JPWO2020235106A1 - Numerical control device - Google Patents

Abstract

The numerical control device (1) according to the present invention is a numerical control device that controls the operation of a machine tool (2) that processes a workpiece with a tool, and independently and continuously controls the spindle rotation speed and the feed speed. An operating state representing the operating state of the identification motion generator (14) that generates the identification motion command to be changed, the control signal for controlling the machine tool generated based on the identification motion command, and the corresponding machine tool (2). The vibration state of the machine tool (2) based on the data acquisition unit (16) that synchronizes with the signal and outputs it as identification data and the identification data is either stable machining, chatter vibration, or forced vibration. Among the machining characteristic parameters representing the characteristics of the machining phenomenon between the tool and the work, the identifiable machining characteristic parameters are selected based on the discrimination results of the vibration determination unit (12) and the vibration determination unit (12). It is provided with an identification unit (13) that selects as a selection parameter and identifies the selection parameter using the identification data.

Description

The present invention relates to a numerical control device that controls a machine tool.

A machine tool is a processing device that performs removal processing, which is processing to remove unnecessary parts from a work by applying force or energy to the work using a tool. In particular, in cutting, which is one of the removal processes, the cutting edge of the tool is brought into contact with the work at a high speed to cause shear failure on the surface of the work and scrape off unnecessary parts of the work.

Cutting is a physical phenomenon in which the machining process and mechanical dynamics interact with each other. Therefore, in order to control the machining state, it is desirable to manage both at the same time. Here, the machining process represents a series of processes in which a tool cutting edge invades the work to generate chips and forms a machined surface. Mechanical dynamics represents the behavior of a mechanical structure when the structure constituting the machine is vibrated by vibration sources inside and outside the machine. In general, cutting is a phenomenon in which various physical phenomena including the above-mentioned machining process and mechanical dynamics influence each other in a complicated manner, so that integrated analysis is difficult. For this reason, at the production site, processing management according to the purpose is achieved by limiting the evaluation target.

As described above, since the machine dynamics and the machining process interact with each other during cutting, the state of the machine tool before or after machining differs from the state of the machine tool during machining. That is, the state of the machine tool during machining cannot be accurately estimated before or after machining. For this reason, it is desirable to use the information obtained during machining to identify mechanical dynamics and machining processes. By using the results of identifying machine dynamics and machining processes, workers at the production site can efficiently perform improvement work such as managing tool life, setting highly efficient machining conditions, and changing the design of fixing jigs. Can be done. This can be expected to improve productivity.

Patent Document 1 proposes the following method as a method for identifying parameters from information obtained by sequentially changing the processing conditions during actual processing. In the method described in Patent Document 1, the compliance spectrum is calculated from the displacement and the force generated when machining at a plurality of spindle rotation speeds, and the peculiarity of the tool is obtained from the peak obtained when the compliance spectra of each spindle rotation speed are combined. Calculate the frequency. In this method, the machine tool is made to perform a machining operation so as to change the spindle rotation speed stepwise during the single operation of each feed shaft or the combined operation of the feed shafts, and the displacement and force detection results during machining are used. Calculate the compliance spectrum.

Japanese Unexamined Patent Publication No. 2017-94463

However, in the method described in Patent Document 1, various compliance spectra are obtained by setting the depth of cut at which chatter vibration does not occur and changing the spindle rotation speed stepwise, and calculating the natural frequency. Therefore, the method described in Patent Document 1 has a problem that only the natural frequency can be identified and the machining characteristic parameters such as the specific cutting resistance cannot be identified. Further, in the method described in Patent Document 1, when identifying a parameter other than the natural frequency, it is necessary to perform another identification operation. Further, in the method described in Patent Document 1, since the spindle rotation speed is changed stepwise only to a plurality of predetermined stages, it takes time to acquire parameters corresponding to various spindle rotation speeds. ..

The present invention has been made in view of the above, and an object of the present invention is to obtain a numerical control device capable of efficiently identifying machining characteristic parameters in a short time.

In order to solve the above-mentioned problems and achieve the object, the present invention is a numerical control device having a spindle and a feed shaft and controlling the operation of a machine tool for machining a workpiece with a tool. It is provided with an identification motion generation unit that generates an identification motion command that changes the feed speed independently and continuously. In addition, this numerical control device synchronizes the control signal for controlling the machine tool generated based on the identification operation command with the operation state signal indicating the operation state of the machine tool operated based on the control signal. It is provided with a data acquisition unit that outputs data for identification, and a vibration determination unit that determines whether the vibration state of the machine tool is stable machining, forced vibration, or chatter vibration based on the identification data. .. Further, this numerical control device selects and identifies the identifiable machining characteristic parameter among the machining characteristic parameters representing the characteristics of the machining phenomenon between the tool and the work as the selection parameter based on the discrimination result of the vibration determination unit. It is provided with an identification unit for identifying selection parameters using the data for use.

The numerical control device according to the present invention has the effect of being able to efficiently identify machining characteristic parameters in a short time.

Block diagram showing a configuration example of the numerical control device according to the first embodiment The figure which shows the example of the pattern of the identification action command generated by the identification action generation part of Embodiment 1. The figure which shows the example of the pattern of the identification action command generated by the identification action generation part of Embodiment 1. The figure which shows the example of the pattern of the identification action command generated by the identification action generation part of Embodiment 1. In the first embodiment, a schematic view showing how a disturbance force is transmitted to the table when the work fixed to the table vibrates due to a cutting force. The figure which shows an example of the rotation angle of a tool in which a tool cutting edge comes into contact with a work in Embodiment 1. FIG. 1 is a diagram showing an example of a rotation angle of a tool in which the tool cutting edge does not come into contact with the work in the first embodiment. The figure which shows the state of cutting at the 1st cutting edge in the case of the 1st Embodiment, when the amount of deviation occurs between the center of a tool and the center of rotation of a spindle. The figure which shows the state of cutting at the 2nd cutting edge when the deviation amount occurs between the center of a tool and the center of rotation of a spindle in Embodiment 1. FIG. A flowchart showing an example of the identification processing procedure in the identification unit of the first embodiment when the vibration determination unit determines that the vibration is chattering. A flowchart showing an example of the operation of the numerical control device according to the first embodiment. The figure which shows the structural example of the processing circuit of Embodiment 1. Block diagram showing a configuration example of the numerical control device according to the second embodiment A flowchart showing an example of the operation of the numerical control device according to the second embodiment. Block diagram showing a configuration example of the numerical control device according to the third embodiment Block diagram showing a configuration example of the numerical control device according to the fourth embodiment

Hereinafter, the numerical control device according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a block diagram showing a configuration example of the numerical control device 1 according to the first embodiment of the present invention. The numerical control device 1 of the first embodiment controls the operation of the machine tool 2 by transmitting a control signal to the machine tool 2, and receives an operation state signal indicating the operation state of the machine tool 2 from a sensor (not shown).

The machine tool 2 includes a spindle and a feed shaft, and processes a workpiece with a tool. Specifically, the machine tool 2 cuts the work by operating at least one of the tool and the work. For example, the machine tool 2 includes a spindle that gives a rotary motion to the tool or work, and a feed shaft that is a servo shaft that gives a position to the tool or work. The main shaft and the feed shaft each include a motor.

