JPH0632899B2 - 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 in which an infinite number of abrasive grains are distributed on a rotating disk and rotating at high speed, the cutting per abrasive blade is further reduced and the force acting on the work is drastically reduced so that precision machining can be performed. 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 by 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. Precision grinding that superimposes ultrasonic vibrations and low frequency vibrations on a grinding wheel that is designed to cut chips finely by vibrating at a low frequency in a cutting direction that is perpendicular to the It is characterized by that.

(Examples) Various grinding methods according to the present invention will be described. A typical grinding method using a grinding wheel 18 that vibrates ultrasonically in the rotational axis direction and the radial direction will be described with reference to FIG. In the surface grinding, a grinding wheel 18 which vibrates ultrasonically in a radial direction and a rotation axis direction by a longitudinal ultrasonic vibrator is rotated at a grinding speed V in the directions of three arrows, and the headstock, that is, the grinding wheel or the work is driven by an electrohydraulic vibration drive device. Precise surface grinding is performed by vibrating the workpiece that moves in a straight line at a speed v by vibrating at a low frequency with a frequency F and an amplitude A in the cutting direction shown in the drawing. In the cylindrical grinding, as shown in FIG. 2, the grinding wheel 18 that vibrates ultrasonically in the radial direction and the rotation axis direction is ground at the grinding speed V and indicated by the arrow 3
Direction, the headstock, that is, the grinding wheel or the work is vibrated at a low frequency with the frequency F and the amplitude A in the cutting direction shown by the electrohydraulic vibration drive device, and the work is subjected to the speed v to perform precision cylindrical cutting. As shown in FIG. 3, the inner surface grinding is performed by rotating the grinding wheel 18 which is ultrasonically vibrated in the arrow direction 3 with the frequency f and the amplitude a _r in the radial direction and the frequency f and the amplitude a _s in the rotation axis direction as in the cylindrical grinding. Then, the headstock, that is, the grinding wheel or the work is vibrated at a low frequency with the frequency F and the amplitude A in the cutting direction shown in the drawing by the electrohydraulic vibration drive device, and the work 2 is rotated at the speed v to perform precision inner surface grinding.

Next, a grinding machine spindle vibration system and a grinding wheel shape for specifically carrying out the present invention will be described with reference to FIG.

The grinding wheel uses a taper hole or taper projection portion or a screw portion provided at the center of the grinding wheel, and can be attached and detached while being fitted to the spindle. The grindstone can be easily and quickly attached to and detached from the spindle, and ultrasonic vibrations can be efficiently transmitted to the grindstone without causing abnormal oscillation or abnormal heat generation at the mounting portion. A vertical ultrasonic vibrator 19 is provided at the tail of the main shaft 20, and an ultrasonic vibration grindstone is provided at the tip. The diameter and width of the grinding wheel, the diameter of the main shaft, and the length have a series of relationships, and by setting the width b to 20 mm, ultrasonic vibration is generated in the radial direction of the grinding wheel at the same time as the rotational axis direction, that is, the thickness direction of the grinding wheel. Can be made. Next, one embodiment of a grinding machine for carrying out the present invention will be described with reference to FIGS.

A 20 KHz vertical ultrasonic wave vibrator 19 is attached to the tail of the main shaft 20, and a rotary shaft and a radial ultrasonic vibration grindstone 21 are attached to the tip. Then, the sleeve 22 that straddles the two vibrating nodes generated in the main shaft is fixed to the position of the vibrating node by silver brazing, and the sleeve is supported by the two high precision rolling bearings 23 so that the main shaft can rotate with less friction. To do so. The rolling bearing is fixed in the housing to form the headstock 24 for the grinding machine. A pulley 25 and a slip ring 26 are attached to the sleeve 22. The blush is brought into contact with the slip ring with less friction. Blush and ultrasonic oscillator 27
Connect to the output terminal of. A three-phase induction motor 28 for rotating the spindle is attached to the spindle stock, that is, a grinding wheel, and a belt 29 transmits rotational power to the spindle. Then, the main shaft is rotated in the direction of arrow 30, and the grinding wheel is rotated at about 2000 / mmin. This headstock is fixed to a roller guide 33 provided on the reciprocating table 32 of the grinding machine bed 31 and capable of reciprocating movement in the feed direction 33 of the reciprocating table with less friction. The tail of the roller guide is connected by a connecting rod 34 to an electrohydraulic vibration drive 35 mounted on the carriage. Then, by operating the hydraulic unit 36 to supply the pressure oil and controlling it by the control device 37, the grinding wheel can be vibrated at a low frequency in the direction of the arrow 38. The work 39 is chucked by the chuck 40 of the grinder, one end of the work 39 is pushed by the tailstock 41, the work is rotated, and the feed speed S is applied to the carriage to perform the cylindrical grinding, whereby the frequency f = 20 KHz to 60 KHz. radial amplitude _{a r,} the rotation axis direction amplitude _{a s} together 5μm~20μm
Ultrasonic vibration with a frequency of about F = 20
Precision cylindrical vibration grinding is carried out by carrying out the present invention using a grindstone that vibrates at a low frequency of ˜200 Hz and vibration A = 0.02 to 0.2 mm. As the abrasive grains of the grinding wheel, all the currently used abrasive grains such as A abrasive grains, WA abrasive grains, GC abrasive grains, D abrasive grains and CBN abrasive grains can be used. The work shape 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 exhibits a epoch-making effect.

