JPH0716888B2 - Grinding and grinding wheel, manufacturing method thereof and manufacturing apparatus thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset type grindstone for grinding and polishing, a manufacturing method thereof, and a manufacturing apparatus thereof.

(Prior Art) As a rotary grindstone mounted on a grinder or the like, an offset type grinding / polishing grindstone in which abrasive grains are bonded with a phenol resin-based binder is generally known. And, in this grindstone, it is usual to embed a coarse plain weave glass cloth formed by prepreging a phenol resin as a reinforcing core material.

However, in such a grindstone, in order to give flexibility to the grindstone, one in which irregularities such as a mesh pattern are formed on the grinding surface of the grindstone is generally known (for example, Japanese Patent Publication No. 50-35270).
(See the official gazette). The grindstone is placed on an elastic plate such as a rubber plate and pressed from above to artificially form a crack at the bottom of the recess. In this case, a non-woven fabric is provided on the back surface of the grindstone so that the cracks do not stand out.

(Problems to be solved by the invention) However, in a means for imparting flexibility (flexibility) to the grindstone by forming an artificial crack in the bottom of the concave portion of the grindstone, the artificial crack becomes uneven. Since it is easy, it is difficult to give uniform flexibility to the entire circumference of the grindstone. Therefore, in the conventional grindstone, since the grindstone cannot be flexed flexibly due to the nonuniformity of the flexibility, the contact surface with respect to the workpiece is reduced and high cutting efficiency cannot be expected.

Further, as described above, the unevenness of the grindstone's flexibility means that the grindstone's contact with the work piece is also non-uniform, which causes uneven wear on the outer peripheral edge of the grinding part of the grindstone. This causes uneven contact of the grindstone to the work piece, scratches the work piece, and even breaks the grindstone, that is, breaks near the offset part. The reality is that stable grinding and polishing cannot be performed over time.

Furthermore, it is difficult to change the degree of flexibility of the grindstone by means of forming an artificial crack at the bottom of the recess of the grindstone described above, and various kinds of grindstones having different flexibility depending on the content of grinding and polishing work can be performed. Difficult to provide.

That is, an object of the present invention is to provide a grinding and polishing grindstone which has uniform flexibility over the entire circumference in the circumferential direction and which can widen a contact surface to a work piece without causing a waist break and its manufacturing. A method and a manufacturing apparatus therefor are provided.

(Means for Solving the Problems) In order to solve such problems, the present invention provides a back surface of an abrasive material layer, which is more elastic than the abrasive material layer, at least in the range from the offset portion to the outer peripheral edge of the grindstone. By providing a material layer in the circumferential direction of the grindstone to provide uniform flexibility over its entire circumference, by gradually reducing the thickness of the back material layer from the offset portion to the outer peripheral edge, In the radial direction of the grindstone, it is possible to give substantially uniform flexibility according to the purpose of the grinding and polishing work.

That is, the grinding / polishing grindstone according to the invention of claim (1) is an offset type grinding / grinding grindstone in which a backing material layer is provided on the back surface of an abrasive layer formed by bonding abrasive grains with a binder. The backing material layer is made of a material that is more elastic than the abrasive layer, and is provided in the range from the outer peripheral edge of the grinding portion of the grindstone to the offset portion. It is characterized in that the thickness of the backing material layer is gradually increased.

The grinding / polishing grindstone according to the invention of claim (2) is the grinding / polishing grindstone of the above-mentioned claim (1), in which the thickness of the abrasive layer is gradually reduced from the outer peripheral edge of the grinding part to the offset part. It is characterized by being

A grindstone for grinding and polishing according to the invention of claim (3) is the grindstone for grinding and polishing according to claim (1) or (2), wherein reinforcement is provided between the abrasive layer and the backing material layer. The heartwood is interposed.

The grindstone for grinding and polishing according to the invention of claim (4) is the grindstone for grinding and polishing according to claim (2) or (3), wherein the outer peripheral portion of the grinding portion is thicker than the inner peripheral portion. In addition, the thickness of the abrasive material layer at the outer peripheral portion of the grinding portion is made thicker than the thickness at the inner peripheral edge of the grinding portion of the backing material layer.

