Numerical Control Device

Abstract

The numerical control device (1) includes a rotation command output unit (13) that outputs a rotation command to rotate the workpiece and the tool relatively, and a feed command output unit (12) that outputs a feed command to move the workpiece and the tool relatively, and the feed command can include a vibration motion command that alternately repeats forward motion and backward motion. One vibration in the vibration motion command includes a first section in which the tool moves at a first speed that is the moving speed during forward motion, a second section in which the tool moves at a second speed that is the moving speed during backward motion, and a third section in which the tool moves at a third speed that is the moving speed during forward motion and is slower than the first speed.

Description

[Technical field]

[0001] The present disclosure relates to a numerical control device that is a control device for a machine tool. [Background technology]

[0002] In cutting processing, a vibration cutting function is known in which a cutting tool and a workpiece are relatively vibrated in the processing direction to break up chips into small pieces (for example, Patent Document 1).

[0003] During machining using the vibration cutting function, cutting is performed by alternating between forward motion in the same direction as the machining direction and backward motion in the opposite direction to the machining direction. The relative movement speed between the cutting tool and the workpiece during forward motion is higher than the relative movement speed during non-vibration machining, which is normal machining that does not involve vibration cutting, so even when a backward motion is performed, it is possible to make the average relative movement speed, which is the sum of forward and backward motions, equivalent to the relative movement speed during non-vibration machining, which allows vibration cutting to be applied without changing the machining time, i.e., productivity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7096227 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, when the vibration cutting function is used, the relative movement speed during forward movement becomes faster than in non-vibration machining, and the load between the tool and the workpiece temporarily increases. At this time, problems such as accelerated tool wear or tool damage may occur due to excessive cutting force or cutting heat, or machining conditions such as the feed rate indicating the relative movement speed between the tool and the workpiece, the spindle rotation speed indicating the relative rotation speed between the tool and the workpiece, and the cutting thickness may not be satisfied, resulting in a deterioration in the machined surface quality indicating the smoothness of the machined surface.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a numerical control device that can reduce machining problems caused by the increased relative moving speed between the tool and the workpiece in vibration cutting. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the numerical control device disclosed herein comprises a rotation command output unit which outputs a rotation command for rotating the workpiece and the tool relatively, and a feed command output unit which outputs a feed command for moving the workpiece and the tool relatively, and the feed command can include a vibration motion command for alternately repeating forward and backward motions. One vibration in the vibration motion command includes a first section in which the machine moves at a first speed which is the moving speed during forward motion, a second section in which the machine moves at a second speed which is the moving speed during backward motion, and a third section in which the machine moves at a third speed which is the moving speed during forward motion and is slower than the first speed. The numerical control device has respective section ratio determination units which determine the ratio of the first section, the second section, and the third section in one vibration in the vibration motion command, and the section ratio determination units determine a ratio of the first section, the second section, and the third section in one vibration in the vibration motion command based on a machining program. According to the combination of strings and numbers that specify the ratio of each interval, The ratios of the first interval, the second interval, and the third interval are determined. Effect of the Invention

[0008] According to the numerical control device of the present disclosure, it is possible to reduce machining problems caused by an increase in the relative moving speed between the tool and the workpiece in vibration cutting. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a configuration example of a numerical control device according to a first embodiment. [Diagram 2] FIG. 1 is an explanatory diagram showing a method for determining an end point of a retreating motion of the numerical control device according to the first embodiment; [Diagram 3] FIG. 1 is an explanatory diagram of a method for determining a waveform of a forward motion of the numerical control device according to the first embodiment; [Figure 4] Diagram explaining how to determine the basic vibration waveform [Diagram 5] FIG. 1 is an explanatory diagram of a method for determining a vibration waveform having a third section in the numerical control device according to the first embodiment; [Figure 6] FIG. 11 is an explanatory diagram of a method for determining another basic vibration waveform that does not have a third section in the numerical control device according to the first embodiment. [Figure 7] FIG. 13 is an explanatory diagram of a method for determining another vibration waveform having a third section in the numerical control device according to the first embodiment. [Figure 8] FIG. 13 is an explanatory diagram of a method for determining another vibration waveform having a third section in the numerical control device according to the first embodiment. [Figure 9] FIG. 11 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. [Figure 10] FIG. 11 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. [Figure 11] FIG. 11 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. [Figure 12] FIG. 11 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. [Figure 13] FIG. 11 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. [Figure 14] FIG. 13 is a diagram showing an example of a data table used to create a vibration waveform having a third section in the numerical control device of the first embodiment. [Figure 15]FIG. 13 is a diagram showing another example of a data table used to create a vibration waveform having a third section in the numerical control device of the first embodiment. [Figure 16] FIG. 13 is a block diagram showing a configuration during learning of a numerical control device according to a third embodiment. [Figure 17] FIG. 13 is a diagram showing a configuration example of a neural network used in a numerical control device according to a third embodiment. [Figure 18] Flowchart regarding learning processing of a numerical control device according to a third embodiment [Figure 19] FIG. 13 is a block diagram showing a configuration during inference of a numerical control device according to a third embodiment. [Figure 20] Flowchart regarding inference processing of the numerical control device according to the third embodiment [Figure 21] FIG. 1 is a diagram showing an example of a hardware configuration of a numerical control device according to first to third embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A numerical control device according to an embodiment will be described in detail below with reference to the drawings.

