阅读说明：本技术 数值控制装置、机床系统以及数值控制方法 (Numerical controller, machine tool system, and numerical control method ) 是由 山田贵之 于 2020-09-08 设计创作，主要内容包括：本发明提供数值控制装置、机床系统以及数值控制方法,可抑制因切削工具与工件的相对振动而产生的偏芯,提高精加工形状的精度,抑制对切削工具前端的影响。该数值控制装置使机床进行通过使切削工具与加工对象相对地移动而对加工对象进行多次切入加工而在加工对象上形成螺纹的螺纹切削加工的动作,具备：控制使加工对象旋转的主轴和3轴的驱动轴的驱动部；为使切削工具与加工对象沿着螺纹槽相对地振动,而使对3轴中的2轴以上施加的振动叠加在切削工具与加工对象的相对移动上的振动叠加部和多次切入加工中,使振动的相位相对于主轴的相位每次错开预先决定的振动相位偏移量的螺纹切削振动调整部。(The invention provides a numerical controller, a machine tool system, and a numerical control method, which can suppress the occurrence of core displacement due to relative vibration between a cutting tool and a workpiece, improve the precision of a finished shape, and suppress the influence on the tip of the cutting tool. The numerical controller causes a machine tool to perform a thread cutting operation of performing a plurality of cutting operations on a workpiece by moving a cutting tool relative to the workpiece to form a thread on the workpiece, the numerical controller including: a drive unit for controlling a main shaft for rotating the processing object and a 3-shaft drive shaft; and a thread cutting vibration adjustment unit for shifting the phase of vibration relative to the phase of the main shaft by a predetermined vibration phase shift amount each time, in a vibration superposition unit for superposing vibration applied to 2 or more of the 3 axes on the relative movement between the cutting tool and the object, and in a multiple cutting operation, in order to vibrate the cutting tool and the object along the thread groove.)

1. A numerical controller for causing a machine tool to perform a thread cutting operation for forming a thread on a work object by relatively moving a cutting tool and the work object and performing a plurality of cutting operations on the work object,

the numerical controller includes:

a drive unit that controls a main shaft that rotates the processing object and a 3-axis drive shaft;

a vibration superimposing unit that superimposes vibrations applied to 2 or more of the 3 axes on relative movement between the cutting tool and the object to be machined so as to cause the cutting tool and the object to be machined to vibrate relative to each other along the thread groove; and

and a thread cutting vibration adjusting unit that shifts the phase of the vibration relative to the phase of the main shaft by a predetermined vibration phase shift amount each time during the plurality of times of the cutting.

2. The numerical control apparatus according to claim 1,

the vibration superimposing unit is configured to change a frequency of the vibration.

3. Numerical control apparatus according to claim 1 or 2,

the vibration superimposing unit is configured to set the amplitude of the vibration in accordance with the cutting depth of each cutting process.

4. Numerical control apparatus according to any one of claims 1 to 3,

the vibration superimposing section vibrates 2 of the 3 axes.

5. The numerical control apparatus according to any one of claims 1 to 4,

the vibration superimposing unit vibrates the 3 axes, and an angle formed between 2 of the 3 axes is 0 ° or more and 90 ° or less.

6. A machine tool system is characterized by comprising:

the numerical control apparatus according to any one of claims 1 to 5; and

and a machine tool that moves a cutting tool relative to a workpiece to perform multiple plunge cutting on the workpiece, thereby forming a thread on the workpiece.

7. A numerical control method of a numerical control apparatus for performing a thread cutting operation of moving a cutting tool and a workpiece relative to each other to perform a plurality of plunge cuts into the workpiece to form a thread on the workpiece, the numerical control method comprising the steps of,

a main shaft for rotating the processing object and a driving shaft of 3 shafts are controlled,

superimposing vibrations applied to 2 or more of the 3 axes on the relative movement between the cutting tool and the object to be machined in order to cause the cutting tool and the object to be machined to vibrate relative to each other along the thread groove,

in the multiple cutting, the phase of the vibration is shifted from the phase of the spindle by a predetermined vibration phase shift amount.

Technical Field

The present invention relates to a numerical controller, a machine tool system, and a numerical control method, and more particularly to a numerical controller, a machine tool system, and a numerical control method for performing a screw cutting process while cutting chips into pieces by a machine tool

Background

For example, patent document 1 describes a numerical controller for a machine tool that performs a screw cutting process while cutting chips.

