JP2001062735A - Rotary grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the remarkable improvement of grinding/polishing performance compatible with the superior finishing of a surface to be polished, and to elongate the life by solidifying the woven fabric including inorganic compound fiber by a resin or the like, forming the same into the cylindrical shape, and providing an axial one end surface of the cylindrical member with a grinding and polishing working surface. SOLUTION: The rotary grinding wheel S is formed by laminating band- shaped woven sheets composed of inorganic compound fiber several times, and adhering them by a resin or the like to form a cylindrical member 1. One end surface 1a in the axial X direction of the cylindrical member 1 is dressed to form a grinding and polishing working surface on its approximately whole surface. The other end part in the axial X-direction of the cylindrical member 1 is fixed to the approximately disc-shaped holders 2, 3, and mounted on a grinding disc through the holders 2, 3. This rotary grinding wheel S is rotated while pressing the working surface shown as an upper edge in a drawing, to a surface to be ground and polished for the machining of an outer race of a bearing or the like, to grind and polish the surface with high accuracy, and the working life can be sufficiently elongated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a rotary grindstone used for grinding and polishing a surface of a workpiece by rotating the workpiece while pressing the surface.

[0002]

2. Description of the Related Art Conventionally, as this kind of rotary grindstone,
Vitrified whetstones in which abrasive grains are combined with a compound such as feldspar and viscosity, and resinoid whetstones in which abrasive grains are combined with a resin compound are generally used.

[0003] Further, as disclosed in Japanese Patent Publication No. 59-1557, for example, it has also been proposed to form a grindstone by further mixing abrasive grains with a fiber in which abrasive grains are kneaded and mixing, and solidifying the resultant with a resin compound. Have been.

[0004]

However, in a grindstone mixed with abrasive grains as in each of the above-mentioned conventional examples, if the abrasive grains are enlarged to improve the grinding / polishing performance, the surface to be polished becomes rough. If the grain size of the abrasive grains is made smaller, the surface roughness becomes smaller and a smooth finish can be obtained, but the polishing performance becomes lower as the grain size of the abrasive grains becomes smaller. That is, it was not possible to simultaneously improve the polishing performance and achieve a good finish of the polished surface.

[0005] Further, the abrasive stone mixed with abrasive grains has a disadvantage that when worn, the abrasive grains fall off during use, and the contribution of the abrasive grains to the grinding and polishing cannot be sufficiently increased. In particular, when the abrasive grains are hardened with a binder, there is a problem that if the elasticity of the binder is low, the abrasive grains are easily broken, and the compatibility with the workpiece is deteriorated, and polishing unevenness is likely to occur. On the other hand, when a highly elastic resin compound such as polyurethane is used as the binder, the wear life is shortened as a whole, and unevenness is generated on the used surface of the grindstone, thereby shortening the service life.

The above-mentioned proposal example (Japanese Patent Publication No. 59-1557)
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, when a grindstone is composed of fibers, abrasive grains, and a resin compound in which abrasive grains are kneaded and mixed, although the elasticity and the grinding / polishing performance can be improved to some extent, the grinding / polishing performance that depends on the abrasive grains is improved. The degree of improvement cannot be said to be sufficient, and it is inevitable that the service life is shortened similarly to the grindstone obtained by solidifying the abrasive grains with a resin compound.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to improve the grinding and polishing performance and improve the quality of the surface to be polished by devising the structure of the rotary grindstone. And to extend the service life thereof.

[0008]

In order to achieve the above object, in the present invention, a woven fabric containing inorganic compound fibers is solidified with a resin or the like to form a cylindrical shape, and one end surface in the axial direction is ground and polished. Use surface was provided.

Specifically, the rotary grinding wheel according to the first aspect of the present invention
A rotating grindstone provided with a use surface for grinding and polishing on one axial end surface of a cylindrical portion, wherein the cylindrical portion is formed of a woven fabric in which at least one of a warp or a weft is made of an inorganic compound fiber. The warp and the weft of the woven fabric are solidified by either resin or an inorganic adhesive compound and are bonded to each other. Here, the warp and the weft of the woven fabric include not only those which intersect at right angles to each other but also those which are not right-angled or woven in a wavy form. As described above, a warp and a weft are also included.

