JPH0626790B2 - Precision compound grinding method that superimposes ultrasonic vibration and low frequency vibration on grinding wheel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides a grindstone that superimposes ultrasonic vibrations and low-frequency vibrations, which makes it easy to precisely grind rubber, ceramics, etc., which are difficult with conventional grinding methods. The present invention relates to a precision compound grinding method using a car.

(Prior Art) In order to perform precision processing with a cutting / grinding tool, it is necessary to perform processing by a method that reduces the force applied to the work even a little. The cutting force is reduced by, for example, rotating a milling cutter, which has a finite number of cutting blades on a rotating disk, at high speed to perform cutting. By rotating a grinding wheel with innumerable abrasive grains distributed on a rotating disk at high speed to perform grinding, the cutting depth per blade of the abrasive grains is further reduced, and the force acting on the workpiece is drastically reduced, enabling precision machining. become. However, on the other hand, about 20
It is also well known that the average grinding temperature rises so much that the work and the grinding wheel must be cooled by a large amount of grinding fluid for high speed grinding up to 00 m / min. Accompanying the high speed rotation of the grinding wheel. In spite of this remarkable heat generation phenomenon, the effect of drastically reducing the force acting on the work is so great that grinding with a grinding wheel is widely used at present. Conventionally, the material of the work is mainly metal, but the heat transfer efficiency is good and the cooling effect is good. Therefore, precise grinding is possible by using a large amount of an appropriate grinding fluid.

(Problems to be solved by the invention) However, today, new materials have been developed regardless of the existence of precision processing theory and technology, and among them, rubber,
It contains many new materials with poor heat transfer efficiency, such as FRP and ceramics. Further, extremely high processing accuracy is required for these as well.

In order to meet the expectations of precision machining for these, a grinding method is required which can further reduce the average grinding temperature rise and drastically reduce the grinding force. There is a problem that there is no precision grinding method common to soft and sticky materials such as rubber and hard and brittle materials such as metals and ceramics.

(Means for Solving the Problems) In the present invention, a grinding wheel that rotates at a high speed is ultrasonically vibrated in the rotation axis direction and / or the radial direction of the grinding wheel, and the work is further oriented in a direction perpendicular to the rotation axis of the grinding wheel. In addition, by vibrating at a low frequency in the work feed direction, which is a direction along the work machining surface, and intermittently contacting the grinding wheel, an intermittent pulse grinding force waveform is generated to finely cut chips. It is characterized by.

(Example) An ultrasonic vibration grindstone used in the present invention will be described with reference to Figs. FIG. 1 is a view showing a grinder spindle and a grinding wheel vibrating system in which a longitudinal ultrasonic transducer 23 is provided at the tail of a spindle 24 and a grinding wheel 19 is provided at the tip. When the natural frequency of the longitudinal ultrasonic transducer is 20 KHz, there is a series of relationships between the diameter and width of the grinding wheel and the diameter and length of the spindle. For example, if the diameter of the spindle is 50 mm, the length is 1 /
130mm for 2 wavelengths, 165mm diameter for grinding wheel,
The width is 10 mm. With such a shape and dimensions, the grinding wheel can be ultrasonically vibrated only in the radial direction to form the radial ultrasonic vibration grinding wheel 19.

This grinding wheel can be attached to and removed from the spindle by taper coupling using a tapered hole on the grinding wheel or spindle, by screw coupling with female and male threads, or by bolting, to reliably transmit ultrasonic vibrations. be able to.

FIG. 2 is a diagram for explaining a composite ultrasonic vibration grinding wheel in the rotational axis direction and in the radial direction. As shown, the width of the grinding wheel is set to 20 mm, and the other geometrical dimensions are the same as those in FIG. 1, so that the grinding wheel has ultrasonic frequency f, amplitude a _s , and amplitude a _r in the rotational axis direction and the radial direction. The ultrasonic wave vibrating grinding wheel 14 can be a superposed ultrasonic vibrating grinding wheel in the direction of the rotation axis and in the radial direction. For a grinding wheel with a small diameter, a longitudinal vibration system is used for the ultrasonic vibration grinding wheel in the rotation axis direction.

