JP6984790B1 - Numerical control device and numerical control method - Google Patents

Abstract

A numerical control device that controls the relative vibration of the tool and the object to be machined. The phase difference between the spindle processing unit that detects changes in the spindle rotation speed and the vibration receding position with respect to the vibration advancing position is It is equipped with a phase difference calculation unit for calculating and a vibration amplitude calculation unit for calculating the vibration amplitude which is the difference between the vibration forward position and the vibration backward position, and the spindle processing unit detects a change in the spindle rotation speed during execution of the command block. In this case, the phase difference calculation unit recalculates the phase difference that suppresses the fluctuation of the vibration amplitude due to the change in the spindle rotation speed, and the vibration amplitude calculation unit changes the vibration amplitude based on the recalculated phase difference. It is a feature.

Description

The present disclosure relates to a numerical control device and a numerical control method.

When machining a workpiece with a machine tool, there is a method of dividing chips by relatively vibrating the cutting tool and the workpiece in the machining feed direction. Patent Document 1 describes the time delay of the vibration retreat position with respect to the vibration advance position generated based on the command block in the machining program from the ratio of the vibration amplitude specified at the time of movement and the feed rate of the tool to the work. A numerical control device having a means for calculating as a phase difference and generating a vibration forward position and a vibration backward position as a movement path for each drive axis based on the phase difference is disclosed.

Japanese Patent No. 5745710

However, in the technical matter described in Patent Document 1, since the phase difference of the vibration retreat position with respect to the vibration advance position is created in the command block unit, when the spindle rotation speed of the vibration cutting fluctuates during the execution of the command block (for example). , When the ratio to the command value is changed by constant peripheral speed control or spindle override), the phase difference error due to the change cannot be corrected. As a result, there are problems that the vibration conditions are not set appropriately, the chips are insufficiently divided, and an excessive load is applied to machine tool parts (ball screws, etc.), servomotors, and cutting tools.

The present disclosure dynamically follows the vibration conditions of vibration cutting even when the spindle rotation speed changes, prevents chip fragmentation defects, and processes under a wide range of conditions within the load that machine tools and cutting tools can withstand. It is an object of the present invention to provide a numerical control device and a numerical control method that enable the above.

In order to solve the above-mentioned problems, the numerical control device according to the present disclosure is a numerical control device that controls the relative vibration of the tool and the machining target, and includes a spindle processing unit that detects a change in the spindle rotation speed. , A phase difference calculation unit that calculates the phase difference that is the time delay of the vibration retreat position with respect to the vibration advance position, a vibration amplitude calculation unit that calculates the vibration amplitude that is the difference between the vibration advance position and the vibration retreat position, and a command block. It is equipped with a vibration frequency calculation unit that calculates the vibration frequency from the spindle rotation speed and the number of vibrations per rotation of the spindle during execution. The phase difference calculation unit recalculates the phase difference that suppresses the fluctuation of the vibration amplitude due to the change in the spindle rotation speed, the vibration frequency calculation unit calculates the vibration attenuation based on the vibration frequency, and the vibration amplitude calculation unit recalculates. When the vibration amplitude is changed based on the phase difference, the vibration amplitude is changed so as to suppress the amplitude attenuation .

The numerical control device according to the present disclosure dynamically follows the vibration conditions of vibration cutting even when the spindle rotation speed changes, prevents chip cutting defects, and within a load that a machine tool and a cutting tool can withstand. Processing under a wide range of conditions is possible.

It is a block diagram which shows an example of the structure of the numerical control apparatus which concerns on Embodiment 1. FIG. It is a figure which shows typically the structure of the shaft of the machine tool which concerns on Embodiment 1. FIG. It is a figure which shows an example of the machining program which concerns on Embodiment 1. FIG. It is a figure which shows the example of the vibration waveform calculated by the interpolation processing part which concerns on Embodiment 1. FIG. It is a figure which shows typically the relationship between the vibration forward position R1 and the vibration backward position R2 which concerns on Embodiment 1. FIG. It is a figure which shows the example of the vibration waveform calculated by the interpolation processing part in the prior art. It is a flowchart which shows the procedure of resetting the vibration condition which concerns on Embodiment 1. It is a block diagram which shows an example of the structure of the numerical control apparatus which concerns on Embodiment 2. FIG. It is a figure which shows typically the structure of the shaft of the machine tool which concerns on Embodiment 2. It is a figure which shows typically the change of the vibration frequency which concerns on Embodiment 2. It is a flowchart which shows the procedure of resetting the vibration condition which concerns on Embodiment 2. It is a figure which showed the relationship between the movement amount of the feed shaft and the vibration waveform which concerns on Embodiment 3. FIG. It is a flowchart explaining the procedure of resetting the vibration condition in Embodiment 3. It is a hardware configuration example of the control calculation unit which concerns on Embodiments 1 to 3. It is a hardware configuration example of the control calculation unit which concerns on Embodiments 1 to 3.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are designated by the same reference numerals. Duplicate descriptions will be simplified or omitted as appropriate. The present disclosure is not limited to the embodiments described below. Further, in the drawings shown below, the scale may differ from the actual scale, but the content of the present disclosure is not limited accordingly.

Embodiment 1.
FIG. 1 is a block diagram showing an example of the configuration of the numerical control device 1 of the present disclosure. The numerical control device 1 includes a drive unit 10, an input operation unit 20, a display unit 30, and a control calculation unit 40.