[0010] With the above-described structure, a cross section of the warp or the weft of the woven fabric is present at one end surface of the cylindrical portion of the rotary grindstone, and at least one of the warp and the weft is made of the inorganic compound fiber. Allows the surface of the workpiece to be ground and polished. Further, if a large number of extremely thin single yarns are used as the inorganic compound fiber, for example, the diameter of each single yarn is extremely small, so that the surface to be polished and polished can have a smooth and good finish. it can.

On the other hand, warp yarns and weft yarns in which a large number of single yarns are twisted can exert a strong force as a whole, and they are reinforced with a resin or the like and adhered to yarns crossing each other for reinforcement. Thus, a sufficiently strong force for grinding and polishing can be obtained. In addition, since the warp and the weft have appropriate elasticity, the familiarity with the workpiece is improved. In addition, since the single yarn does not fall off like abrasive grains even when the grindstone is worn, its contribution to grinding and polishing is extremely high, and the service life of the grindstone is sufficiently long. In other words, the surface to be polished can be extremely satisfactorily finished while improving the grinding and polishing performance of the rotary grindstone, and the service life thereof can be sufficiently extended.

According to the second aspect of the present invention, both the warp and the weft of the woven fabric are arranged so as to be inclined with respect to the axial direction of the cylindrical portion.

With this arrangement, both the warp yarn and the weft yarn of the woven fabric are arranged so as to be inclined with respect to the axial direction of the cylindrical portion. Since the warp and weft cross sections are present, the density of the cross section of the fiber as the grinding and polishing material is increased, and the grinding and polishing performance is greatly improved. Also, if one of the warp and weft yarns
If the book is arranged so as to be orthogonal to the axial direction of the cylindrical portion, that is, to extend in the circumferential direction, when this yarn appears on the surface to be used due to wear of the grindstone, grinding and polishing by another yarn is performed. However, in the present invention, since all of the warp yarns and the weft yarns are arranged so as to be inclined with respect to the axial direction of the cylindrical portion, the grinding and polishing performance can be stably secured without such a concern. .

According to the third aspect of the present invention, a space not filled with a resin or an inorganic adhesive compound is provided in the cylindrical portion so as to be surrounded by the warp and the weft of the woven fabric. Thus, the space portion is appropriately distributed throughout the cylindrical portion, thereby preventing clogging. In addition, since the warp and the weft are appropriately moderately bent due to the presence of the space, favorable elasticity of the whole grindstone is obtained,
The familiarity between the grindstone and the workpiece is improved, and the finish is further improved.

According to the fourth aspect of the present invention, the cylindrical portion is formed by laminating woven fabrics in the radial direction and bonding them to each other with either a resin or an inorganic adhesive compound. Thus, by laminating the woven fabric, even a large grindstone can be easily manufactured. Further, in the cylindrical portion, the warp yarns and the weft yarns of the woven fabric are connected in a three-dimensional mesh, thereby increasing the rigidity as a whole.

According to the invention of claim 5, the single yarn diameter of the warp yarn and the weft yarn of the woven fabric is 50 μm or less. By doing so, it is possible to make the polishing finer and sufficiently reduce the surface roughness,
The surface to be polished of the workpiece can be finished very well.

In the invention according to claim 6, the woven fabric is made of at least one of alumina fiber, silicon carbide fiber and glass fiber. Thereby, the inorganic compound fiber is embodied, and a woven fabric having sufficient grinding and polishing performance, heat resistance, durability and the like can be obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a rotary grindstone S according to an embodiment of the present invention.
This rotary grindstone S is obtained by laminating a band-shaped woven sheet made of inorganic compound fiber several times (five times in the example in the figure) and then bonding with a resin or the like to form a cylindrical member 1. is there. One end face (upper end face in the figure) 1a of the cylindrical member 1 in the direction of the axis X is dressed, and a surface to be used for grinding and polishing is provided on almost the entire surface. On the other hand, the other end (the lower end in the figure) of the cylindrical member 1 in the direction of the axis X is fixed to a substantially disk-shaped holder 2, 3, and is mounted on a grinding machine via the holder 2, 3. It has become. The rotating grindstone S is used, for example, to rotate while pressing the used surface at the upper end of the drawing against the polished surface of the workpiece such as the outer race of the bearing, and to grind and polish those surfaces with high precision. . A through hole is provided at the center of the holders 2 and 3 along the axis X, and a rotary shaft of a grinding machine is fitted into the through hole.

