Numerical control device, control method, program and storage medium

Abstract

To provide a numerical control device, a control method, a program and a storage medium that can set rotational phase angles of a tool axis and a work axis in machining by synchronous rotation of the tool axis and the work axis.SOLUTION: A phase of a tool axis and a phase of a work axis at T2 are designated as designated phases β1 and α1, respectively. When an encoder detects that a phase of the work axis at T1 is a phase matching start phase α0, rotation speed of the tool axis is corrected so that a phase of the tool axis at T1, which is a phase matching start phase β0, becomes the designated phase β1 at T2 after phase matching time F has elapsed.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a numerical control device, a control method, a program, and a storage medium.

Background Art

[0002] The numerical control device described in Patent Document 1 performs machining by controlling the synchronous rotation of a work axis to which a work gear is attached and a tool axis to which a cutting tool is attached. The numerical control device performs a phase matching operation of matching the phase of the work axis to the phase of the tool axis by adding or subtracting the movement amount of the phase difference between the work axis and the tool axis to the movement amount of the work axis. Thereby, the numerical control device opposes the blade of the work to the blade groove of the tool and machines the gear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, although the relative phase difference between the tool axis and the work axis is corrected, the rotational phase angles of the tool axis and the work axis at the start of machining cannot be set. For this reason, there has been a problem that it becomes difficult to manage the wear of the blade of the tool.

[0005] An object of the present invention is to provide a numerical control device, a control method, a program, and a storage medium capable of setting the rotational phase angles of a tool axis and a work axis in machining by synchronous rotation of the tool axis and the work axis.

Means for Solving the Problems

[0006] According to a first aspect of the present invention, in a numerical control device that performs machining of a workpiece by controlling a machine tool including a tool spindle for mounting a tool and a workpiece spindle for rotating a table for fixing the workpiece, a synchronization control unit that performs control to synchronously rotate the tool spindle and the workpiece spindle, and during synchronous rotation of the tool spindle and the workpiece spindle by the synchronization control unit, based on the rotational phase angle of the tool spindle and the rotational phase angle of the workpiece spindle, a phase control unit that aligns the rotational phase angles of the tool spindle and the workpiece spindle is provided. The phase control unit includes a tool spindle phase angle setting unit that sets a set tool angle, which is the rotational phase angle of the tool spindle when the phase alignment ends, and a workpiece spindle phase angle setting unit that sets a set workpiece angle, which is the rotational phase angle of the workpiece spindle when the phase alignment ends. The rotational speed of the tool spindle and the rotational speed of the workpiece spindle are relatively controlled to perform the phase alignment such that the rotational phase angle of the tool spindle when the phase alignment of the tool spindle and the workpiece spindle ends becomes the set tool angle, and the rotational phase angle of the workpiece spindle becomes the set workpiece angle. A numerical control device is provided.

[0007] The numerical control device controls the synchronous rotation of the tool spindle and the workpiece spindle and performs machining of the workpiece. The numerical control device can set a set tool angle and a set workpiece angle, which are the rotational phase angles of the tool spindle and the workpiece spindle when the phase alignment ends, during the phase alignment of the tool spindle and the workpiece spindle. Therefore, the numerical control device can control the cutting edge of the tool that contacts the workpiece when machining of the workpiece by the tool starts, and can suppress wear of the cutting edge of the tool.

[0008] In the first aspect, the machine tool includes a feed axis that relatively moves the tool spindle and the workpiece spindle. The phase control unit includes a feed control unit that controls driving of the feed axis. The feed control unit drives the feed axis when the rotational phase angle of the tool spindle becomes the set tool angle and the rotational phase angle of the workpiece spindle becomes the set workpiece angle, and may start relative movement of the tool spindle and the workpiece spindle toward a position where the tool machines the workpiece. Since the numerical control device starts driving of the feed axis at the end of the phase alignment, the timing at which the tool contacts the workpiece can be kept constant for each machining.

[0009] In a first aspect, the numerical control device starts the alignment operation according to a phase command that instructs the alignment operation of the tool axis and the work axis. The tool axis phase angle setting unit sets the set tool angle based on a tool setting angle specifying variable that specifies the set tool angle in the phase command, and the work axis phase angle setting unit may set the set work angle based on a work setting angle specifying variable that specifies the set work angle in the phase command. Since the set tool angle and the set work angle are specified as variables in the phase command, the user does not need to perform an operation of setting the set tool angle and the set work angle in advance before executing the alignment operation.

[0010] In a first aspect, the phase control unit includes a start work angle calculation unit that calculates a start work angle, which is the rotational phase angle of the work axis at the start of the alignment, based on the set work angle, the work axis synchronization speed, which is the rotational speed of the work axis during machining controlled by the synchronization control unit, and the alignment time, which is a preset alignment time; a start tool angle calculation unit that calculates a start tool angle, which is the rotational phase angle of the tool axis when the work axis reaches the start work angle; an end tool angle calculation unit that calculates an end tool angle, which is the rotational phase angle that the tool axis reaches after the elapse of the alignment time from the start tool angle, based on the start tool angle, the tool axis synchronization speed, which is the rotational speed of the tool axis during machining controlled by the synchronization control unit, and the alignment time; a correction amount calculation unit that calculates the difference between the set tool angle and the end tool angle as a correction amount; and a tool speed control unit that controls the rotational speed of the tool axis so that the tool axis reaches the set tool angle after the elapse of the alignment time from the start tool angle based on the correction amount. The torque required for rotation of the tool axis is smaller than that of the work axis. Therefore, the numerical control device can smoothly perform the alignment of the tool axis and the work axis by correcting the end tool angle of the tool axis to the set tool angle.

[0011] In a first aspect, the machine tool may include a display device that displays information, and the synchronization control unit may include a notification unit that causes the display device to display a notification screen notifying that the tool spindle and the work spindle are rotating synchronously. The numerical control device can notify the user that the tool spindle and the work spindle are rotating synchronously by means of a notification screen displayed on the display device.

[0012] In a first aspect, the phase control unit may include a tool angle shift unit that changes the set tool angle based on the number of cutting edges of the tool, and the tool angle shift unit may change the set tool angle each time one or more machining operations of the work by the tool are performed. The numerical control device can sequentially shift the cutting edge that first contacts the work during machining by changing the set tool angle each time one or more machining operations of the work by the tool are performed, thereby suppressing tool wear.

[0013] In a first aspect, the work may be a machined gear. The numerical control device can perform machining of the machined gear by synchronous rotation of the tool spindle and the work spindle.

[0014] According to a second aspect of the present invention, there is provided a control method for a numerical control device that performs machining of a workpiece by controlling a machine tool including a tool spindle for mounting a tool and a workpiece spindle for rotating a table for fixing the workpiece, the control method including: a synchronization control step of performing control to synchronously rotate the tool spindle and the workpiece spindle; and a phase control step of aligning the rotation phase angles of the tool spindle and the workpiece spindle based on the rotation phase angle of the tool spindle and the rotation phase angle of the workpiece spindle during the synchronous rotation of the tool spindle and the workpiece spindle by the synchronization control step. The phase control step includes a tool spindle phase angle setting step of setting a set tool angle that is the rotation phase angle of the tool spindle when the phase alignment ends, and a workpiece spindle phase angle setting step of setting a set workpiece angle that is the rotation phase angle of the workpiece spindle when the phase alignment ends. A control method is provided, characterized in that the relative rotation speeds of the tool spindle and the workpiece spindle are controlled so that the rotation phase angle of the tool spindle when the phase alignment of the tool spindle and the workpiece spindle ends becomes the set tool angle and the rotation phase angle of the workpiece spindle becomes the set workpiece angle, thereby performing the phase alignment. Therefore, the same effect as that of the first aspect is achieved.