[0011] Embodiment 1 1 is a block diagram showing a configuration example of a numerical control device according to embodiment 1. The numerical control device 1 in this embodiment has a machining program analysis unit 10, an interval ratio determination unit 15, a vibration command generation unit 11, a feed command output unit 12, a rotation command output unit 13, and a load information acquisition unit 14.

[0012] The machining program analysis unit 10 analyzes the machining program 16 and outputs information on the operation commands described in the machining program 16 to each section ratio determination unit 15 and the vibration command generation unit 11 .

[0013] The format of the machining program 16 does not matter; for example, it may be a string of characters in EIA (Electronic Industries Alliance) / ISO (International Organization for Standardization) format, or it may be a program called an interactive program that includes information such as the shape of the workpiece, the machining shape, and dimensions.

[0014] The information of the motion command includes the coordinate values ​​of the start point and the end point that define the relative movement path between the tool and the workpiece, the interpolation method (linear interpolation, circular interpolation, etc.) of the movement path connecting the start point and the end point, the feed rate during movement, the number of rotations of the spindle, the direction of rotation, etc. Furthermore, the information of the motion command may include information specifying whether vibration cutting is effective or not, and the shape of the vibration waveform. Examples of information specifying the shape of the vibration waveform include the vibration frequency, the vibration amplitude, the number of vibrations per unit time or the number of vibrations per unit time, and information regarding the ratio of each section, which will be described later. Note that it is not necessary to specify all of the information specifying the shape of the vibration waveform, and some of it may be omitted.

[0015] The section ratio determination unit 15 determines the ratios of the first section, the second section, and the third section in one vibration (hereinafter, may be referred to as each section ratio, each section ratio, etc.). One vibration is a unit of vibration superimposed on a normal machining movement operation in vibration cutting, and for example, when the vibration number N is 1.0, the rotation angle of the main spindle per vibration is 360 degrees. The section ratio determination unit 15 outputs the determined ratios to the vibration command generation unit 11. The method of determining each section ratio may be based on information from the machining program analysis unit 10, or may be based on the value of external information such as a parameter set in advance.

[0016] The vibration command generating unit 11 calculates a vibration waveform based on information from the machining program analyzing unit 10, and creates a feed command for the feed axis and a rotation command for the spindle. The calculation method of the vibration waveform will be described later. The ratio of each section in the vibration operation may use information input from each section ratio determining unit 15, or may refer to information such as a parameter set in advance and determine the ratio based on the value.

[0017] Feed command output unit 12 outputs the feed command generated by vibration command generation unit 11 to a feed unit 2 of a machine tool to be controlled. As the feed unit 2, a servo motor and a servo amplifier that controls the servo motor are assumed, but there are no particular limitations as long as it is a means that can realize relative movement between a workpiece and a tool and realize vibration operation.

[0018] The rotation command output unit 13 outputs the rotation command generated by the vibration command generation unit 11 to a rotating unit 3 of a machine tool to be controlled. The rotating unit 3 is assumed to be a spindle motor and a spindle amplifier that controls the spindle motor, but there are no particular limitations as long as it is a means that can realize relative rotation between a workpiece and a tool.

[0019] Machining by vibration cutting is achieved by the feed unit 2 and the rotation unit 3 moving and rotating the workpiece and the tool relatively in accordance with the feed command and rotation command generated by the vibration command generation unit 11. The workpiece is cut by contacting the relatively rotating workpiece and the tool, and the relative movement realizes machining into the desired shape. This movement is accompanied by vibration, which causes a miss due to the forward and backward movement, i.e., an interruption of the cutting process, and exerts the effect of vibration cutting, which breaks up the chips into small pieces.

[0020] The method for calculating the vibration waveform will be explained below. First, an example will be explained in which the number of vibrations N per one rotation of the spindle is 0.5, that is, one vibration occurs for two rotations of the spindle.

[0021] Hereinafter, the speed of relative movement between the workpiece and the tool will be referred to as the feed speed. The unit of the feed speed may be the amount of movement per unit time, for example, mm / min, or the amount of movement per one rotation of the spindle, for example, mm / rev. In this embodiment, there is no particular restriction on either feed speed, but for ease of understanding, the description will be given using the amount of movement per one rotation of the spindle.

[0022] First, a method for determining the end point of the retreat operation waveform will be described with reference to FIG. 2. FIG. 2 is an explanatory diagram of a method for determining the end point of the retreat operation of the numerical control device of the first embodiment. In FIG. 2, the vertical axis indicates the position of the feed axis, and the horizontal axis indicates the spindle angle. Va indicates the movement speed (movement waveform) of the feed axis during non-vibration machining, which is normal machining without vibration cutting. V1 indicates the movement speed (movement waveform) of the forward movement during vibration machining. V2 indicates the movement speed (movement waveform) of the retreat operation during vibration machining. In this description, the number of vibrations N per one spindle revolution is 0.5, so the waveforms of two spindle revolutions, that is, the waveform of the Mth spindle revolution and the waveform of the M+1th spindle revolution, are shown. In FIG. 2, it is assumed that the initial angle of the spindle at the Mth revolution is 0 degrees.

