Numerical control device

Abstract

This numerical control device controls a servomotor (71x) and a brake device (711x) for braking the servomotor, and causes a machine tool to perform vibration cutting, and is provided with an estimation unit (482) that estimates the deterioration of the brake device (711x) on the basis of the number of vibrations of micro-vibrations accompanying the vibration cutting.

Description

Technical Field

[0001] The present invention relates to a numerical control device for controlling vibration cutting. Background Art

[0002] A servo motor controlled by a numerical control device usually has a braking device, for example, to prevent a feed table that can move relative to the vertical direction from falling when the power is OFF. The components constituting the braking device are worn due to repeated braking operations, etc., and the life of the braking device expires due to the wear of these components. Therefore, it is important to grasp the deterioration and life of the braking device in advance to prevent problems and unexpected failures.

[0003] Various techniques have been proposed for grasping the deterioration of the braking device. For example, in Patent Document 1, the work amount of an electromagnetic brake is calculated, and the total work amount of the electromagnetic brake is calculated by accumulating and summing the work amounts of the electromagnetic brake during each emergency stop braking operation of the machine tool. The life of the electromagnetic brake is monitored based on the total work amount of the electromagnetic brake.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006 - 155199 Summary of the Invention

[0005] However, in the above Patent Document 1, it is limited to the monitoring of deterioration caused by braking operations. For example, in a machine tool performing vibration cutting, it is impossible to grasp the fastening hub worn due to the vibration of vibration cutting, or the deterioration of the braking device having a friction plate, etc. as components caused by vibration cutting.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a numerical control device capable of grasping the deterioration of a braking device that applies braking to a servo motor caused by vibration cutting.

[0007] To achieve the above object, the numerical control device according to the present invention controls a servo motor and a braking device that applies braking to the servo motor, and causes a machine tool to perform vibration cutting. The numerical control device has an estimation unit that estimates the deterioration of the braking device based on the number of vibrations of minute vibrations accompanying vibration cutting.

[0008] Effects of the Invention

[0009] According to the present invention, it is possible to provide a numerical control device capable of grasping the deterioration of a braking device that applies braking to a servo motor caused by vibration cutting. Brief Description of the Drawings

[0010] Figure 1 It is a diagram showing a structural example of the numerical control device according to the embodiment.

[0011] Figure 2 This is a diagram for explaining an installation example of the braking device related to the embodiment.

[0012] Figure 3 This is a diagram for explaining the operation of the braking device related to the embodiment.

[0013] Figure 4 This is a diagram for explaining an example of the structure of the fastening hub of the braking device related to the embodiment.

[0014] Figure 5 This is a diagram showing an example of the processing executed by the numerical control device related to the embodiment.

[0015] Figure 6 This is a diagram showing an example of information on the relationship between the execution time of vibration cutting related to the embodiment and the amount of wear in the fastening hub of the braking device.

[0016] Figure 7 This is a diagram showing an example of a display screen output by the numerical control device related to the embodiment.

[0017] Figure 8 This is a diagram showing the operating conditions of vibration cutting control related to the embodiment.

[0018] Figure 9 This is a schematic diagram showing an example of vibration waveforms before and after the change of the operating conditions of vibration cutting control related to the embodiment.

[0019] Figure 10 This is a diagram showing another example of the display screen output by the numerical control device related to the embodiment.

[0020] Figure 11 This is a diagram showing a structural example of the numerical control device related to the modification example.

[0021] Figure 12 This is a diagram showing an example of the processing executed by the numerical control device related to the modification example.

[0022] Figure 13 This is a diagram for explaining the operation of the braking device related to other embodiments.

[0023] Figure 14 This is a diagram showing a hardware structural example of the control arithmetic unit related to the embodiment and the modification example. Specific Embodiments

[0024] Next, with reference to the accompanying drawings, the numerical control device related to the embodiment will be described in detail based on the drawings. In addition, the present invention is not limited by these embodiments.

[0025] Embodiment

[0026] Figure 1 is a block diagram showing an example of the numerical control device 1 related to the embodiment. The Figure 1 numerical control (NC) device 1 shown, for example, for a machine tool performing cutting, is a computer that controls vibration cutting in which a tool vibrates while machining. The numerical control device 1 has an input operation unit 2, an output unit 3, and a control arithmetic unit 4. In addition, Figure 1 shows, for example, a drive unit 7 as a component of the machine tool. In addition, the drive unit 7 may also be an element independent of the machine tool.

[0027] The drive unit 7 is a mechanism connected to the control arithmetic unit 4 that drives at least one of a tool for machining a workpiece that is a machining object of the machine tool and the workpiece. In the present embodiment, the drive unit 7 is, for example, a mechanism that rotates the workpiece while driving the tool in two directions, a direction parallel to the X-axis direction and a direction parallel to the Z-axis direction, to machine the workpiece. The X-axis direction is, for example, the vertical direction, that is, the direction of gravity. The Z-axis direction is, for example, the horizontal direction. In addition, in the present embodiment, the central axis of the workpiece is defined as the Z-axis, and the direction orthogonal to the Z-axis is defined as the X-axis. In addition, since the axial direction is related to the mechanical structure, it is not limited to the above directions.

[0028] The drive unit 7 has an X-axis servo motor 71x, a detector 72x, and an X-axis servo control unit 73x. The X-axis servo motor 71x moves the tool on the X-axis defined on the numerical control device 1. The detector 72x detects the position and speed of the X-axis servo motor 71x. The X-axis servo control unit 73x performs feedback control of the X-axis servo motor 71x based on an instruction from the numerical control device 1 and the position information and speed information detected by the detector 72x. Regarding feedback control, hereinafter, feedback is also referred to as FB. The X-axis servo control unit 73x performs FB control of the X-axis servo motor 71x, thereby realizing the movement of the tool in the X-axis direction. In addition, the drive unit 7 outputs the position information detected by the detector 72x to the control arithmetic unit 4 as the FB vibration movement amount of the X-axis.

[0029] In addition, the drive unit 7 includes a Z-axis servo motor 71z, a detector 72z, and a Z-axis servo control unit 73z. The Z-axis servo motor 71z moves a tool along the Z-axis defined on the numerical control device 1. The detector 72z detects the position and speed of the Z-axis servo motor 71z. The Z-axis servo control unit 73z performs FB control of the Z-axis servo motor 71z based on an instruction from the numerical control device 1 and the position information and speed information detected by the detector 72z. By performing FB control of the Z-axis servo motor 71z, the Z-axis servo control unit 73z controls the movement of the tool in the Z-axis direction. In addition, the drive unit 7 outputs the position information detected by the detector 72z to the control arithmetic unit 4 as the FB vibration movement amount of the Z-axis.

[0030] Furthermore, the machine tool may have one or two or more tool carriers. When the machine tool has two or more tool carriers, the drive unit 7 includes, for each tool carrier, two or more sets of an X-axis servo motor 71x, a detector 72x, and an X-axis servo control unit 73x, a Z-axis servo motor 71z, a detector 72z, and a Z-axis servo control unit 73z.

[0031] In addition, the drive unit 7 includes a spindle motor 71s, a detector 72s, and a spindle control unit 73s. The spindle motor 71s rotates a spindle, which rotates a workpiece to be machined. The detector 72s detects the position and rotational speed of the spindle motor 71s. The spindle control unit 73s performs FB control of the spindle motor 71s based on an instruction from the numerical control device 1 and the position information and speed information detected by the detector 72s. By performing FB control of the spindle motor 71s, the spindle control unit 73s controls the rotational movement of the workpiece to be machined. In addition, the rotational speed detected by the detector 72s corresponds to the rotational speed of the spindle motor 101s.

[0032] Furthermore, the machine tool may machine two or more workpieces simultaneously. When the machine tool machines two or more workpieces simultaneously, the drive unit 7 includes two or more sets of a spindle motor 71s, a detector 72s, and a spindle control unit 73s. At this time, the machine tool has, for example, two or more tool carriers.

[0033] The input operation unit 2 is a unit for inputting information to the control arithmetic unit 4. The input operation unit 2 is constituted by an input unit such as a keyboard, buttons, or a mouse, for example. The input operation unit 2 inputs, for example, commands input by an operator to the numerical control device 1, input of a machining program number, input of parameters related to vibration cutting, etc. to the control arithmetic unit 4.

