Control device of a machine tool

Abstract

Provided is a control device for a machine tool, which can quickly determine the frequency parameter and amplitude parameter of a desired swing command capable of chopping chips. The machine tool performs machining while relatively swinging a tool (T) with respect to a workpiece (W), and the control device (1) of the machine tool includes: a swing command calculation unit (113) that calculates a command for a swing motion; a first swing condition determination unit (111) that determines one of a frequency parameter composed of the frequency of the swing command or a frequency multiplier and an amplitude parameter composed of the amplitude of the swing command or an amplitude multiplier as a first swing condition; and a second swing condition calculation unit (112) that calculates the other of the frequency parameter and the amplitude parameter based on the first swing condition determined by the first swing condition determination unit (111) as a second swing condition.

Description

Technical Field

[0001] The present invention relates to a control device for a machine tool. Background Art

[0002] Conventionally, when machining a workpiece using a cutting tool, it has been known that continuously generated chips wrap around the cutting tool or the like, causing machining defects, intermittent stoppages, mechanical failures, etc. In response to this, a swing cutting method has been proposed in which the cutting tool and the workpiece are relatively swung while machining to break up the chips (for example, refer to Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-56515 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, in conventional swing cutting, regarding the frequency parameter (frequency or frequency magnification factor, the same applies hereinafter) and the amplitude parameter (amplitude or amplitude magnification factor, the same applies hereinafter) of the swing command, conditions are set and determined in order to break up the chips, so at present it takes time.

[0008] Therefore, in the control device of a machine tool that performs swing cutting, it is desired to quickly determine the frequency parameter and the amplitude parameter of a desired swing command that can break up the chips.

[0009] Means for Solving the Problems

[0010] (1) One aspect of the present disclosure is a control device for a machine tool that machines while relatively swinging a tool and a workpiece. The control device includes: a swing command calculation unit that calculates a command for a swing motion; a first swing condition determination unit that determines one of a frequency parameter composed of the frequency or frequency magnification factor of the swing command and an amplitude parameter composed of the amplitude or amplitude magnification factor of the swing command as a first swing condition; and a second swing condition calculation unit that calculates the other of the frequency parameter and the amplitude parameter as a second swing condition based on the first swing condition determined by the first swing condition determination unit.

[0011] Advantages of the Invention

[0012] According to the present disclosure, it is possible to provide a control device for a machine tool that can quickly determine the frequency parameter and the amplitude parameter of a desired swing command that can break up the chips by using the correlation between the frequency parameter and the amplitude parameter. Description of the Drawings

[0013] Figure 1 Indicates the machining of the embodiment of the present invention.

[0014] Figure 2 It is a functional block diagram of a control device of a machine tool according to a first embodiment of the present disclosure.

[0015] Figure 3 Shows an example of the relationship between the spindle phase and the position of the cutting tool.

[0016] Figure 4 Shows another example of the relationship between the spindle phase and the position of the cutting tool.

[0017] Figure 5 It is a functional block diagram of a control device of a machine tool according to a second embodiment of the present disclosure.

[0018] Figure 6 It is a functional block diagram of a control device of a machine tool according to a third embodiment of the present disclosure.

[0019] Figure 7 It is a flowchart showing the steps of the machining of the embodiment of the present disclosure. Detailed Description of the Invention

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0021] Figure 1 Indicates the machining of the embodiment of the present disclosure. As Figure 1 shown, the control device of the machine tool in the present embodiment operates at least one spindle S and at least one feed axis, and performs machining on the workpiece W with the cutting tool T. Among them, at least one spindle S rotates the cutting tool T relative to the workpiece W, and at least one feed axis moves the cutting tool T relative to the workpiece W. In Figure 1 , an example is shown in which the cutting tool T is moved in the feed direction Z by the feed axis to machine the outer peripheral surface of the cylindrical workpiece W rotated by the spindle S.

[0022] In addition, the machining of the present embodiment is performed while rotating the cutting tool T relative to the workpiece W and swinging the cutting tool T relative to the workpiece W in the feed direction Z, thereby being able to break up the chips continuously generated by the machining. The chips wind around the cutting tool T during machining, which becomes the main cause of machining defects, intermittent shutdowns, mechanical failures, etc. However, in the present embodiment, this cause can be avoided.