A grinding and polishing grindstone according to the invention of claim (5) is the grinding and grinding grindstone according to any one of claims (1) to (4), wherein the binder of the abrasive layer is phenol. A resin or an epoxy resin is used, and the backing material layer is made of a resin material similar to the above binder.

Further, in manufacturing the grinding and polishing grindstone, the filling thickness of the grinding material and the backing material may be changed when the grindstone material is pressure-molded by the upper die and the lower die.

That is, the method for producing a grinding and polishing grindstone according to the invention of claim (6) is for offset type grinding and polishing in which a backing material layer is provided on the back surface of an abrasive material layer formed by bonding abrasive grains with a binder. A method of manufacturing a grindstone, in which a lower die having a molding surface corresponding to the back surface shape of the grindstone, the backing material is gradually thinned in a radial direction from a portion where the offset portion of the grindstone on the molding surface of the lower die is molded. Lay it on top of it and put a reinforcing core on it,
A grinding material composed of abrasive grains and a binder is laid on the reinforcing core material so that the thickness gradually increases in the radial direction from the portion where the offset portion is molded, and pressure molding is performed by an upper die, followed by firing. It is characterized by that.

Further, in order to carry out the above-mentioned manufacturing method, the filling thickness of the backing material in the lower mold may be changed.

That is, the manufacturing apparatus of the grinding and polishing grindstone according to the invention of claim (7) is used for the manufacturing method of the above-mentioned claim (6), and has a molding surface corresponding to the back surface shape of the grindstone, and There is a lower die with a core rod protruding upward from the center, and a fitting hole for fitting the core rod in the center, and the space between the lower die and the molding surface of this lower die is this molding surface. A first upper die forming a cavity for forming a backing material layer, which is gradually narrowed in a radial direction from a portion for forming an offset portion of a grindstone, and a fitting hole for fitting the core rod in the center, The first upper mold is removed, the second upper mold is fitted to the lower mold, and a second upper mold is formed between the lower mold and a molding surface of the lower mold to form a cavity for forming a grindstone.

An apparatus for manufacturing a grindstone for grinding and polishing according to the invention of claim (8) is used in the manufacturing method of the above-mentioned claim (6), and has a forming surface corresponding to the back surface shape of the grindstone, and The lower die with the core rod protruding upward is rotatably provided around the core rod, and the distance between the lower die forming surface and the forming surface of the lower die gradually increases in a radial direction. The leveling tool has a leveling surface inclined so as to be narrow, and has a leveling tool for leveling the backing material put into the molding surface, and a fitting hole in the center for fitting the core rod, It is characterized by including an upper mold which is fitted to the lower mold in a state where the mold is removed, and which forms a grinding stone molding cavity with the molding surface of the lower mold.

(Function) In the grindstone for grinding and polishing according to the above-mentioned claim (1), the abrasive layer itself has low toughness and is easily broken, but the backing material layer prevents the abrasive layer from breaking and imparts toughness to the grindstone. Since the backing material layer is made of a material having substantially uniform strength, the flexibility of the grindstone in the circumferential direction is substantially uniform over the entire circumference of the grindstone. Then, since the thickness of the backing material layer is gradually increased from the outer peripheral edge of the grinding portion of the grindstone to the offset portion, the rigidity of the grindstone becomes strong, and the grindstone breaks near the offset portion during the grinding work. To be prevented.

In the grindstone for grinding and polishing according to the above-mentioned claim (2), when the grindstone of the grindstone is pressed against the workpiece, the bending moment becomes larger as the position is farther from the center. The thickness of the abrasive layer is gradually reduced toward the offset portion, and the strength is low, so that the entire length of the abrasive portion in the radial direction is bent substantially evenly.
In other words, it becomes possible to bend with substantially the same radius of curvature. Then, since the thickness of the backing material layer is gradually increased from the outer peripheral edge of the grinding portion to the offset portion, it prevents the grinding stone from being broken due to the gradually decreasing thickness of the grinding material layer. Will be done. Of course, by changing the rate of change of the thickness of the abrasive material layer and the backing material layer, for example, the amount of bending can be reduced toward the outer peripheral edge of the ground portion.