The fabric sheet constituting the cylindrical member 1 is
It is obtained by cutting a woven fabric of ceramic fiber having sufficient strength for grinding and polishing. More specifically, the woven fabric is formed by twisting a large number of single yarns into twisted or twisted yarns, or by twisting them after twisting the yarns into warp yarns 10a and weft yarns 10b, as shown in FIGS. 2 and 3. Plain weave, satin weave,
It is woven by a method such as twill weaving or quadriaxial weaving (the example shown is plain weaving). The single yarn diameter of this fiber is set to 50 μm or less in order to reduce the roughness of the surface to be polished, but it is preferably about 5 to 20 μm in order to finish the surface to be polished more smoothly. Examples of the ceramic fibers include, for example, high-purity Al2O3, Al2O3-SiO2, Al2
Alumina fibers such as O3-SiO2-B2O3 or the like, silicon carbide fibers, glass fibers or the like may be used, and in this case, a grindstone having sufficient grinding and polishing performance, heat resistance, durability and the like can be obtained.

Here, as schematically shown in FIG.
The warp yarns 10a and the weft yarns 10b of the woven fabric sheet 10 are hardened by an adhesive resin (indicated by phantom lines in the figure) and fixed to each other by the adhesive resin so as to have appropriate elasticity and sufficient strength. Has become. On the other hand, in a portion surrounded by the warp yarns 10a and the weft yarns 10b, a large number of spaces 10c, 10c,... Which are not filled with an adhesive resin are provided, and the warp stones 10a and the weft yarns 10b are allowed to bend. 2 The overall elasticity is increased.

The method of manufacturing the rotary grindstone S will be described. First, a woven fabric of ceramic fibers is immersed in a solution of an adhesive resin having an appropriate concentration prepared in advance, and the woven fabric is pulled up from the solution. The solution existing in the portion surrounded by the weft yarn 10b is removed by suction with a nozzle. Then, after the woven fabric is sufficiently dried, as shown by phantom lines in FIG. 3, a predetermined inclination angle θ (approximately 45 ° in the illustrated example) with respect to the warp yarns 10a and the weft yarns 10b is obtained. It is cut at intervals and strip-shaped woven fabric sheets 10 and 1 are cut.
Get 0, ...

Subsequently, although not shown, the fabric sheet 1
0 is wound around a metal roll having a predetermined outer diameter five times and superposed, and heated while being pressed from the outer peripheral side to cure the adhesive resin. Thereby, the warp 10a of the woven fabric
The warp yarn 10a and the weft yarn 10b are bonded together at a portion where the warp yarn 10a and the weft yarn 10b intersect with each other, and the yarns are also bonded together at the overlapping portion of the woven fabric sheet 10, so that the cylindrical member 1 is formed. It is formed.

The woven fabric may be preliminarily heated and cured, and then cut. In such a case, when the woven fabric sheets 10, 10,... What is necessary is just to apply an adhesive resin.

Then, the cylindrical member 1 obtained as described above is attached and fixed to holders 2 and 3 as shown in FIG. That is, the holder outer member 2 includes a disk-shaped substrate 2a and an annular outer peripheral side wall 2b provided on the outer peripheral edge thereof substantially in parallel with the axis X. The inner diameter of the outer peripheral side wall 2b is the cylindrical member 1 It is slightly smaller than the outside diameter of.
The outer member 2 is placed on a substantially horizontal table, the cylindrical member 1 is fitted inside the outer peripheral side wall 2b, and the disk-shaped holder inner member 3 is further fitted inside the outer member 2b. The outer member 2 is fastened to the outer member 2 at four locations by bolts 4, 4,... At substantially equal intervals in the circumferential direction. This allows
Since the outer diameter of the inner member 3 is slightly larger than the inner diameter of the cylindrical member 1, the lower end of the cylindrical member 1 is sandwiched between the outer peripheral side wall 2 a of the outer member 2 and the inner member 3,
Fixed.