The drive unit 10 is a mechanism for driving one or both of the machining target and the tool in at least two axial directions. It has an X-axis servomotor 12 and a Z-axis servomotor 13 for moving a machining target and / or a tool in the X-axis and Z-axis directions defined on the numerical control device 1, respectively. Further, the X-axis servo control unit 15 and the Z-axis servo that control the position and speed of the machining target and / or the tool in the respective axial directions based on the positions and speeds of the X-axis servomotor 12 and the Z-axis servomotor 13. It has a control unit 16. Further, it has a spindle motor 11 for rotating the spindle for fixing the machining target, and a spindle servo control unit 14 for controlling the position of the spindle motor 11 and the rotation of the spindle for fixing the machining target. In this disclosure, only two axes, X-axis and Z-axis, are illustrated for the sake of simplicity, but the present invention is not limited to this, and three or more axes and a plurality of systems (for example, X1, X2, etc.) for each axis are shown. It may be a numerical control device that controls (・ ・).

FIG. 2 is a diagram schematically showing the configuration of the shaft of the machine tool 110 according to the first embodiment. The machine tool 110 is controlled by the numerical control device 1. The tool post 51 to which the cutting tool 50 of the machine tool 110 is attached is controlled to move in the X-axis and Z-axis directions by the X-axis servomotor 12 and the Z-axis servomotor 13 of the numerical control device 1, respectively. The machining target 60 is fixed to the headstock 70, and the position and rotation of the headstock 70 are controlled by the spindle motor 11. The processing target 60 rotates on the headstock 70 around the rotation shaft 71 of the headstock 70.

In FIG. 2, with the headstock 70 rotating around the rotation shaft 71, the cutting tool 50 moves along the movement path 52 and cuts the side surface of the machining target 60. However, the vibration on the feed axis side (X-axis or Z-axis) is not expressed in the movement path 52 in the figure. In the following description, vibration cutting will be described assuming that the feed shaft side (tool side) is vibrated. However, the present invention is not limited to this, as long as the tool and the machining target 60 vibrate relatively, the spindle side may be vibrated.

The input operation unit 20 is composed of input means such as a keyboard, buttons, and a mouse, and a user inputs commands to the numerical control device 1 or inputs a machining program or parameters. The display unit 30 is configured by a display means such as a liquid crystal display device, and displays information processed by the control calculation unit 40.

The control calculation unit 40 includes an input control unit 41, a data setting unit 42, a storage unit 43, a screen processing unit 44, an analysis processing unit 45, an interpolation processing unit 46, a spindle processing unit 47, and acceleration / deceleration processing. It has a unit 48 and an axis data output unit 49.

The input control unit 41 receives information input from the input operation unit 20. The data setting unit 42 stores the information received by the input control unit 41 in the storage unit 43. For example, when the input content is an edit of the machining program 432, the edited content is reflected in the machining program 432 stored in the storage unit 43, and when a parameter is input, the parameter of the storage unit 43 is reflected. It is stored in the storage area of 431.

The storage unit 43 stores information such as parameters 431 used in the processing of the control calculation unit 40, the machining program 432 to be executed, and screen display data 433 to be displayed on the display unit 30. Further, the storage unit 43 is provided with a shared area 434 for storing temporarily used data other than the parameter 431 and the machining program 432. The screen processing unit 44 controls the display unit 30 to display the screen display data of the storage unit 43.

The analysis processing unit 45 includes a movement command analysis unit 451 and a vibration command analysis unit 452. The movement command analysis unit 451 reads a machining program 432 including one or more command blocks (or simply referred to as blocks) stored in the storage unit 43, analyzes the read machining program 432 for each block, and commands. Generates movement commands such as movement, rotation, and speed of the axes included in the block. The vibration command analysis unit 452 analyzes whether the machining program 432 includes a vibration command, and if the vibration command is included, generates vibration conditions such as the vibration frequency and the vibration amplitude included in the vibration command. The interpolation processing unit 46 and the spindle processing unit 47 acquire the movement command and the vibration command analyzed by the analysis processing unit 45.

FIG. 3 is a diagram showing an example of a machining program 432. The machining program 432 is read line by line (command block), the movement command and vibration command are analyzed by the analysis processing unit 45, and the driving and vibration of each axis based on each command is executed by the interpolation processing unit 46 described later. .. Each block in the illustrated machining program means performing spindle speed command, positioning, oscillating cutting, and turning. Each block contains a command to be executed. For example, the F command included in "G1Z-10.F0.1" indicates the amount of movement of the feed axis (X-axis or Z-axis) with respect to one rotation of the spindle. In the case of F0.1, the feed shaft is moved at a speed of 0.1 mm / rev. Vibration cutting is performed based on the movement command and vibration command included in such a command block.

The interpolation processing unit 46 includes a phase difference calculation unit 462, a vibration amplitude calculation unit 463, a vibration frequency calculation unit 464, a vibration movement amount calculation unit 465, and a movement amount synthesis unit 466.

The function of the interpolation processing unit 46 will be described with reference to FIG. FIG. 4 is a diagram showing an example of a vibration waveform calculated by the interpolation processing unit 46. FIG. 4A is a diagram showing a change over time in the spindle rotation speed. It is shown that the vibration cutting is started by the execution of the command block at a certain time t0, and the spindle rotation speed increases at the time t2. Such a change in the spindle rotation speed is detected by the spindle processing unit 47, which will be described later, and is provided to the interpolation processing unit 46.

