation section 14, even if the rate of change is reduced, if the temperature of the spindle is equal to or greater than the temperature threshold T th or more, cutting is interrupted, and if it is less than the temperature threshold T th , cutting is continued.

[0064] In the numerical control device 100 of the third embodiment, while reducing the rate of change, the change in the temperature of the spindle motor is confirmed, and at the stage when the temperature of the spindle motor sufficiently decreases, the reduction of the rate of change is stopped. According to the numerical control device 100 of the third embodiment, at the stage when the temperature condition of the spindle motor is satisfied, the reduction of the rate of change is stopped, whereby it is possible to continue cutting at a greater rate of change, and the effect of suppressing regenerative chatter is improved.

[0065] (Fourth Embodiment)

[0066] The numerical control device 100 of the fourth embodiment has a function of frequency analysis, compares the regenerative chatter with a predetermined threshold while adjusting the rate of change in frequency RVA and the rate of change in amplitude RVA, and calculates the rate of change in frequency RVA and the rate of change in amplitude RVA that suppresses the regenerative chatter to the predetermined threshold and does not cause the temperature of the spindle to exceed the temperature threshold T th .

[0067] Figure 6is a block diagram of the numerical control device 100 of the fourth embodiment. The numerical control device 100 of the fourth embodiment has the reproduction chatter detection section 15. The structure of the numerical control device 100 of the fourth embodiment is substantially the same as that of the numerical control device 100 of the third embodiment, and therefore only the different parts will be described.

[0068] The variation condition acquisition section 10 acquires, in addition to the variation amplitude rate initial value RVA init , the variation frequency rate initial value RVF init , the temperature threshold value T th , the variation amplitude rate slope RVA coef , the variation frequency rate slope RVF coef , the chatter threshold value K th (or the calculation formula of the chatter threshold value K th ).

[0069] The variation rate operation section 14 compares the temperature of the spindle with the temperature threshold value T th , and if the temperature of the spindle is T th or more, gradually reduces the variation frequency rate RVF or the variation amplitude rate RVA, or both. The method of gradual reduction is the same as in the third embodiment, and therefore the description is omitted.

[0070] The reproduction chatter detection section 15 detects reproduction chatter. The detection method of reproduction chatter is (1) a method of performing frequency spectrum analysis on signals such as cutting force, displacement, cutting sound, and current, (2) a method of taking the root mean square of the above signals, (3) a method of using machine learning such as Deep Learning, and the like.

[0071] Figure 7 An example of a frequency spectrum is shown. The reproduction chatter detection section 15 performs Fourier transform on the vibration of the spindle, and acquires a frequency spectrum. In Figure 7 , the horizontal axis is the frequency, and the vertical axis is the spectrum of the amplitude corresponding to the frequency. In the vibration of a machine in cutting, a plurality of frequencies are mixed in a complex manner. When frequency analysis is performed, the cutting edge of a tool appears strongly through the frequency component and its higher harmonic component. The frequency of the higher harmonic component is an integer multiple of the cutting edge passing frequency. The reproduction chatter detection section 15 discriminates the cutting edge passing vibration and strong vibrations other than the higher harmonic component as reproduction chatter.

[0072] In the method of taking the root mean square of signals, the root mean square is taken in the time domain with respect to the above signals, and thereby the effective value of the signals is calculated. Also, by determining the size of the level of the effective value, it is possible to detect the occurrence of reproduction chatter.

[0073] In addition, in the method using deep learning, a learning model that extracts a regenerative chatter from an input signal is prepared in advance, and the learning model is used to detect a regenerative chatter signal generated in the signal.

[0074] The variation ratio calculation section 14 calculates a variation frequency rate RVF and a variation amplitude rate RVA that make the regenerative chatter signal converge in the allowable range. In the above-described method of taking the root mean square, the variation frequency rate RVF and the variation amplitude rate RVA are calculated so that the effective value of the signal becomes equal to or less than a predetermined threshold value. In the method using deep learning, for example, a learning model that determines whether the regenerative chatter signal converges in the allowable range is prepared.

[0075] In the method using spectral analysis, the amplitude of the regenerative chatter obtained by Fourier transform is compared with the chatter threshold value K th . The chatter threshold value K th indicates the allowable limit of the regenerative chatter. The chatter threshold value K th is a limit value that does not affect the cutting.

