JP2902706B2 - Feed control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool feed control device for a machine tool for cutting a workpiece into a non-circular shape.

<Prior Art> A bite feeder of a machine tool for cutting a workpiece into a non-circular shape includes a voice coil type linear motor having an advancing / retracting drive member that moves in an axial direction and a coupling with the advancing / retracting drive member. A table guided by a linear guide so as to be able to move forward and backward, a tool mount fixed on the table, a piezoelectric actuator provided on the tool mount, and a cutting tool driven forward and backward by the piezoelectric actuator. Have been.

Then, based on the non-circular profile data, the tool mount and the cutting tool are respectively advanced and retracted in response to signals input to the linear motor and the piezoelectric actuator, and the operations of the two are combined to immediately generate the non-circular profile data. Then, the cutting tool tip position in the radial direction of the cutting tool is controlled to create and cut a non-circular shape.

<Problems to be Solved by the Invention> In the above-described conventional device, the piezoelectric actuator can obtain a small displacement, but has a hysteresis in the displacement characteristic. Therefore, as a hysteresis damper mechanism, for example, Japanese Unexamined Patent Publication No. 60-48513 discloses As can be seen, there are those using a leaf spring or a viscous fluid. In recent years, a disk-shaped diaphragm holds a movable part that comes into contact with a tool holder and a piezoelectric actuator. Then, the displacement of the movable part is detected by the displacement detection sensor and the piezoelectric actuator is feedback-controlled by the displacement. The displacement of the movable part is caused by the force in the direction perpendicular to the surface of the diaphragm and the displacement of the movable surface by the force of the diaphragm. There is a case where a force for tilting the pattern bite holder is applied in a plane perpendicular to the plane, and in this case, the displacement detection sensor detects the two movements and outputs a false signal to the piezoelectric actuator. is there.

An object of the present invention is to eliminate the output of such an erroneous displacement signal.

<Means for Solving the Problems> In order to achieve the above object, a feature of the present invention is that a diaphragm is fixed to the tip of the ram so as to be flexible in the axial direction, and the diaphragm is fixed to the diaphragm concentrically with the diaphragm. A tool holder provided, an operating member fixed to the diaphragm concentrically with the diaphragm and having a target extended in the radial direction, and a piezoelectric actuator built in the tip of the ram to contact the operating member and drive the tool holder forward and backward And two displacement detection sensors provided at two positions on the tip end surface of the ram so as to face the target; a feed command circuit;
An arithmetic circuit for calculating the displacement of the bite holder in the direction of the ram axis based on the displacement output values from the two displacement detection sensors; and an output of the feed command circuit and an output of the arithmetic circuit to output a deviation signal. And a driving circuit for receiving a deviation signal from the deviation circuit and outputting the signal to the piezoelectric actuator.

<Operation> According to the feed control device having the above configuration, the movement of the target is detected by the two displacement detection sensors, and the output of the two displacement detection sensors is calculated by the arithmetic circuit in the ram axis direction of the bite holder. Calculate the displacement and input the feed command output from the feed command circuit to the deviation circuit where the displacement of the salt bite holder in the ram axis direction is input, and input the deviation signal from the deviation circuit to the drive circuit and from the drive circuit This is output to the piezoelectric actuator to control the piezoelectric actuator.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings. First
In the figure, reference numeral 10 denotes a voice coil type linear motor, which includes a center pole 11 in a motor housing, an advance / retreat drive member 13 loosely fitted to the center pole 11 so as to be able to advance / retreat in the axial direction, and a magnet 12. ing. The advance / retreat drive member 13 is a coil eye having a coil 14 on its outer peripheral surface, and the magnet 12 is fixed in the motor housing so as to face the coil 14.

Reference numeral 15 denotes a guide body, which is installed in front of the linear motor 10. The guide body 15 has a square shaft ram 16 with a hydrostatic bearing 17 for moving the linear motor 10 forward and backward.
The linear motor 10 is guided so as to be able to move forward and backward on the same axis, and its rear end is connected to the forward and backward driving member 13 of the linear motor 10.

As shown in FIG. 2, two diaphragms 18 are fixed to the tip of the ram 16 in parallel with each other in the axial direction so as to be flexible in the axial direction via a spacer 22, and a cutting tool 20 is provided on the front side of the diaphragm 18. Tool holder 19 for holding the diaphragm 18
It is fixed concentrically with.

An operating member 22 is fixedly provided concentrically with the diaphragm 18 on the rear surface side of the diaphragm 18. The operating member 22 has a blade-shaped target 22a extending in the radial direction.

Further, a piezoelectric actuator is provided at the tip of the ram 16.
A built-in member 30 is in contact with the operating member 22. The actuating member 22 always includes the piezoelectric actuator 30 and the diaphragm 18
And is in contact with.

The above-mentioned reciprocating drive member 13, ram 16, piezoelectric actuator 30, bite holder 19 and bite 20 are all reciprocating drive members.
13 is arranged on the same axis 0. By replacing the spacer 21, the operating member 22 is
You can change the preload pressed to 30.
The rear end of the operating member 22 is formed in a curved shape so that the operating member 22 does not tilt following the end surface of the piezoelectric actuator 30.

Further, on the tip end surface of the ram 16, overcurrent-type displacement detection sensors 23A and 23B corresponding to a so-called gap sensor are provided. The two displacement detection sensors 23A and 23B are provided at two contrasting positions about the displacement output axis of the piezoelectric actuator 30, and face the target 22a.

Numeral 24 denotes an advancing / retreating axial movement sensor of the ram 16, a gauge 25 is fixed on the ram 16 side, and a reading head 26 of the gauge 25 is fixed on the guide body 15 side.

