numerical control device

Abstract

A numerical control device (1) has a rotation command output section (13) that outputs a rotation command that causes a workpiece and a tool to rotate relative to each other, and a feed command output section (12) that outputs a feed command that causes the workpiece and the tool to move relative to each other, the feed command being able to include a vibration motion command that alternately repeats an advancing motion and a retreating motion. In one vibration in the vibration motion command, a first section in which movement is performed at a first speed that is a moving speed at the time of the advancing motion, a second section in which movement is performed at a second speed that is a moving speed at the time of the retreating motion, and a third section in which movement is performed at a third speed that is slower than the first speed and is a moving speed at the time of the advancing motion are included.

Description

Technical Field

[0001] This invention relates to a numerical control device as a control device for working machinery. Background Technology

[0002] In machining, a vibratory cutting function is known to break chips into smaller pieces by causing the cutting tool and the workpiece to vibrate relative to each other in the machining direction (e.g., Patent Document 1).

[0003] In machining using vibratory cutting, cutting is performed by alternately and repeatedly moving forward in the same direction as the machining direction and backward in the opposite direction. The relative speed between the cutting tool and the workpiece during the forward movement is higher than the relative speed during normal machining without vibratory cutting. Therefore, even when backward movement is performed, the average relative speed obtained by combining forward and backward movement can be set to be the same as the relative speed during non-vibratory machining. Thus, vibratory cutting can be applied without changing the machining time or productivity.

[0004] Patent Document 1: Japanese Patent No. 7096227 Summary of the Invention

[0005] However, in Patent Document 1, when using the vibration cutting function, the relative movement speed during the forward motion is faster compared to non-vibration machining, and the load between the tool and the workpiece is temporarily increased. At this time, problems sometimes arise, such as accelerated tool wear or tool damage due to excessive cutting force and heat, or the failure to meet the requirements of the feed rate (representing the relative movement speed of the tool and workpiece), the spindle rotation speed (representing the relative rotation speed of the tool and workpiece), and machining conditions related to the removal thickness, resulting in a deterioration in the smoothness of the machined surface.

[0006] The present invention was made in view of the above circumstances, and its object is to provide a CNC device that can reduce machining problems caused by the increase in relative movement speed between the tool and the workpiece in vibratory cutting.

[0007] To solve the above-mentioned problems and achieve the objective, the CNC device of the present invention includes: a rotation command output unit that outputs a rotation command that causes the workpiece and the tool to rotate relative to each other; and

[0008] The feed command output unit outputs a feed command that moves the workpiece and the tool relative to each other. This feed command can include a vibration command that alternately repeats forward and backward movements. Each vibration in the vibration command includes: a first interval of movement at the forward movement speed (a first speed); a second interval of movement at the backward movement speed (a second speed); and a third interval of movement at the forward movement speed but slower than the first speed (a third speed).

[0009] The effects of the invention

[0010] The CNC device according to the present invention has the following effect: it can reduce machining problems caused by the increase in relative movement speed between the tool and the workpiece in vibratory cutting. Attached Figure Description

[0011] Figure 1 This is a block diagram illustrating a structural example of the numerical control device according to Embodiment 1.

[0012] Figure 2 This is an explanatory diagram related to the method for determining the endpoint of the backward movement of the CNC device in Embodiment 1.

[0013] Figure 3 This is an explanatory diagram related to the waveform determination method of the forward movement of the numerical control device in Embodiment 1.

[0014] Figure 4 This is an illustrative diagram related to the method for determining basic vibration waveforms.

[0015] Figure 5 This is an explanatory diagram related to the method for determining the vibration waveform with a third interval in the numerical control device of Embodiment 1.

[0016] Figure 6 This is an explanatory diagram related to the determination method of other basic vibration waveforms that do not have a third interval in the CNC device of Embodiment 1.

[0017] Figure 7 This is an explanatory diagram related to the method for determining other vibration waveforms having a third interval in the CNC device of Embodiment 1.

[0018] Figure 8 This is an explanatory diagram related to the method for determining other vibration waveforms having a third interval in the CNC device of Embodiment 1.

[0019] Figure 9 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1.

[0020] Figure 10This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1.

[0021] Figure 11 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1.

[0022] Figure 12 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1.

[0023] Figure 13 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1.

[0024] Figure 14 This is a diagram showing an example of a data table used in the numerical control device of Embodiment 1 to create a vibration waveform with a third interval.

[0025] Figure 15 This is a diagram showing another example of a data table used in the numerical control device of Embodiment 1 to create a vibration waveform with a third interval.

[0026] Figure 16 This is a block diagram illustrating the learning structure of the numerical control device involved in Embodiment 3.

[0027] Figure 17 This is a diagram illustrating an example of the structure of the neural network used in the numerical control device of Embodiment 3.

[0028] Figure 18 This is a flowchart related to the learning process of the numerical control device in Implementation 3.

[0029] Figure 19 This is a block diagram illustrating the structure of the numerical control device involved in Embodiment 3 during deduction.

[0030] Figure 20 This is a flowchart related to the inference process of the numerical control device in Implementation 3.

[0031] Figure 21 This is a diagram showing an example of the hardware structure of the numerical control device according to Embodiments 1 to 3. Detailed Implementation

[0032] The numerical control device according to the embodiments will now be described in detail based on the accompanying drawings.

[0033] Implementation method 1.

[0034] Figure 1This is a block diagram illustrating a structural example of the CNC device according to Embodiment 1. The CNC device 1 in this embodiment includes a machining program analysis unit 10, a ratio determination unit for each interval 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.

