JPH0626789B2 - Precision compound grinding method that superimposes ultrasonic vibration and low frequency vibration on grinding wheel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention superimposes ultrasonic vibrations and low frequency vibrations on a grinding wheel that can easily precisely grind rubber, ceramics, etc., which have been difficult with conventional grinding methods. The present invention relates to a precision compound grinding method for performing grinding by grinding.

(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 as much as possible. 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 2
It is already well known that the average grinding temperature rises so much that the workpiece and the grinding wheel must be cooled with a large amount of grinding fluid for high speed grinding up to 000 m / min. Despite the remarkable heat generation phenomenon that accompanies the high speed rotation of the grinding wheel, the grinding effect by the grinding wheel is widely used at present because the effect of drastically reducing the force acting on the work is great. Conventionally, the material of the work is mainly metal, and the heat transfer efficiency is good and the cooling effect is good even if heat is generated, so that precise grinding can be performed 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 Problems) According to the present invention, a grinding wheel that rotates at high speed is ultrasonically vibrated in a rotation axis direction and a radial direction of the grinding wheel, and further, the grinding wheel or the work is rotated in a rotation axis direction of the grinding wheel. It is characterized in that the chips are finely shredded by vibrating at low frequency.

(Embodiment) Therefore, a new grinding method was considered in which the above-mentioned characteristics can be utilized without reducing the grinding efficiency.

Next, one example of a grinding machine spindle vibration system and a grinding wheel shape for carrying out the method of the present invention will be described.

FIG. 1 shows that a longitudinal ultrasonic transducer 39 is provided at the tail of the main shaft 41,
FIG. 3 is a diagram showing a grinder spindle and a grinding wheel vibrating system for carrying out the present invention, in which a vibrating grindstone 40 that vibrates ultrasonically in the radial direction and the rotating shaft direction is provided at the tip.

When the natural frequency of the longitudinal ultrasonic transducer 39 is 20 KHz, the diameter of the main shaft is 50 mm, and its length is 1 wavelength.
By setting the diameter of the grinding wheel to 0 mm, the diameter of the grinding wheel to 165 mm, and the width to 10 mm, it is possible to ultrasonically vibrate the grinding wheel at the frequency of 20 KHz in the radial direction and the rotational axis direction at the same time. Further, the grinding wheel is vibrated at a low frequency in the rotation axis direction.

Next, various grinding methods according to the present invention using this grinding wheel will be described. For surface grinding, as shown in FIG. 2, a vibrating grindstone 40 that ultrasonically vibrates in a radial direction and a rotation axis direction by a vertical ultrasonic vibrator is rotated in a direction of an arrow 3 at a grinding speed V of about 2000 m / min, and its main shaft is rotated. A table, that is, a grinding wheel is vibrated at a low frequency with a vibration frequency F and an amplitude A in a rotation axis direction by an electrohydraulic vibration drive device, and a peripheral speed v is given to a workpiece that moves in a straight line to perform precision surface grinding. For cylindrical grinding, as shown in FIG. 3, about 20 vibration grindstones 40 that vibrate ultrasonically in the radial direction and the rotation axis direction are used.
Rotate in the direction of arrow 3 at a grinding speed V of about 00 m / min,
The headstock, that is, the grinding wheel is vibrated at a low frequency with a frequency F and an amplitude A in the rotation axis direction by an electrohydraulic vibration drive device, and a peripheral speed v is applied to the work to perform precision cylindrical grinding. As shown in FIG. 4, inner surface grinding is performed in the radial direction with frequency f and amplitude a as in cylindrical grinding.
_r, axially frequency f, the amplitude a _s, a grinding wheel 28 of the ultrasonic vibration to the approximately 2000 m / min to the target is rotated at high speed in the direction of the arrow 3, electro-hydraulic vibration driving the headstock i.e. grinding wheel The device is vibrated at a low frequency with a frequency F and an amplitude A in the rotation axis direction, and the work 2 is rotated at a peripheral speed v to perform precision inner surface grinding.

Next, the vibrating cylindrical grinder 87 will be described with reference to FIGS. 5 and 6.

