Numerical control device and computer-readable storage medium

Abstract

A numerical control device is provided which obtains a variation state for periodically varying a spindle speed, which calculates a periodically varying spindle speed based on a variation amplitude ratio and a variation frequency ratio included in the variation condition, obtains the temperature of the spindle and, if the temperature of the spindle exceeds a predetermined temperature threshold, decreases at least one or both of the variation amplitude ratio and the variation frequency ratio.

Description

Technical field

[0001] The present disclosure relates to a numerical control device and a computer-readable storage medium. Related state of the art

[0002] Machining is a type of material removal in which a desired shape is created on the workpiece through relative motion between a tool and a workpiece. In a machine tool, a tool or workpiece is mounted on a spindle, and the spindle is then rotated to perform the machining operation. During machining, "regenerative chatter" can occur. Regenerative chatter is characterized by the following phenomena occurring repeatedly: vibrations occur on a cutting edge; the cutting thickness becomes wave-like due to the previous and current cutting paths; the cutting force, which is proportional to the cutting thickness, also becomes wave-like; and the tool or workpiece is set into vibration.

[0003] To prevent the occurrence of regenerative chatter vibration, a conventional technique exists in which the spindle speed is converted into a triangular or sinusoidal wave in order to eliminate the vibration in the cutting thickness. Such a technique is disclosed, for example, in patent literature 1. State of the art document (patent literature)

[0004] [Patent Literature 1] International PCT Publication No. 2016 / 181450 Summary of the invention: Problems to be solved by the invention

[0005] However, if the spindle speed is varied periodically, the load on the spindle motor increases, leading to a rise in the spindle motor's temperature. To prevent this temperature increase, it is necessary to adjust the variable amplitude / frequency of the spindle speed. Adjusting the variable amplitude / frequency of the spindle speed is complex.

[0006] Therefore, there is a need for a technique to simplify the setting of the variable amplitude / variable frequency of the spindle speed. Facilities to solve the problem

[0007] One embodiment of the present disclosure is a numerical control device comprising: a variation condition acquisition unit that acquires variation conditions for a periodic variation of the spindle speed; a spindle speed calculation unit that calculates an oscillating spindle speed that varies periodically based on a variable amplitude rate and a variable frequency rate included in the variation conditions; a temperature acquisition unit that acquires the temperature of a spindle; and a variation magnification calculation unit that decreases one of the variable amplitude rates and the variable frequency rate, or both, when the temperature of the spindle exceeds a predefined temperature threshold. Brief description of the drawings

[0008] They show: Fig. 1 a block diagram of a numerical control device according to a first embodiment; Fig. 2 a schematic diagram showing a relationship between a variable frequency rate and a variable amplitude rate; Fig. 3 a flowchart showing the operation of the numerical control device according to the first embodiment; Fig. 4 a graph showing changes in the variable amplitude rate and the variable frequency rate in the first embodiment; Fig. 5 a graph showing changes in the variable amplitude rate and the variable frequency rate in a second embodiment; Fig. 6 a block diagram of a numerical control device according to a fourth embodiment; Fig. 7 a graph of a frequency spectrum of spindle vibrations; Fig. 8 a flowchart showing the operation of the numerical control device according to the fourth embodiment; Fig. 9 a graph showing the changes of a variable amplitude rate and a variable frequency rate in the fourth embodiment; Fig. 10 a block diagram of a numerical control device according to a fifth embodiment; Fig. 11 a block diagram of a numerical control device according to a sixth embodiment; Fig. 12 a flowchart showing the operation of the numerical control device according to the sixth embodiment; Fig. 13 a diagram of a screen display of the numerical control device according to the sixth embodiment; and Fig. 14 a hardware configuration diagram of the numerical control device. Mode for executing the invention

[0009] A numerical control device of the present disclosure has a function for eliminating regenerative chatter vibration. Regenerative chatter vibration is caused by roughness on a surface to be machined, which is previously created by cutting with a blade. If vibrations are generated on the surface to be machined during the previous cutting operation by the cutting tool, the cutting force becomes wavy due to the previous cutting path of the cutting tool and the current cutting path. Consequently, the cutting force, which is proportional to the cutting force, also becomes wavy, causing a tool or workpiece to vibrate.

[0010] The numerical control device is configured to eliminate vibrations by periodically varying the spindle speed. According to the illustrative embodiment, the numerical control device adjusts the amplitude and frequency variation ratio of the spindle speed. The greater the spindle amplitude and frequency, the greater the chatter suppression effect. However, this also increases the load on the spindle and consequently its temperature. The numerical control device adjusts the spindle speed by varying the frequency and amplitude rates and calculates these values ​​to control spindle heating and eliminate chatter. (First embodiment)

[0011] A numerical control device according to a first embodiment is described below.

[0012] Fig. Figure 1 shows a block diagram of a numerical control device 100 according to the first embodiment. The numerical control device 100 comprises a variation condition acquisition unit 10, a spindle speed calculation unit 11, a spindle motor control unit 12, a temperature acquisition unit 13, and a variation magnification calculation unit 14.

