JPH028867B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a centripetal shim for a grinding wheel in which a hard abrasive grain layer is provided on the outer peripheral surface of a ceramic or resin holder.

An object of the present invention is to eliminate vibration of the outer circumferential surface of a hard abrasive grain layer when the grinding wheel is mounted on a grindstone sleeve.

Such grinding wheels are made of porous ceramics similar to vitrified grinding wheels or resin holders made of resinoid grinding wheels, and hard abrasive grains such as diamond or cubic boron nitride are bonded with a synthetic resin binder or a vitrified binder on the outer circumferential surface of a resin holder made of porous ceramics similar to vitrified whetstones. When this hard abrasive grain layer is attached to the grinding wheel shaft of an upper grinding machine that is attached to a grinding wheel sleeve, the outer diameter of the abrasive grain layer fluctuates considerably due to the fitting clearance with the grinding wheel sleeve. . The hard abrasive grains are very expensive, and it is preferable to minimize the amount of correction to remove runout.

However, in order to reduce vibration when installing the grindstone sleeve, it is sufficient to reduce the fitting clearance with the grindstone sleeve, but if the holder is made of ceramics or resin, unlike a metal holder, precise inner diameter machining is required. Not only was this impossible, but the grindstone sleeve (made of iron) had a larger thermal expansion than the ceramic holder, so a certain amount of clearance was required.

Therefore, when the grinding wheel is attached to the grinding wheel sleeve, a relatively large runout occurs depending on the fitting clearance. In order to eliminate this runout, expensive abrasive grains had to be scraped off with a diamond wheel, which was not only uneconomical but also required a long time to correct the runout before grinding.

The present invention aims to solve such problems by forming a centripetal shim on the circumferential surface of the holder that has an elastic force that reduces the fitting clearance with the grindstone sleeve and absorbs the thermal expansion of the grindstone sleeve. This provides a suitable method. Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 10 denotes a grinding wheel formed by the method of the invention, which includes a holder 11 made of porous ceramics similar to a vitrified grinding wheel or a resinoid grinding wheel similar, and a layered material on the outer peripheral surface of this holder 11. A hard abrasive layer 12 formed by bonding hard abrasive grains such as diamond or cubic boron nitride with a synthetic resin binder or a vitrified binder, and a centripetal layer 12 provided on the inner peripheral surface of the center hole 13 of the holder 11. It is composed of a shim 14. This grinding wheel 10 is the second
As shown in the figure, when attached to the grindstone sleeve 20, the centripetal shim 1 is attached to the outer peripheral surface 20a of the fitting part.
4 abut against each other and are centered with respect to the whetstone sleeve 20, and the flange member 21 and the whetstone sleeve 20
It is clamped and held by the flange portion 20b that is integrated with the flange portion 20b.
Due to the action of the centripetal shim 14, even when the grinding wheel 10 is newly attached to the grinding wheel sleeve 20, the outer diameter deviation of the hard abrasive grain layer 12 can be suppressed to a minimum. As a result, the amount of correction of the runout of the grinding wheel is reduced, and expensive hard abrasive grains can be used effectively, and the time required for correction of the grinding wheel is also significantly reduced.

Next, a method of forming the centripetal shim 14 will be explained. In FIG. 3, a grinding wheel sleeve 20 or similar mold member 25 is supported rotatably in a horizontal plane. The mold member 25 has a grindstone sleeve 2
A reference surface 26 for forming a shim that has the same outer diameter as the fitting portion 20a of No. 0 and is concentric with the center of rotation.
is provided. The axial height h of this reference surface 26 is smaller than the width b of the grinding wheel 10,
A protrusion 27 is provided on the end face to prevent the silicone rubber from flowing. The reference surface 26 of the mold member 25 and the center hole 13 of the grinding wheel 10 are fitted together. The inner diameter of the center hole 13 is comfortably larger than the outer diameter of the reference surface 26, so that a clearance of about 0.2 mm in radius is formed. This clearance is set so that it is almost uniform in the circumferential direction, and the dial indicator 28 is set so that it is approximately uniform in the circumferential direction.
While rotating the mold member 25 in contact with the outer circumferential surface of the grinding wheel 10, the grinding wheel 10 is centered using an adjustment screw 29 provided on the periphery of the mold member 25 so that the outer diameter runout is minimized. After centering, silicone rubber (two-component RTV rubber) is poured into the clearance between the reference surface 26 and the center hole 13 at several locations on the circumference. Such silicone rubber has a viscosity of 200 voids at 25°C,
If it is poured to an extent that it does not overflow from the front protrusion 27, it will penetrate into narrow gaps due to the action of gravity. If left as is for one day and night, the silicone rubber will harden and can be removed from the mold member 25. 3~ for complete hardening
It takes four days to harden to a hardness of about 45.

Before pouring the silicone rubber, the reference surface 2
Silicone grease was applied as a mold release agent to the 6 side, and the inner peripheral surface of the grinding wheel was cleaned and oil was removed, and then surface treated with Primer T (commercially available from Shin-Etsu Chemical) as a pre-adhesion treatment agent. put.

After taking out the silicone rubber from the mold member 25, the excess portion of the silicone rubber, that is, the portion other than the portion that has flowed between the reference surface 26 and the inner peripheral surface of the center hole 13, is cut off and removed.

Since the centripetal shim 14 formed in this manner is made of rubber even after hardening, it has appropriate elasticity, and can absorb changes in clearance due to thermal expansion of the grinding wheel sleeve 20, so that the inner peripheral surface of the holder It is possible to prevent the generation of stress that would cause cracks in the structure.

Furthermore, due to the centering action of the centripetal shim 14, the run-out of the grinding wheel when the grinding wheel sleeve is attached can be made very small, and the amount of adjustment of the grinding wheel is reduced, which has the advantage of being economical and shortening the adjustment time. .

Although the centripetal shims in the above embodiment were attached to the inner peripheral surface of the center hole at several locations, the present invention is not limited to this, and shims continuous in the circumferential direction are also effective.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, in which FIG. 1 is a front view of a grinding wheel formed by the method of the present invention, FIG. 2 is a longitudinal cross-sectional view of the grinding wheel with the sleeve inserted, and FIG. FIG. 2 is a diagram showing a shim formation state. 10... Grinding wheel, 11... Holder, 12...
Hard abrasive grain layer, 14... Centripetal shim, 20... Grindstone sleeve, 21... Flange, 25... Mold member.

Claims (1)

[Claims] 1 Hard abrasive grains such as diamond or cubic boron nitride are bonded to the outer peripheral surface of a porous ceramic holder made of a vitrified whetstone analogue or a resin holder made of a resinoid whetstone analogue using a synthetic resin binder or a vitrifyide binder. A method for forming a centripetal shim for a grinding wheel having a hard abrasive grain layer, the shim being rotatably supported in a horizontal plane, having the same outer diameter as the fitting part of the grinding wheel sleeve, and forming a concentric circle with respect to the center of rotation. The grinding wheel is placed almost concentrically on a mold member on which a forming reference surface is formed, and the mold member is rotated while the dial indicator is in contact with the outer peripheral surface of the hard abrasive grain layer, so that outer diameter runout is minimized. A method for forming a centripetal shim for a grinding wheel, in which the grinding wheel is centered, and after centering, silicone rubber is poured into the clearance between the reference surface and the center hole, and after hardening, it is cut out from the mold member.