JPH052469B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an offset type elastic grindstone for a disk grinder and a method for manufacturing the same.
More specifically, the present invention relates to an improved offset-type elastic grindstone that is attached to a disc grinder used for grinding metal, stone, glass, etc., and a method for manufacturing the same. [Conventional technology and its problems] Conventional offset-type elastic grinding wheels for disk grinders generally have an offset-type support base made of vulcanized fibers (hereinafter simply referred to as "fibers") glued to the back of the elastic grinding wheel. It is true. Fibers are used as support bases not only because they are cheaper than other support bases, but also because they provide a good feel. In other words, the support base made of fiber has softer contact with the object to be ground during use, compared to support bases made of other materials. By the way, in the conventional product, since the elastic grindstone 1' and the support base 2' have the same outer diameter (see FIG. 3), the following problems occurred.
An offset type elastic grindstone for a disk grinder is used by being pressed against the object to be ground at a certain angle of inclination. Therefore, the wear of the elastic grindstone progresses from the grinding surface side to the adhesive surface side with the support base, but the wear of the elastic grindstone progresses particularly violently at the outer peripheral portion. Eventually, his support base was exposed. This support base is made of fibers that are harder than the elastic whetstone and do not have abrasive properties, so when this support base hits the object to be ground, even though the elastic whetstone still remains on the inner periphery, the disk grinder It was becoming impossible to use it as an offset type elastic grindstone. In order to eliminate these drawbacks, elastic grinding wheels with an outer diameter larger than that of the support base, in other words, those in which the outer periphery of the elastic grindstone is not supported by the support base, have been invented. It is used. However, elastic grindstones that originally have good grinding performance are not very strong in terms of strength. Therefore, under severe grinding conditions, there was a risk that the outer circumferential portion made only of the elastic grinding wheel, which had become thin due to wear, would break and be scattered.
Therefore, such offset-type elastic grindstones for disk grinders are not widely used because they lack safety. Furthermore, a method using a resinoid grindstone having the same outer diameter as the elastic grindstone as a support base has been devised (see Japanese Utility Model Application Publication No. 183159/1983). In this offset type elastic grindstone for a disk grinder, when the outer circumferential portion of the elastic grindstone is worn out, the resinoid grindstone serving as a support base is also worn away, so that it is possible to use up to the inner circumferential portion of the elastic grindstone. However, since the resinoid grindstone is harder than the fiber, the elasticity of the elastic grindstone is suppressed by the hardness of the resinoid grindstone. Therefore,
There was a problem in that it did not provide a good feeling of use like an elastic grindstone that uses fibers as a support base. Further, in order to obtain this offset type elastic grindstone for a disk grinder, the following problems occurred in the manufacturing method. That is, since the resinoid grindstone and the elastic grindstone are completely different, they must be manufactured separately and then bonded together. Therefore, there was a problem in that manufacturing thereof required extremely labor and time. [Means for Solving the Problems] As a result of various studies in view of the problems of the conventional products, the present inventor has developed an elastic grinding wheel by using fiber or something similar in strength, elasticity, and heat resistance as a support base. The idea was to hold the elastic grindstone in the same way as a supporting base until the outer circumference of the elastic grindstone wears out, and then provide an auxiliary grindstone that itself wears out as the elastic grindstone wears out. Through further research based on this idea, we succeeded in obtaining an offset-type elastic grindstone for disc grinders according to the present invention, which has a long product life, is safe, and has a good feeling of use. That is, the offset-type elastic grindstone for a disk grinder according to the present invention has an outer diameter smaller than the outer diameter of the main grindstone 1 and an offset portion in the center. A ring-shaped auxiliary whetstone 3, which has inferior grinding performance but superior mechanical strength than the main whetstone 1, is integrally provided on the lower surface of the support base 2 and the support base 2. A ring-shaped main grindstone 1 is provided on the lower surface of the auxiliary grindstone 3 provided from the support base 2 to the outer periphery thereof, excluding the offset portion. It is something. Further, the method for manufacturing an offset-type elastic grindstone for a disk grinder according to the present invention includes a cylindrical shape having a depression having the same shape as the offset part of the offset-type support base 2 at the center of the bottom surface and having an inner diameter that is the same as the outer diameter of the main grindstone 1. An offset-type support base is placed on the bottom of the outer mold, and a cylindrical inner mold that closes the offset portion of the support base is set in the center thereof, and the bottom or the outer mold is placed on the outer mold of the outer periphery of the support base. The auxiliary whetstone 3 is attached to the bottom of the support base 2 and the top of the support base 2.