[0035] The machining program analysis unit 10 analyzes the machining program 16 and outputs the information of the motion instructions recorded in the machining program 16 to the interval ratio determination unit 15 and the vibration instruction generation unit 11.

[0036] The form of the machining program 16 is not considered. For example, it can be a string in the form of EIA (Electronic Industries Alliance) / ISO (International Organization for Standardization), or it can be a program in the form of a dialog containing information such as the shape of the workpiece, the machining shape, and the size.

[0037] The information in the motion command includes the coordinates of the start and end points defining the relative movement path of the tool and workpiece, the interpolation method (linear interpolation, circular interpolation, etc.) of the movement path connecting the start and end points, the feed rate during movement, the spindle speed, and the direction of rotation. Furthermore, the motion command information may include whether vibratory cutting is effective and information specifying the shape of the vibration waveform. Information specifying the shape of the vibration waveform includes information related to the vibration frequency, vibration amplitude, the number of vibrations per unit time or the number of vibrations per unit frequency, and the ratios of the intervals described later. Moreover, it is not necessary to specify all of this information regarding the shape of the vibration waveform; some may be omitted.

[0038] The interval ratio determination unit 15 determines the ratio of the first, second, and third intervals in a single vibration (hereinafter, sometimes referred to as interval ratio, ratio of intervals, etc.). A single vibration is a unit of vibration superimposed on the movement motion of normal machining in vibratory cutting. For example, when the vibration number N is 1.0, the rotation angle of the spindle in each vibration is 360 degrees. The interval ratio determination unit 15 outputs the determined ratio to the vibration command generation unit 11. The method for determining the interval ratio can be based on information from the machining program analysis unit 10, or it can be based on the value of external information such as preset parameters.

[0039] The vibration command generation unit 11 calculates the vibration waveform based on information from the machining program analysis unit 10, and creates feed commands for the feed axis and rotation commands for the spindle. The calculation method for the vibration waveform will be described later. The ratio of each interval in the vibration operation can be determined based on the information input from the interval ratio determination unit 15, or by referring to preset parameters and other information.

[0040] The feed command output unit 12 outputs the feed command generated by the vibration command generation unit 11 to the feed unit 2 of the working machine that controls the object. As the feed unit 2, a servo motor and a servo amplifier that controls the servo motor are considered, but there are no particular restrictions as long as it can realize the relative movement of the workpiece and the tool and realize the vibration action.

[0041] The rotation command output unit 13 outputs the rotation command generated by the vibration command generation unit 11 to the rotating part 3 of the working machine that is being controlled. The rotating part 3 can be a spindle motor and a spindle amplifier that controls the spindle motor, but there are no particular restrictions as long as it can achieve the relative rotation of the workpiece and the tool.

[0042] Vibration cutting is achieved by moving and rotating the workpiece and tool relative to each other according to the feed and rotation commands generated by the vibration command generation unit 11. The relative rotating workpiece and tool come into contact, thereby cutting the workpiece and achieving machining towards the desired shape through relative movement. This movement is accompanied by vibration, which causes wobbling due to forward and backward movements, i.e., interruption of cutting, thus achieving the effect of vibration cutting that breaks the chips into fine pieces.

[0043] The calculation method for the vibration waveform is explained. First, we will take the case where the number of vibrations N per revolution of the spindle is 0.5, that is, the spindle vibrates once for every two revolutions.

[0044] Hereinafter, the relative movement speed of the workpiece and the tool will be referred to as the feed rate. The feed rate is sometimes expressed as the amount of movement per unit time, for example, mm / min, and sometimes as the amount of movement per revolution of the spindle, for example, mm / rev. In this embodiment, there is no particular limitation on either feed rate, but for ease of understanding, the amount of movement per revolution of the spindle will be used for explanation.

[0045] First, based on Figure 2 The method for determining the endpoint of the backward motion waveform is explained. Figure 2 This is an explanatory diagram related to the method for determining the endpoint of the backward movement of the CNC device in Embodiment 1. Figure 2In the diagram, the vertical axis shows the position of the feed axis, and the horizontal axis shows the spindle angle. Va shows the feed axis movement speed (waveform) during normal machining without vibration cutting, i.e., non-vibration machining. V1 shows the forward movement speed (waveform) during vibration machining. V2 shows the backward movement speed (waveform) during vibration machining. In this specification, the number of vibrations N per spindle revolution is set to 0.5, therefore the waveforms for 2 spindle revolutions (i.e., the waveform for the Mth spindle revolution) and the waveform for the (M+1)th spindle revolution are shown. Figure 2 In this case, the initial angle of the spindle during the Mth rotation is assumed to be 0 degrees.

[0046] When one vibration action is completed, if the machine returns to the same position as when it moves at the same speed Va as during non-vibration machining, then the average feed rate remains unchanged regardless of whether vibration cutting is effective or not, and machining can be performed without changing the machining time. Therefore, the endpoint E2 of the retraction waveform V2 is obtained on the straight line representing the feed axis speed Va during non-vibration machining. Furthermore, since the number of vibrations N per revolution of the spindle is 0.5, the endpoint E2 of the retraction waveform V2 is located at the moment when the spindle has rotated 720 degrees from the starting point S1 of the forward waveform V1. The endpoint E2 of the retraction waveform V2 is determined in the above manner.