[0013] The variation condition acquisition unit 10 is configured to acquire variation conditions set for a spindle speed. The variation conditions include an initial value of the variable amplitude rate RVA. init , an initial value of the variable frequency rate RVF init and a temperature threshold T th The variation conditions are entered by a machine manufacturer who is a user of a machine tool.

[0014] The spindle speed calculation unit 11 is configured to calculate a spindle speed using the formula described below, based on the variation conditions, and to output the result of the calculation to the spindle motor control unit 12. The spindle motor control unit 12 is configured to control a motor of the machine tool such that the motor rotates at a specified spindle speed. Ω=Ω0×RVA×sin(2πNΩ0⋅RVF60t)

[0015] In the formula described above, the term Ω0 is a reference spindle speed, the term Ω is a spindle speed, the term RVA is a variable amplitude rate, and the term RVF is a variable frequency rate. The reference spindle speed Ω0 is a spindle speed defined in a machining program. The spindle speed Ω is a periodically varied speed of the reference spindle speed Ω0. The variable frequency rate RVF is a coefficient used to adjust the frequency of the spindle speed. The variable amplitude rate is a coefficient used to adjust the amplitude of the spindle speed.

[0016] The initial value of the variable frequency rate RVF init is an initial value of the variable frequency RVF. The initial value of the variable amplitude rate RVA. init is an initial value of the variable amplitude rate RVA.

[0017] Fig. Figure 2 shows a relationship between the variable frequency rate RVF and the variable amplitude rate RVA. The numerical control device 100 calculates the spindle speed Ω, which is obtained by periodically varying the reference spindle speed Ω0. By periodically varying the spindle speed Ω, the regenerative chatter vibration can be eliminated. The variable frequency rate RVF and the variable amplitude rate RVA are coefficients used to adjust a frequency f s or an amplitude A of the spindle speed Ω can be used.

[0018] The formula described below gives a relationship between the variable frequency rate RVF, the variable amplitude rate RVA and the reference spindle speed Ω0. Frequency fs=1T Variable frequency rate RVF=60fsNΩ0 Variable amplitude rate RVA=AΩ0

[0019] The temperature acquisition unit 13 is configured to acquire the temperature of the spindle. The method for acquiring the temperature is not limited to a specific procedure. The temperature of the spindle is related to the amplitude A and the frequency f. s the spindle speed Ω. The higher either the amplitude A or the frequency f s The larger the spindle, the higher the spindle temperature.

[0020] The variation magnification calculation unit 14 is configured to measure the spindle temperature with the temperature threshold T. th to compare, and if the spindle temperature exceeds the temperature threshold T thIf the variable frequency rate (RVF) and the variable amplitude rate (RVA) are exceeded, at least one of them must be reduced. Reducing either the variable frequency rate (RVF) or the variable amplitude rate (RVA) can lower the spindle temperature. The variation magnification calculation unit 14 determines to interrupt cutting when the spindle temperature is greater than or equal to the temperature threshold T. th is, or to continue cutting when the temperature is lower than the temperature threshold T th is,

[0021] The operation of the numerical control device 100 of the first embodiment is described with reference to a flowchart in Fig. 3 described.

[0022] First, the variation condition acquisition unit 10 acquires variation conditions (step S1). Then, the spindle velocity calculation unit 11 calculates a spindle velocity based on a variation magnification (step S2). The initial variation magnifications are the initial value of the variable amplitude rate RVA. init and the initial value of the variable frequency rate RVF init , which are obtained by the variation condition acquisition unit 10.

[0023] An operator activates the numerical control device 100 to put a machine tool into cutting mode (step S3). The temperature acquisition unit 13 reaches the temperature of a spindle.

[0024] The variation magnification calculation unit 14 compares the spindle temperature with the temperature threshold T. th If the spindle temperature is lower than the temperature threshold T thIf (step S4: No), the variation magnification calculation unit 14 continues cutting without changing the variation magnification (step S5). If the spindle temperature is greater than or equal to the temperature threshold T th If (step S4: Yes), the variation magnification calculation unit 14 reduces the variation magnification (at least either the variable amplitude rate RVA or the variable frequency rate RVF) (step S6).

[0025] The variation magnification calculation unit 14 waits for a predefined time (step S7) and then compares the spindle temperature with the temperature threshold T. th If the spindle temperature is lower than the temperature threshold T th If (step S8: No), the variation magnification calculation unit 14 continues cutting (step S10). If the spindle temperature is greater than or equal to the temperature threshold T thIf (step S8: No), the variation magnification calculation unit 14 interrupts the cutting (step S9).