[0023] If the feed shaft returns to the same position as when it moved at the feed shaft speed Va during non-vibration machining when one vibration operation is completed, the average feed speed will not change whether vibration cutting is enabled or disabled, and machining can be performed without changing the machining time. Therefore, the end point E2 of the movement waveform V2 of the backward operation is taken on the straight line indicating the feed shaft speed Va during non-vibration machining. In addition, since the number of vibrations N per spindle rotation is 0.5, the end point E2 of the movement waveform V2 of the backward operation is the position at which the spindle rotates 720 degrees from the start point S1 of the movement waveform V1 of the forward operation. In this way, the end point E2 of the movement waveform V2 of the backward operation is determined.

[0024] Next, a method for determining the moving waveform V1 of the forward movement will be described with reference to FIG. 3. FIG. 3 is an explanatory diagram of a method for determining the waveform of the forward movement of the numerical control device of the first embodiment. In FIG. 3, the vertical axis indicates the position of the feed axis, and the horizontal axis indicates the spindle angle. Va indicates the moving speed of the feed axis during non-vibration machining. V1 indicates the moving speed of the forward movement during vibration machining. V2 indicates the moving speed of the retreating movement during vibration machining. As shown by the arrow K1 in FIG. 3, by moving the moving waveform V1 of the forward movement at the Mth rotation of the spindle to the M+1th rotation of the spindle, consider how the part machined with the moving waveform V1 of the forward movement at the Mth rotation of the spindle is related to the moving waveform V2 of the retreating movement at the M+1th rotation of the spindle. If the moving waveform V2 of the retreating movement and the moving waveform V1 of the forward movement at the Mth rotation of the spindle shown by the dashed line intersect, theoretically, an idling movement occurs in the area including this intersection, and the chip is broken.

[0025] However, in reality, the amplitude at the tool cutting edge may be attenuated below the command amplitude, and the chips may not be broken. This is thought to be due to the influence of the drive feed mechanism such as the ball screw and the mechanical structure of the tool post, etc., that exist between the motor and the tool cutting edge. Therefore, in reality, it is desirable to adjust the vibration waveform so that the end point E1 of the forward movement is greater than the end point E2 of the backward movement and a certain amount of margin α is left so that an idling section occurs.

[0026] By such a method, the slope of the moving waveform V1 of the forward motion of the Mth rotation of the spindle, that is, the first speed which is the moving speed V1 of the forward motion, is determined. FIG. 4 is an explanatory diagram of a method for determining a basic vibration waveform. As shown in FIG. 4, if the ratio between the first section which is the section of the forward motion and the second section which is the section of the backward motion is, for example, 0.5:0.5, the end point E1 of the forward motion is determined. With this end point E1 as the starting point, the slope of the moving waveform V2 of the backward motion is also determined, and the second speed which is the moving speed V2 of the backward motion is determined. As a result, a basic vibration waveform including the forward motion of the first section and the backward motion of the second section but not including the third section is calculated, and the vibration amplitude W is also determined. The vibration amplitude W is expressed, for example, as the distance between the end point E1 of the forward motion and the position during non-vibration machining corresponding to this end point E1.

[0027] The above is the basic method of calculating the vibration waveform. However, the calculation method of the vibration waveform is not limited to this, and for example, a method of calculating the vibration waveform from the vibration frequency, determining the presence and size of the miss-swing area, and adjusting the amplitude is also possible. In Figure 4, the area shown by hatching is the miss-swing area G.

[0028] Here, in the first embodiment, for example, a third section in which the actuator moves forward at a third speed V3 slower than the first speed is provided between a first section in which the actuator moves forward at a first speed V1 and a second section in which the actuator moves backward at a second speed V2. A method for calculating a vibration waveform having a third section in which the actuator moves at the third speed V3 will be described below. As an example, a case will be described in which the ratio of the first section is not changed, the second section is halved, half of the second section is used as the second section, and the remaining half of the second section is used as the third section.

[0029] The calculation up to obtaining the end point E1 of the forward motion is the same as that explained in FIG. 2 and FIG. 3. FIG. 5 is an explanatory diagram of a method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. In FIG. 5, the third speed V3 is set to be the same as the moving speed Va of the feed axis during non-vibration machining. When the third speed V3 is determined, the end point E3 of the waveform at the third speed V3 is calculated according to the ratio of the third section, and the second speed V2 is determined by calculating the waveform of the retreat motion with the end point E3 as the start point and the end point E2 of the retreat motion as the end point. In this manner, a vibration waveform having the section of the third speed V3 can be calculated without changing the vibration amplitude W.

[0030] In the example of Figure 5, the third speed V3 is the same as the movement speed Va of the feed axis during non-vibration machining, but the third speed V3 may be any other speed as long as it is lower than the first speed V1.

[0031] Here, we will supplement the relationship between the top and bottom dead points of the vibration waveform and the waveform of the feed axis position during non-vibration machining. The waveform of the feed axis position during non-vibration machining is the feed axis position required to obtain the shape you want to achieve through machining. In other words, if the cutter advances toward the workpiece further than the waveform of the feed axis position during non-vibration machining, the desired shape will be cut into, and in the opposite case, some part will be left uncut. If some part is left uncut, it is possible to achieve the desired shape through additional machining, but once the part is cut into, it cannot be restored using normal cutting, so cutting into the workpiece must be avoided.

[0032] In this embodiment, by matching the top dead center or bottom dead center of vibration with the waveform of the feed axis position during non-vibration machining, vibration cutting is performed while avoiding gouging.