[0047] Next, based on Figure 3 The method for determining the forward motion waveform V1 is explained. Figure 3 This is an explanatory diagram related to the waveform determination method for the forward movement of the CNC device in Embodiment 1. Figure 3 In the diagram, the vertical axis shows the position of the feed axis, and the horizontal axis shows the spindle angle. Va shows the feed axis speed during non-vibration machining. V1 shows the forward speed during vibration machining. V2 shows the backward speed during vibration machining. Figure 3 As shown by arrow K1, consider the relationship between the portion of the forward motion waveform V1 (representing the Mth rotation of the spindle) processed by moving it to the (M+1th rotation of the spindle) and the backward motion waveform V2 in the (M+1th rotation of the spindle). If the backward motion waveform V2 intersects with the forward motion waveform V1 (represented by the dashed line), then theoretically, a free-swinging motion will occur in the region containing this intersection, and the chips are considered to be broken.

[0048] However, in reality, the amplitude at the tool tip is attenuated compared to the commanded amplitude, and the chips may not be broken. This is believed to be due to the influence of mechanical structures such as the ball screw drive feed mechanism and the tool holder from the motor to the tool tip. Therefore, in practice, it is preferable that the end point E1 of the forward motion is greater than the end point E2 of the backward motion, so as to adjust the vibration waveform by creating a free-swinging range with a certain margin α.

[0049] By using the method described above, the slope of the forward motion waveform V1 of the spindle rotation M revolutions is determined, which is the first velocity of the forward motion velocity V1. Figure 4 This is an explanatory diagram related to the method for determining basic vibration waveforms. For example... Figure 4 As shown, if the ratio of the forward motion interval (first interval) to the backward motion interval (second interval) is set to, for example, 0.5:0.5, the endpoint E1 of the forward motion is determined. Using this endpoint E1 as the starting point, the slope of the backward motion waveform V2 is also determined, as is the second velocity V2, which serves as the backward motion speed. Therefore, by calculating the basic vibration waveform including the forward motion of the first interval and the backward motion of the second interval, but excluding the third interval, the vibration amplitude W is also determined. The vibration amplitude W is, for example, expressed as the distance between the endpoint E1 of the forward motion and the position corresponding to that endpoint E1 during non-vibration processing.

[0050] The above are the basic methods for calculating vibration waveforms. However, the methods for calculating vibration waveforms are not limited to these; for example, methods can also be considered that calculate the vibration waveform based on the vibration frequency, determine the presence and size of the free-floating region, and adjust the amplitude accordingly. Figure 4 In the diagram, the area represented by the shaded line is the pendulum region G.

[0051] Here, in Embodiment 1, for example, between the first interval (the interval in which forward movement occurs at a first speed V1) and the second interval (the interval in which backward movement occurs at a second speed V2), a third interval is provided where forward movement occurs at a speed slower than the first speed, namely a third speed V3. The calculation method for the vibration waveform of the third interval, which moves at the third speed V3, will now be explained. As an example, the following explanation will focus on the case where the ratio of the first interval remains unchanged, the second interval is set to half, half of the second interval is set to the second interval, and the remaining half of the second interval is set to the third interval.

[0052] The calculation continues until the endpoint E1 of the forward motion is determined. Figure 2 and Figure 3 The explanation is the same as in the previous text. Figure 5 This is an explanatory diagram related to the method for determining the vibration waveform with a third interval in the CNC device of Embodiment 1. Figure 5In this process, the third speed V3 is set to be the same as the feed axis movement speed Va during non-vibration machining. Once the third speed V3 is determined, the endpoint E3 of the waveform at the third speed V3 is calculated accordingly, based on the ratio of the third interval. Using this endpoint E3 as the starting point and the endpoint E2 of the retraction motion as the ending point, the waveform of the retraction motion is calculated, thereby determining the second speed V2. As described above, without changing the vibration amplitude W, the vibration waveform of the interval with the third speed V3 can be calculated.

[0053] In addition, Figure 5 In the example, the third speed V3 is set to be the same as the feed axis movement speed Va during non-vibration machining, but if the third speed V3 is a speed lower than the first speed V1, it can be set to any other speed.

[0054] Here, we supplement the relationship between the top dead center and bottom dead center of the vibration waveform and the feed axis position during non-vibration machining. The waveform of the feed axis position during non-vibration machining represents the position of the feed axis required to achieve the desired shape through machining. That is, if the cutting tool enters the workpiece side further than the waveform of the feed axis position during non-vibration machining, overcutting occurs relative to the desired shape; conversely, residual cutting occurs. If residual cutting occurs, the desired shape can be achieved through additional machining, but if overcutting has occurred, it cannot be restored to its original shape in normal machining, therefore, overcutting must be avoided.

[0055] In this embodiment, the waveform of the upper or lower dead center of the vibration is made consistent with the position of the feed axis during non-vibration machining, thereby avoiding excessive cutting while performing vibration cutting.

[0056] Figure 6 This is an explanatory diagram related to the method for determining other basic vibration waveforms that do not have a third interval in the CNC device of Embodiment 1. Figure 6 In this case, the ratio of the first interval is set to 3 times the ratio of the second interval. Figure 7 This is an explanatory diagram related to the method for determining other vibration waveforms having a third interval in the CNC device of Embodiment 1. Figure 7 In Figure 6 A third interval is added to the vibration waveform, resulting in a ratio of first interval: second interval: third interval = 0.5:0.25:0.25. Furthermore, for easier understanding... Figure 6 and Figure 7 The difference, in Figure 6 In the vibration waveform, at positions of 720 degrees and 1440 degrees, the movement waveform of the previous forward movement and the movement waveform of the current backward movement can intersect.