The machine tool 2 includes a sensor that detects the operating state of the machine tool 2 and outputs the detection result as an operating state signal. The sensor included in the machine tool 2 includes a sensor capable of detecting vibration in at least one of a tool and a workpiece. Sensors capable of detecting vibration in at least one of the tool and the workpiece are, for example, a linear encoder and a current sensor provided in the machine tool 2 in advance for feedback control of each motor of the machine tool 2. The linear encoder detects the position of each axis of the machine tool 2, and the current sensor detects the motor current of the motor of each axis. Other examples of sensors include accelerometers, position sensors, force sensors or microphones. In the following, as an example, the sensors included in the machine tool 2 will be described as a linear encoder, a current sensor, and a force sensor. The force sensor is installed, for example, on a structure such as a table constituting the feed shaft or inside the structure. The installation position of the force sensor is not limited to this, and it is sufficient that the force sensor is installed at a position where the force between the tool and the work can be detected.

As shown in FIG. 1, the numerical control device 1 includes a correction unit 11, a vibration determination unit 12, an identification unit 13, an identification motion generation unit 14, a drive control unit 15, and a data acquisition unit 16. The operation of each part of the numerical control device 1 of the first embodiment will be described.

The identification motion generation unit 14 generates an identification motion command that independently and continuously changes the spindle rotation speed and the feed rate of the machine tool 2, and outputs the identification motion command to the drive control unit 15. The number of rotations of the spindle is the rotation speed of the spindle, and indicates how many times the spindle rotates per unit time. The identification operation is a control signal and an operation state signal for the drive control unit 15 and the machine tool 2 in order to acquire identification data which is data used when the identification unit 13 executes the identification process described later. It is an operation to generate each. The identification operation command is a command generated for the identification operation, and includes a command for the spindle speed and a command for the feed rate.

2 to 4 are diagrams showing an example of the pattern of the identification operation command generated by the identification operation generation unit 14 of the first embodiment. Hereinafter, the pattern of the identification operation command is also referred to as a command pattern. 2 to 4 show a command pattern in which the spindle rotation speed and the feed rate change continuously between the identification operation start time t1 and the identification operation end time t2. The horizontal axis of FIGS. 2 to 4 shows the time (time), the vertical axis shows the spindle rotation speed in the upper row, and the feed rate shows the feed rate in the lower row. Hereinafter, the spindle speed and the feed rate may be described as S and F, respectively.

Here, S0 is the reference spindle rotation speed which is the spindle rotation speed before the identification operation, and S1 is the maximum value of the spindle rotation speed during the identification operation. T1 is a time constant when accelerating from the state where the spindle rotation speed is S0 to the state where the spindle rotation speed is S1. T2 is a time constant when accelerating from the state where the feed rate is F0 to the state where the feed rate is F1. FIG. 2 is a command pattern in which the spindle speed and the feed rate are accelerated and decelerated separately. In the example shown in FIG. 2, the spindle rotation speed accelerates with the time constant T1 and then decelerates when the spindle rotation speed reaches S1. Then, when the spindle speed reaches S0 due to deceleration, S0 is maintained as it is. When the spindle speed becomes S0 due to deceleration, the feed speed accelerates until it reaches F1 with the time constant T2. After that, when the feed rate reaches F1, the feed rate is decelerated.

FIG. 3 shows a command pattern in which the feed speed accelerates after the spindle speed accelerates, then decelerates, and then the spindle speed decelerates. FIG. 4 shows a command pattern in which the spindle speed accelerates and then decelerates, and the feed rate repeats acceleration and deceleration while the spindle speed changes.

In addition, in FIGS. 2 to 4, S1 is set as the maximum value of the spindle rotation speed during the identification operation, and an example of changing the spindle rotation speed between S0 and S1 is shown. A command pattern that changes within the range of S0 to S2 may be generated by setting the minimum value S2 of the spindle rotation speed inside. Similarly, with respect to the feed rate, the minimum value F2 of the feed rate during the identification operation may be set, and a command pattern that changes between F0 and F2 may be generated.

Further, in FIGS. 2 to 4, a command pattern for accelerating / decelerating in a triangular wave shape is illustrated, but if the command pattern is such that the spindle rotation speed and the feed rate are continuously accelerated / decelerated, the identification operation generation unit 14 may give an arbitrary command. Patterns can be generated. For example, the identification motion generation unit 14 may generate a command pattern that changes in a sinusoidal shape or an S-shaped curve instead of the triangular wave.

In this way, the identification motion generation unit 14 can generate an identification motion including various combinations of the spindle rotation speed and the feed rate by independently changing the spindle rotation speed and the feed rate.

It is known that the magnitude of the cutting force, which is the force generated when a tool cuts a workpiece, mainly depends on the feed amount per blade, and the vibration cycle of the cutting force mainly depends on the spindle speed. There is. Therefore, in general, when changing the spindle speed and the feed rate, they are changed at the same ratio. As a result, the load applied to the tool cutting edge becomes constant, so that the magnitude of the cutting force generated by the tool 1 blade does not change. Since the identification motion generation unit 14 independently changes the spindle rotation speed and the feed rate, the magnitude and amplitude of the cutting force can be changed in various ways, and the machine tool 2 during the identification motion will be described later. Various vibration states can be generated.

The drive control unit 15 controls the machine tool 2 so that the spindle and the feed shaft of the machine tool 2 operate in the operation specified by the identification operation command based on the identification operation command generated by the identification operation generation unit 14. Generate a control signal to do so. Here, the control signal is a command for the spindle and the feed shaft of the machine tool 2, and includes at least one of a position command, a speed command, and a current command for each motor of the spindle and the feed shaft. The drive control unit 15 is based on the machining path and the reference spindle speed and the reference feed rate in the machining path when the identification motion command is not input from the identification motion generation unit 14, that is, during normal machining operation. Generates a control signal for the machine tool 2. Further, the drive control unit 15 acquires a correction signal from the correction unit 11 described later, corrects the control signal for the machine tool 2 based on the correction signal, and outputs the corrected control signal to the machine tool 2.

The drive control unit 15 is set in advance with a machining path, a reference spindle speed and a reference feed rate in this machining path. The machining path and the reference spindle speed and reference feed rate in this machining path may be given by a numerical control program. Even when the identification motion command is input from the identification motion generation unit 14, the drive control unit 15 changes only the spindle speed and the feed rate according to the identification motion command without changing the set machining path. Generate a control signal. The machine tool 2 includes a motor and a motor control device for each axis, and the motor control device controls the motor based on a control signal received from the drive control unit 15 and feedback signals such as position, speed, and motor current. do. The position and speed feedback signals are calculated based on the positions detected by the linear encoder, and the motor current feedback signals are calculated from the detection results by the current sensor. The feedback signals of position, speed, and motor current are also hereinafter also referred to as position feedback signal, speed feedback signal, and current feedback signal, respectively.