[0026] As described above, the numerical control device 100 according to the first embodiment obtains the temperature of the spindle and reduces at least either the amplitude f s or the frequency A of the spindle's vibration Ω, when the spindle's temperature exceeds the temperature threshold T th The numerical control device 100 reaches the spindle temperature and resumes cutting when the spindle temperature falls below the temperature threshold T. th The cutting process will stop, or be interrupted, if the spindle temperature exceeds the temperature threshold T. thThis means that the variation magnification for the periodic variation of the spindle speed Ω (variable amplitude rate RVA, variable frequency rate RVF) is automatically adjusted to prevent an increase in spindle temperature. The numerical control device 100 automatically adjusts the spindle temperature, thus reducing the workload for the operator. (Second example)

[0027] The numerical control device 100 according to a second embodiment reduces the variable amplitude rate RVA and the variable frequency rate RVF to their minimum values. The configuration of the numerical control device according to the second embodiment is largely the same as that of the numerical control device according to the first embodiment, so only the different functions in the configuration are described.

[0028] The variable state acquisition unit 10 is configured to provide an initial value of the variable amplitude rate RVA. init and an initial value of the variable frequency rate RVF init a minimum value of the variable amplitude rates RVA min and a minimum value of the variable frequency rate RVF min to obtain.

[0029] The variation magnification calculation unit 14 is configured to measure the temperature of a spindle with a temperature threshold T. th to compare, and if the spindle temperature exceeds the temperature threshold T th If exceeded, then the variable frequency rate RVF is set to the minimum value of the variable frequency rate RVF min to reduce or to lower the variable amplitude rate RVA to the minimum value of the variable amplitude RVA min to reduce or to carry out both processes.

[0030] Fig. Figure 4 shows the changes in the variable amplitude rate RVA and the variable frequency rate RVF. The variation magnification calculation unit 14 reduces the variation magnification to the minimum value at a time t' when the spindle temperature exceeds the temperature threshold T. th exceeds. The reduction of the variation magnification is implemented such that (1) the variable amplitude rate RVA is reduced from the initial value of the variable amplitude rate RVA. init to the minimum value of the variable amplitude rate RVA min (2) the variable frequency rate RVF is reduced from the initial value of the variable frequency rate RVF init to the minimum value of the variable frequency rate RVF min is reduced or (3) both (1) and (2) are carried out.

[0031] Reducing the variation magnification leads to a decrease in the spindle temperature. The variation magnification calculation unit 14 waits for the predefined time and then interrupts the cutting process when the spindle temperature is greater than or equal to the temperature threshold T. th is, even if the variation magnification is reduced, or continues cutting if the spindle temperature is not higher than the temperature threshold T th is.

[0032] According to the numerical control device 100 of the second embodiment, the load on a spindle motor can be quickly reduced by reducing the variation magnification to its minimum value all at once. (Third embodiment)

[0033] The numerical control device 100 according to a third embodiment gradually reduces the variable amplitude rate RVA and the variable frequency rate RVF. The configuration of the numerical control device 100 according to the third embodiment is largely the same as that of the numerical control device according to the first embodiment, so only the different functions in the configuration are described.

[0034] The variable state acquisition unit 10 is configured to have a variable amplitude rate slope RVA. coef and a variable frequency rate slope RVF coef in addition to an initial value of the variable amplitude rate RVA init , an initial value of the variable frequency rate RVF init and a temperature threshold T th to obtain.

[0035] The variation magnification calculation unit 14 is configured to measure the temperature of a spindle with the temperature threshold T. th to compare, and if the spindle temperature exceeds the temperature threshold T th If the limit is exceeded, then decrease the variable frequency rate RVF or the variable amplitude rate RVA, or gradually decrease both rates.

[0036] Fig. Figure 5 shows changes in the variable amplitude rate RVA and the variable frequency rate RVF. The variation magnification calculation unit 14 reduces a variation magnification for a predetermined time at a predetermined slope at a time t' when the spindle temperature exceeds the temperature threshold T. th exceeds. The reduction of the variation magnification is carried out such that (1) the variable amplitude rate RVA for the predetermined time (denoted as time Δt) at the variable amplitude rate slope RVA coef(2) the variable frequency rate RVF for the predetermined time (referred to as time Δt) with the variable frequency rate slope RVF coef is reduced, or (3) both (1) and (2) are carried out.

[0037] Reducing the variation magnification leads to a decrease in the spindle temperature. The variation magnification calculation unit 14 interrupts the cutting process when the spindle temperature is greater than or equal to the temperature threshold T. th is, even if the variation magnification is reduced, or continues cutting if the spindle temperature is not higher than the temperature threshold T th is.

[0038] The numerical control device 100 of the third embodiment monitors the change in temperature of a spindle motor while the variation magnification is reduced and stops the reduction of the variation magnification when the temperature of the spindle motor has decreased sufficiently. According to the numerical control device 100 of the third embodiment, by stopping the reduction of the variation magnification when the temperature condition of the spindle motor is met, cutting can be continued with a higher variation magnification, thereby improving the suppression effect on regenerative chatter vibration. (Fourth example)

[0039] The numerical control device 100 according to a fourth embodiment has a frequency analysis function that adjusts the variable frequency rate RVF and the variable amplitude rate RVA while comparing the regenerative chatter vibration with a predetermined threshold, and calculates the variable frequency rate RVF and the variable amplitude rate RVA to reduce the regenerative chatter vibration to the predetermined threshold and prevent the spindle temperature from exceeding the temperature threshold T th exceeds.