A 20 KHz vertical ultrasonic wave vibrator 39 is attached to the tail of the main shaft 41, and a rotary shaft and a radial ultrasonic vibrating grindstone 40 are attached to the tip. Then, a sleeve 42 straddling two vibrating nodes generated on the main shaft is fixed by silver brazing at the position of the vibrating node, and the sleeve is supported by two high precision rolling bearings 43 to rotate the main shaft 41 with less friction. It can be so. The rolling bearing 43 is fixed in the housing, and the headstock 4 for the grinder is used.
Make up 4. A pulley 45 and a slip ring 46 are attached to the sleeve 42. The brush 50 is brought into contact with the slip ring 46 with less friction. Brush 5
0 and the output terminal of the ultrasonic oscillator 47 are connected. A three-phase induction motor 49 for driving the spindle to rotate is attached to the spindle stock 44, and rotational power is transmitted to the spindle 41 by a belt 48. Then, rotate the spindle in the direction of arrow 64,
Rotate at 0m / min. This headstock, that is, a grinding wheel, is provided on the reciprocating table 61 on the grinding machine bed 62. The roller guide 5 which can reciprocate in the feeding direction 63 of the reciprocating table 61 with little friction.
Fix to 2. The tail of the roller guide is connected by a connecting rod 53 to an electrohydraulic vibration drive 54 mounted on the carriage. Then, the hydraulic unit 56 is operated to supply the pressure oil, and the control device 55 controls the vibration grindstone 40 so that the vibration frequency F and the amplitude A are, for example, F in the direction of the arrow 65.
= 100Hz, A = 0.2mm, low frequency vibration. The work 59 is chucked to the chuck 60 of the grinder, one end of the work 59 is pushed by the tailstock 66, the work is rotated, and the feed speed S is applied to the carriage to perform cylindrical grinding.
= 20 KHz to 60 KHz, the radial direction amplitude a _r 58, and the rotating shaft direction amplitude a _s 57 are ultrasonically vibrated at about 5 μm to 20 μm, and the vibration frequency F is 20 to 200 Hz in the rotating shaft direction.
Precision cylindrical vibration grinding is performed with a grindstone that vibrates at a low frequency with an amplitude A of 0.02 to 0.2 mm.

The work may be vibrated instead of the grinding wheel.

(Effects) Next, specific effects of the present invention will be described. Diamond grinding wheel # 20 having the shape and dimensions shown in FIG.
F = 20K using a 20KHz vertical ultrasonic diffractor
Hz, _{a r} ≒ 8 [mu] m, is ultrasonically vibrated in the spindle rotational axis direction and radial direction in _{a s} ≒ 10 [mu] m, as a grinding speed of 1200 m / min, the low-frequency frequency F = 100 Hz this, amplitude 0.2mm
Using a low-frequency vibration in the direction of the main shaft rotation, a ceramic (zirconia) round bar with a diameter of 8 mm and a length of 120 mm is rotated at a peripheral speed of 10
By rotating at a speed of m / min to give a depth of cut of 10 μm and performing cylindrical grinding according to the present invention, an abnormal grinding noise is not generated, and the work is ground with a grinding force of about 1/3 to 1/5 that of conventional grinding. Surface roughness 0.2μmRmax, roundness 0.5μm, cylindricity 120m without generating grinding heat without breaking.
It has become possible to perform highly accurate and efficient precision grinding with a high precision of 1 μm per m. Further, by performing precision grinding according to the present invention on the surface of a soft rubber cylindrical surface having a diameter of 20 mm and a length of 300 mm, the disadvantage that the conventional grinding cannot sacrifice the end surface due to the excessive grinding force to the correct cylindrical surface can be solved. The straightness and cylindricity have been improved to near zero, and we have succeeded in realizing ultra-precision cylindrical machining. All of these are due to the synergistic effects of the effect of drastically reducing the grinding force, the effect of not generating grinding heat, and the effect of smoothing the finished surface, which are the features of the grinding method of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of an embodiment of an axial and radial ultrasonic vibrating grindstone used in the present invention, and FIG. 2 is a case where the present invention is embodied by an axial radial radial vibrating grindstone. Surface grinding method, FIG. 3 is an explanatory view showing the same cylindrical grinding method, FIG. 4 is an explanatory drawing showing the same inner surface grinding method, FIG. 5 is a plan view of an embodiment of a cylindrical grinding machine for carrying out the present invention, and FIG. It is the same side view. 2 ... Work 39 ... Vertical ultrasonic transducer 40 ... Vibration whetstone 41 ... Spindle 47 ... Ultrasonic oscillator 54 ... Electrohydraulic vibration drive device

Claims (1)

[Claims] 1. A grinding wheel that rotates at a high speed is ultrasonically vibrated in the rotational axis direction and in the radial direction of the grinding wheel, and the grinding wheel or work is further vibrated at a low frequency in the rotational axis direction of the grinding wheel to remove chips. A precision compound grinding method that superimposes ultrasonic vibrations and low-frequency vibrations on a grinding wheel that is cut into minute pieces.