JP2863689B2 - Processing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing machine provided with a magnetic bearing spindle.

[0002]

2. Description of the Related Art Conventionally, there is a magnetic bearing spindle that supports a rotating shaft in a non-contact manner by the magnetic force of an electromagnet. This magnetic bearing spindle is excellent in high-speed rotation because the rotating shaft is supported in a non-contact manner, and also uses the electronic control function of the rotating shaft when grinding a grinding wheel on the inner surface of a cylinder using a quill. (Japanese Patent Laid-Open No. Hei 3
-86469).

[0003]

However, in the control device of the magnetic bearing spindle disclosed in the above-mentioned publication, control corresponding to a change in processing steps (processing conditions) such as roughing and finishing is not performed. For this reason, a large force or displacement is required in rough machining with a large grinding load, and as a result, the correction value becomes incorrect due to the occurrence of saturation or the like. The present invention has been made based on the above circumstances, and an object of the present invention is to perform optimal control in a processing machine having a magnetic bearing spindle according to a change in processing conditions of a workpiece.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a machining method for machining a workpiece at the tip.
The quill on which the tool is mounted and the quill
Rotary axis lifting, and a magnetic bearing spindle having a magnetic bearing for rotatably supporting while being floated said rotary shaft by a magnetic force generated by the exciting current flows, the rotation by controlling the excitation current flowing through the magnetic bearing A control device for varying the position of the shaft, the control device,
A rotating shaft position detecting means for detecting a position of the rotating shaft in the magnetic bearing spindle, and an excitation flowing through the magnetic bearing
The amount of deflection of the quill detected by an electric current and the rotation
The machining at the time of machining from the detected value of the shaft position detecting means
Tool position detecting means for detecting the position of the tool
Machining shape measuring means for measuring the machining shape of the workpiece from the detected value of the tool position detecting means detected by the tool position detecting means, and the machining shape of the workpiece measured by the machining shape measuring means and the workpiece Grinding load based on comparison with target shape
Control gain calculating means for calculating respective control gains corresponding to roughing with a large load and finishing with a small grinding load ;
Processing condition detecting means for detecting whether the processing condition of the workpiece is rough processing or finishing processing, and corresponding to the processing condition detected by the processing condition detecting means from each control gain calculated by the control gain calculating means. Control gain determining means for determining a control gain to be performed;
When the machining conditions are rough machining, the control gay
The amount of correction to the workpiece based on the
Controlling the exciting current flowing through the magnetic bearing,
When the processing conditions detected by the detection means are finishing,
The workpiece based on the control gain corresponding to the finishing
Technical means is provided with exciting current control means for controlling an exciting current flowing through the magnetic bearing so as to increase the amount of correction to the magnetic bearing.

[0005]

According to the working machine of the present invention having the above-described structure,
Detects whether the processing condition of the object is rough or finish
Is roughing, the control gain based on the roughing is used.
Magnetic bearings to reduce the amount of correction to the workpiece
Excitation current flowing is controlled, and when the processing conditions are finishing,
Workpiece based on the control gain corresponding to the finishing
Excitation current flowing through the magnetic bearing to increase the amount of correction
Can be controlled. In addition, the control gate corresponding to the roughing
The control gains corresponding to the
Well-known calculation based on the comparison between the machining shape of the target and the target shape
It can be obtained by means. Processing of workpiece
The position of the machining tool required to measure the shape is
Shaft position (detected value of rotation axis position detecting means) and quill deflection
Calculated by the amount of excitation (excitation current flowing through the magnetic bearing)
Can be.

[0006]

Next, an embodiment of a processing machine according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of the processing machine. The processing machine 1 of the present embodiment is an inner surface grinding machine for grinding a cylindrical inner peripheral surface of a work 2 (workpiece), and a magnetic bearing spindle 4 for rotatably supporting a grinding wheel 3 (processing tool). A control device 5 (described later) for the magnetic bearing spindle 4 is provided.