Further, in the grinding / polishing grindstone according to claim (3), since the reinforcing core material is interposed between the abrasive layer and the backing material layer, the strength of the grinding portion is increased, and the grindstone is especially resistant to the rotational centrifugal force. It becomes possible to give tensile strength.

In the grindstone for grinding and polishing according to claim (4), since the thickness of the outer peripheral portion of the grinding portion is increased to make the abrasive material layer a layer thickness, the amount of grinding and polishing of the grindstone can be increased.

In the grindstone for grinding and polishing according to claim (5), since the backing material layer is composed of a resin material of the same type as the binder of the abrasive material layer, the adhesion of both layers is good and the backing material layer is good. The strength of can be made uniform.

In the manufacturing method according to claim (6), the filling thickness of the backing material is gradually increased from the portion corresponding to the outer peripheral edge of the grinding portion of the grindstone to the portion corresponding to the offset portion, and Since the filling thickness is gradually reduced from the portion corresponding to the outer peripheral edge of the grinding portion to the portion corresponding to the offset portion, pressure molding is performed,
The backing material layer and the abrasive layer each have a thickness corresponding to the filling thickness of the above material, and the above grinding and polishing whetstone can be obtained.

In the manufacturing apparatus according to claim (7), the backing material gradually widened from the portion corresponding to the outer peripheral edge of the grinding portion of the grindstone to the portion corresponding to the offset portion by the first upper die and the lower die. Since it is possible to configure the cavity for layer forming, the filling thickness of the backing material is gradually increased from the portion corresponding to the outer peripheral edge of the grinding portion of the grindstone to the portion corresponding to the offset portion, It is possible to place the reinforcing core material on top of this and to add the grinding material from above to press-form the grindstone.

In the manufacturing apparatus according to claim (8), when the backing material is put into the lower mold and the leveling tool is rotated, the backing material corresponds to the offset portion from the portion corresponding to the outer peripheral edge of the grinding portion. It is possible to lay it so that the thickness gradually increases as it goes to the part, place the reinforcing core material on it, and add the grinding material from there, and press-form the grindstone.

(Effect of the invention) Therefore, according to the grindstone for grinding and polishing of claim (1), the flexibility of the grindstone is adjusted by the backing material layer so that the flexibility of the grindstone is uniform over the entire circumference thereof. As a result, it is possible to carry out stable grinding and polishing for a long period of time without causing uneven wear, and to prevent bending of the grindstone.

According to the grindstone for grinding and polishing of claim (2), when the grinding portion is pressed against the workpiece, it can be curved with a desired radius of curvature to widen the contact surface with the workpiece. The cutting efficiency can be improved. Moreover, since the thickness of the abrasive layer is gradually reduced from the outer peripheral edge of the grinding portion to the offset portion, it is possible to reduce the grinding material without reducing the effective cutting portion of the grindstone, that is, resource saving. Further, since it is not necessary to provide a non-woven fabric for covering the cracks on the grindstone, it is possible to reduce the manufacturing cost of the grindstone.

According to the grinding and polishing grindstone of claim (3), the strength of the grinding portion can be increased by the reinforcing core material so that the grindstone can withstand high speed rotation.

According to the grinding and polishing grindstone of claim (4), since the abrasive material layer has a layer thickness, the grinding and polishing work can be continued for a long time with one grindstone, that is, without exchanging it.

According to the grinding / polishing grindstone of claim (5), the backing material layer is made of a resin material of the same type as the binder of the abrasive material layer, whereby the adhesion between the two layers is increased and the backing material is The strength of the layer can be made uniform to improve the quality of the grindstone.

