JP2849956B2 - Grinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding machine for grinding an inner peripheral surface or an outer peripheral surface of a work by oscillating a grindstone, and more particularly to a technique for finishing a desired work to a cylindrical degree in a short time.

[0002]

2. Description of the Related Art Conventionally, in a grinding machine of this type, when a grinding wheel is oscillated to perform an inner surface grinding or the like of a work, a grinding shaft is bent by a grinding load. It tends to have smaller cylindricity.

Therefore, when performing the above-described internal grinding, for example, as described in Japanese Patent Application No. 2-69088, the cylindricity of the work is detected at the same time as the internal grinding, and the cylindricity of the work is detected. Switching to the appropriate grinding cycle corrects the cylindricity of the work. In addition, as the grinding cycle that can be switched, for example, there is a grinding cycle in which the fine polishing speed, the retraction amount, and the like are changed according to the cylindricity of the work.

[0004]

However, such a conventional grinding machine is configured to correct the work cylindricity by switching to a grinding cycle corresponding to the work cylindricity. However, it is inevitable that the grinding time up to the desired cylindricity depends on the grinding performance of the grindstone. As a result, when the grinding performance of the grindstone is reduced, the above-described disadvantage that the grinding time becomes longer is caused. Occurs.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to forcibly adjust the cylindricity of a work by inclining a grindstone relative to the work. In order to achieve the above object, the present invention provides an inner peripheral surface of a workpiece by oscillating a grindstone in an axial direction to achieve the above object. In a grinding machine for grinding an outer peripheral surface, a cylindricity measuring means for measuring a cylindricity of a work from a difference in grinding force between a forward end and a backward end of the oscillation operation, and
Of the grinding force corresponding to the cylindricity of the
Comparison with the set amplitude set value, and based on the difference,
And a tilting means for tilting the rotor shaft, on which the grindstone is mounted, relative to the workpiece and geometrically in a direction in which the cylindricity of the workpiece is reduced.

[0006]

SUMMARY OF] According to the present invention, the cylindricity measurement means, Oscillator
End of the motion (the point where the grindstone is
Position) and the reverse end (the position where the grindstone is at the mouth of the work)
From the difference (amplitude) of the grinding force
Detects a slight deterioration in cylindricity of the tool, and removes the grinding wheel based on this.
The attached rotor shaft is tilted relative to the workpiece and geometrically in a direction to reduce the cylindricity of the workpiece.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a grinding machine according to the present invention will be described below in detail with reference to FIGS.

This grinding machine has a headstock table 1 and a grinding wheel table 2 as shown in FIG. 1. The headstock table 1 can move forward and backward along the axis X direction, and the grinding wheel table 2 moves in the axis Z direction. It is provided to be able to move forward and backward along.

A cylindrical work 3 is disposed on the headstock table 1, and the work 3 is rotatably held by a support mechanism (not shown). On the other hand, a magnetic bearing type spindle unit 4 is installed on the grindstone table 2. A grindstone 6 is attached to a rotor shaft 5 of the spindle unit 4, and a circle is formed near the center of the rotor shaft 5 in the longitudinal direction. The shape thrust disk 7 is formed integrally.

Further, on the outer peripheral surface side of the rotor shaft 5,
A set of radial magnetic bearings 8, 8 is provided, and each radial magnetic bearing 8 is provided with four radial electromagnets 8a to 8d and radial position sensors 8e to 8h as shown in FIG.
Of these four radial electromagnets, the two facing radial electromagnets 8a and 8c and the radial electromagnets 8b and 8d are respectively configured to operate as a pair, and the four radial direction position sensors 8e to 8h are also the same. , Two radial position sensors 8e facing each other,
8g and the radial position sensors 8f and 8h are configured to operate as a pair.

The two pairs of radial electromagnets and the radial position sensor are installed at an angle of 90 degrees about the center of the rotor shaft.

On the other hand, a set of axial magnetic bearings 9 is provided around the thrust disk 7, and the axial magnetic bearing 9 includes two donut-shaped axial electromagnets 9a and 9b and an axial direction position sensor 9c. These axial electromagnets 9a and 9b are installed so as to face each other via a thrust disk 7, while the axial direction position sensor 9c is
It is arranged on the end face side.

Incidentally, the radial position sensors 8e to 8h and the axial position sensor 9c as described above are used.
, The respective sensor detection values S _1, S ₁ ..., the control unit 1 to S ₂
0, respectively, and the control unit 10 will be described next.

