Control system

Abstract

A numerical control device (1) controls a machine tool (2) that performs cutting while relatively moving a tool (25) with respect to a workpiece (24). The numerical control device (1) has a vibration condition input unit (10) that inputs a vibration condition for vibrating the tool (25) with respect to the workpiece (24) along a movement path of the tool (25) with respect to the workpiece (24), and a discontinuous cutting determination unit (12) that determines whether cutting with vibration in accordance with the vibration condition is discontinuous cutting that produces a subdivided chip from the workpiece (24) based on the vibration condition.

Description

Technical Field

[0001] This invention relates to a control system for controlling working machinery that performs cutting operations. Background Technology

[0002] A machining machine is known to perform cutting operations on a workpiece by moving a cutting tool relative to the workpiece. In this machine, to prevent chips generated during cutting from becoming entangled with the workpiece or cutting tool, a method is sometimes used whereby the cutting tool vibrates relative to the workpiece to generate finer chips. By suppressing chip entanglement with the workpiece or cutting tool, the work of removing chips from the workpiece or cutting tool can be reduced. Furthermore, since damage to the workpiece caused by entangled chips is suppressed, the machining quality is improved.

[0003] Patent Document 1 discloses a control device that rotates a workpiece while simultaneously moving a tool relative to the workpiece in at least two axial directions via spindle rotation, and vibrates the tool along its movement path relative to the workpiece. The control device in Patent Document 1 generates an oscillation command for vibrating the tool based on a position command for moving the tool relative to the workpiece and the spindle rotation angle. Furthermore, the control device in Patent Document 1 corrects the oscillation command based on a position deviation obtained from the position command and feedback values ​​indicating the position of the tool or workpiece.

[0004] In the control device described in Patent Document 1, it is unnecessary to maintain tables containing specific data for tool vibration, such as the tool's forward and backward travel, forward and backward speeds. The control device described in Patent Document 1 eliminates the workload of creating tables corresponding to the various machining conditions in cutting operations. Furthermore, in the event of changes in the machining conditions of the machine tool, the control device described in Patent Document 1 can easily modify the commands for tool vibration to correspond to the changed machining conditions.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-182336 Summary of the Invention

[0006] According to the prior art described in Patent Document 1, there is no way to determine whether subdivided chips are generated based on the generated oscillation command. In the case of the control device described in the prior art, feedback values ​​are required in the correction of the oscillation command. Therefore, without trial processing, it is impossible to determine whether the generated oscillation command can reliably generate subdivided chips. Therefore, according to the prior art, there is a problem that the control device needs to expend a lot of effort in order to control the generation of subdivided chips.

[0007] The present invention was made in view of the above circumstances, and its object is to provide a control system that can easily realize the control of the generation of finely divided chips in cutting processes.

[0008] To address the aforementioned issues and achieve the objectives, the CNC device of the present invention controls a machine tool that performs cutting operations while moving a cutting tool relative to a workpiece. The CNC device of the present invention includes: a vibration condition input unit, which receives vibration conditions along the tool's movement path relative to the workpiece for causing the tool to vibrate relative to the workpiece; and an intermittent cutting determination unit, which determines, based on the vibration conditions, whether the cutting accompanied by vibration according to the vibration conditions is intermittent cutting of the workpiece and causes finely segmented chips to be generated from the workpiece during intermittent cutting.

[0009] The effects of the invention

[0010] The control system involved in this invention has the following effect: it can easily control the generation of finely divided chips during cutting. Attached Figure Description

[0011] Figure 1 This is a diagram showing the control system that includes the numerical control device according to Embodiment 1.

[0012] Figure 2 It is used for passing through Figure 1 The diagram illustrates the cutting process performed by the working machine included in the control system.

[0013] Figure 3 It is used for Figure 1 The diagram illustrates the vibration of the cutting tool in the working machine included in the control system shown.

[0014] Figure 4 This is a flowchart illustrating the sequence of operations of the CNC device involved in Implementation Method 1.

[0015] Figure 5 This is a diagram used to explain the determination in the intermittent cutting determination unit of the CNC device according to Embodiment 1.

[0016] Figure 6 This is a flowchart showing the sequence of processes performed by the vibration condition correction unit of the CNC device according to Embodiment 1.

[0017] Figure 7 This is a diagram showing the control system that includes the numerical control device according to Embodiment 2.

[0018] Figure 8 This is a diagram illustrating an example of dynamic rigidity information stored in the numerical control device according to Embodiment 2.

[0019] Figure 9 This is a flowchart showing the sequence of processes performed by the vibration condition correction unit of the CNC device according to Embodiment 2.

[0020] Figure 10 This is a diagram showing the control system that includes the numerical control device according to Embodiment 3.

[0021] Figure 11 It means Figure 10 A diagram showing an example of a display in the display device of the control system shown.

[0022] Figure 12 This is a diagram showing the control system that includes the numerical control device according to Embodiment 4.

[0023] Figure 13 This is a diagram illustrating examples of the hardware structure of the numerical control device according to embodiments 1 to 4. Detailed Implementation

[0024] The control system involved in the embodiments will now be described in detail based on the accompanying drawings.

[0025] Implementation method 1.

[0026] Figure 1 This diagram illustrates a control system incorporating the CNC device according to Embodiment 1. The control system includes the CNC device 1 according to Embodiment 1, a machine tool 2 performing cutting operations, and a drive unit 3 that drives the machine tool 2. The CNC device 1 controls the machine tool 2 by executing a machining program 50. The machine tool 2 cuts the workpiece 24 while moving a cutting tool 25 relative to the workpiece 24.

[0027] The CNC device 1 includes: a vibration condition input unit 10, which receives vibration conditions; a machining program input unit 11, which receives machining program 50; an intermittent cutting determination unit 12, which determines whether to perform intermittent cutting; a vibration condition correction unit 13, which corrects the vibration conditions input to the vibration condition input unit 10; and a command value generation unit 14, which generates command values.

[0028] Intermittent cutting will be described later.

[0029] The vibration condition input unit 10 inputs vibration conditions for causing the tool 25 to vibrate relative to the workpiece 24 along the movement path of the tool 25 relative to the workpiece 24. The vibration condition input unit 10 outputs vibration condition information 51, representing the input vibration conditions, to the intermittent cutting determination unit 12 and the vibration condition correction unit 13. The machining program input unit 11 outputs the input machining program 50 to the intermittent cutting determination unit 12 and the instruction value generation unit 14.

[0030] The intermittent cutting determination unit 12 determines whether cutting accompanied by vibration according to the vibration conditions is intermittent cutting based on vibration conditions. Intermittent cutting is intermittent cutting of the workpiece 24, and is cutting that causes finely divided chips to be generated from the workpiece 24. The intermittent cutting determination unit 12 outputs determination information 52 indicating the determination result to the vibration condition correction unit 13.

[0031] When the determination information 52 indicating that the cutting accompanied by vibration is not intermittent cutting is input to the vibration condition correction unit 13, the vibration condition correction unit 13 determines the vibration conditions that make the cutting accompanied by vibration intermittent cutting. Based on the result obtained from determining the vibration conditions, the vibration condition correction unit 13 corrects the vibration condition information 51. After the vibration condition information 51 has been corrected by the vibration condition correction unit 13, the vibration condition correction unit 13 outputs the corrected vibration condition information 51, i.e., the vibration condition information 53, to the command value generation unit 14.

[0032] On the other hand, when the determination information 52 indicating that the cutting accompanied by vibration is intermittent cutting is input to the vibration condition correction unit 13, the vibration condition correction unit 13 skips the correction of the vibration condition information 51. In the case of skipping the correction of the vibration condition information 51, the vibration condition correction unit 13 outputs the uncorrected vibration condition information 51, i.e., the vibration condition information 53, to the command value generation unit 14.