[0023] More specifically, as Figure 1 shown, the trajectory of the cutting tool T, that is, the tool path P, is set such that the current path overlaps the previous path. That is, it is set such that the portion machined in the previous path is included in the current path. In Figure 1In the example shown, the feed direction Z is set relative to the previous path, the phase of the mountain part is the same as the phase of the valley part of the current path, and the part machined in the previous path is included in the current path. Therefore, chatter C (air cutting) occurs where the tip of the cutting tool T separates from the surface of the workpiece W. As a result, the chips are reliably shredded.

[0024] Figure 2 is a functional block diagram of the control device 1 of the machine tool according to the first embodiment of the present disclosure. As Figure 2 shown, the control device 1 of the machine tool according to the present embodiment is configured to include a servo control device 10 that drives and controls a motor 30 for driving a feed axis.

[0025] As Figure 2 shown, the control device 1 of the machine tool according to the present embodiment includes a swing command generation unit 11, a motor control unit 12, an adder 13, an input unit 14, and a display unit 15.

[0026] The control device 1 of the machine tool according to the present embodiment generates a drive command for the motor 30 through a machining program. As Figure 2 shown, the generated drive command (position command, etc.) is input to the adder 13 of the servo control device 10 described later.

[0027] In addition, for example, a machining program for the control device 1 of the machine tool according to the present embodiment is generated by setting tool information, tool motion information, etc. for the machining shape generated by a CAD system (not shown) through a CAM system (not shown).

[0028] The swing command generation unit 11 generates a swing command for swinging the cutting tool T relative to the workpiece W in the feed direction Z. The generated swing command is input to the adder 13 described later. As Figure 2 shown, the swing command generation unit 11 includes a first swing condition determination unit 111, a second swing condition calculation unit 112, and a swing command calculation unit 113.

[0029] The first swing condition determination unit 111 determines one of a frequency parameter composed of a frequency or a frequency multiple that constitutes the swing command and an amplitude parameter composed of an amplitude or an amplitude multiple that also constitutes the swing command as the first swing condition. Then, as described later, through the second swing condition calculation unit 112, the other is calculated as the second swing condition using the correlation between the frequency parameter and the amplitude parameter. As a result, it is possible to shorten the time for setting conditions that were previously set one by one and confirmed.

[0030] More specifically, it is preferable that the first swing condition determination unit 111 determines the first swing condition based on at least one of the length of the chip, the surface roughness of the workpiece W, the amplitude of the swing, and the upper limit value of the first swing condition. Hereinafter, methods for determining the first swing condition based on the length of the chip, the surface roughness, the amplitude of the swing, and the upper limit value of the first swing condition will be described by way of example.

[0031] For example, when the first swing condition determination unit 111 determines the frequency multiplication factor as the first swing condition based on the length of the chip, the following mathematical formula (1-1) is used.

[0032] [Mathematical formula 1]

[0033]

[0034] In the above mathematical formula (1-1), I represents the frequency multiplication factor (times), D represents the diameter (mm) of the workpiece W, and L represents the length (mm) of the chip. The diameter D of the workpiece W can be obtained from the coordinate values of the tool positioned in the radial direction of the workpiece during machining. By substituting the desired chip length L into the above mathematical formula (1-1), the frequency multiplication factor I is obtained. By using the following mathematical formula (2-2) that defines the relationship between the frequency odds and the frequency, the frequency as the first swing condition can also be obtained based on the desired chip length L.

[0035] In addition, for example, when the first swing condition determination unit 111 determines the frequency multiplication factor as the first swing condition based on the surface roughness, the maximum value of the surface roughness corresponding to the frequency multiplication factor can be held as a table, and the frequency multiplication factor can be determined based on the desired surface roughness.

