JPH0364491A - Surface treatment of constituent parts of magnetic disk device - Google Patents

Abstract

PURPOSE:To improve the surface cleanness of the constituent parts of a magnetic disk device by casting metal stock, forming an org. insulating coat and carrying out surface treatment by plating. CONSTITUTION:The entire surface of a base 1 made of cast metal stock is coated as the cathode by cationic electrodeposition to form an epoxy resin film 2 as an org. insulating coat in 15-30mum thickness. The faces 3, 32, 31, 33, 34 of the base 1 brought into contact with other constituent parts are then machined until the metal stock is exposed and Ni films 4 are formed on the machined faces. High dimensional accuracy and surface accuracy can be obtd.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a method for surface treatment of components in a magnetic disk device, and particularly to a structure in a magnetic disk device that requires high surface cleanliness of components. It relates to a surface treatment method for parts.

[Prior Art] In recent years, the flying spacing of magnetic heads in magnetic disk drives has been narrowing year by year to 0.5 to 0.2 μm as recording density increases, and stable flying spacing of magnetic spatulas) has become narrower year by year. To ensure this, it is necessary to maintain a high level of cleanliness inside the magnetic disk drive.

For example, it is necessary to maintain a high degree of cleanliness within the apparatus in order to prevent dust floating within the apparatus from landing on the magnetic head and impairing the flying stability of the magnetic head.

Generally, a magnetic disk drive is composed of a spindle that rotationally holds a magnetic disk, a magnetic head drive section that moves a magnetic head in the radial direction of the magnetic disk, and a base that supports the spindle and the magnetic head drive section. Many of the component parts are made of aluminum alloy material and are formed into a material shape by forging, casting, or extrusion processing, and then the parts 1 that require high dimensional accuracy that cannot be obtained with hollow molds of this material 1, such as the face of the rotating bearing of the spindle. The mounting of the magnetic head drive unit was manufactured by cutting the surface.

For example, the die-casting method for forming the material is widely used as a material manufacturing method for components of magnetic disk drives because it allows mass production of multiple shapes at low cost. Casting defects such as hot water wrinkles, hot water gaps that occur when the molten metal does not fully melt together, and slugs that occur when the mold is released, and residual aromas that adhere to the mold when the mold is released. , it was difficult to maintain stable cleanliness.

For this reason, conventional techniques include techniques in which material parts are first subjected to electrodeposition coating, and defects on the surface of the material are covered with a coating film before machining, or techniques in which only the surface that requires machining is machined and then coating accuracy is The technology used was to apply a good electroless nickel plating process and to seal the entire material surface and machined surface with a plating film.

Incidentally, examples of techniques related to surface treatment of metals include the technique described in Japanese Patent Application Laid-Open No. 63-293196.

[Problems to be Solved by the Invention] The surface treatment method according to the above-mentioned prior art is required to have even higher lnf purity with the recent increase in recording density of magnetic disk devices, and specifically, the following problems are required. There was a problem.

First, although the electrodeposited coating described above can protect most of the surface of the part, there is a large variation in film thickness accuracy, so the electrodeposited coating cannot be applied to surfaces that have been processed with high dimensional accuracy. Even if the surface was polished, there was a problem in that the surface could not be maintained with high dimensional accuracy. In addition, components coated with electrodeposited coatings can generate surface dust from the soft aluminum surface due to ``scabbing'' or ``rubbing'' with other parts during handling or assembly, and when used in magnetic disk drives, the inside of the device may be damaged. There was also the possibility of causing contamination.

On the other hand, the technology of applying an electroless nickel plating film after cutting only the surface that requires processing has the advantage of obtaining film thickness accuracy and high film hardness, but defects on the processed surface of the material may affect the quality of the protective film. The problem was that it was expensive and did not provide a high level of cleanliness.

The surface treatment method described in the above-mentioned conventional publication is aimed at the economical and design effects of surface treatment in the application fields of stationery and cosmetic packaging containers, and is intended to achieve economic and design effects due to contact with other parts. There was no mention of dust generation or dimensional accuracy.

The purpose of the present invention is to eliminate the problems caused by the prior art described above, and to improve the dimensional accuracy of each surface on which component parts are attached, and to prevent dust generation due to "galling" and "rubbing" when assembling component parts. It is an object of the present invention to provide a method for surface treatment of components in a magnetic disk device.