[0057] like Figure 6, Figure 7 As shown, when the ratio of the first interval is reduced from 0.75 to 0.5 and a third interval is added, conversely to the previous example, the starting point S2 of the second interval is used as the ending point E3 of the third interval, and the starting point S3 of the third interval is calculated. The first velocity is determined by setting the starting point S3 of the third interval as the ending point E1 of the first interval. Figure 7 In this process, the third speed V3 is set to be the same as the feed axis movement speed Va during non-vibration machining.

[0058] Figure 8 This is an explanatory diagram related to the method for determining other vibration waveforms having a third interval in the CNC device of Embodiment 1. Figure 8 In this context, the third speed V3 is set to be slower than the first speed V1 and different from the feed axis movement speed Va during non-vibration machining. Figure 8 In this case, the endpoint position of the first interval changes.

[0059] Up to this point, the case where the number of vibrations N per revolution of the spindle is 0.5 has been explained, but this embodiment can be applied regardless of the value of the number of vibrations N. Furthermore, a calculation method has been shown where a third interval is added after the first and second intervals have been determined, but the vibration waveform can also be calculated based on the vibration amplitude W and the ratio of each interval.

[0060] Therefore, the following section explains the order in which the vibration waveform is calculated based on the vibration amplitude W and the ratio of each interval, taking the case where the vibration number N is 1.5 as an example. For example, consider the case where the ratio of the first interval: third interval: second interval = 0.5:0.25:0.25 is assigned to the feed axis movement speed Va and vibration amplitude W during non-vibration machining. Figure 9 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1. Figure 10 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1. For example... Figure 9 As shown, the ratio of each interval is given as 0.5:0.25:0.25, the feed axis speed Va during non-vibration machining, and the vibration amplitude W.

[0061] The number of vibrations N is 1.5, so the rotation angle of the principal axis in each vibration is 240 degrees. The rotation angle of the principal axis in each vibration is divided by the ratio of each interval, thereby determining the length of each interval (principal axis angle).

[0062] Here, for example, if the third speed V3 is set to the same speed as the feed axis's movement speed Va during non-vibration machining, then as follows:Figure 10 As shown, the starting point S3 and ending point E3 of the third interval are determined. Therefore, the first velocity V1 is determined by dividing the distance up to the starting point S3 of the third interval by the length of the first interval (the principal axis angle). Similarly, the second velocity can also be calculated. Furthermore, it should be noted that the ending point E2 of the second interval is the position after the principal axis angle has advanced 240 degrees at the normal feed rate without additional vibration.

[0063] Figure 11 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1. Figure 11 In this process, the third speed V3 is set to a speed slower than the first speed V1 and different from the feed axis movement speed Va during non-vibration machining. When the third speed V3 is set to any speed lower than the first speed V1, the first speed V1 is higher than the speed calculated under the assumption that the first speed V1 = the third speed V3. If the third speed V3 is set within a low range, the waveform can be calculated.

[0064] The description up to this point has shown examples of setting the third interval only at the point where the speed changes from the first speed V1 to the second speed V2 and examples of setting the third interval only at one point in a single vibration, but it is not limited to these examples and can be set to various other modes.

[0065] For example, a third interval can also be set at the point where the speed changes from the second speed V2 to the first speed V1. Figure 12 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1. Figure 12 In the middle, at the part where the first speed V1 switches to the second speed V2 and at the part where the second speed V2 switches back to the first speed V1, there are third intervals where the action is performed by the third speed V3.

[0066] Furthermore, a third interval can be inserted in the middle of the first interval or the middle of the second interval to divide the first and second intervals. Figure 13 This is an explanatory diagram related to other methods for determining the vibration waveform with a third interval in the CNC device of Embodiment 1. Figure 13 In the middle of the first interval, the middle of the second interval, the part where the speed changes from the first speed V1 to the second speed V2, and the part where the speed changes from the second speed V2 to the first speed V1, a third interval is provided where the action is performed by the third speed V3.

[0067] In the calculations used to obtain the vibration waveform described above, methods such as... Figure 14 , Figure 15The calculation is performed by storing a data table containing the ratios and speeds of each interval in sequence. Figure 14 This is a diagram showing an example of a data table used in the numerical control device of Embodiment 1 to create a vibration waveform with a third interval. Figure 15 This is a diagram illustrating another example of a data table used in the CNC device of Embodiment 1 to create a vibration waveform with a third interval. Figure 14 In the data table, a third zone is provided at the points where the action transitions from the first zone (operating at the first speed V1) to the second zone (operating at the second speed V2) and from the second zone back to the first zone, where the action transitions at the third speed V3. Figure 15 In the data table, a third interval is set in the middle of the first interval, the middle of the second interval, the part where the speed changes from the first speed V1 to the second speed V2, and the part where the speed changes from the second speed V2 to the first speed V1, so that the action is performed by the third speed V3.

[0068] As described above, the CNC device according to Embodiment 1 is provided with a third interval for machining at a speed slower than the first speed V1, namely the third speed V3. Therefore, machining problems caused by high feed rates can be reduced. For example, the cutting force and cutting heat generated during machining are reduced, thereby expecting to extend tool life and improve the quality of the machined surface.