[0036] Alternatively, instead of obtaining the surface roughness itself, the deviation of the surface roughness for each workpiece phase can be obtained as the standard deviation, and the relationship between the standard deviation and the frequency multiplication factor can be held as a table. Here, Figure 3 and Figure 4 are used to explain the deviation of the surface roughness during the cutting process accompanied by the swing. Figure 3 and Figure 4 show an example and another example of the relationship between the spindle phase and the position of the cutting tool T. Specifically, Figure 3 shows the relationship between the spindle phase and the position of the cutting tool T when the frequency multiplication factor I as the first swing condition is 1.5 times and the amplitude multiplication factor K as the second swing condition calculated according to the following formula (2-1) is 1.0 times. In addition, Figure 4 shows the relationship between the spindle phase and the position of the cutting tool T when the frequency multiplication factor I as the first swing condition is 1.2 times and the amplitude multiplication factor K as the second swing condition calculated according to the following formula (2-1) is 1.701 times.

[0037] As can be seen from Figure 3 , when the spindle rotates one full turn, the phase is staggered by half a cycle amount. Thus, at a specific spindle phase, the phase of the peak portion in the previous tool path is consistent with the phase of the valley portion in the current tool path. At this specific phase, for example, near the spindle phase of 120°, the change in the feed per spindle rotation becomes larger. As a result, due to the influence of the corner radius of the tool tip, etc., the unevenness of the workpiece surface becomes larger and the surface roughness becomes larger. On the contrary, near the spindle phase of 180°, the feed per spindle rotation is always constant and the surface roughness becomes smaller. In such a case, according to the spindle phase, the deviation of the surface roughness becomes larger.

[0038] In contrast, in the case of Figure 4 , the spindle phase at which the feed per spindle rotation becomes larger is not constant. In such a case, the deviation of the surface roughness corresponding to the spindle phase becomes smaller. Since the deviation of the surface roughness sometimes also affects the roundness of the machined workpiece, there is also a case where the first wobbling condition is determined based on the deviation of the surface roughness.

[0039] In addition, the amplitude of the wobbling can be obtained based on the amplitude of the wobbling. Specifically, when the amplitude of the wobbling is X (mm), using the following formula (2-3), set K’ = X and K = X / F.

[0040] In addition, the frequency and amplitude of the wobbling motion are determined within the operable range according to the machine tool. It is also possible to lock the upper limit for the desired frequency and amplitude to determine the first wobbling condition.

[0041] The second wobbling condition calculation unit 112 calculates the other of the frequency parameter and the amplitude parameter as the second wobbling condition according to the first wobbling condition determined by the above first wobbling condition determination unit 111. In addition, the second wobbling condition calculation unit 112 calculates the second wobbling condition based on any one of the number of tools and the number of cutting edges and the first wobbling condition.

[0042] More specifically, the second wobbling condition calculation unit 112 uses the following formulas (2-1), (2-2) and (2-3) to calculate the second wobbling condition.

[0043] [Formula 2]

[0044]

[0045]

[0046] FK = K′......Formula (2-3)

[0047] Here, in the above mathematical expressions (2-1), (2-2), and (2-3), I represents the frequency multiplication factor (times), K represents the amplitude multiplication factor (times), n represents the number of tools or the number of tool edges (pieces), I’ represents the vibration frequency (Hz), S represents the spindle speed (per minute -1 ), K’ represents the amplitude (mm), and F represents the feed rate (mm / revolution). For example, when the frequency multiplication factor I is 1, it means that the spindle rotates 1 circle and swings 1 time. Additionally, when the amplitude multiplication factor K is 1, it means that the amplitude becomes the same as the feed amount (the movement amount in the feed direction) per 1 revolution of the spindle.

[0048] Furthermore, through the above mathematical expression (2-2), it is possible to calculate the value of one of the frequency and the frequency multiplication factor based on the value of the other. Similarly, according to the above mathematical expression (2-3), it is possible to calculate the value of one of the amplitude and the amplitude multiplication factor based on the value of the other. Therefore, by utilizing the relationships of these mathematical expressions (2-2) and (2-3) and the mathematical expression (2-1), it is possible to calculate the second swing condition based on the first swing condition.