The magnetic bearing spindle 4 includes a rotary shaft 6 having a flange portion 6a provided on the outer periphery thereof, and a radial electromagnet 7 (a main body) disposed on outer circumferential portions of both ends of the rotary shaft 6 so as to float and support the rotary shaft 6. The present invention includes a magnetic bearing of the present invention), a motor 8 for driving the rotary shaft 6 to rotate, an axial electromagnet 9 for regulating the axial displacement of the rotary shaft 6 via a flange 6a of the rotary shaft 6, and the like. A quill 10 is provided coaxially with the rotating shaft 6 at the tip (left end in FIG. 1) of the rotating shaft 6, and the grindstone 3 is attached to the tip of the quill 10. The rotating shaft 6 is supported by a protective bearing (not shown) when the radial electromagnet 7 is cut off and the magnetic levitation force is lost.

A total of four radial electromagnets 7 are arranged above and below and to the right and left of the rotating shaft 6, respectively, and the magnetic force changes according to the magnitude of the exciting current. Therefore, by controlling the exciting current of each radial electromagnet 7, the rotating shaft 6
Can be biased and supported. The magnetic bearing spindle 4 is provided with a position sensor 11 for detecting the position of the rotating shaft 6 in the radial direction and a position sensor 12 for detecting the position of the rotating shaft 6 in the axial direction. The position sensors 11 are arranged close to the outer peripheral surfaces of both ends of the rotating shaft 6, respectively, and the position sensor 12 is arranged close to the rear end surface (the right end surface in FIG. 1) of the rotating shaft 6.

As shown in FIG. 2, the magnetic bearing spindle 4 is fixedly supported on an oscillation table 13 so that the oscillation table 13 can move in the axial direction of the magnetic bearing spindle 4 with respect to the bed frame 14. Is provided. A work table 16 provided with a chuck device 15 for supporting the work 2 is mounted on an end of the bed frame 14, and the work table 16 is perpendicular to the moving direction of the oscillation table 13 with respect to the bed frame 14. It is provided movably in the direction.
Therefore, by moving the oscillation table 13 and the work table 16 with respect to the bed frame 14, the relative position between the work 2 and the grindstone 3 changes. In addition,
The work 2 supported by the chuck device 15 is driven to rotate by a motor (not shown). In addition, bed frame 1
4 is provided with an oscillation detection sensor 17 (see FIG. 1) for detecting the position of the oscillation table 13.

The control device 5 includes, in addition to the position sensor 11, the position sensor 12, and the oscillation detection sensor 17,
It comprises a grinding machine control unit 18, a magnetic bearing controller 19, a machining shape measurement unit 20, a corrected waveform generation unit 21, a control gain output unit 22, and a control signal calculation unit 23. The grinding machine control unit 18 (processing condition detecting means of the present invention) outputs a processing step switching signal Ks for instructing switching of the processing step (in this embodiment, rough processing and finish processing).

The magnetic bearing controller 19 controls an exciting current flowing through the radial electromagnet 7 and the axial electromagnet 9, and converts a detection value of each of the position sensors 11 and 12 into a displacement signal Hs. The displacement signal Hs converted at 19a and the control signal S calculated at the control signal calculation unit 23 are adjusted by PID (proportional +
PID circuit 19b that calculates current signal Ds by performing integration + differential operation), and current signal D obtained by PID circuit 19b.
It comprises a power amplifier circuit 19c that amplifies s and outputs it to each radial electromagnet 7 and axial electromagnet 9.

The machining shape measuring section 20 is provided with a displacement signal Hs converted by the sensor circuit 19a of the magnetic bearing controller 19.
A / D converter 20a, which converts PID into a digital signal, PID
A / D converter 20b for converting current signal Ds obtained by circuit 19b into a digital signal, based on the digital signal converted by A / D converter 20a and the digital signal converted by A / D converter 20b you measure the machining shape of the workpiece 2 are formed of a machining shape measuring circuit 20c. The work
The machining shape of 2 is the data of the entrance and the back of the inner peripheral surface of the work 2.
(That is, the position of the grindstone 3)
It is. The position of the grinding wheel 3 is determined by the position of the rotating shaft 6 (displacement signal).
Hs) and the amount of deflection of the quill 10 (current signal Ds).
(Tool position detecting means of the present invention).