FIG. 4B is a diagram showing the relationship between the vibration forward position R1 and the vibration backward position R2. The vertical axis indicates the amount of movement of the feed axis (X-axis or Z-axis). The vibration receding position R2 starts moving with a time delay of t1-t0 with respect to the vibration forward position R1. The phase difference calculation unit 462 calculates the phase difference (W and W'in the figure) which is a time delay of t1-t0 of the vibration receding position R2 with respect to the vibration advancing position R1. As will be described later, the phase difference calculation unit 462 recalculates the phase difference W according to the change in the spindle rotation speed during the execution of the command block. Two types of paths, the vibration forward position R1 and the vibration backward position R2, are created using the calculated phase difference based on the vibration conditions and the processing conditions.

The vibration amplitude calculation unit 463 calculates the vibration amplitude, which is the difference between the movement amounts of the vibration forward position R1 and the vibration backward position R2 in each time from the start to the completion of the command block. FIG. 4C shows the temporal change of the vibration amplitude until the process started at time t0 ends at time t4.

The vibration frequency calculation unit 464 calculates the vibration frequency from the number of vibrations per rotation of the spindle and the rotation speed of the spindle. FIG. 5 is a diagram schematically showing the relationship between the vibration forward position R1 and the vibration backward position R2. R3 in FIG. 5 shows the movement path of one axis (X-axis or Z-axis) of the feed axis, and the straight line connecting the peak positions of this movement path R3 connects the vibration forward position R1 and the valley position. The straight line is the vibration retreat position R2. The vibration amplitude A, which is the difference between the vibration forward position R1 and the vibration backward position R2, the feed amount F of the feed shaft per rotation of the spindle, and the required time T per rotation of the spindle are represented by the relationships shown in the figure. Assuming that the number of vibrations per rotation of the spindle is 3.5 times and the rotation speed of the spindle is 6000 r / min as illustrated in FIG. 5, the vibration frequency is calculated as 350 Hz.

The vibration movement amount calculation unit 465 calculates the vibration movement amount by multiplying the difference between the vibration forward position R1 and the vibration backward position R2 at each time by the vibration waveform (FIG. 4 (d)). The movement amount synthesis unit 466 calculates the combined movement amount by combining the command movement amount and the vibration movement amount analyzed for each block (FIG. 4 (e)).

The spindle processing unit 47 has a spindle rotation command creation unit 471 and a spindle rotation speed calculation unit 472. The spindle rotation command creation unit 471 calculates the rotation speed to be commanded to the spindle motor 11 based on the machining program 432, and outputs the rotation speed command to the shaft data output unit 49. The spindle rotation speed calculation unit 472 acquires the phase of the spindle motor 11 from a detector (for example, an encoder) attached to the spindle motor 11 (not shown), and calculates the spindle rotation speed. Alternatively, the spindle rotation speed may be calculated based on the signal fed back from the spindle servo control unit 14. The spindle processing unit 47 monitors the spindle rotation speed while the command block is being executed, and detects a change in the spindle rotation speed. For example, the spindle rotation speed calculation unit 472 continuously calculates the spindle rotation speed while the command block is being executed, so that the spindle processing unit 47 detects a change in the spindle rotation speed. Further, the spindle processing unit 47 transmits the continuously calculated spindle rotation speed to the sequential interpolation processing unit 46 side.

The acceleration / deceleration processing unit 48 converts the combined movement amount of each drive shaft output from the interpolation processing unit 46 into a movement command per unit time considering acceleration / deceleration according to a predetermined acceleration / deceleration pattern. The axis data output unit 49 outputs the spindle rotation command, the movement command of the feed shaft processed by the acceleration / deceleration processing unit 48, and the vibration command to each axis of the drive unit 10.

Here, the reason for recalculating the phase difference W will be described. Since the vibration amplitude feed ratio Q defined in the machining program 432 is the ratio between the vibration amplitude A and the feed amount F for each rotation of the spindle, it has the relationship of the following equation (1).
Q = A / F ... (1)

Assuming that the time required for one rotation of the spindle is T, the phase difference W, the vibration amplitude A, and the feed amount F for each rotation of the spindle are related to the following equation (2), and the phase difference from the equations (1) and (2). Equation (3) is shown for W.
A / W = F / T ... (2)
W = AT / F = QT ... (3)

In equation (3), when the required time T per spindle rotation changes with the change in the spindle rotation speed during block execution, the phase difference W increases or decreases depending on the required time T per spindle rotation. Is shown.

FIG. 6 is a diagram showing an example of a vibration waveform calculated by an interpolation processing unit in the prior art. In FIG. 4, the phase difference W is recalculated with respect to the increase in the spindle rotation speed, but in FIG. 6, the phase difference W is fixed as shown in FIG. 6 (b). When the spindle rotation speed increases during the execution of the command block by changing the ratio from the command value in constant peripheral speed control or spindle override, if the phase difference W is constant under the vibration conditions specified in the command block, As shown in FIGS. 6 (c) to 6 (e), the vibration amplitude, which is the difference between the vibration forward position R1 and the vibration backward position R2, increases before and after the change in the spindle rotation speed. Such fluctuations may result in excessive amplitude on machine tool parts and the like. On the contrary, if the phase difference W is fixed when the rotation speed of the spindle becomes slow, the vibration amplitude is insufficient and the chip division becomes insufficient, which may cause machining defects.

On the other hand, in FIG. 4, the phase difference W'after the change of the spindle rotation speed is recalculated in order to suppress the fluctuation of the vibration amplitude with respect to the change of the spindle rotation speed during the execution of the command block. By adjusting the path of the vibration retreat position R2 so as to suppress the fluctuation of the vibration amplitude based on the recalculated phase difference W', it is possible to solve the problem due to the excessive or too small vibration amplitude.