Incidentally, the cylindrical member 1 may be fixed to the outer member 2 or the inner member 3 by an adhesive or a bolt, so that the cylindrical member 1 is more firmly fixed to the holders 2 and 3. Can be fixed to Further, the inner diameter of the outer peripheral side wall portion 2a of the holder outer member 2 and the outer diameter of the inner member 3 were formed larger than the outer diameter and the inner diameter of the cylindrical member 2, respectively, so that the cylindrical member 1 was fixed to the holders 2, 3. In this state, the taper may be tapered toward the use surface 1a. In this way, the use surface 1 at the upper end of the cylindrical member 1
When the a is pressed against the workpiece, the cylindrical member 1 can be prevented from greatly expanding.

In the rotating grindstone S manufactured as described above, the woven fabric sheet 10
The warp yarn 10a and the weft yarn 10b are arranged so as to be inclined at approximately 45 ° with respect to the direction in which the axis X of the cylindrical member 1 extends, so that the upper end surface (one end surface) of the cylindrical member 1, The cross section of all the warp yarns 10a and the weft yarns 10b exists on the use surface 1a. In other words, the cross section of the ceramic fiber that contributes to the grinding and polishing is arranged at a very high density on the use surface 1a of the rotary grindstone S, and high grinding and polishing performance can be obtained. In order to stably maintain the grinding and polishing performance of the warp yarns 10a and the weft yarns 10b by the fiber cross section, the inclination angle of each of the yarns 10a and 10b with respect to the axis X direction is approximately one.
It is preferable to set the inclination angle to approximately 45 °, as described above.

Further, inside the cylindrical member 1, the warp yarns 10a and the weft yarns 10b form a three-dimensional network structure,
In addition to securing sufficient rigidity as a whole, the space portions 10c and 10c are surrounded by the warp yarns 10a and the weft yarns 10b.
Are formed, and the spaces 10c, 10c,... Are appropriately distributed throughout the inside of the cylindrical member 10, so that the warp yarns 10a and the weft yarns 10b are moderately allowed to flex, and a preferable elasticity is obtained. Is obtained. Thereby, the rotating grindstone S has sufficient strength and also has good compatibility with the workpiece.

As the adhesive resin, for example,
A curable resin such as a phenol resin, an epoxy resin, an acrylic resin, and a curable nylon resin may be used, and a ceramic inorganic compound adhesive may be used. If the viscosity of the solution of the adhesive resin for immersing the woven fabric is high, the resin will remain in the spaces 10c, 10c,..., And the size of one space 10c in the woven fabric is taken into consideration. It is necessary to use a solution having an appropriate viscosity. Generally, a solution having a viscosity of 1000 poise or less can be used, but a solution having a viscosity of 300 to 400 poise or less is preferably used. Further, when a solution having a high viscosity must be used, the solution of the adhesive resin is applied to one surface of the woven fabric with a brush or the like, and is strongly sucked from the opposite surface to remove the warp yarn 10a and the weft yarn 10b. The resin between them may be removed.

Therefore, when the rotary grindstone S of this embodiment manufactured as described above is used, the cross section of all the warp yarns 10a and the weft yarns 10b is present on the use surface 1a, and the cross section of the ceramic fiber as the grinding and polishing material is formed. Are arranged at a high density, so that the surface of the workpiece can be ground and polished very effectively by the high-density ceramic fiber cross section.

Further, the warp yarn 10a and the weft yarn 10b
Is made by twisting a large number of single yarns, so it has a strong resistance as an aggregate to the bending force applied from the workpiece, and in addition, many of them are solidified by the adhesive resin and intersect each other. Reinforced with each other, it is possible to obtain a sufficiently strong force for grinding and polishing. On the other hand, the warp yarn 10a and the weft yarn 10b are formed by twisting thin yarns having a single yarn diameter of 50 μm or less.
The roughness of the polished surface to be polished in the cross section of each fine single yarn becomes sufficiently small, and a good finish can be obtained.

Further, the single yarn of the ceramic fiber does not fall off like abrasive grains even when the grindstone is worn, and the grinding and polishing are continuously performed by the large number of single yarns. The contribution of fiber is extremely high,
The service life of the whetstone will be sufficiently long. Moreover, the warp 1
0a and the weft yarn 10b are all arranged so as to be inclined with respect to the direction in which the axis X extends, so that one yarn appears over the entire circumference on the use surface 1a due to the wear of the grindstone, and the other yarns appear. The grinding and polishing by the yarn fibers is not hindered, and the grinding and polishing performance of the grinding wheel S can be stably maintained.