[0076] An example of the chatter threshold value K th is shown in the drawing. In this example, a calculation formula of the chatter threshold value K th is defined. The calculation formula takes a coefficient times the maximum value of the amplitudes of the higher harmonics of the through frequency as the chatter threshold value K th . The variation ratio calculation section 14 selects the maximum value of the amplitudes of the higher harmonics from the amplitude spectrum, multiplies the selected maximum value by a certain coefficient, and calculates the chatter threshold value K th .

[0077] The variation ratio calculation section 14 compares the chatter threshold value K th with the amplitude of the regenerative chatter, and if the amplitude of the regenerative chatter is smaller than the chatter threshold value K th , the variation ratio is decreased. When the variation ratio (one or both of the variation amplitude rate RVA and the variation frequency rate RVF) is decreased, the amplitude of the regenerative chatter gradually increases. The variation ratio calculation section 14 stops the decrease of the variation ratio when the amplitude of the regenerative chatter reaches the chatter threshold value K th .

[0078] The variation amplitude rate RVA at the point of time when the amplitude of the regenerative chatter reaches the chatter threshold value K th is referred to as a variation amplitude rate set value RVA set , and the variation frequency rate RVF is referred to as a variation frequency rate set value RVF set .

[0079] The variation ratio calculation section 14 continues the cutting with the variation ratio fixed to the set value, and compares the temperature of the spindle with a temperature threshold value T th . With regard to the variation ratio calculation section 14, if the temperature of the spindle is smaller than the temperature threshold value Tth then the cutting is continued, if the temperature of the spindle is the temperature threshold value T th The above interrupts the cutting.

[0080] Referring to Figure 8 the flowchart, the operation of the numerical control device 100 of the fourth embodiment will be described. In the flowchart, a case where the regenerative chatter is detected using spectrum analysis is exemplified. The detection method of the regenerative chatter can not be the spectrum analysis.

[0081] First, the variation condition acquisition section 10 acquires the variation condition (step S21). The spindle speed calculation section 11 calculates the spindle speed (step S22). The initial variation rate is the variation amplitude rate initial value RVA init and the variation frequency rate initial value RVF init .

[0082] The operator operates the numerical control device 100, and the machine tool starts the cutting (step S23). The temperature acquisition section 13 acquires the temperature of the spindle.

[0083] The variation rate calculation section 14 compares the temperature of the spindle with the temperature threshold value T th . In a case where the temperature of the spindle is less than the temperature threshold value T th (step S24; No), the variation rate calculation section 14 does not change the variation rate, and the cutting is continued (step S25). In a case where the temperature of the spindle is the temperature threshold value T th or more (step S24; Yes), the variation rate calculation section 14 reduces the variation rate (at least one of the variation amplitude rate RVA or the variation frequency rate RVF) (step S26).

[0084] The variation rate calculation section 14 compares the amplitude of the regenerative chatter with the chatter threshold value K th . If the amplitude of the regenerative chatter is less than the chatter threshold value K th (step S27; No), the variation rate calculation section 14 shifts to step S26, and reduces the variation rate. As long as the amplitude of the regenerative chatter does not exceed the chatter threshold value K th , the variation rate calculation section 14 reduces the variation rate. When the amplitude of the regenerative chatter is the chatter threshold value K th or more (step S27; Yes), the variation rate calculation section 14 sets the variation rate that does not exceed the range of the chatter threshold value K th to the set value of the variation rate (the variation amplitude rate set value RVA set and the variation frequency rate set value RVF set ).

[0085] The variation rate calculation section 14 compares the temperature of the spindle with the temperature threshold value T thWhen the spindle temperature is the temperature threshold T th If the temperature is above the threshold value T (step S28; yes), the variable magnification calculation unit 14 interrupts the cutting (step S29). th (Step S28; No), the variable magnification calculation unit 14 continues cutting (Step S30).