Further, the vibration amplitude component is passed through the position loop gain before actually driving the servomotor. The position loop gain plays the role of a low-pass filter, and amplitude attenuation occurs when the vibration frequency of the feed axis increases. Therefore, as a preferable additional configuration, the vibration frequency calculation unit 464 calculates the amplitude attenuation based on the vibration frequency. The vibration amplitude calculation unit 463 changes the vibration amplitude so as to suppress the amplitude attenuation when the vibration amplitude is changed based on the recalculated phase difference. By doing so, it is possible to alleviate the attenuation of the vibration amplitude with respect to the increase / decrease of the vibration frequency due to the fluctuation of the spindle rotation speed, and it is possible to solve the problem due to the excess or the excess of the vibration amplitude. Such suppression of vibration damping can also be combined in the embodiments described below.

Next, the procedure for resetting the vibration conditions in the first embodiment will be described with reference to the flowchart of FIG. The numerical control method of the numerical control device 1 in the present disclosure is shown by the procedure of the flowchart.

In step S101, the command block included in the machining program 432 is executed, and the vibration condition is set. In step S102, spindle rotation and machining are started. In step S103, the spindle processing unit 47 detects whether or not there is a change in the spindle rotation speed. If a change in the spindle rotation speed is detected, the process proceeds to step S105. On the other hand, when there is no change in the spindle rotation speed, the vibration condition defined by the command block is maintained in step S104. On the other hand, in step S105, the phase difference calculation unit 462 recalculates the phase difference W that suppresses the fluctuation of the vibration amplitude A after the change in the spindle rotation speed. Here, in order to suppress the fluctuation of the vibration amplitude A, it is ideal that the vibration amplitude A before and after the change of the spindle rotation speed during the execution of the command block is constant, but it is not required to be a completely constant value. However, fluctuations due to various factors in actual machining such as the computing power of the control computing unit 40 and the machining program 432 are allowed. In step S106, the vibration amplitude A is changed by adjusting the movement path of the vibration retreat position R2 based on the recalculated phase difference W by the vibration amplitude calculation unit 463.

In step S107, it is determined whether or not the command block has ended, and if the command block has not ended, the process returns to the front of step S103, and the monitoring of the spindle rotation speed is repeated. If the command block is finished, the process is finished.

As described above, the numerical control device 1 according to the first embodiment is a numerical control device 1 that controls the relative vibration of the tool and the machining target 60, and includes a spindle processing unit 47 that detects a change in the spindle rotation speed. The phase difference calculation unit 462 that calculates the phase difference that is the time delay of the vibration retreat position with respect to the vibration advance position, and the vibration amplitude calculation unit 463 that calculates the vibration amplitude from the difference in the amount of movement between the vibration advance position and the vibration retreat position. When the spindle processing unit 47 detects a change in the spindle rotation speed during execution of the command block of the machining program, the phase difference calculation unit 462 re-resumes the phase difference that suppresses the fluctuation of the vibration amplitude due to the change in the spindle rotation speed. The vibration amplitude calculation unit 463 is configured to change the vibration amplitude based on the recalculated phase difference. With such a configuration, even when the spindle rotation speed changes, the vibration conditions of vibration cutting are dynamically followed, chip fragmentation defects are prevented, and machine tools and cutting tools can withstand a wide range of conditions. Can be processed.

Embodiment 2.
The numerical control device 1 according to the second embodiment is further provided with a vibration frequency changing unit 461. Although FIG. 8 is used for the description of the numerical control device 1 according to the second embodiment, the description of the configuration of each part that overlaps with the first embodiment will be omitted.

As described in the first embodiment, the vibration frequency of the vibration cutting is calculated from the spindle rotation speed and the number of vibrations per one rotation of the spindle. If the spindle rotation speed becomes high while the command block is being executed, the vibration frequency also becomes too high, which may give an excessive load to machine tool parts (ball screws, etc.), servomotors, and cutting tools. Therefore, the vibration frequency changing unit 461 dynamically changes the vibration frequency per spindle rotation in response to the change in the spindle rotation speed during the execution of the command block.

FIG. 9 is a diagram schematically showing the configuration of the shaft of the machine tool 110 according to the second embodiment. The figure shows an example in which end face machining is performed on the machining target 60 under constant peripheral speed control. With the headstock 70 rotating around the rotating shaft 71, the cutting tool 50 moves along the moving path 53 and cuts the end face of the machining target 60. In the case of constant peripheral speed control, the spindle rotation speed is controlled so that the peripheral speed becomes constant with respect to changes in the X-axis. The smaller the machining diameter (that is, the closer the X coordinate is to the center) during execution of the command block, the faster the spindle rotation speed, and the vibration frequency increases in proportion to the spindle rotation speed. It should be noted that the end face machining by constant peripheral speed control is shown as an example in which the vibration frequency fluctuates during the execution of the command block, and the present disclosure is not limited to such control.

The vibration frequency changing unit 461 compares the vibration frequency calculated by the vibration frequency calculation unit 464 with the threshold value of the set vibration frequency. The vibration frequency calculation unit 464 continuously calculates the vibration frequency during the execution of the command block, and the vibration frequency changing unit 461 monitors the fluctuation. When the calculated vibration frequency is outside the range of the vibration frequency range defined by the threshold value, the vibration frequency changing unit 461 changes the vibration frequency per spindle rotation currently set, and within the range of the vibration frequency range. , The machine tool 110 is controlled so that it can be operated.