[0015] According to a third aspect of the present invention, there is provided a program for causing a numerical control device that performs machining of a workpiece by controlling a machine tool including a tool shaft for mounting a tool and a workpiece shaft for rotating a table for fixing the workpiece, the program causing a computer to execute a synchronization control step of performing control to rotate the tool shaft and the workpiece shaft in synchronization, and a phase control step of performing phase matching of the rotation phase angles of the tool shaft and the workpiece shaft based on the rotation phase angle of the tool shaft and the rotation phase angle of the workpiece shaft during the synchronous rotation of the tool shaft and the workpiece shaft by the synchronization control step. In the phase control step, a tool shaft phase angle setting step of setting a set tool angle that is the rotation phase angle of the tool shaft when the phase matching ends, and a workpiece shaft phase angle setting step of setting a set workpiece angle that is the rotation phase angle of the workpiece shaft when the phase matching ends are executed, and the rotation speed of the tool shaft and the rotation speed of the workpiece shaft are relatively controlled so that the rotation phase angle of the tool shaft when the phase matching of the tool shaft and the workpiece shaft ends becomes the set tool angle and the rotation phase angle of the workpiece shaft becomes the set workpiece angle, thereby performing the phase matching. Thus, the same effect as in the first aspect is achieved.

[0016] According to a fourth aspect of the present invention, there is provided a program for causing a numerical control device that performs machining of a workpiece by controlling a machine tool including a tool spindle for mounting a tool and a workpiece spindle for rotating a table for fixing the workpiece, the program causing a computer to execute a synchronization control step of performing control to synchronously rotate the tool spindle and the workpiece spindle, and a phase control step of performing phase matching of the rotational phase angles of the tool spindle and the workpiece spindle based on the rotational phase angle of the tool spindle and the rotational phase angle of the workpiece spindle during the synchronous rotation of the tool spindle and the workpiece spindle by the synchronization control step. In the phase control step, a tool spindle phase angle setting step of setting a set tool angle that is the rotational phase angle of the tool spindle when the phase matching ends, and a workpiece spindle phase angle setting step of setting a set workpiece angle that is the rotational phase angle of the workpiece spindle when the phase matching ends are executed, and the rotational speed of the tool spindle and the rotational speed of the workpiece spindle are relatively controlled so that the rotational phase angle of the tool spindle when the phase matching between the tool spindle and the workpiece spindle ends becomes the set tool angle and the rotational phase angle of the workpiece spindle becomes the set workpiece angle, thereby performing the phase matching. A storage medium storing the program is provided, and thus has the same effect as the first aspect.

Brief Description of Drawings

[0017]

Figure 1

Figure 2

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Figure 8

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Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0018] One embodiment of the present invention will be described. In the following description, the left - right, front - rear, and up - down directions indicated by arrows in the drawings are used. The left - right direction, front - rear direction, and up - down direction of the machine tool 1 are the X - axis direction, Y - axis direction, and Z - axis direction, respectively.

[0019] The machine tool 1 shown in FIG. 1 is a composite machining machine. The machine tool 1 can perform two - axis synchronous machining in addition to rotational machining and turning machining on the workpiece W. Rotational machining is a machining process in which the tool D is rotated and brought into contact with the workpiece W to cut the workpiece W. Turning machining is a machining process in which the workpiece W is rotated and the stationary tool D is brought into contact with the workpiece W to cut the workpiece W axially symmetrically. Two - axis synchronous machining is a machining process in which the tool D and the workpiece W are rotated simultaneously to cut the workpiece W by simultaneously driving the two axes of the tool shaft 8 (described later) and the workpiece shaft 82 (described later). The processed product of the workpiece W in this embodiment is, for example, a gear, and the tool D is, for example, a gear cutting tool.

[0020] Referring to FIGS. 1 and 2, the structure of the machine tool 1 will be described. The machine tool 1 includes a base portion 2, a carrier 12, a column 5, a spindle head 7, a tool shaft 8 (see FIG. 2), a workpiece holding device 80, an automatic tool changer 30 (hereinafter referred to as ATC 30), etc.

[0021] The base portion 2 is a rectangular box-shaped iron member that is long in the Y-axis direction. The base portion 2 includes a pedestal portion 4 on the rear side of the upper surface, a left front pedestal portion 18 on the left front side of the upper surface, and a right front pedestal portion 19 on the right front side of the upper surface. The pedestal portion 4 includes a pair of Y-axis rails 61, 62, a Y-axis ball screw 63 (see FIG. 2), a Y-axis motor 52 (see FIG. 3), etc. on the upper surface. The Y-axis rails 61, 62 and the Y-axis ball screw 63 extend in the Y-axis direction. The Y-axis ball screw 63 is provided between the Y-axis rails 61, 62.

[0022] The carrier 12 is provided on the pedestal portion 4 and is movable along the Y-axis rails 61, 62. The carrier 12 includes a nut (not shown) on the lower surface. The nut is screwed onto the Y-axis ball screw 63. The Y-axis motor 52 rotates the Y-axis ball screw 63. The carrier 12 moves in the Y-axis direction together with the nut. The carrier 12 includes a pair of X-axis rails 71, 72, an X-axis ball screw 73, an X-axis motor 51, etc. on the upper surface. The X-axis rails 71, 72 and the X-axis ball screw 73 extend in the X-axis direction. The X-axis ball screw 73 is provided between the X-axis rails 71, 72.

[0023] The column 5 is provided on the carrier 12 and is movable along the X-axis rails 71, 72. The column 5 includes a nut (not shown) on the lower surface. The nut is screwed onto the X-axis ball screw 73. The X-axis motor 51 rotates the X-axis ball screw 73. The column 5 moves in the X-axis direction together with the nut and is movable in the Y-axis direction via the carrier 12. The column 5 includes a pair of Z-axis rails (not shown), a Z-axis ball screw (not shown), a Z-axis motor 53 (see FIG. 3), etc. on the front surface. The Z-axis rails and the Z-axis ball screw extend in the Z-axis direction. The Z-axis ball screw is provided between the pair of Z-axis rails.

[0024] The spindle head 7 is movable along the Z-axis rail. The spindle head 7 is provided with a nut (not shown) on the back surface. The nut is screwed onto the Z-axis ball screw. The Z-axis motor 53 rotates the Z-axis ball screw. The spindle head 7 moves in the Z-axis direction together with the nut and is movable in the X-axis and Y-axis directions via the column 5 and the carrier 12. The tool spindle 8 is provided on the spindle head 7. The tool spindle 8 is provided with a tool mounting hole (not shown) at the lower end. The tool mounting hole is located at the lower part of the tool spindle 8. The tool D is mounted in the tool mounting hole. The tool spindle motor 54 rotates the tool spindle 8. The tool spindle motor 54 is provided on the upper part of the spindle head 7.

[0025] The workpiece holding device 80 includes a left fixing part 88, a right fixing part 89, a table 81, a workpiece spindle 82, a workpiece spindle motor 56, a tilt motor 57, etc. The left fixing part 88 is fixed to the upper surface of the left front pedestal part 18. The right fixing part 89 is fixed to the upper surface of the right front pedestal part 19. The table 81 includes a horizontal part 81A, a left connecting part 81B, and a right connecting part 81C. The workpiece spindle 82 is rotatably provided at approximately the center of the table 81. The workpiece spindle motor 56 is provided on the lower surface side of the horizontal part 81A. The workpiece spindle 82 is connected to the rotating shaft of the workpiece spindle motor 56. The rotating shaft of the workpiece spindle motor 56 is orthogonal to the horizontal part 81A. The workpiece spindle 82 can hold the workpiece W at the upper part using a jig (not shown).