The data acquisition unit 16 synchronizes the control signal output from the drive control unit 15 with the operation state signal representing the operation state of the machine tool 2 operated based on the control signal, and outputs the data as identification data. Specifically, the data acquisition unit 16 uses the control signal output from the drive control unit 15 and the operation state signal output from the sensor of the machine tool 2 to temporally obtain the data included in each signal. It is synchronized and output as synchronization data to the vibration determination unit 12 and the identification unit 13. As described above, the operation state signal is a signal indicating the operation state of the machine tool 2, and includes a signal capable of detecting vibration in at least one of the tool and the work. Here, as described above, since it is assumed that the sensors include a linear encoder, a current sensor, and a force sensor, the data acquisition unit 16 is detected by the feedback signals and the force sensor of the positions, speeds, and currents of the spindle and the feed shaft. It is possible to acquire the force, torque, etc. as an operating status signal. The measured values such as force and torque detected by the force sensor are also referred to as force information below. Since the operation status signal is a signal generated after the machine tool receives the control signal, the operation status signal is delayed in time with respect to the corresponding control signal due to the influence of the time required for communication and the like. Therefore, the data acquisition unit 16 compensates for the time lag between the two signals by shifting the data included in the operation state signal or the data included in the control signal by a time corresponding to the difference such as the communication time. The data acquisition unit 16 collects the data compensated for the time lag, that is, the synchronized data as identification data, and outputs the data to the vibration determination unit 12 and the identification unit 13.

The vibration determination unit 12 uses the identification data to determine whether or not the machine tool 2 is vibrating, and if it is determined that the vibration is occurring, the vibration determination unit 12 determines the type of the vibration. The determination result is output to the identification unit 13. The details of the vibration determination unit 12 will be described below. The vibration when the vibration determination unit 12 determines whether or not the vibration is generated means a vibration having a larger amplitude than the vibration component caused by the cutting force of the tool and the work.

The determination of vibration generation performed by the vibration determination unit 12 is executed by a known means. For example, it is determined that vibration has occurred when the force or torque indicated by the force information output from the force sensor exceeds a predetermined amplitude in the time domain. The type of signal used for vibration determination is not limited to force information. For example, the vibration determination unit 12 may determine whether or not vibration is generated by using a current feedback signal included in an operating state signal. Further, the vibration determination unit 12 converts a signal used for determining whether or not vibration is generated into a signal in the frequency domain, and when the vibration component having the maximum amplitude in the frequency domain exceeds a predetermined amplitude. It may be determined that vibration has occurred in the frequency.

By the way, there are forced vibration and self-excited vibration in the vibration phenomenon, and chatter vibration is a kind of self-excited vibration. Forced vibration is a vibration phenomenon in which a cutting force acts as a vibration source and a structure existing in the vicinity of a tool or work is excited. Due to this property, it is known that the vibration frequency of forced vibration is an integral multiple of the basic cutting frequency. On the other hand, chatter vibration, which is self-excited vibration, is a vibration phenomenon that occurs when the system consisting of cutting force and displacement of the structure becomes unstable. Due to this property, it is known that the vibration frequency of chatter vibration is a non-integer multiple of the basic cutting frequency. In the above, the basic cutting frequency is a frequency obtained by multiplying the spindle rotation speed by the number of tool blades.

The vibration determination unit 12 determines the type of vibration when it is determined that vibration is occurring. Specifically, the vibration determination unit 12 determines whether the generated vibration is a forced vibration or a chatter vibration as a determination of the type of vibration. The determination of the type of vibration is performed based on whether or not the determined vibration frequency is an integral multiple of the basic cutting frequency. That is, if the vibration frequency is an integral multiple of the basic cutting frequency, the vibration determination unit 12 determines that it is a forced vibration, and if the frequency is a non-integer multiple of the basic cutting frequency, it determines that it is a chatter vibration.

When the vibration determination unit 12 determines that no vibration has occurred, the vibration determination unit 12 determines that the processing is stable. Stable machining is a machining state in which only vibration components caused by the cutting force of the tool and the work are generated, and is a machining state in which vibration near the natural frequency of the structure is not excited.

By constantly executing the above processing, the vibration determination unit 12 determines whether the identification data at each time is stable processing, forced vibration, or chatter vibration, and uses the determination result as the vibration determination result in the identification unit 13. Output to. That is, the vibration determination unit 12 determines which of the plurality of states of stable machining, forced vibration, and chatter vibration is the vibration state of the machine tool 2 based on the identification data.

The identification unit 13 selects an identifiable processing characteristic parameter from the processing characteristic parameters as a selection parameter based on the discrimination result of the vibration determination unit 12, and uses the identification data input from the data acquisition unit 16 to use the identification unit 13. Identify the selection parameters. Further, the identification unit 13 further selects an identifiable dynamic characteristic parameter among the dynamic characteristic parameters as a selection parameter based on the determination result of the vibration determination unit 12. Hereinafter, the selection parameter is also referred to as an identifiable parameter. The identification unit 13 outputs the result of the identification process to the correction unit 11. The identification process is executed using the identification data and the processing condition information. The processing condition information is information representing the processing conditions in the identification operation, and is information preset in the identification unit 13. The machining condition information includes, for example, a tool diameter, a number of tool blades, a tool twist angle, a tool axial depth of cut, a tool radial depth of cut, and a machining mode representing upcut or downcut.

In the following, an example in which the identification unit 13 identifies both the dynamic characteristic parameter and the processing characteristic parameter will be described, but the identification unit 13 identifies only one of the dynamic characteristic parameter and the processing characteristic parameter. May be good. For example, the identification unit 13 selects an identifiable processing characteristic parameter among the processing characteristic parameters as a selection parameter based on the discrimination result of the vibration determination unit 12, and identifies the selection parameter using the identification data. ..

Generally, the spindle speed and feed rate during machining are commanded by constant values. In this case, the identification unit 13 can acquire only the identification data when the machine is processed with a set of spindle speeds and feed rates. As described above, the identification data includes the operation state signal detected by the sensor of the machine tool 2, so that the identification unit 13 has the operation state signal when processed with a set of spindle speeds and feed rates. You can only get it. However, in the present embodiment, since the identification motion generation unit 14 generates a command for continuously changing the spindle speed and the feed rate, the identification unit 13 generates different combinations of spindle speeds and feeds at each time. It is possible to obtain an operating state signal when processing at a high speed.

Here, the dynamic characteristic parameter and the machining characteristic parameter will be described. The dynamic characteristic parameter is a parameter representing the characteristics of the dynamics model described later, and is a parameter representing the vibration characteristics of the machine tool 2. The dynamic characteristic parameters are, for example, the equivalent mass, the damping coefficient, and the natural frequency. On the other hand, the machining characteristic parameter is a parameter representing the characteristics of the machining process model described later, and is a parameter representing the characteristics of the machining phenomenon between the tool and the work. Machining characteristic parameters are, for example, specific cutting resistance, edge force, tool eccentricity, and tool wear width.

The dynamics model is a mathematical model that describes the dynamics of the mechanical structure, tools, and workpieces inside the machine tool 2. An example of the dynamics model will be described below. FIG. 5 is a schematic view showing how the disturbance force is transmitted to the table when the work fixed to the table vibrates due to the cutting force in the first embodiment. FIG. 5 shows an example in which the machine tool 2 performs milling by rotating the tool 33. In FIG. 5, it is premised that the work 32 is placed on the table 31 constituting the drive shaft, and the touring system 34 constituting the spindle holds the tool 33. Further, in FIG. 5, the relative displacement 35 indicates the relative displacement of the work tip with respect to the table 31 in the vibration direction, the cutting force 36 indicates the cutting force in the work 32, and the disturbance force 37 indicates the disturbance force transmitted to the table 31. Shown. The relationship between the cutting force 36, the disturbance force 37, and the relative displacement 35 at this time can be expressed by the following equation (1). The dynamics model shown in the equation (1) calculates the disturbance force 37 transmitted to the feed shaft through the mechanical structure including the tool 33 or the work 32 when the cutting force 36 is generated, and when the cutting force 36 is generated. This is a mathematical model for calculating the position deviation that occurs at each feed axis through the mechanical structure.

