JPH06754A - Grinding method for brittle cylinder body - Google Patents

Abstract

PURPOSE:To sharply reduce the rate of occurrence of a defective product wherein crazing and a crack occur by fitting a cylinder body for reinforcement formed of a rigid material in the inner periphery of a cylinder body work to integrally form the two members with a viscous agent located therebetween and performing a grinding work in this state. CONSTITUTION:In grinding of the inner surface of a cylinder body with a thin thickness wall formed of a brittle material, a cylinder body for reinforcement formed of a rigid material being a cylinder body having an inside diameter slightly larger than the outside diameter of a cylinder body work is prepared. The cylinder body work is fitted in the cylinder body for reinforcement and the two members are integrally formed with a viscous agent located therebetween. In a state of the integrally formed substance, a grinding work is applied on the inner surface of the cylinder body work. This method causes the cylinder body for reinforcement to burden most of a holding force and a machining force generated occasioned by machining, prevents a high local force from being exerted only on the cylinder body work, and performs grinding finish of the brittle cylinder body with a high yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of grinding a brittle thin cylindrical body, which comprises grinding and finishing the inner peripheral surface or the outer peripheral surface of a thin and brittle cylindrical body made of sintered ceramic or ferrite with a grinding machine.

[0002]

2. Description of the Related Art For manufacturing a cylindrical permanent magnet used in, for example, a PM type stepping motor, there is a step of grinding and finishing the inner and outer circumferences of a ferrite cylindrical body which is formed into a cylindrical shape and sintered. Generally, the outer circumference is ground by a centerless grinder, and the inner circumference is grinded by a chuck type inner surface grinder.

[0003]

Even if a cylinder made of a brittle material such as ceramic or ferrite has a sufficiently large wall pressure, it is not so problematic. There is a problem that cracks and cracks are likely to occur in the work due to the force for holding the cylindrical work on the board and the grinding force applied to the work by the grindstone. When grinding the outer periphery of a work with a centerless grinder, the force applied to the work is easily dispersed, and the above-mentioned problem is relatively small. However, when the inner circumference of the work is ground by the cylindrical grinder, the work is easily cracked by the chucking force of the work, and the force from the grindstone is also likely to locally act. Therefore, the yield of grinding of brittle thin cylinders such as ferrite cylinders was very poor.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to make it possible to grind and finish a brittle cylindrical body with a high yield by a measure that can be easily implemented. .

[0005]

In the present invention, therefore, when grinding the inner surface of a thin-walled cylindrical body made of a brittle material, a reinforcement made of a rigid material is used as a cylindrical body having an inner diameter slightly larger than the outer diameter of the cylindrical work. A cylindrical body for use is prepared, the cylindrical work is fitted into the reinforcing cylindrical body, and a viscous agent is interposed between the two to integrate the two, and the inner surface is ground in the state of the integrated body. did. Also, when grinding the outer surface of a cylindrical work, prepare a reinforcing cylinder made of a rigid material with an outer diameter slightly smaller than the inner diameter of the cylindrical work, and apply it to the outer circumference of this reinforcing cylinder. The cylindrical work was fitted and a viscous agent was interposed between the two to integrate them, and the outer surface was ground in the state of the integrated product.

[0006]

As described above, if the cylindrical work and the reinforcing cylindrical body are fitted and integrated with each other and set in the grinder to perform the machining, most of the holding force and the machining force accompanying the machining are reduced. The reinforced cylindrical body bears the load, and no large force is locally applied only to the work.

[0007]

[Example] As an example, the grinding finish of a ferrite cylindrical body having a burned-out dimension of 51 mm outer diameter and 45 mm inner diameter will be described. With such a thickness, when the outer periphery is ground by a centerless grinder, the yield is not so bad without applying the present invention. Then, the outer circumference of the ferrite cylinder is ground by the same method as the conventional one, and the outer diameter is 50 mm and the tolerance g6 is
To finish. After that, the present invention is applied and the inner circumference is ground and finished by an inner surface grinding machine.

As a reinforcing cylinder for grinding the inner surface of the ferrite cylinder, the outer diameter is 62 mm, the inner diameter is 50 mm, and the tolerance H is H.
The stainless steel cylindrical body 7 is prepared in advance. A thickening agent such as wax is evenly applied to the inner peripheral surface of the stainless steel cylinder, and the ferrite cylindrical body whose outer periphery is ground as described above is fitted to the inner peripheral surface of the stainless steel cylinder, and both are adhered together with the wax. To be fixed integrally. The length of the stainless steel reinforcing cylinder is set to be substantially the same as that of the ferrite cylinder which is the work.

As described above, the ferrite cylindrical body is fitted into the inner periphery of the stainless steel reinforcing cylindrical body to be integrated, and the integrated product is set on the inner surface grinding machine to finish the inner surface of the ferrite cylindrical body by grinding. At this time, since the outer periphery of the integrated product is gripped by the chuck in the inner surface grinder, the work chucking force is received by the rigid stainless steel reinforcing cylinder, and a large force is not applied to the brittle ferrite cylinder. Regarding the grinding process of the inner surface of the ferrite cylindrical body of this example, the yield was about 30% by the conventional grinding method, but by applying the present invention, a yield of almost 100% was obtained.

In the above example, the reinforcing cylindrical body is not used when grinding the outer periphery of the work, but when processing a more brittle and thin cylindrical body, the reinforcing cylinder is fitted into the inner periphery of the work to be integrated, and If the outer surface is ground in the state of an integrated product, a high yield can be realized.

[0011]

As described in detail above, according to the present invention, when a thin cylindrical body made of a brittle material such as ceramic or ferrite is ground and finished, the cylindrical work is made of a rigid material on the inner or outer circumference. Since the reinforcing cylinders are fitted together and integrated with each other through the thickener, and the grinding work is performed in the state of the integrated product, most of the force applied to the integrated product during processing is the reinforcing cylinder. Since a large force is not applied locally to the brittle and thin cylindrical work piece, the incidence of defective products that cause cracks and cracks is significantly smaller than before, and highly accurate finishing can be performed with good yield. .

Claims (2)

[Claims] 1. When grinding the inner surface of a thin-walled cylindrical body made of a brittle material, a reinforcing cylindrical body made of a rigid material is prepared with an inner diameter slightly larger than the outer diameter of the cylindrical work, and this reinforcement is performed. Grinding a brittle cylindrical body, characterized in that the cylindrical work is fitted in a working cylinder, the two are integrated with a viscous agent interposed between the two, and the inner surface is ground in the state of the integrated product. Method. 2. When the outer surface of a thin-walled cylindrical body made of a brittle material is ground, a reinforcing cylindrical body made of a rigid material having an outer diameter slightly smaller than the inner diameter of the cylindrical work is prepared, and this reinforcement is performed. A brittle thin cylindrical body, characterized in that the cylindrical work is fitted to the outer periphery of the working cylinder, the viscous agent is interposed between the two to integrate the two, and the outer surface is ground in the state of the integrated product. Grinding method.