[0033] The command value generation unit 14 generates axis command values ​​54 based on the machining program 50 and vibration condition information 53. Axis command values ​​54 are commands used to control the spindle motor 22 and the servo motor 23. The command value generation unit 14 outputs the generated axis command values ​​54 to the drive unit 3.

[0034] The machine tool 2 has a spindle 20, a drive shaft 21, a spindle motor 22, and a servo motor 23. The spindle 20 rotates under the driving force generated by the spindle motor 22. The workpiece 24 rotates together with the spindle 20. The drive shaft 21 drives the tool 25 in linear motion under the driving force generated by the servo motor 23.

[0035] The drive unit 3 includes: a spindle servo control unit 30, which is a servo amplifier that controls the spindle motor 22; and a drive axis servo control unit 31, which is a servo amplifier that controls the servo motor 23. The spindle servo control unit 30 outputs a spindle motor current 55 to the spindle motor 22 based on the axis command value 54. The spindle motor 22 drives the spindle 20 according to the spindle motor current 55. The drive axis servo control unit 31 outputs a servo motor current 56 to the servo motor 23 based on the axis command value 54. The servo motor 23 drives the drive axis 21 according to the servo motor current 56.

[0036] The machine tool 2 rotates the workpiece 24 by the driving force generated by the spindle motor 22, and moves the cutting tool 25 by the driving force generated by the servo motor 23. The machine tool 2 rotates the workpiece 24 and moves the cutting tool 25 according to the machining program 50, thereby cutting the workpiece 24.

[0037] In embodiment 1, the movement of the cutting tool 25 relative to the workpiece 24 refers to the relative movement of the cutting tool 25 with respect to the workpiece 24. The machine tool 2 moves at least one of the workpiece 24 and the cutting tool 25, thereby moving the cutting tool 25 relative to the workpiece 24. That is, the machine tool 2 may move the cutting tool 25 without moving the workpiece 24, or it may move the workpiece 24 without moving the cutting tool 25. The machine tool 2 may also move both the workpiece 24 and the cutting tool 25. The machine tool 2 may have a drive shaft 21 for linearly driving the workpiece 24. The machine tool 2 can cut the workpiece 24 by rotating the cutting tool 25. The machine tool 2 can perform cutting operations such as drilling or grinding using a rotating cutting tool.

[0038] Figure 2 It is used for passing through Figure 1 The diagram illustrates the cutting process performed by the machine tool included in the control system. The X-axis and Z-axis are perpendicular to each other. The centerline 26 of the workpiece 24 coincides with the rotation center of the spindle 20. The direction of the Z-axis is the same as the direction of the centerline 26. The tool 25 moves relative to the workpiece 24 in the ZX plane while cutting the surface of the rotating workpiece 24. Figure 2 The dashed arrows shown indicate the movement path of the tool 25 relative to the workpiece 24.

[0039] The machine tool 2 vibrates the tool 25 along its travel path. Vibration along the travel path refers to a reciprocating motion within a range of the travel path. In the straight sections of the travel path, the tool 25 reciprocates along the straight line. In the curved sections of the travel path, the tool 25 reciprocates along the curve. The machine tool 2 vibrates the tool 25 using a driving force generated by the servo motor 23. The machine tool 2 vibrates the tool 25 while simultaneously moving the tool 25 along the travel path. Figure 2 The double-headed arrows shown indicate the direction in which the tool 25 vibrates.

[0040] In Embodiment 1, the vibration of the cutting tool 25 relative to the workpiece 24 refers to the relative vibration of the cutting tool 25 with respect to the workpiece 24. The working machine 2 causes at least one of the workpiece 24 and the cutting tool 25 to vibrate, thereby causing the cutting tool 25 to vibrate relative to the workpiece 24. That is, the working machine 2 may vibrate the cutting tool 25 instead of the workpiece 24, or it may vibrate the workpiece 24 instead of the cutting tool 25. The working machine 2 may also vibrate both the workpiece 24 and the cutting tool 25.

[0041] Figure 3 It is used for Figure 1 The diagram illustrates the vibration of the cutting tool in the working machine included in the control system shown. Figure 3 In the graph shown, the horizontal axis represents the rotation angle of the spindle 20. The vertical axis represents the position of the tool 25 in the workpiece 24 along the Z-axis. Figure 3 The white arrows shown indicate the feed direction of tool 25. The feed direction is the direction in which tool 25 moves relative to workpiece 24 and is along the Z-axis.

[0042] The tool 25 moves in the feed direction while vibrating along its travel path. As the tool 25 vibrates along this path and the workpiece 24 rotates, the tool 25 moves along the surface of the workpiece 24, tracing a sinusoidal trajectory. In the following description, this trajectory will be referred to as the vibration trajectory. The vibration trajectory can be... Figure 3 The graph shown represents this. In Figure 3 The vibration trajectory of the tool 25 with a vibration frequency of 1.5 times is shown during one revolution of the spindle 20.

[0043] The vibration trajectory is determined by the rotational speed "S" of the spindle 20, the feed rate "F" of the tool 25, the amplitude "A" of the vibration, and the angular frequency "ω" of the vibration. The rotational speed "S" is the number of rotations of the spindle 20 per unit time. The unit of rotational speed "S" is, for example, "r / min". The feed rate "F" is the amount of feed of the tool 25 relative to the workpiece 24 during one revolution of the spindle 20. The unit of feed rate "F" is, for example, "mm / r". In the following description, feed rate "F" is sometimes referred to as feed amount "F". The amplitude "A" represents the amplitude of the vibration of the tool 25 relative to the workpiece 24. The unit of amplitude "A" is, for example, "mm". The angular frequency "ω" is the angular frequency of the vibration of the tool 25 relative to the workpiece 24. The unit of angular frequency "ω" is, for example, "rad / s".

[0044] like Figure 3As shown, the rotation angle of the spindle 20 at time "t(n)" is set to 0 degrees. Time "t(n)" is the moment when a certain length of time "n" has elapsed since the reference time. The reference time is arbitrary, such as the moment when the cutting of workpiece 24 begins. The spindle 20 rotates one revolution from time "t(n)" to time "t(n+1)". The vibration trajectory 60 is the vibration trajectory representing the movement of the tool 25 from time "t(n)" to time "t(n+1)".

[0045] The rotation angle of the spindle 20 returns to 0 degrees at time "t(n+1)". The spindle 20 rotates one revolution from time "t(n+1)" to time "t(n+2)". The vibration trajectory 61 is the vibration trajectory representing the movement of the tool 25 from time "t(n+1)" to time "t(n+2)".

[0046] During the movement of the tool 25 along the vibration trajectory 61, when its position on the vibration trajectory 61 is further forward in the feed direction than its position on the vibration trajectory 60, the tool 25 cuts the workpiece 24. Here, the position of the tool 25 at the reference moment is set as the reference position, the distance between the reference position and the position on the vibration trajectory 61 is set as distance "d(n+1)", and the distance between the reference position and the position on the vibration trajectory 60 is set as distance "d(n)". The position on the vibration trajectory 61 that is further forward in the feed direction than its position on the vibration trajectory 60 indicates that the difference between distance "d(n+1)" and distance "d(n)", i.e., "d(n+1) - d(n)", is a positive value. The machine tool 2 cuts the workpiece 24 when "d(n+1) - d(n)" is a positive value.

[0047] “d(n+1)-d(n)” is equivalent to the thickness of the chips produced by cutting. In the following description, the chip thickness “D” represents the thickness of the chips produced from workpiece 24 by cutting and the thickness in the feed direction.

[0048] When "d(n+1) - d(n)" is negative, the tool 25 passes through the area where cutting occurred when the tool 25 traversed the vibration trajectory 60. When "d(n+1) - d(n)" is negative, the cutting of the workpiece 24 is interrupted. Figure 3 The shaded area represents the region where "d(n+1) - d(n)" is negative. Machine tool 2 performs intermittent cutting by repeatedly cutting when "d(n+1) - d(n)" is positive and interrupting cutting when "d(n+1) - d(n)" is negative. Machine tool 2 breaks the chips when "d(n+1) - d(n)" becomes negative, thereby generating finer chips.