[0026] The left connecting part 81B extends obliquely upward to the left from the horizontal part 81A and is connected to the left fixing part 88. The left fixing part 88 rotatably supports the left connecting part 81B around an axis extending in the left-right direction. The right connecting part 81C extends obliquely upward to the right from the horizontal part 81A and is connected to the right fixing part 89. The right fixing part 89 rotatably supports the right connecting part 81C around an axis extending in the left-right direction. The tilt motor 57 is fixed to the right fixing part 89. The rotating shaft of the tilt motor 57 is connected to the right connecting part 81C. The tilt motor 57 rotates the table 81 around an axis extending in the left-right direction. The workpiece W held by the workpiece spindle 82 rotates around the axis of the workpiece spindle 82 by the drive of the workpiece spindle motor 56. The workpiece W rotates around an axis perpendicular to the horizontal part 81A by the drive of the workpiece spindle motor 56 regardless of the rotation of the table 81 by the tilt motor 57.

[0027] The ATC 30 includes a tool magazine 31, a magazine support member 32, a magazine motor 55, a drive gear 35, etc. The magazine support member 32 is in an elliptical ring shape and is attached to the column 5 with the spindle head 7 and the column 5 arranged inside. The tool magazine 31 is attached along the outer periphery of the magazine support member 32. The tool magazine 31 includes a chain 34 and a plurality of pots 37. The chain 34 is movably attached along the outer periphery of the magazine support member 32. The plurality of pots 37 are respectively attached to the chain 34. The pot 37 can hold the tool D. The pot 37 is formed in an arm shape and is attached so as to be swingable in the front-rear direction.

[0028] The magazine motor 55 is attached to the upper part of the magazine support member 32. The drive shaft of the magazine motor 55 is orthogonal to the upper surface of the magazine support member 32. The drive shaft of the magazine motor 55 can rotate in the forward and reverse directions respectively. The drive gear 35 is attached to the drive shaft of the magazine motor 55. The drive gear 35 rotates together with the drive shaft of the magazine motor 55. The drive gear 35 meshes with the chain 34 of the tool magazine 31. The chain 34 moves in either the forward or reverse direction along the outer periphery of the magazine support member 32 by the drive of the drive gear 35. Therefore, the pot 37 moves along the outer periphery of the magazine support member 32 together with the chain 34. The position of the pot 37 located at the lowermost part of the tool magazine 31 is the tool exchange position. The tool exchange position is the position closest to the tool shaft 8. The ATC 30 exchanges the next tool with the current tool. The next tool indicates the tool to be used for the next machining and is the tool held by the pot 37 at the tool exchange position. The current tool is the tool attached to the tool shaft 8 and indicates the tool currently being machined.

[0029] Referring to FIG. 3, the electrical configuration of the machine tool 1 will be described. The machine tool 1 includes a numerical control device 20. The numerical control device 20 includes a CPU 21, a ROM 22, a RAM 23, a storage device 24, a bus 25, an input / output interface 26, and the like. The CPU 21 comprehensively controls the operation of the machine tool 1. The ROM 22 stores various programs such as a main program, a two-axis synchronous control program, and a phase alignment control program (described later). The main program is a program for executing the main processing of the numerical control device 20. The two-axis synchronous control program is a program for controlling the two-axis synchronous machining (described later). The phase alignment control program is a program for executing the phase alignment control process (refer to FIG. 11) described later. The RAM 23 stores various data. The storage device 24 is a non-volatile memory and stores various data in addition to the NC program. The NC program is composed of a plurality of blocks. Each block contains various instructions. The CPU 21 can store the NC program input by the operator via the input unit 28 of the operation panel 27, as well as the NC program read by external input, etc. in the storage device 24.

[0030] The machine tool 1 further includes an operation panel 27. The operation panel 27 is provided, for example, on a cover (not shown) covering the machine tool 1. The operation panel 27 has an input unit 28 and a display unit 29. The input unit 28 receives various inputs related to the operation and settings of the machine tool 1. The display unit 29 displays various screens such as a setting screen and an operation screen of the machine tool 1. The input unit 28 and the display unit 29 are electrically connected to the input / output interface 26.

[0031] The drive circuit 41 drives the X-axis motor 51. The encoder 51A is connected to the X-axis motor 51 and the input / output interface 26. The encoder 51A detects the rotation amount of the X-axis motor 51 and inputs a detection signal to the CPU 21 via the input / output interface 26. The drive circuit 42 drives the Y-axis motor 52. The encoder 52A is connected to the Y-axis motor 52 and the input / output interface 26. The encoder 52A detects the rotation amount of the Y-axis motor 52 and inputs a detection signal to the CPU 21 via the input / output interface 26. The drive circuit 43 drives the Z-axis motor 53. The encoder 53A is connected to the Z-axis motor 53 and the input / output interface 26. The encoder 53A detects the rotation amount of the Z-axis motor 53 and inputs a detection signal to the CPU 21 via the input / output interface 26.

[0032] The drive circuit 44 drives the tool axis motor 54. The encoder 54A is connected to the tool axis motor 54 and the input / output interface 26. The encoder 54A detects the rotation amount of the tool axis motor 54 and inputs a detection signal to the CPU 21 via the input / output interface 26. The drive circuit 45 drives the magazine motor 55. The encoder 55A is connected to the magazine motor 55 and the input / output interface 26. The encoder 55A detects the rotation amount of the magazine motor 55 and inputs a detection signal to the CPU 21 via the input / output interface 26. The drive circuit 46 drives the work axis motor 56. The encoder 56A is connected to the work axis motor 56 and the input / output interface 26. The encoder 56A detects the rotation amount of the work axis motor 56 and inputs a detection signal to the CPU 21 via the input / output interface 26.

[0033] The drive circuit 47 drives the tilt motor 57. The encoder 57A is connected to the tilt motor 57 and the input / output interface 26. The encoder 57A detects the rotation amount of the tilt motor 57 and inputs a detection signal to the CPU 21 via the input / output interface 26. The X-axis motor 51, Y-axis motor 52, Z-axis motor 53, tool axis motor 54, magazine motor 55, work axis motor 56, and tilt motor 57 are servo motors. The drive circuit 48 drives the clamp device 58. The clamp device 58 is provided on the back side of the table 81. The clamp device 58 fixedly holds the work axis 82.

[0034] Referring to FIGS. 4 to 5, two-axis synchronous machining will be described. Two-axis synchronous machining is a machining method in which, for example, in skiving, hobbing, turn-milling, etc., a free form is applied to the machining surface (the surface to be machined) of the workpiece W while the tool axis 8 and the work axis 82 rotate synchronously. As shown in FIG. 4, for the sake of convenience of explanation, the axial direction D1 of the tool axis 8 and the axial direction W1 of the work axis 82 are assumed to be parallel to each other. Therefore, the axial direction D1 and the axial direction W1 may be directions intersecting each other. The work axis 82 holds the workpiece W with a jig on the upper holding surface, and the tool axis 8 mounts the tool D in the tool mounting hole. The tool D faces downward. The tool D is provided with a plurality of tips (for example, eight tips B1 to B8) on the side surface. The machine tool 1 sets the direction of the virtual straight line A connecting the axial position of the work axis 82 and the axial position of the tool axis 8 as the X-axis direction for the sake of convenience of explanation. The numerical control device 20 controls the tool axis 8 to be movable in the X-axis direction with respect to the work axis 82. Incidentally, the numerical control device 20 may control the work axis 82 to be movable in the X-axis direction with respect to the tool axis 8.

