JPH06206144A - Machining device - Google Patents

Abstract

PURPOSE:To permit machining high in precision and having a machining standard part as standard, even if error is generated in the relative position precision between the machining standard part and a chuck part of a workpiece, when the machining is carried out by chucking the workpiece on a work spindle. CONSTITUTION:A video cylinder 15 as workpiece is fixed at the edge part of a revolution spindle 27 supported on a magnetic bearing, and the revolution deflection of a cylinder shaft 17 is measured by a shift sensor 19. On the basis of the result of the measurement, a target position control means outputs the target instruction value of the magnetic bearing for controlling the deflection of the cylinder shaft 17 to a magnetic bearing controller. Accordingly, the revolution spindle 27 is brought under shift-control and the revolution deflection of the cylinder shaft 17 is suppressed. In this state, if the outer peripheral surface of the cylinder is machined, the coaxial machining to the cylinder shaft 17 is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining apparatus for a machining machine having a work spindle equipped with a magnetic bearing.

[0002]

2. Description of the Related Art In recent years, there have been remarkable advances in high-precision machining by machining machines, but the required machining precision has also become more severe.

A conventional processing machine will be described below by taking video cylinder processing as an example. FIG. 2 shows processing of a video cylinder by a conventional NC lathe.

The work spindle 2 and the X-
The Z table 3 is arranged. A work chuck 4 is mounted coaxially on the rotary spindle end surface of the work spindle 2, and the work cylinder 4 chucks a video cylinder 5 as a workpiece. X-Z
A cutting tool is fixed on the table 3, and the cutting tool 6 is moved in the direction of the arrow in the drawing based on a command from an NC controller (not shown in the drawing) to finish the outer peripheral surface of the video cylinder. In this case, as the video cylinder component, the outer peripheral surface of the video cylinder must be finished in a perfect circle coaxial with the video cylinder shaft 7.

[0005]

However, with the above construction, it is not always possible to machine the outer peripheral surface of the cylinder coaxially with the video cylinder axis. This will be described with reference to FIG.

The video cylinder 5 and the cylinder shaft 7 are generally joined by press fitting or shrink fitting. According to this joining method, the coaxiality between the chuck portion 8 and the cylinder shaft 7 can be secured only on the order of several μm. . Therefore, even if the chuck portion 8 is grasped by the ideal chuck 4, whirling occurs in the cylinder shaft 7 with respect to the rotation axis of the work spindle 2, and the coaxiality between the cylinder shaft 7 and the cylinder outer peripheral surface is pressed or burned. There was a problem that it was greatly affected by the fit accuracy.

The present invention solves the above-mentioned problems of the prior art. Even if the cylinder axis and the chuck portion are slightly deviated from each other, the machining apparatus ensures a high degree of coaxiality between the cylinder axis 7 and the cylinder outer peripheral surface. The purpose is to provide.

[0008]

In order to achieve this object, a machining apparatus of the present invention comprises a rotary spindle having an end to which a workpiece is fixed, and an object to detect the position of a machining reference portion of the workpiece. A workpiece position detecting means, an electromagnet that floats the rotating spindle by magnetic force to support the bearing, a rotating spindle position detecting means for detecting the position of the rotating spindle, and a signal from the rotating spindle position detecting means. A magnetic bearing control device that controls the magnetic force of the electromagnet so as to maintain the rotating spindle at a target position, and a signal from the workpiece position detection means is input to automatically set a machining reference portion of the rotating workpiece. In a processing machine equipped with a target position control means for changing the target position of the rotary spindle so as to maintain the target position for machining, the rotary machine is fixed to the end of the rotary spindle. While maintaining the machining reference of the workpiece to the machining reference section target position, and performs predetermined processing.

[0009]

With this construction, the rotary shaft of the magnetic bearing can be dynamically moved in accordance with the rotational position so that the cylinder shaft does not run around, using the cylinder shaft as a machining reference portion.

Therefore, even if the chuck portion and the cylinder axis are slightly deviated from each other, the cylinder axis and the cylinder outer peripheral surface can be improved in concentricity by rotating the cylinder shaft so that it does not swing. it can.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 4, 11 is an NC lathe bed,
Reference numeral 12 is a magnetic bearing supporting work spindle arranged on the bed 1, and 13 is X-Z arranged on the bed 11.
A table, 14 is a work chuck mounted coaxially on the end surface of the work spindle 12, and 15 is a video cylinder component grasped by the work chuck 14, and has a work chuck portion 16 and a cylinder shaft 17 is shrink-fitted. Has been done. Reference numeral 18 denotes a cutting tool fixed on the X-Z table 13, which moves in the direction of the arrow in the drawing along with the movement of the X-Z table based on a command from an NC controller not shown in the drawing, and a video cylinder. The outer peripheral surface is cut and finished. Further, 19 is a displacement sensor for detecting the rotational shake of the cylinder shaft that serves as a machining reference portion of the video cylinder, and 20 is an encoder for detecting the rotational position of the work spindle.