[Means for Solving the Problems] In order to achieve the above object, a method for surface treatment of components in a magnetic disk device according to the present invention includes a material forming process in which a metal material is finished into the shape of the component by forging, casting, and extrusion. , a painting process of painting an organic insulating film on the surface of the material finished by the material forming process, and cutting the surface of the coated moon surface that will come into contact with other components until the bare metal side is exposed. A cutting process and a plating process in which a plating film harder than the metal material is applied only to the surface cut by the cutting process are sequentially performed.

[Function] By sequentially performing each of the steps described above, the surface treatment method for components in a magnetic disk drive according to the present invention coats the surface of a metal material containing defects that cause dust with a thick organic insulating film through a coating process. By painting and applying a plating film that is harder than the metal material in the plating process after cutting the surfaces that come into contact with other components in the cutting process, each surface to which the components are attached has high dimensional accuracy and the components can be assembled. It is possible to provide a surface treatment method for components in a magnetic disk device that can prevent dust generation due to "galling" and "scratching" during time.

[Embodiment] Hereinafter, an embodiment of the surface treatment method according to the present invention will be described in detail with reference to the drawings, taking a base in a magnetic disk device as an example.

First, the surface treatment method according to this embodiment involves removing the die-cast metal material of aluminum alloy feed from the mold, cutting the sprue and riser, and casting burrs generated on the mold separation surface. is removed, and the product shape of the base 1 shown in FIG. 1 is finished.

Next, this treatment method uses the base 1, which is the object to be coated, as a cathode, and performs cationic electrodeposition coating on the entire surface of the base 1 in which the coated surface is imprinted in an electrodeposition tank and then baked (=J). As shown in Fig. 2, an epoxy resin film 2, which is an organic insulating film, is formed on the entire surface with a thickness of 15 to 30 μm.By this cationic electrodeposition coating, the base 1 is a coating film with good elution from the metal material during processing and good throwing power. can be attached to the entire surface,
Furthermore, by melting and baking the coating film, it is possible to seal in the irregularities and surface defects of the base material due to cast burr finishes, "water lines", "water marks", etc., with a smooth protective film.

Next, the bearing surface 33 attaches the spindle to the base 1 via a bearing. A horizontal plane 32 that serves as a reference for this plane 33. 3. The surface of the hole where the spindle is depressed. Surface for removing the magnetic head drive section 31. In the stator removal described later, the surface 34 is milled to high dimensional accuracy to expose the aluminum surface of these surfaces 3, 31, 32, 33, 34 as shown in FIG. This improves surface dimensional accuracy.

Thereafter, by subjecting the base 1 to an electroless nickel treatment, a nickel film 4 is formed only on the aluminum surface exposed by cutting, as shown in FIG. This nickel film treatment has a film thickness of 5 to 15 μm and a small error of 1 to 4 μm, so when a coating is applied to a surface that has been cut with high dimensional accuracy, it is possible to obtain a surface with high dimensional accuracy.

As described above, the surface treatment method according to this embodiment includes: (1) a material forming process such as removing pars from a base material that has been finished into a part shape by casting, (2) applying an epoxy resin film 2 on the entire surface of the base for 15 minutes;
Electrodeposition coating process to form a layer with a thickness of ~30μm; ■A cutting process in which the surface is cut to high dimensional accuracy by milling to attach it to other parts; ■A uniform coating thickness is applied only to the exposed aluminum surface during the cutting process. By sequentially performing the electroless nickel treatment process for forming the nickel film 4, each surface to which parts to be described later are attached can be made highly dimensionally accurate and highly hard, and dust generation can be prevented.

FIG. 5 shows a magnetic disk device assembled using the base 1 manufactured in this manner.

As shown in the figure, this magnetic disk device includes a spindle hub 7 on which a magnetic disk 10 is mounted, a spindle shaft 11 that fits into the center of the hub 7 and has a rotor 15 mounted at the bottom thereof, and the shaft Base 11 on face 3 of l
3, a magnetic head 17 supported by the head arm 8 via a gimbal 18, and a rotary rotary rotary that rotationally moves the magnetic head 17 in the radial direction of the magnetic disk 10.・Actuator 6 (
magnetic head drive mechanism) and the spindle shaft 11
It includes a stator 16 fitted to a surface 34 of the base 1 at a position facing the rotor 15 at the lower end, and a cover 9 that hermetically covers the rotary actuator 6, spindle hub 7, etc.