According to the manufacturing method of claim (6), the grindstone for grinding and polishing can be easily obtained by adjusting the filling thickness of the grinding material and the backing material in the mold.

According to the manufacturing apparatus of claim (7), the filling thickness of the backing material is changed from the portion corresponding to the outer peripheral edge of the grinding portion of the grindstone to the portion corresponding to the offset portion by the first upper mold and the lower mold. The thickness can be gradually increased as it goes, and the invention of claim (6) can be carried out.

According to the manufacturing apparatus of claim (8), by rotating the leveling tool, the thickness of the backing material gradually increases as it goes from the portion corresponding to the outer peripheral edge of the grinding portion to the portion corresponding to the offset portion. The thickness of the backing material is made uniform over the entire circumference of the whetstone so that
The invention can be carried out.

(Example) Hereinafter, the Example of this invention is described based on drawing.

In the offset grinding / polishing grindstone 1 shown in FIG. 1,
Reference numeral 2 is an annular grinding portion, and 3 is an offset portion protruding from the grinding portion 2 in a truncated cone shape. Irregularities such as a mesh pattern shown in FIG. 2 are formed on the grinding surface 4 of the grinding portion 2. Further, a cored bar 6 having a central hole 5 for attaching the grindstone 1 to the rotary shaft of the grinder is attached to the center of the offset portion 3.

As shown in FIG. 3, the grindstone 1 has a structure in which an abrasive material layer 7 and a backing material layer 8 provided on the back surface of the abrasive material layer 7 are laminated with a reinforcing core material 9 interposed therebetween. There is. The abrasive layer 7 is composed of abrasive grains bonded with a binder,
Alumina-based abrasives are used as the abrasive grains, and phenolic resin-based ones are used as the binder. Further, on the outer peripheral edge of the grinding portion 2 in the abrasive layer 7, a sloped surface 7a is formed facing outward and obliquely downward. On the other hand, the backing material layer 8
Is composed of a modified phenolic resin material and a glass fiber (reinforcing material impregnated with a similar resin) so that the elastic modulus is smaller than that of the abrasive layer 7 and the strength is substantially uniform. It is provided in the range from to the offset portion 3, that is, the entire back surface of the grindstone 1. The reinforcing core material 9 is made of glass cloth that is prepreged with a phenol resin, and provides the grindstone 1 with a tensile strength against a rotational centrifugal force.

The thickness of the abrasive layer 7 is gradually reduced from the outer peripheral edge of the grinding portion 2 to the offset portion 3, and the offset portion 3 is a thin layer having a constant thickness. On the other hand, the backing material layer 8 is gradually thickened from the outer peripheral edge of the grinding portion 2 to the offset portion 3, and the offset portion 3 is a thick layer having a constant thickness.

Therefore, in the grindstone 1, since the thickness of the abrasive layer 7 is gradually reduced from the outer peripheral edge of the grinding portion 2 to the offset portion 3, the outer circumference of the grinding portion 2 becomes closer to the offset portion 3 side. The strength is lower than that on the edge side. On the other hand, the backing material layer 8 prevents the abrasive material layer 7 from being broken and imparts toughness to the grindstone 1. However, the thickness of the backing material layer 8 changes from the outer peripheral edge of the grinding portion 2 to the offset portion 3. Since the thickness of the grindstone 1 is gradually increased as it goes, the strength of the grindstone 1 becomes lower from the outer peripheral edge of the grinding part 2 to the offset part 3, but its toughness becomes higher. Further, since the backing material layer 8 is composed of a material having a uniform strength,
The grindstone 1 has uniform flexibility over the entire circumference in the circumferential direction. In the grindstone 1, since the binder of the abrasive layer 7 is made of a phenol resin and the backing material layer 8 is made of a phenol resin material, the adhesion between both layers is good.