A corrected waveform generating section 21 stores a corrected waveform for one oscillate for a presumed processing shape of the workpiece 2 (a processing shape when the shape is not corrected during the processing). And a waveform output timing circuit 21b for outputting the corrected waveform stored in the corrected waveform storage section 21a in synchronization with the oscillation of the magnetic bearing spindle 4. In addition, the waveform for one oscillation is a waveform corresponding to the processing shape of the workpiece 2 processed while the oscillation table 13 makes one reciprocation.

The control gain output unit 22 includes a zero point detection circuit 22a for detecting a zero point of the waveform output from the corrected waveform storage unit 21a, and a machining shape (taper value) of the workpiece 2 measured by the machining shape measuring circuit 20c. The control gain calculators 22b and 22c, which calculate control gains (rough machining gain and finishing machining gain) according to the machining process, based on the comparison between the control gain and the target shape of the workpiece 2, are output from the grinding machine controller 18. The control gain determining unit 22d that determines the control gain in response to the machining process switching signal Ks, and switches the control gain (the control gain determined by the control gain determining unit 22d) at the zero point detected by the zero point detection circuit 22a. And a control gain output timing circuit 22e. Note that the roughing gain is set so that the amount of correction to the workpiece 2 is reduced during roughing, and the finishing gain is set so that the amount of correction to the workpiece 2 is increased during finishing. (See FIG. 4).

The control signal calculation unit 23 includes a modified waveform generation unit 2
1 is multiplied by the control gain output from the control gain output unit 22 to obtain a control signal S,
This control signal S is output to the PID circuit 19b of the magnetic bearing controller 19.

Next, the operation of this embodiment will be described with reference to a flowchart shown in FIG. 3 and a time chart shown in FIG. First, when the machining is started, a synchronization signal synchronized with the oscillation of the magnetic bearing spindle 4 is detected by the oscillation detection sensor 17 (step S).
1 and YES). Subsequently, the displacement signal Hs and the PID converted by the sensor circuit 19a of the magnetic bearing controller 19
The current signal Ds obtained by the circuit 19b is extracted (step S2), and the work 2 is obtained from the displacement signal Hs and the current signal Ds.
Is measured (step S3).

Subsequently, the machining process is determined based on the machining process switching signal Ks output from the grinding machine control unit 18 (step S4), and a control gain corresponding to each machining process (rough machining, finish machining) is calculated. I do. That is, in the case of rough machining, the gain for rough machining is calculated by the control gain calculator 22b (step S5), and in the case of finish machining, the gain for finish machining is calculated by the control gain calculator 22c (step S6). Subsequently, a zero point of the corrected waveform output in synchronization with the oscillation of the magnetic bearing spindle 4 is detected from the corrected waveform storage unit 21a (YES in step S7), and the control gain (according to the machining process) is obtained at that timing. Switching of the calculated control gain is performed (step S8). As described above, by switching the control gain at the zero point of the waveform, it is possible to prevent the occurrence of a step on the processing surface of the work 2.

Subsequently, the control signal S obtained by multiplying the corrected waveform output from the corrected waveform generator 21 by the control gain output from the control gain output unit 22 is sent to the PID circuit 19 b of the magnetic bearing controller 19. Then, the excitation current to each radial electromagnet 7 and axial electromagnet 9 is controlled (step S9). The above operation is performed for each oscillation, and after grinding is performed until a target shape is obtained (YES in step S10), the processing is terminated.

As described above, in this embodiment, the control gain according to the machining process is calculated, and the control gain is varied between the rough machining and the finish machining, thereby outputting the optimum control gain in each process. (See FIG. 4). As a result, the shape of the work 2 can be prevented from deteriorating by reducing the amount of correction to the work 2 during rough machining, and the shape can be corrected by increasing the amount of correction to the work 2 during finish machining. Accurate machining can be realized.