[0033] FIG. 6 is an explanatory diagram of a method for determining another basic vibration waveform having no third section in the numerical control device of the first embodiment. In FIG. 6, the ratio of the first section is three times the ratio of the second section. FIG. 7 is an explanatory diagram of a method for determining another vibration waveform having a third section in the numerical control device of the first embodiment. In FIG. 7, a third section is added to the vibration waveform of FIG. 6, so that the first section:second section:third section=0.5:0.25:0.25. In order to easily understand the difference between FIG. 6 and FIG. 7, in the vibration waveform of FIG. 6, the movement waveform of the previous forward movement and the movement waveform of the current backward movement intersect at positions of 720 degrees and 1440 degrees.

[0034] As shown in Figures 6 and 7, when the ratio of the first section is reduced from 0.75 to 0.5 and a third section is added, the start point S2 of the second section is set as the end point E3 of the third section, and the start point S3 of the third section is calculated in the opposite manner to the above example. The first speed is determined by setting the start point S3 of the third section as the end point E1 of the first section. In Figure 7, the third speed V3 is set to the same as the moving speed Va of the feed axis during non-vibration machining.

[0035] Fig. 8 is an explanatory diagram of a method for determining another vibration waveform having a third section in the numerical control device of the embodiment 1. In Fig. 8, the third speed V3 is set to a speed slower than the first speed V1 and different from the moving speed Va of the feed axis during non-vibration machining. In the case of Fig. 8, the end position of the first section changes.

[0036] So far, a case has been described in which the number of vibrations N per one spindle revolution is 0.5, but this embodiment is applicable regardless of the value of the number of vibrations N. Also, a calculation method has been shown in which a third section is added after the first and second sections have been determined, but it is also possible to calculate the vibration waveform from the vibration amplitude W and the ratio of each section.

[0037] Next, a procedure for calculating a vibration waveform based on the vibration amplitude W and the ratio of each section will be described using an example where the vibration frequency N is 1.5. For example, consider a case where a ratio of first section:third section:second section = 0.5:0.25:0.25 is given, and the moving speed Va of the feed axis during non-vibration machining and the vibration amplitude W are given. FIG. 9 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. FIG. 10 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. As shown in FIG. 9, it is assumed that the ratio of each section, first section:third section:second section = 0.5:0.25:0.25, the moving speed Va of the feed axis during non-vibration machining, and the vibration amplitude W are given.

[0038] Since the number of vibrations N is 1.5, the rotation angle of the spindle per vibration is 240 degrees. The length of each section (spindle angle) is determined by dividing this rotation angle of the spindle per vibration by the ratio of each section.

[0039] For example, if the third speed V3 is set to the same speed as the feed axis moving speed Va during non-vibration machining, the start point S3 and end point E3 of the third section are determined as shown in Figure 10, and the first speed V1 is determined by dividing the distance to the start point S3 of the third section by the length of the first section (spindle angle). The second speed can be calculated in a similar manner. Note that the end point E2 of the second section is a position where the spindle angle has advanced 240 degrees at the normal feed speed without vibration.

[0040] Fig. 11 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the embodiment 1. In Fig. 11, the third speed V3 is set to a speed slower than the first speed V1 and different from the moving speed Va of the feed axis during non-vibration machining. When the third speed V3 is set to an arbitrary speed lower than the first speed V1, the waveform can be calculated by setting the first speed V1 to a speed in a range higher than the speed calculated when the first speed V1 = the third speed V3.

[0041] In the explanations so far, we have shown examples in which the third section is provided only at the point where the first speed V1 switches to the second speed V2, and examples in which the third section is provided only at one point during one vibration, but this is not limited to these and various other patterns can be used.

[0042] For example, it is possible to provide a third section at the switching point from the second speed V2 to the first speed V1. Fig. 12 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. In Fig. 12, a third section operating at a third speed V3 is provided at both the switching point from the first speed V1 to the second speed V2 and the switching point from the second speed V2 to the first speed V1.

[0043] Furthermore, a third section may be inserted in the middle of the first section and in the middle of the second section to divide the first section and the second section. Fig. 13 is an explanatory diagram of another method for determining a vibration waveform having a third section in the numerical control device of the first embodiment. In Fig. 13, a third section operating at a third speed V3 is provided in the middle of the first section, in the middle of the second section, at the point of switching from the first speed V1 to the second speed V2, and at the point of switching from the second speed V2 to the first speed V1.

[0044] For the calculation to obtain such a vibration waveform, a data table in which a set of the ratio of each section and the speed of each section is stored in order as shown in FIG. 14 and FIG. 15 may be used. FIG. 14 is a diagram showing an example of a data table used for creating a vibration waveform having a third section in the numerical control device of the first embodiment. FIG. 15 is a diagram showing another example of a data table used for creating a vibration waveform having a third section in the numerical control device of the first embodiment. In the data table of FIG. 14, a third section operating at a third speed V3 is provided at a switching point from the first section operating at the first speed V1 to the second section operating at the second speed V2 and at a switching point from the second section to the first section. In the data table of FIG. 15, a third section operating at a third speed V3 is provided in the middle of the first section, in the middle of the second section, at a switching point from the first speed V1 to the second speed V2, and at a switching point from the second speed V2 to the first speed V1.

