JPH1119876A - Offset type elastic grinding wheel for disk grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an offset type elastic grinding wheel for a disk grinder displaying sufficient mechanical strength and markedly improving a breaking rotational speed. SOLUTION: A substantially disk-shaped elastic grinding wheel base material 1 comprises a disk-shaped base part 2 positioned with a rotary shaft serving as the center, tapered part 3 extended in outer opened shape toward diagonally downward from a peripheral edge of this disk-shaped base part, and a doughnut disk-shaped grinding part 4 extended to an outer side in parallel to a plane formed by the disk- shaped base part from a peripheral edge of this tapered part. In an upper surface of the elastic grinding wheel base material 1, a first reinforcing member 5 of substantially circular sheet shape having a diameter larger than an external diameter of the tapered part and an external diameter or less of the elastic grinding wheel base material is bonded, in a lower surface, a second reinforcing member 6 of substantially circular sheet shape having a diameter one step smaller than an external diameter of the tapered part is bonded. In a position of a rotational center shaft of this elastic grinding wheel base material, a hole for the rotary shaft is provided, which penetrates the first reinforcing member, the disk-shaped base part and the second reinforcing member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset type elastic grinding wheel for a disk grinder, and more particularly, the present invention is applied to a disk grinder used for grinding metal, stone, glass and the like. The present invention relates to an improved offset type elastic grinding wheel, that is, a product having an improved breaking rotation speed.

[0002]

2. Description of the Related Art In general, an offset type elastic grindstone for a disc grinder is obtained by bonding an offset support base made of fiber to the back of a donut type elastic grindstone. Since the synergistic action of the elasticity of both the support base and the elastic grinding stone can be obtained, it is useful as a grinding wheel for finishing a curved surface or a finishing grinding stone.

However, this offset type elastic grinding wheel for a disc grinder has a problem that the phenomenon that the support base and the elastic grinding wheel are curved outward cannot be avoided for the following two reasons. The first reason is that
This is due to the use form of this kind of product, and the offset type elastic grinding wheel for a disc grinder is pressed against an object to be ground with a certain inclination angle so as to increase the contact area with the object to be ground. Be ground. For this,
The support base and the elastic wheel are bent outward. The second reason is that the disk grinder is used at high speed to increase the efficiency of the grinding operation. When the disc grinder is rotated at high speed, the support base and the elastic grindstone are bent outward by the action of centrifugal force, and this tendency becomes more remarkable as the rotation speed increases.

As shown in FIG. 2, a conventional offset-type elastic grindstone for a disc grinder is configured such that the inner peripheral surface of a donut flat elastic grindstone 1 'is perpendicular to a support base 5'. Therefore, as described above, when the support base and the elastic grindstone are bent outward during grinding, there are the following problems. That is, when the support base 5 ′ and the elastic grindstone 1 ′ bend outward, the inner circumference of the elastic grindstone expands, and distortion occurs at this portion. One part of the elastic wheel is compressed and another part is stretched, causing elongation strain. As a result, if the bonding between the elastic grinding stone 1 'and the support base 5' is stronger than the mechanical strength of the elastic grinding stone, the inner peripheral end 8 of the elastic grinding stone 1 'near the bonding portion between the elastic grinding stone and the support base. Destroy from. If the mechanical strength of the elastic grindstone is larger than the adhesive strength between the elastic grindstone 1 ′ and the support base 5 ′, the adhesion between the elastic grindstone and the support base may be separated, and the elastic grindstone may be broken. is there. Needless to say, such destruction of the elastic grinding stone is dangerous for the operator.

[0005] For example, Japanese Patent Publication No. Hei 6-37033 discloses a conventional offset-type elastic grinding wheel for a disc grinder which can solve the above-mentioned drawbacks.
As shown in FIG. 1, there is disclosed an elastic whetstone 1 'having a tapered portion 3' at the inner peripheral end 8 thereof. However, in the case of such an offset type elastic grinding wheel for a disc grinder shown in FIG. 3, the breaking strength of the elastic grinding wheel 1 'is increased by the tapered portion 3' provided at the inner peripheral end portion 8 of the elastic grinding wheel 1 '. Although the destruction of the elastic grindstone 1 'can be improved, there is a disadvantage that the area of the ground surface is reduced because the inner peripheral end portion 8 of the elastic grindstone 1' is tapered so as to open outward. Further, in the offset type elastic grinding wheel for a disc grinder having the structure of FIG.
However, there is also a problem that a high breaking rotation speed cannot be obtained because the bonding strength between the support base and the elastic grindstone at the inner peripheral end portion 8 is not sufficient.