The control unit 10 is provided with a position detecting circuit 11, which receives the sensor detected values S ₁ , S _1, ..., S _{2 and} outputs both ends 5a, 5 of the rotor shaft.
The radial floating positions h _R1 and h _R2 and the axial floating position h _A1 of b are obtained and output to the processing circuit 12.

The processing circuit 12 includes both ends 5a, 5b of the rotor shaft.
The target positions h _R0 , h _R0 in the radial direction are stored, and the target position h _R0 is compared with the radial floating position h _{R1 of the} rotor shaft end 5a to amplify the comparison deviation δ _R. And outputs it to the electromagnet driver 13. Electromagnet driver 13 compares the deviation [delta] _R component of the excitation current i
_R is output to the radial electromagnets 8a to 8d. At the same time, the processing circuit 12 is configured to perform the same processing as described above for the radial floating position h _R1 of the other end 5b of the rotor shaft.

The processing circuit 12 stores a target position h _A0 of the rotor shaft 5 in the axial direction, compares the target position h _A0 with the axial floating position h _A1 , output to the electromagnet driver 13 amplifies the [delta] _a, the electromagnet driver 13 outputs an excitation current i _a comparison deviation [delta] _a partial axial electromagnet 9a, to 9b.

Thus, the radial electromagnets 8a to 8a
d and the axial electromagnets 9a and 9b are excited,
The rotor shaft 5 is supported at a predetermined position in a non-contact manner.

The control unit 10 further includes a grinding force detection circuit 1
The grinding force detection circuit 14 detects the grinding force by utilizing the fact that the change in the exciting currents i _R and i _A is equal to the change in the grinding force in the grinding wheel 6. The grinding force is applied to the bandpass filter 15 to remove the roundness component generated by the rotation of the work.
Is output as a grinding force signal S _F to the cylindricity measuring unit 16 via the.

[0019] Here, for example, when the grinding wheel 6 by oscillation operation performed internal grinding of the workpiece 3, the waveform of the grinding force signal S _F as described above, in synchronism with the oscillation operation as shown in FIG. 3 Then, it increases when the grindstone advances toward the back of the work (the forward end of the oscillation operation), and decreases when the grindstone returns to the mouth of the work (the backward end of the oscillation operation). If the magnitude difference of such a waveform is an amplitude W, the amplitude W is as shown in FIGS.
As shown in the order of (c), the smaller the work cylindricity θ becomes, the smaller the work cylindricity θ becomes. This occurs because the magnitude of the deflection of the grinding wheel shaft changes depending on the magnitude of the grinding load. That is, when the grinding load is large, the amount of deflection is large,
This is because, when the grinding load is small, the amount of deflection of the grindstone is small, and the amount of the grinding stone escaping from the work is small. Further, the amplitude W and the cylindricity θ of the work have a linear relationship as shown in FIG. That is, the magnitude fluctuation of the amplitude W corresponds to the magnitude of the cylindricity θ of the work.

[0020] Therefore, the cylindrical measuring unit 16 is configured so as to measure the cylindricity of θ of current work by detecting the amplitude W of the grinding force signal S _F as described above.

The control unit 10 is provided with a shaft tilt angle detecting unit 17 and a tilt angle setting unit 18 as tilting means. The direction floating positions h _R1 and h _R2 (related to both ends 5a and 5b of the rotor shaft) are input, and
The current rotor shaft inclination angle α ₁ is detected based on these radial floating positions h _R1 and h _R2, and is detected by the grinding machine NC unit 19.
Output to

On the other hand, the inclination angle setting section 18 calculates the rotor shaft inclination angle α based on the cylindricity θ of the work as described above. Here, the cylindricity θ and the amplitude W of the work are calculated.
Has a linear relationship as described above, the rotor shaft inclination angle α is calculated based on the amplitude W instead of the work cylindricity θ,
This is output to the grinding machine NC unit 19.

The tilt angle setting section 18 stores a rotor shaft tilt angle initial value α ₀ , an amplitude set value W _0, and a correction coefficient K _0, which will be described later, as set values. The calculation processing operation of the shaft inclination angle α is performed based on a flowchart as shown in FIG.