[0049] The CNC device 1 generates a phase difference between vibration trajectories 60 and 61, thereby achieving intermittent cutting. Furthermore, when the phases of vibration trajectories 60 and 61 are synchronized, "d(n+1)-d(n)" remains constant. In this case, the chips are not broken, and the workpiece 24 is continuously cut.

[0050] The machine tool 2 generates finely divided chips, thereby preventing chips from entangled with the workpiece 24 or the tool 25. By preventing chip entanglement, the machine tool 2 reduces the amount of work required to remove chips from the workpiece 24 or the tool 25. Furthermore, by suppressing damage to the workpiece 24 caused by entangled chips, the machining quality associated with the machine tool 2 is improved.

[0051] Next, the operation of the CNC device 1 will be explained. Figure 4 This is a flowchart illustrating the sequence of operations of the CNC device involved in Implementation Method 1.

[0052] The operator using the machine tool 2 inputs vibration conditions into the vibration condition input unit 10. The vibration conditions input to the vibration condition input unit 10 are the values ​​of amplitude "A", angular frequency "ω", rotational speed "S", and feed rate "F". Thus, in step S1, the CNC device 1 acquires the vibration condition data. The vibration condition data consists of the values ​​of amplitude "A", angular frequency "ω", rotational speed "S", and feed rate "F". The vibration condition input unit 10 outputs vibration condition information 51, including the input vibration condition data, to the intermittent cutting determination unit 12 and the vibration condition correction unit 13. Furthermore, in Embodiment 1, the vibration condition data acquired by the CNC device 1 only needs to include at least one of the values ​​of amplitude "A", angular frequency "ω", rotational speed "S", and feed rate "F". Other values ​​may also be included in the vibration condition data.

[0053] In step S2, the CNC device 1 determines whether the cutting accompanied by vibration according to the vibration conditions is intermittent cutting. The intermittent cutting determination unit 12 determines whether to perform intermittent cutting based on the vibration condition information 51.

[0054] Here, the details of the processing performed by the intermittent cutting determination unit 12 will be explained. The chip thickness “D” is represented by the following formula (1).

[0055] Formula 1

[0056] D=F+Asin(ωt)-Asin(ωt-ω1)…(1)

[0057] F+Asin(ωt) represents the aforementioned vibration trajectory 61. Asin(ωt-ω1) represents the aforementioned vibration trajectory 60. Asin(ωt) and Asin(ωt-ω1) are functions that repeatedly increase or decrease with a certain amplitude and a certain period. According to the above formula (1), the chip thickness “D” is calculated by subtracting the vibration trajectory 60 from the vibration trajectory 61. “t” represents any time. “ω1” represents the phase difference between the vibration trajectory 60 and the vibration trajectory 61. As described above, the intermittent cutting determination unit 12 uses the above formula (1), which includes functions representing the vibration trajectories 60 and 61 of the tool 25, to calculate the chip thickness “D”.

[0058] The phase difference “ω1” is represented by the following equation (2).

[0059] Formula 2

[0060]

[0061] The intermittent cutting determination unit 12 calculates the chip thickness "D" based on the vibration condition information 51. If the minimum value of the calculated chip thickness "D" is less than zero, the intermittent cutting determination unit 12 determines that chip breakage exists and performs intermittent cutting. If the minimum value of the calculated chip thickness "D" is greater than or equal to zero, the intermittent cutting determination unit 12 determines that there is no chip breakage and does not perform intermittent cutting. As described above, if the calculated thickness is less than zero, the intermittent cutting determination unit 12 determines that the cutting accompanied by vibration is intermittent cutting.

[0062] Here, the method for finding the minimum value of the chip thickness "D" is explained. Based on the above equation (1) and the formula for the sum of trigonometric functions, the following equation (3) is obtained.

[0063]

Formula 3

[0064]

[0065] In equation (3) above, when the chip thickness “D” is at its minimum, the value of cos{(2ωt-ω1) / 2} is “1” or “-1”. Therefore, the intermittent cutting determination unit 12 can determine whether to perform intermittent cutting by whether there is a phase difference “ω1” satisfying equation (4) or (5). Equation (4) represents the case where cos{(2ωt-ω1) / 2}=1 is true. Equation (5) represents the case where cos{(2ωt-ω1) / 2}=-1 is true.

[0066] Formula 4

[0067]

[0068]

Formula 5

[0069]

[0070] Substituting equation (4) into equation (2), we obtain equation (6). Substituting equation (5) into equation (2), we obtain equation (7).

[0071]

Formula 6

[0072]

[0073]

Formula 7

[0074]

[0075] For example, it is possible to determine whether the above equation (6) or equation (7) is satisfied by using the solution of the geometry described below. Figure 5 This is a diagram used to explain the determination in the intermittent cutting determination unit of the CNC device according to Embodiment 1.

[0076] Figure 5 The circle shown is the unit circle of the set of points (cos(30ω / S), sin(30ω / S)). If the angle "30ω / S" satisfying the above equation (7) is taken as the first solution, then the range "R1" is the range of angles in which the first solution exists. If the angle "30ω / S" satisfying the above equation (6) is taken as the second solution, then the range "R2" is the range of angles in which the second solution exists. In addition, the amplitude "A" and the feed rate "F" are generally greater than or equal to zero, so the case where the amplitude "A" or the feed rate "F" is negative can be ignored.

[0077] The intermittent cutting determination unit 12 determines whether cutting accompanied by vibration according to the vibration condition information 51 is intermittent cutting based on the above formulas (6) and (7). The intermittent cutting determination unit 12 outputs the determination information 52 indicating the determination result to the vibration condition correction unit 13.

[0078] According to equation (1) above, the intermittent cutting determination unit 12 calculates the chip thickness "D" through operations including the addition or subtraction of functions and constants. The function is a function that repeatedly increases or decreases with a certain amplitude and a certain period. The condition that determines the certain amplitude includes the vibration amplitude "A". The condition that determines the certain period includes the vibration angular frequency "ω". The condition that determines the constant includes the feed rate "F".

[0079] According to equation (1) above, the vibration is represented as a sine wave in the calculation of the chip thickness "D". The intermittent cutting determination unit 12 can represent the vibration as a cosine wave and calculate the chip thickness "D". The intermittent cutting determination unit 12 can use Euler's formula to transform trigonometric functions into complex numbers and calculate the chip thickness "D" by using complex number operations.

[0080] If the cutting accompanied by vibration is not intermittent cutting (step S2, No), the CNC device 1 proceeds sequentially to step S3. In step S3, the CNC device 1 corrects the vibration conditions. If the determination information 52 indicating that the cutting accompanied by vibration is not intermittent cutting is input to the vibration condition correction unit 13, the vibration condition correction unit 13 corrects the vibration condition information 51. In this case, the vibration condition correction unit 13 outputs the corrected vibration condition information 51, i.e., vibration condition information 53, to the command value generation unit 14. Then, the CNC device 1 proceeds sequentially to step S4, which will be described later.

[0081] On the other hand, if the cutting accompanied by vibration is intermittent cutting (step S2, Yes), the CNC device 1 proceeds sequentially to step S4. If the determination information 52 indicating that the cutting accompanied by vibration is intermittent cutting is input to the vibration condition correction unit 13, the vibration condition correction unit 13 skips the correction of the vibration condition information 51. In this case, the vibration condition correction unit 13 outputs the uncorrected vibration condition information 51, i.e., the vibration condition information 53, to the command value generation unit 14.