[0006]

SUMMARY OF THE INVENTION The present invention improves the above-mentioned drawbacks of the conventional offset-type elastic grinding wheel for disk grinders, shows a sufficient mechanical strength without reducing the grinding area, and reduces the number of rotations at breaking. An object of the present invention is to provide a dramatically improved elastic grinding wheel. Therefore, the present inventor has conducted various studies on the fracture mechanism of the elastic grindstone, and as a result, by preventing the expansion of the inner peripheral portion of the elastic grindstone, it is possible to prevent the fracture of the elastic grindstone without changing the properties of the elastic grindstone. Based on this idea, based on this idea, the front and back surfaces of the periphery of the rotation center axis of the elastic grinding stone (periphery of the fixing hole attached to the grinder) have sufficient strength and elasticity to support the disk grinder rotating at high speed. The present invention has been completed by adopting a structure reinforced by a reinforcing member having heat resistance enough to withstand the heat generated during the grinding operation.

[0007]

That is, an offset type elastic grinding wheel for a disk grinder according to the present invention is a substantially disk-shaped offset type elastic grinding wheel used by being attached to a rotating shaft of a disk grinder. The elastic grindstone extends outwardly obliquely downward from a plane formed by the disc-shaped base from the outer peripheral edge of the disc-shaped base and the disc-shaped base positioned about the rotation axis of the elastic grindstone. A tapered portion and an elastic grindstone base material including a donut disc-shaped grinding portion extending outward from the outer peripheral edge of the tapered portion so as to be parallel to a plane formed by the disc-shaped base portion as a base material, A substantially circular sheet-shaped first reinforcing member having a diameter larger than the outer diameter of the tapered portion and equal to or less than the outer diameter of the elastic grindstone base material is bonded to an upper surface of the elastic grindstone base material, Under the whetstone substrate The, so as to cover the tapered portion and the disc-shaped base portion, substantially circular sheet-like second having a smaller diameter one size than the outer diameter of the tapered portion
A reinforcing member is adhered, and a hole for a rotating shaft penetrating the first reinforcing member, the disc-shaped base, and the second reinforcing member is provided at a position of a rotation center axis of the elastic grinding stone base material. It is characterized by the following.

Further, the present invention provides an offset type elastic grinding wheel for a disc grinder having the above-mentioned structure, wherein the first reinforcing member and the second reinforcing member cure a plain-woven glass cloth impregnated with a synthetic resin. It is characterized by being formed. Further, the present invention, in the offset type elastic grindstone for a disc grinder having the above structure, the structure of the tapered portion in the elastic grindstone base material, the structure gradually becomes dense toward the inner peripheral side,
The inner peripheral disk portion is the densest.

The structure of a preferred example of the offset type elastic grinding wheel for a disk grinder of the present invention is shown in the drawings and the present invention will be described in detail. 1 (a) to 1 (c)
FIGS. 1A and 1B are diagrams showing an embodiment of an offset type elastic grindstone for a disc grinder according to the present invention, wherein FIG. 1A is a view when viewed from above, FIG.
(C) is a diagram when viewed from below.

As shown in FIGS. 1 (a) to 1 (c), an offset type elastic grinding wheel A for a disk grinder according to the present invention is used.
The circular disk-shaped reinforcing members for improving the breaking strength are bonded to the front and back surfaces of the substantially disk-shaped offset type elastic grindstone base material 1 with the rotation center as the center. The elastic grindstone substrate 1 has a disc-shaped base 2 positioned around the rotation axis of the elastic grindstone, and a disc-shaped base And a tapered portion 3 extending obliquely downward from the outer peripheral edge of the disk base 2 and extending outward from the outer peripheral edge of the tapered portion 3 so as to be parallel to the upper and lower surfaces of the disc-shaped base 2. And a donut disk-shaped grinding portion 4. In the present invention, the first reinforcing member 5 bonded to the front surface of the elastic grindstone base material 1 and the second reinforcing member 6 bonded to the back surface are bonded to the elastic grindstone base material 1 via an adhesive, respectively. Generally, the bonding method is not limited to this. In the present invention, the inner peripheral end portion of the tapered portion 3 is generally located higher than the bonding surface of the first reinforcing member 5 to the elastic grinding stone base 1 in the grinding portion 4.