[0035] In the following description, for the sake of simplification, attention is paid to the tip B1 of the tool D, and the operation when the tip B1 machines the workpiece W will be mainly described. The cutting edge of the tip B1 hits the machining surface of the workpiece W from the side. The first cutting position of the tip B1 is P1. The numerical control device 20 rotates the work axis 82 and the tool axis 8 in opposite directions to each other. The numerical control device 20 rotates the work axis 82 and the tool axis 8 synchronously so that the following equation (1) holds. Sw / R + E = St / Q ···(1) Sw: Rotational speed of the work axis 82, St: Rotational speed of the tool axis 8, R: Number of tips of the tool D, E: Rotational speed difference, Q: Shape number, etc. The shape number is the number of divisions for dividing the work W on a virtual circumference, and is the number of each shape part obtained by the division. Each of the divided shapes is a surface target shape with respect to each other. The virtual circle is a circular locus on which the position of the tool tip against the machining surface of the work W by the tip B1 moves during the synchronous rotation of the work axis 82 and the tool axis 8. The rotational speed difference E is a value sufficiently smaller than (Sw / R) and (St / Q). Due to the rotational speed difference E, a time difference occurs in which the tip B of the tool D hits the machining surface of the work W. When the rotational speed difference E is 0, the work W is machined into a polygonal shape by normal polygon machining. The time difference generates a phase difference Δθ. Due to the phase difference Δθ, the position of the tool tip of B1 shifts from P1 to P2. When the synchronous rotation of the work axis 82 and the tool axis 8 continues, the position of the tool tip of B1 moves on a virtual circumference centered on the rotation center of the work W. The numerical control device 20 forms a minute free form on the virtual circumference of the work W by controlling the position of the tool D in the X-axis direction every cycle in which the tip B1 passes on the virtual straight line A.

[0036] When the work axis 82 and the tool axis 8 are synchronously rotated respectively, for example, as shown in FIG. 5, the position of the tool tip of the tool D sequentially moves to P1, P2, P3, P4,... every cycle in which the tip B1 passes on the virtual straight line A. The numerical control device 20 moves the tool D in the X-axis direction so as to reach the target position every cycle in which the tip B1 passes on the virtual straight line A. The tool tip positions P1, P2, P3, P4,... change their positions in the radial direction of the virtual circle. Therefore, the numerical control device 20 can form a free form with high precision on the machining surface of the work W. The free form formed by the tip B1 is, for example, a broken line shape bent at the tool tip positions P1 to P4.

[0037] Similarly, for the chip B2 of the tool D, each time the chip B2 passes on the virtual straight line A, the position per blade strike of the tool D sequentially moves as P5, P6, P7, P8 ···. Therefore, a similar shape is formed by the chip B2 in a portion different from the portion where the shape is formed by the chip B1 in the circumferential direction of the workpiece W. Note that, for convenience of explanation, FIG. 5 shows a relatively small number of shapes formed on the workpiece W. The same applies to the chips B3 to B8 of the tool D. Therefore, the numerical control device 20 can form a free shape corresponding to the number of shapes in the circumferential direction of the workpiece W by two-axis synchronous machining.

[0038] Referring to FIGS. 6 to 9, the phase matching control will be described. The phase matching control is control for performing phase matching in the absolute phases of the tool axis 8 and the workpiece axis 82. In two-axis synchronous machining, with the workpiece axis 82 and the tool axis 8 rotating synchronously, the tool D is moved in the cutting direction with respect to the workpiece W by the feed axes (X-axis, Y-axis, Z-axis), thereby machining the workpiece W. Among the chips B1 to B8 of the tool D, the chip that first contacts the workpiece W varies for each machining due to various factors such as the rotation start timing of the tool axis 8, the phase at the start of rotation, the rotation start timing of the workpiece axis 82, the phase at the start of rotation, and the movement start timing of the tool axis 8 by the feed axis. The numerical control device 20 can set the chip that first contacts the workpiece W among the chips B1 to B8 of the tool D to a specific chip by performing phase matching control.

[0039] For example, as shown in FIG. 6, at T0, the workpiece axis 82 and the tool axis 8 are in a state of synchronous rotation at a predetermined rotation ratio. In the phase matching control process described later, the numerical control device 20 designates the phase of the workpiece axis 82 at T2 as α1 and the phase of the tool axis 8 as β1. The phase matching control is control for correcting the phase of the tool axis 8 to the designated β1 when the phase of the workpiece axis 82 is α1 at T2 and the phase of the tool axis 8 is uncorrected and is β2. Note that, without correcting the phase of the workpiece axis 82 and correcting the phase of the tool axis 8, since the workpiece W is heavier than the tool D in normal machining, correcting the phase of the tool axis 8 can reduce the torque required for correction compared to correcting the phase of the workpiece axis 82.

[0040] The numerical control device 20 corrects the phase of the tool axis 8 by performing control to temporarily slow down the rotation speed of the tool axis 8 during the phase matching time F. The phase matching time F is the time required for a process of temporarily decelerating the rotation speed of the tool axis 8 and then returning to the original speed so that the phase of the tool axis 8 at T2 is corrected from β2 to β1. Correcting the phase of the tool axis 8 by decelerating the rotation speed of the tool axis 8 is because if it is corrected by accelerating, the rotation speed of the tool axis 8 may reach the maximum speed. Therefore, the numerical control device 20 corrects the phase of the tool axis 8 by decelerating the rotation speed and prevents exceeding the upper limit of the rotation speed in terms of the performance of the tool axis motor 54. The numerical control device 20 sets the timing to start the correction based on the phase of the work axis 82 so that the phase of the tool axis 8 becomes β1 at T2. The numerical control device 20 sets T1, which is F minutes before T2, as the timing to start the correction.

[0041] As shown in FIG. 7, the phase matching time F is obtained by doubling the phase matching time constant Fx. The phase matching time constant is the sum of the time constant t1 and the time constant t2, which will be described later. The time constant t1 is the time required for the rotational speed of the tool shaft 8 to start decelerating from V2 and reach T1A at a constant deceleration rate within the time T1. The time constant t2 is the time required from T1A until the deceleration rate becomes 0 and the rotational speed of the tool shaft 8 becomes a constant V1, which is lower than V2. The process of accelerating the rotational speed of the tool shaft 8 from V1 to V2 during T1B to T1C to T2 is also performed with the same phase matching time constant Fx. That is, the numerical control device 20 decelerates the rotational speed of the tool shaft 8 using the phase matching time constant Fx from T1 to T1A to T1B, and then accelerates the rotational speed of the tool shaft 8 using the phase matching time constant Fx from T1B to T1C to T2, thereby correcting the phase of the tool shaft 8 at T2 from β2 to β1. Incidentally, in the timing chart of the phase and time of the tool shaft 8, the area Sa of the portion surrounded by β0, β1, and β2 corresponds to the correction amount of the phase of the tool shaft 8. Also, in the timing chart of the rotational speed and time of the tool shaft 8, the area Sb of the portion surrounded by V2 and the rotational speed in the interval from T1 to T2 corresponds to the correction amount of the phase of the tool shaft 8.

[0042] As shown in FIG. 6, the numerical control device 20 obtains the phase difference corresponding to the distance traveled by the work shaft 82 during the phase matching time F by requiring the phase matching time F for the rotational speed of the work shaft 82. The numerical control device 20 obtains the phase α0 of the work shaft 82 at T1 by subtracting the obtained phase difference from the phase α1 of the work shaft 82 at T2. The phase of the work shaft 82 when it is α0 is referred to as the phase matching start phase α0. The numerical control device 20 sets T1 as the time when the phase of the work shaft 82 is α0 and starts correcting the phase of the tool shaft 8.