[0082] Here, the details of the processing performed by the vibration condition correction unit 13 will be explained. Figure 6 This is a flowchart showing the sequence of processes performed by the vibration condition correction unit of the CNC device according to Embodiment 1.

[0083] In step S11, the vibration condition correction unit 13 determines whether the values ​​contained in the vibration condition information 51, namely the amplitude "A" and the feed amount "F", satisfy F / 2A > 1. If F / 2A > 1, the above equations (6) and (7) do not have real solutions, so the determination involved in the vibration condition correction unit 13 when correcting the vibration conditions is not performed.

[0084] If F / 2A > 1 is satisfied (step S11, Yes), the vibration condition correction unit 13 proceeds sequentially to step S12. On the other hand, if F / 2A > 1 is not satisfied (step S11, No), the vibration condition correction unit 13 proceeds sequentially to step S13, which will be described later.

[0085] In step S12, the vibration condition correction unit 13 modifies the vibration condition to satisfy F / 2A < 1. The vibration condition correction unit 13 increases the value of amplitude "A" until F / 2A < 1 is achieved. Alternatively, the vibration condition correction unit 13 decreases the value of feed "F" until F / 2A < 1 is achieved. In step S12, the modification of the vibration condition is either increasing the value of amplitude "A" or decreasing the value of feed "F". The vibration condition correction unit 13 can modify both amplitude "A" and feed "F". After modifying at least one of amplitude "A" and feed "F", the vibration condition correction unit 13 proceeds sequentially to step S13.

[0086] In step S13, the vibration condition correction unit 13 determines whether the values ​​of amplitude "A", angular frequency "ω", rotational speed "S", and feed rate "F" satisfy either equation (6) or equation (7) above. If neither equation (6) nor equation (7) is satisfied (step S13, No), the vibration condition correction unit 13 proceeds sequentially to step S14. On the other hand, if at least one of equations (6) and (7) is satisfied (step S13, Yes), the vibration condition correction unit 13 proceeds sequentially to step S17, which will be described later.

[0087] In step S14, the vibration condition correction unit 13 determines whether the values ​​of the angular frequency "ω" and the rotational speed "S" satisfy 30ω / S≥0. If 30ω / S≥0 is satisfied (step S14, Yes), in step S15, the vibration condition correction unit 13 modifies the vibration condition to satisfy the following equation (8). The vibration condition correction unit 13 modifies at least one of the angular frequency "ω" and the rotational speed "S" to satisfy equation (8).

[0088]

Form 8

[0089]

[0090] On the other hand, if 30ω / S≥0 is not satisfied (step S14, No), the vibration condition correction unit 13 changes the vibration condition in step S16 to satisfy the following equation (9). The vibration condition correction unit 13 changes at least one of the angular frequency "ω" and the rotational speed "S" to satisfy equation (9).

[0091]

Form 9

[0092]

[0093] In steps S15 and S16, the change in vibration conditions is a change in at least one of the angular frequency "ω" and the rotational speed "S". In step S15 or S16, after changing at least one of the angular frequency "ω" and the rotational speed "S", the vibration condition correction unit 13 sequentially proceeds to step S17.

[0094] As described above, the vibration condition correction unit 13 modifies the vibration conditions up to steps S11 to S16, thereby correcting the vibration condition information 51 so that the calculated chip thickness "D" is less than zero. In step S17, the vibration condition correction unit 13 outputs the corrected vibration condition information 51, i.e., vibration condition information 53, to the command value generation unit 14. Thus, the vibration condition correction unit 13 concludes its operation. Figure 6 The sequence of processes shown.

[0095] exist Figure 4 In step S4, the CNC device 1 generates axis command value 54. Machining program 50 and vibration condition information 53 are input to the command value generation unit 14. The command value generation unit 14 generates axis command value 54 based on machining program 50 and vibration condition information 53.

[0096] The axis command value 54 includes commands for controlling the spindle motor 22 and commands for controlling the servo motor 23. The commands for controlling the spindle motor 22 are angle commands or speed commands. The commands for controlling the servo motor 23 are position commands or speed commands. The command value generation unit 14 outputs the generated axis command value 54 to the drive unit 3. The axis command value 54 output based on the vibration condition information 53 only needs to include at least one of the commands for controlling the spindle motor 22 and the commands for controlling the servo motor 23. The CNC device 1 outputs the axis command value 54, thus concluding the process. Figure 4 The sequence of actions shown.

[0097] Furthermore, in the CNC device 1, the rotational speed "S" and feed rate "F" are not limited to being obtained by inputting them to the vibration condition input unit 10. The rotational speed "S" and feed rate "F" are sometimes included in the machining conditions described in the machining program 50. In this case, the intermittent cutting determination unit 12 can read at least one of the rotational speed "S" and feed rate "F" from the machining program 50. That is, the intermittent cutting determination unit 12 determines whether to perform intermittent cutting based on at least one of the machining conditions, the rotational speed "S" and the feed rate "F," and the input vibration condition.

[0098] According to Embodiment 1, the CNC device 1 is input with vibration conditions and determines whether cutting accompanied by vibration according to the vibration conditions is intermittent cutting based on the vibration conditions. The CNC device 1 does not need to pre-store a table containing specific data for vibrating the tool 25. The CNC device 1 eliminates the workload of creating tables corresponding to various machining conditions. When machining conditions change, the CNC device 1 can easily change the axis command value 54 in a manner corresponding to the changed machining conditions. Furthermore, the CNC device 1 can determine whether intermittent cutting is possible without using feedback values ​​obtained during machining. Trial machining is not required to determine whether intermittent cutting is possible. Therefore, the CNC device 1 has the effect that it can easily achieve control over the generation of finely divided chips during cutting.

[0099] In Embodiment 1, the mechanism that transmits the driving force generated by the servo motor 23 to the tool 25 is designed so that there is no reduction in gain when the tool 25 vibrates. That is, in Embodiment 1, the CNC device 1 treats the mechanism from the servo motor 23 to the tool 25 as a rigid body and determines whether to perform intermittent cutting. In Embodiment 2, which will be described next, the case where the determination of whether to perform intermittent cutting is made taking into account the reduction in gain in the mechanism from the servo motor 23 to the tool 25 will be explained.

[0100] Implementation method 2.

[0101] Figure 7 This diagram illustrates a control system incorporating the CNC device according to Embodiment 2. In Embodiment 2, structural elements identical to those in Embodiment 1 are labeled with the same reference numerals, and the differences from Embodiment 1 are primarily described. The control system includes the CNC device 1A according to Embodiment 2, a machine tool 2 for performing cutting operations, and a drive unit 3 for driving the machine tool 2.

[0102] The CNC device 1A includes a dynamic rigidity storage unit 15 for storing dynamic rigidity information 57. Additionally, the CNC device 1A includes a vibration condition input unit 10, a machining program input unit 11, a command value generation unit 14, an intermittent cutting determination unit 16, and a vibration condition correction unit 17. The processing performed by the intermittent cutting determination unit 16 differs from the processing performed by the intermittent cutting determination unit 12 in Embodiment 1. The processing performed by the vibration condition correction unit 17 differs from the processing performed by the vibration condition correction unit 13 in Embodiment 1.

[0103] Dynamic stiffness information 57 represents the dynamic stiffness of the mechanism including the servo motor 23 that drives the tool 25 and the tool 25. The dynamic stiffness of the mechanism including the servo motor 23 and the tool 25 is measured in advance, and the dynamic stiffness information 57 is stored in the dynamic stiffness storage unit 15.

[0104] The dynamic stiffness storage unit 15 stores the transfer function representing the dynamic stiffness of the drive shaft. The transfer function "FRF1(s)" is obtained through the relationship FRF1(s) = Xt(s) / Xs(s). "Xs(s)" represents the position of the servo motor 23. "Xt(s)" represents the position of the tool 25. "s" is the Laplace operator. The dynamic stiffness of the drive shaft can be represented by a discrete frequency transfer function. For example, a servo motor current 56 that causes the servo motor 23 to scan and vibrate flows in the servo motor 23, and the positions "Xs(s)" and "Xt(s)" at this time are sampled. The positions "Xs(s)" and "Xt(s)" are compared in the frequency region, thereby obtaining a discrete frequency transfer function.