Then, in the grinding and polishing work with the grindstone 1,
When this grindstone 1 is pressed against the processed surface of the workpiece with an inclination of 15 to 30 degrees which is a normal use angle, the change in the layer thickness between the abrasive layer 7 and the backing material layer 8 in the radial direction of the grindstone. As a result, the grinding portion 2 of the grindstone 1 is curved with substantially the same radius of curvature over the entire length from the offset portion 3 side to the outer peripheral edge of the grinding portion 2 as shown by the chain line in FIG.

That is, if the thickness of the grinding material layer 7 of the grinding portion 2 is the same over the entire length in the radial direction, when the outer peripheral edge of the grinding portion is pressed against the workpiece, the bending moment increases as the position is farther from the center of the grindstone. Since it becomes larger, the radius of curvature becomes smaller as it goes from the offset portion side to the outer peripheral edge of the grinding portion, so that the contact surface with respect to the workpiece becomes narrower. On the other hand, in the case of the grindstone 1, the thickness of the abrasive layer 7 increases from the offset portion side to the outer peripheral edge of the grinding portion, and the strength increases. 2 is curved with substantially the same radius of curvature over the entire length up to the outer peripheral edge, and the radius of curvature is larger at the outer peripheral edge of the grinding portion 2 than that of the abrasive material layer having the same thickness. The contact surface becomes wider.

Further, of course, by changing the rate of change in the thickness of the abrasive layer 7 and the backing material layer 8, for example, the amount of bending is reduced as the grinding portion 2 is moved to the outer peripheral edge, so that the peripheral portion near the outer peripheral edge is reduced. It is also possible to further widen the contact surface with respect to the workpiece.

Therefore, according to the grindstone 1, the grinding efficiency of the work piece is increased, and nevertheless, the grinding resistance is not increased due to the flexibility, and the grinding surface of the grindstone 1 is efficiently worn in a state where the wear is small. Grinding and polishing can be performed. Further, as described above, since the thickness of the abrasive layer 7 of the grindstone 1 is gradually reduced from the outer peripheral edge of the grind part 2 to the offset part 3, the effective cutting part of the grindstone 1 is ground without being reduced. The material can be reduced, and further, since it is not necessary to provide a non-woven fabric for covering the cracks in the grindstone 1, it is possible to reduce the manufacturing cost of the grindstone 1.

Further, if the backing material layer 8 is composed of phenol resin and glass fiber as in the above embodiment, the elastic modulus of the backing material layer 8 can be adjusted by this glass fiber and the phenol If the reinforcing core material 9 is punched and molded from a glass cloth prepregged with resin, the residual material of the glass cloth is crushed to form the glass fiber material of the backing material layer 8, which is conventionally discarded. In addition, the remaining material can be effectively used to save resources.

Next, a method of manufacturing the grindstone 1 and an apparatus thereof will be described.

An example of the manufacturing apparatus is shown in FIG. 4 to FIG.
In FIG. 4, 11 is a lower mold having an upward forming surface 12 corresponding to the shape of the back surface of the grindstone 1, 13 is fitted to the lower mold 11,
A first upper mold having a downwardly facing molding surface 14 for forming a cavity for molding the backing material layer between the molding surface 12 and the molding surface 12. Further, 15 is a core rod for forming the central hole 5 of the grindstone 1, 16 is an annular die which is fitted on the lower die 11 to form the outer peripheral edge of the grindstone 1, and the lower die 11 and the upper die 13 Fitting holes 17 and 18 into which the core rod 15 is fitted are formed in the center, and the upper mold 13
Is fitted into the annular mold 16 from above.

On the molding surface 12 of the lower mold 11, the portion 12a for forming the grinding portion 2 of the grindstone 1 is made flat, and the portion 1 for forming the offset portion 3 is formed.
2b is depressed like an inverted truncated cone. On the other hand, in the molding surface 14 of the first upper die 13, the portion 14a corresponding to the grinding portion 2 is offset from the outer peripheral edge of the portion 12a of the grinding surface 2 of the lower die 11 where the grinding portion 2 of the grindstone 1 is formed. The cavity 14 is inclined so that the vertical width of the cavity gradually becomes wider toward the portion 12b to be molded, and the portion 14b corresponding to the offset portion 3 is the lower mold 1
It is parallel to the relevant portion 12b of 1.