[0043] When determining T1, the numerical control device 20 detects, using the encoder 56A, the timing at which the phase of the work axis 82 becomes the phase alignment start phase α0. Since the encoder 56A detects the phase of the work axis 82 based on the pulse period obtained by dividing the phase in the circumferential direction into a plurality of parts, it is difficult to detect the exact timing at which the phase of the work axis 82 exactly becomes the phase alignment start phase α0. Therefore, when an output that straddles a larger value and a smaller value than the phase alignment start phase α0 is obtained for the phase of the work axis 82 in two consecutive pulse periods, the numerical control device 20 determines that the phase of the work axis 82 has reached the phase alignment start phase α0. The numerical control device 20 calculates, by linear interpolation, the phase alignment start phase β0, which is the phase of the tool axis 8 when the work axis 82 reaches the phase alignment start phase α0, based on the phase of the work axis 82 and the phase of the tool axis 8 in the pulse periods before and after straddling the phase alignment start phase α0, according to the following equation (2). β0 = S1 + {(r b - r a ) / r b}(S2 - S1) ···(2) Here, β0: Phase alignment start phase of the tool axis 8, S1: Phase of the tool axis 8 detected in the pulse period immediately before straddling the phase alignment start phase α0, S2: Phase of the tool axis 8 detected in the pulse period immediately after straddling the phase alignment start phase α0, r a : Phase difference between α0 and S1, r b : Phase difference between S2 and S1.

[0044] Based on the phase alignment start phase β0 of the tool axis 8 obtained by equation (2), the numerical control device 20 calculates, by equation (3), the phase β2 without correction, which is the phase of the tool axis 8 at T2 when no phase correction is performed. β2 = β0 + V2 × F ···(3) Here, β2: Phase without correction of the tool axis 8, V2: Rotational speed of the tool axis 8, F: Phase alignment time.

[0045] Based on the phase β2 without correction of the tool axis 8 obtained by equation (3), the numerical control device 20 calculates, by equation (4), the correction amount Δω for correcting the phase of the tool axis 8 from the phase β2 without correction to the specified phase β1. Δθ = β1 - β2 ···(4) Furthermore, Equation (4) is represented by the following four equations according to the conditions.

[0046] (A) When the rotation direction of the tool axis 8 is the positive direction and (β1 - β2) ≥ 0, Δθ = (β1 - β2) - 360 ···(4 - 1) Furthermore, when the rotation direction of the tool axis 8 is the positive direction, it means that the phase of the tool axis 8 corresponding to the detection result obtained from the encoder 56A increases from 0° to 360°. In this case, as shown in Fig. 8(A), the inclination of the phase of the tool axis 8 between β0 - β1 is larger than the inclination of the phase of the tool axis 8 between β0 - β2. That is, the rotation speed from the phase alignment start phase β0 to the specified phase β1 is accelerated compared to the rotation speed from the phase alignment start phase β0 to the uncorrected phase β2. In this case, the phase alignment start phase β0 is set to the phase alignment start phase β0A at T0A where the rotation phase of the tool axis 8 is one cycle (-360°) earlier than T1. As a result, the inclination of the phase of the tool axis 8 between β0A - β1 is smaller than the inclination of the phase of the tool axis 8 between β0 - β2. That is, the rotation speed from the phase alignment start phase β0A to the specified phase β1 is decelerated compared to the rotation speed from the phase alignment start phase β0 to the uncorrected phase β2. The numerical control device 20 can correct the phase of the tool axis 8 without the rotation speed of the tool axis 8 reaching the maximum speed. Furthermore, in the case of (A), the phase alignment time F is the time obtained by adding the rotation time for one cycle of the tool axis 8.

[0047] (B) When the rotation direction of the tool axis 8 is the positive direction and (β1 - β2) < 0, Δθ = (β1 - β2) ···(4 - 2) As shown in Fig. 8(B), the inclination of the phase of the tool axis 8 between β0 - β1 is smaller than the inclination of the phase of the tool axis 8 between β0 - β2. That is, the rotation speed from the phase alignment start phase β0 to the specified phase β1 is decelerated compared to the rotation speed from the phase alignment start phase β0 to the uncorrected phase β2. The numerical control device 20 can correct the phase of the tool axis 8 without the rotation speed of the tool axis 8 reaching the maximum speed.

[0048] (C) When the rotation direction of the tool shaft 8 is the reverse direction and (β1 - β2) ≥ 0, Δθ = (β1 - β2) ···(4 - 3) Furthermore, when the rotation direction of the tool shaft 8 is the reverse direction, it means that the phase of the tool shaft 8 corresponding to the detection result obtained from the encoder 56A decreases from 360° to 0°. In this case, as shown in Fig. 8(C), the inclination of the phase of the tool shaft 8 between β0 - β1 is smaller than the inclination of the phase of the tool shaft 8 between β0 - β2. That is, the rotational speed from the phase alignment start phase β0 to the specified phase β1 is decelerated compared to the rotational speed from the phase alignment start phase β0 to the uncorrected phase β2. Therefore, the numerical control device 20 can correct the phase of the tool shaft 8 without the rotational speed of the tool shaft 8 reaching the maximum speed.

[0049] (D) When the rotation direction of the tool shaft 8 is the reverse direction and (β1 - β2) < 0, Δθ = (β1 - β2) + 360 ···(4 - 4) As shown in Fig. 8(D), the inclination of the phase of the tool shaft 8 between β0 - β1 is larger than the inclination of the phase of the tool shaft 8 between β0 - β2. The rotational speed from the phase alignment start phase β0 to the specified phase β1 is accelerated compared to the rotational speed from the phase alignment start phase β0 to the uncorrected phase β2. Therefore, as the phase alignment start phase β0, it is set to the phase alignment start phase β0B at T0A which is one cycle (+360°) earlier than T1 of the rotational phase of the tool shaft 8. As a result, the inclination of the phase of the tool shaft 8 between β0B - β1 is smaller than the inclination of the phase of the tool shaft 8 between β0 - β2. That is, the rotational speed from the phase alignment start phase β0B to the specified phase β1 is decelerated compared to the rotational speed from the phase alignment start phase β0 to the uncorrected phase β2. Therefore, the numerical control device 20 can correct the phase of the tool shaft 8 without the rotational speed of the tool shaft 8 reaching the maximum speed. In addition, in the case of (D), the phase alignment time F is the time obtained by adding the rotational time for one cycle of the tool shaft 8.

[0050] The numerical control device 20 controls the acceleration and deceleration of the rotational speed of the tool axis 8 at the phase alignment time F based on the correction amount Δω obtained by the formula (4) as follows. As shown in FIG. 9(A), the area Sb of the portion surrounded by V2 and the rotational speed in the section of T1 to T2 of the correction amount Δω of the tool axis 8 is multiplied by (t1 + t2) at the correction speed before filter application of the tool axis 8 so that the area Sb becomes the correction amount Δω and distributed. Next, as shown in FIG. 9(B), a moving average filter with a time constant t1 during deceleration between T1 and T1A is used for the correction speed before filter application of the tool axis 8. Further, as shown in FIG. 9(C), a moving average filter with a time constant t2 during deceleration between T1A and T1B is used for the correction speed of the tool axis 8. Thereby, the numerical control device 20 can generate the correction speed of the tool axis 8 so that the rotational speed of the tool axis 8 smoothly decreases from V2 to V1 and then smoothly increases from V1 to V2 at the phase alignment time F.

[0051] At T2 when the correction is completed, when the phase of the work axis 82 becomes α1, the phase of the tool axis 8 becomes β1. The numerical control device 20 drives the feed axis at T2. The moving speed of the feed axis accelerates and reaches Va at T3. The numerical control device 20 maintains the moving speed of the feed axis at Va after T3 and moves the tool D in the cutting direction toward the work W. At T4, the tool D contacts the work W. At this time, the phase of the tool axis 8 is β3. The numerical control device 20 controls the phase of the tool axis 8 at T4 to be located at β3 by positioning the phases of the work axis 82 and the tool axis 8 at T2 at the absolute phases α1 and β1, respectively. Therefore, when the numerical control device 20 repeats machining under the same conditions, it can control the phase of the tool axis 8 so that the tip that first contacts the work W among the tips B1 to B8 of the tool D always becomes a specific tip.

[0052] With reference to FIGS. 10 to 12, the operation of the phase alignment control will be described. The CPU 21 of the numerical control device 20 uses the NC program 100 (see FIG. 10) in the machining of the work W. The NC program 100 is stored in the storage device 24.