[0105] The dynamic stiffness information 57 includes at least the gain "G(f)" in the transfer function "FRF1(s)" for each frequency. "f" represents the frequency of vibration represented by the axis command value 54. The dynamic stiffness information 57 is read from the intermittent cutting determination unit 16 and the vibration condition correction unit 17. The gain "G(f)" is the ratio of the amplitude of the actual vibration of the tool 25 to the amplitude of the vibration represented by the axis command value 54. The value of the gain "G(f)" varies depending on the frequency "f".

[0106] Figure 8 This diagram illustrates an example of dynamic stiffness information stored in the CNC device according to Embodiment 2. The dynamic stiffness information 57 is a table storing data on frequency "f" and gain "G(f)". The first column of the table stores the value of frequency "f" for each 1 Hz frequency, up to 100 Hz. The second column of the table stores the value of gain "G(f)" corresponding to each frequency "f". The gain "G(f)" is read from the dynamic stiffness storage unit 15 in the form of the table described above.

[0107] Next, the details of the processing performed by the intermittent cutting determination unit 16 will be explained. The intermittent cutting determination unit 16 determines whether to perform intermittent cutting based on the vibration condition information 51 and the dynamic stiffness information 57.

[0108] The chip thickness “D” is represented by the following formula (10).

[0109]

Formula 10

[0110] D=F+G(f)Asin(ωt)-G(f)Asin(ωt-ω1)…(10)

[0111] F+G(f)Asin(ωt) represents the vibration trajectory 61. G(f)Asin(ωt-ω1) represents the vibration trajectory 60. According to the above formula (10), the chip thickness “D” is calculated by subtracting the vibration trajectory 60 from the vibration trajectory 61. In the above formula (10), the vibration trajectory 61 and the vibration trajectory 60 are each multiplied by the gain “G(f)”. As a result, the intermittent cutting determination unit 16 can accurately calculate the vibration of the tool 25 caused by the servo motor 23 driven by the axis command value 54.

[0112] The phase difference between vibration trajectory 60 and vibration trajectory 61, i.e., the phase difference "ω1", is expressed by the following formula (11).

[0113]

Formula 11

[0114]

[0115] The intermittent cutting determination unit 16 calculates the chip thickness "D" based on vibration condition information 51 and dynamic rigidity information 57. If the minimum value of the chip thickness "D" is less than zero, the intermittent cutting determination unit 16 determines that chip breakage exists and performs intermittent cutting. If the minimum value of the chip thickness "D" is greater than or equal to zero, the intermittent cutting determination unit 16 determines that there is no chip breakage and does not perform intermittent cutting.

[0116] Here, the method for finding the minimum value of the chip thickness "D" is explained. Based on the above equation (10) and the formula for the sum of trigonometric functions, the following equation (12) is obtained.

[0117]

Formula 12

[0118]

[0119] In equation (12) above, when the chip thickness “D” is at its minimum, the value of cos{(2ωt-ω1) / 2} is “1” or “-1”. Therefore, the intermittent cutting determination unit 16 can determine whether to perform intermittent cutting by whether there is a phase difference “ω1” satisfying equation (13) or (14). Equation (13) represents the case where cos{(2ωt-ω1) / 2}=1 is true. Equation (14) represents the case where cos{(2ωt-ω1) / 2}=-1 is true.

[0120]

Formula 13

[0121]

[0122]

Formula 14

[0123]

[0124] In embodiment 2, the intermittent cutting determination unit 16 obtains the value of the gain "G(f)" corresponding to the angular frequency "ω" from the dynamic rigidity information 57 regarding the tool 25 vibrating at the angular frequency "ω". For the frequency "f" and the angular frequency "ω", the following equation (15) holds true.

[0125]

Formula 15

[0126]

[0127] Substituting equations (11) and (15) into equation (13), we obtain equation (16). Substituting equations (11) and (15) into equation (14), we obtain equation (17). Furthermore, the intermittent cutting determination unit 16 refers to... Figure 8 The table shown allows for the calculation of the gain "G(f)" corresponding to the frequency "f".

[0128]

Formula 16

[0129]

[0130]

Formula 17

[0131]

[0132] Intermittent cutting determination unit 16 determines whether cutting accompanied by vibration according to vibration condition information 51 is intermittent cutting. Intermittent cutting determination unit 16 outputs determination information 52 indicating the determination result to vibration condition correction unit 17.

[0133] According to equation (10) above, the intermittent cutting determination unit 16 calculates the chip thickness "D" through operations including the addition or subtraction of functions and constants. The function is a function that repeatedly increases or decreases with a certain amplitude and a certain period. The condition for determining the certain amplitude includes the vibration amplitude "A" and the gain "G(f)". The condition for determining the certain period includes the vibration angular frequency "ω". The condition for determining the constant includes the feed rate "F".

[0134] Next, the details of the processing performed by the vibration condition correction unit 17 will be explained. If the determination information 52 indicating that the cutting accompanied by vibration is not intermittent cutting is input to the vibration condition correction unit 17, the vibration condition correction unit 17 corrects the vibration condition information 51. In this case, the vibration condition correction unit 17 outputs the corrected vibration condition information 51, i.e., vibration condition information 53, to the command value generation unit 14.

[0135] On the other hand, if the determination information 52 indicating that the cutting accompanied by vibration is intermittent cutting is input to the vibration condition correction unit 17, the vibration condition correction unit 17 skips the correction of the vibration condition information 51. In this case, the vibration condition correction unit 17 outputs the uncorrected vibration condition information 51, i.e., the vibration condition information 53, to the command value generation unit 14.

[0136] Figure 9 This is a flowchart illustrating the sequence of processing performed by the vibration condition correction unit of the CNC device according to Embodiment 2. In step S21, the vibration condition correction unit 17 determines whether the values ​​contained in the vibration condition information 51, namely the amplitude "A" and the feed amount "F", satisfy F / 2A > 1. If F / 2A > 1, the above equations (16) and (17) do not have real solutions, therefore the determination involved in the vibration condition correction unit 17 when correcting the vibration conditions is not performed.

[0137] If F / 2A > 1 is satisfied (step S21, Yes), the vibration condition correction unit 17 proceeds sequentially to step S22. On the other hand, if F / 2A > 1 is not satisfied (step S21, No), the vibration condition correction unit 17 proceeds sequentially to step S23, which will be described later.

[0138] In step S22, the vibration condition correction unit 17 modifies the vibration condition to satisfy F / 2A < 1. The vibration condition correction unit 17 increases the value of amplitude "A" until F / 2A < 1 is achieved. Alternatively, the vibration condition correction unit 17 decreases the value of feed "F" until F / 2A < 1 is achieved. In step S22, the vibration condition is modified by either increasing the value of amplitude "A" or decreasing the value of feed "F". The vibration condition correction unit 17 can modify both amplitude "A" and feed "F". After modifying at least one of amplitude "A" and feed "F", the vibration condition correction unit 17 proceeds sequentially to step S23.

[0139] In step S23, the vibration condition correction unit 17 determines whether the values ​​of amplitude "A", angular frequency "ω", rotational speed "S", and feed rate "F" satisfy either equation (16) or equation (17) above. If neither equation (16) nor equation (17) is satisfied (step S23, No), the vibration condition correction unit 17 proceeds sequentially to step S24. On the other hand, if at least one of equations (16) and (17) is satisfied (step S23, Yes), the vibration condition correction unit 17 proceeds sequentially to step S25, which will be described later.