Then, 19 shown in FIG. 5 is fitted to the lower mold 11 with the first upper mold 13 removed to form a grinding stone forming cavity between the lower mold 11 and the molding surface 12. A second upper mold having a downwardly facing molding surface 20. Forming surface 20 of this upper mold 19
The portion 20a for forming the grinding portion 2 of the grindstone 1 and the portion 20b for forming the offset portion 3 are respectively parallel to the corresponding portions of the lower mold 11, and the portion 20a for forming the grinding portion 2 is provided. Is provided with irregularities so as to obtain the ground surface 4 having the irregular pattern described above. Also, the second upper mold 19 has a first
A fitting hole 21 is formed similarly to that of the upper mold 13.

FIG. 6 shows a leveling tool 25 for leveling the backing material put on the molding surface 12 of the lower mold 11.

That is, the leveling tool 25 is provided rotatably around a portion of the lower die 11 corresponding to the axis of the grindstone 1 supported by the rotation driving means 26, that is, the core rod 15.
The rotation driving means 26 is supported by the lifting means (cylinder device) 27.
It can be moved up and down with, and this leveling tool 25
The lower surface of the lower die 11 is formed with a leveling surface 25a that is inclined so as to be gradually narrowed in a radial direction from a portion 12b of the grinding surface 1 where the offset portion 3 of the grinding stone 1 is formed.

Then, the lower mold 11 has a backing material filling station, a first pressure station, an abrasive material filling station, and a second material filling station.
The leveling tool 25 is transferred to the backing material filling station, the first upper mold 13 is moved to the first pressing station, and the second upper mold 19 is moved to the first pressing station. The two pressurizing stations are respectively arranged so as to be able to move up and down.

Next, a method for manufacturing the above grindstone will be described.

At the backing material filling station, as shown in FIG. 4, the backing material for forming the backing material layer 8 is filled in the lower die 11 in which the core rod 15 and the annular die 16 are assembled. Then, the leveling tool 25 is lowered by the elevating means 27 and rotated by the rotation driving means 26. As a result, the thickness of the backing material on the molding surface 12 of the lower die 11 gradually increases from the outer peripheral edge of the portion 12a for forming the grinding portion 2 of the grindstone 1 to the portion 12b for forming the offset portion 3. Is smoothed out. After that, the leveling tool 25 is raised.

Next, in the first pressure station, the reinforcing core material 9 is placed on the leveled backing material. And the lower mold 11 is first
The upper mold 13 is lowered to be fitted, and the backing material layer 8 is preformed by heating under pressure. That is, this lower mold
In the cavity composed of 11 and the first upper mold 13,
The polymerization reaction of the phenol resin of the backing material is allowed to proceed until the surface is cured. After that, the first upper mold
Raise 13

Next, in the abrasive material filling station, an abrasive material for forming the abrasive layer 7 is put on the reinforcing core material 9. In this case, the abrasive material is a resin coated grain obtained by coating abrasive particles with a liquid phenol resin as a binder and then spraying powdered phenol resin as a binder. Further, the introduced grinding material is leveled by a leveling tool (not shown) having a leveling surface parallel to the molding surface 12 of the lower mold 11 as in the case of the backing material.

Next, in the second pressurizing station, the cored bar 6 is mounted, the second upper mold 19 is lowered and aligned with the lower mold 11, and the above-mentioned grindstone 1 is obtained by heating and firing under pressure.

Therefore, according to this manufacturing method, the backing material for forming the backing material layer 8 is evenly heat-pressed by the leveling tool 25, and the surface thereof is hardened. It is possible to reliably obtain the backing material layer 8 whose thickness gradually increases from the outer peripheral edge of the grinding portion 2 to the offset portion 3 without causing the die to be deformed by the pressure applied by the upper die 19 of 2. .