(Effect) The effect of the cylindrical grinding according to FIG. 5 will be described. Diamond grinding wheel # 200 using a 20 KHz vertical ultrasonic diffusive transducer, f = 20 KHz, a _r ≈8 μm, a _S ≈10
Ultrasonic vibration at μm, grinding speed 1200 / mmin, low frequency vibration F = 100Hz, vibration 0.2mm, low frequency vibration, ceramic (zirconia) round bar with diameter 10mm and length 150mm. By rotating at a speed of 8 m / min and giving a depth of cut of 0.1 mm to perform cylindrical grinding according to the present invention, a grinding force of about 1/2 to 1/5 that of conventional grinding is generated without generating abnormal grinding noise. , Surface roughness of 0.7 μmR _max without generating grinding heat without breaking the work,
It has become possible to efficiently grind with a roundness of 0.5 μm and a cylindricity of 2 μm per 120 mm, and a diameter of 2
According to the present invention, the surface of a soft rubber cylindrical surface having a length of 0 mm and a length of 300 mm is grinded by an excessive grinding force, and the straightness is eliminated by eliminating the defect that the end surface is dull and cannot be ground into a correct cylindrical surface.
We succeeded in improving the cylindricity and processing it into a correct cylindrical surface. These are all due to the effect of drastically reducing the grinding force, the effect of not generating grinding heat, and the synergistic effect, which are the features of the grinding method of the present invention.

[Brief description of drawings]

FIG. 1 is a surface grinding method when the present invention is carried out by an axial and radial ultrasonic vibrating grinding wheel, FIG. 2 is a cylindrical grinding method, FIG. 3 is a drawing explaining an inner surface grinding method, and FIG. The figure which shows an example of the shape dimension of a radial direction ultrasonic vibrating grinding wheel, an axial direction ultrasonic vibrating grinding wheel, an axial direction and a radial direction ultrasonic vibrating grinding wheel, and FIG. 5 is an example of the concrete Example of this invention. Is a top view of the cylindrical grinder and FIG. 6 is a side view thereof. 6 …… Pulse grinding force waveform 8 …… Intermittent pulse grinding force waveform 10 …… Low frequency vibration 11 …… Low frequency vibration Grinding wheel 14 …… Axial ultrasonic vibration 15 …… Axial ultrasonic vibration Grinding wheel 16 …… Radial ultrasonic vibration 17 …… Radial ultrasonic vibration grinding wheel 18 …… Axial and radial ultrasonic vibration grinding wheel 19 …… Vertical ultrasonic vibrator 27 …… Ultrasonic oscillator 36,37 …… Electric, Hydraulic vibration drive 47 ... axial and radial ultrasonic vibrations

Claims (1)

[Claims] 1. A grindstone wheel rotating at high speed is ultrasonically vibrated in the rotational axis direction and the radial direction of the grindstone wheel, and further, the grindstone wheel or the workpiece is in a direction perpendicular to the rotational axis direction of the grindstone wheel, and A precision compound grinding method that superimposes ultrasonic vibrations and low frequency vibrations on a grinding wheel that is designed to finely cut chips by vibrating at low frequencies in the cutting direction perpendicular to the machined surface.