[0034] The output unit 3 is a unit that outputs information from the control arithmetic unit 4. The output unit 3 is constituted by a display unit such as a liquid crystal display device, for example. In the output unit 3, the information processed by the control arithmetic unit 4 is displayed on the display screen. In addition, in the embodiment, a display unit is provided as the output unit 3, but the structure is not limited thereto. For example, if the numerical control device 1 is connected to a network, the output unit 3 may be a display device connected to the network or a display device of a computer. Additionally, the output unit 3 may also be a sound device such as a speaker.

[0035] The control arithmetic unit 4 includes an input control unit 41, a data setting unit 42, a storage unit 43, an output control unit 44, an analysis processing unit 45, a control signal processing unit 46, a PLC (Programmable Logic Controller) circuit unit 47, an interpolation processing unit 48, a acceleration / deceleration processing unit 49, and an axis data input / output unit 50. In addition, in the present embodiment, the PLC circuit unit 47 is arranged inside the control arithmetic unit 4, but the PLC circuit unit 47 may also be arranged outside the control arithmetic unit 4.

[0036] The input control unit 41 receives the information input from the input operation unit 2. The data setting unit 42 stores the information received through the input control unit 41 in the storage unit 43. That is, the input information received by the input operation unit 2 is written into the storage unit 43 via the input control unit 41 and the data setting unit 42.

[0037] The storage unit 43 has a parameter storage area 431, a machining program storage area 432, a display data storage area 433, and a shared area 434.

[0038] In the parameter storage area 431, parameters used for the processing of the control arithmetic unit 4 are stored, specifically, control parameters, servo parameters, tool data, and parameters related to vibration cutting for operating the numerical control device 1.

[0039] In the machining program storage area 432, a machining program including one or more program blocks used for machining a workpiece is stored. In addition, in the present embodiment, the machining program includes a movement instruction for moving a tool, a rotation instruction for rotating a spindle, and the like.

[0040] In the display data storage area 433, the screen display data to be displayed by the output unit 3 is stored. The screen display data is data for displaying information on the output unit 3. In addition, in the shared area 434, data temporarily used when each process is executed by the control arithmetic unit 4 is stored. For example, the machining program number received by the input operation unit 2 is written into the shared area 434 of the storage unit 43 via the input control unit 41 and the data setting unit 42.

[0041] The output control unit 44 causes the screen display data stored in the display data storage area 433 of the storage unit 43 to be displayed on the output unit 3.

[0042] In the control arithmetic unit 4, the analysis processing unit 45, the control signal processing unit 46, and the interpolation processing unit 48 are connected to each other via the storage unit 43, and information is written and read via this storage unit 43. Hereinafter, when explaining the writing and reading of information between the analysis processing unit 45, the control signal processing unit 46, and the interpolation processing unit 48, the case of passing through the storage unit 43 may sometimes be omitted.

[0043] The analysis processing unit 45 is connected to the storage unit 43. The analysis processing unit 45 refers to the machining program number written in the shared area 434 of the storage unit 43. If the selected machining program number in the shared area 434 is received from the shared area 434, the selected machining program is read out from the machining program storage area 432, and analysis processing is performed on each program block (each line) of the machining program. The analysis processing unit 45 analyzes the S code as the spindle motor speed command, the G code as the command related to axis movement, etc., and the M code as the machine operation command. When the analysis processing for each line of the machining program is completed, the analysis processing unit 45 writes the analysis results of the S code, G code, M code, etc. to the shared area 434 of the storage unit 43.

[0044] In addition, when the S code is included in the machining program, the analysis processing unit 45 analyzes the S code, thereby obtaining the spindle speed, i.e., the spindle speed. Moreover, the analysis processing unit 45 writes the obtained spindle speed to the shared area 434 of the storage unit 43.

[0045] In addition, when the G code is included in the machining program, the analysis processing unit 45 analyzes the G code, thereby obtaining the tool feed condition, i.e., the movement condition, for moving the tool to the machining position. The movement condition is represented by the speeds in the X-axis and Z-axis directions for moving the turret and the positions in the X-axis and Z-axis directions for moving the turret. Moreover, the analysis processing unit 45 writes the obtained movement condition to the shared area 434 of the storage unit 43.

[0046] In addition, when the G code for vibration cutting is included in the machining program, the analysis processing unit 45 analyzes the G code, thereby obtaining the vibration condition including the frequency for vibrating the tool in vibration cutting, i.e., the vibration frequency, and the amplitude for vibrating the tool in vibration cutting. Moreover, the analysis processing unit 45 writes the obtained vibration condition to the shared area 434 of the storage unit 43.

[0047] The control signal processing unit 46 is connected to the PLC circuit unit 47 and receives signal information of relays and the like that actuate the machinery of the machine tool from the PLC circuit unit 47. The control signal processing unit 46 writes the received signal information into the shared area 434 of the storage unit 43. This signal information is referred to by the interpolation processing unit 48 during machining operation. In addition, if the control signal processing unit 46 outputs an auxiliary command to the shared area 434 through the analysis processing unit 45, it reads out the auxiliary command from the shared area 434 and sends it to the PLC circuit unit 47. The auxiliary command is a command other than the command that actuates the drive axis as a numerically controlled axis. The auxiliary command is, for example, an M code or a T code.

[0048] The interpolation processing unit 48 is connected to the storage unit 43 and the acceleration / deceleration processing unit 49. The interpolation processing unit 48 refers to the shared area 434 of the storage unit 43. If the movement condition and the vibration condition are written into the shared area 434 through the analysis processing unit 45, it reads out the movement condition and the vibration condition, and uses the read movement condition and vibration condition to generate an instruction vibration movement amount in the X-axis direction, that is, an X-axis instruction vibration movement amount, and also generates an instruction vibration movement amount in the Z-axis direction, that is, a Z-axis instruction vibration movement amount. In addition, the X-axis instruction vibration movement amount and the Z-axis instruction vibration movement amount are collectively referred to and abbreviated as the instruction vibration movement amount. The interpolation processing unit 48 writes the generated instruction vibration movement amount into the shared area 434 of the storage unit 43 and outputs it to the acceleration / deceleration processing unit 49. In addition, if the interpolation processing unit 48 obtains the FB vibration movement amount from the acceleration / deceleration processing unit 49, it writes the obtained FB vibration movement amount into the shared area 434 of the storage unit 43.

[0049] The acceleration / deceleration processing unit 49 is connected to the interpolation processing unit 48 and the axis data input / output unit 50. The acceleration / deceleration processing unit 49 transforms the instruction vibration movement amount output from the interpolation processing unit 48 into a movement instruction per unit time considering acceleration and deceleration according to a pre-specified acceleration / deceleration mode, and outputs the transformed movement instruction to the axis data input / output unit 50. In addition, the acceleration / deceleration processing unit 49 outputs the FB vibration movement amount output from the axis data input / output unit 50 to the interpolation processing unit 48.

[0050] The axis data input / output unit 50 is connected to the acceleration / deceleration processing unit 49 and the drive unit 7. The axis data input / output unit 50 outputs the movement instruction per unit time output from the acceleration / deceleration processing unit 49 to the drive unit 7. In addition, the axis data input / output unit 50 outputs the FB vibration movement amount output from the drive unit 7 to the acceleration / deceleration processing unit 49.

[0051] Next, an installation example of the braking device will be described. In the present embodiment, it is assumed that the braking device has an X-axis servomotor 71x that moves the tool in the X-axis direction, i.e., the vertical direction. In addition, the braking device of the X-axis servomotor 71x can be of an in-built type with respect to the X-axis servomotor 71x or an external type. Additionally, the servomotor having the braking device can be other than the X-axis servomotor 71x. For example, a servomotor that can be controlled in such a way that the moving direction of the tool includes a vertical component has a braking device.

[0052] Figure 2 is a diagram for explaining an installation example of the braking device according to the embodiment. According to Figure 2 , the X-axis servomotor 71x has a braking device 711x, a motor body 712x, and a shaft 713x. In addition, a detector 72x is arranged in the X-axis servomotor 71x. Additionally, Figure 2 the X-axis direction shown, for example, represents the vertical direction.