The control device for a machine tool described in patent document 1 prevents chips that are connected in a long length from being caught on a workpiece or a cutting tool and from damaging a machined surface of the workpiece when the workpiece is subjected to thread cutting.

Specifically, the control device for a machine tool described in patent document 1 includes a vibration setting unit configured to: the thread cutting is performed by relatively rotating a workpiece and a cutting tool and relatively performing feed movement in a machining feed direction, and relatively vibrating the workpiece and the cutting tool in a radial direction of the workpiece to perform a plurality of times of spiral cutting.

Patent document 1: international publication No. 2016/056526 pamphlet.

Disclosure of Invention

Problems to be solved by the invention

In thread cutting of a workpiece in a machine tool, it is desirable to suppress as much as possible the influence of relative vibration between a cutting tool and the workpiece on the rotating workpiece in order to improve the machining accuracy. In this regard, the control device described in patent document 1 is only the vibration of the uniaxial cutting tool in the radial direction of the workpiece, and thus there is a possibility that the workpiece being rotated is eccentric. Therefore, it is desired to suppress the occurrence of misalignment due to relative vibration between the cutting tool and the workpiece, to improve the accuracy of the finished shape, and to suppress the influence on the cutting tool tip (tip).

Means for solving the problems

(1) A 1 st aspect of the present disclosure is a numerical controller that causes a machine tool to perform a thread cutting operation of forming a thread on a work object by moving a cutting tool relative to the work object to perform a plurality of cutting operations on the work object, the numerical controller including:

a drive unit that controls a main shaft that rotates the processing object and a 3-axis drive shaft;

a vibration superimposing unit that superimposes vibrations applied to 2 or more of the 3 axes on relative movement between the cutting tool and the object to be machined so as to cause the cutting tool and the object to be machined to vibrate relative to each other along a thread groove; and

and a thread cutting vibration adjusting unit that shifts the phase of the vibration relative to the phase of the main shaft by a predetermined vibration phase shift amount each time during the plurality of times of the cutting.

(2) A 2 nd aspect of the present disclosure is a machine tool system including:

the numerical controller according to (1) above; and

and a machine tool that moves a cutting tool relative to a workpiece to perform multiple plunge cutting operations on the workpiece, thereby forming a thread on the workpiece.

(3) A 3 rd aspect of the present disclosure is a numerical control method of a numerical controller for performing a thread cutting operation of moving a cutting tool relative to a workpiece to perform a plurality of cutting operations on the workpiece to form a thread on the workpiece,

in the numerical control method,

a main shaft for rotating the processing object and a driving shaft of 3 shafts are controlled,

in order to vibrate the cutting tool and the object along the thread groove, vibration applied to 2 or more of the 3 axes is superimposed on the relative movement between the cutting tool and the object, and the phase of the vibration is shifted from the phase of the main spindle by a predetermined vibration phase shift amount each time in the cutting process a plurality of times.

Effects of the invention

According to the aspects of the present disclosure, in the thread cutting process of the machine tool on the processing object, by applying vibration to 2 or more axes of the X axis, the Y axis, and the Z axis, it is possible to suppress the occurrence of misalignment due to relative vibration between the cutting tool and the processing object, improve the accuracy of the finished shape, and suppress the influence on the tip of the cutting tool.

Drawings

Fig. 1 is a block diagram showing a machine tool system according to an embodiment of the present disclosure.

Fig. 2 is a plan view showing the vibration direction of the cutting tool in the thread groove direction of the workpiece when the workpiece is viewed from the cutting tool.

Fig. 3 is a partial cross-sectional view showing a vibration direction of the cutting tool with respect to the workpiece as viewed from the distal end side of the workpiece.

Fig. 4 is a conceptual diagram showing the trajectory of the cutting tool in 1 thread groove of the workpiece as viewed in the Z-axis direction after the 1 st and 2 nd cutting processes.

Fig. 5 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 1 st plunge cutting process.

Fig. 6 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 1 st plunge cutting process.

Fig. 7 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 1 st plunge cutting process.

Fig. 8 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 1 st plunge cutting process.

Fig. 9 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 1 st plunge cutting process.

Fig. 10 is a conceptual diagram illustrating rotation of a workpiece on which cutting is not performed, among the workpieces viewed in the Z-axis direction in the 2 nd cutting process.