The grinding machine NC unit 19 is provided with new target positions h _R1 and h _R in the radial direction of both ends 5a and 5b of the rotor shaft.
_R1 is obtained and output to the processing circuit 12. These new target positions h _R1 and h _R1 are obtained by calculating the rotor shaft inclination angle α and the current rotor shaft inclination angle α of the calculation result as described above.
₁ is required to be equal.

The high frequency motor 30 rotates the rotor shaft 5 and is driven by a motor driver 31.

Next, the operation of the grinding machine configured as described above will be described with reference to the flowchart shown in FIG. However, in this grinding machine, the grinding wheel 6 moves forward and backward, whereby the grinding wheel 6 performs an oscillating operation and the work 3
It is assumed that the inner surface has been ground.

According to this grinding machine, when the amplitude W corresponding to the cylindricity of the current work is input from the cylindricity measuring unit 16 to the inclination angle setting unit 18 (step 100), the inclination angle setting unit 18 after subtracting the amplitude setting value W ₀ from the amplitude W, by comparing the subtraction result with 0 (step 10
2) If the comparison result is larger than 0 (Yes), that is, if the cylindricity of the current work is larger than the cylindricity of the work corresponding to the amplitude set value W ₀ , the rotor shaft inclination angle α
Is obtained from equation (1) (step 104), and is output from the inclination angle setting unit 15 to the grinding machine NC unit 19 (step 106).

Α = α ₀ + K ₀ (W ₁ −W ₀ ) (1) where α _{0 is the} initial value of the rotor shaft inclination angle (the angle between the axis of the workpiece and the axis of the grindstone set before the start of grinding). K ₀ correction coefficient (inclination of the proportional straight line shown in FIG. 5) W ₀ amplitude set value (amplitude of grinding force corresponding to target cylindricity) W ₁ current amplitude At the same time, the shaft inclination angle detection unit 17 performs grinding. Panel NC unit 1
9 are output current of the rotor shaft angle of inclination alpha ₁ to, in this grinding machine NC unit 19, the current of the rotor shaft angle of inclination alpha ₁
There obtains a new target value h _R1, h _R1 to be equal to α rotor shaft angle of inclination of the above-described calculation result, and outputs it to the processing circuit 12.

Thus, the rotor shaft 5 and the grindstone 6
Are tilted relative to the work 3 at the rotor shaft tilt angle α of the calculation result. That is, as shown in FIG. 7, the amount of deflection of the grindstone shaft is estimated in advance, and the grindstone 6 is geometrically inclined in a direction in which the cylindricity of the work becomes smaller, thereby forcibly correcting the cylindricity of the work.

On the other hand, when the comparison result is smaller than 0 (No), that is, when the cylindricity of the current work is smaller than the cylindricity of the work corresponding to the amplitude set value W ₀ ,
As the rotor shaft inclination angle α, the rotor shaft inclination angle initial value α ₀
Is set (step 108), and this is set to the tilt angle setting unit 18
The output is sent to the grinding machine NC unit 19 (step 106).

At this time, the new target values h _R1 and h _R1 are calculated in the grinding machine NC unit 19 so that the current rotor shaft inclination angle α ₁ is equal to the rotor shaft inclination angle initial value α ₀ . The inclination angles of the rotor shaft 5 and the grindstone 6 return to the initial state.

Therefore, according to such an embodiment,
The rotor shaft inclination angle is calculated based on the amplitude corresponding to the work cylindricity, and the rotor shaft and the grindstone are moved relative to the work and geometrically in such a direction that the work cylindricity becomes smaller. Because of the inclination, the cylindricity of the work is forcibly corrected, so that the grinding time until reaching the desired work cylindricity can be reduced.

FIG. 8 shows a second embodiment of the grinding machine according to the present invention. The same members as those in the first embodiment are designated by the same reference numerals, and the detailed description thereof will be omitted. I do.

In this grinding machine, a spindle unit 4 is mounted on a grinding wheel table 2 via a spindle mounting table 20, and the spindle mounting table 20 is rotatable about the point a on the grinding wheel table 2. Is provided.

That is, in such a grinding machine, the spindle mount 20 is rotated by the servo motor driver 21 and the servo motor 22 so that the grindstone 5 of the spindle unit 4 is tilted relatively to the work W. It is configured.