That is, the rotary grinding wheel S according to this embodiment
Can achieve both excellent grinding and polishing performance and good finish of the surface to be polished at a very high level, so it can widely support both grinding and polishing of various materials, and therefore, like a general whetstone There is no need to proceed with the work while gradually changing from coarser to finer ones according to the roughness of the polished surface of the workpiece. This is a revolutionary thing that can be done at once.

Furthermore, since a large number of spaces 10c, 10c,... Are present in the cylindrical member 1 of the rotary grindstone S, the warp yarns 10a and the weft yarns 10b are appropriately allowed to flex, and as a whole are sufficiently large. It has elasticity. Thereby, the familiarity between the rotary whetstone S and the workpiece is improved,
The finish of the surface to be polished is further improved, and grinding and polishing can be performed with a light touch even by hand, so that the usability of the rotary grindstone S is greatly improved. Moreover, since the space portions 10c, 10c,... Are distributed throughout the inside of the cylindrical member 1, fine powder generated due to grinding and polishing is easily discharged, and so-called clogging is prevented. .

In addition, when forming the cylindrical member 1 of the rotary grindstone S, the woven fabric sheets 10, 10,... Are wound around metal rolls to be laminated and integrated, so that a large rotary grindstone can be used. However, it can be easily manufactured.

It should be noted that the present invention is not limited to the above-described embodiment, but includes other various embodiments. For example, in the above embodiment, the woven fabric forming the cylindrical member 1 of the rotary grindstone S has both the warp yarn 10a and the weft yarn 10b made of ceramic fibers, but only one of the woven fabric warp yarn 10a and the weft yarn 10b. May be made of ceramic fiber, and the other may be made of, for example, nylon fiber.

In the above embodiment, the warp 10 of the woven fabric is used.
a and the weft 10b are fixed with an adhesive resin so that the spaces 10c, 10c,... remain in the cylindrical member 1, but the space 10c does not always need to be intentionally provided. Further, in the cylindrical member 1, the warp yarn 10
a and the weft 10b do not necessarily need to be arranged so as to be inclined with respect to the direction in which the axis X extends.
There may be a thread extending in parallel with.

Further, in the above embodiment, the radial dimension of the holders 2 and 3 for fixing the lower end of the cylindrical member 1 is formed slightly smaller than that of the cylindrical member 1, and the cylindrical member 1 is fixed to the holders 2 and 3. It may be formed in a tapered shape that expands toward the use surface 1a in the state of being turned. In this way, when the rotary grindstone S is mounted on a rotary drill or the like and is manually pressed against the workpiece, the rotary drill can be easily held and workability can be improved.

[0039]

Next, a specific embodiment will be described. In this embodiment, first, 2880 single yarns having a diameter of 7 μm of alumina fiber were bundled and twisted, and used as warp yarns and weft yarns.
A plain woven cloth woven to a density of 25 mm was prepared.
Then, as described in the above embodiment, the woven fabric was immersed in a methanol solution of a phenol resin having a concentration of 5%, pulled up, and then sucked with a nozzle having a hole diameter of 1 mm to suck the solution in the space.

Subsequently, the woven fabric is sufficiently dried at a temperature of about 100 ° C., and cut at an angle of about 45 ° with respect to both the warp yarn and the weft yarn. Woven fabric sheet. This woven sheet has a diameter of about 2
Wrap 5 times around a 00mm metal roll and temporarily fix it.
It was cured by heating at a temperature of 50 ° C. for 20 minutes to form a cylindrical member. Then, the lower end of the cylindrical member was fixed to the holder, while the upper end was dressed to obtain a test piece of a rotary grindstone.

The rotating grindstone obtained as described above was mounted on a grinder, and the surface of a stainless steel plate having a width of 500 mm and a length of 10 m was polished by a predetermined amount over the entire surface. Was about 0.5 mm. In addition, the surface to be polished of the stainless steel plate was glossy and had a good finish with almost no polished eyes. On the other hand, as a comparative example, when a stainless steel plate was polished in the same manner as described above using a cup-type grindstone having a diameter of about 200 mm and containing commercially available JIS # 180 abrasive grains, the wear amount of the grindstone was about 3 mm.
mm, which is much larger than that of the example, and in this comparative example, a clear polished grain was seen on the surface of the polished surface.