[0140] In step S24, the vibration condition correction unit 17 modifies the vibration conditions to satisfy the following equation (18). The vibration condition correction unit 17 searches for the values ​​of the angular frequency "ω" and the rotational speed "S" that satisfy equation (18). Thus, the vibration condition correction unit 17 modifies at least one of the angular frequency "ω" and the rotational speed "S" to satisfy equation (18). In step S24, the modification of the vibration conditions is a modification of at least one of the angular frequency "ω" and the rotational speed "S".

[0141]

Formula 18

[0142]

[0143] In implementation 2, the value of the gain "G(ω / 2π)" is determined by referring to... Figure 8 The values ​​obtained from the table shown indicate that the gain "G(ω / 2π)" is a nonlinear and discontinuous element. Therefore, it is impossible to solve for the angular frequency "ω" and rotational speed "S" using differentials. Therefore, the vibration condition correction unit 17 uses an exploratory method, such as the simplex method, to change at least one of the angular frequency "ω" and rotational speed "S". After changing at least one of the angular frequency "ω" and rotational speed "S", the vibration condition correction unit 17 proceeds to step S25.

[0144] As described above, the vibration condition correction unit 17 modifies the vibration conditions up to steps S21 to S24, thereby correcting the vibration condition information 51 so that the calculated chip thickness "D" is less than zero. In step S25, the vibration condition correction unit 17 outputs the corrected vibration condition information 51, i.e., vibration condition information 53, to the command value generation unit 14. Thus, the vibration condition correction unit 17 concludes its operation. Figure 9 The sequence of processes shown.

[0145] The vibration condition correction unit 17 takes into account the decrease in gain "G(f)" caused by the dynamic stiffness in the mechanism from servo motor 23 to tool 25, and corrects the vibration condition information 51 so that the calculated chip thickness "D" is less than zero. The vibration condition correction unit 17, taking into account the decrease in gain "G(f)", can correct the vibration conditions to enable intermittent cutting.

[0146] According to Embodiment 2, the CNC device 1A includes a dynamic rigidity storage unit 15 that stores dynamic rigidity information 57. The intermittent cutting determination unit 16 considers the decrease in gain "G(f)" caused by the dynamic rigidity in the mechanism from the servo motor 23 to the tool 25, and can determine whether to perform intermittent cutting. Even when the mechanism from the servo motor 23 to the tool 25 is not a rigid body and the gain "G(f)" decreases, the CNC device 1A can accurately determine whether to perform intermittent cutting.

[0147] Implementation method 3.

[0148] In Embodiment 1 described above, the CNC device 1 corrects the vibration conditions based on the determination information 52 in the vibration condition correction unit 13. In Embodiment 3, the range of vibration conditions that allow for intermittent cutting is displayed on the display device, and the operator selects the vibration conditions, thereby correcting the vibration conditions.

[0149] Figure 10 This diagram illustrates a control system incorporating the CNC device according to Embodiment 3. In Embodiment 3, structural elements identical to those in Embodiment 1 or 2 are labeled with the same reference numerals, and the structures different from those in Embodiment 1 or 2 are mainly described. The control system includes the CNC device 1B according to Embodiment 3, a cutting machine 2, a drive unit 3 for driving the cutting machine 2, and a display device 4.

[0150] The CNC device 1B includes a vibration condition input unit 10, a machining program input unit 11, an intermittent cutting determination unit 18, and a command value generation unit 19. The processing implemented by the intermittent cutting determination unit 18 differs from the processing implemented by the intermittent cutting determination unit 12 in Embodiment 1 and the processing implemented by the intermittent cutting determination unit 16 in Embodiment 2. The processing implemented by the command value generation unit 19 differs from the processing implemented by the command value generation unit 14 in Embodiment 1 or 2.

[0151] The display device 4 includes: an intermittent cutting condition calculation unit 40, which calculates the range of intermittent cutting conditions that can be changed; a judgment information display unit 41, which displays the judgment result obtained by the intermittent cutting judgment unit 18; an intermittent cutting condition display unit 42, which displays information indicating the range calculated by the intermittent cutting condition calculation unit 40; a change input unit 43, into which changeable conditions are input; and a correction condition input unit 44, into which correction conditions are input. The changeable conditions will be described later.

[0152] If the intermittent cutting determination unit 18 determines that the cutting accompanied by vibration is not intermittent cutting, it outputs determination information 52 indicating that it is not intermittent cutting to the determination information display unit 41. The intermittent cutting determination unit 18 outputs vibration condition information 51 to the command value generation unit 19. The determination information display unit 41 displays the case where intermittent cutting cannot be performed according to the vibration conditions input to the vibration condition input unit 10.

[0153] If the operator confirms the display on the determination information display unit 41, they input the changeable condition from the input vibration conditions to the change input unit 43. The operator specifies the changeable condition from the conditions of amplitude "A", angular frequency "ω", rotational speed "S", and feed rate "F" by inputting them to the change input unit 43. In Embodiment 3, the changeable condition is the vibration condition specified by the operator as a changeable condition.

[0154] Here, we will explain the processing performed by the display device 4, assuming that the changeable condition input to the change input unit 43 is amplitude "A". The change input unit 43 outputs change condition information 70, representing the changeable condition input by the operator, to the intermittent cutting condition calculation unit 40. The intermittent cutting condition calculation unit 40 calculates the range of solutions for amplitude "A" that satisfy the above equations (6) and (7). In this example, the changeable condition is amplitude "A", so based on the above equation (6), we obtain the following equation (19) representing the range of solutions for amplitude "A". In addition, based on the above equation (7), we obtain the following equation (20) representing the range of solutions for amplitude "A". Furthermore, since amplitude "A" is not negative, the range of solutions is limited to A > 0.

[0155]

Formula 19

[0156]

[0157]

Formula 20

[0158]

[0159] The intermittent cutting condition calculation unit 40 outputs cutting condition information 71, representing the range of amplitude "A" satisfying the above formula (19) or (20), to the intermittent cutting condition display unit 42. Based on the cutting condition information 71, the intermittent cutting condition display unit 42 displays the range of solutions for amplitude "A" that allows for intermittent cutting. In this example, the displayed range of solutions is related to one variable; therefore, the intermittent cutting condition display unit 42 displays the range of solutions using specific numerical values.

[0160] If the operator confirms the display on the intermittent cutting condition display unit 42, they determine the value of amplitude "A" from the range of solutions displayed and input the determined value into the correction condition input unit 44. As described above, the corrected value of amplitude "A" is input into the correction condition input unit 44. The correction condition input unit 44 outputs vibration condition information 72, which includes the corrected value of amplitude "A," to the command value generation unit 19. Vibration condition information 72 represents the corrected vibration condition. The command value generation unit 19 generates axis command value 54 based on the machining program 50, vibration condition information 51, and vibration condition information 72.

[0161] The above explanation is an example of the case where only one changeable condition is input to the change input unit 43. Two changeable conditions can also be input to the change input unit 43. Here, we will explain the case where the changeable conditions input to the change input unit 43 are rotational speed "S" and amplitude "A".

[0162] The intermittent cutting condition calculation unit 40 calculates the range of rotational speed "S" and amplitude "A" that satisfy the above formula (19) or (20). The intermittent cutting condition calculation unit 40 outputs the cutting condition information 71, which represents the range of rotational speed "S" and amplitude "A", to the intermittent cutting condition display unit 42.

[0163] The intermittent cutting condition display unit 42 displays the range of solutions for the rotational speed "S" and the amplitude "A" that enable intermittent cutting based on the cutting condition information 71. In this example, the range of solutions displayed is related to two variables, so the intermittent cutting condition display unit 42 represents the range of solutions in a two-dimensional plane.