In this apparatus as well, as in the first embodiment, the inclination angle setting section 18 performs the arithmetic processing of the flowchart shown in FIG. 6, but in this case, the rotor shaft inclination angle initial value α ₀ is set to the initial value. Instead, the spindle unit inclination angle initial value β ₀ is used. Thus, in such an apparatus, the spindle unit inclination angle β is calculated based on the amplitude W corresponding to the cylindricity of the work, and the spindle unit inclination angle β
, The spindle mount 20 is configured to rotate.

FIG. 9 shows a third embodiment of the grinding machine according to the present invention. The same members as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. I do.

In this grinding machine, a work holding mechanism (not shown) is mounted on the headstock table 1 via a holding mechanism mounting table 23, and the holding mechanism mounting table 23 is centered on point b on the headstock table. It is provided rotatably.

That is, in such a grinding machine, the holding mechanism mount 23 is rotated by the servo motor driver 24 and the servo motor 25 so that the grindstone 5 of the spindle unit 3 is relatively inclined with respect to the work W. Is configured.

In this apparatus as well, as in the first embodiment, the inclination angle setting section 18 performs the arithmetic processing of the flowchart shown in FIG. 6, but in this case, the rotor shaft inclination angle initial value α ₀ Instead, the work inclination angle initial value γ ₀ is used. Thus, in such an apparatus, the work inclination angle γ is calculated based on the amplitude W corresponding to the work cylindricity, and the holding mechanism mount 23 is configured to rotate until the work inclination angle γ is reached. ing.

Therefore, even in the second and third embodiments, the rotor shaft having the grindstone attached thereto is attached to the work.
On the other hand , the work is forcibly corrected in a direction in which the work cylindricity is relatively and geometrically reduced so that the work cylindricity is forcibly corrected, so that the grinding time required to reach a desired cylindricity can be reduced.

In the embodiment described above, the grindstone table is provided so as to be able to move back and forth in the axis X direction, and the headstock table is provided so as to be able to move back and forth in the axis Z direction. However, the present invention is not limited to this direction.

[0043]

The grinding machine according to the present invention, as described above,
Grinding force at the forward and backward ends of oscillation operation
Cylindricity measuring means for measuring the cylindricity of the work from the difference between
The cylinder of the current work obtained by this cylindricity measuring means
The amplitude of the grinding force corresponding to
Compare with the fixed value, and based on the difference,
Data axis relative to the workpiece and geometrically
Tilting means for tilting in the direction in which the cylindricity decreases
Of the oscillation operation (the grinding wheel
At the back of the work) and the reverse end (the grindstone is at the mouth of the work)
The difference (amplitude) of the grinding force at the position
Sensitively detects slight cylindricity deterioration of the work,
Rotor shaft with grinding wheel attached to workpiece
And tilted in the direction that the cylindricity of the work becomes smaller geometrically
Since the cylindricity of the work is forcibly corrected, the grinding time required to reach the desired work cylindricity can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a grinding machine according to the present invention.

FIG. 2 is a sectional view taken along line II-II shown in FIG.

FIG. 3 is an output waveform diagram of a grinding force signal.

FIG. 4 is an explanatory diagram illustrating a correlation between a grinding force signal amplitude and a cylindricity of a work.

FIG. 5 is an explanatory diagram illustrating a linear relationship between a grinding force signal amplitude and a work cylindricity;

FIG. 6 is a diagram illustrating a calculation processing operation of a rotor shaft inclination angle A.

FIG. 7 is an explanatory diagram for explaining a state of inclination of a grindstone.

FIG. 8 is a block diagram illustrating a grinding machine according to a second embodiment of the present invention.

FIG. 9 is a block diagram illustrating a third embodiment of the grinding machine according to the present invention.

[Explanation of symbols]

3 work 6 grindstone 16 cylindricity measurement unit 17 axis tilt angle detector 18 tilt angle setting unit S _F grinding force signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B24B 49/04 B24B 5/10 B24B 49/16

Claims (1)

(57) [Claims] 1. A grinding machine for oscillating a grindstone in an axial direction to grind an inner peripheral surface or an outer peripheral surface of a work, wherein a difference between a grinding force at a forward end and a backward end of the oscillation operation is a cylindricity of the work. Cylindricity measuring means for measuring the cylindricity of the current workpiece obtained by this cylindricity measuring means
The amplitude of the grinding force corresponding to the cylindricity and the preset vibration
Compare with the set width value and attach the grindstone based on the difference
An inclining means for inclining the rotor shaft relative to the workpiece and geometrically in a direction in which the cylindricity of the workpiece is reduced.