[0049] In addition, it is preferable that the second swing condition calculation unit 112 calculates an amplitude parameter including a margin based on the vibration of the tip of the cutting tool T and the workpiece W as the second swing condition. The tip (mechanical front end) of the cutting tool T and the workpiece W vibrate in a bending manner due to the swing. Therefore, by calculating an amplitude parameter including a margin based on this vibration, it is possible to reliably generate chatter C to break the chips.

[0050] Here, the frequency parameter and the amplitude parameter of the swing command need to be finally determined according to the cutting process, so the user of the machine tool needs to set them. However, regarding the above-mentioned mechanical upper limit values and the degree of margin that needs to be set, they vary depending on the machine tool, so it is difficult for the user to set them. Therefore, the machine tool designer sets the upper limit value of the machine tool and the margin of the machine tool. Then, the user automatically determines the first swing condition and the second swing condition by setting conditions such as the diameter of the workpiece W, the hole diameter in the hole cutting process, and the length of the chips, and can easily perform swing cutting.

[0051] Specifically, the machine designer sets an amplitude multiplication factor K1 equivalent to the margin based on the vibration of the tip and the workpiece W so that the chips can be broken under the swing condition near the mechanical upper limit value. In addition, the upper limit value of the machine tool is also set. Then, according to the input value of the user to the control device 1 of the machine tool and the above-mentioned mechanical upper limit value, etc., the frequency multiplication factor I as the first swing condition is determined. Then, according to the determined frequency multiplication factor I, the amplitude multiplication factor K2 required for chatter C is calculated using the above mathematical expression (2-1), and the final amplitude multiplication factor K = K1 × K2 can be calculated.

[0052] Return Figure 2, the swing command calculation unit 113 calculates a swing command based on the first swing condition determined by the first swing condition determination unit 111 and the second swing condition calculated by the second swing condition calculation unit 112.

[0053] In addition, the swing command calculation unit 113 synchronizes the phase of the swing command with the phase of the main shaft for relative rotation of the cutting tool T and the workpiece W, eliminating the situation where the phase of the chatter vibration is offset relative to the main shaft phase. Thus, even for the first swing condition and the second swing condition calculated using the correlation between the frequency parameter and the amplitude parameter, the chips can be reliably shredded.

[0054] The adder 13 generates an overlapping command. Specifically, the adder 13 generates an overlapping command by adding (overlapping) the swing command generated by the swing command generation unit 11 to the cumulative value of the position deviation, which is the difference between the position feedback and the position command described above. The position feedback is based on the position detection of an encoder provided in the motor 30 of the feed axis (not shown).

[0055] The motor control unit 12 generates a torque command for driving the motor 30 of the feed axis based on the overlapping command generated by the adder 13, and controls the motor 30 according to the generated torque command. Thus, the motor 30 driving the feed axis reaches the command position with the swing.

[0056] The input unit 14 can input at least one of various parameters required for the first swing condition determination unit 111 to determine the first swing condition, various parameters required for the second swing condition calculation unit 112 to calculate the second swing condition, the priority condition described later, and the margin. Specifically, the input unit 14 can input variables in the above formulas (2-1), (2-2), and (2-3), the length of the chips, the surface roughness, the amplitude of the swing, the upper limit value of the first swing condition, the priority condition described later, the margin, etc. Based on the input values input by the user via the input unit 14, the determination of the first swing condition and the calculation and determination of the second swing condition can be performed.

[0057] The display unit 15 can display at least one of the input values input via the input unit 14, the first swing condition determined by the first swing condition determination unit 111, the second swing condition calculated by the second swing condition calculation unit 112, and various specifications determined based on the first swing condition and the second swing condition. The various specifications refer to the length of the chips, the surface roughness, the deviation of the surface roughness, the amplitude of the swing, the operation parameters of the machine tool, etc. Through the display of the display unit 15, it is easy for the user to set and confirm the swing condition.

[0058] Next, refer to Figure 5 The second embodiment of the present disclosure will be described. Figure 5This is a functional block diagram of the control device 1A of the machine tool according to the second embodiment of the present disclosure. As Figure 5 shown, compared with the control device 1 of the machine tool in the above-mentioned first embodiment, the control device 1A of the machine tool in the second embodiment has the same structure except for the different structures of the swing command generation unit 11A and the servo control device 10A. Specifically, in the second embodiment, there is an upper limit determination unit 114 that changes the upper limit of the above-mentioned first swing condition based on at least one of the upper limit value of the second swing condition and the upper limit value of the motion parameters of the machine tool.