The dynamics model shown in the equation (1) is a model in which the work 32 on the table 31 is described as a one-degree-of-freedom vibration system, but the dynamics model is not limited to the above example. For example, it may be described as a multi-degree-of-freedom vibration system including a fixing portion for fixing the work 32 and a table 31. Further, a dynamics model for a tool-side structure including a tool 33, a touring system 34 and a spindle motor may be set. Further, a dynamics model may be set as a vibration system in which the work-side structure including the fixing portion for fixing the work 32 and the table 31 and the tool-side structure are combined.

A machining process model is a mathematical model that describes the cutting process between a tool and a workpiece. An example of the machining process model is shown in the following equation (2).

The above formula (2) is a formula for calculating the cutting force given to the work 32 by the tool 33 from the cutting thickness corresponding to the rotation angle of the tool 33 at each time. Here, the cutting thickness refers to the thickness at which the work 32 is cut when the tool cutting edge, which is the cutting edge of the tool 33, passes through the work 32. As shown in FIGS. 6 and 7, the cutting force is calculated as a value of zero or more when the tool cutting edge is at an angle in contact with the work 32, but when the tool cutting edge is at an angle not in contact with the work 32. Is calculated as zero. FIG. 6 is a diagram showing an example of the rotation angle of the tool 33 in which the tool cutting edge contacts the work 32 in the first embodiment, and FIG. 7 is an example of the rotation angle of the tool 33 in which the tool cutting edge does not contact the work 32. It is a figure which shows. That is, for each rotation angle or time of the tool 33, it is determined whether or not to contact the work based on the position deviation, and when the tool cutting edge comes into contact with the work 32, the cutting thickness is calculated and the tool cutting edge is the work. If it does not come into contact with 32, the cutting thickness is calculated as zero.

The cutting force in the three directions can be calculated by performing the calculation shown in the equation (2) in the three directions of the tangential direction, the radial direction, and the axial direction of the tool. In the machining process model, the cutting force in the tool reference coordinate system is obtained by multiplying the cutting force having the components in the above three directions by the rotation matrix corresponding to the rotation angle of the tool 33, which is the rotation angle of the tool 33. Is calculated. Equation (3) shows an example of coordinate transformation.

By executing the calculations shown in the above equations (2) and (3) for the number of tool cutting edges and integrating the calculation results, the cutting force finally generated by the entire tool can be calculated. The machining process model represented by the formula (2) calculates the cutting thickness based on the relative position between the tool cutting edge and the work 32 to be machined by the tool 33 and the tool rotation angle, and is based on the cutting thickness. This is a mathematical model for calculating the cutting force generated between the tool and the workpiece. The cutting thickness in the formula (2) can be calculated by the formula (4) using the feed amount per blade and the tool rotation angle.

As another example, the cut thickness can also be calculated using equation (5).

Equation (5) adds the amount of fluctuation calculated from the difference between the current tool displacement and the premachined surface, which is the machined surface generated by the tool edge one blade before, to the formula (4). Furthermore, it is a calculation formula of the cutting thickness by adding the correction amount according to each tool cutting edge. In the calculation shown in equation (5), of the displacement amount generated at the current tool cutting edge and the displacement amount generated at the tool cutting edge one or more blades before, the displacement amount affecting the machined surface shape and the current tool cutting edge The cutting thickness is corrected by the difference from the displacement amount generated in. That is, the cutting thickness affects the shape of the machined surface among the loci generated by the current tool cutting edge involved in cutting and the tool cutting edge one or more blades before the current tool cutting edge. It is calculated based on the difference from the trajectory of the cutting edge.

Here, the tool center displacement amount v is a displacement amount corresponding to a component in the direction from the tool center to the tool cutting edge in the relative displacement x of the equation (1). The pre-machined surface displacement w is the amount of displacement generated on the machined surface due to the relative displacement x during cutting by the tool cutting edge one or more blades before. The tool cutting edge one or more blades before is a tool cutting edge involved in cutting at a time earlier than the time based on the tool cutting edge involved in cutting. For example, in a tool having two blades, when the tool cutting edge currently being cut is the second blade, the tool cutting edge one blade before is the first blade before rotating 180 degrees, and the tool cutting edge two blades before is 360. The second blade before the degree rotation, and the tool cutting edge three blades before is the first blade before the 540 degree rotation. When the tool is displaced during cutting and the cutting edge temporarily separates from the work 32, the current tool cutting edge is not only the pre-machined surface generated by the tool cutting edge one cutting edge before, but also the tool cutting edge two or more cutting edges before. The generated pre-machined surface is also cut.

Further, in the calculation shown in the equation (5), the cutting thickness is corrected by the correction amount according to the tool cutting edge number, which is a number indicating the tool cutting edge, and the tool rotation angle. Here, the correction amount is introduced to correct the change in the cutting thickness due to cutting with a different turning radius for each tool cutting edge. The following are examples of cases where it is necessary to introduce a correction amount. For example, when wear, chipping, etc. occurs on a specific cutting edge, the turning radius of the tool cutting edge is shorter than that of other tool cutting edges, so a correction amount corresponding to the wear width, chipping width, etc. is added. As another example, in a tool with a replaceable cutting edge, if there is a mounting error of the tool cutting edge, a correction amount corresponding to the mounting error is added. As another example, when the spindle rotation center does not coincide with the tool center, that is, when the tool eccentricity exists, a correction amount corresponding to the tool eccentricity amount is added. The tool center is the center of the circumscribed circle of the tool.

The tool eccentricity is the cutting thickness corresponding to the increase or decrease in the turning radius of the tool cutting edge for each tool cutting edge when there is a deviation amount between the tool center and the spindle rotation center as shown in FIGS. 8 and 9. It is the amount to correct. FIG. 8 is a diagram showing a state of cutting at the first cutting edge when a deviation amount occurs between the tool center and the spindle rotation center in the first embodiment, and FIG. 9 is a diagram showing a state of cutting at the tool center and the spindle rotation. It is a figure which shows the state of cutting in the 2nd cutting edge when the deviation amount is generated from the center. The first cutting edge 43 and the second cutting edge 44 are cutting edges of the tool. In the examples shown in FIGS. 8 and 9, there is a gap between the tool center 41 and the spindle rotation center 42. In such a case, it is necessary to correct the cutting thickness with respect to the cutting thickness when there is no deviation, and the tool eccentricity indicates the correction amount at this time. That is, the amount of tool eccentricity according to the rotation angle of the tool 33 is added or subtracted from the cutting thickness. The case where the cutting thickness is corrected by the correction amount is not limited to the above case, and the correction amount may be appropriately changed according to the phenomenon generated at the tool cutting edge.

The machining process model is not limited to the equation (2). For example, using the equation (2), the value of the specific cutting resistance may be changed depending on whether the cutting speed is higher than the threshold value or lower than the threshold value. Further, a model in which a process damping force is added to the right side of the equation (2) may be used. Here, the process damping force is a force generated when the flank of the tool cutting edge comes into contact with the work. Process damping can be expressed, for example, as a value obtained by multiplying the flank contact area by the process damping coefficient. In this case, the process damping coefficient is one of the machining characteristic parameters.

As another example, a machining process model for a tool with a helix angle may be used. Specifically, the tool is divided into tools having a minute thickness in the axial direction, the cutting force of each divided small thickness tool is calculated, and the cutting force is integrated in the tool axial direction to obtain the final cutting force. May be used as a model for calculating. As yet another example, it may be a model for calculating the cutting thickness and the cutting force by finite element analysis.