Fig. 11 is a conceptual diagram illustrating rotation of a workpiece on which cutting is not performed, among the workpieces viewed in the Z-axis direction in the 2 nd cutting process.

Fig. 12 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 2 nd cut machining.

Fig. 13 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 2 nd cut machining.

Fig. 14 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 2 nd cut machining.

Fig. 15 is a conceptual diagram illustrating a trajectory of the cutting tool in the thread groove of the workpiece as viewed from the Z-axis direction in the 2 nd cut machining.

Fig. 16 is a conceptual diagram illustrating a trajectory of the cutting tool in 1 thread groove of the workpiece as viewed from the Z-axis direction in the 1 st and 2 nd cutting processes.

Fig. 17 is a conceptual diagram illustrating the trajectory of one thread groove after the first and second cutting processes when the cutting angle θ is 90 °.

Fig. 18 is a conceptual diagram illustrating the trajectory of one thread groove after the first and second cutting processes when the cutting angle θ is 80 °.

Fig. 19 is a conceptual diagram illustrating the trajectory of one thread groove after the first and second cutting processes when the cutting angle θ is 45 °.

Fig. 20 is a conceptual diagram illustrating the trajectory of one thread groove after the first and second cutting processes when the cutting angle θ is 0 °.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

Fig. 1 is a block diagram showing a machine tool system according to an embodiment of the present disclosure.

As shown in fig. 1, machine tool system 10 includes a machine tool 100 and a numerical controller 200. Further, the numerical controller 200 may be included in the machine tool 100.

First, the machine tool 100 will be explained.

As shown in fig. 1, a machine tool 100 includes a linear servo motor 101, a headstock 102, a spindle motor 103, and a workpiece 104. The spindle motor 103 rotates a workpiece 104 to be machined attached to a rotating shaft via a chuck, not shown. Further, the linear servo motor 101 moves a headstock 102 to which a spindle motor 103 is attached in a feeding direction of the Z axis shown in fig. 1, and moves a workpiece 104 in the feeding direction. Further, the linear servo motor 101 reciprocates the workpiece 104 in the Z-axis direction in superimposition with the movement of the workpiece 104 in the feeding direction. The cutting tool 110 performs cutting from the tip of the rotating workpiece 104 by moving the workpiece 104 in the feed direction, and forms a thread. The thread is formed by performing a plurality of cutting processes.

The machine tool 100 includes a linear servo motor 105, a support table 106, a support column 107, a linear servo motor 108, a tool table 109, and a cutting tool 110. The linear servo motor 105 reciprocates the support base 106 in the Y axis direction, not shown. The cutting tool 110 is a turning tool or the like that performs cutting into the rotating workpiece 104. The support base 106 is provided with a support column 107. The linear servo motor 108 is attached to a side surface of the support column 107, and reciprocates a tool table 109 to which a cutting tool 110 is attached in the X-axis direction.

The reciprocating movement in the X-axis direction, the reciprocating movement in the Y-axis direction, and the reciprocating movement in the Z-axis direction correspond to the vibration in the X-axis direction, the vibration in the Y-axis direction, and the vibration in the Z-axis direction, respectively. Hereinafter, the reciprocating movement is referred to as vibration.

The workpiece 104 is rotated by the spindle motor 103 and moved in the Z-axis feeding direction by the linear servo motor 101. Further, the workpiece 104 is vibrated in the Z-axis direction by the linear servo motor 101, and as a result, the cutting tool 110 is vibrated relative to the workpiece 104 in the Z-axis direction. The cutting tool 110 is vibrated in the Y-axis direction by the linear servo motor 105, and vibrated in the X-axis direction by the linear servo motor 108. The cutting tool 110 performs the thread cutting process on the workpiece 104 by cooperating the Z-axis movement and the Z-axis vibration of the rotating workpiece 104 with the X-axis vibration and the Y-axis vibration of the cutting tool 110. In the following description, the linear servomotor 101 vibrates the workpiece 104 in the Z-axis direction, and the cutting tool 110 is vibrated in the Z-axis direction with respect to the workpiece 104 as vibration of the cutting tool 110 in the Z-axis direction.

The X-axis direction, Y-axis direction, and Z-axis direction vibrations of the cutting tool 110 are shown in fig. 2 and 3.