[0059] When the upper limit determination unit 114 determines the upper limit value based on the second swing condition, for the second swing condition calculated according to the first swing condition, the upper limit value determined according to the motion upper limit of the machine tool is used to lock the second swing condition. When the lock is applied, the first swing condition is inversely calculated from the second swing condition and the above-mentioned formula (2-1). The finally determined first swing condition and second swing condition are notified to the swing command calculation unit 113.

[0060] In addition, the upper limit determination unit 114 determines the upper limit value based on the motion parameters of the machine tool. For example, the motion parameters of the machine tool include the feed speed and the feed acceleration. When restrictions are imposed by the feed speed and acceleration, the following formulas (3-1) to (3-5) are used to calculate the maximum feed speed and the maximum acceleration.

[0061] [Formula 3]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] Here, in the above-mentioned formulas (3-1) to (3-5), Y represents the movement command (position command), F represents the feed speed (mm / rev), S represents the spindle speed (per minute -1 ), I represents the frequency multiplication factor (times), and K represents the amplitude multiplication factor (times). The amplitude multiplication factor K and the frequency multiplication factor I corresponding to the second swing condition are restricted so that the maximum feed speed and the maximum acceleration calculated using the above-mentioned formulas (3-1) to (3-5) do not exceed the upper limit value. In addition, the conversion to the swing amplitude and the swing frequency uses the above-mentioned formulas (2-2) and (2-3).

[0068] Next, the third embodiment of the present disclosure will be described with reference to Figure 6 this.Figure 6 is a functional block diagram of the control device 1B of the machine tool according to the third embodiment of the present disclosure. As Figure 6 shown, compared with the control device 1 of the machine tool according to the first embodiment and the control device 1A of the machine tool according to the second embodiment, the control device 1B of the machine tool according to the third embodiment has the same structure except for the different structures of the swing command generation unit 11B and the servo control device 1B. Specifically, in the third embodiment, there is provided an optimum condition determination unit 115 that sets at least one of the length of the chip, surface roughness, frequency parameter, amplitude parameter, operation parameter of the machine tool, and various specifications determined based on them as a priority condition.

[0069] The various specifications are, for example, the amplitude of the swing, the deviation of the surface roughness, etc. The optimum condition determination unit 115 notifies the first swing condition determination unit 111 of the first swing condition in order to calculate the corresponding second swing condition based on the first swing condition within a predetermined range. Based on this notification, the first swing condition determination unit 111 and the second swing condition calculation unit 112 determine the first swing condition and the second swing condition. The optimum condition determination unit 115 calculates the priority condition based on the first swing condition and the second swing condition. In addition, it is simultaneously confirmed whether all the upper limit values of the conditions other than the priority condition are satisfied. For the first swing condition within a predetermined range, the priority condition is confirmed, and the first swing condition and the second swing condition that satisfy all the upper limit values and have the smallest priority condition are notified to the swing command calculation unit 113.

[0070] Specifically, for example, when the priority condition is the feed acceleration, the swing command is calculated based on the first swing condition and the second swing condition, and the maximum feed acceleration in this command is calculated. At the same time, it is confirmed whether the upper limit values of all the conditions including the feed acceleration are not exceeded, and recording is performed only when all the upper limit values are satisfied. The first swing condition gradually decreases from the upper limit value, and the confirmation continues until all the upper limit values of the conditions are not satisfied. At the end of the confirmation, the first swing condition and the second swing condition with the smallest feed acceleration are notified to the swing command calculation unit 113.

[0071] Next, with reference to Figure 7 the cutting process sequence of the embodiment of the present disclosure will be described. Here, Figure 7 is a flowchart showing the steps of the cutting process of the embodiment of the present disclosure.

[0072] First, in step S1, the first swing condition is determined. As the first swing condition, one of the frequency parameter and the amplitude parameter is selected.