[0086] Figure 9 The fourth embodiment shows the change of the amplitude rate RVA and the frequency rate RVF. init And the initial value of the frequency rate RVF init To calculate the spindle speed Ω. If the initial value of the amplitude rate of change RVA init And the initial value of the frequency rate RVF init Make the spindle temperature lower than the temperature threshold T when the spindle speed changes th , the variable rate calculation unit 14 reduces the variable rate. Among the methods for reducing the variable rate, there are (1) using the variable frequency slope RVF coef Reduce the variable frequency RVF, (2) change the amplitude slope RVA coef Reduce the fluctuation amplitude rate RVA, and (3) perform both (1) and (2).

[0087] If the variation ratio is reduced, the amplitude of the regenerative chattering will gradually increase. th The time is set as t', then the variable frequency rate RVF and the variable amplitude rate RVA at t' are fixed to the variable frequency rate setting value RVF set And the amplitude rate setting value RVA set .

[0088] The variable magnification calculation unit 14 determines the variable frequency setting value RVF set And the amplitude rate setting value RVA set Whether the spindle temperature during cutting exceeds the temperature threshold T th As a result, the spindle temperature does not exceed the temperature threshold T th If the spindle temperature exceeds the temperature threshold T th Cutting is interrupted in case of

[0089] According to the numerical control device 100 of the fourth embodiment, it is possible to automatically search for the variation amplitude rate RVA and the variation frequency rate RVF that suppress the regenerative chatter vibration within the allowable range and suppress the temperature of the main shaft within the allowable range.

[0090] (Fifth embodiment)

[0091] The numerical control device 100 of the fifth embodiment stores the variation ratio calculated by the variation ratio calculation section 14 in correspondence with the program blocks of the machining program. Figure 10 is a block diagram of the numerical control device 100 of the fifth embodiment. The numerical control device 100 of the fifth embodiment has a variation ratio storage section 16 that stores the program blocks of the machining program in correspondence with the variation ratios (variation amplitude ratio and variation frequency ratio). Figure 10 The structure of the numerical control device of the fifth embodiment shown is substantially the same as the numerical control device 100 of the first embodiment, and therefore only the different parts will be described. Further, the function of the variation ratio storage section 16 can also be applied to the numerical control devices 100 of the second to fourth embodiments and the sixth embodiment.

[0092] According to the numerical control device 100 of the fifth embodiment, by storing the program blocks of the machining program in correspondence with the variation ratios, the variation ratios that have already been calculated when the same machining program is executed can be used. Thus, without the readjustment of the variation ratios, the physical load related to the spindle, the computational load required for the adjustment of the spindle speed, and the like can be reduced.

[0093] (Sixth Embodiment)

[0094] The numerical control device 100 of the sixth embodiment displays the variation ratios and the temperature changes of the spindle at and after the cutting interruption, and when the spindle is cooled to a predetermined set value, the variation ratios are newly set and the cutting is restarted.

[0095] Figure 11 is a block diagram of the numerical control device 100 of the sixth embodiment. The numerical control device 100 of the sixth embodiment has a display control section 17. The structure of the numerical control device 100 of the sixth embodiment is substantially the same as the numerical control device 100 of the first embodiment, and therefore only the different parts will be described. Further, the function of the numerical control device 100 of the sixth embodiment can also be applied as a function after the cutting interruption in the numerical control devices 100 of the first to fifth embodiments.

[0096] The display control section 17 causes at least the variation amplitude ratio RVA, the variation frequency ratio RVF, and the temperature of the spindle at and after the cutting interruption to be displayed as a graph and a numerical value on the display section 70. Further, it is also possible to cause the variation amplitude ratio RVA, the variation frequency ratio RVF, and the temperature of the spindle to be displayed on the display section 70 from before the cutting interruption.

[0097] The variation ratio calculation section 14 compares the temperature of the spindle after the interruption of cutting with a predetermined set value, and when the temperature of the spindle is cooled to the set value, the values of the variation amplitude ratio RVA and the variation frequency ratio RVF at the time of interruption of cutting are reset to the variation amplitude ratio initial value RVA init and the variation frequency ratio initial value RVF init .

[0098] Referring to Figure 12 the flowchart, the operation of the numerical control device 100 of the sixth embodiment will be described.

[0099] When the temperature of the spindle exceeds the temperature threshold value T th , the variation ratio calculation section 14 interrupts the cutting (step S31). After the interruption of cutting, the variation ratio calculation section 14 acquires the temperature of the spindle, and determines whether the temperature of the spindle is equal to or lower than a predetermined set value. In the case where the temperature of the spindle is greater than the predetermined set value (step S32; No), the variation ratio calculation section 14 stands by for a certain time (step S33), and compares the temperature of the spindle with the predetermined set value again.