Fig. 2 is a plan view showing the vibration direction of the cutting tool 110 in the thread groove direction of the workpiece 104 when the workpiece 104 is viewed from the cutting tool 110 side. The cutting tool 110 is not shown in fig. 2. Fig. 3 is a partial cross-sectional view showing the direction of vibration of the cutting tool 110 with respect to the workpiece 104, as viewed from the leading end side of the workpiece 104. The direction of travel of the tool shown in fig. 2 indicates the direction in which the cutting tool 110 is moved relative to the workpiece 104 by moving the workpiece 104 in the Z-axis feed direction by the linear servomotor 101. In fig. 3 and 4, the cutting tool 110 is represented by a triangle for simplicity.

As shown in fig. 2, the cutting tool 110 vibrates in the Y-axis direction and the Z-axis direction, which are the same as the thread groove direction. As shown in fig. 3, the cutting tool 110 vibrates in the X-axis direction in addition to the vibrations in the Y-axis direction and the Z-axis direction shown in fig. 2. As shown in fig. 3, the chips are cut at a portion where the tip of the cutting tool 110 reaches the outer peripheral surface of the workpiece 104.

Fig. 4 is a conceptual diagram showing a trajectory of the cutting tool in one thread groove of the workpiece as viewed from the Z-axis direction after the first and second cutting processes. Fig. 4 shows the shape of the 1 st and 2 nd cutting operations, but in reality the cutting operations are repeated as in the 1 st and 2 nd cutting operations until the diameter of the trajectory of the 1 st thread groove is set to a circle. The auxiliary circle in fig. 4 indicates the circumference of the workpiece 104 and the maximum machining depth machined in the first plunge machining. The number of times of the plunge cutting is set by performing the thread cutting process by performing the plunge cutting process several times.

The cutting tool 110 machines the workpiece 104 to form a shape of the first and second plunge cuts shown in fig. 4.

Instead of the linear servo motor 101, the linear servo motor 108, and the linear servo motor 105, a motor that moves the workpiece 104 in the Z-axis feeding direction and vibrates the workpiece in the Z-axis direction and a motor that vibrates the cutting tool 110 in the X-axis and Y-axis directions may be used.

Next, the numerical controller 200 will be explained.

As shown in fig. 1, the numerical controller 200 includes an analysis processing unit 201, an interpolation processing unit 202, an acceleration/deceleration processing unit 203, a control command output unit 204, and a driving unit 205. The interpolation processing unit 202 includes a vibration superimposing unit 2021 and a vibration adjusting unit 2022.

The analysis processing unit 201 analyzes a machining program including one or more blocks for each block, reads a movement path and a feed speed, generates a movement command, and outputs the movement command to the interpolation processing unit 202. The analysis processing unit 201 reads a vibration command from the machining program, generates a vibration condition, and outputs the vibration condition to the interpolation processing unit 202.

In the interpolation processing unit 202, the vibration superimposing unit 2021 calculates a command movement amount to be moved at a feed speed specified during a processing cycle which is a control cycle of the numerical controller 200, using the movement command, calculates a vibration movement amount during the processing cycle for vibrating the cutting tool 110 and the workpiece 104 using the vibration command, and further calculates a superimposed movement amount by which the vibration movement amount and the command movement amount are superimposed. Specifically, the vibration superimposing unit 2021 calculates the amount of overlap movement so that 2 or 3 of the X, Y, and Z axes out of the 3 drive axes, i.e., the X, Y, and Z axes, are superimposed on the relative movement of the cutting tool 110 and the workpiece 104.

By vibrating 2 axes of the X axis and the Z axis, or 3 axes of the X axis, the Y axis, and the Z axis, it is possible to suppress the misalignment caused by the relative vibration between the cutting tool and the workpiece, improve the precision of the finished shape, and suppress the influence on the tip of the cutting tool. For example, as shown in fig. 1, in the case where the vibration is only the vibration of the X axis in the radial direction of the workpiece 104, a force is applied in parallel with the radial direction of the workpiece. However, if the X, Y, or Z axis, or the X, Y, and Z axes are vibrated and vibrated in the thread groove direction shown in fig. 2, the force in the radial direction of the workpiece can be dispersed, and misalignment can be suppressed.

