JPH0753348B2 - Polishing wheel for composite materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention mainly relates to a permanent magnet type erasing head and is a product having a structure in which a sintered ferrite magnet is embedded in a resin case, which is made of a hard material and a viscous and soft material. The present invention relates to a polishing grindstone for a composite material, which is used for efficiently polishing different kinds of materials at the same time.

2. Description of the Related Art A permanent magnet type erasing head has a structure in which a sintered ferrite magnet 5 is inserted and fixed in a resin case body 4, as shown in the front view of FIG. 3a and the side view of b.
As shown in the figure, the product was pressed against the outer peripheral portion of the polishing grindstone 6 that rotated, and a predetermined angle R was repeated to form a predetermined R to finish the tape sliding surface. The polishing grindstone 6 is generally called a "green silicon carbide resin bond grindstone", and as shown in FIG. 5, green silicon carbide abrasive grains 8 having an average particle diameter of 28 to 40 μ are used in a volume ratio. The ratio was about 40%, the binder 9 made of a thermosetting resin such as phenol resin was about 20%, and the balance was composed of pores 10.

Problems to be Solved by the Invention However, the conventional grinding wheel 6 does not have a composition content suitable for simultaneous polishing of different materials, and as a result, as shown in FIG. 11 occurred and the amount reached 5 to 10 μ, which deteriorated the product characteristics. Although this phenomenon is suitable for polishing the sintered ferrite magnet 5, the polishing grindstone 6 used is not suitable for polishing the resin material. Therefore, the polishing powder of the sintered ferrite magnet 5 is not suitable for the resin case body 4. Since it becomes sticky when mixed with the polishing powder of No. 3, and adheres to the surface of the polishing wheel 6, the polishing ability of the polishing wheel 6 decreases as the polishing progresses, and the resin case body 4 is not polished more and more. Then, the grinding wheel 6 is pressed. As shown in FIG. 7, the product is gradually fed in the circumferential direction of the grinding wheel 6 for finishing to a predetermined R shape and overall height, but the sintered ferrite magnet 5 was ground and fed. Although it is processed by the amount, the resin case body 4 is hard to be polished, and is compressed and elastically deformed as shown by 12 in the figure. When the product is taken out after the polishing process, the resin case body 4 which has been elastically deformed as shown in FIG. 8 is restored to some extent because the pressing force disappears. This phenomenon is manifested as the interface step 11 between different kinds of materials described above with reference to FIG.
There was a big problem in terms of quality. The present invention is intended to solve the above-mentioned drawbacks of the conventional example and to provide a polishing grindstone for a composite material capable of obtaining a product of stable quality.

Means for Solving the Problems In order to solve the above problems, the present invention reduces the average particle diameter of the green silicon carbide abrasive grains to 16 to 28 μ and the amount of the abrasive grains in a volume ratio of 35 to 40%, Porosity 40
-50%, with the balance being a binder.

Operation With the above configuration, even when the permanent magnet type erasing head is polished, stable polishing can be performed without significantly lowering the polishing ability, and the interface step between different materials is improved and stabilized. It is possible to obtain quality products.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The following table shows the content of the polishing grindstone for composite materials in terms of volume ratio, and a typical one of the conventional products and one used in the examples of the present invention are compared. It can be seen that the average particle size was smaller and the porosity was larger in the case of.

Although the average abrasive grain ratio is reduced by the increase in the porosity, the actual number of abrasive grains is unchanged or tends to increase because the average particle diameter is reduced. When the average particle diameter of the conventional product is assumed to be 28 μ when the abrasive grains are assumed to be spherical, the number of abrasive grains in Example 20μ of the present invention is about 2.4 times, and the average particle size of the conventional product is 40 times.
The number of abrasive grains in the case of trial calculation with μ is about 7 times. When the diameter of the abrasive grains becomes smaller, the polishing capacity per abrasive grain decreases, but since the number of abrasive grains is large, more abrasive grains come into contact with the product to be polished, and as a result, the polishing efficiency is increased. Will improve.

FIG. 1 shows the structure of a polishing wheel for composite materials according to the present invention,
Green Silicon Carbide Abrasive Grain 1 with an average particle size of 20μ
Is fixed with a binder 2 composed of a phenol resin, and the binder 2
A large number of pores 3 are formed inside the. For the polishing process, the symbol "processed surface" in the figure is used, and the surface is brought into contact with the object to be processed. FIG. 2 is a further enlarged view of FIG. 1, in which pores 3 are present inside the binder 2 to which the green silicon carbide abrasive grains 1 are fixed. It should be noted here that the number of pores 3 is increased, so that the pores 3 also appear on the grindstone processing surface (surface). The polishing powder generated by the polishing process adheres to the surface of the grindstone, but since there are many pores 3, the amount of particles that temporarily fall into the pores 3 increases, and the adhesion to the surface of the grindstone significantly decreases. Polishing work is No. 7 of the conventional example
As described with reference to the figure, since processing is performed while moving in the left-right direction with respect to the object to be polished, the polishing powder temporarily dropped into the pores 3 is It is washed away by the cooling water which is constantly sprayed, and the progress of the adhesion of the polishing powder to the surface of the grindstone can be efficiently prevented.

Effects of the Invention As described above, in the present invention, it is possible to provide a large number of pores and efficiently prevent the adhesion of polishing powder, and the abrasive grain ratio is decreased by the amount of increased porosity, but the average of the abrasive grains By reducing the particle size, the number of abrasive grains can be increased, and the polishing efficiency can be equal to or higher than the conventional efficiency, which is a high contribution.

[Brief description of drawings]

1 and 2 are sectional views showing the structure of a polishing grindstone for a composite material according to an embodiment of the present invention, FIGS. 3 to 8 show a conventional example, and FIGS. 3a and 3b are permanent magnet types. The structure of the erasing head is a front view and a side view, FIG. 4 is an explanatory view showing the principle of R polishing of the tape sliding surface, and FIG. 5 is a sectional view showing the structure of a conventional grindstone.
FIG. 6 is an explanatory view showing a state where a boundary surface step is generated between different materials of a permanent magnet type erasing head, FIG. 7 is an explanatory view showing a relationship between a grindstone and an object to be polished in a polishing process step, and FIG. FIG. 4 is an explanatory diagram showing a situation of occurrence of a boundary surface step. 1 ... Green silicon abrasive grains, 2 ... bonding agent, 3 ... pores.

Claims (1)

[Claims] 1. A polishing grindstone for a composite material, which polishes a composite material comprising a magnetic material and a resin, wherein green silicon carbide abrasive grains having an average particle diameter of 16 to 28 μ are used, and the abrasive grain ratio is 35 by volume. -40%, porosity is also 40-50%, and the rest is a grinding wheel for composites made of a binder made of thermosetting resin.