FIG. 10 is a diagram schematically showing a change in the number of vibrations. FIG. 10A shows a situation in which the coordinates of the X-axis, which is the feed axis, decrease from 50 to 0 with the passage of time, and the cutting tool 50 advances the machining of the machining target 60 toward the rotary shaft 71 along the movement path 53. Is shown. FIG. 10B shows a change in the spindle rotation speed, and shows that the spindle rotation speed increases and reaches 4500 r / min and becomes constant as the X-axis position decreases. FIG. 10C shows the number of vibrations per rotation of the spindle set by the vibration frequency changing unit 461, and FIG. 10D shows the vibration frequency calculated by the vibration frequency calculation unit 464.

In vibration cutting, it is necessary that the number of vibrations per rotation of the spindle is not a natural number in order to efficiently divide chips, and the ideal number of vibrations is n + 0.5 (n = 0, 1, 2, ·) using n.・ ・). That is, n is 0 or a natural number. Efficiently dividing the chips does not mean that the chips have varying lengths, but that the chips are divided into short pieces on average. Further, if there is a deviation from n + 0.5, the length of the chips will vary slightly, but the deviation is allowed unless there is a substantial effect on processing. The substantial effect on the processing means that the chip is poorly divided and the length of the chip varies by, for example, about ± 50% or more.

In FIG. 10C, 3.5 times is set as an example of the initial value of the number of vibrations determined by the machining program 432. In FIG. 10D, 100 Hz is set as an example of the threshold value of the set vibration frequency. The set vibration frequency threshold value is stored in the storage unit 43 as a parameter 431. The threshold value of the vibration frequency set as the parameter 431 may be dynamically changed according to the feedback of the load of the machine tool or the cutting tool.

When the upper limit of the vibration frequency is 100 Hz, the allowable spindle rotation speeds at 3.5, 2.5, 1.5, and 0.5 vibrations of the feed shaft per rotation of the spindle are, respectively.
100 (Hz) x 60 (s) /3.5 (times / r) = 1714 (r / min)
100 (Hz) x 60 (s) /2.5 (times / r) = 2400 (r / min)
100 (Hz) x 60 (s) /1.5 (times / r) = 4000 (r / min)
100 (Hz) x 60 (s) /0.5 (times / r) = 12000 (r / min)
Will be. When the X-axis coordinate of the cutting tool 50 moves from 50 to 0 and the spindle rotation speed increases under constant peripheral speed control, when the spindle rotation speed exceeds 1714 r / min, it is the initial value of the vibration frequency. Since the threshold value of 100 Hz is exceeded at 3.5 times, the vibration frequency changing unit 461 changes the vibration frequency per spindle rotation from 3.5 times to 2.5 times during execution of the command block. As a result, the calculated vibration frequency is controlled in the vibration frequency region (100 Hz or less) determined by the threshold value. Although only the upper limit threshold value of the vibration frequency was set, a lower limit threshold value, for example, 10 Hz is set, and the calculated vibration frequency is within the range of the vibration frequency range determined by the threshold value (in this case, the lower limit threshold value is 10 Hz or more). It is also possible to control within the upper limit threshold value of 100 Hz).

The change in the number of vibrations increases or decreases the natural number from the initial value, but the number of vibrations that falls within the frequency range determined by the threshold value and minimizes the difference before and after the change is selected. For example, if the initial value of the number of vibrations is 3.5, and 2.5 times does not fall within the vibration frequency range determined by the threshold value, 1.5 times is selected as a candidate for the next number of vibrations. To.

Next, the procedure for resetting the vibration conditions in the second embodiment will be described with reference to the flowchart of FIG. The numerical control method of the numerical control device 1 in the present disclosure is shown by the procedure of the flowchart. In FIG. 11, duplicate description will be omitted for the same steps as in FIG. Since steps S201 to S206 are the same as steps S101 to S106, and steps S209 and S107 are the same, the description thereof will be omitted.

In step S207, the vibration frequency changing unit 461 compares the vibration frequency calculated by the vibration frequency calculation unit 464 with the set vibration frequency threshold, and the calculated vibration frequency is in the range of the vibration frequency region determined by the threshold. Determine if it is within. When the calculated vibration frequency is within the vibration frequency region, the number of vibrations is not changed and the process proceeds to step S209. On the other hand, when the calculated vibration frequency is out of the range, the process proceeds to step S208, and the calculated vibration frequency is changed to the number of vibrations within the range of the vibration frequency region during execution of the command block. The process proceeds to step S209 under the changed vibration conditions.

In addition, resonance may occur in a part of the frequency band of the vibration frequency region determined by the threshold value due to the mechanical structure of the machine tool or the like. In such a case, it is desirable to set to avoid the resonance frequency band in the vibration frequency region as a preferable additional configuration. In step S207, the vibration frequency changing unit 461 determines whether the calculated vibration frequency is within the range of the vibration frequency region determined by the threshold value, and also determines whether the calculated vibration frequency is included in the resonance frequency band. Even if the calculated vibration frequency is within the vibration frequency range, if it is included in the resonance frequency band, the vibration frequency is within the vibration frequency range and is not included in the resonance frequency band. Select the number of vibrations that minimizes the difference before and after the change.

In step S207, it is determined whether to change the vibration frequency based on the threshold value of the vibration frequency, but the length of the chips may be used as a criterion for changing the vibration frequency. The chip length L is the number of vibrations per rotation of the spindle K, and the machining diameter of the machining target 60 is r.
L = 2πr / K ... (4)
It is estimated by. When the end face of the machining target 60 is machined under the above-mentioned constant peripheral speed control, when the X-axis coordinate of the cutting tool 50 moves from 50 to 0, the chip length becomes smaller due to the decrease in the machining diameter r. If the chips become too small, problems such as clogging of the chips may occur in the chip conveyor or the like.