The vibration adjusting unit 2022 shifts the phase of the vibration with respect to the phase of the main shaft by a predetermined vibration phase shift amount each time in the multiple cutting processes. For example, the vibration adjusting unit 2022 sets the phase of the vibration in the 2 nd cutting process to an opposite relationship to the phase of the vibration in the 1 st cutting process, and vibrates the cutting process so that the cutting process starts from the start of the operation for returning the vibration (predetermined lower) in the 1 st cutting process and starts from the start of the operation for going to the vibration (predetermined lower) in the 2 nd cutting process. Here, the returning operation of the vibration refers to an operation in which the tip of the cutting tool 110 is directed toward the outer peripheral surface of the workpiece 104, and the forward operation of the vibration refers to an operation in which the tip of the cutting tool 110 is separated from the outer peripheral surface of the workpiece 104. The action of the vibration adjusting unit 2022 will be described in detail later.

The acceleration/deceleration processing unit 203 converts the amount of overlap movement of each drive axis, which is output from the interpolation processing unit 202 and in which the amount of vibration phase shift is adjusted, into a movement command for each processing cycle in consideration of acceleration/deceleration, in accordance with a pre-specified acceleration/deceleration pattern.

The control command output unit 204 outputs the movement command output from the acceleration/deceleration processing unit 203 to the driving unit 205 as a control command.

The drive unit 205 controls 3 axes, i.e., a main axis for rotating the workpiece 104, a Z axis for moving and oscillating the workpiece 104, and an X axis and a Y axis for oscillating the cutting tool 110, in accordance with a control command. The drive unit 205 includes a spindle control unit that controls the spindle motor 103 that rotates the workpiece 104, and a Z-axis servo control unit that controls the linear servo motor 101 that moves and vibrates the workpiece 104 in the Z-axis feeding direction. The driving unit 205 includes an X-axis servo control unit that controls the linear servo motor 108 that vibrates the cutting tool 110 in the X-axis direction, and a Y-axis servo control unit that controls the linear servo motor 105 that vibrates the cutting tool 110 in the Y-axis direction. These control units are already known, and therefore, illustration and explanation thereof are omitted.

The functional blocks included in the numerical controller 200 are explained above.

To realize these functional blocks, the numerical controller 200 includes an arithmetic Processing Unit such as a CPU (Central Processing Unit). The numerical controller 200 further includes a secondary storage device such as a Hard Disk Drive (HDD) that stores various control programs such as application software and an Operating System (OS), and a main storage device such as a Random Access Memory (RAM) that stores data temporarily required for the execution of the programs by the arithmetic processing unit.

In the numerical controller 100, the arithmetic processing unit reads the application software and the OS from the auxiliary storage device, and performs arithmetic processing based on the read application software and the OS while expanding the application software and the OS in the main storage device. Various hardware provided in each device is controlled based on the calculation result. Thereby realizing the functional blocks of the present embodiment. That is, the present embodiment can be realized by cooperation of hardware and software.

When the amount of computation of the numerical controller 200 is large, it is preferable to mount a GPU (Graphics Processing Units) on a personal computer, for example, and use the GPU for computation Processing because high-speed Processing is possible by a technique called GPGPU (UT-Graphics Processing Units). Further, in order to perform higher-speed processing, a computer cluster is constructed using a plurality of computers on which such GPUs are mounted, and parallel processing is performed by a plurality of computers included in the computer cluster.

Next, the operation of the 1 st and 2 nd cutting operations will be described with reference to fig. 5 to 16. In fig. 5 to 16, the cutting tool 110 is shown in a triangular shape for simplicity.

Fig. 5 to 9 are conceptual views each showing a trajectory of the thread groove of the cutting tool on the workpiece as viewed in the Z-axis direction in the first cutting process. In fig. 5 to 9, only the vibrations of the cutting tool in the X-axis direction and the Y-axis direction are shown, but the vibrations in the Z-axis direction are also shown in fig. 2. In the following operation, the cutting tool 110 reaches a portion of the outer peripheral surface during the return operation, and the chips are cut.

In the 1 st plunge cutting, as shown in fig. 5, the cutting tool 110 is vibrated so as to start the plunge cutting from the start of the return motion of the vibration, and the tip of the cutting tool 110 reaches the outer peripheral surface of the workpiece 104 at the time of the return motion of the cutting tool 110. The workpiece 104 is plunged from the leading end by the cutting tool 110.

Next, as shown in fig. 6, after the forward movement of the cutting tool 110, the return movement of the cutting tool 110 is performed as shown in fig. 7.