[0069] Furthermore, according to the CNC device of Embodiment 1, the cutting force is reduced in the area machined at the third speed V3 compared to the area machined at the first speed V1. This reduces the amount of elastic deformation generated in the workpiece, etc., and facilitates chip breaking. That is, if the cutting force increases during the forward motion, the amount of elastic deformation increases if the rigidity of the workpiece itself or the tool support structure including the machine, tool, tool holder, etc., is low. The chip breaking effect in vibratory cutting is achieved by reciprocating through the portion machined before one spindle rotation, causing the workpiece and tool to swing freely, making the machining intermittent. If the amount of elastic deformation increases, the workpiece and tool move relatively apart, resulting in a smaller feed rate. Consequently, it becomes impossible to machine the portion originally machined before one spindle rotation, and even under conditions that theoretically should be swinging freely, the workpiece and tool do not swing freely, resulting in the inability to achieve chip breaking. However, the CNC device of Embodiment 1 solves this problem.

[0070] Furthermore, according to the CNC device of Embodiment 1, a third interval for machining via a third speed V3 is provided between the switching interval of the first speed V1 and the second speed V2. This suppresses abrupt speed changes and reduces acceleration during reversal. Consequently, problems caused by vibration due to acceleration can be reduced. That is, without the third interval, the forward and backward movements switch instantaneously, resulting in a large acceleration in the feed axis that performs vibratory cutting during reversal. The acceleration generated in the feed axis excites relative vibration between the workpiece and the tool, which not only deteriorates the quality of the machined surface but also becomes a source of vibration affecting the entire machine, causing problems such as mechanical resonance and vibration of the mechanical structure. According to the CNC device of Embodiment 1, for example, the following effects can be expected: preventing deterioration of the machined surface quality caused by tool vibration, or preventing wear of fasteners and other components due to mechanical vibration.

[0071] Furthermore, the switching between different speed ranges can be made to allow for smooth speed changes. As a method of implementation, for example, in the vibration command generation unit 11, a smoothing filter such as a moving average filter is provided before the output of the feed command containing vibration, thereby smoothing the speed changes. This further reduces the acceleration caused by changes between speeds, and is expected to further suppress vibration.

[0072] Furthermore, as a variation, a waveform identical to the waveform described so far can be generated by overlapping multiple sine waves with different phases, frequencies, and amplitudes. By using sine waves as a basis, a smoother moving waveform can be created.

[0073] Implementation method 2.

[0074] In Embodiment 2, the method for determining the ratio of each interval through the interval ratio determination unit 15 will be described in more detail. The structure of the CNC device 1 in Embodiment 2 is similar to... Figure 1 The numerical control device 1 shown is the same, so repeated descriptions are omitted.

[0075] As a method for determining the ratio of each interval,

[0076] (1) Using the input method involved in machining program 16,

[0077] (2) A method using load information from feed unit 2 or rotating unit 3.

[0078] (3) The method of using predetermined parameters is used for explanation. Alternatively, other methods may be used, and multiple methods from (1) to (3) may be combined.

[0079] (1) The method of inputting the machining program 16 will be explained. In the interval ratio determination unit 15, the interval ratio is determined based on the string and value recorded in the machining program 16. For example, in the case of the EIA / ISO program, the structure can be specified as first interval: second interval: third interval = 0.5: 0.25: 0.25 by combining the string and value such as "L0.5M0.25 N0.25".

[0080] (2) A method for using load information from the feed unit 2 or the rotary unit 3 will be described. In an embodiment of this method, the CNC device 1, as... Figure 1 As shown, a load information acquisition unit 14 is included. The load information acquisition unit 14 continuously acquires load information representing the load from the feed unit 2 and the rotation unit 3. For example, when a servo motor and servo amplifier are used as the feed unit 2, the servo motor generates torque to counteract the load generated during processing and to achieve the desired action. If the load increases, the torque to be counteracted also increases, and therefore a large current flows proportionally to the torque. Therefore, as an example of the load information acquired by the load information acquisition unit 14, feedback information of this current is given. In addition, the load information may also be a torque feedback value, or the actual load value obtained by a pressure gauge such as an accelerometer or force sensor installed on the servo motor.

[0081] Furthermore, when a spindle motor and spindle amplifier are used as the rotating part 3, torque is generated to maintain the relative rotational speed of the tool and workpiece. During machining, the tool and workpiece come into contact, and a load is applied in the direction that reduces the rotational speed. Torque is generated to counteract this load. Therefore, by using the same principle as the aforementioned servo motor, current feedback values ​​and torque feedback values ​​can be obtained, thereby obtaining load information.

[0082] Next, the method for determining the ratio of each interval based on load information will be explained. When the set values ​​of the interval ratios, etc., included in the information specifying the shape of the vibration waveform are appropriate in comparison with the machining conditions and the rigidity of the tool, workpiece, and mechanical structure, a free-swinging motion occurs, causing the workpiece and tool to separate, resulting in chip breakage. During the free-swinging motion, the workpiece and tool separate, thus reducing the load on the workpiece and tool. Therefore, the load generated in the feed section 2 and the rotating section 3 also decreases during the free-swinging motion. Conversely, due to the large machining load, elastic deformation occurs, and machining continues without a free-swinging motion, thus no load reduction occurs. Therefore, by monitoring the load information, it is possible to determine whether chip breakage occurs normally.

[0083] The interval ratio determination unit 15, which obtains load information from the load information acquisition unit 14, determines whether chip breakage has occurred based on the load information. If it determines that chip breakage has not occurred, it increases the ratio of the movement interval at the third speed. This reduces the machining load and increases the likelihood of chip breakage. The extent to which the ratio of the third interval is increased can be predetermined by parameters or determined in a manner proportional to the magnitude of the load information. If changing the ratio of the third interval does not reduce the load, the ratio of the third interval can be further increased until a load reduction occurs, and this process can be repeated.