Therefore, instead of the set threshold value of the vibration frequency, the length of the chip can be used as the determination criterion in step S207. In this case, while the command block is being executed, a recognition means such as a camera for acquiring the length of chips generated by cutting is provided, and the vibration frequency changing unit 461 acquires information on the chip length from the recognition means and stores it. Compare with the chip length threshold set as parameter 431 stored in 43. If the length of the chips generated by the cutting is outside the range of the chip length determined by the threshold value, the process proceeds to step S208, and the vibration frequency changing unit 461 changes the vibration frequency during the execution of the command block. If the length of the chips generated by the cutting process is within the range of the chip length region determined by the threshold value, the number of vibrations is not changed and the process proceeds to step S209. As a result, the length of the chips is controlled to be within the range determined by the threshold value, the clogging of the chips in the chip conveyor, etc. is prevented, and the vibration conditions of the vibration cutting are dynamically followed, and the chips are divided. It prevents defects and enables machining under a wide range of conditions within the load that machine tools and cutting tools can withstand.

Further, instead of setting the threshold values of the vibration frequency and the chip length, it is also possible to set the threshold value of the load torque. In this case, the vibration frequency changing unit 461 is currently based on the motor drive current values obtained from the spindle servo control unit 14, the X-axis servo control unit 15, and the Z-axis servo control unit 16 of the drive unit 10 during command block execution. Calculate the load torque of. In step S207, the vibration frequency changing unit 461 compares the calculated load torque with the threshold value of the load torque set as the parameter 431 in the storage unit 43. When the calculated load torque is out of the range of the load torque determined by the threshold value, the process proceeds to step S208, and the vibration frequency changing unit 461 is the load torque whose load torque calculated during the execution of the command block is determined by the threshold value. Change the number of vibrations so that it is within the range of. If the calculated load torque is within the range of the load torque region determined by the threshold value, the number of vibrations is not changed and the process proceeds to step S209. This dynamically follows the vibration conditions of vibration cutting, prevents chip fragmentation defects, and enables machining under a wide range of conditions within the load that machine tools and cutting tools can withstand. Instead of calculating the load torque, a threshold value may be set for the motor drive current value, and the vibration frequency, the length of chips, and the load torque may be determined in step S207 as to the necessity of changing the number of vibrations.

In FIG. 11, the vibration frequency change unit 461 changes the vibration frequency (that is, steps S207 and S208) is executed after steps S205 and S206, but they may be executed in parallel. Further, after the vibration frequency change is executed in steps S207 and S208, the phase difference may be recalculated and the vibration amplitude A may be changed in steps S204 and S205. The vibration frequency, chip length, load torque, and motor drive current value were increased as the parameters 431 to be monitored while the command block was being executed by the vibration frequency changing unit 461 in step S207. At least one of these was monitored. It may be a target, and if a plurality of parameters 431 are combined and any one of the parameters is out of the range allowed by the threshold value, the vibration frequency may be changed. For example, if two parameters, the vibration frequency and the chip length, are monitored, the vibration frequency is within the range defined by the threshold value, but the chip length is outside the range defined by the threshold value. The number of vibrations is changed.

As described above, the numerical control device 1 according to the second embodiment further includes the vibration frequency changing unit 461, and the vibration frequency changing unit 461 is set to the vibration frequency calculated by the vibration frequency calculating unit 464 while the command block is being executed. If the calculated vibration frequency is outside the range determined by the threshold, the number of vibrations is changed so that it falls within the range determined by the threshold during command block execution. It is composed. With such a configuration, when the spindle rotation speed changes, the vibration conditions of vibration cutting are dynamically followed, chip fragmentation defects are prevented, and machine tools and cutting tools can withstand a wide range of conditions. Processing becomes possible.

Embodiment 3.
The numerical control device 1 according to the third embodiment has a configuration in which when the number of vibrations is changed, the vibration amplitude is corrected so as to provide a missed swing section of chips.

In the second embodiment, it has been described that the vibration frequency changing unit 461 is selected under the condition that n + 0.5 is satisfied by using n (n = 0, 1, 2, ...) As the vibration frequency after the change. However, 0.5 times was selected as a candidate for the number of vibrations in order to lower the vibration frequency, but if it cannot be kept within the range of the vibration frequency range determined by the threshold value even if it is changed, the number of vibrations satisfying the condition of n + 0.5. Cannot be selected. In such a case, it is permissible to select the number of vibrations, for example, n + 0.3, which is deviated from the ideal condition of n + 0.5.

FIG. 12 is a diagram showing the relationship between the movement amount of the feed shaft and the vibration waveform. The vertical axis is the amount of movement of the feed axis (X-axis or Z-axis), and the horizontal axis is the phase of the main axis. The solid line shows the vibration waveform of the feed shaft, and the broken line shows the vibration waveform of the feed shaft one rotation before the main shaft.

In order to efficiently divide chips by vibration cutting, by selecting n + 0.5 as the number of vibrations, the vibration cutting path of the Nth spindle (N is a natural number) and the vibration cutting path of the next N + 1th spindle The phase is shifted so that the vibration cutting path of the next spindle N + 1th rotation partially passes through the path cut at the Nth rotation of the spindle. As a result, a missed swing section in which chips are not generated is generated in the vibration cutting path of the N + 1th rotation of the spindle, and it becomes possible to process the chips while sequentially dividing them. In actual machining, the Nth rotation of the spindle may overlap not only with the next N + 1th rotation but also with subsequent rotations, for example, the N + 2nd rotation, which is limited to the case illustrated in FIG. I can't.