[0045] As described above, according to the numerical control device of the first embodiment, since the third section is provided in which machining is performed at the third speed V3, which is slower than the first speed V1, machining problems caused by high feed rates can be reduced. For example, by reducing the cutting force and cutting heat generated during machining, it is expected that the tool life will be extended and the quality of the machined surface will be improved.

[0046] In addition, according to the numerical control device of the first embodiment, the cutting force is reduced in the area machined at the third speed V3 compared to the area machined at the first speed V1, so that the amount of elastic deformation occurring in the workpiece can be reduced, and the effect of easily breaking up the chips is achieved. That is, when the cutting force during forward movement increases, the amount of elastic deformation increases if the rigidity of the workpiece itself or the tool support structure including the machine, tool, tool rest, etc. is low. The effect of breaking up the chips in vibration cutting is achieved by the reciprocating movement passing again the part machined one spindle revolution ago, causing the workpiece and the tool to strike an idle, and the machining becomes intermittent. When the amount of elastic deformation increases, the workpiece and the tool move relatively farther away from each other, and the amount of cut decreases. Then, a problem occurs in which the part that was originally machined one spindle revolution ago is not machined, and even under conditions that should theoretically result in an idle operation, the workpiece and the tool do not strike an idle, and the effect of breaking up the chips is not obtained. However, according to the numerical control device of the first embodiment, this problem can be solved.

[0047] Furthermore, according to the numerical control device of the first embodiment, by providing a third section in which machining is performed at a third speed V3 in the switching section between the first speed V1 and the second speed V2, it is possible to suppress abrupt speed changes and reduce acceleration during reversal. This makes it possible to reduce various problems caused by vibrations due to acceleration. That is, if the third section is not provided, forward and backward movements are switched instantly, so that a large acceleration occurs during reversal movement in the feed axis performing the vibration cutting operation. The acceleration generated in the feed axis not only deteriorates the machined surface quality by exciting relative vibrations between the workpiece and the tool, but also becomes a vibration source that vibrates the entire machine, causing problems such as machine resonance and vibration of the machine structure. According to the numerical control device of the first embodiment, for example, it is possible to prevent deterioration of the machined surface quality due to vibrations of the tool, and prevent wear of fastening parts due to machine vibration.

[0048] In addition, the speed may be changed smoothly at the switching portion of each speed section. For example, the speed change can be made smooth by providing a smoothing filter such as a moving average filter immediately before outputting a feed command containing vibration in the vibration command generating unit 11. This is expected to further reduce the acceleration caused by the change between each speed, and to further suppress vibration.

[0049] As a modified example, a waveform equivalent to the waveforms described above may be generated by superposing multiple sine waves that differ from each other in one or more of phase, frequency, and amplitude. By using a sine wave as the basis, a smoother moving waveform can be obtained.

[0050] Embodiment 2 In the second embodiment, a more detailed description will be given of a method for determining the ratio of each section performed by each section ratio determination unit 15. The configuration of the numerical control device 1 in the second embodiment is the same as that of the numerical control device 1 shown in Fig. 1, and therefore a duplicated description will be omitted.

[0051] The method for determining the ratio of each section is as follows: (1) A method using input by a machining program 16; (2) A method using load information of the feeding unit 2 or the rotating unit 3; (3) Method using predefined parameters Note that other methods may be used, or a combination of methods (1) to (3) may be used.

[0052] (1) A method using input from the machining program 16 will be described. The section ratio determination unit 15 determines each section ratio based on the character string and numerical value described in the machining program 16. For example, in the case of an EIA / ISO program, a configuration may be used in which the first section: second section: third section = 0.5:0.25:0.25 is specified by a combination of character strings and numerical values ​​such as "L0.5 M0.25 N0.25".

[0053] (2) A method of using the load information of the feed unit 2 or the rotation unit 3 will be described. In this embodiment of the method, the numerical control device 1 has a load information acquisition unit 14 as shown in FIG. 1. The load information acquisition unit 14 acquires load information representing the load from the feed unit 2 and the rotation unit 3 at any time. For example, when a servo motor and a servo amplifier are used as the feed unit 2, the servo motor generates torque to achieve a desired operation while resisting the load generated by machining. If the load increases, the opposing torque also increases, so a large current flows in proportion to the torque. Therefore, an example of the load information acquired by the load information acquisition unit 14 is feedback information of this current. Other load information may be a feedback value of the torque, or an actual load value acquired by an acceleration sensor or a pressure gauge such as a load cell attached to the servo motor.

[0054] Furthermore, when a spindle motor and a spindle amplifier are used as the rotating unit 3, a torque is generated to maintain the relative rotational speed between the tool and the workpiece. When the tool and the workpiece come into contact with each other during machining, a load acts in the direction that reduces the rotational speed, and a torque is generated to counter this. Therefore, using the same theory as the servo motor described above, load information can be obtained by acquiring the current feedback value and torque feedback value.

[0055] Next, a method for determining each section ratio based on the load information will be described. When the set values ​​of each section ratio and the like included in the information specifying the shape of the vibration waveform are appropriate in light of the machining conditions and the rigidity of the tool, workpiece, and machine structure, an idling motion occurs in which the workpiece and the tool are separated, and chip separation occurs. During the idling motion, the workpiece and the tool are separated, and the load on the workpiece and the tool is reduced. Therefore, during the idling motion, the load generated on the feed unit 2 and the rotating unit 3 is also reduced. Conversely, when elastic deformation occurs due to a large machining load and no idling motion occurs, machining continues all the time, and therefore no reduction in load occurs. From this, it is possible to determine whether chip separation is occurring normally by monitoring the load information.