At the same time, a constant thickness of raw material for the main grindstone, which has lower mechanical strength than the auxiliary grindstone but has superior grinding performance, is loaded into the ring-shaped space formed by the inner mold and the outer mold, and then It is characterized by applying pressure under heat using a ring-shaped pressure mold. The main grindstone 1 used in the present invention is an elastic grindstone, and the elastic grindstone referred to in the present invention requires support by a support base when used as an offset type elastic grindstone for a disk grinder. As such an elastic grindstone, for example, a so-called so-called grindstone using polyvinyl acetal resin as a binder is used.
Examples include a PVA grindstone, and a grindstone in which short threads of fibrous polymer to which abrasive grains are attached or contained are bonded with a hardening resin such as phenol resin. The support base 2 used in the present invention can be made of fiber, Bakelite, or other materials that have strength, elasticity, and heat resistance equivalent to these materials. Fibers are obtained by soaking cotton or pulp fibers in an aqueous zinc chloride solution, coagulating them, and pressing them into a cardboard-like form, and are widely used as this type of support base. The support base 2 used in the present invention has an outer diameter smaller than the outer diameter of the main grindstone 1. For example, when an offset type elastic grindstone for a disk grinder has a thickness of 7 mm and an outer diameter of about 100 mm, the diameter of the support base may be set to about 80 mm to 90 mm. As the auxiliary grindstone 3 used in the present invention, an elastic grindstone having better mechanical strength than the main grindstone 1 is used. A grindstone with such performance can be obtained by changing the type, blending ratio, or bulk specific gravity of the binder and abrasive grains used in the main grindstone 1. This auxiliary grindstone 3 has the same outer diameter as the main grindstone 1 and forms the outer edge of the support base 2. Here, the meaning that the auxiliary whetstone 3 forms the outer edge of the support base 2 refers not only to the case where the auxiliary whetstone 3 is present only on the outer periphery of the support base 2 (see Figure 1), but also to the case where the auxiliary whetstone 3 forms the outer edge of the support base 2. 2
This includes not only the outer periphery of the support base 2 but also the entire surface of the support base 2 (see FIG. 2). In addition, in FIGS. 1 to 3, A-A indicates an example of the maximum grinding limit line. Next, the manufacturing method of the present invention will be explained. The offset type support base is placed on the bottom of a cylindrical outer mold which has a recess in the center of the bottom surface having the same shape as the offset part of the offset type support base 2 and has an inner diameter that is the same as the outer diameter of the main grindstone 1. Next, a cylindrical inner mold that closes the offset portion of the support base is set in the center thereof,
The raw material for the auxiliary grindstone 3 is loaded onto the outer mold and the bottom of the outer periphery of the support base, or the bottom of the outer mold and the upper surface of the support base 2. Next, a constant thickness of the raw material for the main grindstone is loaded into the ring-shaped space formed by the inner mold and the outer mold, and a ring-shaped pressure mold is fitted over it, and pressurized under heating to create an offset-type elastic disc grinder. A whetstone is obtained. In addition, at the stage when the raw material for the auxiliary whetstone is put in, the support base and the auxiliary whetstone are integrally attached by applying pressure under heat, and then the raw material for the main whetstone, which has better grinding performance than the auxiliary whetstone, is put into the mold, and then again. The supporting base, the auxiliary grindstone, and the main grindstone may be integrally attached by applying pressure under heat. However, after putting the raw material for the auxiliary whetstone into the gap between the inner wall of the mold and the outer periphery of the support base, it is preferable to immediately put the raw material for the main whetstone, which has better grinding performance than the auxiliary whetstone, and then pressurize it under heat. . This is because by doing so, the connection between the support base, the auxiliary grindstone, and the main grindstone can be made stronger. Additionally, the raw material for the main grindstone described above may be a molded product. However, in this case, it goes without saying that an adhesive layer must be interposed between the main grindstone and the support base in order to integrate the grindstone with the support base. Regarding the relationship between the main whetstone and the auxiliary whetstone, the main whetstone has better grinding performance than the auxiliary whetstone but has inferior mechanical strength, and the auxiliary whetstone conversely has better mechanical strength than the main whetstone. However, the grinding performance is inferior. [Function] In the offset type elastic grindstone for a disk grinder according to the present invention, as the main grindstone wears down, the object to be ground hits the auxiliary grindstone before hitting the support base. Since this auxiliary grindstone can be worn out, the wear of the auxiliary grindstone also progresses as the main grindstone wears out. Therefore, with the offset type elastic grindstone for a disk grinder according to the present invention, the grinding operation can be continued until the auxiliary grindstone is completely worn out and the object to be ground hits the support base. [Example] A fiber offset type support base 2 with an outer diameter of 90 mm was loaded into an outer mold having an inner diameter of 100 mm and a recess at the center of the bottom so that the offset portion thereof matched with the recess. Thereafter, an inner mold with an outer diameter of 54 mm was set on the inner surface of the offset part. Next, a C is placed at the bottom of the outer mold between the inner wall of the outer mold and the outer periphery of the fiber.