In the above method, the backing material is leveled by the leveling tool 25 and then pressed by the first upper mold 13, but the leveling tool 25 may not be used. That is, in this case, the backing material is accurately weighed and filled in the lower mold 11, and this is heated and pressed by the first upper mold 13 to be preformed. When a highly fluid material such as a liquid is used as the backing material, the backing material is injected into the cavity formed by the first upper mold 13 and the lower mold 11 in a state of being aligned with each other. May be.

It is also possible to manufacture the grindstone 1 using the leveling tool 25 and without using the first upper mold 13. That is, in this case,
After the leveling process of the backing material by the leveling tool 25, the backing material is heated and pressed in a firing furnace to such an extent that the surface thereof is hardened and sent to the above-mentioned abrasive material filling station.

Further, in the above-mentioned embodiment, the lower mold is filled with the backing material and then the grinding material, but the filling order may be reversed. That is, in this case, a grinding material composed of abrasive grains and a binder is radiated to a lower mold having a molding surface corresponding to the surface shape of the grindstone 1 from a portion on the molding surface of the lower mold where the offset portion of the grinding stone is molded. The thickness of the backing material should be gradually increased in the direction, and the backing material should be laid on the offset portion so that the thickness becomes thinner from the portion where the offset portion is to be formed. become.

FIG. 7 shows a grindstone 31 of another embodiment.

That is, the basic structure of the grindstone 31 is the same as the previous embodiment, the annular grinding portion 32 and the offset portion 33 is provided, and the grinding surface 34 is formed with irregularities such as a mesh pattern,
A core metal 36 having a center hole 35 is attached to the offset portion 33, and a reinforcing material 39 is provided between the abrasive layer 37 and the backing material layer 38.
Is installed. However, unlike the previous embodiment, the grinding portion 32 has a thicker outer peripheral portion than the inner peripheral portion, and the abrasive material layer 37 has a wall thickness of the outer peripheral portion of the grinding portion at the inner peripheral edge of the grinding portion of the backing material layer 38. It is made thicker than the wall thickness. And
The backing material is used for the offset portion 33, and the grinding material is used only for the grinding portion 32.

Therefore, according to the above-mentioned grindstone 31, it is not necessary to provide the abrasive material in the offset portion 33, and the thickness of the abrasive material layer 37 in the outer peripheral portion of the abrasive portion 32 is increased by that much, so that the amount of the entire abrasive material is too small. It is possible to increase the amount of grinding and polishing with one grindstone without increasing.

The grindstone 31 can be manufactured in the same manner as in the previous embodiment by changing the shape of the upper mold 19 in the above embodiment to a shape corresponding to the shape of the abrasive layer 37.

In each of the above examples, one glass cloth was used as the reinforcing core material 9,39, but it is also possible to increase the tensile strength of the grindstone by using a plurality of glass cloths. ,
It can be embedded in 38 to adjust its elastic modulus.

Further, as the abrasive grains of the abrasive layers 7, 37, other abrasives such as silicon carbide (carborundum) -based or natural abrasives can be used. Further, a thermosetting resin other than a phenol type resin, for example, an epoxy modified resin can be used for the binder and the backing material layers 8 and 38. By using this epoxy-modified resin, the grindstone can be colored as desired.

When a non-woven fabric made of fibers or the like prepreged with a synthetic resin material is provided on the back surface of the grindstones 1, 31, the non-woven fabric is laid on the lower mold 11 before the backing material filling step and heated and pressed. After that, it will be sent to the backing material filling station.

[Brief description of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a side view of a grindstone,
FIG. 2 is a plan view showing a grindstone partially omitted, FIG. 3 is an enlarged sectional view showing a part of the grindstone, and FIG. 4 is a sectional view showing a relationship between a lower die and a first upper die. 5 is a sectional view showing the relationship between the lower mold and the second upper mold, FIG. 6 is a sectional view showing the relationship between the lower mold and the leveling tool, and FIG. 7 is another embodiment of the grindstone. It is sectional drawing which expands and shows similarly to FIG. 1,31 …… Whetstone 2,32 …… Grinding part 3,33 …… Offset part 4,34 …… Grinding surface 7,37 …… Grinding material layer 8,38 …… Backing material layer 9,39 …… Reinforcement Core material 11 …… Lower mold 12 …… Molding surface 12a …… Parts for forming grinding part 12b …… Parts for forming offset part 13 …… First upper mold 14 …… Molding surface 14a …… Corresponds to grinding part Part 14b: Part corresponding to the offset part 3 ... Core rod 19 ... Second upper mold 20 ... Molding surface 25 ... Leveling tool 25a ... Leveling surface