[0100] In the case where the temperature of the spindle is equal to or lower than the predetermined set value (step S32; Yes), the variation ratio calculation section 14 resets the values of the variation amplitude ratio RVA and the variation frequency ratio RVF at the time of interruption of cutting to the variation amplitude ratio initial value RVA init and the variation frequency ratio initial value RVF init (step S34). The variation ratio calculation section 14 restarts the cutting with the variation amplitude ratio initial value RVA init and the variation frequency ratio initial value RVF init that are reset (step S35).

[0101] After the interruption of cutting, the display control section 17 causes the variation amplitude ratio RVA, the variation frequency ratio RVF, the graph of the temperature of the spindle, and the numerical value to be displayed on the display section 70. Figure 13 is an example of a display screen that indicates the changes in the variation amplitude ratio RVA, the variation frequency ratio RVF, and the temperature of the spindle at the time of repeated interruption of cutting and restart. The variation amplitude ratio RVA and the variation frequency ratio RVF are gradually decreasing, and the variation amplitude ratio RVA at the current time is "0.16", and the variation frequency ratio RVF is "0.10". According to the changes in the variation amplitude ratio RVA and the variation frequency ratio RVF, the temperature of the spindle is also decreasing, and the temperature of the spindle at the current time is "121 degrees". The temperature of the spindle exceeds the temperature threshold value T th , and it is necessary to reset the variation conditions.

[0102] This display screen is an example of the display screen of the second embodiment. In this display screen, the minimum value of the variation amplitude ratio RVA minand a variation frequency rate minimum value RVF min In the display screen of the third embodiment, the variation amplitude rate slope RVA coef and the variation frequency rate slope RVF coef In the display screen of the fourth embodiment, the frequency component of the reproduction chatter can be displayed.

[0103] According to the numerical control device 100 of the sixth embodiment, after the interruption of the cutting, the variation amplitude rate RVA and the variation frequency rate RVF at the time of the interruption of the cutting are reset to the variation amplitude rate initial value RVA init and the variation frequency rate initial value RVF init Thereby, the variation condition can be automatically set.

[0104] Further, in the numerical control device 100 of the sixth embodiment, the variation amplitude rate RVA, the variation frequency rate RVF, and the temperature of the spindle after the interruption of the cutting are displayed on the display section 70. The values of the variation amplitude rate RVA and the variation frequency rate RVF are automatically controlled, but by displaying the values associated with the control, the operator can confirm the control state.

[0105] Hereinafter, the hardware structure of the numerical control device 100 to which the present disclosure is applied will be described. Figure 14 is a hardware structure diagram of the numerical control device 100. As Figure 14 indicated, the numerical control device 100 has a CPU 111 that controls the numerical control device 100 as a whole, a ROM 112 that records a program and data, a RAM 113 that is used to temporarily expand data, the CPU 111 reads out a system program recorded in the ROM 112 via a bus, and executes avoidance of the reproduction chatter in accordance with the system program.

[0106] The nonvolatile memory 114 is backed up by a battery or the like not shown, and maintains a storage state even if the power of the numerical control device 100 is turned off. In the nonvolatile memory 114, a program read from the external device 120 via the interfaces 115, 118, 119, various data input via the input section 30, and the like are stored. The program and data for executing the numerical control device 100 of the present embodiment can also be stored in the nonvolatile memory 114. Further, various data, measurement results, reasons for improper data, and the like are displayed on the display section 70.

[0107] The interface 115 is an interface for connecting the numerical control device 100 and the external device 120 such as an adapter. A program, various parameters, and the like are read from the external device 120 side.

[0108] The interface 118 is an interface for connecting the numerical control device 100 and the display section 70 such as a liquid crystal display. The display section 70 displays each data read into the memory, data obtained as a result of executing a program, and the like.

[0109] The interface 119 is an interface for connecting the numerical control device 100 and the input section 30 such as a keyboard and a pointing device. The input section 30 transmits instructions, data, and the like according to operations of an operator to the CPU 111 via the interface 119.