[0053] Additionally, according to Figure 2 , a feed mechanism 81x is connected to the X-axis servomotor 71x. The feed mechanism 81x has a coupling 811x, a ball screw 812x, a running part 813x, and a ball screw support part 814x. The coupling 811x has a function of connecting the X-axis servomotor 71x and the feed mechanism 81x. The ball screw 812x is arranged, for example, in the X-axis direction and can rotate about the axis of the X-axis via the coupling 811x by the rotation of the X-axis servomotor 71x. The running part 813x can move in the direction along the X-axis, for example, in the up-and-down direction along the vertical direction, by the rotation of the ball screw 812x.

[0054] When the machine tool is emergently stopped due to an emergency stop or the like, the braking device 711x operates to stop the rotation of the motor body 712x. At this time, the rotation of the ball screw 812x stops, and thus the up-and-down movement of the running part 813x also stops.

[0055] In addition, the braking device 711x may not be installed on the motor body 712x side but on the ball screw support part 814x. In addition, although the X-axis has been described as the vertical direction, in the case of a machine tool that performs machining in a state where the X-axis is set to be inclined with respect to the vertical direction, the braking device can also be installed on the servomotor connected to the machine tool. Additionally, in the case where it is set that another axis different from the X-axis includes the vertical direction, the braking device can be installed on the servomotor that controls the other axis. Specifically, for example, in the case where it is set that the Y-axis includes the vertical direction, the braking device can also be installed on the servomotor that controls the Y-axis.

[0056] Next, the operation of the braking device with a fastening hub will be described. Figure 3 This is a diagram for explaining the operation of the braking device according to the embodiment. In Figure 3 , with reference to an example of the schematic cross-sectional structure of the braking device 711x parallel to the X-axis direction, the operations when the brake is ON and when the brake is OFF will be described. In addition, in Figure 3 , structures other than those required for the description are omitted.

[0057] Figure 3 The braking device 711x shown has an external gear 7111x, an internal gear 7112x, a friction plate 7113x, a fixing plate 7114x, a pressing plate 7115x, a housing 7116x, an electromagnetic coil 7117x, and a spring 7118x. The external gear 7111x and the internal gear 7112x are an example of the fastening hub in the technical solution.

[0058] The external gear 7111x meshes with the internal gear 7112x. Hereinafter, the specific relationship between the external gear 7111x and the internal gear 7112x will be described using Figure 4 . Figure 4 This is a diagram for explaining an example of the structure of the fastening hub of the braking device according to the embodiment.

[0059] According to Figure 4 , for example, a through hole is formed in the external gear 7111x, and a shaft 713x is inserted and fixed through the through hole. The external gear 7111x rotates synchronously with the rotation of the shaft 713x around the axis of the shaft 713x.

[0060] The external gear 7111x has a plurality of external teeth 7119x along its outer circumference. In addition, the internal gear 7112x has a plurality of internal teeth 7120x along its inner circumference. When using the braking device 711x, the external gear 7111x and the internal gear 7112x are arranged in a positional relationship such that Figure 4 the plurality of external teeth 7119x and the plurality of internal teeth 7120x shown mesh. At this time, the internal gear 7112x is arranged so as to be movable relative to the external gear 7111x in the X-axis direction. Moreover, when the brake is OFF, the internal gear 7112x rotates synchronously with the rotation of the external gear 7111x.

[0061] In addition, a backlash is preset between the external gear 7111x and the internal gear 7112x. The backlash is a gap intentionally set at the meshing part of the gears. For example, from the viewpoints of the operation of the pressing plate 7115x, the brake specifications, and the assemblability, etc., an optimal value is set. The unit representing the backlash is, for example, "minute". "Minute" is a unit representing the angular size that is one-sixtieth of "degree" or "°". In addition, in the present embodiment, "°" is used as the unit representing the backlash for explanation.

[0062] Return Figure 3 , the friction plate 7113x is connected to the internal gear 7112x. The friction plate 7113x rotates synchronously with the rotation of the internal gear 7112x. The fixing plate 7114x has, for example, a function of restricting the movement of the friction plate 7113x in the direction of separating from the motor main body 712x when switching from brake OFF to brake ON.

[0063] When Figure 3 , when the brake is OFF, the electromagnetic coil 7117x is excited. That is, an electric current flows in the electromagnetic coil 7117x. At this time, an electromagnetic force greater than the elastic force of the spring 7118x is generated, and the pressing plate 7115x is pulled by the electromagnetic coil and moves toward the motor main body 712x side. As a result, the friction plate 7113x is disposed at a position separated from the fixing plate 7114x and the housing 7116x. At this time, there is no friction between the friction plate 7113x and the fixing plate 7114x and the housing 7116x, and the rotation is not restricted. Therefore, the external gear 7111x, the internal gear 7112x, and the friction plate 7113x can rotate in accordance with the rotation of the shaft 713x.

[0064] When Figure 3 , when the brake is ON, the current flowing in the electromagnetic coil 7117x stops and the electromagnetic force disappears. Due to the elastic force of the spring 7118x, the pressing plate 7115x moves in the direction of separating from the motor main body 712x. As a result, the friction plate 7113x abuts against both the pressing plate 7115x and the fixing plate 7114x and is in a clamped state, and the rotation of the friction plate 7113x is stopped by the frictional force. Therefore, the internal gear 7112x connected to the friction plate 7113x is stopped, and the rotation of the external gear 7111x and the shaft 713x as the motor shaft stops via the gears.

[0065] In addition, when the brake is ON, immediately after the X-axis servo motor 71x stops due to an emergency stop or the like, Figure 2 the shown operating part 813x stops after falling by the amount of the backlash provided between the external gear 7111x and the internal gear 7112x due to the action of gravity. As described above, in an emergency stop or the like, the fall of the operating part 813x can be prevented by the braking device 711x.

[0066] Here, in normal machining that is not vibration cutting, since the movement of the X-axis generated by machining is in one direction, for example Figure 4 only one of the two internal teeth 7120x of the internal gear 7112x that meshes with the external teeth 7119x of the external gear 7111x shown contacts the external teeth 7119x. However, in vibration cutting, minute vibrations accompanying vibration cutting are superimposed on the machining movement. Therefore, the external teeth 7119x of the external gear 7111x repeatedly contact both of the two internal teeth 7120x of the internal gear 7112x that meshes with the external teeth 7119x, for example, at the period of the minute vibrations accompanying vibration cutting. Therefore, the multiple external teeth 7119x of the external gear 7111x and the multiple internal teeth 7120x of the internal gear 7112x wear out much faster than in the case of only performing normal machining, and the life of the braking device expires quickly. Moreover, when the servo motor is continued to be used in the situation where the life of the braking device has expired, in an emergency stop or the like, for example, there is also a possibility that the rotating part 813x of the X-axis servo motor 71x drops by a value greater than or equal to the assumed value and collides with other mechanical structures, resulting in a failure. Therefore, replacement of the braking device is required. As described above, in the numerical control device that causes a machine tool to perform vibration cutting, the influence of wear caused by vibration cutting on the fastening hubs of the braking device 711x, that is, the external gear 7111x and the internal gear 7112x, becomes larger than the wear caused by the braking action. In addition, the minute vibrations accompanying vibration cutting are vibrations based on the vibration conditions for vibrating the cutting tool in vibration cutting, and are, for example, vibrations transmitted to the braking device 711x during the execution of vibration cutting.

[0067] Return Figure 1 , the interpolation processing unit 48 according to the present embodiment estimates the deterioration of the braking device based on the execution time of vibration cutting. Specifically, the interpolation processing unit 48 includes a measurement unit 481, an estimation unit 482, a change unit 483, a waveform generation unit 484, and a vibration movement amount generation unit 485.

[0068] The measurement unit 481 measures the execution time of vibration cutting. Specifically, the measurement unit 481 stores, for example, the cumulative value of the time for executing vibration cutting in one braking device. In addition, the measurement unit 481 determines whether the cumulative value of the execution time of vibration cutting is greater than or equal to a specified value.