FIG. 12A shows a vibration waveform in which an ideal number of vibrations satisfying n + 0.5 is set. The movement path of the Nth rotation of the spindle and the movement path of the N + 1th rotation of the spindle partially overlap, and the missed swing section is formed. It is provided. On the other hand, FIG. 12B shows a vibration waveform in which the number of vibrations deviated from n + 0.5 is set, and a missed swing section in which the movement path of the Nth rotation of the spindle and the movement path of the N + 1th rotation of the spindle overlap is obtained. It is not possible to divide the chips sufficiently.

Therefore, as shown in FIG. 12 (c), when the number of vibrations deviated from n + 0.5 is set, the vibration amplitude is corrected so that a missed swing section occurs. When the vibration frequency changing unit 461 changes to a vibration frequency other than 0.5 plus 0 or a natural number, the vibration amplitude calculating unit 463 causes a missed swing section from the spindle phase and the movement path of each axis. Correct the vibration amplitude.

FIG. 13 is a flowchart illustrating a procedure for resetting the vibration condition in the third embodiment. The numerical control method of the numerical control device 1 in the present disclosure is shown by the procedure of the flowchart. In FIG. 13, duplicate description will be omitted for the same steps as in FIG. Since steps S301 to S306 are the same as steps S201 to S206, and steps S311 and S209 are the same, the description thereof will be omitted.

In step S307 of FIG. 13, it is determined whether the vibration frequency calculated by the vibration frequency calculation unit 464 is within the vibration frequency region determined by the threshold value. As described in the second embodiment, in addition to the vibration frequency, the chip length, the load torque, and the motor drive current can be used as parameters for determining the number of vibrations.

If the calculated vibration frequency is out of the range of the vibration frequency region determined by the threshold value in step S307, the process proceeds to step S308, and it is determined whether the change is possible with the ideal vibration frequency n + 0.5. Here, if it can be changed, in step S309, the number of vibrations satisfying the condition of the number of vibrations n + 0.5 is set. If the change cannot be made, the number of vibrations is changed under the condition that does not satisfy n + 0.5 in step S310, and the vibration amplitude A is corrected so that a missed swing section occurs. Even if there is a deviation from the ideal number of vibrations (for example, n + 0.3), only the change in the number of vibrations may be executed in step S310 if the missed swing section required for chip fragmentation can be obtained.

As described above, in the numerical control device 1 according to the third embodiment, when the vibration frequency changing unit 461 changes to a vibration frequency other than the number obtained by adding 0 or a natural number to 0.5, the vibration amplitude calculating unit 463 has a spindle phase. Based on the movement path of each axis, the vibration amplitude is corrected so that a missed swing section occurs. With such a configuration, when the spindle rotation speed changes, the vibration conditions of vibration cutting are dynamically followed, chip fragmentation defects are prevented, and machine tools and cutting tools can withstand a wide range of conditions. Processing becomes possible. Moreover, even if the number of vibrations deviates from the ideal condition, cutting of chips is efficiently executed.

Next, the hardware configuration of the control calculation unit 40 included in the numerical control device 1 will be described. FIG. 14 is a diagram showing a hardware configuration example of the control calculation unit 40 according to the first to third embodiments. The control calculation unit 40 can be realized by the processor 401 and the memory 402 shown in FIG. An example of the processor 401 is a CPU (Central Processing Unit, a central processing unit, a processing unit, a computing device, a microprocessor, a microcomputer, a processor (also referred to as a Digital Signal Processor)) or a system LSI (Large Scale Integration). An example of the memory 402 is a RAM (Random Access Memory) or a ROM (Read Only Memory).

The control calculation unit 40 is realized by the processor 401 reading and executing a program stored in the memory 402 for executing the operation of the control calculation unit 40. It can also be said that this program causes a computer to execute the procedure or method of the control calculation unit 40. The memory 402 is also used as a temporary memory when the processor 401 executes various processes.

The program executed by the processor 401 may be a computer program product having a computer-readable and non-transitory recording medium containing a plurality of instructions for performing data processing, which can be executed by a computer. .. The program executed by the processor 401 causes the computer to execute data processing by a plurality of instructions.

As shown in FIG. 15, the control calculation unit 40 may be realized by dedicated hardware (processing circuit 403). For example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Further, the functions of the control calculation unit 40 may be partially realized by dedicated hardware and partially realized by software or firmware.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations as long as it does not deviate from the gist of the present invention. It is also possible to omit or change the part.

1 Numerical control device, 10 Drive unit, 20 Input operation unit, 30 Display unit, 40 Control calculation unit, 11 Spindle motor, 12 X-axis servo motor, 13 Z-axis servo motor, 14 Spindle servo control unit, 15 X-axis servo control Unit, 16 Z-axis servo control unit, 41 input control unit, 42 data setting unit, 43 storage unit, 44 screen processing unit, 45 analysis processing unit, 46 interpolation processing unit, 47 spindle processing unit, 48 acceleration / deceleration processing unit, 49 Axis data output unit, 50 cutting tool, 51 turret, 60 machining target, 70 spindle, 71 rotary shaft, 401 processor, 402 memory, 403 processing circuit, 431 parameters, 432 machining programs, 433 screen display data, 434 shared area , 451 movement command analysis unit, 452 vibration command analysis unit, 461 vibration frequency change unit, 462 phase difference calculation unit, 463 vibration amplitude calculation unit, 464 vibration frequency calculation unit, 465 vibration movement amount calculation unit, 466 movement amount synthesis unit, 471 Spindle rotation command creation unit, 472 Spindle rotation speed calculation unit

Claims (13)