Hereinafter, when the dynamics model is the equation (1) and the machining process model is the equation (2), the parameters that can be identified from the vibration determination result are determined, and the process of identifying the parameters will be described. Candidates for the identifiable parameters described below are the dynamic characteristic parameters such as equivalent mass, damping coefficient and natural frequency, and the machining characteristic parameters such as specific cutting resistance, edge force and tool eccentricity.

When the vibration determination unit 12 inputs a vibration determination result indicating whether it is stable processing, forced vibration, or chatter vibration as the vibration determination result, the identification unit 13 performs the following processing according to the vibration determination result. .. In rare cases, forced vibration and chatter vibration occur at the same time, but in such a case, it is determined that the vibration is chatter vibration and identification is performed.

[When the judgment result is stable processing]
The identification unit 13 selects the specific cutting resistance and the edge force, which are machining characteristic parameters, as the identifiable parameters. Further, the identification unit 13 identifies the specific cutting resistance and the edge force by the following processing. The identification unit 13 calculates the specific cutting resistance and the edge force according to the equations (2) to (4) using the force information output from the force sensor and the machining conditions recorded in advance in the identification unit 13. .. That is, the calculated value of the force in each axial direction calculated when the equations (2) and (4) are substituted into the equation (3) substantially matches the measured value of the force detected by the force sensor. , Calculate the specific cutting resistance and edge force in equation (2). As a method for calculating the specific cutting resistance and the edge force, a known optimization method or numerical simulation may be used. For example, the least squares method or the gradient method can be used.

[When the judgment result is forced vibration]
The identification unit 13 selects the damping coefficient and the natural frequency, which are the dynamic characteristic parameters, and the specific cutting resistance and the edge force, which are the machining characteristic parameters, as the identifiable parameters. Further, the identification unit 13 identifies the damping coefficient, the natural frequency, the specific cutting resistance, and the edge force by the following processing.

The identification unit 13 uses the force information output from the force sensor and the processing conditions recorded in advance in the identification unit 13 to obtain the damping coefficient, the natural frequency, and the ratio according to the equations (1) to (4). Identify cutting resistance and edge force. Specifically, the measured value of the force detected by the force sensor is substituted into _{f d} in the following equation (6) obtained by modifying the equation (1).

Furthermore, the calculated value of the axial force which is calculated when substituting equations (2) and (4) into equation (3) is substituted into f _c in the formula (6). At this time, since there is a combination of the damping coefficient and the natural frequency for which the equation (6) holds, and the specific cutting resistance and the edge force, the identification unit 13 has the damping coefficient, the natural frequency, and the ratio satisfying the equation (6). Calculate the combination of cutting resistance and edge force. Specifically, the identification unit 13 searches for the damping coefficient and the natural frequency, and the specific cutting resistance and the edge force by using the gradient method so that the error on both sides of the equation (6) is minimized. Alternatively, the damping coefficient and natural frequency, and the specific cutting resistance and edge force can be calculated by the least squares method.

[When the judgment result is chatter vibration]
The identification unit 13 selects the dynamic characteristic parameters such as equivalent mass, damping coefficient, and natural frequency, and the machining characteristic parameters such as specific cutting resistance, edge force, and tool eccentricity as identifiable parameters. Further, the identification unit 13 identifies the equivalent mass, the damping coefficient, the natural frequency, the specific cutting resistance, the edge force, and the tool eccentricity by the following processing.

The identification unit 13 uses the force information output from the force sensor and the processing conditions recorded in advance in the identification unit 13 according to the equations (1), (2), (3) and (5). , Equivalent mass, damping coefficient and natural frequency, and specific cutting resistance, edge force and tool eccentricity. Specifically, the equivalent mass, the damping coefficient, the natural frequency, the specific cutting resistance, the edge force, and the tool eccentricity can be identified according to the procedure shown in FIG.

FIG. 10 is a flowchart showing an example of the identification processing procedure in the identification unit 13 of the first embodiment when the vibration determination unit 12 determines that the vibration is chattering. First, in step S1, the identification unit 13 sets initial values for the set of parameters. The set of parameters at this time is a combination of the equivalent mass, the damping coefficient, and the natural frequency, which are the dynamic characteristic parameters, and the specific cutting resistance, the edge force, and the tool eccentricity, which are the machining characteristic parameters.

In step S2, the identification unit 13 calculates the displacement amount that simultaneously satisfies the dynamics model and the machining process model. For example, the displacement amount that simultaneously satisfies the equation (1), which is a dynamics model, and the equations (2) and (5), which are machining process models, is calculated. Here, the displacement amount is the relative displacement x in the equation (1) and v, w in the equation (5).

In step S3, the identification unit 13 calculates the disturbance force when the displacement amount is given to the dynamics model. _{For example, the identification unit 13 calculates the disturbance force f d} by giving the displacement amount calculated in step S2 to the equation (1) which is a dynamics model.

In step S4, the identification unit 13 determines whether or not the error between the measured value of the force detected by the force sensor and the calculated value of the force calculated in step S3 is equal to or less than the allowable value. If the error is equal to or less than the permissible value (step S4 Yes), the identification unit 13 sets the value of the set of parameters at that time as the identification result, and ends the identification process. When the error exceeds the permissible value (step S4 No), the identification unit 13 updates the value of the parameter set in step S5 and returns to the process of step S2.

As a method of updating the parameters in step S5, for example, a method of increasing or decreasing each parameter by a predetermined amount can be used. The identification process in the identification unit 13 when the vibration determination unit 12 determines that the vibration is chattering is not limited to the processes in steps S1 to S5 described above. For example, equations (1), (2), (3) and (5) may be combined and each parameter may be calculated using the method of least squares.

Returning to the description of FIG. 1, the correction unit 11 receives the dynamic characteristic parameter and the machining characteristic parameter, which are the identification results, from the identification unit 13, and based on the identification result, receives a correction signal for correcting the operation of the machine tool 2. Output to the drive control unit 15. Specifically, a simulation related to machine dynamics and a machining process is executed in the correction unit 11, and a combination of a spindle rotation speed and a feed rate at which the vibration amplitude of the tool cutting edge becomes equal to or less than a specified value is calculated. The correction unit 11 generates a correction signal for correcting the spindle rotation speed and the feed speed based on the calculated spindle rotation speed and feed speed, and outputs the correction signal to the drive control unit 15. Here, the specified value is a value predetermined in the correction unit 11 and is set so that the machining result satisfies the defined dimensional intersection. The target to be corrected may include the depth of cut in the tool axis direction or the tool radial direction in addition to the spindle speed and the feed rate.

An example of the operation of the numerical control device 1 of the first embodiment described above will be described with reference to FIG. FIG. 11 is a flowchart showing an example of the operation of the numerical control device 1 of the first embodiment. In step S11, the numerical control device 1 starts the identification operation. Specifically, the identification motion generation unit 14 generates an identification motion command, and the drive control unit 15 creates a control signal for the machine tool 2 so that the machine tool 2 executes the motion specified in the identification motion. Output to machine 2.

In step S12, the vibration determination unit 12 acquires identification data. Specifically, the data acquisition unit 16 acquires a control signal from the drive control unit 15, acquires an operation state signal from the sensor of the machine tool 2, and generates identification data in which the time lag between the two is compensated. Then, it is output to the vibration determination unit 12 and the identification unit 13.