[0164] Figure 11 It means Figure 10 A diagram showing an example of a display in the display device of the control system shown. Figure 11 The image shows an example of a screen displayed on the intermittent cutting condition display unit 42, and an example of displaying the ranges related to two changeable conditions. A display area 80 is provided on the screen to display the ranges of solutions related to the two variables. The horizontal axis in display area 80 represents the first variable, namely the rotational speed "S". The vertical axis in display area 80 represents the second variable, namely the amplitude "A". The shaded area in display area 80 represents the range of rotational speed "S" and amplitude "A" for which intermittent cutting is possible. The white area in display area 80 represents the range of rotational speed "S" and amplitude "A" for which intermittent cutting is not possible.

[0165] Additionally, the screen includes a column 81 displaying the vibration conditions before correction and a column 82 displaying the vibration conditions after correction. Column 81 displays the vibration condition information 51 input to the vibration condition input unit 10. Regarding the corrected vibration conditions (amplitude "A" and rotational speed "S") in column 82, the vibration condition information 72 input to the correction condition input unit 44 is displayed. Regarding the uncorrected vibration conditions (angular frequency "ω" and feed rate "F") in column 82, the vibration condition information 51 is displayed.

[0166] First, the intermittent cutting condition display unit 42 displays the values ​​of rotational speed "S" and amplitude "A" included in the vibration condition information 51 in the display area 80 using markers 83. If the operator confirms the display area 80, they input any value of rotational speed "S" and amplitude "A" from the range of rotational speed "S" and amplitude "A" that are suitable for intermittent cutting into the correction condition input unit 44.

[0167] For example, by operating the pointing device, moving the pointer within the display area 80, and clicking the pointing device, the values ​​of rotational speed "S" and amplitude "A" are input to the calibration condition input unit 44. The intermittent cutting condition display unit 42 displays the values ​​of rotational speed "S" and amplitude "A" input to the calibration condition input unit 44 on the display area 80 using markers 84. Alternatively, the values ​​of rotational speed "S" and amplitude "A" can also be manually input to the calibration condition input unit 44. Figure 11 The vibration condition correction in the example shown is a correction that decreases the amplitude "A" from "0.15" to "0.1" and increases the rotational speed "S" from "650" to "900".

[0168] The correction condition input unit 44 outputs vibration condition information 72, including the corrected rotational speed "S" and the corrected amplitude "A", to the command value generation unit 19. As described above, when the changeable condition input to the change input unit 43 is 2, the display device 4 can easily display the range related to the two changeable conditions.

[0169] According to Embodiment 3, the control system displays the determination information 52 on the display device 4, thereby indicating to the operator whether intermittent cutting is possible. The display device 4 calculates the range of intermittent cutting among the changeable conditions and displays information indicating the calculated range. If intermittent cutting is not possible based on the vibration conditions input to the vibration condition input unit 10, the control system can indicate to the operator that intermittent cutting is possible. The operator can enable the machine tool 2 to perform intermittent cutting without exploring the vibration conditions through trial and error. The operator can efficiently prepare for machining.

[0170] Implementation method 4.

[0171] Figure 12 This diagram illustrates the control system of the numerical control device according to Embodiment 4. In Embodiment 4, the control system has the same structure as in Embodiment 3 and the dynamic rigidity storage unit 15 of Embodiment 2. In Embodiment 4, structural elements that are the same as in Embodiments 1 to 3 are labeled with the same reference numerals, and the structures that are different from those in Embodiments 1 to 3 will be mainly described.

[0172] The CNC device 1C according to Embodiment 4 includes a vibration condition input unit 10, a machining program input unit 11, a dynamic rigidity storage unit 15, an intermittent cutting determination unit 18, and a command value generation unit 19. The processing implemented by the intermittent cutting determination unit 18 is different from the processing implemented by the intermittent cutting determination unit 18 in Embodiment 3. The processing implemented by the intermittent cutting condition calculation unit 40 is also different from the processing implemented by the intermittent cutting condition calculation unit 40 in Embodiment 3.

[0173] The intermittent cutting determination unit 18 determines whether to perform intermittent cutting based on vibration condition information 51 and dynamic stiffness information 57. The processing performed by the intermittent cutting determination unit 18 is the same as the processing performed by the intermittent cutting determination unit 16 in Embodiment 2. If the above formula (16) or (17) is satisfied, the intermittent cutting determination unit 18 determines that the cutting accompanied by vibration is intermittent cutting.

[0174] If the intermittent cutting determination unit 18 determines that the cutting accompanied by vibration is not intermittent cutting, it outputs determination information 52 indicating that it is not intermittent cutting to the determination information display unit 41. The intermittent cutting determination unit 18 outputs vibration condition information 51 to the command value generation unit 19. The determination information display unit 41 displays the case where intermittent cutting cannot be performed based on the vibration conditions input to the vibration condition input unit 10.

[0175] Similar to Embodiment 3, if the operator confirms the display on the determination information display unit 41, they input the changeable condition from the input vibration conditions to the change input unit 43. The operator specifies the changeable condition from the conditions of amplitude "A", angular frequency "ω", rotational speed "S" and feed rate "F" by inputting them to the change input unit 43.

[0176] Here, we will describe the processing performed by the display device 4, assuming that the changeable condition input to the change input unit 43 is amplitude "A". The change input unit 43 outputs change condition information 70, representing the changeable condition input by the operator, to the intermittent cutting condition calculation unit 40.

[0177] The intermittent cutting condition calculation unit 40 calculates the range of solutions for amplitude "A" that satisfy the above equations (16) or (17) obtained based on vibration condition information 51 and dynamic stiffness information 57. In this example, the condition can be changed to amplitude "A", so based on the above equation (16), the following equation (21) representing the range of solutions for amplitude "A" is obtained. In addition, based on the above equation (17), the following equation (22) representing the range of solutions for amplitude "A" is obtained. Furthermore, since amplitude "A" cannot be negative, the range of solutions is restricted to A > 0.

[0178]

Formula 21

[0179]

[0180]

Formula 22

[0181]

[0182] The intermittent cutting condition calculation unit 40 outputs cutting condition information 71, representing the range of amplitude "A" satisfying the above formula (21) or (22), to the intermittent cutting condition display unit 42. Based on the cutting condition information 71, the intermittent cutting condition display unit 42 displays the range of solutions for amplitude "A" that can be intermittently cut. Similar to Embodiment 3, the intermittent cutting condition display unit 42 can display the range of solutions that can be intermittently cut for the two changeable conditions.

[0183] According to Embodiment 4, the CNC device 1C can achieve the same effect as in Embodiment 3. Furthermore, similar to Embodiment 2, the CNC device 1C can accurately determine whether to perform intermittent cutting even when the mechanism from the servo motor 23 to the tool 25 is not a rigid body and the gain is reduced. If the control system cannot perform intermittent cutting based on the vibration conditions input to the vibration condition input unit 10, it can alert the operator to the vibration conditions under which intermittent cutting is possible.

[0184] Next, the hardware structure of the numerical control devices 1, 1A, 1B, and 1C involved in embodiments 1 to 4 will be described. Figure 13 This is a diagram illustrating examples of the hardware structure of the CNC device according to embodiments 1 to 4. Figure 13 The diagram shows the hardware structure for implementing the functions of CNC devices 1, 1A, 1B, and 1C by using hardware that executes the program.

[0185] The CNC devices 1, 1A, 1B, and 1C are computer systems equipped with a control program, which is a program used to control the machine tool 2 according to the machining program 50. The CNC devices 1, 1A, 1B, and 1C have a processor 91 that performs various processes, a built-in memory 92, an interface circuit 93 for inputting information to and outputting information from the CNC devices 1, 1A, 1B, and 1C, a storage device 94 for storing information, and an input device 95 for receiving input information.

[0186] Processor 91 is a CPU (Central Processing Unit). Processor 91 can be a processing device, a computing device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor). Memory 92 is RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), or EEPROM (Electrically Erasable Programmable Read Only Memory).