[0110] The present disclosure has been described in detail, but the present disclosure is not limited to the above-described embodiments. The embodiments can be variously added, replaced, changed, partially deleted, or the like within a range not departing from the gist of the present disclosure, or within a range not departing from the gist of the present disclosure derived from the contents described in the range to be claimed and equivalents thereof. In addition, the embodiments can be implemented in combination. For example, in the above-described embodiments, the order of each action, the order of each process is indicated as an example, and is not limited thereto.

[0111] With respect to the above-described embodiments and modified examples, the following supplementary notes are also disclosed.

[0112] (Supplementary Note 1)

[0113] The numerical control device 100 includes a variation condition acquisition section 10 that acquires a variation condition that causes a spindle speed to periodically vary, a spindle speed calculation section 11 that calculates a vibration spindle speed that periodically varies, based on a variation amplitude ratio and a variation frequency ratio included in the variation condition, a temperature acquisition section 13 that acquires a temperature of the spindle, and a variation ratio calculation section 14 that reduces one or both of the variation amplitude ratio and the variation frequency ratio when the temperature of the spindle exceeds a predetermined temperature threshold.

[0114] (Supplementary Note 2)

[0115] The variation ratio calculation section 14, after reducing one or both of the variation amplitude ratio and the variation frequency ratio, interrupts cutting when the temperature of the spindle exceeds the predetermined temperature threshold, and continues cutting when the temperature of the spindle does not exceed the predetermined threshold.

[0116] (Supplementary Note 3)

[0117] The variation amplitude ratio is a coefficient of an amplitude of the spindle speed, and the variation frequency ratio is a coefficient of a frequency of the spindle speed.

[0118] (Supplementary Note 4)

[0119] The variation condition acquisition section 10 acquires one or both of the minimum value of the variation amplitude ratio and the minimum value of the variation frequency ratio, and the variation ratio operation section 14 reduces the variation amplitude ratio to the minimum value, or reduces the variation frequency ratio to the minimum value, or reduces both to the minimum values when the temperature of the spindle exceeds a predetermined temperature threshold.

[0120] (Embodiment 5)

[0121] The variation condition acquisition section 10 acquires one or both of the slope of the variation amplitude ratio and the slope of the variation frequency ratio, and the variation ratio operation section 14 reduces the variation amplitude ratio with the slope of the variation amplitude ratio, or reduces the variation frequency ratio with the slope of the variation frequency ratio, or reduces both when the temperature of the spindle exceeds a predetermined temperature threshold.

[0122] (Embodiment 6)

[0123] The numerical control device 100 has a regenerative chatter detection section 15 that detects a regenerative chatter, and the variation ratio operation section 14 reduces one or both of the variation amplitude ratio and the variation frequency ratio until the regenerative chatter converges to an allowable range.

[0124] (Embodiment 7)

[0125] The variation ratio operation section 14 continues the cutting while maintaining the variation amplitude ratio and the variation frequency ratio at the point in time when the amplitude of the regenerative chatter reaches a predetermined amplitude threshold, interrupts the cutting when the temperature of the spindle exceeds a predetermined temperature threshold, and continues the cutting in the case where the temperature of the spindle does not exceed the predetermined threshold.

[0126] (Embodiment 8)

[0127] The numerical control device 100 has a variation ratio storage section 16 that stores a program block of a machining program in association with the variation amplitude ratio and the variation frequency ratio calculated by the variation ratio operation section 14 when the program block is executed.

[0128] (Embodiment 9)

[0129] The variation ratio operation section 14 stands by until the temperature of the spindle decreases to a predetermined set value after the cutting is interrupted, re-sets the variation amplitude ratio and the variation frequency ratio at the time of interruption of the cutting to initial values, and re-starts the cutting.

[0130] (Embodiment 10)

[0131] The numerical control device 100 has a display control section 17 that causes a display section to display changes in the variation amplitude ratio and the variation frequency ratio.

[0132] (Embodiment 11)

[0133] The computer-readable storage medium 112, 113, 114 stores commands that cause the one or more processors 111 to perform the following processing: acquire a variation condition that causes the spindle speed to periodically vary, calculate the spindle speed that periodically varies based on a variation amplitude ratio and a variation frequency ratio included in the variation condition, acquire the temperature of the spindle, and reduce at least one or both of the variation amplitude ratio and the variation frequency ratio when the temperature of the spindle exceeds a predetermined temperature threshold.