[0056] The section ratio determination unit 15, which has acquired the load information from the load information acquisition unit 14, determines whether or not chip breakage has occurred based on the load information, and if it determines that chip breakage will not occur, increases the ratio of the movement section at the third speed. This reduces the machining load and increases the possibility of chip breakage occurring. The extent to which the ratio of the third section is increased may be determined in advance by a parameter or the like, or may be determined to be proportional to the magnitude of the load information. If the load does not decrease even after changing the ratio of the third section, the ratio of the third section may be further increased, and this may be repeated until the load decreases.

[0057] Alternatively, in order to reduce elastic deformation, the ratio of each section itself may be left unchanged, but the first section may be divided and a third section may be added between the divided first sections. Since the effect of relatively reducing elastic deformation can be expected in the section where machining is performed at a third speed lower than the first speed, by dividing the first section and providing a third section between them, rather than providing the first section all at once, the effect of suppressing the amount of elastic deformation and causing chip breakage can be expected even with the same ratio.

[0058] As another example of a method for determining the section ratio, a case where the load exceeds a certain threshold will be described. For example, if the first speed is too high, the load may be too high, which may damage the tool or reduce the quality of the machined surface of the machined workpiece. Therefore, when the load exceeds a certain threshold, the section ratios may be adjusted to lower the first speed. For example, a method of increasing the ratio of the first section may be considered.

[0059] (3) A method using predetermined parameters will be described. Each section ratio determination unit 15 determines each section ratio according to predetermined parameters. A plurality of ratio setting values ​​may be set, and the ratio to be used may be switched according to various threshold values. Examples of threshold values ​​include feed speed, spindle speed, vibration frequency, number of vibrations, and vibration amplitude. Also, combinations of various conditions and threshold values ​​may be prepared in the form of a table or matrix, and a selection may be made.

[0060] The ratio of each section is determined by each of the above methods, and the vibration command generating unit 11 generates a vibration waveform based on the ratio. The method of generating the vibration waveform and the subsequent operations are the same as those in the first embodiment, so the description thereof will be omitted here.

[0061] Thus, according to the second embodiment, it is possible to adjust the ratio of each section depending on the situation. This allows vibration cutting to be performed with a vibration waveform that corresponds to the machining situation, and it is possible to appropriately adjust the load during machining and the acceleration that occurs. In addition, by changing the ratio of each section based on the load information generated on the tool or workpiece, it is possible to automatically adjust each speed and each section ratio appropriately at all times, and it is possible to reliably break up the chips.

[0062] Embodiment 3 In the third embodiment, an example using machine learning will be described. Here, matters specific to the third embodiment will be mainly described, and the following items similar to those in the first and second embodiments will not be described. Fig. 16 is a block diagram showing a configuration during learning of the numerical control device according to the third embodiment.

[0063] In FIG. 16, the state acquisition unit 20 acquires state variables as input values ​​for machine learning during machining by vibration cutting. The state variables may include data representing machining conditions, data representing vibration conditions, data representing feed operation content, and data representing the ratios of the first section, the second section, and the third section in one vibration, i.e., data representing each section ratio. The data representing machining conditions includes, for example, the above-mentioned operation command information, and is acquired from the machining program analysis unit 10. The data representing vibration conditions includes, for example, information specifying the shape of the above-mentioned vibration waveform, and is acquired from the vibration command generation unit 11. The data representing feed operation content includes, for example, the above-mentioned feed command, and is acquired from the vibration command generation unit 11. The data representing each section ratio is acquired from the vibration command generation unit 11.

[0064] The judgment unit 22 judges whether the machining by vibration cutting is good or bad based on the load information acquired from the load information acquisition unit 14. The judgment result is output to the learning unit 21 as machining good or bad judgment data. The method of judging the good or bad may be to judge whether or not a miss has occurred simply from the load information, or to use the load exceeding a certain threshold as a criterion. The judgment may also be made using statistics of the load for a certain period of time. For example, when the load fluctuates greatly, speed changes occur frequently and there is a concern of a decrease in the quality of the machined surface, so the judgment may be negative.

[0065] The learning unit 21 learns a rule for determining the ratio of each section in accordance with a training data set created based on a combination of the state variables output from the state acquisition unit 20 and the machining quality judgment data output from the judgment unit 22. In other words, the learning unit 21 generates a trained model that infers the optimal ratio of each section from the state variables and the machining quality judgment data.

[0066] The relationship between the judgment of machining quality and the state variables will be explained. As described above, the state variables include data representing machining conditions, data representing vibration conditions, data representing feed operation content, and data representing each section ratio. For example, when the feed rate, which is an example of data representing machining conditions, is high, the load associated with machining tends to be high even during non-vibration machining, so it is considered that the load during vibration cutting will be even higher. As a result, it can be said that the tendency for the judgment of machining quality to be negative is higher than when the feed rate is low.

[0067] Alternatively, when the vibration amplitude, which is an example of data representing vibration conditions, is large, the idling area tends to become larger, which increases the tendency for chip breakage to occur and for the machining quality to be judged as good.