[0069] The estimation unit 482 estimates the deterioration of the braking device 711x based on the number of vibrations of the micro-vibrations accompanying the vibration cutting. For example, the estimation unit 482 estimates the deterioration of the braking device 711x based on the execution time of the vibration cutting measured by the measurement unit 481 and the vibration frequency of the vibration cutting. The vibration frequency of the vibration cutting is, for example, the frequency set to generate micro-vibrations during the vibration cutting. The number of vibrations of the micro-vibrations accompanying the vibration cutting can be calculated based on the execution time of the vibration cutting and the vibration frequency of the vibration cutting. In addition, the estimation unit 482 can count the number of vibrations based on the basic waveform of the vibration, that is, the vibration waveform, generated by the waveform generation unit 484, and by accumulating the number of vibrations, set it as the number of vibrations of the micro-vibrations accompanying the vibration cutting.

[0070] Specifically, the estimation unit 482 refers to the deterioration progress information indicating the relationship between the execution time of the vibration cutting and the progress of the deterioration of the braking device, and estimates the deterioration of the braking device 711x. At this time, the deterioration progress information also includes information related to the vibration frequency of the vibration cutting that is a prerequisite for the vibration cutting. The deterioration execution information indicates the degree of progress that the longer the execution time of the vibration cutting, the more the deterioration of the braking device progresses. The deterioration progress information is, for example, information indicating the relationship between the execution time of the vibration cutting and the amount of wear in the fastening hub of the braking device, that is, information indicating that the longer the execution time of the vibration cutting, the more the wear in the fastening hub of the braking device progresses. The amount of wear in the fastening hub is, for example, the amount of wear that occurs between the external gear 7111x and the internal gear 7112x. This amount of wear is identified, for example, by the value of the backlash between the external gear 7111x and the internal gear 7112x.

[0071] In addition, the information indicating the relationship between the execution time of the vibration cutting and the amount of wear in the fastening hub of the braking device is, for example, information based on measured values obtained in advance from a durability test on the vibration cutting time for a braking device having the same type or a similar mechanical structure as the braking device 711x. Specifically, it is information based on the results of measuring the backlash of the fastening hub of the braking device at multiple times along the execution time of the vibration cutting. In addition, the braking device used in the durability test can also be a braking device of the same type as the braking device 711x.

[0072] In addition, the vibration frequency that is a prerequisite for measurement is, for example, an average of 166.7 Hz. The average of 166.7 Hz is achieved, for example, by designating a vibration frequency of 166.7 Hz, at least one vibration frequency less than 166.7 Hz, and at least one vibration frequency greater than 166.7 Hz, and repeatedly performing vibration cutting step by step so that the average vibration frequency of the vibration cutting performed within a specified time becomes 166.7 Hz. In addition, the measurement may be performed in a state where the vibration frequency that is a prerequisite for measurement is fixed to a specified value, such as 166.7 Hz. Further, the vibration frequency that is a prerequisite for measurement may not be included in the deterioration progress information. In this case, the estimation unit 482 may also refer to the deterioration progress information and the vibration frequency that is a prerequisite for measurement associated with the deterioration progress information.

[0073] Based on the estimation result of deterioration estimated by the estimation unit 482, the change unit 483 changes the vibration conditions of the vibration cutting. Specifically, the change unit 483 changes at least one of the number of vibrations (times) per revolution of the main shaft and the main shaft rotation speed (r / min), for example, so as to extend the life of the braking device 711x, that is, so as to slow down the progress of deterioration of the braking device 711x. Thereby, the vibration frequency (Hz) of the micro-vibration accompanying the vibration cutting is changed. More specifically, the change unit 483, for example, reduces at least one of the number of vibrations (times) per revolution of the main shaft and the main shaft rotation speed (r / min) compared with before the change, so as to make the vibration frequency (Hz) of the micro-vibration accompanying the vibration cutting smaller.

[0074] Based on the information obtained from the analysis processing unit 45, the waveform generation unit 484 generates a basic waveform of vibration, that is, a vibration waveform. When the change unit 483 changes the vibration conditions, the waveform generation unit 484 generates a vibration waveform based on the changed vibration conditions.

[0075] Using the vibration waveform generated by the waveform generation unit 484 and the movement path of the tool, the vibration movement amount generation unit 485 obtains, for example, the vibration movement amount in the X-axis. Specifically, for each vibration, the vibration movement amount generation unit 485 obtains a vibration forward position obtained by adding the amplitude of the vibration waveform to the movement path of the tool and a vibration backward position obtained by subtracting the amplitude of the vibration waveform from the movement path of the tool, and generates the vibration movement amount in the X-axis.

[0076] The vibration movement amount generated by the vibration movement amount generation unit 485 is sent to the drive unit 7 via the acceleration / deceleration processing unit 49 and the axis data input / output unit 50. Based on the vibration movement amount sent from the vibration movement amount generation unit 485, the drive unit 7 controls, for example, the X-axis servo motor 71x, thereby performing vibration cutting.

[0077] Regarding the processing executed by the numerical control device 1 configured as described above, use Figure 5 and Figure 6 will be described. Figure 5 is a diagram showing an example of the processing executed by the numerical control device according to the embodiment. In addition, in the present embodiment, the vibration frequency of the vibration cutting before the change is set to 166.7 Hz. Further, the vibration frequency of the vibration cutting that is the premise of the information indicating the relationship between the execution time of the vibration cutting referred to by the estimation unit 482 and the amount of wear in the fastening hub of the braking device is set to an average of 166.7 Hz.

[0078] According to Figure 5 , if the vibration cutting process is started, the measurement unit 481 starts measuring the execution time of the vibration cutting (step S51). Specifically, for example, when the vibration cutting mode is ON, the measurement unit 481 starts measuring the execution time of the vibration cutting if it receives a cutting start command. If the vibration cutting process ends, the measurement unit 481 ends the measurement of the execution time of the vibration cutting. Specifically, for example, when the vibration cutting mode is ON, the measurement unit 481 ends the measurement of the execution time of the vibration cutting if it receives a cutting end command. At this time, the measurement unit 481 stores, as the cumulative time of the new execution time, the time measured in step S1 added to the cumulative time of the execution time measured in the past.

[0079] If the measurement unit 481 ends the measurement of the execution time of the vibration cutting, the estimation unit 482 estimates the deterioration of the braking device 711x based on the execution time of the vibration cutting measured by the measurement unit 481 and the vibration frequency of the vibration cutting (step S52). Specifically, for example, the estimation unit 482 refers to the deterioration progress information to estimate the deterioration of the braking device 711x. For example, the estimation unit 482 estimates the deterioration of the braking device 711x based on the information indicating the relationship between the execution time of the vibration cutting and the amount of wear in the fastening hub of the braking device.

[0080] Figure 6 is a diagram showing an example of the information indicating the relationship between the execution time of the vibration cutting according to the embodiment and the amount of wear in the fastening hub of the braking device. Regarding Figure 6 the information shown, the vibration frequency that is the premise of the measurement is set to an average of 166.7 Hz. According to Figure 6, it can be seen that as the execution time of the vibration cutting increases, the backlash, i.e., the backlash between the outer gear 7111x and the inner gear 7112x, increases. The estimation unit 482 refers to the information indicating the relationship between the execution time of the vibration cutting and the wear amount in the fastening hub, and obtains the backlash corresponding to the execution time of the vibration cutting measured by the measurement unit 481, thereby estimating the wear amount of the fastening hub of the braking device 711x. In addition, Figure 6 The graph shown is a graph showing the relationship between the execution time of the vibration cutting and the wear amount in the fastening hub of the braking device when the vibration cutting process is continued at an average of 166.7 Hz. At this time, the execution time of the vibration cutting and the number of vibrations of the micro-vibration accompanying the vibration cutting are in a substantially proportional relationship. Therefore, as the information for estimating the wear amount of the fastening hub of the braking device 711x, the estimation unit 482 can use the information on the relationship between the number of vibrations of the micro-vibration accompanying the vibration cutting calculated based on the average vibration frequency and the execution time of the vibration cutting and the wear amount in the fastening hub of the braking device.

[0081] In addition, the relationship between the execution time of the vibration cutting and the backlash changes according to conditions such as the shaft diameter of the servo motor, the ball screw diameter, and the inertia of the rotating part. Therefore, it is preferably measured in advance for each mechanical structure.