Further, as shown in fig. 8, the cutting tool 110 is moved forward. In this way, the trajectory of the cutting tool in one thread groove shown in fig. 9 is obtained.

Fig. 5 to 9 show the trajectory of the cutting tool in one thread groove during one rotation of the workpiece 104, but the number of rotations of the workpiece 104 is determined by the length of the portion where the thread groove is formed. Therefore, in the first cutting process, the workpiece 104 is rotated by a predetermined number of revolutions, and the thread groove is formed in a spiral shape.

Next, in the 2 nd plunge cutting, the phase of the vibration is shifted from the phase of the spindle by a predetermined vibration phase shift amount. In the present embodiment, specifically, the vibration adjusting unit 2022 sets the phase of the vibration in the 2 nd cutting process to a relationship opposite to the phase of the vibration in the 1 st cutting process, and vibrates so that the cutting process is started from the start of the return operation of the vibration in the 1 st cutting process and the cutting process is started from the start of the forward operation of the vibration in the 2 nd cutting process. Then, the trajectory of the cutting tool 110 in the return operation in the 2 nd plunge cutting is set to the position of the trajectory of the cutting tool 110 in the return operation switched from the previous operation in the 1 st plunge cutting.

In the second cutting process, as shown in fig. 10, the workpiece 104 is rotated from the trajectory of the thread groove of fig. 9, and the workpiece 104 is rotated by half a cycle to the trajectory of the thread groove of fig. 11. The rotation operation without cutting is performed such that the phase at the time of cutting in the 2 nd cutting is changed from the phase at the time of cutting in the 1 st cutting, and the start position of the trajectory of the cutting tool 110 at the time of the forward operation in the 2 nd cutting reaches the predetermined position of the trajectory of the cutting tool 110 in the 1 st cutting.

Thereafter, as shown in fig. 12, the cutting tool 110 is vibrated so as to start the cutting process from the start of the movement before the vibration. In the following operation, the cutting chip is cut at a portion that reaches the outer peripheral surface when the cutting tool 110 performs the return operation.

Next, as shown in fig. 13, after the cutting tool 110 is returned, as shown in fig. 14, the cutting tool 110 is moved forward.

Then, as shown in fig. 15, the cutting tool 110 is returned. In this way, the trajectory of the cutting tool in one thread groove shown in fig. 16 is obtained. In the second cutting, as in the first cutting, the workpiece 104 is rotated by a predetermined number of revolutions, and the thread groove is formed in a spiral shape.

In the subsequent 3 rd plunge cutting, the workpiece 104 is rotated by half a revolution without performing plunge cutting, as in the 2 nd plunge cutting. The rotation operation without performing the cutting is performed to change the phase at the time of cutting in the 3 rd cutting with respect to the phase at the time of cutting in the 2 nd cutting so that the start position of the trajectory of the cutting tool 110 at the time of the forward operation in the 3 rd cutting reaches the predetermined position of the trajectory of the cutting tool 110 in the 2 nd cutting. The start position of the trajectory of the 3 rd cutting tool 110 is returned to the start position of the trajectory of the 1 st cutting tool 110 by the rotational operation without cutting in the 3 rd cutting. The vibration adjusting unit 2022 sets the phase of the vibration in the 3 rd cutting process to be in an opposite relationship to the phase of the vibration in the 2 nd cutting process.

Fig. 16 shows the shape of the 1 st and 2 nd cutting operations, but actually the cutting operations are performed until the trajectory of 1 thread groove becomes a circle having a set diameter. The number of times of the plunge cutting is set by performing the thread cutting process by performing the plunge cutting process several times.

< relationship between cutting Angle and cutting Path >

In the above description, the angle θ of the vibration direction of the Y axis of the cutting tool with respect to the X axis direction (hereinafter referred to as the cutting angle θ) was described as being fixed to be constant, but the cutting angle θ can be arbitrarily set in the range of 0 ° ≦ θ ≦ 90 °. Fig. 17 to 20 are conceptual diagrams showing the trajectory (cutting path) of one thread groove after the first and second cutting processes when the cutting angle θ is 90 °, 80 °, 45 °, and 0 °, respectively.

Although fig. 17 to 20 do not show the Z-axis vibration, the cutting tool actually vibrates relatively to the workpiece 104 in the Z-axis direction. When the cutting angle θ is 0 °, the vibration of the cutting tool in the Y-axis direction disappears, and the vibration becomes 2-axis vibration, which is vibration in the X-axis direction and the Z-axis direction.