[0040] Fig. Figure 6 shows a block diagram of the numerical control device 100 according to the fourth embodiment. The numerical control device 100 of the fourth embodiment includes a detection unit 15 for regenerative chatter vibration. The configuration of the numerical control device 100 according to the fourth embodiment is largely the same as that of the numerical control device according to the third embodiment, so only the different functions in the configuration are described.

[0041] The variation condition acquisition unit 10 attains a chatter vibration threshold K th (or a formula for calculating the chatter vibration threshold K) th ) in addition to an initial value of the variable amplitude rate RVA init , a variable frequency rate initial value RVF init , a temperature threshold T th , a variable amplitude rate slope RVA coefand a variable frequency rate slope RVF coef .

[0042] The variation magnification calculation unit 14 compares the spindle temperature with the temperature threshold T. th and decreases when the spindle temperature is greater than or equal to the temperature threshold T th The variable frequency rate (RVF) or the variable amplitude rate (RVA), or both, is gradually reduced. The method for gradual reduction is the same as that of the third embodiment and is therefore not described here.

[0043] The regenerative chatter vibration detection unit 15 is configured to detect regenerative chatter vibrations. The regenerative chatter vibration can be detected, for example, by a method (1) that performs a spectral analysis on a signal such as a cutting force, offset, cutting noise, and an electric current; a method (2) that obtains a root mean square of the signal described above; and a method (3) that employs machine learning, such as deep learning.

[0044] Fig. Figure 7 shows an example of frequency spectra. The regenerative chatter vibration detection unit 15 performs a Fourier transform of the spindle vibrations to obtain frequency spectra. Fig. Figure 7 indicates the horizontal axis with frequencies, and the vertical axis with the spectra of the amplitudes corresponding to the frequencies. The vibrations of a machine during cutting contain a complex mixture of many frequencies. A frequency analysis shows that the frequency component of the tool's cutting edge and its harmonic component are strongly pronounced. The frequency of the harmonic component is an integer multiple of the cutting edge's frequency component. The regenerative chatter detection unit 15 identifies strong vibrations not caused by the cutting edge and its harmonics as regenerative chatter vibrations.

[0045] The method for obtaining the root mean square (RMS) value of a signal obtains the root mean square of the signal described above over a time domain in order to calculate the RMS value of the signal. The magnitude of the RMS value can then be determined to detect the occurrence of regenerative chatter oscillations.

[0046] The method using deep learning creates a learning model that extracts the features of regenerative chatter oscillations from an input signal and uses the learning model to capture a regenerative chatter signal generated in the input signal.

[0047] The variation magnification calculation unit 14 determines the variable frequency rate RVF and the variable amplitude rate RVA to maintain the regenerative chatter signal at an acceptable level. In the above-described method for obtaining the root mean square (RMS) value, the variable frequency rate RVF and the variable amplitude rate RVA are determined such that the RMS value of the signal is less than or equal to the predetermined threshold. For example, in the deep learning method, a learning model is used to determine whether the regenerative chatter signal is maintained at an acceptable level.

[0048] In the method using spectral analysis, the amplitude of a regenerative chatter oscillation obtained by the Fourier transform is compared with the chatter oscillation threshold K. th compared. The chatter vibration threshold K threpresents a permissible limit for regenerative chatter vibration. The chatter vibration threshold K th is a limit value that does not affect the cutting process.

[0049] Here is an example of the chatter vibration threshold K. th This example provides a calculation formula for the chatter vibration threshold K. th defined. In the calculation formula, the chatter vibration threshold value K is th A coefficient multiple of the maximum amplitude of the harmonics at the cutting edge passing frequency. The variation magnification calculation unit 14 selects the maximum harmonic amplitude from the amplitude spectra and multiplies the selected maximum value by a given coefficient to determine the chatter vibration threshold K. th to calculate.

[0050] The variation magnification calculation unit 14 compares the chatter vibration threshold K.th with the amplitude of the regenerative chatter oscillation, and if the amplitude of the regenerative chatter oscillation is smaller than the chatter oscillation threshold K th If the variational magnification (one or both of the variable amplitude rate RVA and the variable frequency rate RVF) is reduced, the amplitude of the regenerative chatter oscillation gradually increases. The variational magnification calculation unit 14 stops the reduction of the variational magnification when the amplitude of the regenerative chatter oscillation exceeds the chatter oscillation threshold K. th reached.

[0051] The variable amplitude rate RVA at the time at which the amplitude exceeds the chatter oscillation threshold K th Once reached, it is used as the target value for the variable amplitude rate RVA. set denoted, and is the variable frequency rate RVF at the time when the amplitude reaches the threshold K thachieved, as the target value of the variable frequency rate RVF set designated.