[0134] Symbol explanation

[0135] 100 numerical control device,

[0136] 10 variation condition acquisition section,

[0137] 11 spindle speed calculation section,

[0138] 12 spindle motor control section,

[0139] 13 temperature acquisition section,

[0140] 14 variation ratio calculation section,

[0141] 15 reproduction chatter detection section,

[0142] 16 variation ratio storage section,

[0143] 17 display control section,

[0144] 111 CPU,

[0145] 112 ROM,

[0146] 113 RAM,

[0147] 114 nonvolatile memory.

Claims

1. A numerical control device, characterized in that: have: a variation condition acquisition unit that acquires a variation condition for periodically varying the spindle speed; a spindle speed calculation unit for calculating a periodically varying vibrating spindle speed based on a variation amplitude rate and a variation frequency rate included in the variation condition; a temperature acquiring unit that acquires the temperature of the spindle; and The variation magnification calculation unit reduces one or both of the variation amplitude rate and the variation frequency rate when the temperature of the spindle exceeds a predetermined temperature threshold.

2. The numerical control device according to claim 1, wherein The variation magnification calculation unit reduces one or both of the variation amplitude rate and the variation frequency rate, and then interrupts cutting if the temperature of the spindle exceeds a predetermined temperature threshold, and continues cutting if the temperature of the spindle does not exceed the predetermined threshold.

3. The numerical control device according to claim 1, wherein The fluctuation amplitude rate is a coefficient of the amplitude of the spindle speed, and the fluctuation frequency rate is a coefficient of the frequency of the spindle speed.

4. The numerical control device according to claim 1, wherein The variation condition acquisition unit acquires one or both of the minimum value of the variation amplitude rate and the minimum value of the variation frequency rate. When the temperature of the spindle exceeds a predetermined temperature threshold, the variation magnification calculation unit reduces the variation amplitude rate to a minimum value, reduces the variation frequency rate to a minimum value, or reduces both to minimum values.

5. The numerical control device according to claim 1, wherein The change condition acquisition unit acquires one or both of the slope of the change amplitude rate and the slope of the change frequency rate. When the temperature of the spindle exceeds a predetermined temperature threshold, the variation magnification calculation unit reduces the variation amplitude rate according to the slope of the variation amplitude rate, reduces the variation frequency rate according to the slope of the variation frequency rate, or reduces both.

6. The numerical control device according to claim 1, wherein The numerical control device includes: a regenerative vibration detection unit that detects regenerative vibration; The variation magnification calculation unit reduces one or both of the variation amplitude rate and the variation frequency rate until the regenerative judder falls within an allowable range.

7. The numerical control device according to claim 6, characterized in that The variation magnification calculation unit continues cutting by maintaining the variation amplitude rate and the variation frequency rate at the time point when the amplitude of the regenerative chatter reaches a predetermined amplitude threshold, interrupts cutting when the temperature of the spindle exceeds a predetermined temperature threshold, and continues cutting when the temperature of the spindle does not exceed the predetermined threshold.

8. The numerical control device according to claim 1, wherein The numerical control device includes a variation magnification storage unit that stores a program block of a machining program in association with a variation amplitude rate and a variation frequency rate calculated by the variation magnification calculation unit when the program block is executed.

9. The numerical control device according to claim 2, wherein: The variation magnification calculation unit waits until the temperature of the spindle decreases to a predetermined set value after the cutting is interrupted, resets the variation amplitude rate and the variation frequency rate at the time of the cutting interruption to initial values, and resumes cutting.

10. The numerical control device according to claim 9, characterized in that The numerical control device includes a display control unit configured to display changes in the fluctuation amplitude rate and the fluctuation frequency rate on a display unit.

11. A computer-readable storage medium, characterized in that: Storing instructions that cause one or more processors to: Obtaining a change condition for periodically changing the spindle speed; Calculating the periodically changing spindle speed based on the change amplitude rate and the change frequency rate included in the change condition; Get the spindle temperature; When the temperature of the spindle exceeds a predetermined temperature threshold, at least one or both of the fluctuation amplitude rate and the fluctuation frequency rate are reduced.

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