Claims (8)

[Claims] 1. An offset type grinding / polishing wheel having a backing material layer provided on the back surface of an abrasive material layer in which abrasive grains are bonded with a binder, wherein the backing material layer is more elastic than the abrasive material layer. It is made of a material that has, and is provided in the range from the outer peripheral edge of the grinding portion of the grindstone to the offset portion, and the thickness of the backing material layer is gradually increased from the outer peripheral edge of the grinding portion to the offset portion. A grindstone for grinding and polishing characterized by being 2. The grindstone for grinding and polishing according to claim 1, wherein the thickness of the abrasive layer is gradually reduced from the outer peripheral edge of the grinding portion toward the offset portion. 3. The grindstone for grinding and polishing according to claim 1 or 2, wherein a reinforcing core material is interposed between the abrasive layer and the backing material layer. 4. An outer peripheral portion of the grinding portion is made thicker than an inner peripheral portion thereof, and an abrasive material layer is formed such that an outer peripheral portion of the grinding portion is thicker than an inner peripheral edge portion of the backing material layer. The grindstone for grinding and polishing according to claim (2) or (3). 5. The binder of the abrasive material layer is a phenolic resin or an epoxy resin, and the backing material layer is made of a resin material of the same type as the binder. The grindstone for grinding and polishing according to any one of 4). 6. A method of manufacturing an offset type grinding and grinding wheel in which a backing material layer is provided on the back surface of an abrasive layer formed by bonding abrasive grains with a binder, which corresponds to the shape of the back surface of the grinding stone. In the lower mold having a molding surface, the backing material is laid so that the thickness gradually decreases in the radial direction from the portion where the offset portion of the grindstone on the molding surface of the lower mold is molded, and the reinforcing core material is placed on it.
The abrasive material consisting of abrasive grains and a binder is laid from above the reinforcing core material so that the thickness gradually increases in the radial direction from the portion where the offset portion is formed, and pressure-molded by the upper die,
A method of manufacturing a grindstone for grinding and polishing, which comprises firing. 7. An apparatus used in the manufacturing method according to claim 6, comprising a lower mold having a molding surface corresponding to the shape of the back surface of the grindstone and having a core rod protruding upward from the center. It has a fitting hole for fitting the core rod in the center, and it is aligned with the lower mold, and its distance from the molding surface of the lower mold is gradually increased in the radial direction from the portion for molding the offset portion of the grindstone on the molding surface. It has a first upper mold forming a narrowed cavity for forming the backing material layer and a fitting hole in the center for fitting the core rod, and is fitted to the lower mold with the first upper mold removed. An apparatus for manufacturing a grindstone for grinding and polishing, comprising: a second upper mold that forms a cavity for molding a grindstone between the molding surface of the lower mold. 8. An apparatus used in the manufacturing method according to claim 6, comprising a lower mold having a molding surface corresponding to the shape of the back surface of the grindstone and having a core rod protruding upward from the center. It is rotatably provided around the core rod, and has a leveling surface that is inclined so that the distance from the molding surface of the lower mold is gradually narrowed in the radial direction from the portion that molds the offset portion of the grindstone on this molding surface, It has a leveling tool for leveling the backing material put in the molding surface, and a fitting hole for fitting the core rod in the center, and with the leveling tool removed, it is fitted to the lower mold, An apparatus for manufacturing a grindstone for grinding and polishing, comprising: an upper mold forming a cavity for molding a grindstone between the mold and a molding surface of the mold.