Next, a work spindle supporting a magnetic bearing will be described with reference to FIG. For the sake of simplicity, we will explain about the magnetic bearing in the plane parallel to the paper,
The motion of the magnetic bearing control system is, as shown in the figure, the rotational position around the center of gravity G is θ _y , and the translational positions are X and Z.

In FIG. 1, reference numeral 21 is a casing of the work spindle. Inside the casing 21, a motor stator 22, radial magnetic bearings 23, 24 position detecting displacement sensors 25, 26 are fixed.
The position of the rotary spindle 27 is detected at 6 and is fed back to the magnetic bearing control device 28. Based on this feedback signal, the magnetic bearing control device 28 causes the magnetic bearing 23,
Controlling the electromagnetic attraction force of 24, the rotational position of the rotary spindle θ
_The rotary spindle is levitated and held so that _y and the translational position X become the same as the target command value. The rotating spindle 27 has a motor rotor 29 at a position corresponding to the motor stator portion.
Is fixed.

Further, a thrust magnetic bearing 30 and a thrust position detecting sensor 31 are fixed inside the casing 21, and the sensor 31 detects the thrust direction position Z of the rotary spindle 27 and the magnetic bearing control device 28 is detected. To be fed back. Based on this feedback signal
The magnetic bearing control device 28 controls the electromagnetic attraction force of the thrust magnetic bearing 30 and floats and holds it so that the thrust direction position Z of the rotary spindle becomes equal to the target command value. Reference numeral 19 is the cylinder shaft 1 which serves as the processing reference portion of the video cylinder as described above.
Reference numeral 7 denotes a displacement sensor for detecting the rotational shake of the rotating body 7, and 20 is an encoder for detecting the rotational position of the work spindle.

Reference numeral 29 is a target position control means, which inputs the rotational position signal of the rotary spindle 27 detected by the encoder 20 and the whirling amount of the cylinder shaft 17 detected by the displacement sensor 19 in synchronization therewith. Further, based on these input information, in order to remove whirling of the cylinder shaft 17, it is calculated how the rotary spindle 27 should be moved (X-θ _y movement) in the magnetic bearing space. Ask.
The obtained result is the target command value in the magnetic bearing control system for the magnetic bearing controller.

[0017]

[Equation 1]

It is given as The target command value (Equation 1)
Generally changes according to the rotational position of the rotary spindle 27.

FIG. 5 shows a state in which the rotary spindle 27 is whirling to prevent the cylinder shaft 17 from swinging. If the outer peripheral surface of the cylinder is machined in this state, machining coaxial with the cylinder shaft 17 will be performed. it can.

Next, the method for the target position control means 29 to obtain the target command value (Equation 1) for removing the whirling of the cylinder shaft 17 will be described in detail.

Since it is difficult for the target position control means 29 to eliminate the whirling of the cylinder shaft 17 by only one measurement and calculation, in this embodiment, the rotational position detection of the rotary spindle and the whirling of the cylinder shaft 17 are performed. A method is adopted in which the whirling of the cylinder shaft is asymptotically reduced by repeatedly measuring the amount, calculating the target command value of the magnetic bearing control system based on this data, and learning the output to the control device. This method will be described below.

FIG. 6 shows the processing contents of the target control means. First, in the initial setting, the number of times n of control is repeated and the target command value to be output to the translational motion and rotational motion of the magnetic bearing control system.

[0023]

[Equation 2]

(I = 1 ... m: i is a subscript indicating a rotational position)
Is set to 0. Then enter the iterative control loop,
Target command values for translational and rotational motion of magnetic bearing control system

[0025]

[Equation 3]

Is output to the magnetic bearing control device to move the rotary spindle in the magnetic bearing space in correspondence with the rotational position (however, it does not move when n = 0). The rotational runout of the cylinder shaft at this time

[0027]

[Equation 4]

The rotary position φ of the rotary spindle_iCorresponding to
Input from the displacement sensor. u_a, U _bEtc. defined in Fig. 7
To do. The degree of this rotational runout, the number of repetition control
Whether to end the iterative control according to the convergence status
decide. If it is determined that the control will be repeated,
Target value of rotational runout of the shaft

[0029]

[Equation 5]

Deviation from

[0031]

[Equation 6]

Whether or not there is found by the following calculation.