[0053] Figure 10 is a part of the NC program 100 and is a phase alignment program for executing phase alignment control processing. The "M142" command in the phase alignment program is a command for specifying the ratio of the rotation speed of the tool axis 8 to the work axis 82. The ratio is input to the parts of "U_" and "V_". For example, in the case of "M142 U3V2", "Rotation speed of tool axis 8: Rotation speed of work axis 82 = 3:2" is specified. Specifically, for example, if the rotation speed of the work axis 82 is S100 min -1 then the rotation speed of the tool axis 8 is S150 min -1 is specified.

[0054] The "M303" command in the phase alignment program is a command for rotating the work axis 82 in the positive direction at the specified rotation speed and synchronously rotating the tool axis 8 at the ratio specified by the "M142" command in synchronization with the work axis 82. The rotation speed is input to the part of "S_". For example, in the case of "M303 S100", it instructs "Start rotating the work axis 82 in the positive direction at S100 min -1 . Note that the positive direction in the rotation direction of the work axis 82 is, for example, the clockwise direction in the plan view of the machine tool 1 (see Fig. 4). The tool axis 8 rotates in the direction opposite to the rotation direction of the work axis 82 (for example, the counterclockwise direction in the plan view of the machine tool 1) in synchronization with the work axis 82.

[0055] The "M304" command is a command for rotating the work axis 82 in the reverse direction at the specified rotation speed and synchronously rotating the tool axis 8 at the ratio specified by the "M142" command in synchronization with the work axis 82. Therefore, in the phase alignment program, either the "M303" command or the "M304" command is issued. The rotation speed is input to the part of "S_". For example, in the case of "M304 S100", it instructs "Start rotating the work axis 82 in the reverse direction at S100 min -1 . Note that the reverse direction in the rotation direction of the work axis 82 is, for example, the counterclockwise direction in the plan view of the machine tool 1. The tool axis 8 rotates in the direction opposite to the rotation direction of the work axis 82 (for example, the clockwise direction in the plan view of the machine tool 1) in synchronization with the work axis 82. Note that the definitions of the positive direction and the reverse direction in the rotation direction of the work axis 82 may be in the directions opposite to the above description.

[0056] The "G333" command of the phase alignment program is a command that performs the movement of the feed axis after aligning the phases of the work axis 82 and the tool axis 8 during synchronous rotation to the specified phases respectively. "X_", "Y_", and "Z_" are parameters that specify the coordinates at which the movement operations of the X-axis, Y-axis, and Z-axis are completed respectively. "Q_" is a parameter that specifies the specified phase α1 of the work axis 82. "R_" is a parameter that indicates whether or not to perform phase alignment. "E_" is a parameter that specifies the specified phase β1 of the tool axis 8. "F_" is a parameter that specifies the movement speed Va of the feed axis.

[0057] Referring to FIG. 11, the phase alignment control process executed by the CPU 21 will be described. When an operator starts the machine tool 1 and selects the NC program 100 for machining the work W at the input unit 28, the CPU 21 reads out the NC program 100 from the storage device 24. When the operator presses the execution button (not shown) of the input unit 28, the CPU 21 starts the main program from the ROM 22 and executes the main process for the NC program 100. In the main process, the CPU 21 interprets the commands of the NC program 100 one block at a time and machines the work W. As shown in FIG. 12, various information in the machining of the work W is displayed on the display screen 120 of the display unit 29. The rotational speed (main spindle rotational speed) of the tool axis 8 is displayed in the main spindle rotational speed display area 125 within the display screen 120. When not in the mode where two-axis synchronous machining is performed, the information on the rotational speed of the work axis 82 is not displayed.

[0058] The position alignment control program and the two-axis synchronization control program are executed during the execution of the main program. As shown in FIG. 10, when the instruction interpreted by the CPU 21 is the "M142" instruction, the CPU 21 stores in the storage device 24 the ratio of the rotational speeds of the work axis 82 and the tool axis 8 described in the "M142" instruction. The CPU 21 shifts to the mode for performing two-axis synchronous machining (FIG. 12, S1), and in addition to the portion for displaying the rotational speed (main spindle rotational speed) of the tool axis 8 in the main spindle rotational speed display area 125 within the display screen 120, provides a portion for displaying the rotational speed (turning main spindle rotational speed) of the work axis 82 (see FIG. 12). Thereby, the CPU 21 notifies that it is the mode in which two-axis synchronous machining is performed.

[0059] When the instruction interpreted by the CPU 21 is the "M303" instruction, the CPU 21 starts the rotation of the work axis 82 in the forward direction at the rotational speed described in the "M303" instruction. When the instruction interpreted by the CPU 21 is the "M304" instruction, the CPU 21 starts the rotation of the work axis 82 in the reverse direction at the rotational speed described in the "M304" instruction. The CPU 21 multiplies the rotational speed of the work axis 82 described in the "M303" or "M304" instruction by the ratio stored in the storage device 24 to calculate the rotational speed of the tool axis 8. In the case of the "M303" instruction, the CPU 21 starts the synchronous rotation of the tool axis 8 in the reverse direction at the calculated rotational speed, and in the case of the "M304" instruction, the CPU 21 starts the synchronous rotation of the tool axis 8 in the forward direction at the calculated rotational speed. The CPU 21 displays the rotational speed of the tool axis 8 based on the detection result of the encoder 54A in the portion for displaying the rotational speed (main spindle rotational speed) of the tool axis 8 in the main spindle rotational speed display area 125 (FIG. 12, S2). The CPU 21 displays the rotational speed of the work axis 82 based on the detection result of the encoder 56A in the portion for displaying the rotational speed (main spindle rotational speed) of the tool axis 8 in the main spindle rotational speed display area 125 (FIG. 12, S2).

[0060] When the instruction interpreted by the CPU 21 is the "G333" instruction, the CPU 21 executes the position alignment process. As shown in FIG. 11, the CPU 21 calculates the position alignment start phase α0 of the work axis 82 based on the rotational speed of the work axis 82 and the position alignment time F (S11).

[0061] Based on the detection result of the encoder 56A, the CPU 21 determines whether the phase of the work axis 82 has reached the phase alignment start phase α0 (S13). If it has not reached, it waits (S13: NO). When a detection result is obtained from the encoder 56A that the phase of the work axis 82 straddles a larger value and a smaller value than the phase alignment start phase α0, the CPU 21 determines that the phase of the work axis 82 has reached the phase alignment start phase α0 (S13: YES). The CPU 21 calculates the phase alignment start phase β0, which is the phase of the tool axis 8 when the work axis 82 reaches the phase alignment start phase α0, based on equation (2) (S15).

[0062] When the CPU 21 does not correct the phase of the tool axis 8, it calculates the non-correction phase β2, which is the phase of the tool axis 8 at the completion of phase alignment, based on equation (3) (S17). The CPU 21 calculates the correction amount Δω of the phase of the tool axis 8 based on equation (4) (S19). The CPU 21 calculates the correction speed before applying the filter based on the correction amount Δω of the phase of the tool axis 8, and generates the correction speed of the tool axis 8 by using a moving average filter with time constants t1 and t2. The CPU 21 corrects the rotational speed of the tool axis 8 according to the generated correction speed (S21).

[0063] Based on the detection result of the encoder 54A, the CPU 21 determines whether the phase of the tool axis 8 has reached the specified phase β1 (S23). If the phase of the tool axis 8 has not reached the specified phase β1 (S23: NO), the CPU 21 returns the process to S21 and corrects the rotational speed of the tool axis 8 according to the correction speed generated in S19. When the phase of the tool axis 8 has reached the specified phase β1 (S23: YES), the CPU 21 starts the operation of the feed axis (S25). The tool axis 8 starts to move in the cutting direction. The CPU 21 ends the phase alignment control process and returns to the main process, and starts machining the work W with the tool D.