[0073] In step S2, based on the first swing condition determined in step S1, a second swing condition is calculated. As the second swing condition, the other of the frequency parameter and the amplitude parameter is selected. That is, the other of the frequency parameter and the amplitude parameter that was not selected as the first swing condition in step S2 is calculated.

[0074] In step S3, based on the first swing condition determined in step S1 and the second swing condition calculated in step S2, a swing command is calculated.

[0075] In step S4, an overlapping command is generated by overlapping the swing command calculated in step S3 on the position command. Then, based on the generated overlapping command, drive control is performed on the motor 30 for driving the feed shaft. This ends this process.

[0076] According to the embodiment of the present disclosure, the following effects are achieved.

[0077] (1) In the embodiment of the present disclosure, there is provided a first swing condition determination unit 111 that determines one of the frequency parameter composed of the frequency or frequency multiplier of the swing command and the amplitude parameter composed of the amplitude or amplitude multiplier of the swing command as the first swing condition. In addition, there is provided a second swing condition calculation unit 112 that calculates the other of the frequency parameter and the amplitude parameter as the second swing condition according to the first swing condition determined by the first swing condition determination unit 111.

[0078] The frequency parameter and the amplitude parameter are mutually related. In the embodiment of the present disclosure, after one party is determined under a certain condition, the other party is calculated and determined, thereby being able to shorten the time for condition setting performed in the past. Therefore, according to the embodiment of the present disclosure, the frequency parameter and the amplitude parameter of the desired swing command capable of chopping chips can be determined quickly.

[0079] (2) In the embodiment of the present disclosure, the second swing condition calculation unit 112 calculates the second swing condition based on any one of the number of tools and the number of cutting edges and the first swing condition.

[0080] Thereby, the frequency parameter and the amplitude parameter of the desired swing command capable of chopping chips can be determined more reliably and quickly.

[0081] (3) In the embodiment of the present disclosure, the first swing condition determination unit 111 determines the first swing condition based on at least one of the length of the chips, the surface roughness of the workpiece W, the amplitude of the swing, and the upper limit value of the first swing condition.

[0082] Accordingly, it is possible to determine the first swing condition and the second swing condition that constitute the swing command so as to achieve a desired chip length, surface roughness, swing amplitude, or not exceed the upper limit value of the frequency or amplitude determined according to the machine tool.

[0083] (4) In the embodiment of the present disclosure, an upper limit determination unit 114 is provided, which changes the first swing condition based on at least one of the upper limit value of the second swing condition and the upper limit value of the operation parameters of the machine tool.

[0084] Accordingly, it is possible to determine the first swing condition and the second swing condition that constitute the swing command so as not to exceed the upper limit value of the second swing condition and the upper limit value of the operation parameters of the machine tool.

[0085] (5) In the embodiment of the present disclosure, an optimum condition determination unit 115 is provided, which sets at least one of the length of the chip, the surface roughness of the workpiece, the frequency parameter, the amplitude parameter, the operation parameters of the machine tool, and various specifications determined based on them as a priority condition. Then, through the optimum condition determination unit 115, based on the second swing condition calculated according to the first swing condition within a predetermined range, it is determined the first swing condition and the second swing condition for which the priority condition becomes the minimum.

[0086] Accordingly, in the case where there are multiple first swing conditions that can satisfy each condition, the priority condition is confirmed for the first swing conditions within a predetermined range, and it is possible to determine the first swing condition and the second swing condition that satisfy all conditions and for which the priority condition is the minimum and the upper limit value.

[0087] (6) In the embodiment of the present disclosure, the second swing condition calculation unit 112 uses the above formulas (2-1), (2-2), and (2-3) to calculate the second swing condition.

[0088] Accordingly, it is possible to reliably calculate the other of the frequency parameter and the amplitude parameter based on one of the frequency parameter and the amplitude parameter determined by the first swing condition determination unit 111.

[0089] (7) In the embodiment of the present disclosure, the second swing condition calculation unit 112 calculates the amplitude parameter including the margin based on the vibration of the tip of the tool T and the workpiece W as the second swing condition.