[0033]

[Equation 7]

The calculated deviation (Equation 6) is converted into a deviation signal of the magnetic bearing control system by the functions f and g.

[0035]

[Equation 8]

Convert to After filtering such as noise removal, the target command value to be output to the magnetic bearing controller next time.

[0037]

[Equation 9]

Is calculated by the following calculation.

[0039]

[Equation 10]

Finally, the number of repetition control is increased by 1,
Return to the output of the target command value (Equation 3) to the magnetic bearing control value.

The functions f and g are generally shown below.

[0042]

[Equation 11]

P is a constant, translational motion x and rotational motion θ
and performs a vertical viewing pickled between _y, the second term first equation right side is for alleviating the impact of movement of the rotary movement gives the movement of translation.

By performing the above repetitive control,
The whirling of the cylinder shaft can be controlled by dynamically controlling the movement of the rotary spindle. If the cylinder outer peripheral surface is machined in this state, the coaxiality between the cylinder shaft 17 and the cylinder outer peripheral surface is dramatically improved.

As described above, according to the present embodiment, by moving the rotary spindle that supports the magnetic bearing, it is possible to prevent the cylinder shaft, which is not coaxial with the chuck portion, from swinging around, and the cylinder which is the machining reference portion. High-precision machining based on the axis can be realized.

[0046]

As described above, according to the present invention, the position of the machining reference portion of the rotating workpiece is measured, and based on this information, the work spindle shaft of the magnetic bearing is moved to rotate the workpiece. The machining reference part of the workpiece can be maintained at a certain target position, and for some reason the machining reference causes an error in the relative position accuracy of the chuck part of the workpiece, or a minute foreign substance is present between the chuck and the workpiece. Even if they are mixed, an excellent processing apparatus that can perform processing with the processing reference portion as a reference with high accuracy is realized.

[Brief description of drawings]

FIG. 1 is a main configuration diagram of a processing apparatus according to an embodiment of the present invention.

FIG. 2 is a main configuration diagram of a conventional video cylinder processing apparatus.

FIG. 3 is a diagram for explaining the problems of the conventional video cylinder processing apparatus.

FIG. 4 is an overall view of a processing apparatus according to an embodiment of the present invention

FIG. 5 is a diagram of a work spindle for explaining the operation of the processing apparatus according to the embodiment of the present invention.

FIG. 6 is a flowchart of the processing contents of the target position control means in the embodiment of the present invention.

FIG. 7 is an explanatory diagram of signals in the embodiment of the present invention.

[Explanation of symbols]

 12 Work Spindle 15 Video Cylinder 17 Cylinder Axis 19 Displacement Sensor 27 Rotating Spindle 28 Magnetic Bearing Control Device 29 Target Position Control Means

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Takafumi Asada 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kazuhiro Okawa, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A rotary spindle having a workpiece fixed to an end thereof, a workpiece position detecting means for detecting a position of a machining reference portion of the workpiece, and a bearing which floats the rotary spindle by a magnetic force. A supporting electromagnet, a rotary spindle position detecting means for detecting the position of the rotary spindle, and a signal from the rotary spindle position detecting means to control the magnetic force of the electromagnet so as to maintain the rotary spindle at a target position. The target position of the rotating spindle is changed so that the machining reference portion of the rotating workpiece is automatically maintained at the machining reference portion target position by inputting a signal from the magnetic bearing control device and the workpiece position detection means. In the machining apparatus including the target position control means, the machining reference portion of the workpiece fixed to the rotary spindle end is maintained at the machining reference portion target position. A processing device characterized by performing constant processing. 2. The rotation position detecting means for detecting the rotation position of the rotary spindle according to claim 1, wherein the position of the machining reference portion of the workpiece inputted corresponding to the rotation position of the rotary spindle and the predetermined workpiece are determined. In a processing apparatus having a target position control means for changing a target position of a rotary spindle based on a difference from a target position of a machining reference part of a workpiece, a machining reference part of a workpiece fixed to an end of the rotary spindle. A processing apparatus which performs a predetermined processing while maintaining the target position of the processing reference portion. 3. The position of the machining reference part is repeatedly learned based on the difference between the position of the machining reference part measured corresponding to the rotational position of the rotary spindle and the target position of the machining reference part. In a processing apparatus equipped with a target position control means for changing a target position of a rotary spindle so as to asymptotically approach a target position of a machining reference part, a machining reference part of a workpiece fixed to an end of the rotary spindle is set to a target position of the machining reference part. A processing apparatus which performs predetermined processing while maintaining the temperature.