Reference numeral 31 denotes a spindle to which the work W is attached, which is rotated by a spindle drive motor 32. Reference numeral 33 denotes a rotary encoder that detects the rotation angle of the main shaft 31.

Next, the configuration of the control circuit of the above device will be described with reference to FIG. 40 is a control device. The control device 40 is connected to the rotary encoder 33 and has an input device 41.
And a memory 42 is connected. This control device 40
Advancing / retreating driving member via a first deviation circuit 43 and a first driving circuit 45
13 is connected to the coil 14 and further another second deviation circuit 4
4. Connected to the piezoelectric actuator 30 via the second drive circuit 46. The first deviation circuit 43 includes the read head.
Connected to 26.

An arithmetic circuit 47 is connected to the second deviation circuit 44, and the arithmetic circuit 47 is connected to the two displacement detection sensors 23A and 23B.

In the device of the present invention having the above configuration, a synchronization signal is input to the control device 40 from the rotary encoder 33,
Profile data is input from the input device 41 and stored in the memory.
Reference numeral 42 stores profile data of high frequency components and profile data of low frequency components.

On the other hand, the control device 40 decomposes into profile data → Fourier series → Fourier series of high frequency components and Fourier series of low frequency components, and performs inverse Fourier to generate profile data of high frequency components and profile data of low frequency components. . Then, the profile data of the high frequency component is output to the first deviation circuit 43, and is output from the first drive circuit 45 to the coil 14 based on the deviation signal from the first deviation circuit 43 to control the linear motor 10. Further, it outputs the profile data of the low frequency component to the second deviation circuit 44. To the second deviation circuit 44, the displacement outputs of the two displacement detection sensors 23A and 23B are calculated to an average value by an arithmetic circuit 47, and the displacement output of this average value is input. Therefore, as shown in FIG.
22a is displaced, and only displacement is detected even if a force in a rotation direction orthogonal to the displacement direction is applied thereto. The second deviation circuit 44 uses the profile data of the low frequency component from the control device 40 and the arithmetic circuit. The deviation signal is output to the second drive circuit 46 on the basis of the averaged displacement output signal from 47 and the piezoelectric actuator 30 is controlled.

Thus, the piezoelectric actuator 30 and the linear motor
10 is controlled by the respective command values, and the operations of both are combined to control the position of the cutting edge in the radial direction of the cutting tool 20 in accordance with the non-circular profile data, thereby cutting the non-circular shape. Things.

In the above-described embodiment, the two displacement detection sensors 23 are used.
A, 23B has been described as an example in which the piezoelectric actuator 30 is provided at two contrasting positions centered on the displacement output axis, but, for example, from the displacement output axis on a diameter line passing through the displacement output axis, Two displacement detection sensors may be provided at a distance separated by a ratio of l1: l2. In this case, the displacement of the tool holder 19 in the ram axis direction is calculated by the following equation.

H: displacement in the ram axis direction l1, l2: distance from the displacement output axis to the displacement detection sensor a, b: output of the displacement detection sensor <Effect of the Invention> As described above, the feed control device of the present invention In particular, based on two displacement detection sensors provided at two positions on the tip end surface of the ram facing the target, a feed command circuit, and displacement output values from the two displacement detection sensors, An arithmetic circuit for calculating the displacement of the bite holder in the direction of the ram axis, a deviation circuit for receiving the output of the feed command circuit and the output of the arithmetic circuit and outputting a deviation signal, and a deviation signal from the deviation circuit. A piezoelectric actuator control circuit comprising a drive circuit for outputting to the piezoelectric actuator, so that a movable part such as a tool holder held by the diaphragm is orthogonal to the surface of the diaphragm. Even if a force for inclining in a plane is applied and a displacement output of an erroneous signal as if displaced is made, this can be removed, and a high-precision feed can be obtained, and as a result, This is to improve the machining accuracy of a workpiece to a perfect circular shape based on profile data.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of the device of the present invention, and FIG. 2 is an enlarged sectional view of a main part. 10 Linear motor, 11 Center pole, 13 Retractable drive member, 15 Guide body, 16 Ram, 18 Diaphragm, 19 Tool holder, 22 Operating member, 22a
…… Target, 23A, 23B …… Displacement detection sensor, 30 ……
Piezoelectric actuator, 40 control device, 44 second deviation circuit, 46 second drive circuit, 47 arithmetic circuit.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor ▲ Sakaki ▼ Norio Hara 1-1-1, Asahi-cho, Kariya-shi, Aichi Prefecture Inside Toyota Koki Co., Ltd. (72) Inventor Yoichi Yamakawa 1-1-1, Asahi-cho, Kariya-shi, Aichi Prefecture (56) References JP-A-1-244511 (JP, A) JP-A-2-212036 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23Q 5/22 B23Q 5/28 B23Q 5/34 B23Q 15/013 G05D 3/00

Claims (1)

(57) [Claims] 1. A diaphragm fixed to the tip of a ram so as to be flexible in the axial direction, a bite holder fixed to the diaphragm concentrically with the diaphragm, and a target fixed radially to the diaphragm concentrically with the diaphragm. A piezo-electric actuator which is built into the tip of the ram and abuts on the operating member to drive the tool holder forward and backward; and a piezoelectric actuator provided at two positions on the tip surface of the ram facing the target. Number of displacement detection sensors, a feed command circuit, a calculation circuit for calculating a displacement of the bite holder in the ram axis direction based on displacement output values from the two displacement detection sensors, and an output and calculation of the feed command circuit A deviation circuit that inputs an output of the circuit and outputs a deviation signal, and a drive circuit that inputs a deviation signal from the deviation circuit and outputs the deviation signal to the piezoelectric actuator. Feed control apparatus characterized by comprising a Ranaru piezoelectric actuator control circuit.