[0084] Alternatively, to reduce elastic deformation, the ratio of each interval can remain unchanged, but the first interval can be divided, and a third interval can be added between the divided first intervals. In the interval processed at a third speed lower than the first speed, it is expected that the elastic deformation will be relatively reduced. Therefore, compared to setting the first intervals together, dividing the first interval and setting the third interval in between can suppress the amount of elastic deformation even with the same ratio, thereby expecting the effect of chip breaking.

[0085] Furthermore, as an example of other interval ratio determination methods, we will explain the situation where the load exceeds a certain threshold. For example, if the first speed is too high, the excessive load may damage the tool or reduce the quality of the machined surface of the workpiece. Therefore, when the load exceeds a certain threshold, the interval ratios can be adjusted by reducing the first speed. For example, we can consider increasing the ratio of the first interval.

[0086] (3) The method of using predetermined parameters is explained. In the interval ratio determination unit 15, the interval ratio is determined by predetermined parameters. Multiple ratio setting values ​​can be preset, and the ratio to be used can be switched according to various thresholds. Examples of thresholds include feed rate, spindle speed, vibration frequency, vibration frequency, vibration amplitude, etc. In addition, various combinations of conditions and thresholds can be prepared in the form of tables or matrices for selection.

[0087] The ratio of each interval is determined by the methods described above, and a vibration waveform is generated by the vibration command generation unit 11 based on this ratio. The method for generating the vibration waveform and the following operations are the same as in Embodiment 1 described above, and therefore will not be explained here.

[0088] As described above, according to Embodiment 2, the ratio of each interval can be adjusted according to the situation. Therefore, vibration cutting can be performed using a vibration waveform corresponding to the machining situation, and the load during machining or the generated acceleration can be appropriately adjusted. Furthermore, by changing the ratio of each interval based on the load information generated in the tool or workpiece, each speed and each interval ratio can be automatically adjusted appropriately at all times, ensuring reliable chip breaking.

[0089] Implementation method 3.

[0090] In Embodiment 3, an embodiment using machine learning will be described. Here, we will mainly describe the aspects unique to Embodiment 3, and omit descriptions of aspects that are the same as those in Embodiments 1 and 2 described above. Figure 16 This is a block diagram illustrating the learning structure of the numerical control device involved in Embodiment 3.

[0091] exist Figure 16 In this process, the state acquisition unit 20 acquires state variables as input values ​​for machine learning during the machining process performed by vibration cutting. The state variables may include data representing machining conditions, data representing vibration conditions, data representing feed action content, and data representing the ratios of the first, second, and third intervals in one vibration cycle, i.e., interval ratios. The data representing machining conditions, for example, includes information about the aforementioned action commands and is acquired from the machining program parsing unit 10. The data representing vibration conditions includes information, for example, specifying the shape of the aforementioned vibration waveform and is acquired from the vibration command generation unit 11. The data representing feed action content includes, for example, the aforementioned feed commands and is acquired from the vibration command generation unit 11. The data representing the interval ratios is acquired from the vibration command generation unit 11.

[0092] The determination unit 22 determines whether the machining performed by vibration cutting is qualified or not based on the load information obtained by the load information acquisition unit 14. The determination result is output to the learning unit 21 as the qualified or unqualified machining data. As a method for determining whether it is qualified or not, it can determine whether there is idling based solely on the load information, or it can use the case where the load exceeds a certain threshold as a benchmark. In addition, it can use the statistical quantity of the load over a certain period of time for determination. For example, when there is a large fluctuation in the load, frequent speed changes may occur, and there is concern about the reduction in the quality of the machined surface, so the determination can be set to not.

[0093] The learning unit 21 learns the determination rules for the ratio of each interval based on a training dataset created from a combination of state variables output from the state acquisition unit 20 and processing pass / fail judgment data output from the judgment unit 22. That is, the learning unit 21 generates a trained model that infers the optimal ratio of each interval based on the state variables and processing pass / fail judgment data.

[0094] The correlation between the determination of whether a machining operation is satisfactory and the state variables is explained. As mentioned above, the state variables include data representing machining conditions, data representing vibration conditions, data representing the content of the feed action, and data representing the ratios of each interval. For example, in the case of high feed rate, a data point representing machining conditions, there is a tendency for the load accompanying the machining to increase even during non-vibration machining; therefore, it is assumed that the load will further increase during vibration cutting. Thus, the tendency to determine whether the machining operation is satisfactory is higher compared to the case of low feed rate.

[0095] Alternatively, in the case of a large vibration amplitude, which serves as an example of data representing vibration conditions, the tendency for chip breakage to occur and the determination of whether the machining is qualified becomes stronger due to the tendency for the swing area to become larger.

[0096] Furthermore, considering that in a feed command, which serves as an example of data representing feed action content, the difference in characteristics generated by a shaft that includes a vibration command can affect the determination of whether the machining is satisfactory. For example, when a shaft vibrates in the direction of gravity, the amplitude tends to decrease in the direction opposite to gravity, thus making chip breakage less likely. Alternatively, from a mechanical construction point of view, similarly, when a shaft vibrates in a structure carrying a heavy load, the amplitude tends to decrease, thus making chip breakage less likely. In either case, the tendency to determine whether the machining is satisfactory becomes stronger.

[0097] Learning Unit 21 learns the rules for determining the optimal ratio of each interval based on the tendency of the combination of state variables and processing qualification / failure judgment data as described above.

[0098] The learning algorithm used by Learning Department 21 can employ well-known algorithms such as teacher-led learning, teacherless learning, and reinforcement learning. Here, as an example, we will explain the application of neural networks.