As shown in fig. 17 to 20, the shape of the cutting path differs depending on the cutting angle θ. When the cutting angle θ is 0 °, the cutting path is elliptical as shown in fig. 20.

As the cutting angle θ is larger, the force acting in the radial direction of the workpiece 104 can be dispersed in a direction other than the radial direction of the workpiece, and the force acting in the radial direction of the workpiece 104 can be reduced. However, as shown in fig. 17 to 20, the larger the cutting angle θ, the more uneven the trajectory of the cutting tool becomes, and the variation in cutting load becomes uneven. Therefore, the cutting angle θ is adjusted according to the machining conditions of the thread cutting.

Each of the components included in the numerical controller 200 described above can be realized by hardware, software, or a combination thereof. The numerical control method performed by cooperation of each of the components included in the numerical controller 200 can be realized by hardware, software, or a combination thereof. Here, the implementation by software means an implementation in which a program is read and executed by a computer.

The program may be stored using various types of non-transitory computer readable media and provided to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (e.g., hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only memories), CD-R, CD-R/W, semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (erasable PROMs), flash ROMs, RAMs (random access memories)).

The above-described embodiment is an embodiment suitable for the present invention, but the scope of the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention.

For example, in the above embodiment, the trajectory of the cutting tool 110 in the return operation in the 2 nd plunge cutting reaches the position of the trajectory of the cutting tool 110 in the 1 st plunge cutting switched from the forward operation to the return operation, but the trajectory of the cutting tool 110 in the return operation in the 2 nd plunge cutting may exceed the position of the trajectory of the cutting tool 110 in the 1 st plunge cutting switched from the forward operation to the return operation.

In the above-described embodiment, the case where the number of vibrations of the cutting tool 110 is fixed in the first and second cutting operations, and the cutting tool 110 vibrates in the X-axis direction at a rate of 2 times in rotation with respect to the workpiece 1 has been described as an example.

However, the frequency of the vibration may be changed in the first and second cutting processes.

For example, in the 1 st plunge cutting, the cutting tool 110 may oscillate at a rate of 1 rotation with respect to the spindle 8, and in the 2 nd plunge cutting, the cutting tool 110 may oscillate at a rate of 1 rotation with respect to the spindle 4. Similarly to the 3 rd and subsequent times, the frequency of the vibration may be increased according to the number of times of the cutting.

As a result, the frequency gradually increases as the number of times increases, and the irregularities of the thread bottom surface of the workpiece 104 by the thread cutting process become thin.

In the above-described embodiment, the amplitude of the vibration is equal to the cutting depth in the cutting process, and thus the cutting portions in two consecutive cutting processes are in contact with each other.

However, the amplitude of the vibration can be set by, for example, a ratio (amplitude cut ratio) to an actual cut amount of the cutting tool with respect to the workpiece, or the amplitude may be set to be larger than the cut amount.

For example, by setting the amplitude cutting ratio to be larger than 1, the amplitude can be set to be larger than the cutting depth, and the trajectory of the cutting tool 110 in the returning operation in the 2 nd cutting operation can be made to exceed the position of the trajectory of the cutting tool 110 in the switching operation from the forward operation to the returning operation in the 1 st cutting operation.

In the above embodiment, the cutting depth in each cutting process is set to be the same, but the cutting depth may be controlled to be smaller as the number of cutting processes increases. As a result, the irregularities on the bottom surface of the thread of the workpiece 104 gradually decrease as the number of times of the cutting process increases. The amplitude of the vibration during the cutting can be set according to the cutting depth, and the vibration can be controlled to be smaller as the number of times of the cutting is increased.

In the above-described embodiment, the cutting tool 110 performs the thread cutting process on the workpiece 104 by cooperating the movement and vibration in the Z-axis feed direction of the rotating workpiece 104 with the vibration in the X-axis direction and the Y-axis direction of the cutting tool 110.

However, the vibration in the X-axis direction and the Y-axis direction may be applied to the workpiece 104, or the cutting tool 110 may be moved in a direction opposite to the feeding direction shown in fig. 1, instead of moving the workpiece 104 in the feeding direction. Instead of vibrating the workpiece 104 in the Z-axis direction, a motor such as a linear motor that vibrates the cutting tool 110 may be provided to vibrate the cutting tool 110 in the Z-axis direction.