[0187] Storage device 94 is either an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The control program that enables the computer to function as numerical control devices 1, 1A, 1B, and 1C is stored in storage device 94. Processor 91 reads the program stored in storage device 94 into memory 92 and executes it. Input device 95 is a device such as a keyboard or pointing device. Interface circuit 93 communicates with drive unit 3 and display device 4.

[0188] The control program can be stored on a storage medium that can be read by a computer system. The CNC devices 1, 1A, 1B, and 1C can store the control program recorded on the storage medium into memory 92. The storage medium can be a floppy disk (i.e., a portable storage medium) or semiconductor memory (i.e., flash memory). The control program can also be installed into the computer system from other computers or server devices via a communication network.

[0189] The functions of the intermittent cutting determination units 12, 16, 18, vibration condition correction units 13, 17, and command value generation units 14, 19 in CNC devices 1, 1A, 1B, and 1C are realized through a combination of processor 91 and software. These functions can be realized through a combination of processor 91 and firmware, or through a combination of processor 91, software, and firmware. The software or firmware is described as a program and stored in storage device 94.

[0190] The function of the dynamic rigidity storage unit 15 in CNC devices 1A and 1C is realized by using the storage device 94. The functions of the vibration condition input unit 10 and the machining program input unit 11 in CNC devices 1, 1A, 1B and 1C are realized by using the input device 95.

[0191] The function of display device 4 is to use with Figure 13 The hardware structure shown is the same as that implemented in the hardware structure. Display device 4 has... Figure 13 The structural elements shown are displayed on a monitor that displays information. The function of the intermittent cutting condition calculation unit 40 is achieved through a combination of processor 91 and software. The function of the intermittent cutting condition calculation unit 40 can be achieved through a combination of processor 91 and firmware, or through a combination of processor 91, software, and firmware. The functions of the change input unit 43 and the correction condition input unit 44 are achieved through the input device 95. The functions of the judgment information display unit 41 and the intermittent cutting condition display unit 42 are achieved through the monitor.

[0192] The structures shown in the above embodiments illustrate one example of the content of the present invention. The structures of each embodiment can be combined with other known technologies. The structures of each embodiment can also be appropriately combined with each other. A portion of the structure of each embodiment can be omitted or modified without departing from the spirit of the present invention.

[0193] Explanation of the label

[0194] 1. 1A, 1B, 1C CNC devices; 2. Working machine; 3. Drive unit; 4. Display device; 10. Vibration condition input unit; 11. Machining program input unit; 12, 16, 18. Intermittent cutting judgment unit; 13, 17. Vibration condition correction unit; 14, 19. Command value generation unit; 15. Dynamic rigidity storage unit; 20. Spindle; 21. Drive axis; 22. Spindle motor; 23. Servo motor; 24. Workpiece; 25. Tool; 26. Centerline; 30. Spindle servo control unit; 31. Drive axis servo control unit; 40. Intermittent cutting condition calculation unit; 41. Judgment unit. Information display unit, 42 Intermittent cutting condition display unit, 43 Change input unit, 44 Correction condition input unit, 50 Machining program, 51, 53, 72 Vibration condition information, 52 Judgment information, 54 Axis command value, 55 Spindle motor current, 56 Servo motor current, 57 Dynamic rigidity information, 60, 61 Vibration trajectory, 70 Change condition information, 71 Cutting condition information, 80 Display area, 81, 82 Columns, 83, 84 Markers, 91 Processor, 92 Memory, 93 Interface circuit, 94 Storage device, 95 Input device.

Claims

1. A control system having: A machine tool that performs cutting operations while moving the cutting tool relative to the workpiece. A numerical control device that controls the machine tool; and Display device, The control system is characterized by, The numerical control device has: A vibration condition input unit is provided, which receives vibration conditions along the movement path of the tool relative to the workpiece to cause the tool to vibrate relative to the workpiece. as well as The intermittent cutting determination unit determines, based on the vibration conditions, whether cutting accompanied by vibration according to the vibration conditions is intermittent cutting of the workpiece and causes subdivided chips to be generated from the workpiece during intermittent cutting. The display device has: The determination information display unit displays the determination result of the intermittent cutting determination unit; The input unit is modified by inputting the vibration conditions, which are specified as changeable conditions. as well as The intermittent cutting condition calculation unit calculates the range within which the intermittent cutting can be performed, among the conditions that can be changed.

2. The control system according to claim 1, characterized in that, The vibration conditions include at least one of the following: the amplitude of the vibration, the rotational speed of the spindle that rotates the workpiece, the feed rate of the tool, and the angular frequency of the vibration.

3. The control system according to claim 1, characterized in that, The intermittent cutting determination unit determines whether to perform the intermittent cutting based on the vibration conditions and the machining conditions recorded in the machining program used to control the machine tool.

4. The control system according to claim 3, characterized in that, The machining conditions include at least one of the rotational speed of the spindle that rotates the workpiece and the feed rate of the cutting tool.

5. The control system according to any one of claims 1 to 4, characterized in that, The intermittent cutting determination unit calculates the thickness of the chips generated from the workpiece by the cutting process and the thickness in the feed direction of the tool based on the vibration conditions. If the calculated thickness is less than zero, the cutting accompanied by the vibration is determined to be intermittent cutting.

6. The control system according to claim 5, characterized in that, The intermittent cutting determination unit calculates the thickness using a function that repeatedly increases and decreases with a certain amplitude and a certain period. The amplitude of the vibration is included in the conditions that determine the certain amplitude. The angular frequency of the vibration is included in the conditions that determine the certain period.

7. The control system according to claim 6, characterized in that, The intermittent cutting determination unit calculates the thickness by performing addition or subtraction operations involving the function and constants. The feed rate of the tool is included in the conditions that determine the constant.

8. The control system according to any one of claims 1 to 7, characterized in that, The CNC device has a dynamic rigidity storage unit that stores dynamic rigidity information representing the dynamic rigidity of the mechanism, including the motor that drives the tool and the tool itself. The intermittent cutting determination unit determines whether to perform the intermittent cutting based on the vibration conditions and the dynamic rigidity information.

9. The control system according to claim 8, characterized in that, The dynamic stiffness information includes the ratio of the amplitude of the actual vibration of the cutting tool to the amplitude of the vibration represented by the command used to control the motor, i.e., the gain. The gain value varies depending on the frequency of the vibration indicated by the instruction.

10. The control system according to claim 9, characterized in that, The intermittent cutting determination unit calculates the thickness of the chips generated from the workpiece by the cutting process and the thickness in the feed direction of the tool based on the vibration conditions and the gain. If the calculated thickness is less than zero, the cutting accompanied by the vibration is determined to be intermittent cutting.

11. The control system according to claim 10, characterized in that, The intermittent cutting determination unit calculates the thickness using a function that repeatedly increases and decreases with a certain amplitude and a certain period. The conditions for determining the certain amplitude include the amplitude of the vibration and the gain. The angular frequency of the vibration is included in the conditions that determine the certain period.

12. The control system according to any one of claims 1 to 11, characterized in that, The CNC device includes a vibration condition correction unit, which corrects the vibration conditions input to the vibration condition input unit. The vibration condition correction unit corrects at least one of the vibration amplitude, the rotational speed of the spindle that rotates the workpiece, the feed rate of the tool, and the angular frequency of the vibration based on a determination result indicating that the cutting accompanied by the vibration is not the intermittent cutting.

13. The control system according to claim 12, characterized in that, The vibration condition correction unit corrects the vibration conditions so that the calculation result related to the thickness of the chips generated from the workpiece by the cutting process and the thickness in the feed direction of the tool is less than zero.

14. The control system according to any one of claims 1 to 13, characterized in that, The display device has an intermittent cutting condition display section that displays information representing the range calculated by the intermittent cutting condition calculation section.

Images