[0090] The tip of the tool T (mechanical front end) and the workpiece W vibrate in a bending manner due to the swing, but according to this embodiment, by calculating the amplitude parameter including the margin based on this vibration, it is possible to more reliably generate the chatter vibration C.

[0091] (8) In an embodiment of the present disclosure, at least one of an input unit 14 and a display unit 15 is provided. Here, the input unit 14 can input at least one of various parameters required for determining the first swing condition by the first swing condition determination unit 111, various parameters required for calculating the second swing condition by the second swing condition calculation unit 112, the above-mentioned priority condition, and the above-mentioned margin. In addition, the display unit 15 can display at least one of the input content input through the input unit 14, the first swing condition determined by the first swing condition determination unit 111, the second swing condition calculated by the above-mentioned second swing condition calculation unit, and various specifications determined based on the first swing condition and the second swing condition.

[0092] Accordingly, based on the input value input by the user through the input unit 14, it is possible to determine the first swing condition and calculate and determine the second swing condition. In addition, through the display of the display unit 15, it is easy for the user to set and confirm the swing condition.

[0093] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope that can achieve the object of the present invention are also included in the present invention.

[0094] For example, in the control device 1 of the machine tool in the above-described embodiment, a learning control unit may also be provided. The learning control unit calculates a correction amount of the overlap command based on the cumulative value of the position deviation up to one learning cycle before, and corrects by overlapping the calculated correction amount with the overlap command. The overlap command in the above-described embodiment is likely to cause a position deviation due to including a swing command, but the followability for the periodic swing command can be improved by the correction performed by the learning control unit.

[0095] Description of Reference Numerals

[0096] 1, 1A, 1B Control device of machine tool

[0097] 10, 10A, 10B Servo control device

[0098] 11, 11A, 11B Swing command generation unit

[0099] 12 Motor control unit

[0100] 13 Adder

[0101] 14 Input unit

[0102] 15 Display unit

[0103] 30 Motor

[0104] 111 First swing condition determination unit

[0105] 112 Second swing condition calculation unit

[0106] 113 Swing command calculation unit

[0107] 114 Upper limit determination unit

[0108] 115 Optimal condition determination unit

[0109] C Dry run

[0110] P Tool path

[0111] S Spindle

[0112] T Cutting tool

[0113] W Workpiece

[0114] Z Feed direction.

Claims

1. A control device for a machine tool, the machine tool performing machining while relatively swinging a tool and a workpiece, characterized in that the control device includes: a swing command calculation unit that calculates a command for a swing operation; a first swing condition determination unit that determines one of a frequency parameter composed of the frequency or frequency multiple of the swing command and an amplitude parameter composed of the amplitude or amplitude multiple of the swing command as a first swing condition; a second swing condition calculation unit that calculates the other of the frequency parameter and the amplitude parameter based on the first swing condition determined by the first swing condition determination unit as a second swing condition; and an upper limit determination unit that changes the first swing condition based on an upper limit value of a feed speed or an upper limit value of a feed acceleration, which is an operation parameter of the machine tool.

2. The control device for a machine tool according to claim 1, characterized in that the second swing condition calculation unit calculates the second swing condition based on any one of the number of tools and the number of cutting edges and the first swing condition.

3. The control device for a machine tool according to claim 1, characterized in that the first swing condition determination unit determines the first swing condition based on at least one of the length of the chip, the surface roughness of the workpiece, the amplitude of the swing, and the upper limit value of the first swing condition.

4. The control device for a machine tool according to claim 2, characterized in that the first swing condition determination unit determines the first swing condition based on at least one of the length of the chip, the surface roughness of the workpiece, the amplitude of the swing, and the upper limit value of the first swing condition.

5. A control device for a machine tool, the machine tool performing machining while relatively swinging a tool and a workpiece, characterized in that the control device includes: a swing command calculation unit that calculates a command for a swing operation; a first swing condition determination unit that determines one of a frequency parameter composed of the frequency or frequency multiple of the swing command and an amplitude parameter composed of the amplitude or amplitude multiple of the swing command as a first swing condition; a second swing condition calculation unit that calculates the other of the frequency parameter and the amplitude parameter based on the first swing condition determined by the first swing condition determination unit as a second swing condition; and an upper limit determination unit that locks the second swing condition by an upper limit value determined according to the operation upper limit of the machine tool, and changes the first swing condition based on the locked second swing condition.