In step S13, the vibration determination unit 12 determines the vibration state based on the identification data. Specifically, the vibration determination unit 12 determines whether or not vibration is generated based on the operation state signal of the identification data, and if it is determined that vibration is not generated, the vibration state is stabilized. It is determined that. Further, when the vibration determination unit 12 determines that vibration is occurring, it determines whether it is forced vibration or chatter vibration based on the frequency of vibration. The vibration determination unit 12 outputs the determination result of the vibration state to the identification unit 13 as the vibration determination result.

In step S14, the identification unit 13 selects an identifiable parameter based on the identification data and the vibration determination result. Specifically, the identification unit 13 selects a parameter that can be identified from the dynamic characteristic parameter and the processing characteristic parameter according to the vibration determination result.

In step S15, the identification unit 13 identifies the identifiable parameters selected in step S14 using the identification data. In step S16, the numerical control device 1 corrects the operation of the machine tool 2 based on the identification result after the end of the identification operation up to step S15, that is, in the normal machining operation. Specifically, the correction unit 11 generates a correction signal for correcting the operation of the machine tool 2 based on the identification result calculated by the identification unit 13, and outputs the correction signal to the drive control unit 15. The drive control unit 15 generates a control signal based on the machining path, the reference spindle speed and the reference feed rate in the machining path, and the correction signal, and outputs the control signal to the machine tool 2.

The numerical control device 1 can identify parameters by executing a series of processes from step S11 to step S15 every moment during machining. Further, after the identification operation, the processing in step S16 can improve the processing state by using the identification result.

Next, the hardware configuration of the numerical control device 1 will be described. Each part of the numerical control device 1 shown in FIG. 1 is realized by a processing circuit. The processing circuit may be a circuit including a processor or dedicated hardware.

When the processing circuit is a circuit including a processor, the processing circuit is, for example, the processing circuit having the configuration shown in FIG. FIG. 12 is a diagram showing a configuration example of the processing circuit of the first embodiment. The processing circuit 200 includes a processor 201 and a memory 202. When each part of the numerical control device 1 is realized by the processing circuit 200 shown in FIG. 12, these are realized by the processor 201 reading and executing the program stored in the memory 202. That is, when each part of the numerical control device 1 is realized by the processing circuit 200 shown in FIG. 12, these functions are realized by using a program which is software. The memory 202 is also used as a work area for the processor 201. The processor 201 is a CPU (Central Processing Unit) or the like. The memory 202 corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, a magnetic disk, or the like.

When the processing circuit that realizes each part of the numerical control device 1 is dedicated hardware, the processing circuit is, for example, FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit). Each part of the numerical control device 1 may be realized by combining a processing circuit including a processor and dedicated hardware. Each part of the numerical control device 1 may be realized by a plurality of processing circuits.

As described above, the numerical control device 1 of the first embodiment generates a command for continuously changing the speed with respect to the spindle and the feed shaft, and gives the command independently to the spindle and the feed shaft. Have the machine tool perform the identification action. Then, the numerical control device 1 of the first embodiment discriminates the vibration state of the machine tool 2 from the identification data collected in the identification operation, and identifies the process characteristic parameters that can be identified according to the discrimination result. As described above, the numerical control device 1 of the first embodiment can efficiently identify the machining characteristic parameters in a short time. Further, the numerical control device 1 of the first embodiment can also identify a dynamic characteristic parameter that can identify the vibration state according to the discrimination result. Further, since the numerical control device 1 of the first embodiment can reproduce a plurality of types of vibration states during one identification operation for the machine tool 2, it is short even if the operator does not change the machining conditions each time. Identification can be performed efficiently in time. Furthermore, by reproducing the chatter vibration state, the dynamic characteristic parameter and the machining characteristic parameter can be estimated at the same time. As a result, the numerical control device 1 of the first embodiment can correct the control signal for the machine tool based on the identification result, so that the machining can be continued without causing a machining defect. Further, if the spindle rotation speed is changed stepwise in a stepwise manner for identification, the peak value that is a candidate for the natural frequency can be searched only discretely. On the other hand, in the present embodiment, as described above, since the command for continuously changing the speed with respect to the spindle and the feed shaft is generated, the case where the spindle speed is changed stepwise in steps. More accurately, the dynamic characteristic parameter and the processing characteristic parameter can be identified.

The dynamics model and the machining process model are not limited to the above equations (1) and (2), and can be appropriately changed depending on the machine structure and the machining method. Therefore, the dynamic characteristic parameters are not limited to the equivalent mass, the damping coefficient, and the natural frequency, and similarly, the machining characteristic parameters are not limited to the specific cutting resistance, the edge force, and the tool eccentricity. Even if the dynamic characteristic parameter and the processing characteristic parameter are appropriately changed according to the dynamics model and the processing process model, the same effect as that of the first embodiment can be obtained.

Although the configuration in which one machine tool 2 is controlled by one numerical control device 1 is described in the first embodiment, two or more machine tools may be connected to the numerical control device 1. For example, a command to change the spindle rotation speed is generated for the first machine tool, a command to change the feed speed is generated for the second machine tool, and an operation command is issued to each machine tool at the same time. By giving, the effect is that the identification is completed in a shorter time than when the operation is performed by one machine tool. In the first embodiment, the machine tool 2 that performs milling by rotating a tool has been described, but the present invention can also be applied to a machine tool that performs turning by rotating a work.

In the first embodiment, the force is directly detected by the force sensor, but even if the force is indirectly estimated by using another sensor, the same effect as that of the first embodiment can be obtained. can. For example, the data acquisition unit 16 or the identification unit 13 can calculate the force by the following equation (7) using the reference motor current which is a motor current command and the position detected by the linear encoder.

As another example, the force can be calculated in the same way by using an accelerometer. In this case, the data acquisition unit 16 or the identification unit 13 can calculate the force by the following equation (8) using the acceleration detected by the acceleration sensor.

Equations (7) and (8) are formulas for calculating the force when the feed shaft is regarded as a single inertial body. You may. Further, a term for compensating for the frictional force may be added.

Embodiment 2.
FIG. 13 is a block diagram showing a configuration example of the numerical control device according to the second embodiment of the present invention. In the first embodiment, an example in which the identification process is performed from the control signal and the operating state signal during the execution of the identification operation once has been described. In the first embodiment, when chatter vibration does not occur during one identification operation, some of the dynamic characteristic parameters and the processing characteristic parameters cannot be identified. In the second embodiment, an example of modifying the identification operation when chatter vibration does not occur when the identification operation is executed will be described. Hereinafter, with respect to the components having the same functions as those in the first embodiment, the same reference numerals are used and duplicate description will be omitted. Hereinafter, the points different from those of the first embodiment will be mainly described.

As shown in FIG. 13, the numerical control device 1a is different from the first embodiment except that the identification unit 13a and the identification motion generation unit 14a are provided instead of the identification unit 13 and the identification motion generation unit 14 of the first embodiment. The same is true. The identification unit 13a and the identification motion generation unit 14a are realized by a processing circuit in the same manner as the identification unit 13 and the identification motion generation unit 14 of the first embodiment.