[0099] Learning unit 21, for example, learns the optimal combination of ratios for each interval through so-called teacher-guided learning, according to a neural network model. Here, teacher-guided learning refers to the method of learning the features present in the learning data by providing the numerical control device 1 with a set of input and result (label) data, and inferring the result based on the input.

[0100] A neural network consists of an input layer composed of multiple neurons, an intermediate layer (hidden layer) composed of multiple neurons, and an output layer composed of multiple neurons. The intermediate layer can be one layer or more or more layers.

[0101] Figure 17This is a diagram illustrating an example of the structure of the neural network used in the numerical control device of Embodiment 3. For example, if it is Figure 17 The three-layer neural network shown takes multiple inputs into the input layer (X1-X3), multiplies their values ​​by weights W1 (w11-w16), and then inputs them into the intermediate layer (Y1-Y2). The result is then multiplied by weights W2 (w21-w26) and output from the output layer (Z1-Z3). The output result changes according to the values ​​of weights W1 and W2.

[0102] In embodiment 3, the neural network learns the optimal ratio of each interval through so-called teacher-guided learning, using learning data created based on a combination of state variables acquired by the state acquisition unit 20 and processing pass / fail judgment data output from the judgment unit 22. That is, the neural network adjusts the weights W1 and W2 so that the result output from the output layer after inputting state variables into the input layer is close to the processing pass / fail judgment data. The learning unit 21 generates and outputs a trained model by performing the above learning.

[0103] The trained model storage unit 23 stores the trained model output from the learning unit 21.

[0104] Next, use Figure 18 The learning process of CNC device 1 will be explained. Figure 18 This is a flowchart related to the learning process of the CNC device 1 in Embodiment 3. In step b1, the state acquisition unit 20 acquires state variables, and the determination unit 22 acquires load information to determine whether the machining is qualified or not, and outputs machining qualification or not determination data. Furthermore, it is assumed that the state variables and machining qualification or not determination data are acquired and output simultaneously, but as long as the state variables and machining qualification or not determination data can be associated and input, the state variables and machining qualification or not determination data can be acquired and output at different time points. In step b2, the learning unit 21, based on learning data created from the combination of the state variables acquired by the state acquisition unit 20 and the machining qualification or not determination data output from the determination unit 22, learns the optimal ratio of each interval through so-called teacher-guided learning, generating a trained model. In step b3, the trained model storage unit 23 stores the trained model generated by the learning unit 21.

[0105] Figure 19This is a block diagram illustrating the structure of the CNC device according to Embodiment 3 during inference. The inference unit 24 infers the optimal ratios of each interval using the trained model stored in the trained model storage unit 23. That is, the state variables obtained by the state acquisition unit 20 are input to the trained model, thereby enabling the output of the optimal ratios of each interval inferred based on the state variables. Furthermore, it has been described that the inference unit 24 outputs the optimal ratios of each interval using the trained model learned by the learning unit 21 of the CNC device 1, but it is also possible to obtain the trained model from external sources such as other CNC devices and output the optimal ratios of each interval based on the trained model.

[0106] Next, use Figure 20 The process of obtaining the optimal ratios for each interval using a trained model is explained. Figure 20 This is a flowchart related to the inference process of the CNC device 1 in Embodiment 3. In step c1, the state acquisition unit 20 acquires state variables. In step c2, the inference unit 24 inputs the state variables into the trained model stored in the trained model storage unit 23 to obtain the optimal ratios for each interval. In step c3, the inference unit 24 outputs the optimal ratios for each interval obtained from the trained model to the CNC device 1. In step c4, the CNC device 1 uses the output optimal ratios for each interval to calculate the vibration waveform. Thus, the state of machining using vibration cutting can be adjusted to the optimal level.

[0107] Furthermore, this embodiment describes the application of teacher-assisted learning in the learning algorithm used by the learning unit 21, but it is not limited to this. Regarding the learning algorithm, in addition to teacher-assisted learning, reinforcement learning, unassisted learning, or semi-teacher-assisted learning can also be applied. Additionally, deep learning, which involves learning by extracting the feature quantities themselves, can be used, or machine learning can be performed using other well-known methods such as genetic programming, inductive logic programming, and support vector machines.

[0108] As described above, according to Embodiment 3, the optimal ratio of each interval can be determined in accordance with the machining conditions performed by vibration cutting. Since learning is performed while machining is actually being carried out, an accurate method for determining the ratio of each interval is learned. Furthermore, since a trained model obtained through learning while machining is actually being performed is used, accurate inferences can be made. For example, in turning, the cutting tool is gradually fed in multiple stages to obtain the desired shape. For example, machining is performed in stages such as roughing, intermediate finishing, and finishing. Therefore, since similar machining paths are repeated, the ratio of each interval can be continuously optimized as machining progresses.

[0109] Here, the hardware structure of the CNC device 1 will be described. Figure 21 This diagram illustrates an example of the hardware structure of the numerical control device 1 according to Embodiments 1 to 3. The numerical control device 1 can... Figure 21 The processor 301, memory 302, and interface circuit 303 shown are implementations. Examples of the processor 301 are CPUs (also known as Central Processing Units, processing units, arithmetic units, microprocessors, microcomputers, processors, DSPs (Digital Signal Processors)) or system LSIs (Large Scale Integration). Examples of the memory 302 are RAM (Random Access Memory) and ROM (Read Only Memory).

[0110] The numerical control device 1 is implemented by the processor 301 reading and executing the program stored in the memory 302 for performing the actions of the numerical control device 1. Furthermore, this program can be described as instructing the computer to execute the sequence or method of the numerical control device 1. The memory 302 is also used as temporary storage when the processor 301 performs various processes. Moreover, regarding the functions of the numerical control device 1, some can be implemented using dedicated hardware, and some can be implemented using software or firmware.