[0052] The variation magnification calculation unit 14 sets the variation magnification to the target value and continues the cutting process, adjusting the spindle temperature according to the temperature threshold T. th compares. The variation magnification calculation unit 14 continues cutting when the spindle temperature is lower than the temperature threshold T. th The cutting process is interrupted, or stops, if the spindle temperature is greater than or equal to the temperature threshold T. th is.

[0053] The operation of the numerical control device 100 according to the fourth embodiment is described with reference to the text in Fig. The flowchart shown in Figure 8 describes a case in which regenerative chatter vibrations are detected by spectral analysis. The method for detecting regenerative chatter vibrations is not limited to spectral analysis.

[0054] First, the variation condition acquisition unit 10 obtains the variation conditions (step S21). Then, the spindle velocity calculation unit 11 calculates a spindle velocity (step S22). The initial variation increments are the initial value of the variable amplitude rate RVA. init and the initial value of the variable frequency rate RVF init , which are obtained by the variation condition acquisition unit 10.

[0055] An operator activates the numerical control device 100 to initiate the cutting process on the machine tool (step S23). The temperature acquisition unit 13 reaches the temperature of the spindle.

[0056] The variation magnification calculation unit 14 compares the spindle temperature with the temperature threshold T. th If the spindle temperature is lower than the temperature threshold T th If (step S24: No), the variation magnification calculation unit 14 continues cutting without changing the variation magnification (step S25). If the spindle temperature is greater than or equal to the temperature threshold T th If (step S24: Yes), the variation magnification calculation unit 14 reduces the variation magnification (at least either the variable amplitude rate RVA or the variable frequency rate RVF) (step S26).

[0057] The variation magnification calculation unit 14 compares the amplitude of the regenerative chatter vibration with the chatter vibration threshold K. th If the amplitude of the regenerative chatter oscillation is smaller than the chatter oscillation threshold Kth If (step S27: No), the variation magnification calculation unit 14 goes to step S26 and reduces the variation magnification. The variation magnification calculation unit 14 reduces the variation magnification as long as the amplitude of the regenerative chatter oscillation is below the chatter oscillation threshold K. th does not exceed the threshold value. If the amplitude of the regenerative chatter oscillation is greater than or equal to the chatter oscillation threshold K, the regenerative chatter oscillation threshold is not exceeded. th If (step S27: Yes) is, the variation magnification calculation unit 14 sets the variation magnification within the range that defines the chatter vibration threshold K. th does not exceed the target value of the variation magnification (target value of the variable amplitude rate RVA). set and target value of the variable frequency rate RVF set ).

[0058] The variation magnification calculation unit 14 compares the spindle temperature with the temperature threshold T.th If the spindle temperature is greater than or equal to the temperature threshold T th If (step S28: Yes), the variation magnification calculation unit 14 interrupts the cutting (step S29). If the spindle temperature is lower than the temperature threshold T th If (step S28: No), the variation magnification calculation unit 14 continues the cutting (step S30).

[0059] Fig. Figure 9 shows the changes in the variable amplitude rate RVA and the variable frequency rate RVF in the fourth embodiment. First, a spindle speed Ω is determined based on the initial value of the variable amplitude rate RVA. init and the initial value of the variable frequency rate RVF init calculated. If the spindle temperature, at the time the spindle speed is based on the initial value of the variable amplitude rate RVA. init and the initial value of the variable frequency rate RVFinit The temperature threshold T is varied. th The variation magnification calculation unit 14 reduces the variation magnification. The variation magnification can be reduced by a method (1) that reduces the variable frequency rate RVF by a variable frequency rate slope RVF. coef reduced by a method (2) that increases the variable amplitude rate RVA by a variable amplitude rate slope RVA coef reduced, or by a process (3) that performs both process (1) and process (2).

[0060] As the variation magnification decreases, the amplitude of the regenerative chatter oscillation gradually increases, assuming that time t' is the time at which the amplitude of the regenerative chatter oscillation exceeds the chatter oscillation threshold K. thIf the variable frequency rate (RVF) and the variable amplitude rate (RVA) are exceeded, they are set to the target value of the variable frequency rate (RVF). set or the target value of the variable amplitude rate RVA set determined.

[0061] The variation magnification calculation unit 14 determines whether the spindle temperature exceeds the temperature threshold T. th exceeds the target value of the variable frequency rate RVF when cutting with the setpoint set and the target value of the variable amplitude rate RVA set The process is carried out. Depending on the test result, cutting continues when the spindle temperature exceeds the temperature threshold T. th does not exceed the temperature threshold T, or the cutting process will be interrupted if the spindle temperature exceeds the temperature threshold T. th exceeds.

[0062] The numerical control device 100 of the fourth embodiment enables the automatic search for the variable amplitude rate RVA and the variable frequency rate RVF, which can keep the regenerative chatter vibration at an acceptable level and keep the temperature of the spindle at an acceptable level. (Fifth example)

[0063] The numerical control device 100 according to a fifth embodiment stores a variation magnification which is calculated by the variation magnification calculation unit 14 in association with blocks of the machine processing program. Fig. Figure 10 shows a block diagram of the numerical control device 100 according to the fifth embodiment. The numerical control device 100 of the fifth embodiment includes a variation magnification storage unit 16, which stores the blocks in the machining program in association with variation magnifications (variable amplitude rate and variable frequency rate). The configuration of the numerical control device according to the fifth embodiment is largely the same as that of the numerical control device 100 according to the first embodiment, and therefore only the different functions in the configuration are discussed. The functions of the variation magnification storage unit 16 can be applied to the numerical control device 100 according to the second to fourth embodiments and the sixth embodiment.