[0082] In Figure 5 , if the estimation unit 482 estimates the wear amount of the fastening hub of the braking device 711x, it determines whether the estimated wear amount is greater than or equal to the first threshold (step S53). In Figure 6 , the first threshold is, for example, Th1. This Th1 is set, for example, as the threshold value at which the braking device needs to be replaced.

[0083] In Figure 5 , when the estimation unit 482 determines that the estimated wear amount is greater than or equal to the first threshold (Yes in step S53), it outputs a warning screen to the output unit 3 via the output control unit 44 (step S54).

[0084] Figure 7 is a diagram showing an example of the display screen output by the numerical control device according to the embodiment. According to Figure 7 , a message prompting the replacement of the braking device 711x is displayed on the output unit 3. Specifically, in Figure 7 , the estimation unit 482 displays, via the output control unit 44, on the output unit 3, for example, a graph SL1 showing the relationship between the execution time of the vibration cutting and the backlash in the state where the braking device 711x is installed, and a marker M1 showing the combination of the execution time of the vibration cutting at the message output time and the value of the backlash corresponding to the execution time of the vibration cutting.

[0085] Here, Figure 7 the execution time of the vibration cutting indicated by the mark M1 shown is greater than or equal to T1. Additionally, Figure 7 the backlash value indicated by the mark M1 shown is greater than or equal to the first threshold Th1. Furthermore, the mark M1 is not limited to Figure 7 the star shown. The mark M1 can be circular, quadrilateral, or triangular, and can be any mark if it is a mark that can be recognized by other operators or maintenance personnel.

[0086] Additionally, according to Figure 7 , the estimation unit 482, via the output control unit 44, displays a message prompting the replacement of the brake device 711x, namely, "It is the replacement period of the brake device on the X-axis. It is recommended to replace the replacement brake device." on the output unit 3.

[0087] Thus, the operator or maintenance personnel can identify that the replacement period of the brake device has expired and can replace the replacement brake device for the target axis. Additionally, by displaying the message prompting replacement and the graphic side by side, the operator or maintenance personnel can intuitively grasp the situation.

[0088] Furthermore, in Figure 7 , the estimation unit 482 displays both the graphic display and the message prompting replacement, but it can also display only the message prompting replacement.

[0089] When the estimation unit 482 determines that the estimated wear amount is not greater than or equal to the first threshold (No in step S53), it determines whether the estimated wear amount is greater than or equal to the second threshold (step S55). In Figure 6 , the second threshold is, for example, Th2. This Th2 is, for example, set as a threshold indicating the period for changing the vibration conditions to extend the life of the brake device. Th2 is, for example, a value preset in the numerical control device during the design of the machine tool. Additionally, Th2 can be, for example, a value set by the operator according to the usage conditions and processing conditions of the machine tool.

[0090] In Figure 5 , when the estimation unit 482 determines that the estimated wear amount is greater than or equal to the second threshold (Yes in step S55), for example, it notifies the change unit 483 of the gist of calculating the extended life conditions for the brake device 711x. The change unit 483 that has received the notification of the gist of calculating the extended life conditions calculates the extended life conditions according to the specified conditions (step S56).

[0091] Figure 8 is a diagram showing the combination of the vibration conditions related to the embodiment. According to Figure 8, as items representing the operating conditions for vibration cutting control, i.e., vibration conditions, the number of vibrations per revolution of the main spindle (times), the main spindle rotation speed (r / min), and the vibration frequency (Hz) are shown. In addition, the vibration frequency is uniquely determined based on the number of vibrations per revolution of the main spindle and the main spindle rotation speed. Therefore, the changing unit 483 changes at least one of the number of vibrations per revolution of the main spindle and the main spindle rotation speed so as to extend the life of the braking device 711x.

[0092] Next, a specific example of the calculation of the life extension conditions will be described using Figure 8 . In addition, the vibration conditions before the change are as Figure 8 shown and are set to be "number of vibrations per revolution of the main spindle: 2.5 times", "main spindle rotation speed: 4000 r / min", and "vibration frequency: 166.7 Hz".

[0093] In Figure 8 , for example, the changing unit 483 does not change the number of vibrations per revolution of the main spindle and changes the main spindle rotation speed from 4000 r / min to 3428 r / min. As a result, the vibration frequency changes from 166.7 Hz to 142.9 Hz. In addition, for example, the changing unit 483 can also receive an input of a desired life extension time, perform an inverse calculation based on the input life extension time, and change at least one of the number of vibrations per revolution of the main spindle and the main spindle rotation speed.

[0094] Figure 9 is a schematic diagram showing an example of the vibration waveforms before and after the change of the vibration conditions according to the embodiment. In Figure 9 , for example, the vibration frequency before the change is 166.7 Hz, and the vibration frequency after the change is 142.9 Hz. At this time, Figure 9 the vibration period CT1 before the change shown is 6.0 ms, and the vibration period CT2 after the change is 7.0 ms. In Figure 9 , the vibration waveforms Cn of the nth period and the vibration waveform Cn+1 of the (n + 1)th period are shown respectively before and after the change of the vibration conditions. In addition, in Figure 9 , the regions for realizing chip breaking in vibration cutting are shown before and after the change of the vibration conditions, and the idle swing region S occurring between the nth period and the (n + 1)th period. The idle swing region S is, for example, a region where the tool makes an idle swing without cutting between the movement path of the tool and the workpiece, and is a region where the chips generated so far can be broken.

[0095] As Figure 9As shown, by changing the vibration conditions as described above, it is possible to generate an idle swing region S before and after the change and reduce the vibration frequency. Thus, it is possible to calculate the vibration conditions that satisfy the conditions for vibration cutting, that is, the conditions for cutting while breaking the chips, and that can extend the life of the braking device 711x. In addition, Figure 9 As long as the vibration waveform shown is based on the measured value and satisfies the conditions for vibration cutting, it can be premised on either the vibration waveform based on the command value or the vibration waveform based on the FB value.

[0096] In Figure 5 , if the change unit 483 calculates the extended life condition in step S56, it changes the vibration conditions for vibration cutting based on the calculated extended life condition (step S57). Then, the waveform generation unit 484 generates a vibration waveform based on the changed vibration conditions and performs a vibration cutting process based on the generated vibration waveform. At this time, the vibration frequency in the vibration cutting process changes from 166.7 Hz to 142.9 Hz. Therefore, for example, Figure 4 the period during which the external teeth 7119x of the external gear 7111x shown abut against the two internal teeth 7120x of the internal gear 7112x meshing with the external gear 7111x becomes longer, and the number of abutments per unit time of performing vibration cutting can be reduced. Specifically, that is, the wear amount of the fastening hub of the braking device 711x per unit time of performing vibration cutting can be reduced. At this time, the changed life can be expected to be extended to about 166.7 Hz / 142.9 Hz = 1.17 times. As described above, the life of the braking device 711x can be extended.

[0097] In addition, the change unit 483 can prompt the calculated extended life condition to the operator or the maintenance staff. Figure 10 is a diagram showing another example of the display screen output by the numerical control device 1 according to the embodiment. According to Figure 10 , a message prompting the change of the vibration conditions in the X-axis servo motor 71x is displayed on the output unit 3.

[0098] Specifically, in Figure 10 , the change unit 483 displays, via the output control unit 44, for example, a graph showing the relationship between the execution time of vibration cutting in the braking device 711x and the backlash, and a mark M2 showing the combination of the execution time of vibration cutting at the message output time and the value of the backlash corresponding to the execution time of the vibration cutting on the output unit 3. In addition, in Figure 10In this case, the change unit 483 displays, via the output control unit 44, a presumed graph DL1 represented by a dotted line, for example. The presumed graph DL1 is a graph showing to what extent the life can be extended when the changed vibration conditions are set at the message output time.

[0099] Here, Figure 10 the execution time of the vibration cutting indicated by the shown mark M2 is greater than or equal to T2 and less than T1. Additionally, Figure 10 the backlash value indicated by the shown mark M2 is greater than or equal to the second threshold Th2 and less than the first threshold Th1. Furthermore, the mark M2 is not limited to Figure 10 the shown star shape. The mark M2 can be circular, quadrilateral, or triangular, and can be any mark as long as it can be recognized by other operators or maintenance personnel.