FIG. 3 is a view for explaining a rotary axis direction ultrasonic vibration grinding wheel. As shown in the figure, the width of the grinding wheel is set to 10 mm, and the other geometrical dimensions are the same as those in FIG. 1, so that the grinding wheel is rotated only in the rotational axis direction with ultrasonic frequency f = 20 KHz and amplitude a.
_The rotation axis direction ultrasonic vibration grinding wheel 21 that ultrasonically vibrates at _{s 2} = 7 μm can be used.

Next, various grinding methods according to the present invention using this grinding wheel will be described. A typical grinding method using the rotary vibration ultrasonic wheel 14 will be described with reference to FIG. Surface grinding
The grindstone 14 is rotated at the grinding speed V in the direction of the arrow, and the work 2
Further, the work is moved linearly while being vibrated at a low frequency by the stepping motor and is fed at the processing feed speed v, and the surface is ground by the intermittent pulse grinding force waveform obtained by intermittently contacting the grinding wheel. The direction of low-frequency vibration is the machining feed direction, which is perpendicular to the rotation axis of the grinding wheel and parallel to the workpiece machining surface. Cylindrical grinding works 2
5 is rotated at a peripheral speed v while vibrating at a low frequency with a frequency F and an amplitude A by a stepping motor, and the grinding wheel 14 is rotated at a grinding speed V in the direction of the arrow to perform cylindrical grinding. In the inner surface grinding, similarly to the cylindrical grinding, the work 26 is oscillated at a peripheral speed v while vibrating the work 26 at a low frequency with a frequency F and an amplitude A by a stepping motor, and the grinding wheel 14 is rotated at a high speed in the arrow direction at the grinding speed V. Internal grinding. In addition to this, the present invention using the vertical vibration system axial vibration grindstone having a small diameter is also applied to the processing of grooves.

A typical grinding method using the radial ultrasonic vibration grinding wheel 19 will be described with reference to FIG. In the surface grinding, the grinding wheel 19 is rotated in the direction of the arrow at the grinding speed V, the work 2 is moved linearly while vibrating the work at a low frequency by the stepping motor, and is fed at the feeding speed v, and intermittently brought into contact with the grinding wheel 19. Surface grinding is performed by the intermittent pulse grinding force waveform obtained as described above. In the cylindrical grinding, the peripheral speed v is obtained by vibrating the work 25 at a low frequency with a frequency F and an amplitude A by a stepping motor.
And the grinding wheel 19 is rotated in the direction of the arrow at a grinding speed V to perform cylindrical grinding. In the inner surface grinding, as in the case of the cylindrical grinding, the work 26 is rotated at a peripheral speed v while vibrating the work 26 at a low frequency with a frequency F and an amplitude A by a stepping motor to rotate the grinding wheel 19 at a grinding speed V in the direction of the arrow to perform the inner surface grinding. To do. A grinding wheel with a small diameter for small diameter holes can be manufactured by increasing the frequency.

A typical grinding method using the ultrasonic vibration grindstone 21 in the rotational axis direction and the radial direction will be described with reference to FIG. In the surface grinding, the grinding wheel 21 is rotated in the direction of the arrow at a grinding speed V of about 2000 m / min, and the work 2 is moved linearly while vibrating the work at a low frequency by a stepping motor and sent at the feed speed v, and intermittently. Surface grinding is performed by an intermittent pulse grinding force waveform obtained by contacting the grinding wheel 21. In the cylindrical grinding, the work 25 is rotated at a peripheral speed v while vibrating the work 25 at a low frequency with a frequency F and an amplitude A by a stepping motor to rotate the grinding wheel 21 at a grinding speed V in the arrow direction to perform cylindrical grinding. In the inner surface grinding, as in the case of the cylindrical grinding, the work 26 is rotated at a peripheral speed v while vibrating the work 26 at a low frequency with a frequency F and an amplitude A by a stepping motor, and the grinding wheel 21 is rotated in a direction of an arrow at a grinding speed V to form an inner surface. Grind. A grinding wheel with a small diameter for small diameter holes can be manufactured by increasing the frequency.

Next, an embodiment of the present invention showing a concrete grinder will be described.
The vibrating cylindrical grinding machine will be described with reference to FIGS. 7 and 8.