The first reinforcing member 5 and the second reinforcing member 6 in the present invention have sufficient strength and elasticity to reinforce a disk grinder rotating at a high speed, and sufficiently withstand heat generated during a grinding operation. Any material having heat resistance can be used, but in particular, a phenol resin, an epoxy resin, or the like is added to a plain woven glass cloth having a basis weight of 200 to 750 g / m ^2.
What was formed by hardening the prepreg impregnated so that it might be 85% is preferable. Such a glass cloth has a net-like structure (plain woven structure), so it is light, has strength, has elasticity and heat resistance, and is suitable as a reinforcing member. Also, like such a glass cloth, as the prepreg, carbon fiber, vinylon fiber, heat-resistant aramid fiber, and the like can be used, and the basis weight of the prepreg is 100 to 100%.
600 g / m ² is preferred. The resin amount of the prepreg may be the same as that of the glass cloth.

In the present invention, the first reinforcing member 5 and the second
As the reinforcing member 6, a fiber, a bakelite, or the like, which has been widely known as a support base of this kind of elastic grindstone for a disc grinder, may be used, or a fiber and a glass cloth may be used in combination. The term “fiber” used herein is a vulcanized fiber made of cotton or pulp, and it is also possible to use engineering plastics having properties equivalent to those of the support base material. At this time, a fiber having a thickness of 1 to 2.5 mm is appropriately used depending on the elastic whetstone substrate 1. Also, when performing grinding using the outer peripheral portion (outer peripheral end face) of the elastic grindstone base material 1 or when giving conformity (fitness to the ground surface shape of the object to be ground), the outer diameter of the elastic grindstone base material 1 Disc-shaped fibers with smaller outer diameters are used. In the present invention, the outer diameter of the elastic whetstone substrate 1 is 1
In the case of 00 mmφ, the outer diameter of the first reinforcing member 5 is 75 to
The outer diameter of the second reinforcing member 6 is generally 30 to 55 mm.

On the other hand, as the elastic grindstone base material 1 in the present invention, for example, a so-called PVA grindstone using a polyvinyl acetal resin as a binder, or a fibrous polymer short yarn to which abrasive grains are adhered or contained, and a phenol resin is used. A mixture of an elastic grindstone bonded with a hardening resin such as polyurethane resin, or a short yarn of a fibrous polymer to which an abrasive grain is attached or contained, or an attached or contained, and a natural fiber or a chemical fiber short yarn An elastic grindstone, a urethane grindstone, and the like in which are bonded with a binder.

As shown in FIG. 1 (b), the offset type elastic grinding wheel for a disc grinder according to the present invention has a disk-shaped base 2 on the inner peripheral side of the elastic grinding stone base material 1.
A tapered portion 3 that opens outward and downward from the outer peripheral edge of the tapered portion is formed.
The first reinforcing member 5 is located above the bonding surface of the elastic grinding stone substrate 1 on the grinding surface. With such a structure,
In the offset-type elastic grindstone for a disc grinder of the present invention, the strength of the inner peripheral side of the elastic grindstone base material 1 is significantly improved,
Thereby, at the time of grinding, the first reinforcing member 5 and the elastic whetstone substrate 1
Does not cause a large distortion in the inner peripheral portion, and the inner peripheral portion of the elastic grindstone substrate 1 is prevented from being broken near the bonding portion between the elastic grindstone substrate 1 and the first reinforcing member 5. In addition, the adhesion between the elastic whetstone substrate 1 and the first reinforcing member 5 is also prevented.
Further, in the offset type elastic grindstone for a disc grinder of the present invention, the presence of the tapered portion 3 increases the bonding area between the elastic grindstone base material 1 and the first reinforcing member 5, thereby increasing the mechanical strength. Since the number of rotations at break is dramatically improved as compared with the conventional elastic grindstone, and the inner and outer surfaces of the elastic grindstone base material 1 are reinforced by the first reinforcing member 5 and the second reinforcing member 6, It has higher mechanical strength.

Further, in the present invention, by forming the tapered portion 3 as shown in FIG. 1, it is possible to solve the drawback of the conventional product shown in FIG. There is also an advantage that a sufficiently large grinding area can be secured. At this time, in the present invention, the structure of the inner peripheral portion (tapered portion 3) of the elastic grinding stone base material 1 gradually becomes denser toward the inner peripheral side, and the inner peripheral end portion 8 is the densest. (In the drawings, the density of the structure is indicated by the number of points), and the elastic grinding wheel 2 having such a structure has further improved mechanical strength. Reference numeral 7 in the drawing is a rotary shaft hole for fixing the offset type elastic grindstone to the rotary shaft of the grinder.