The numerical controller, the machine tool system, and the numerical control method according to the present disclosure include the above-described embodiments, and various embodiments having the following configurations can be adopted.

(1) A 1 st aspect of the present disclosure provides a numerical controller (for example, a numerical controller 200) that causes a machine tool (for example, a machine tool 100) to perform an operation of performing a thread cutting process of forming a thread on a work object by relatively moving a cutting tool and the work object to perform a plurality of cutting processes on the work object, the numerical controller including:

a drive unit (for example, drive unit 205) for controlling a main shaft for rotating the object to be processed and a 3-axis drive shaft;

a vibration superimposing unit (for example, a vibration superimposing unit 2021) for superimposing vibrations applied to 2 or more of the 3 axes on relative movement between the cutting tool and the machining target so as to vibrate the cutting tool and the machining target relative to each other along the thread groove; and

and a thread cutting vibration adjusting unit (for example, a vibration adjusting unit 2022) for shifting the phase of the vibration with respect to the phase of the main shaft by a predetermined vibration phase shift amount each time during the plurality of times of the cutting.

According to this numerical controller, in thread cutting of a workpiece of a machine tool, by applying vibration to 2 or more axes of the X axis, the Y axis, and the Z axis, it is possible to suppress misalignment due to relative vibration between the cutting tool and the workpiece, improve the accuracy of the finished shape, and suppress the influence on the tip of the cutting tool.

(2) The numerical controller according to item (1) above, wherein the vibration superimposing unit is configured to change a frequency of the vibration.

According to this numerical controller, the frequency gradually increases as the number of times increases, and the irregularities of the thread bottom surface of the workpiece by the thread cutting can be made thin.

(3) The numerical controller according to the above (1) or (2), wherein the vibration superimposing unit is configured to set the amplitude of the vibration according to the cutting depth of each cutting.

(4) The numerical controller according to any one of the above (1) to (3), wherein the vibration superimposing unit vibrates 2 of the 3 axes.

(5) The numerical controller according to any one of the above (1) to (4), wherein the vibration superimposing unit vibrates the 3 axes, and an angle formed between 2 of the 3 axes is 0 ° or more and 90 ° or less.

(6) A 2 nd aspect of the present disclosure provides a machine tool system (for example, a machine tool system 10) including:

the numerical controller (e.g., numerical controller 200) according to any one of (1) to (5) above; and

a machine tool (for example, machine tool 100) moves a cutting tool relative to a workpiece to perform multiple plunge cutting operations on the workpiece to form a thread on the workpiece.

According to this machine tool system, in the thread cutting process of the machine tool on the workpiece, by applying vibration to 2 or more axes out of the X axis, the Y axis, and the Z axis, it is possible to suppress misalignment due to relative vibration between the cutting tool and the workpiece, improve the accuracy of the finished shape, and suppress the influence on the tip of the cutting tool.

(7) A 3 rd aspect of the present disclosure is a numerical control method of a numerical controller (e.g., the numerical controller 200) that causes a machine tool (e.g., the machine tool 100) to perform a thread cutting operation of forming a thread on a work object by moving a cutting tool relative to the work object to perform a plurality of cutting operations on the work object,

a main shaft for rotating the processing object and a driving shaft of 3 shafts are controlled,

superimposing vibrations applied to 2 or more of the 3 axes on the relative movement between the cutting tool and the object to be machined in order to cause the cutting tool and the object to be machined to vibrate relative to each other along the thread groove,

in the multiple cutting, the phase of the vibration is shifted from the phase of the spindle by a predetermined vibration phase shift amount.

According to this numerical control method, in the thread cutting process of the machine tool on the workpiece, by applying vibration to 2 or more axes out of the X axis, the Y axis, and the Z axis, it is possible to suppress misalignment due to relative vibration between the cutting tool and the workpiece, improve the accuracy of the finished shape, and suppress the influence on the tip of the cutting tool.

Description of the reference numerals

10 machine tool system

100 machine tool

101 linear servo motor

102 spindle table

103 spindle motor

104 workpiece

105 linear servo motor

106 support table

107 support column

108 linear servo motor

119 tool table

110 cutting tool

200 numerical controller

201 analysis processing unit

202 interpolation processing unit

203 acceleration/deceleration processing unit

204 control command output unit

205 drive part

2021 vibration superposition section

2022 vibration adjusting part.