[0100] In addition, according to Figure 10 , the change unit 483 displays, via the output control unit 44, a message prompting a change in the vibration conditions in the X-axis servo motor 71x, that is, "If the vibration conditions of the vibration cutting are changed, the replacement period of the X-axis braking device can be extended by about 2 hours by the vibration cutting time. It can be extended by about 24 hours by the processing time during execution. Please arrange the replacement braking device in advance." on the output unit 3. At this time, the processing during execution at the display time is generally a processing that mixes normal processing and vibration cutting processing, and the ratio is, for example, 11:1. By displaying the time converted into the processing time during execution in accordance with the processing time of the vibration cutting, it becomes a more understandable display for the operator or maintenance personnel. In addition, according to Figure 10 , the change unit 483 displays, via the output control unit 44, for example, the remaining life as "12 hours remaining" when the vibration conditions are not changed. In addition, according to Figure 10 , the change unit 483 displays, via the output control unit 44, for example, the extended life when the vibration conditions are changed as "+2 hours" by the vibration cutting time.

[0101] Thereby, the operator or maintenance personnel can recognize the necessity of changing the vibration conditions of the vibration cutting and can determine whether to change the vibration conditions of the vibration cutting. Specifically, the operator or maintenance personnel will decide on Figure 10When the button B1 for changing the vibration cutting shown is pressed, the changed vibration conditions can thus be set for the numerical control device 1. In addition, when the operator or maintenance staff presses the button B2 that determines not to change the vibration conditions, the changed vibration conditions are not set for the numerical control device 1, and the vibration cutting process can be continued with the vibration conditions before the change. In addition, a message and a graph prompting the change of the vibration conditions are displayed side by side, so that the operator or maintenance staff can intuitively grasp the situation. In addition, when the button B1 is pressed, the life of the braking device 711x can be extended.

[0102] In addition, the operator or maintenance staff may change the vibration conditions of the vibration cutting not using the vibration conditions calculated by the change unit 483, but using the vibration conditions determined based on past experience such as machining conditions. Moreover, the change unit 483 may display, via the output control unit 44, a graph indicating the remaining life of the braking device 711x at the output unit 3, for example, based on the vibration conditions determined by the operator or maintenance staff. In addition, the change unit 483 may also display the change content of the vibration conditions via the output control unit 44. Specifically, the change unit 483 displays, for example, the vibration conditions before the change and the vibration conditions after the change at the output unit 3. In addition, the change unit 483 may also display a plurality of the vibration conditions after the change via the output control unit 44 for the operator or maintenance staff to select.

[0103] In addition, the case where one second threshold Th2 is set has been described, but it is not limited thereto. The second threshold Th2 may also be set to be greater than or equal to two. At this time, for example, in Figure 6 the graph shown, two second thresholds Th21 = 0.8 and Th22 = 1.0 are set, and the vibration conditions before the change are set to be Figure 8 "number of vibrations per revolution of the main shaft: 2.5 times", "main shaft rotational speed: 4000 r / min", and "vibration frequency: 166.7 Hz" shown. Moreover, for example, when the estimated value of the backlash is greater than or equal to Th21 and less than Th22, the change unit 483 prompts, via the output control unit 44, to display a screen for changing the vibration conditions to "number of vibrations per revolution of the main shaft: 2.5 times", "main shaft rotational speed: 3333 r / min", and "vibration frequency: 142.9 Hz" at the output unit 3. Then, when the estimated value of the backlash is greater than or equal to Th22 and less than Th1, the change unit 483 prompts, via the output control unit 44, to display a screen for changing the vibration conditions to "number of vibrations per revolution of the main shaft: 1.5 times", "main shaft rotational speed: 3333 r / min", and "vibration frequency: 83.3 Hz" at the output unit 3.

[0104] At this time, the change unit 483 changes the vibration frequency from 166.7 Hz to 142.9 Hz through the first change, and further reduces the vibration frequency from 142.9 Hz to 83.3 Hz through the second change, further extending the life. By setting a plurality of thresholds as described above and setting an opportunity to change the vibration condition that has been changed once again, it is possible to flexibly respond to cases where the operation policy or the like is changed midway, such as when the replacement period of the braking device is changed.

[0105] In Figure 5 the estimation unit 482 ends the process when it determines that the estimated wear amount is not greater than or equal to the second threshold (No in step S55).

[0106] According to the above embodiment, the control arithmetic unit 4 of the numerical control device 1 that controls the servo motor and the braking device that applies braking to the servo motor to make the machine tool perform vibration cutting has an estimation unit 482 that estimates the deterioration of the braking device 711x based on the number of vibrations of the micro-vibrations accompanying vibration cutting.

[0107] Thus, for example, the operator or maintenance personnel can refer to the estimation result of the deterioration estimated by the estimation unit 482, and thus can grasp in advance the replacement period of the braking device 711x and the like, and appropriately respond before problems such as occurrence or failure occur.

[0108] Therefore, according to the present embodiment, it is possible to grasp the deterioration of the braking device of the servo motor caused by vibration cutting.

[0109] In addition, in Figure 6 it has been described that the threshold Th1 is about 1.2 and the threshold Th2 is about 1.0, but it is not limited thereto. For example, depending on the mechanical structure, specifically, depending on the shape and size of the gear constituting the fastening hub and the like, the progress of wear of the fastening hub is different. Therefore, the thresholds Th1 and Th2 are preferably set to optimal values according to the mechanical structure.

[0110] In addition, Figure 6 it has been described by taking the case where the vibration frequency on the premise of being the graph shown is 166.7 Hz on average as an example, but it is not limited thereto. For example, using information representing the relationship between the execution time of vibration cutting on the premise of a smaller vibration frequency, such as 30.3 Hz on average, and the wear amount in the fastening hub, the same control can be performed and the same effect can be obtained.

[0111] Modification example.

[0112] As described above, the embodiments of the present invention have been described. However, when implementing the present invention, various modifications and applications related to various modes can be made. In the above embodiments, the case where the vibration conditions are changed or the estimation results are output to the operator or the like based on the estimation results of the deterioration estimated by the estimation unit 482 has been described. In a modified example, the case where the vibration conditions are changed or the estimation results are output to the operator or the like based on the measurement results obtained by actually performing a braking test on the basis of the estimation results of the deterioration estimated by the estimation unit 482 is described.

[0113] Figure 11 FIG. is a diagram showing a structural example of the numerical control device 1A related to the modified example.

[0114] The numerical control device 1A includes an input operation unit 2, an output unit 3, and a control arithmetic unit 4A. In addition, in Figure 11 , for example, a drive unit 7 as a component of a machine tool is shown. In addition, the drive unit 7 may also be an element independent of the machine tool.

[0115] The control arithmetic unit 4A related to the modified example includes an input control unit 41, a data setting unit 42, a storage unit 43, an output control unit 44, an analysis processing unit 45, a control signal processing unit 46, a PLC circuit unit 47, an interpolation processing unit 48A, a feed rate control processing unit 49, an axis data input / output unit 50, and a test unit 51.

[0116] Regarding the input control unit 41, the data setting unit 42, the storage unit 43, the output control unit 44, the analysis processing unit 45, the control signal processing unit 46, the PLC circuit unit 47, the feed rate control processing unit 49, and the axis data input / output unit 50, since they are the same as those in the above embodiments, the description thereof is omitted.

[0117] The interpolation processing unit 48A related to the modified example includes a measurement unit 481, an estimation unit 482A, a change unit 483, a waveform generation unit 484, and a vibration movement amount generation unit 485. Regarding the measurement unit 481, the change unit 483, the waveform generation unit 484, and the vibration movement amount generation unit 485, since they are the same as those in the above embodiments, the description thereof is omitted.

[0118] The estimation unit 482A related to the modified example has a function of determining whether to perform a braking test based on the estimated wear amount in addition to the functions of the estimation unit 482 in the above embodiments.

[0119] The test unit 51 performs a braking test. For example, if the test unit 51 receives a notice to perform a braking test from the estimation unit 482 included in the interpolation processing unit 48, the test unit 51 performs a braking test. Specifically, the test unit 51 includes a test control unit 511 and a measurement unit 512.