[0064] In addition, when ending the two-axis synchronous machining mode, the CPU 21 notifies that it is not in the mode in which two-axis synchronous machining is performed by displaying only the rotational speed (main spindle rotational speed) of the tool axis 8 in the main spindle rotational speed display area 125 (FIG. 12, S3).

[0065] As described above, the numerical control device 20 controls the synchronous rotation of the tool axis 8 and the workpiece axis 82 to machine the workpiece W. When phasing the tool axis 8 and the workpiece axis 82, the numerical control device 20 can set designated phases β1 and α1, which are the rotational phase angles of the tool axis 8 and the workpiece axis 82 when the phase alignment is completed. Therefore, the numerical control device 20 can control the tip B of the tool D that comes into contact with the workpiece W when machining of the workpiece W by the tool D is started, and can suppress wear of the tip B of the tool D.

[0066] The numerical control device 20 starts driving the X-axis, Y-axis, and Z-axis when phase alignment is complete, so that the timing at which the tool D comes into contact with the workpiece W can be kept constant for each machining operation.

[0067] In the numerical control device 20, the designated phase β1 and the designated phase α1 are specified as variables in the "G333" command, so the user does not need to perform an operation to set the designated phase β1 and the designated phase α1 in advance before executing the phase alignment operation.

[0068] The torque required to rotate the tool axis 8 is smaller than that required to rotate the workpiece axis 82. Therefore, the numerical control device 20 can smoothly align the phases of the tool axis 8 and the workpiece axis 82 by correcting the phase of the tool axis 8 to the specified phase β1.

[0069] The numerical control device 20 can notify the user that the tool axis 8 and the workpiece axis 82 are rotating synchronously by means of the spindle rotation speed display area 125 on the display screen 120 displayed on the display unit 29.

[0070] Since the workpiece W is a machined gear, the numerical control device 20 can machine the machined gear by synchronously rotating the tool shaft 8, which is a gear cutting tool, and the workpiece shaft 82.

[0071] In the above description, the jig is an example of the "base" of the present invention. The CPU 21 that performs two-axis synchronous control is an example of the "synchronous control unit" of the present invention. The CPU 21 that performs phase matching control is an example of the "phase control unit" of the present invention. The specified phase β1 is an example of the "set tool angle" of the present invention. The CPU 21 that executes the "G333 E_" command is an example of the "tool axis phase angle setting unit" of the present invention. The specified phase α1 is an example of the "set tool angle" of the present invention. The CPU 21 that executes the "G333 Q_" command is an example of the "work axis phase angle setting unit" of the present invention. The X-axis, Y-axis, and Z-axis are examples of the "feed axis" of the present invention. The CPU 21 that executes the process of S25 is an example of the "feed control unit" of the present invention. The NC program 100 is an example of the "processing program" of the present invention. The "G333" command is an example of the "phase command" of the present invention. The parameter "E_" of the "G333" command is an example of the "tool setting angle designation variable" of the present invention. The parameter "Q_" of the "G333" command is an example of the "work setting angle designation variable" of the present invention.

[0072] The phase matching start phase α0 is an example of the "start work angle" of the present invention. The CPU 21 that executes the process of S11 is an example of the "start work angle calculation unit" of the present invention. The phase matching start phase β0 is an example of the "start tool angle" of the present invention. The CPU 21 that executes the process of S15 is an example of the "start tool angle calculation unit" of the present invention. The phase β2 without correction is an example of the "end tool angle" of the present invention. The CPU 21 that executes the process of S17 is an example of the "end tool angle calculation unit" of the present invention. The CPU 21 that executes the process of S19 is an example of the "correction amount calculation unit" of the present invention. The CPU 21 that executes the process of S21 is an example of the "tool speed control unit" of the present invention. The display unit 29 is an example of the "display device" of the present invention. The spindle speed display area 125 is an example of the "notification screen" of the present invention. The CPU 21 that executes the process of S1 is an example of the "notification unit" of the present invention.

[0073] The present invention is not limited to the above-described embodiments, and various modifications can be made. Although the numerical control device 20 executes the phase matching control process based on the commands described in the NC program 100, the phase matching control process may be executed according to the instructions input by the operator from the input unit 28. The numerical control device 20 performs the phase matching control by correcting the rotational speed of the tool axis 8 while maintaining the rotational speed of the work axis 82, but the rotational speed of the work axis 82 may be corrected while maintaining the rotational speed of the tool axis 8. Alternatively, the numerical control device 20 may perform the phase matching control by correcting the rotational speeds of the tool axis 8 and the work axis 82, respectively.

[0074] In the "M142" command, the ratio of the rotational speed of the tool axis 8 to the work axis 82 is specified, but the magnification of the rotational speed of the tool axis 8 to the work axis 82 may be specified. Alternatively, without performing the "M142" command, by specifying not only the rotational speed of the work axis 82 but also the rotational speed of the tool axis 8 in the "M303" or "M304" command, the rotational speeds of the tool axis 8 and the work axis 82 may be directly specified by numerical values rather than by ratio. A command combining the "M142" command, the "M303" or "M304" command, and the "G333" command may be created and executed by one command.

[0075] The numerical control device 20 sets the cutting direction in which the tool axis 8 moves relative to the work axis 82 as the X-axis direction, but any direction among the X-axis, Y-axis, and Z-axis may be set as the cutting direction as long as the tool D can machine the work W. Further, the work axis 82 may be moved in the X-axis direction relative to the tool axis 8.

[0076] The numerical control device 20 may be provided with a function of appropriately shifting the tip B of the tool D that first contacts the workpiece W. For example, add "I_" to the parameter of the "G333" command. "I_" is a parameter that specifies the number of cutting edges of the tip B of the tool D. When the command interpreted by the CPU 21 is the "G333" command, as shown in FIG. 13, the CPU 21 executes the processes of S31 to S47 before executing S11 of the phase alignment process. In the processes of S31 to S47, the number of hold times is the number of times to hold the shift of the tip B of the tool D, and the initial value is 0. The shift phase H is the phase obtained by shifting the specified phase β1. In the processes of S11 to S25, the shift phase H is used in the calculation instead of the specified phase β1. Hst is the phase of the tool axis 8 in the reference machining (for example, the first machining in the machining repeated under the same conditions), that is, the specified phase β1. N is the number of cutting edges to be shifted, and the initial value is 0. The number of hold times and N are stored in the storage device.

[0077] The CPU 21 adds 1 to the number of hold times and stores it in the storage device 24 (S31). The CPU 21 uses the following formula (5): H = Hst + N × (360 / I) ···(5) Calculate the shift phase H for shifting the specified phase β1 (S33). That is, the shift phase H of the tool axis 8 is obtained by adding the value obtained by multiplying the installation angle interval (360 / I) of the tip B by the number of cutting edges N to be shifted to the reference Hst. Since the initial value of N is 0, the tip B that first contacts the workpiece W does not shift.

[0078] When the number of holds is less than 5 (S35: NO), the CPU 21 shifts the process to S11. Therefore, up to the first to fourth processing, the same chip B is set as the chip B that first contacts the workpiece W. When the number of holds reaches 5 or more (S35: YES), the CPU 21 resets the number of holds to 0 (S37), adds 1 to N, and stores it in the storage device 24 (S39). From the next time on, the shift phase H becomes the phase where chip B is shifted by one chip. When N is less than I (S41: NO), the CPU 21 shifts the process to S11. When N is I or more (S41: YES), the CPU 21 sets N to 0 and stores it in the storage device 24 (S43). As a result, when all chip Bs are used as the chip B that first contacts the workpiece W, the chip B used in the earliest stage is set as the chip B that first contacts the workpiece W. The process shifts to S11.

