JPH059227B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a wrapping method for a composite material made of two or more materials, such as a magnetic head. [Prior Art] Wrapping is usually used to finish high-precision parts such as magnetic heads. Composite materials made of different materials with different hardnesses are used in the magnetic head, but in the past, no consideration was given to the differences in processing amount caused by the differences in workability of each material, so-called processing steps. For example, in a magnetic head, if the magnetic material is recessed relative to other materials, the distance from the magnetic medium increases and the electrical characteristics deteriorate. For this reason, it is necessary to make the processing step difference as small as possible. As described above, in the wrapping process of composite materials, it is required to process the processed surface with high shape accuracy over a long period of time, and to process the surface roughness and processing steps with high precision. Furthermore, when wrapping a composite material made of different materials having different hardnesses, the shape of the wrapping plate is transferred to the workpiece, so it is necessary to maintain the shape of the wrapping plate with high precision. However, in lapping processing, when processing a workpiece, abrasive grains are interposed between the lapping surface plate and the workpiece, and the lapping surface plate is moved relative to the workpiece under constant pressure, so that the lapping surface plate is also ground together with the workpiece. For this reason, as the machining time (number of pieces to be machined) increases, the shape of the lap surface plate deteriorates and the shape of the workpiece also falls. In order to prevent deterioration of the shape of the workpiece, it is necessary to periodically correct the shape of the lap surface plate. Conventionally, a lap surface plate made of soft metal was used, but because it is soft, it is difficult to handle and easily scratches, and the amount of wear on the lap surface plate is large compared to the amount of workpiece processed. The disadvantage was that the shape deterioration was significant and the shape correction cycle was short. [Problems to be Solved by the Invention] An object of the present invention is to provide a method for wrapping a composite material with small processing steps. [Means for solving the problem] A composite material consisting of two or more different materials, at least one of which is ceramic, is made of alumina as a main component, and abrasive grains are inserted so that the bulk specific gravity is 3.4 to 3.8. The process is characterized in that the processing steps are reduced by lapping with a lapping surface plate in which holes are evenly distributed. [Effect] Fine abrasive grains enter and are held in the pores uniformly distributed on the lap surface plate, so relatively soft materials are quickly polished by the abrasive particles scattered on the surface plate. This prevents machining steps and also prevents surface plate wear. [Example] Specific examples of the present invention will be described with reference to the drawings. (Example 1) When processing a composite material in which the processing sample is made of two or more different materials, a difference in level occurs due to the difference in workability between the materials. For example, very hard materials such as titanium carbon-based alumina ceramic materials (Vickers hardness Hv≒2000) and permalloy (Hv≒1500)
When processing a material made of a soft material such as, a step occurs. Table 1 shows the relationship between the bulk specific gravity of the alumina ceramic surface plate and the processing step. When machining is performed using a lap surface plate with a bulk specific gravity of 3.9 and a high alumina content, the machining level difference is large, from 0.05 to 0.05.
It was 0.07μm. Additives such as carbon are evenly mixed into alumina, which is the main component of the surface plate, to lower the alumina content and create holes on the surface plate that are large enough to allow the abrasive grains, which are fine powder, to enter. Evenly distributed. As the number of holes evenly distributed on this surface plate increases, the processing step becomes smaller and the bulk specific gravity becomes smaller.
It becomes minimum near 3.55. If it is made even smaller, the evenly distributed holes will interfere with each other, so the level difference will become larger. In the case of a floating magnetic head for a magnetic disk device that reads and writes while maintaining a minute gap, if the processing step is large, the electrical characteristics will deteriorate, so it is necessary to keep the gap to 0.05 to 0.06 μm or less. From the above results, the optimum bulk specific gravity range is 3.4 to 3.8.

[Table] Table 2 shows a comparison of the processing characteristics of tin and alumina ceramic as lap surface plate materials. The processed sample is
It is made of carbon-based alumina ceramic material, and the lap abrasive grains are made of diamond powder. The roughness of the machined surface is 0.01μmRmax for tin lap, while it is 0.015μRmax for alumina ceramic material.
There is not much difference in machining efficiency and machined surface shape. However, the life of the lap surface plate is limited by the straightness of the machined surface of 0.05μm/
Defining and comparing the number of processed parts satisfying 4nm, tin wraps have 100 to 200 parts, while alumina ceramics have more than 400 parts, which can be used for more than twice as long.

[Table] (Example 2) Using the alumina ceramic material of Example 1 with a bulk specific gravity of 3.55, a lap surface plate shown in FIG. 1 was created. In Fig. 1, 1 is the part on the lap surface plate;
The a-side is a lapped surface and is created by a method such as casting. 2 is a lower part of the lap surface plate; 3 is a groove for guiding fluid for cooling or heating;
It is made using methods such as the Doshoho method. 4 is a fluid inlet;
5 is a fluid discharge port, and 1 and 2 are integrated by molding and joining. As a result of processing a material composed of titania-based alumina ceramic material (Hv≒1200) and permalloy using diamond abrasive grains using this lap,
At room temperature (approximately 20℃), the machining step is 0.09μm, but as a result of cooling the lap surface plate to 5℃ or less, the machining step can be reduced to 0.03μm or less, and the cooling groove has a cooling effect. I understood. Furthermore, the flatness of the machined surface was good at 0.03 μm/4 mm, and it was found that there was little deformation of the lap surface plate due to temperature changes. Bulk specific gravity of alumina ceramic surface plate is 3.4 to 3.8
It is clear that within the range of , the same effects as described above can be obtained. In addition, even composite materials made of two or more different materials with a Vickers hardness ratio of around 13 times, such as the combination of titanium carbon-based alumina ceramic material and permalloy used in Example 1, and the combination of zirconia-based ceramics and permalloy, can be processed. It is clear that the effect of reducing the level difference can be obtained. [Effects of the Invention] According to the present invention, in lapping processing of composite materials made of different materials with different hardnesses, the rate of shape deterioration of the surface plate is reduced compared to the current wrapping, and high precision processing can be performed for a long period of time. There is. moreover,
Because it is hard, it is difficult to get scratches during handling, and it is also recognized to improve workability. In addition, the deformation of the lapping surface plate due to cooling and heating is extremely small because it is made of the same material, making it easy to manage the lapping surface plate, and enabling high-precision processing with good reproducibility in wrapping processing of composite materials. effective.

[Brief explanation of the drawing]

In FIG. 1, a and b are plane and front sectional views of the lap surface plate. Explanation of symbols: 3...Fluid guide groove, 4, 5...Fluid introduction, discharge port.

Claims (1)

[Scope of Claims] 1. A composite material consisting of two or more different materials, at least one of which is ceramic, is made of alumina as a main component, and is made of a material having a bulk density of 3.4 to 3.8. A method for wrapping a composite material, which is characterized by wrapping using a wrapping surface plate with uniformly distributed holes. 2. The method for wrapping a composite material according to claim 1, wherein grooves for guiding fluid are provided in the wrapping surface plate, and the wrapping is performed while cooling.