Similar to the identification unit 13 of the first embodiment, the identification unit 13a selects an identifiable parameter from the dynamic characteristic parameter and the processing characteristic parameter by using the vibration determination result input from the vibration determination unit 12. Further, the identification unit 13a executes an identification process for identifying the selected identifiable parameter based on the identification data input from the data acquisition unit 16 as in the identification unit 13 of the first embodiment. Then, the result of the identification process is output to the correction unit 11. The identification process is executed in the same manner as the identification unit 13 of the first embodiment by using the identification data and the processing condition information.

Further, in the identification unit 13a, at least one of the dynamic characteristic parameter and the processing characteristic parameter is preset as a parameter to be identified. The identification unit 13a outputs an identification operation correction signal to the identification operation generation unit 14a, which will be described later, when an unidentified parameter exists among the parameters to be identified after the identification process is performed one or more times. The identification operation correction signal is a signal indicating the existence of an unidentified dynamic characteristic parameter or processing characteristic parameter.

Similar to the identification motion generation unit 14 of the first embodiment, the identification motion generation unit 14a generates an identification motion command for changing the spindle speed and the feed rate of the machine tool, and outputs the identification motion command to the drive control unit 15. do.

Further, the identification motion generation unit 14a modifies the identification motion command pattern based on the identification motion correction signal output from the identification unit 13a. Similar to the identification unit 13, the identification unit 13a can identify the most types of parameters when chatter vibration occurs in the machine tool. Therefore, the identification motion generation unit 14a modifies the identification motion so that chatter vibration occurs in the process of the identification motion by changing the range in which the spindle rotation speed or the feed rate is changed. Specifically, the identification motion generation unit 14a changes at least one of the above-mentioned maximum value S1 and minimum value S2 of the spindle rotation speed, maximum value F1 and minimum value F2 of the feed rate at a predetermined ratio. Generate an identification action command pattern. Specifically, for example, the maximum value S1 and the minimum value of the spindle rotation speed are set so that at least one of the spindle rotation speed and the feed rate is in a range different from the range of change set in the previous identification operation. S2, at least one of the maximum value F1 and the minimum value F2 of the feed rate is changed.

An example of the operation of the numerical control device 1a according to the second embodiment described above will be described with reference to FIG. FIG. 14 is a flowchart showing an example of the operation of the numerical control device 1a according to the second embodiment. In step S21, the numerical control device 1a starts the identification operation. In the first step S21, the identification motion generation unit 14a generates the first identification motion command, and the drive control unit 15 sends a control signal to the machine tool so that the machine tool executes the motion specified in the identification motion. Output to the machine tool.

In steps S22 to S25, the same processing as in steps S12 to S15 of FIG. 11 described in the first embodiment is performed. In step S26, the identification unit 13a determines whether or not a predetermined parameter to be identified has been identified, and if the identification is completed (step S26 Yes), the process proceeds to step S28. If any of the predetermined parameters to be identified has not been identified (step S26 No), the numerical control device 1a modifies the identification operation command in step S27 and repeats the process from step S21. Specifically, in step S27, the identification unit 13a outputs the identification operation correction signal to the identification operation generation unit 14a, and the identification unit 13a changes the range of change of at least one of the shaft rotation speed and the feed rate. The identification operation command is modified, and the modified identification operation command is output to the drive control unit 15. In the second and subsequent steps S21, the drive control unit 15 generates a control signal for the machine tool 2 based on the modified identification operation command and outputs the control signal to the machine tool 2.

In step S28, the numerical control device 1a corrects the operation of the machine tool 2 based on the identification result. Specifically, similarly to the correction unit 11 of the first embodiment, the correction unit 11 generates a correction signal based on the identification result calculated by the identification unit 13a and outputs the drive control unit 15 after the identification operation is completed. .. The drive control unit 15 generates a control signal based on the machining path, the reference spindle speed and the reference feed rate in the machining path, and the correction signal, and outputs the control signal to the machine tool 2.

The numerical control device 1a repeatedly executes a series of processes from step S21 to step S27 during machining. That is, in the identification unit 13a, after the identification is performed using the identification data for the period corresponding to the identification operation command, among the identification target parameters that are set as the identification targets, the parameters that have not been identified are unidentified. If present, an identification motion correction signal instructing a change in the identification motion is generated and output to the identification motion generation unit 14a. Then, when the identification motion generation unit 14a receives the identification motion correction signal, the identification motion command is changed, and the data acquisition unit 16 is based on the control signal generated based on the changed identification motion command and the control signal. The operating state signal representing the operating state of the machine tool 2 that has been operated is synchronized and output as identification data to the vibration determination unit 12 and the identification unit 13a. Then, these operations are repeated until the identification of all the parameters set as the identification targets is completed. As a result, all the dynamic characteristic parameters and the processing characteristic parameters set as the identification target can be identified. Further, by the processing of step S28, the processing state can be improved by using the identification result. Although the processing flow for modifying the identification operation command after the completion of one identification operation has been described here, the processing flow for modifying the identification operation during the identification operation may be used.

As described above, the numerical control device 1a of the second embodiment corrects the identification operation and performs the identification operation again when there is an incompletely identified parameter among the predetermined parameters to be identified. implement. Therefore, the numerical control device 1a of the second embodiment modifies the identification operation and generates chatter vibration even if there is a parameter that cannot be identified by the command pattern of the initial identification operation, so that the identification is specified in advance. It has the effect of being able to identify all of the target parameters.

Embodiment 3.
FIG. 15 is a block diagram showing a configuration example of the numerical control device according to the third embodiment of the present invention. In the second embodiment, the identification operation was repeated until all the parameters to be identified, which were predetermined internally, were identified. In the third embodiment, an example in which the parameter to be identified can be set from the outside will be described. Hereinafter, with respect to the components having the same functions as those in the second embodiment, the same reference numerals are used and duplicate description will be omitted. Hereinafter, the points different from those of the second embodiment will be mainly described.

As shown in FIG. 15, in the numerical control device 1b of the third embodiment, an input unit 17 is added to the numerical control device 1a of the second embodiment. The input unit 17 can accept the input of the parameter to be identified from the outside. The input unit 17 can receive at least one input of a dynamic characteristic parameter and a processing characteristic parameter as parameters to be identified from, for example, an external device or an operator. The input unit 17 may be a communication circuit that communicates with an external device, an interface circuit of an external medium that reads data from an external medium, or an input means such as a keyboard or a mouse. .. Further, when the input unit 17 receives an input from an operator, display means such as a display and a monitor are also used as the input unit 17. The parameter to be identified may be input to the input unit 17 as a numerical control program, or may be interactively input to the input unit 17 by the operator. Further, the input unit 17 may accept the input of the parameter to be identified in the form of interactive programming. The input unit 17 outputs the received parameters to be identified to the identification unit 13a. Examples of cases in which the parameters to be identified are specified by the operator or from the outside include, for example, "when you want to remove a parameter already identified by another means from the identification target" (first case), and "high priority". A case such as "when you want to reduce the time required for identification by identifying only the identification target" (second case) is assumed. Therefore, assuming the first case, for example, in the menu list, the identified parameters are displayed so that the identified parameters can be distinguished by inputting the values obtained in the past identification in advance. This makes it easier to identify unidentified parameters. In addition, assuming the second case, by making it possible to select the parameter to be identified with a check box or the like, a display window is provided so that the estimated identification time changes each time a check is entered in the check box. , The operator can select the most parameters within the range where the identification time is within the allowable identification time. The form of interactive programming is not limited to these examples, and may be any method, but the operator can easily display the information to be considered for selection as described above. The parameters to be identified can be selected.