A numerical control device that controls the relative vibration of the tool and the object to be machined.
A spindle processing unit that detects changes in the spindle rotation speed,
A phase difference calculation unit that calculates the phase difference, which is the time delay of the vibration receding position with respect to the vibration advancing position,
A vibration amplitude calculation unit that calculates the vibration amplitude, which is the difference between the vibration forward position and the vibration backward position,
A vibration frequency calculation unit that calculates the vibration frequency from the spindle rotation speed and the number of vibrations per rotation of the spindle during execution of the command block.
Equipped with
If the spindle processing unit detects a change of spindle speed during the instruction block execution, the phase difference calculation unit recalculates the phase difference to suppress the variation of the vibration amplitude due to changes in the spindle rotation speed,
The vibration frequency calculation unit calculates the amplitude damping based on the vibration frequency, and calculates the amplitude damping.
The vibration amplitude calculation unit is a numerical control device characterized in that when the vibration amplitude is changed based on the recalculated phase difference, the vibration amplitude is changed so as to suppress the amplitude attenuation. The numerical control device according to claim 1, wherein the vibration amplitude calculation unit changes the vibration amplitude by adjusting the path of the vibration retreat position based on the recalculated phase difference. A numerical control device that controls the relative vibration of the tool and the object to be machined.
A vibration frequency changing unit that changes the vibration frequency per rotation of the spindle,
It is equipped with a vibration frequency calculation unit that continuously calculates the vibration frequency from the spindle rotation speed and the number of vibrations per rotation of the spindle during execution of the command block.
The vibration frequency changing unit compares the vibration frequency calculated by the vibration frequency calculation unit with the set vibration frequency threshold, and the calculated vibration frequency is outside the range of the vibration frequency range determined by the threshold. In some cases, a numerical control device characterized in that the number of vibrations is changed so as to be within a range determined by a threshold value during execution of the command block. The numerical control device according to claim 3, wherein the vibration frequency changing unit is changed to a vibration frequency within a range of a vibration frequency region determined by a threshold value and the difference before and after the change is minimized. When the calculated vibration frequency is within the vibration frequency region but is included in the resonance frequency band, the vibration frequency changing unit is a vibration frequency within the vibration frequency region and not included in the resonance frequency band. The numerical control device according to claim 3 or 4, wherein the number of times is changed. A numerical control device that controls the relative vibration of the tool and the object to be machined.
Equipped with a vibration frequency changing unit that changes the vibration frequency per rotation of the spindle.
In the vibration frequency changing unit, the length of the chips generated by the processing is determined by the threshold value based on the comparison between the length of the chips generated by the processing during the execution of the command block and the threshold value of the set chip length. A numerical control device comprising changing the number of vibrations so as to fall within a range determined by a threshold value during execution of the command block when the length is outside the range of the chip length. A numerical control device that controls the relative vibration of the tool and the object to be machined.
A vibration frequency changing unit that changes the vibration frequency per rotation of the spindle,
A drive unit that drives one or both of the machined object and the tool in at least two axial directions is provided.
The vibration frequency changing unit determines the load torque obtained from the drive unit by the threshold value based on the comparison between the load torque obtained from the drive unit during execution of the command block and the set load torque threshold value. A numerical control device comprising changing the number of vibrations so as to be within a range determined by a threshold value during execution of the command block when the load torque is outside the range to be applied. A numerical control device that controls the relative vibration of the tool and the object to be machined.
A vibration frequency changing unit that changes the vibration frequency per rotation of the spindle,
A drive unit that drives one or both of the machined object and the tool in at least two axial directions is provided.
The vibration frequency changing unit is the motor drive current obtained from the drive unit based on the comparison between the motor drive current value obtained from the drive unit and the threshold value of the set motor drive current value during execution of the command block. When the value is outside the range of the motor drive current value determined by the threshold value, the numerical control device is characterized in that the vibration frequency is changed so as to be within the range determined by the threshold value during the execution of the command block. The numerical control device according to any one of claims 3 to 8, wherein the vibration frequency changing unit changes the vibration frequency to a number obtained by adding 0 or a natural number to 0.5. When the vibration frequency changing unit is changed to a vibration frequency other than 0.5 plus 0 or a natural number, a missed swing section required for chip division is generated based on the spindle phase and the movement path of each axis. The numerical control device according to any one of claims 3 to 9, wherein the vibration amplitude is corrected. This is a numerical control device method that controls the relative vibration of the tool and the object to be machined.
Steps to detect changes in spindle speed during command block execution, and
The step of recalculating the phase difference that suppresses the fluctuation of the vibration amplitude due to the change of the spindle rotation speed, and
During the execution of the command block, a step of calculating the vibration frequency from the spindle rotation speed and the number of vibrations per spindle rotation, and
The step of calculating the amplitude damping based on the vibration frequency and
A numerical control method comprising a step of changing the vibration amplitude so as to suppress the amplitude attenuation when the vibration amplitude is changed based on the recalculated phase difference. A step of monitoring at least one of the parameters of vibration frequency, load torque, motor drive current value, and chip length generated by machining, which is acquired during command block execution.
A step of comparing the parameter to be monitored with the set threshold value of the parameter, and
Numerical value including, when the parameter to be monitored is outside the allowable range of the parameter determined by the threshold value, the step of changing the vibration frequency so as to be within the range determined by the threshold value during the execution of the command block. Control method. When changing the number of vibrations during the execution of the command block, a step of determining whether or not a missed swing section required for chip division occurs from the spindle phase and the movement path of each axis, and
The numerical control method according to claim 12 , further comprising a step of correcting the vibration amplitude so that the missed swing section occurs when the missed swing section required for chip fragmentation cannot be obtained.

Images