[0064] According to the numerical control device 100 of the fifth embodiment, the blocks in the machining program are stored in association with the variation magnifications, so that the variation magnification previously calculated during the execution of the relevant machining program can be used. This eliminates the need for subsequent adjustment of the variation magnification and reduces the physical load on the spindle and the computational load required to adjust the spindle speed. (Sixth embodiment example)

[0065] The numerical control device 100 according to a sixth embodiment displays variations during and after interruption of cutting, as well as changes in spindle temperature, and resets the variation and restarts cutting when the spindle has cooled to a predefined setpoint.

[0066] Fig. Figure 11 shows a block diagram of the numerical control device 100 according to the sixth embodiment. The numerical control device 100 of the sixth embodiment includes a display control unit 17. The configuration of the numerical control device 100 according to the sixth embodiment is largely the same as that of the numerical control device 100 according to the first embodiment, so only the different functions in the configuration are described. The functions of the numerical control device 100 of the sixth embodiment can be applied as post-cutting functions to the numerical control device 100 according to the first to fifth embodiments.

[0067] The display control unit 17 is configured to display at least the variable amplitude rates RVA, the variable frequency rates RVF, and the spindle temperatures on a display unit 70, both during and after cutting interruption, using a graph and numerical values. The variable amplitude rate RVA, the variable frequency rate RVF, and the spindle temperature can be displayed on the display unit 70 before cutting is interrupted.

[0068] The variation magnification calculation unit 14 compares the spindle temperature after the cutting is interrupted with a predefined setpoint and, when the spindle temperature has cooled to the setpoint, sets the variable amplitude rate RVA and the variable frequency rate RVF to the initial value of the variable amplitude rate RVA when the cutting is interrupted. init and the initial value of the variable frequency rate RVF init back.

[0069] The operation of the numerical control device 100 of the sixth embodiment is described with reference to the one in Fig. The flowchart shown in section 12 is described.

[0070] If the spindle temperature exceeds the temperature threshold T th If the setpoint is exceeded, the variation magnification calculation unit 14 interrupts the cutting process (step S31). After the cutting process is interrupted, the variation magnification calculation unit 14 obtains the spindle temperature to determine whether the spindle temperature is equal to or lower than the predefined setpoint. If the spindle temperature is higher than the predefined setpoint (step S32: No), the variation magnification calculation unit 14 waits a predetermined time (step S33) and then compares the spindle temperature with the predefined setpoint.

[0071] If the spindle temperature is equal to or lower than the predefined setpoint (step S32: Yes), the variation magnification calculation unit 14 sets the variable amplitude rate RVA and the variable frequency rate RVF to the initial value of the variable amplitude rate RVA when cutting is interrupted. init and the initial value of the variable frequency rate RVF init Back (step S34). The variation magnification calculation unit 14 restarts the cutting process with the initial value of the variable amplitude rate RVA. init and the initial value of the variable frequency rate RVF init , which were thus reset (step S35).

[0072] After the cutting process is interrupted, the display control unit 17 shows the graph and numerical values ​​of the variable amplitude rate RVA, the variable frequency rate RVF and the spindle temperature on the display unit 70. Fig. Figure 13 shows an example of a display screen showing the changes in the variable amplitude rate (RVA), variable frequency rate (RVF), and spindle temperature when the cutting interruption and restart are repeated. The variable amplitude rate (RVA) and variable frequency rate (RVF) gradually decrease, and the current variable amplitude rate (RVA) is 0.16 and the variable frequency rate (RVF) is 0.10. The spindle temperature also decreases with the changes in the variable amplitude rate (RVA) and variable frequency rate (RVF), so that the current spindle temperature is 121 degrees Celsius. The spindle temperature exceeds the temperature threshold T. th , so the variation conditions need to be reset.

[0073] This display screen is an example of the display screen according to the second embodiment. The display screen shows the minimum value of the variable amplitude rate RVA. min and the minimum value of the variable frequency rate RVF min The display screen according to the third embodiment can show the variable amplitude rate slope RVA. coef and the variable frequency rate slope RVF coef The display screen according to the fourth embodiment can display the frequency components of the regenerative chatter oscillation.

[0074] According to the numerical control device 100 of the sixth embodiment, after the cutting is interrupted, the variable amplitude rate RVA and the variable frequency rate RVF are reset to the initial value of the variable amplitude rate RVA. init and the initial value of the variable frequency rate RVF initreset. This allows the variation conditions to be set automatically.