When the tapered portion 3 as shown in FIG. 1 is formed on the inner peripheral side of the elastic grindstone base material 1, the inner peripheral surface of the elastic grindstone which is a donut-shaped flat plate having a uniform thickness is press-formed. It is common to form an offset, for example,
A method in which an adhesive is applied to both the front and back surfaces of the rotary shaft side portion of the offset type elastic grindstone base material 1 in which the tapered portion 3 is formed in advance by press molding, and the first reinforcing member 5 and the second reinforcing member 6 are respectively bonded. Apply adhesive to both front and back sides of the rotating shaft side part of the donut-shaped flat plate elastic whetstone with uniform thickness,
After the first reinforcing member 5 and the second reinforcing member 6 are respectively adhered, they are put into a press die in a state where the adhesive is not yet cured, and are pressed to form a tapered portion and at the same time, the adhesive is cured. Then, a method of integrating the first reinforcing member 5 / elastic grindstone base material 1 / second reinforcing member 6 can be used.
In addition, in the offset type elastic grindstone for a disc grinder of the present invention, when the first reinforcing member 5 and the second reinforcing member 6 are respectively bonded to the elastic grindstone substrate 1, an epoxy resin,
An adhesive such as urethane resin can be used.

An elastic grindstone substrate 1 manufactured by press-molding an elastic grindstone which is a donut-shaped flat plate having such a uniform thickness.
The tapered portion 3 has a structure in which the tissue gradually becomes denser toward the inner peripheral side, and the inner peripheral end 8 has the densest structure. The grinding part) has a density ratio of 1:
1.5 to 5 is desirable. Further, since the elastic whetstone base material 1 has a large tensile strength due to the above-mentioned structure, the number of rotations for breaking is further improved as compared with the conventional product.

FIG. 4 shows an example of a mold used for producing the offset type elastic grindstone for a disc grinder according to the present invention. 2 shows a state when the elastic grinding stone A having the structure shown in FIG. In the mold of FIG. 4, reference numeral 9 denotes an outer die, 10 denotes a tapered portion forming die, 11 denotes a cylindrical inner core, 12 denotes an inner die, and an inner die 12 in which the cylindrical inner core 11 is set. The first reinforcing member 5 is placed on the top, the donut flat elastic stone and the second reinforcing member 6 are placed on the first reinforcing member 5, and the outer die 9 and the taper forming die 10 are set. Then, the tapered portion forming die 10 is pushed into the mold to compress the inner peripheral portion of the elastic grindstone, and then cooled, to obtain the offset type elastic grindstone A having the tapered portion having a dense structure. At this time, when using a plain-woven glass cloth impregnated with the above-described resin, the glass cloth is placed on the inner mold 12 shown in FIG. 4, an elastic grindstone base material is set thereon, and the glass cloth is further placed thereon. The cloth may be placed, heated and softened, and then press-molded into an offset mold to bond the glass cloth and the elastic whetstone substrate. In the case of such a manufacturing method, the semi-cured resin impregnated in the plain woven glass cloth is completely cured at the time of press molding, and the adhesion between the glass cloth and the elastic whetstone substrate can be performed without using any special adhesive. There is an advantage that it can be performed.

[0019]

DETAILED DESCRIPTION OF THE INVENTION Polyvinyl acetal fiber (A ^#
5. Abrasive grain ratio of 150%, fiber diameter 0.31 mm, length 6.
5 mm) is impregnated with a soft polyurethane resin so that the adhesion ratio becomes 31%, and the bulk specific gravity is 0.61 g / cm.
^3. A 10 mm-thick sheet-like material (non-woven elastic whetstone) was obtained. Then, this nonwoven fabric-like elastic grindstone has an outer diameter of 101 m.
m, processed into a flat plate with an inner diameter of 15.1 mm.
A plain woven glass cloth (phenolic resin prepreg) having a diameter of 95 mm and a basis weight of 430 g / m ² is placed on the inner mold of the offset mold shown in (1), and the above-mentioned nonwoven elastic whetstone is set thereon. A glass cloth is placed, preheated at 125 ° C. for 5 minutes, and pressed at 145 ° C. so that the thickness of the polished portion becomes 8 mm.
After holding for one minute, it was cooled and worked to an outer diameter of 100 mm to obtain an offset type elastic grindstone for a disc grinder of the present invention having the structure shown in FIG. On the other hand, without using a 52 mmφ plain woven glass cloth, one having a structure in which only the upper surface of the non-woven elastic whetstone was reinforced by a 95 mmφ plain woven glass cloth was used as a comparative product. Prepare three each of the product of the present invention and the comparative product obtained by the above method,
A destructive test was performed for each product. The results are shown in the table below.