[Modification] In this embodiment, an example in which the control gain is varied according to the machining process has been described. However, a method for determining the control gain based on a factor that changes the machining condition of the work 2 other than the machining process May be varied. Factors that change the processing conditions include the number of processing after dressing,
An axis number in a multi-axis grinding machine, an average of several previous taper values (processed shapes) measured in a host process, and the like can be considered.
The machining process switching signal Ks can also be created by detecting the grinding load from the electromagnet current of the magnetic bearing.

In the above-described embodiment, the example in which the shape of the work 2 is corrected for each oscillation of the magnetic bearing spindle 4 has been described. However, the shape in the rotation direction can be corrected by a signal synchronized with the rotation of the work 2. is there. Oscillation detection sensor 1 for detecting oscillation of a magnetic bearing
Although the number 7 is provided, the oscillation may be detected by a signal output from the NC, the sequencer, the sizing device, the Z-axis sensor of the magnetic bearing spindle 4, or the like. The accuracy of the determination of the control gain can be improved by using a differential element, an integral element, and the like. The correction waveform stored in the correction waveform storage unit 21a can be changed for each part number of the work 2.

[0022]

The processing machine according to the present invention can output an optimum control gain according to each processing condition by changing the control gain according to the processing condition of the workpiece to be estimated in advance. . As a result, occurrence of saturation can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a processing machine according to a first embodiment.

FIG. 2 is a perspective view of a processing machine 1 (internal grinding machine).

FIG. 3 is a flowchart showing the operation of the first embodiment.

FIG. 4 is a time chart according to the operation of the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing machine 2 Workpiece (workpiece) 3 Grinding stone (machining tool) 4 Magnetic bearing spindle 5 Control device 6 Rotary shaft 7 Radial electromagnet (magnetic bearing) 11 Position sensor (rotary shaft position detecting means) 12 Position sensor (rotary shaft) Position detection means) 18 Grinding machine control unit (processing condition detection means) 19 Magnetic bearing controller (excitation current control means) 20 Processing shape measurement unit (processing shape measurement means) 22b Control gain calculation unit (control gain calculation means) 22c Control gain Calculation part (control gain calculation means) 22d Control gain determination part (control gain determination means)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Niimi 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (72) Inventor Shinzo Ito 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Japan Denso (56) References JP-A-3-86469 (JP, A) JP-A-59-89820 (JP, A) JP-A-5-16068 (JP, A) JP-A-3-228570 (JP, A) A) JP-A-1-234162 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B24B 49/04 B23B 19/02 B23Q 15/02 F16C 32/04

Claims (1)

(57) [Claims] 1. A machining tool for machining a workpiece at the tip.
A quill to which the tool is attached, a rotating shaft that coaxially supports the quill , and a magnetic bearing spindle having a magnetic bearing that supports the rotating shaft in a floating state by a magnetic force generated when an exciting current flows, A control device that controls an exciting current flowing through a magnetic bearing to vary a position of the rotary shaft, the control device comprising: a) detecting a position of the rotary shaft in the magnetic bearing spindle; Rotating shaft position detecting means; b) detected by an exciting current flowing through the magnetic bearing
The amount of deflection of the quill and the value detected by the rotating shaft position detecting means
Detects the position of the machining tool during machining from
Tool position detecting means; c) detection of said tool position detecting means detected at a plurality of points.
Machining shape measuring means for measuring the machining shape of the workpiece from the value ; d) based on a comparison between the machining shape of the workpiece measured by the machining shape measuring means and a target shape of the workpiece. Roughing with large grinding load and finishing with small grinding load
A control gain calculating means for calculating the control gain of each corresponding to the factory, e) wherein the machining condition detecting means for processing condition of the workpiece to detect whether roughing or finishing, f) in the control gain calculating means A control gain determining means for determining a control gain corresponding to the processing condition detected by the processing condition detecting means from each of the calculated control gains; and g) a processing condition detected by the processing condition detecting means.
At the time of machining, based on the control gain corresponding to the rough machining
The magnetic bearing so as to reduce the amount of correction to the workpiece
Control the exciting current flowing through the
If the processing conditions issued are for finishing,
The amount of correction to the workpiece based on the corresponding control gain.
Processing machine, characterized in that an excitation current control means for controlling the excitation current flowing through the magnetic bearing so as to increase.