Therefore, according to the above test results, the rotary grindstone according to the present invention has much higher grinding and polishing performance and a finer surface finish of polishing than the conventional type using abrasive grains. In addition, it has been proved that it has an excellent property of having a long life.

[0043]

As described above, according to the rotary grindstone according to the first aspect of the present invention, a woven fabric containing inorganic compound fibers is solidified with a resin or the like to form a cylindrical shape, and one end surface in the axial direction is formed on one end surface thereof. Since the surface to be used for grinding and polishing is provided, the surface of the workpiece can be ground and polished by the cross-section of the inorganic compound fibers of the warp and weft yarns of the woven fabric present on the surface to be used, and a smooth and good finish can be obtained. Since the warp and the weft are hardened by a resin or the like and reinforced with each other, high grinding and polishing performance can be obtained. In addition, since the inorganic compound fibers do not fall off like abrasive grains, the contribution rate thereof can be sufficiently increased, and the service life of the grindstone can be extended. In other words, the surface to be polished can be extremely satisfactorily finished while improving the grinding and polishing performance of the rotary grindstone, and the service life thereof can be sufficiently extended.

According to the second aspect of the present invention, by arranging both the warp and the weft of the woven fabric so as to be inclined with respect to the axial direction of the cylindrical portion, the density of the cross section of the inorganic compound fiber on the surface of use of the rotary grindstone can be improved. , The grinding and polishing performance can be greatly improved, and the grinding and polishing performance can be ensured stably.

According to the third aspect of the present invention, clogging can be prevented by providing a space in which the resin or the inorganic adhesive compound is not filled in the cylindrical portion of the rotary grindstone. In addition, since a suitable elasticity can be obtained as a whole of the grindstone, the familiarity between the grindstone and the workpiece can be improved, and the finish can be further improved.

According to the fourth aspect of the present invention, the woven fabric is laminated in the radial direction and bonded with a resin or the like to form a cylindrical portion. Therefore, even a large grindstone can be easily manufactured. The rigidity of the whole grindstone can be increased.

According to the fifth aspect of the invention, by setting the single yarn diameter of the fibers of the woven fabric to 50 μm or less, the effect of smoothly finishing the surface to be polished can be sufficiently obtained.

According to the sixth aspect of the present invention, by using alumina fibers or the like as the fibers of the woven fabric, a rotary grindstone having both sufficient grinding / polishing ability and durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a rotary grindstone according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of warp yarns, weft yarns, and spaces in a woven fabric sheet.

FIG. 3 is an explanatory diagram showing a cutting direction of a woven fabric.

FIG. 4 is an exploded perspective view showing a procedure for assembling a cylindrical member of a rotary grindstone to a holder.

[Explanation of symbols]

 S Rotating whetstone 1 Cylindrical member 2 Holder outer member 3 Holder inner member 10 Textile sheet 10a Warp yarn 10b Weft yarn 10c Space

Claims (6)

[Claims] 1. A rotary grindstone having a use surface for grinding and polishing provided at one axial end surface of a cylindrical portion, wherein the cylindrical portion is made of a woven fabric in which at least one of a warp or a weft is made of an inorganic compound fiber. The rotating grindstone formed, wherein the warp yarn and the weft yarn of the woven fabric are hardened by one of a resin and an inorganic adhesive compound and adhered to each other. 2. The rotary grindstone according to claim 1, wherein both the warp yarn and the weft yarn of the woven fabric are arranged so as to be inclined with respect to the axial direction of the cylindrical portion. 3. The method according to claim 1, wherein the cylindrical portion is surrounded by a warp and a weft of a woven fabric.
A rotary grindstone characterized by having a space portion not filled with a resin or an inorganic adhesive compound. 4. The rotary grinding wheel according to claim 1, wherein the cylindrical portion is formed by laminating woven fabrics in a radial direction and bonding each other with a resin or an inorganic adhesive compound. 5. The grindstone according to claim 1, wherein the single yarn diameter of the warp yarn and the weft yarn of the woven fabric is 50 μm or less. 6. The rotating grindstone according to claim 1, wherein the woven fabric is made of at least one of alumina fiber, silicon carbide fiber, and glass fiber.