[0020]

[Table 1]

[0021]

According to the offset type elastic grinding wheel for a disc grinder of the present invention, a tapered portion is formed on the inner peripheral side of the elastic grinding stone base material so as to open outward from the disk-shaped base toward the grinding surface side. In addition, since the tapered portion and the disc-shaped base have a structure in which both front and back surfaces are reinforced by a reinforcing member, even if the elastic grindstone base material is curved outward during grinding, a large distortion is generated in the inner peripheral portion. No elastic whetstone substrate
No destruction of the inner peripheral portion of the elastic grindstone base material near the bonding portion with the reinforcing member, and no separation between the elastic grindstone base material and the first reinforcing member occurs. For this reason, the offset-type elastic grinding wheel of the present invention shows a higher breaking rotation speed than the conventional elastic grinding stone, and the mechanical strength is improved, so that the worker can perform the grinding operation with peace of mind. It is also useful for achieving increased efficiency. In the present invention, like the conventional product,
There is also an advantage that there is no reduction in the grinding area due to the formation of the tapered portion, and a sufficient grinding area can be secured.

[Brief description of the drawings]

1 (a) to 1 (c) are views showing an embodiment of an offset type elastic grinding wheel for a disc grinder according to the present invention, wherein FIG. 1 (a) is a view when viewed from above, and FIG. FIG. 3C is a longitudinal sectional view at the position of the central axis, and FIG.

FIG. 2 is a longitudinal sectional view showing one embodiment of a conventional product.

FIG. 3 is a longitudinal sectional view showing a conventional product having a sectional structure different from that of FIG. 2;

FIG. 4 is a view showing a state when the offset type elastic grindstone for the disc grinder of the present invention shown in FIG. 1 is manufactured using a press die.

[Explanation of symbols]

 A Offset type elastic grindstone for disc grinder 1 Elastic grindstone base material 1 'Elastic grindstone 2 Disc-shaped base 3, 3' taper part 4 Grinding part 5 First reinforcing member 5 'Support base 6 Second reinforcing member 7 Rotary shaft hole Reference Signs List 8 inner peripheral end 9 outer die 10 taper part forming die 11 cylindrical inner core 12 inner die

Claims (3)

[Claims] 1. A substantially disk-shaped offset type elastic grinding wheel used by being attached to a rotating shaft of a disk grinder, wherein said elastic grinding wheel is located around a rotating shaft of said elastic grinding wheel. A tapered portion extending outward from the outer peripheral edge of the disc-shaped base obliquely downward from a plane formed by the disc-shaped base; and a plane formed by the disc-shaped base from the outer peripheral edge of the tapered portion. The base is an elastic grindstone base made of a donut disk-shaped grinding portion extending outward so as to be parallel to the upper surface of the elastic grindstone base, which is larger than the outer diameter of the tapered portion. A substantially circular sheet-shaped first reinforcing member having a diameter equal to or less than the outer diameter of the elastic grindstone base material is adhered, and the lower surface of the elastic grindstone base material covers the disc-shaped base and the tapered portion. To the outer diameter of the tapered portion. A substantially circular sheet-like second reinforcing member having a small diameter around the first and second reinforcing members is adhered, and the first reinforcing member, the disc-shaped base, and the second (2) An offset type elastic grindstone for a disc grinder, wherein a hole for a rotating shaft penetrating through the reinforcing member is provided. 2. The disk grinder according to claim 1, wherein the first reinforcing member and the second reinforcing member are formed by curing a plain-woven glass cloth impregnated with a synthetic resin. Offset type elastic whetstone. 3. The structure of the tapered portion of the elastic whetstone base material gradually becomes denser toward the inner peripheral side, and the inner peripheral disk portion is the densest. 2. The offset type elastic grindstone for a disc grinder according to 2.