A raw material for an auxiliary grindstone consisting of a blend of 5.5 g of #220 abrasive grains, 1.5 g of polyvinyl acetal resin, and 2.1 g of phenolic resin was added. After that, a short thread of polyvinyl acetal fiber containing about 70% of C# 60 abrasive grains is inserted into the ring-shaped space formed by the inner mold and the outer mold.
A raw material for the main grindstone consisting of a mixture of 35.5 g and 8.5 g of phenolic resin was placed, a ring-shaped pressure mold was fitted into the ring-shaped space, and pressure was applied at 150° C. for 30 minutes. As a result, an offset type elastic grindstone for a disk grinder was obtained, in which a main grindstone with a thickness of 7 mm was integrally adhesively supported by fibers and an auxiliary grindstone. A grinding experiment was conducted using the offset type elastic grindstone for a disk grinder thus obtained. The volume of the main grindstone that is worn out until the fiber hits the object to be ground was investigated while changing the contact angle θ between the main grindstone and the object to be ground. The results are shown in Table 1. [Comparative Example] For comparison, an offset-type elastic grinding wheel for a disc grinder was prepared by bonding an elastic grinding wheel with an outer diameter of 100 mm made of the same compound as the main grindstone of the above example and fibers with an outer diameter of 100 mm. Grinding experiments were conducted in the same manner. The results are also shown in Table 1.

〔Effect of the invention〕

Since the present invention has the above configuration, the following effects can be obtained. That is, in the offset type elastic grindstone for a disc grinder according to the present invention, the outer diameter of the support base is smaller than the outer diameter of the main grindstone, and the auxiliary grindstone, which can wear itself, is provided on the outer periphery of the support base. The main grindstone can be used until the grindstone is worn out. In addition, since the outer peripheral part of the main grindstone is made up of an auxiliary grindstone with excellent mechanical strength, the work can be carried out safely without breaking or scattering. Furthermore, since an elastic material such as fiber is used as the support base, a good feeling of use can be obtained. Further, the offset type elastic grindstone for a disk grinder according to the present invention can be manufactured using a process that is almost the same as that of conventional products in which the main grindstone and the support base have the same outer diameter.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing one embodiment of an offset type elastic grindstone for a disk grinder according to the present invention, Fig. 2 is a longitudinal sectional view showing another embodiment, and Fig. 3 is an embodiment of a conventional product. FIG. In the figure, 1...Main grindstone, 2...Support base, 3...
...Auxiliary whetstone.

Claims (1)

[Scope of Claims] 1. The outer periphery of an offset-type support base 2 having an outer diameter smaller than the outer diameter of the main grindstone 1 and having an offset portion in the center, or the outer periphery of the support base 2 and the lower surface of the support base 2 A ring-shaped auxiliary grindstone 3 having inferior grinding performance but superior mechanical strength than the main grindstone 1 is integrally provided, and the lower surface of the auxiliary grindstone 3 on the lower surface of the support base 2 and the outer periphery thereof or the support base 2 An offset-type elastic grindstone for a disk grinder, characterized in that a ring-shaped main grindstone 1 is provided on the lower surface of an auxiliary grindstone 3 provided over the outer periphery of the auxiliary grindstone 3, excluding the offset portion, up to the outer periphery of the auxiliary grindstone 3. . 2. An offset-type support base is placed on the bottom of a cylindrical outer mold that has a recess in the center of the bottom that has the same shape as the offset part of the offset-type support base 2 and has an inner diameter that is the same as the outer diameter of the main grindstone 1. A cylindrical inner mold that closes the offset portion of the support base is set in the support base, and the raw material for the auxiliary grindstone 3 is loaded on the bottom of the outer mold on the outer periphery of the support base or on the bottom of the outer mold and the top surface of the support base 2. At the same time, a ring-shaped space formed by the inner mold and the outer mold is loaded with a constant thickness of raw material for the main grindstone, which has lower mechanical strength than the auxiliary grindstone but has superior grinding performance, and a ring-shaped pressure mold is inserted from above. A method for manufacturing an offset type elastic grindstone for a disc grinder, which is characterized by pressurizing it under heat.