[0079] Each time the workpiece W is processed multiple times by the tool D, the numerical control device 20 can sequentially shift the chip B that first hits the workpiece W during processing by changing the shift phase H, thereby suppressing the wear of the tool D. Note that the chip B is an example of the "blade" of the present invention. The CPU 21 that executes the process of S33 is an example of the "tool angle shift unit" of the present invention. In this modification, the number of holds determined in S35 is not limited to 5 or more, and the number may be set as appropriate. Alternatively, the number of holds may not be set. Also, in S39, the number added to N is not limited to +1, and it may be set to shift by one skip, such as +2.

Explanation of Signs

[0080] 1 Machine tool 8 Tool axis 20 Numerical control device 21 CPU 29 Display unit 82 Workpiece axis 100 NC program 125 Main shaft rotation speed display area D Tool F Phase alignment time W Workpiece Δω Correction amount α0, β0 phase alignment start phase α1, β1 specified phase β2 non-corrected phase B chip

Claims

1. In a numerical control device that performs machining of the workpiece by controlling a machine tool including a tool shaft for mounting a tool and a workpiece shaft for rotating a table for fixing the workpiece, a synchronization control unit that performs control to rotate the tool shaft and the workpiece shaft synchronously; a phase control unit that aligns the rotation phase angles of the tool shaft and the workpiece shaft based on the rotation phase angle of the tool shaft and the rotation phase angle of the workpiece shaft during the synchronous rotation of the tool shaft and the workpiece shaft by the synchronization control unit is provided, wherein the phase control unit includes a tool shaft phase angle setting unit that sets a set tool angle, which is the rotation phase angle of the tool shaft when the phase alignment ends; and a workpiece shaft phase angle setting unit that sets a set workpiece angle, which is the rotation phase angle of the workpiece shaft when the phase alignment ends ; the relative rotation speeds of the tool shaft and the workpiece shaft are controlled so that the rotation phase angle of the tool shaft becomes the set tool angle and the rotation phase angle of the workpiece shaft becomes the set workpiece angle when the phase alignment between the tool shaft and the workpiece shaft ends, thereby performing the phase alignment characterizes the numerical control device.

2. The machine tool includes a feed shaft that relatively moves the tool shaft and the workpiece shaft, wherein the phase control unit includes a feed control unit that controls the drive of the feed shaft, and the feed control unit drives the feed shaft when the rotation phase angle of the tool shaft becomes the set tool angle and the rotation phase angle of the workpiece shaft becomes the set workpiece angle, and starts the relative movement between the tool shaft and the workpiece shaft toward the position where the tool machines the workpiece characterizes the numerical control device according to Claim 1.

3. The numerical control device starts the phase alignment operation according to a phase command that instructs the phase alignment operation between the tool shaft and the workpiece shaft, the tool shaft phase angle setting unit sets the set tool angle based on a tool setting angle designation variable that designates the set tool angle in the phase command, and the workpiece shaft phase angle setting unit sets the set workpiece angle based on a workpiece setting angle designation variable that designates the set workpiece angle in the phase command characterizes the numerical control device according to Claim 1.

4. The phase control unit Based on the set work angle, the work axis synchronization speed which is the rotational speed of the work axis during machining controlled by the synchronization control unit, and the phase alignment time which is the time required for phase alignment and is set in advance, an initial work angle calculation unit that calculates the initial work angle which is the rotational phase angle of the work axis at the start of the phase alignment An initial tool angle calculation unit that calculates the initial tool angle which is the rotational phase angle of the tool axis when the work axis reaches the initial work angle Based on the initial tool angle, the tool axis synchronization speed which is the rotational speed of the tool axis during machining controlled by the synchronization control unit, and the phase alignment time, a final tool angle calculation unit that calculates the final tool angle which is the rotational phase angle that the tool axis reaches after the elapse of the phase alignment time from the initial tool angle A correction amount calculation unit that calculates the difference between the set tool angle and the final tool angle as the correction amount A tool speed control unit that controls the rotational speed of the tool axis based on the correction amount so that the tool axis reaches the set tool angle after the elapse of the phase alignment time from the initial tool angle including The numerical control device according to claim 1, characterized in that

5. The machine tool is provided with a display device for displaying information, The synchronization control unit includes a notification unit that causes the display device to display a notification screen for notifying that the tool axis and the work axis are rotating in synchronization The numerical control device according to claim 1, characterized in that

6. The phase control unit includes a tool angle shift unit that changes the set tool angle based on the number of cutting edges of the tool, The tool angle shift unit changes the set tool angle every time one or more machining operations of the work by the tool are performed The numerical control device according to claim 1, characterized in that

7. The work is a machining gear The numerical control device according to claim 1, characterized in that

8. A control method for a numerical control device that performs machining of a work by controlling a machine tool having a tool axis for mounting a tool and a work axis for rotating a table for fixing the work, comprising: a synchronization control step of performing control to synchronously rotate the tool axis and the work axis; a phase control step of performing phase alignment of the rotational phase angles of the tool axis and the work axis based on the rotational phase angle of the tool axis and the rotational phase angle of the work axis during the synchronous rotation of the tool axis and the work axis by the synchronization control step comprising The phase control step is A tool axis phase angle setting step of setting a set tool angle which is the rotational phase angle of the tool axis when the phase alignment ends; A work axis phase angle setting step of setting a set work angle which is the rotational phase angle of the work axis when the phase alignment ends; including; Performing the phase alignment by relatively controlling the rotational speed of the tool axis and the rotational speed of the work axis so that the rotational phase angle of the tool axis when the phase alignment of the tool axis and the work axis ends becomes the set tool angle, and the rotational phase angle of the work axis becomes the set work angle. A control method characterized by the above.

9. A program for causing a numerical control device that performs machining of the work by controlling a machine tool including a tool axis for mounting a tool and a work axis for rotating a table for fixing the work to function, causing a computer to, perform a synchronization control step of performing control to rotate the tool axis and the work axis synchronously; During the synchronous rotation of the tool axis and the work axis by the synchronization control step, perform a phase control step of aligning the rotational phase angles of the tool axis and the work axis based on the rotational phase angle of the tool axis and the rotational phase angle of the work axis. causing it to execute; In the phase control step, perform a tool axis phase angle setting step of setting a set tool angle which is the rotational phase angle of the tool axis when the phase alignment ends; perform a work axis phase angle setting step of setting a set work angle which is the rotational phase angle of the work axis when the phase alignment ends; causing it to execute; Performing the phase alignment by relatively controlling the rotational speed of the tool axis and the rotational speed of the work axis so that the rotational phase angle of the tool axis when the phase alignment of the tool axis and the work axis ends becomes the set tool angle, and the rotational phase angle of the work axis becomes the set work angle. A program characterized by the above.

10. A program for causing a numerical control device that performs machining of the work by controlling a machine tool including a tool axis for mounting a tool and a work axis for rotating a table for fixing the work to function, causing a computer to, perform a synchronization control step of performing control to rotate the tool axis and the work axis synchronously; During the synchronous rotation of the tool axis and the work axis by the synchronization control step, perform a phase control step of aligning the rotational phase angles of the tool axis and the work axis based on the rotational phase angle of the tool axis and the rotational phase angle of the work axis. causing it to execute; In the phase control step, a tool axis phase angle setting step of setting a set tool angle which is a rotational phase angle of the tool axis when the phase alignment ends, a work axis phase angle setting step of setting a set work angle which is a rotational phase angle of the work axis when the phase alignment ends are executed, and a program for performing the phase alignment by relatively controlling the rotational speed of the tool axis and the rotational speed of the work axis so that the rotational phase angle of the tool axis when the phase alignment of the tool axis and the work axis ends becomes the set tool angle and the rotational phase angle of the work axis becomes the set work angle is stored. A storage medium characterized by this.

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