A 20 KHz vertical ultrasonic diffusive vibrator 27 is provided at the tail of the main shaft 24, and at the tip end thereof is a rotary ultrasonic wave vibrating grinding wheel 2
Attach 1. Then, a sleeve 28 that straddles two vibrating nodes generated on the main shaft is fixed to the vibrating node position by silver brazing, and the sleeve is fixed to two high precision rolling bearings 29.
Supported by so that the main shaft can rotate with less friction. The rolling bearing 29 is fixed in a housing 31 and constitutes a headstock 32 for a grinder. A pulley 30 is attached to the sleeve 28, and a slip ring 33 is attached to the pulley 30. The brush 35 is brought into contact with the slip ring 33 with less friction. Brush 35 and ultrasonic oscillator 36
Connect to the output terminal of. A three-phase induction motor 37 for rotating the spindle is attached to the spindle stock 32, and rotational power is transmitted to the spindle 24 by a belt 38. Then, the spindle 24 is rotated in the direction of arrow 3 to rotate the grinding wheel. This headstock is attached to the grinding machine carriage 38. The work 2 is attached to the chuck 39 of the grinder, and the other end is supported by the center 40. The work is rotated at a speed V of maximum 200 rpm by a low frequency vibration with a frequency F = maximum 120 Hz and an amplitude A = maximum 0.2 mm by an electric stepping motor driven by a controller and a power unit 41. By sending the carriage 38 to the work at the feed speed S in the direction of the arrow 42, the frequency f = 20K.
Hz to 60 KHz, radial amplitude a _r , rotation axis direction amplitude a _s
Precision vibration cylindrical grinding is carried out by superimposing ultrasonic vibrations of about 5 μm to 20 μm, and by carrying out the present invention using a composite ultrasonic vibration grindstone. Abrasive grains of a grinding wheel are A abrasive grains, WA abrasive grains,
All currently used abrasive grains such as GC abrasive grains, D abrasive grains, and CBN abrasive grains can be used. As a work material, it is applied to all non-metal industrial materials such as ferrous metal, non-ferrous metal and rubber, and all industrial materials such as ceramics and exerts a epoch-making effect.

Next, the vibrating surface grinder will be described with reference to FIG. Table 43 that reciprocates the surface grinder bed 42
A low-frequency vibration table 4 supported by steel balls on the top and capable of linear movement in the reciprocating direction of the table with little friction.
4 is provided, and one end thereof is fixed to the electro-hydraulic vibration drive device 45 also fixed on the table 43 via a connecting rod. This electro-hydraulic vibration drive device is vibration driven by the hydraulic pump unit 46 and the control device 47. Then, for example, a low frequency vibration can be performed with a frequency F = 100 Hz and an amplitude A = 0.2 mm.

On grinding machine column 51, the amplitude a _s in the rotation axis direction of the arrow 14 when the vibrating cylindrical grinder as well as 20KHz longitudinal ultrasonic transducer 27 and the spindle 24 and the frequency _f, the radial direction of arrow 18 A headstock 50 for a vibrating surface grinder, which is composed of a grindstone 21 that vibrates ultrasonically with an amplitude a _r , is fixed. Then, the main shaft is rotated by the belt 49 in the direction of arrow 3 using a three-phase induction motor, and the grinding speed is set to about 2000 m / min.

The slip ring 33 is attached to the spindle, and brush 3
The excitation voltage from the ultrasonic oscillator 36 is applied to the rotating oscillator via 5. Covers 48 and 52 are attached to the rotating oscillator 27 and the grinding wheel to ensure safety.

In this way, the grinding wheel 21 having the shape and dimensions shown in FIG.
With the same frequency f = 20 KHz and an amplitude a _r ≈8 μ in the radial direction.
Precision vibration surface grinding according to the present invention is carried out by ultrasonically vibrating with amplitude m _s ≉10 μm in the axial direction and at the same time smoothly rotating at a high speed, and feeding low-frequency vibration to the work surface to perform feed surface grinding.

In the case of this surface grinding as well, like the cylindrical grinding, the present invention is applied to all kinds of abrasive grains and workpieces, and particularly to a workpiece such as rubber or ceramics which cannot be improved in grindability by simply rotating at high speed. And exhibits an epoch-making precision surface grinding effect.