[0120] The test control unit 511 controls the braking test. Specifically, if the test control unit 511 receives a notification to conduct a braking test from the estimation unit 482, it switches, for example, the brake of the braking device 711x of the X-axis servo motor 71x from the OFF state to the ON state. At this time, the test control unit 511, for example, after confirming that an instruction to stop the rotation of the X-axis servo motor 71x has been issued, switches the brake of the braking device 711x from the OFF state to the ON state.

[0121] The measurement unit 512 measures, for example, the backlash of the fastening hub of the braking device 711x. Specifically, the measurement unit 512 measures, for example, the size of the backlash provided between the external gear 7111x and the internal gear 7112x. The backlash increases corresponding to the execution time of the vibration cutting. Therefore, by measuring this backlash, it is possible to identify a more accurate degree of deterioration.

[0122] If the test control unit 511 switches the brake from the OFF state to the ON state, the measurement unit 512 calculates the difference between the value of the FB counter in the FB control of the detector 72x at the moment when the instruction that the brake is ON is issued and the value of the FB counter at the moment when the counter value does not change, that is, when the rotation of the X-axis servo motor 71x completely stops after the brake is set to ON. The value of the FB counter is sent to the measurement unit 512, for example, from the detector 72x via the X-axis servo control unit 73x, the axis data input / output unit 50, the acceleration / deceleration processing unit 49, and the interpolation processing unit 48.

[0123] The measurement unit 512 divides the calculated difference value by the value of the FB counter per one rotation, thereby calculating the rotation angle of the fastening hub when braking is applied to the X-axis servo motor 71x as the backlash. The measurement unit 512 sends the calculated backlash value to, for example, the estimation unit 482A.

[0124] In addition, the calculated backlash value may sometimes vary depending on the relative positional relationship between the external teeth 7119x of the external gear 7111x and the internal teeth 7120x of the internal gear 7112x at the moment when the brake in the X-axis servo motor 71x is set to ON. Therefore, the test unit 51 preferably performs the braking test multiple times, and calculates the average value or the maximum value of the backlash values calculated for each test as the new backlash value. In addition, when the gear ratio between the gear on the motor shaft side and the gear on the braking device side meshing therewith is not 1:1, it is preferable to calculate the backlash considering the gear ratio.

[0125] Regarding the processing executed by the numerical control device 1A configured as described above, use Figure 12 andFigure 6 will be described. Figure 12 It is a diagram showing an example of the processing executed by the numerical control device 1A according to the modified example.

[0126] In Figure 12 , step S121 and step S122 are the same as Figure 5 the steps S51 and S52 shown.

[0127] In Figure 12 , if the estimation unit 482A estimates the wear amount of the fastening hub of the braking device 711x, it determines whether the estimated wear amount is greater than or equal to the second threshold (step S123). Here, the second threshold is, for example, Figure 6 Th2 shown.

[0128] In Figure 12 , when the estimation unit 482A determines that the estimated wear amount is greater than or equal to the second threshold (Yes in step S123), for example, it notifies the test unit 51 of the intention to perform a braking test. The test unit 51 that has received the notification from the estimation unit 482A performs a braking test (step S124).

[0129] Specifically, if the test control unit 511 receives a notification of the intention to perform a braking test from the estimation unit 482, it switches the brake of the braking device 711x of the X-axis servo motor 71x from the OFF state to the ON state, for example.

[0130] If the measurement unit 512 switches the brake from the OFF state to the ON state through the test control unit 511, it calculates the difference between the value of the FB counter in the FB control of the detector 72x at the moment when the brake is set to ON and the value of the FB counter at the moment when the rotation of the X-axis servo motor 71x stops with the brake set to ON. The measurement unit 512 divides the calculated difference value by the value of the FB counter per rotation, thereby calculating the rotation angle of the fastening hub when braking is applied to the X-axis servo motor 71x as the backlash. The measurement unit 512 sends the calculated backlash value as the measurement value obtained through the braking test to the estimation unit 482A, for example.

[0131] In Figure 12 , if the estimation unit 482A receives the measurement value obtained through the braking test from the measurement unit 512, it determines whether the received measurement value obtained through the braking test is greater than or equal to the first threshold (step S125). Here, the first threshold is, for example, Figure 6 Th1 shown.

[0132] In Figure 12In this case, when the determination unit 482A determines that the measured value obtained through the braking test is greater than or equal to the first threshold value (Yes in step S125), via the output control unit 44, a warning screen is output to the output unit 3, for example (step S126). In addition, the output method is the same as that in the above-described embodiment.

[0133] When the determination unit 482A determines that the measured value obtained through the braking test is not greater than or equal to the first threshold value (No in step S125), it determines whether the measured value obtained through the braking test is greater than or equal to the second threshold value (step S127). Here, the second threshold value is Th2 shown, for example, Figure 6 as follows.

[0134] In Figure 12 this case, when the determination unit 482A determines that the measured value obtained through the braking test is greater than or equal to the second threshold value (Yes in step S127), a notice to calculate the extended life conditions for the braking device 711x is given to the change unit 483, for example. The change unit 483 that has received the notice to calculate the extended life conditions calculates the extended life conditions according to the specified conditions (step S128). In addition, the calculation method of the extended life conditions is the same as that in the above-described embodiment.

[0135] In Figure 12 this case, step S129 is the same as step S57 shown in Figure 5 the following.

[0136] In Figure 12 this case, when the determination unit 482A determines that the estimated wear amount is not greater than or equal to the second threshold value (No in step S123), the process ends. Additionally, in Figure 12 this case, when the determination unit 482A determines that the measured value obtained through the braking test is not greater than or equal to the second threshold value (No in step S127), the process ends.

[0137] According to the modified example, a numerical control device 1A that controls a servo motor having a braking device to cause a machine tool to perform vibration cutting has a control arithmetic unit 4A that, based on the execution time of vibration cutting, for example, on the basis of a determination unit 482A that estimates the deterioration of the braking device 711x, also has a test unit 51 that performs a braking test on the braking device 711x. The control arithmetic unit 4A estimates the deterioration of the braking device based on the estimation result of the deterioration estimated from the execution time of vibration cutting and the result of the braking test. Thereby, the deterioration of the braking device 711x can be estimated with higher accuracy. In addition, since the braking test is only performed when specified conditions are satisfied, the stopping time of the machine obtained through the braking test can be minimized.

[0138] Other embodiments

[0139] In addition, in the above-described embodiment, the estimation unit 482 estimates the wear amount of the fastening hub of the braking device based on the execution time of the vibration cutting, and thereby estimates the deterioration of the braking device. However, the present invention is not limited thereto. The estimation unit 482 is a component of the braking device that deteriorates based on the execution time of the vibration cutting. As long as the deterioration can be identified, it can be any component. For example, the wear amount of the friction plate of the braking device can be estimated, and thereby the deterioration of the braking device can be estimated.

[0140] Figure 13 This is a diagram for explaining the operation of the braking device according to other embodiments. In Figure 13 reference is made to Figure 3 an example of the schematic cross-sectional structure parallel to the X-axis direction of the braking device 911x corresponding to the braking device 711x shown in the above-described embodiment, and the operations when the brake is ON and when the brake is OFF are explained. In addition, in Figure 3 structures other than those required for the explanation are omitted.

[0141] Figure 13 The braking device 911x shown in Figure 3 is a type of braking device that does not have a fastening hub, different from the type of braking device having a fastening hub shown in

[0142] In Figure 13 when the brake is OFF, the electromagnetic coil 9113x is excited. That is, a current flows through the electromagnetic coil 9113x. At this time, an electromagnetic force greater than the elastic force of the spring 9114x is generated, and the pressing plate 9112x is pulled by the electromagnetic coil and moves to the side opposite to the motor main body 712x. As a result, the friction plate 9111x is disposed at a position separated from the pressing plate 9112x. At this time, there is no friction between the friction plate 9111x and the pressing plate 9112x, and the rotation is not restricted. Therefore, the friction plate 9111x rotates in accordance with the rotation of the shaft 713x.