Similar to the identification unit 13a of the second embodiment, the identification unit 13a uses the parameters of the identification target input from the input unit 17 instead of the preset parameters of the identification target, and is the same as that of the second embodiment. Do the action. The identification unit 13a may be capable of performing both an operation using the preset parameters of the identification target and an operation using the parameters of the identification target input from the input unit 17. The identification unit 13a outputs the result of the identification process to the correction unit 11. The operation of the correction unit 11 is the same as that of the first embodiment. The operation of the correction unit 11 when the parameter to be identified is specified by the numerical control program is as follows. Numerical control programs generally describe information such as machining paths, spindle speeds, feed rates, and tool numbers. When the worker specifies the parameter to be identified from the numerical control program, the processing path for performing the identification operation and the parameter to be identified are specified in the numerical control program. When the identification by the identification unit 13a is completed, for example, the correction unit 11 has a specified value of the vibration amplitude of the tool cutting edge until the timing when the tool number is changed or the timing when the machining path for which another identification operation is set is machined. Continue to generate correction signals such as: The operation of the numerical control device 1b of the third embodiment other than the above is the same as the operation of the numerical control device 1a of the second embodiment.

As described above, the numerical control device 1b of the third embodiment modifies the identification operation when there is an unidentified parameter among the parameters of the identification target set by the input from the outside. Perform the identification operation again. Therefore, the same effect as that of the second embodiment can be obtained, and the parameter to be identified can be changed according to the request of the operator or the like.

Embodiment 4.
FIG. 16 is a block diagram showing a configuration example of the numerical control device according to the fourth embodiment of the present invention. In the third embodiment, a configuration in which the parameter to be identified can be set from the outside has been described. In the fourth embodiment, a configuration in which a command pattern for the identification operation can be set by input from the outside will be described. Hereinafter, with respect to the components having the same functions as those in the third embodiment, the same reference numerals are used and duplicate description will be omitted. Hereinafter, the points different from those of the third embodiment will be mainly described.

As shown in FIG. 16, the numerical control device 1c is the same as the numerical control device 1b of the third embodiment except that the identification motion generation unit 14b and the input unit 17a are provided instead of the identification motion generation unit 14a and the input unit 17. Is.

Similar to the input unit 17 of the third embodiment, the input unit 17a can receive the parameters to be identified from the outside, and outputs the received parameters of the identification target to the identification unit 13a. Further, the input unit 17a can accept the input of the command pattern information for determining the command pattern of the identification operation from the outside. The input unit 17a outputs the received command pattern information to the identification operation generation unit 14b. The command pattern information is, for example, information representing the spindle rotation speeds S0, S1, feed speeds F0, F1, and time constants T1 and T2 in FIGS. 2 to 4. That is, the command pattern information is information indicating a waveform with respect to the time of the spindle rotation speed and the feed speed when the spindle rotation speed and the feed speed are changed by the identification operation command. The command pattern information is input to the input unit 17a as a numerical control program or interactively, for example. Further, the command pattern information may be input in the form of interactive programming. The waveform or the information indicating the waveform shown in FIGS. 2 to 4 may be added to the command pattern information so that the waveform can be set from the outside.

Like the input unit 17, the input unit 17a may be a communication circuit that communicates with an external device, an interface circuit of an external medium that reads data from an external medium, a keyboard, a mouse, or the like. It may be an input means. Further, when the input unit 17a receives an input from an operator, display means such as a display and a monitor are also used as the input unit 17a. The parameter and command pattern information to be identified may be input to the input unit 17a from an external device in the form of a numerical control program, or may be input to the input unit 17a interactively by an operator. Further, the input unit 17a may create a program in the form of interactive programming, and the parameter to be identified and the command pattern information may be specified by this program. The input unit 17a outputs the received parameters to be identified to the identification unit 13a, and outputs the received command pattern information to the identification operation generation unit 14b. The operations of the identification unit 13a and the correction unit 11 are the same as those in the third embodiment.

The identification motion generation unit 14b generates a command pattern for the identification motion based on the command pattern information of the identification motion received by the input unit 17a, and outputs the identification motion command to the drive control unit 15. Further, the identification motion generation unit 14b modifies the identification motion command pattern based on the identification motion correction signal output from the identification unit 13a, similarly to the identification motion generation unit 14a of the second embodiment. The operation of the numerical control device 1c of the present embodiment other than the above is the same as that of the numerical control device 1b of the third embodiment.

As described above, in the numerical control device 1c of the fourth embodiment, in addition to the parameters of the identification target described in the third embodiment, the command pattern of the identification operation can be set by input from the outside. Therefore, the numerical control device 1c of the fourth embodiment has an effect that the identification result can be preferentially calculated for the combination of the parameters specified by the input from the outside.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1,1a, 1b, 1c Numerical control device, 2 Machine tool, 11 Correction unit, 12 Vibration determination unit, 13 Identification unit, 14 Identification motion generation unit, 15 Drive control unit, 16 Data acquisition unit, 17, 17a Input unit.

Claims (8)

A numerical control device that controls the operation of a machine tool that has a spindle and a feed shaft and processes workpieces with tools.
An identification motion generator that generates an identification motion command that independently and continuously changes the rotation speed of the spindle and the feed rate, respectively.
The control signal for controlling the machine tool generated based on the identification operation command and the operation state signal representing the operation state of the machine tool operated based on the control signal are synchronized and used as identification data. Data acquisition unit to output and
Based on the identification data, a vibration determination unit that determines whether the vibration state of the machine tool is stable machining, chatter vibration, or forced vibration.
Based on the discrimination result of the vibration determination unit, the identifiable machining characteristic parameter is selected as the selection parameter from the machining characteristic parameters representing the characteristics of the machining phenomenon between the tool and the work, and the identification data is used. The identification unit that identifies the selection parameters and
A numerical control device characterized by being provided with. The identification unit is characterized in that, based on the discrimination result of the vibration determination unit, an identifiable dynamic characteristic parameter is selected as the selection parameter from the dynamic characteristic parameters representing the vibration characteristics of the machine tool. The numerical control device according to claim 1. The identification unit is a parameter for which identification has not been completed, which is a parameter set as an identification target after the identification is performed using the identification data for a period corresponding to the identification operation command. Is present, a command change signal instructing the change of the identification operation is generated and output to the identification operation generation unit.
Upon receiving the command change signal, the identification action generation unit changes the identification action command and changes the identification action command.
The data acquisition unit synchronizes the control signal generated based on the changed identification operation command with the operation state signal representing the operation state of the machine tool operated based on the control signal to perform the identification. The numerical control device according to claim 1 or 2, wherein the data is output to the vibration determination unit and the identification unit. An input unit that accepts the input of the identification target parameter from the outside,
The numerical control device according to claim 3, further comprising. The input unit inputs command pattern information from the outside, which is information indicating a waveform with respect to the rotation speed and the time of the feed speed when the rotation speed and the feed speed are changed by the identification operation command. Acceptance,
The numerical control device according to claim 4, wherein the identification operation generation unit generates the identification operation command based on the command pattern information. The numerical control device according to claim 4 or 5, wherein the input unit receives an input from the outside as a numerical control program. The numerical control device according to claim 4 or 5, wherein the input unit receives an input from the outside in the form of interactive programming. A correction unit that generates a correction signal to correct the operation of the machine tool based on the identification result.
The numerical control device according to any one of claims 1 to 7, wherein the numerical control device is provided.

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