6. The control device for a machine tool according to claim 5, characterized in that the second swing condition calculation unit calculates the second swing condition based on any one of the number of tools and the number of cutting edges and the first swing condition.

7. The control device for a machine tool according to claim 5, characterized in that the first swing condition determination unit determines the first swing condition based on at least one of the length of the chip, the surface roughness of the workpiece, the amplitude of the swing, and the upper limit value of the first swing condition.

8. The control device for a machine tool according to claim 6, characterized in that The first swing condition determination unit determines the first swing condition based on at least one of the length of the chip, the surface roughness of the workpiece, the amplitude of the swing, and the upper limit value of the first swing condition.

9. A control device for a machine tool, wherein the machine tool performs machining while relatively swinging a tool and a workpiece, and is characterized in that the control device includes: a swing command calculation unit that calculates a command for a swing operation; a first swing condition determination unit that determines one of a frequency parameter composed of the frequency or frequency multiplication factor of the swing command and an amplitude parameter composed of the amplitude or amplitude multiplication factor of the swing command as the first swing condition; a second swing condition calculation unit that calculates the other of the frequency parameter and the amplitude parameter as the second swing condition based on the first swing condition determined by the first swing condition determination unit; and an optimum condition determination unit that sets one of the length of the chip, the surface roughness of the workpiece, the frequency parameter, the amplitude parameter, the operation parameter of the machine tool, and the deviation of the amplitude and surface roughness determined based on these as a priority condition, the optimum condition determination unit determines the upper limit values of all conditions other than the priority condition among the first swing condition, the second swing condition, the frequency parameter, the amplitude parameter, the feed speed, and the feed acceleration based on the second swing condition calculated according to the first swing condition within a predetermined range, and the priority condition becomes the smallest first swing condition and second swing condition.

10. The control device for a machine tool according to claim 9, wherein the second swing condition calculation unit calculates the second swing condition based on any one of the number of tools and the number of cutting edges and the first swing condition.

11. The control device for a machine tool according to claim 9, wherein the first swing condition determination unit determines the first swing condition based on at least one of the length of the chip, the surface roughness of the workpiece, the amplitude of the swing, and the upper limit value of the first swing condition.

12. The control device for a machine tool according to claim 10, wherein the first swing condition determination unit determines the first swing condition based on at least one of the length of the chip, the surface roughness of the workpiece, the amplitude of the swing, and the upper limit value of the first swing condition.

13. The control device for a machine tool according to claim 9, wherein the second swing condition calculation unit calculates the second swing condition by the following mathematical formulas (2-1), (2-2), and (2-3), Mathematical formula (2-1): Mathematical formula (2-2): Mathematical formula (2-3): FK = K′ In the mathematical expressions (2-1), (2-2), and (2-3), I represents the frequency multiplication factor (times), K represents the amplitude multiplication factor (times), n represents the number of tools or the number of tool cutting edges (pieces), I' represents the vibration frequency (Hz), S represents the spindle speed (revolutions per minute -1 ), K' represents the amplitude (mm), and F represents the feed rate (mm / revolution).

14. The control device for a machine tool according to claim 13, wherein the second swing condition calculation unit includes calculating the amplitude parameter based on the margin of vibration of the tool tip of the tool and the workpiece as the second swing condition.

15. The control device for a machine tool according to claim 14, wherein The control device includes at least one of an input unit and a display unit. The input unit can input at least one of various parameters required for the first swing condition determination unit to determine the first swing condition, various parameters required for the second swing condition calculation unit to calculate the second swing condition, the priority condition, and the margin. The display unit can display at least one of the input content input through the input unit, the first swing condition determined by the first swing condition determination unit, the second swing condition calculated by the second swing condition calculation unit, and various specifications determined based on the first swing condition and the second swing condition.

Images