[0075] Furthermore, in the numerical control device 100 of the sixth embodiment, the variable amplitude rate RVA, the variable frequency rate RVF, and the spindle temperature are displayed on the display unit 70 after the cutting process is interrupted. Although the values ​​of the variable amplitude rate RVA and the variable frequency rate RVF are controlled automatically, the values ​​associated with the control are displayed so that the operator can check the control status.

[0076] The following is a description of the hardware configuration of the numerical control device 100 that applies the present disclosure. Fig. Figure 14 shows a hardware configuration diagram of the numerical control device 100. As in Fig.As shown in Figure 14, the numerical control device 100 comprises a central processing unit (CPU) 111, configured to control the entire numerical control device 100, a read-only memory (ROM) 112, configured to store programs and data, and a random access memory (RAM) 113, onto which data is temporarily loaded. The CPU 111 reads a system program stored in the ROM 112 via a bus and executes a preventive action according to the system program to prevent the occurrence of regenerative chatter vibration.

[0077] A non-volatile memory 114 is, for example, buffered by a battery (not shown) so that the memory conditions can be maintained even if a power source of the numerical control device 100 is switched off. The non-volatile memory 114 is configured to store programs read from an external device 120 via interfaces 115, 118, and 119, and various data about inputs made and others entered via an input unit 30. The non-volatile memory 114 can store programs and data for implementing the numerical control device 100 of the illustrative embodiment. In addition, the display unit 70 is configured to display the various data, measurement results, factors for erroneous data, and the like.

[0078] Interface 115 is configured to connect the numerical control device 100 to the external device 120, such as an adapter. Programs, various parameters, and the like are read from the external device 120.

[0079] Interface 118 is configured to connect the numerical control device 100 to the display unit 70, such as a liquid crystal display. The display unit 70 shows, for example, data read into memory and data obtained as a result of program execution.

[0080] Interface 119 is configured to connect the numerical control device 100 to the input unit 30, such as a keyboard or a pointing device. The input unit 30 transmits commands, data, and other information generated by operator input via interface 119 to the CPU 111.

[0081] The present disclosure has been described in detail, but is not limited to the individual embodiments described above. Thus, various additions, substitutions, modifications, partial deletions, etc., can be made to these embodiments without deviating from the essence or core of the disclosure as it arises from the content of the appended claims and their equivalents. Furthermore, these embodiments can be realized by combining them. For example, the sequence of operations and the sequence of processes in these embodiments are given as examples and are therefore not limited to them.

[0082] Supplementary remarks on the embodiments of the present disclosure and their variations are described and presented below. (Supplementary Note 1)

[0083] A numerical control device (100) comprises: a variation condition acquisition unit (10) that acquires variation conditions for periodically varying a spindle speed; a spindle speed calculation unit (11) that calculates a vibrating spindle speed that varies periodically based on a variable amplitude rate and a variable frequency rate included in the variation conditions; a temperature acquisition unit (13) that acquires a temperature of a spindle; and a variation magnification calculation unit (14) that decreases one of the variable amplitude rates and the variable frequency rate, or both, when the temperature of the spindle exceeds a predefined temperature threshold. (Supplementary Note 2)

[0084] After reducing one or both of the variable amplitude rate and the variable frequency rate, the variation magnification calculation unit (14) interrupts cutting if the spindle temperature exceeds a predefined temperature threshold, or continues cutting if the spindle temperature does not exceed the predefined threshold. (Supplementary Note 3)

[0085] The variable amplitude rate is a coefficient of an amplitude of the spindle speed, and the variable frequency rate is a coefficient of a frequency of the spindle speed. (Supplementary Note 4)

[0086] The variation condition acquisition unit (10) acquires one or both of a minimum value of the variable amplitude rates and a minimum value of the variable frequency rate, and when the temperature of the spindle exceeds the predefined temperature threshold, the variation magnification calculation unit (14) decreases the minimum value of the variable amplitude rates or the minimum value of the variable frequency rate or decreases both of the minimum values. (Supplementary Note 5)

[0087] The variation condition acquisition unit (10) acquires one or both of a variable amplitude rate slope and a variable frequency rate slope, and when the temperature of the spindle exceeds the temperature threshold, the variation magnification calculation unit (14) reduces the variable amplitude rate by the variable amplitude rate slope or the variable frequency rate by the variable frequency rate slope or reduces both rates. (Supplementary Note 6)

[0088] The numerical control device (100) comprises a regenerative chatter oscillation detection unit (15) that detects a regenerative chatter oscillation, and the variation magnification calculation unit (14) reduces the variable amplitude rate or the variable frequency rate or both until the regenerative chatter oscillation drops to an acceptable level. (Supplementary Note 7)

[0089] The variation magnification calculation unit (14) continues cutting by maintaining the variable amplitude rate and the variable frequency rate at the time when the amplitude of the regenerative chatter oscillation reaches a predefined amplitude threshold, and interrupts cutting when the spindle temperature exceeds the predefined temperature threshold, or continues cutting when the spindle temperature does not exceed the predefined threshold. (Supplementary Note 8)