(Effects) Specific effects of implementing the present invention will be described. The cylindrical grinding according to FIG. 7 will be described. The diamond grindstone # 200 having the shape and dimensions shown in FIG. 3 was used for f = 20 KHz, a _r ≈8 μm, a _s using a 20 KHz vertical ultrasonic diffusive vibrator.
Grinding speed V = 800m / m with ultrasonic vibration at ≒ 10μm
As in, a silicon nitride round bar having a diameter of 10 mm and a length of 100 mm is controlled by P _F 11 pulse, P _R 6 pulse, P _B 1 pulse and P _R 5 pulse to vibrate at a low frequency with F = 90 Hz and V = By rotating at a speed of 1.5 m / min and setting a cutting length per cycle of vibration of the work of 0.25 mm to give a depth of cut of 10 μm and performing the vibration cylindrical grinding according to the present invention, no abnormal grinding noise is generated.
Surface roughness of 0.3 μmR with extremely little grinding resistance without extending the tool life and breaking the work without causing instantaneous abnormal heat generation such as spark generation near the grinding point.
max, roundness 0.5 μm, cylindricity 1 μm per 100 mm
Succeeded in the precision circular cylinder processing.

In the surface grinding shown in FIG. 9, the diamond grindstone # 200 having the shape and dimensions shown in FIG. 3 was used for f = 20 KHz and a _r ≈8 μ using a 20 KHz vertical ultrasonic diffusive vibrator.
m, is ultrasonically vibrated in _{a s} ≒ _10μm, grinding velocity V = 8
Frequency of F at the end surface of rubber product with a diameter of 4 mm at 00 m / min
= 100 Hz, amplitude A = 0.2 mm, low-frequency vibration is applied, a depth of cut is 0.1 mm, and the feed rate is v = 200 mm / min.
A flatness of 0 was successfully achieved for a material that was 15 μm inward and was not flat.

The above description has been made on the grinder in which the low frequency vibration is applied to the workpiece, but it goes without saying that the same result can be obtained even when the low frequency vibration is applied to the grinding wheel.

[Brief description of drawings]

FIG. 1 is a front view of an example of the shape and dimensions of a radial ultrasonic vibrating grindstone, FIG. 2 is a front view of an example of the shape and dimension of a rotating axis direction ultrasonic vibrating grindstone, and FIG. Of the direction and shape of the directional ultrasonic vibration grindstone Front view, FIG. 4 is an explanatory view of a surface grinding method, a cylindrical grinding method, an inner surface grinding method when the present invention is carried out by the rotary axis direction ultrasonic vibration grinding stone, FIG. 5 is an explanatory view of a surface grinding method, a cylindrical grinding method and an inner surface grinding method when the present invention is carried out by a radial ultrasonic vibration grinding wheel, and FIG. 6 is a rotary axis direction, a radial ultrasonic vibration grinding wheel of the present invention. FIG. 7 is an explanatory view of a surface grinding method, a cylindrical grinding method, and an inner surface grinding method when carrying out the embodiment, FIG. 7 is a plan view of an embodiment of a cylindrical grinding machine for carrying out the present invention, FIG. 8 is a side view of the same, and FIG. It is a front view of an embodiment of a surface grinder for carrying out the present invention. 14 ... Rotation axis ultrasonic vibration grinding wheel 19 ... Radial ultrasonic vibration grinding wheel 21 ... Rotation axis and radial ultrasonic vibration grinding wheel 27 ... Vertical ultrasonic vibrator 36 ... Ultra Sound wave oscillator 40 ... Pulse motor 44 ... Low frequency vibration table 46,47 ... Electro-hydraulic vibration drive device

Claims (1)

[Claims] 1. A high-speed rotating grinding wheel is ultrasonically vibrated in the rotational axis direction and / or in the radial direction of the grinding wheel, and the work is further oriented in a direction perpendicular to the rotation axis of the grinding wheel and along the work surface. Vibration of the grinding wheel, which is made to cut the chips finely by vibrating it at a low frequency in the workpiece machining feed direction and intermittently contacting the grinding wheel to generate an intermittent pulse grinding force waveform. Precision compound grinding method with superposed vibration.