[0068] In addition, in a feed command, which is an example of data representing the feed operation, it is also possible that differences in characteristics due to the axis including the vibration command affect the judgment of the machining quality. For example, when an axis that operates in the direction of gravity vibrates, the amplitude tends to attenuate in the direction against gravity, so chip breakage tends to be less likely to occur. Or, from the viewpoint of machine structure, when an axis on which a heavy structure is mounted vibrates, the amplitude also tends to attenuate, so chip breakage tends to be less likely to occur, and in either case, the machining quality judgment tends to be negative.

[0069] The learning unit 21 learns a rule for determining an optimal ratio for each section from the tendency of combinations of each state variable and processing quality determination data.

[0070] The learning algorithm used by the learning unit 21 may be a known algorithm such as supervised learning, unsupervised learning, reinforcement learning, etc. Here, as an example, a case where a neural network is applied will be described.

[0071] The learning unit 21 learns the optimal combination of each section ratio by so-called supervised learning, for example, according to a neural network model. Here, supervised learning refers to a method of providing pairs of input and result (label) data to the numerical control device 1, learning the features of the learning data, and inferring the result from the input.

[0072] A neural network is composed of an input layer made up of multiple neurons, an intermediate layer (hidden layer) made up of multiple neurons, and an output layer made up of multiple neurons. The intermediate layer may be one layer, or two or more layers.

[0073] Fig. 17 is a diagram showing an example of the configuration of a neural network used in the numerical control device of the third embodiment. For example, in the case of a three-layered neural network as shown in Fig. 17, when multiple inputs are input to the input layer (X1-X3), the values ​​are multiplied by a weight W1 (w11-w16) and input to the intermediate layer (Y1-Y2), and the result is further multiplied by a weight W2 (w21-w26) and output from the output layer (Z1-Z3). This output result changes depending on the values ​​of the weights W1 and W2.

[0074] In the third embodiment, the neural network learns the optimal ratios of each section by so-called supervised learning according to learning data created based on a combination of state variables acquired by the state acquisition unit 20 and machining quality judgment data output from the judgment unit 22. That is, the neural network learns by inputting state variables to the input layer and adjusting the weights W1 and W2 so that the result output from the output layer approaches the machining quality judgment data. The learning unit 21 generates and outputs a learned model by executing the above-mentioned learning.

[0075] The trained model storage unit 23 stores the trained model output from the training unit 21.

[0076] Next, the learning process of the numerical control device 1 will be described with reference to FIG. 18. FIG. 18 is a flowchart relating to the learning process of the numerical control device 1 of the third embodiment. In step b1, the state acquisition unit 20 acquires state variables, and the judgment unit 22 acquires load information to judge whether machining is good or bad, and outputs machining good or bad judgment data. Note that the state variables and machining good or bad judgment data are acquired and output simultaneously, but it is sufficient that the state variables and machining good or bad judgment data are input in association with each other, and the state variables and machining good or bad judgment data may be acquired and output at different timings. In step b2, the learning unit 21 learns the optimal ratio of each section by so-called supervised learning according to learning data created based on a combination of the state variables acquired by the state acquisition unit 20 and the machining good or bad judgment data output from the judgment unit 22, and generates a learned model. In step b3, the learned model storage unit 23 stores the learned model generated by the learning unit 21.

[0077] 19 is a block diagram showing a configuration of the numerical control device according to the third embodiment at the time of inference. The inference unit 24 infers an optimal interval ratio obtained by using a trained model stored in the trained model storage unit 23. That is, by inputting the state variables acquired by the state acquisition unit 20 to this trained model, it is possible to output the optimal interval ratio inferred from the state variables. Note that the inference unit 24 has been described as outputting the optimal interval ratio using the trained model trained by the state acquisition unit 20 of the numerical control device 1, but it is also possible to acquire a trained model from outside, such as another numerical control device, and output the optimal interval ratio based on this trained model.

[0078] Next, a process for obtaining an optimal ratio for each section using the trained model will be described with reference to FIG. 20. FIG. 20 is a flowchart relating to the inference process of the numerical control device 1 of the third embodiment. In step c1, the state acquisition unit 20 obtains a state variable. In step c2, the inference unit 24 inputs the state variable into the trained model stored in the trained model storage unit 23 to obtain an optimal ratio for each section. In step c3, the inference unit 24 outputs the optimal ratio for each section obtained by the trained model to the numerical control device 1. In step c4, the numerical control device 1 calculates a vibration waveform using the output optimal ratio for each section. This makes it possible to optimally adjust the state of machining using vibration cutting.

[0079] In the present embodiment, the case where supervised learning is applied to the learning algorithm used by the learning unit 21 has been described, but the present invention is not limited to this. As for the learning algorithm, reinforcement learning, unsupervised learning, semi-supervised learning, etc. can be applied in addition to supervised learning. Deep learning, which learns to extract the feature amount itself, can also be used, and machine learning may be performed according to other known methods, such as genetic programming, functional logic programming, and support vector machines.

[0080] Thus, according to the third embodiment, it is possible to determine the optimal ratio of each section depending on the machining conditions by vibration cutting. Since learning is performed while actually performing machining, an accurate method for determining the ratio of each section is learned. In addition, since a trained model that has been trained while actually performing machining is used, accurate inference is possible. For example, in turning, in order to obtain a desired shape, cutting is gradually performed in multiple steps. For example, machining is divided into rough machining, semi-finishing machining, finishing machining, etc. Therefore, since similar machining paths are repeatedly performed, it is also possible to optimize the ratio of each section as machining progresses.