[0111] The structures shown in the above embodiments represent a part of the content of the present invention, and can also be combined with other known technologies. Without departing from the scope of the present invention, appropriate combinations can be made, or parts of the structure can be omitted or modified.

[0112] Explanation of the label

[0113] 1. CNC device, 2. Feed unit, 3. Rotary unit, 10. Machining program analysis unit, 11. Vibration command generation unit, 12. Feed command output unit, 13. Rotary command output unit, 14. Load information acquisition unit, 15. Ratio determination unit for each interval, 16. Machining program, 20. Status acquisition unit, 21. Learning unit, 22. Judgment unit, 23. Training model storage unit, 24. Inference unit, E1, E2, E3 endpoints, G. Idle area, N. Number of vibrations, S1, S2, S3 starting points, V1. First speed, V2. Second speed, V3. Third speed, Va. Moving speed of the feed axis during non-vibration machining, W. Vibration amplitude, α. Surplus.

Claims

1. A numerical control device, comprising: A rotation command output unit that outputs a rotation command that causes the workpiece and the tool to rotate relative to each other; and The feed command output unit outputs a feed command that causes the workpiece and the tool to move relative to each other. The feed command can include a vibration command that alternately repeats forward and backward movements. The characteristic of this CNC device is that... One vibration in the vibration action command includes: The first interval is moved by the first speed, i.e., the speed during the forward movement; The second interval is moved by the second speed, i.e., the speed during the backward movement; and The third interval is the movement at a speed slower than the first speed during the forward movement, i.e., a third speed. It has a ratio determination unit for each interval, which determines the ratio of the first interval, the second interval, and the third interval in one vibration of the vibration action command. The interval ratio determination unit determines the ratio of the first interval, the second interval, and the third interval by combining a specified string and a numerical value for the ratio of each interval as described in the processing program.

2. A numerical control device, comprising: A rotation command output unit that outputs a rotation command that causes the workpiece and the tool to rotate relative to each other; and The feed command output unit outputs a feed command that causes the workpiece and the tool to move relative to each other. The feed command can include a vibration command that alternately repeats forward and backward movements. The characteristic of this CNC device is that... One vibration in the vibration action command includes: The first interval is moved by the first speed, i.e., the speed during the forward movement; The second interval is moved by the second speed, i.e., the speed during the backward movement; and The third interval is the movement at a speed slower than the first speed during the forward movement, i.e., a third speed. It has a ratio determination unit for each interval, which determines the ratio of the first interval, the second interval, and the third interval in one vibration of the vibration action command. The interval ratio determination unit determines the ratio of the first interval, the second interval, and the third interval based on a parameter representing the ratio of the first interval, the second interval, and the third interval.

3. The CNC device according to claim 2, characterized in that, The interval ratio determination unit determines the ratio of the first interval, the second interval, and the third interval based on a comparison of any one of the feed rate, spindle speed, vibration frequency, vibration number, and vibration amplitude with a threshold.

4. A numerical control device, comprising: A rotation command output unit that outputs a rotation command that causes the workpiece and the tool to rotate relative to each other; and The feed command output unit outputs a feed command that causes the workpiece and the tool to move relative to each other. The feed command can include a vibration command that alternately repeats forward and backward movements. The characteristic of this CNC device is that... One vibration in the vibration action command includes: The first interval is moved by the first speed, i.e., the speed during the forward movement; The second interval is moved by the second speed, i.e., the speed during the backward movement; and The third interval is the movement at a speed slower than the first speed during the forward movement, i.e., a third speed. It has a ratio determination unit for each interval, which determines the ratio of the first interval, the second interval, and the third interval in one vibration of the vibration action command. The interval ratio determination unit determines the ratio of the first interval, the second interval, and the third interval in one vibration of the vibration operation command based on load information representing the load generated in the workpiece and the tool during the vibration operation.

5. The CNC device according to any one of claims 1 to 4, characterized in that, The third interval is at least located between the first interval and the second interval.

6. The CNC device according to any one of claims 1 to 4, characterized in that, The third speed is the same as the relative movement speed of the workpiece and the tool during non-vibration machining.

7. A numerical control device, comprising: A rotation command output unit that outputs a rotation command that causes the workpiece and the tool to rotate relative to each other; and The feed command output unit outputs a feed command that causes the workpiece and the tool to move relative to each other. The feed command can include a vibration command that alternately repeats forward and backward movements. The characteristic of this CNC device is that... One vibration in the vibration action command includes: The first interval is moved by the first speed, i.e., the speed during the forward movement; The second interval is moved by the second speed, i.e., the speed during the backward movement; and The third interval is the movement at a speed slower than the first speed during the forward movement, i.e., a third speed. have: A state acquisition unit acquires state variables, which include at least one of the following: data representing processing conditions, data representing vibration conditions, and data representing feed action content; and The inference unit determines the ratio of the first interval, the second interval, and the third interval in one vibration of the vibration action command based on the output from the trained model when the state variables are input to the trained model.

8. The numerical control device according to claim 7, characterized in that, The trained model is learned using a training dataset that includes a combination of state variables and load information representing the load generated in the workpiece and the tool during vibration. The state variables include at least one of the following: data representing the machining conditions, data representing the vibration conditions, data representing the feed action content, and data representing the ratio of the first interval, the second interval, and the third interval in a single vibration during the vibration action command.

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