The rotor 5 and stator 16 constitute a rotational drive motor.

Since the magnetic head 17 seeks in the radial direction while floating a small amount on the magnetic disk 10'' by air viscous flow, it is necessary to maintain the horizontality of the magnetic disk 10 and the horizontal mobility of the magnetic head 10 with high dimensional accuracy. There is. The magnetic disk drive according to this embodiment includes two bearings 13. which rotatably hold the aforementioned rotary actuator 6 and spindle shaft 11 on the surface 33 of the base 1. The mounting surface of the stator 16 facing the rotor 15 is finished with dimensional accuracy and shape error ranging from several μm to 30 μm, which is the limit of machining. Because it is processed, each part can be assembled with high dimensional accuracy.

Also, during the assembly work in which the magnetic disk 1f supported by the rotary actuator 6 is inserted between the magnetic disks 10, the actuator 6 is mounted with a highly hard nickel-plated film so that it can be mounted smoothly on the surface 31. Since it moves while being guided, it is possible to prevent "galling" and "dust generation".

This is the same when fitting the bearing 13 and stator 16 to the base 1, and can prevent "galling" and "dust generation" between parts during assembly, and can prevent dimensional accuracy from being distorted due to "galling". can be prevented.

Furthermore, since the other surfaces of the base plate are covered with the electrodeposition coating film 2, it is possible to prevent dust from being generated on the surface due to external forces such as air currents and vibrations while the magnetic disk 10 is being rotated. can.

In addition, by preventing this "dust generation", stable cleanliness can be maintained even after long-term operation immediately after assembly, and the following effects can be expected.

(2) Surface defects during casting have little effect on the quality of the surface treatment film, and the number of castings per process can be reduced.

■ Electrodeposition coating is easy to color, so you can change the color to match the appearance of the device. For example, by making it black, the heat dissipation efficiency within the device can be improved and temperature rise can be prevented.

■ Electroless nickel plating surfaces tend to leave fingerprints when touched by human hands, potentially damaging the appearance, but since nickel plating is applied to a limited amount, handling of parts can be made easier.

In the above embodiment, an example in which surface treatment is applied only to the base member of a magnetic disk device was explained, but the present invention is not limited to this, and as shown in FIG. The outer circumferential surface 71° of the hub 7 is fitted with the inner circumference of the magnetic head 7. The linear movable carriage 60 to which the magnetic arm 8 is attached is attached to the surface 61. The surface treatment method according to the present invention may be applied to all the contact surfaces of the guide surface 62 and other components on which the carriage 60 guides the linear movement of the magnetic disk 10 in the radial direction.

Furthermore, the nickel plating process 1 2 described using FIG. 4 is not limited to electroless nickel plating.
It may also be treated with hard chrome plating.

[Effects of the Invention] As described above, according to the present invention, there are a material forming process for finishing a metal material into a part shape, a coating process for applying an organic insulating film to the surface of the material, and a process for forming an organic insulating film on the surface of the material. A cutting process in which the surface of the material that comes into contact with other components is cut until the metal material is exposed, and plating in which a plating film that is harder than the metal material is applied only to the surface cut by the cutting process. By sequentially performing the processing steps, each surface on which the component parts are attached can be made with high dimensional accuracy, and the generation of dust due to "galling" and "scratching" during the assembly of the component parts can be prevented. A surface treatment method can be provided.

[Brief explanation of drawings]

1 to 4 are diagrams for explaining a method for surface treatment of components in a magnetic disk drive according to an embodiment of the present invention, and FIG. FIG. 6 is a diagram for explaining another application example of the present invention. 1: Base, 2: Epoxy resin film, 3 Surface of spindle insertion hole, 4 Nickel film, 6: Rotary actuator, 7: Spindle hub, 8: Herad arm, 9: Cover,
lO: magnetic disk, 11 spindle shaft, 15: rotor, 16: stator, 17: magnetic head.

Claims (1)

[Claims] A method for surface treatment of components in a magnetic disk device, which includes a material forming process in which a metal material is finished into the shape of the component by forging, casting, and extrusion, and an organic insulating film is applied to the surface of the material finished in the material forming process. a cutting process in which the surface of the coated material that comes into contact with other components is cut until the metal material is exposed; and a cutting process in which the metal is applied only to the surface cut by the cutting process. A method for surface treatment of components in a magnetic disk drive, characterized by sequentially performing a plating process for applying a plating film harder than the material.