[0081] Here, the hardware configuration of the numerical control device 1 will be described. Fig. 21 is a diagram showing an example of the hardware configuration of the numerical control device 1 according to the first to third embodiments. The numerical control device 1 can be realized by a processor 301, a memory 302, and an interface circuit 303 shown in Fig. 21. An example of the processor 301 is a CPU (also called a Central Processing Unit, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). An example of the memory 302 is a RAM (Random Access Memory) or a ROM (Read Only Memory).

[0082] The numerical control device 1 is realized by the processor 301 reading and executing a program for executing the operation of the numerical control device 1, which is stored in the memory 302. It can also be said that this program causes a computer to execute the procedure or method of the numerical control device 1. The memory 302 is also used as a temporary memory when the processor 301 executes various processes. Note that some of the functions of the numerical control device 1 may be realized by dedicated hardware and some by software or firmware.

[0083] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, and parts of the configurations may be omitted or modified without departing from the gist of the present disclosure. [Explanation of symbols]

[0084] 1 Numerical control device, 2 Feed unit, 3 Rotation unit, 10 Machining program analysis unit, 11 Vibration command generation unit, 12 Feed command output unit, 13 Rotation command output unit, 14 Load information acquisition unit, 15 Each section ratio determination unit, 16 Machining program, 20 Status acquisition unit, 21 Learning unit, 22 Judgment unit, 23 Learned model memory unit, 24 Inference unit, E1, E2, E3 End point, G Missing area, N Vibration frequency, S1, S2, S3 Start point, V1 First speed, V2 Second speed, V3 Third speed, Va Feed axis movement speed during non-vibration machining, W Vibration amplitude, α Margin.

Claims

1. a rotation command output unit that outputs a rotation command for relatively rotating the workpiece and the tool; a feed command output unit that outputs a feed command for moving the workpiece and the tool relatively, A numerical control device capable of including in the feed command a vibration operation command for alternately repeating a forward operation and a backward operation, Within one vibration in the vibration operation command, a first section moving at a first speed that is a moving speed during the forward movement; a second section in which the robot moves at a second speed that is a moving speed during the backward movement; a third section in which the forward movement is performed at a third speed that is slower than the first speed, a section ratio determination unit that determines a ratio of the first section, the second section, and the third section in one vibration in the vibration operation command, The section ratio determination unit determines the ratios of the first section, the second section, and the third section based on an input of a machining program. A numerical control device comprising:

2. A rotation command output unit that outputs a rotation command to rotate the workpiece and the tool relatively; a feed command output unit that outputs a feed command for moving the workpiece and the tool relatively, A numerical control device capable of including in the feed command a vibration operation command for alternately repeating a forward operation and a backward operation, Within one vibration in the vibration operation command, a first section moving at a first speed that is a moving speed during the forward movement; a second section in which the robot moves at a second speed that is a moving speed during the backward movement; a third section in which the forward movement is performed at a third speed that is slower than the first speed, a section ratio determination unit that determines a ratio of the first section, the second section, and the third section in one vibration in the vibration operation command, The section ratio determination unit determines the ratio between the first section, the second section, and the third section based on a predetermined parameter. A numerical control device comprising:

3. The section ratio determination unit selects values ​​according to various thresholds from the plurality of parameters, and determines the ratios of the first section, the second section, and the third section based on the selected parameters.

3. The numerical control device according to claim 2 .

4. A rotation command output unit that outputs a rotation command to rotate the workpiece and the tool relatively; a feed command output unit that outputs a feed command for moving the workpiece and the tool relatively, A numerical control device capable of including in the feed command a vibration operation command for alternately repeating a forward operation and a backward operation, Within one vibration in the vibration operation command, a first section moving at a first speed that is a moving speed during the forward movement; a second section in which the robot moves at a second speed that is a moving speed during the backward movement; a third section in which the forward movement is performed at a third speed that is slower than the first speed, a section ratio determination unit that determines a ratio of the first section, the second section, and the third section in one vibration in the vibration operation command, The each section ratio determination unit determines the ratio of the first section, the second section, and the third section in one vibration in the vibration operation command based on load information representing a load generated on the workpiece and the tool during vibration operation. A numerical control device comprising:

5. The third section is provided at least between the first section and the second section.

5. The numerical control device according to claim 1, wherein the numerical control device is a control device for controlling a control operation of the control unit.

6. The third speed is the same as the relative movement speed between the workpiece and the tool during non-vibration machining.

5. The numerical control device according to claim 1, wherein the numerical control device is a control device for controlling a control operation of the control unit.

7. a state acquisition unit that acquires state variables including at least one of data representing machining conditions, data representing vibration conditions, and data representing feed operation details; and an inference unit that determines a ratio of the first section, the second section, and the third section in one vibration in the vibration operation command based on an output from the trained model when the state variable is input to the trained model.

4. The numerical control device according to claim 3 .

8. The trained model is trained using a training data set including a combination of state variables including at least one of data representing the machining conditions, data representing the vibration conditions, and data representing the feed operation content, data representing the ratio of the first section, the second section, and the third section in one vibration in the vibration operation command, and load information representing the load generated on the workpiece and the tool during vibration operation. The numerical control device according to claim 7 .

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