[0090] The numerical control device (100) comprises a variation magnification storage unit (16) which, in association with blocks in a machine processing program, stores the variable amplitude rate and the variable frequency rate, which are calculated by the variation magnification calculation unit (14) during the execution of the block. (Supplementary Note 9)

[0091] The variation magnification calculation unit (14) waits after the cutting is interrupted until the spindle temperature has dropped to a predefined setpoint, then resets the variable amplitude rate and the variable frequency rate to their respective initial values ​​when the cutting is interrupted and restarts the cutting. (Supplementary Note 10)

[0092] The numerical control device (100) includes a display control unit (17) which displays changes in the variable amplitude rate and the variable frequency rate on a display unit. (Supplementary Note 11)

[0093] A computer-readable storage medium (112, 113, 114) stores instructions that enable one or more processors (111) to: obtain variation conditions for periodically varying a spindle speed; calculate the periodically varying spindle speed based on a variable amplitude rate and a variable frequency rate included in the variation conditions; determine the temperature of a spindle; and decrease at least one of the variable amplitude rate and the variable frequency rate, or both, when the temperature of the spindle exceeds a predefined temperature threshold. Reference symbol list 100 Numerical control device 10 Variation Condition Acquisition Unit 11 Spindle speed calculation unit 12 Spindle motor control unit 13 Temperature acquisition unit 14 Variation magnification calculation unit 15 Detection unit for regenerative chatter vibration 16 variation magnification storage units 17 Display control unit 11 CPU 112 ROM 113 RAM 114 Non-volatile memory

Claims

[1] Numerical control device comprising: a variation condition acquisition unit that acquires variation conditions for periodically varying a spindle speed; a spindle velocity calculation unit that calculates a periodically varying vibration velocity of the spindle based on a variable amplitude rate and a variable frequency rate, which are included in the variation conditions; a temperature acquisition unit that achieves the temperature of a spindle; and A variation magnification calculation unit that reduces one or both of the variable amplitude rate and the variable frequency rate when the spindle temperature exceeds a predefined temperature threshold. [2] Numerical control device according to claim 1, wherein the variation magnification calculation unit reduces the variable amplitude rate and / or the variable frequency rate and then interrupts the cutting when the temperature of the spindle exceeds the predefined temperature threshold, or continues the cutting when the temperature of the spindle does not exceed the predefined threshold. [3] Numerical control device according to claim 1, wherein the variable amplitude rate is a coefficient of an amplitude of the spindle speed and the variable frequency rate is a coefficient of a frequency of the spindle speed. [4] Numerical control device according to claim 1, wherein the variation condition acquisition unit acquires one or both of a minimum value of the variable amplitude rate and a minimum value of the variable frequency rate, and when the temperature of the spindle exceeds the predefined temperature threshold, the variation magnification calculation unit reduces the variable amplitude rate to its minimum value or reduces the variable frequency rate to its minimum value or reduces both rates to their minimum values. [5] Numerical control device according to claim 1, wherein the variation condition acquisition unit acquires one or both of a variable amplitude rate slope and a variable frequency rate slope, and when the temperature of the spindle exceeds the predefined temperature threshold, the variation magnification calculation unit reduces the variable amplitude rate by the variable amplitude rate slope or reduces the variable frequency rate by the variable frequency rate slope or reduces both rates. [6] Numerical control device according to claim 1, comprising a regenerative chatter oscillation detection unit which detects a regenerative chatter oscillation, wherein the variation magnification calculation unit reduces one or both of the variable amplitude rate and the variable frequency rate until the regenerative chatter oscillation drops to an acceptable level. [7] Numerical control device according to claim 6, wherein the variation magnification calculation unit continues cutting by maintaining the variable amplitude rate and the variable frequency rate at the time when the amplitude of the regenerative chatter oscillation reaches a predefined amplitude threshold and interrupts cutting when the temperature of the spindle exceeds the predefined temperature threshold, or continues cutting when the temperature of the spindle does not exceed the predefined threshold. [8] Numerical control device according to claim 1, comprising a variation magnification storage unit which, in association with blocks of a machine processing program, stores the variable amplitude rate and the variable frequency rate which are calculated by the variation magnification calculation unit during the execution of the blocks. [9] Numerical control device according to claim 2, wherein the variation magnification calculation unit waits after interrupting the cutting until the temperature of the spindle drops to a predefined setpoint, and then resets the variable amplitude rate and the variable frequency rate to their respective initial values ​​upon interruption of the cutting in order to restart the cutting. [10] Numerical control device according to claim 9, comprising a display control unit that displays changes in the variable amplitude rate and the variable frequency rate on a display unit. [11] Computer-readable storage medium that stores instructions that enable one or more processors to: To obtain variation conditions for periodically varying a spindle speed; to calculate the spindle speed, which changes periodically, based on a variable amplitude rate and a variable frequency rate included in the variation conditions; to measure the temperature of a spindle; and to reduce at least one of the variable amplitude rate and variable frequency rate, or both, if the spindle temperature exceeds a predefined temperature threshold.

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