[0143] In Figure 13In this case, when the brake is ON, the current flowing through the electromagnetic coil 9113x stops and the electromagnetic force disappears. Due to the elastic force of the spring 9114x, the pressing plate 9112x moves in the direction approaching the motor body 712x. As a result, the friction plate 9111x abuts against the pressing plate 9112x, and the rotation of the friction plate 9111x is stopped by the frictional force. Therefore, the rotation of the shaft 713x to which the friction plate 9111x is fixed stops.

[0144] Here, in a numerical control device that causes a machine tool to perform vibration cutting, the friction plate 9111x of the brake device 911x is a component that is significantly affected by wear caused by vibration cutting compared to wear caused by the braking operation, similar to the fastening hub of the braking device 711x of the type having a fastening hub. Therefore, in the brake device 911x of the type not having a fastening hub, the wear amount of the friction plate 9111x of the brake device 911x can be estimated based on the execution time of vibration cutting, and thereby the deterioration of the brake device 911x can be estimated.

[0145] At this time, as information indicating the relationship between the execution time of vibration cutting using the X-axis servo motor 71x and the wear amount in the friction plate 9111x of the brake device 911x, the estimation unit 482 uses information indicating the relationship between the execution time of vibration cutting and the attraction time when the brake is OFF. The attraction time when the brake is OFF is, for example, the time required from when the current starts to flow through the electromagnetic coil 9113x shown until the pressing plate 9112x is pulled by the electromagnetic coil 9113x when the brake is OFF. As the wear of the friction plate 9111x progresses, the distance between the electromagnetic coil 9113x and the friction plate 9111x increases. If the distance between the electromagnetic coil 9113x and the friction plate 9111x increases, the attraction current required when the brake is OFF becomes larger. Moreover, in order to increase the attraction current to a specified value, a specified time is required, but since this specified value becomes larger, the time from when the brake OFF command is issued until the rotational speed of the motor reaches the target value becomes longer. Therefore, in the brake device 911x of the type not having a fastening hub, the deterioration of this friction plate 9111x becomes a bottleneck, and replacement of the brake device 911x is required. Figure 13

[0146] ​Information indicating the relationship between the execution time of vibration cutting and the attracting current when the brake is OFF, for example, is information based on measurement values obtained in advance from a durability test on the vibration cutting time for a brake device having the same mechanical structure. The estimation unit 482 estimates the deterioration of the brake device 911x based on information indicating the relationship between the execution time of the vibration cutting and the attracting time of the friction plate when the brake is OFF. The estimation unit 482 sets a first threshold value and a second threshold value to estimate the deterioration of the brake device 911x with respect to information indicating the relationship between the execution time of the vibration cutting and the attracting time when the brake is OFF, for example, in the same manner as the description in the above embodiment. In addition, the estimation unit 482 may perform a brake test after the estimation, in the same manner as the description of the modification example of the above embodiment.

[0147] In addition, in the above embodiment, the numerical control device 1 is configured to include the input operation unit 2 and the output unit 3, but it is not limited thereto. Specifically, the input operation unit 2 or the output unit 3 may be externally connected to the numerical control device 1, and the numerical control device 1 may not include the input operation unit 2 or the output unit 3.

[0148] In addition, in the above embodiment, the numerical control device 1 vibrates the tool to perform vibration cutting, but it is not limited thereto. For example, the numerical control device 1 may also vibrate the workpiece to perform vibration cutting.

[0149] Here, the hardware structure of the control arithmetic unit 4 included in the numerical control device 1 and the control arithmetic unit 4A included in the numerical control device 1A will be described. Figure 14 This is a diagram showing an example of the hardware structure of the control arithmetic unit related to the embodiment and the modification example. In addition, since the control arithmetic units 4 and 4A have the same hardware structure, the hardware structure of the control arithmetic unit 4 will be described here.

[0150] The control arithmetic unit 4 can be implemented by Figure 14 the control circuit 100 shown, that is, the processor 101 and the memory 102. Examples of the processor 101 are a CPU (also referred to as a Central Processing Unit, a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, a processor, a DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration), etc. Examples of the memory 102 are a RAM (Random Access Memory) or a ROM (Read Only Memory), etc.

[0151] The control arithmetic unit 4 is implemented by the processor 101 reading and executing a program stored in the memory 102 for performing the operations of the control arithmetic unit 4. Additionally, this program can be said to cause the computer to execute the sequence or method of the control arithmetic unit 4. The memory 102 is also used as a temporary memory when the processor 101 performs various processes.

[0152] The program executed by the processor 101 can be a computer program product having a computer-readable and non-transitory recording medium containing a plurality of commands that can be executed by a computer for data processing. The program executed by the processor 101 causes the computer to perform data processing by a plurality of commands.

[0153] Alternatively, the control arithmetic unit 4 can be implemented by dedicated hardware. Additionally, regarding the functions of the control arithmetic unit 4, a part can be implemented by dedicated hardware and a part can be implemented by software or firmware.

[0154] Without departing from the broad spirit and scope of the present invention, various embodiments and modifications can be implemented. Additionally, the above embodiments are used to illustrate the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is not the embodiments but is shown by the claims. Moreover, various modifications implemented within the scope of the claims and within the meaning of equivalent inventions are considered to be within the scope of the present invention.

[0155] Industrial Applicability

[0156] According to the present invention, it is possible to provide a numerical control device capable of grasping the deterioration caused by vibration cutting of a braking device that applies braking to a servo motor.

[0157] Description of Reference Numerals

[0158] 1, 1A Numerical control device, 2 Input operation unit, 3 Output unit, 4, 4A Control arithmetic unit, 41 Input control unit, 42 Data setting unit, 43 Storage unit, 44 Output control unit, 45 Analysis processing unit, 46 Control signal processing unit, 47 PLC circuit unit, 48, 48A Interpolation processing unit, 481 Measurement unit, 482, 482A Estimation unit, 483 Change unit, 484 Waveform generation unit, 485 Vibration movement amount generation unit, 49 Acceleration / deceleration processing unit, 50 Axis data input / output unit, 51 Test unit, 511 Test control unit, 512 Measurement unit, 7 Drive unit, 71x X-axis servo motor, 72x Detector, 73x X-axis servo control unit, 711x Braking device, 7111x Outer gear, 7112x Inner gear, 7113x, 9111x Friction plate.

Claims

1. A numerical control device controls a servo motor and a braking device that applies braking to the servo motor, causing a machine tool to perform vibration cutting. The numerical control device has an estimation unit that estimates deterioration of the braking device based on the number of vibrations of minute vibrations accompanying the vibration cutting.

2. A numerical control device controls a servo motor and a braking device that applies braking to the servo motor, causing a machine tool to perform vibration cutting. The numerical control device has an estimation unit that estimates deterioration of the braking device based on the execution time of the vibration cutting and the vibration frequency of the vibration cutting.

3. The numerical control device according to claim 1 or 2, wherein the estimation unit estimates deterioration of the braking device with reference to deterioration progress information indicating the relationship between the execution time of the vibration cutting and the progress of deterioration of the braking device.

4. The numerical control device according to any one of claims 1 to 3, wherein the estimation unit estimates the amount of wear of a fastening hub included in the braking device.

5. The numerical control device according to any one of claims 1 to 3, wherein the estimation unit estimates the amount of wear of a friction plate included in the braking device.

6. The numerical control device according to any one of claims 1 to 5, wherein it further has a test unit that performs a braking test of the braking device, and the estimation unit estimates deterioration of the braking device based on the estimation result of the deterioration and the result of the braking test.

7. The numerical control device according to any one of claims 1 to 6, wherein it further has a change unit that changes the vibration conditions of the vibration cutting in such a manner as to slow down the progress of deterioration of the braking device based on the estimation result of the deterioration.

8. The numerical control device according to claim 7, wherein it further has a change unit that changes the vibration conditions of the vibration cutting in such a manner that the vibration frequency of the vibration cutting becomes smaller based on the estimation result of the deterioration.

9. The numerical control device according to any one of claims 1 to 8, wherein it further has an output control unit that outputs the estimation result of the deterioration.

10. The numerical control device according to claim 9, wherein the output control unit outputs the service life of the braking device based on the estimation result of the deterioration.

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