JP2003170227A - Housing and method for forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for molding a housing comprising the steps of pressing a magnesium alloy plate, and molding the housing having a small size and a light weight, and further for molding a large-sized housing to obtain a sufficient strength even in the thin wall housing and omitting a post-working and having a high yield. <P>SOLUTION: The method comprises the step of pressing the magnesium alloy plate and forming the housing. Particularly, in the case of pressing, when the alloy plate is heated to 200 to 350°C, a non-bottom surface becomes slippery, and the pressing is facilitated and assured. In this heating means, a die or a die and a punch are provided and the alloy plate is heated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing such as a top cover of a hard disk drive device and a method for forming the housing.

[0002]

2. Description of the Related Art As a top cover of a hard disk drive in an electronic device, for example, a computer, a magnesium alloy injection-molded, that is, a housing molded by a so-called thixomolding method has been used.
As shown in FIG. 1, for example, a top cover as a housing of this hard disk device is composed of a cover body 1 injection-molded in the form of a rectangular container as a whole. A flange portion 2 which is joined to a housing body (not shown) and is screwed and fixed, which forms a closed case together with the cover body 1, is integrally provided on the periphery of the opening of the cover body 1. Further, a damper plate 4 is attached to the top portion (bottom portion in the figure) 3 of the cover body 1 for mainly absorbing the vibration generated around the top portion 3. The flange portion 2 has a screw hole 5
Are formed. Since the housing made of this magnesium alloy has higher thermal conductivity than resin materials such as ABS resin used as a case for ordinary electronic devices, it has excellent heat dissipation performance of heat generated in the internal drive rotation system. Since it has excellent rigidity and hardness, it has the advantages that the cover can be made thin and lightweight, and the vibration damping property is good.

A housing made of such a magnesium alloy can be formed by injection molding (Japanese Patent Laid-Open No. 200-200200).
0-213651), conventional iron, stainless steel,
Compared with a housing formed by punching a metal plate such as an aluminum alloy using a press die, it is possible to reduce the wall thickness, reduce the weight, and ensure rigidity, and omit the formation of reinforcing ribs for strengthening the strength. In terms of being able to
It has excellent practicality.

[0004]

However, the injection molding of a magnesium alloy carried out by such a conventional method of forming a top cover of a hard disk device is not suitable for forming a thin wall having a thickness of 0.5 mm or less, Further, due to the structural limitation of the injection molding apparatus, the size of large parts, for example, TV exterior parts (frames in which cathode ray tubes are fitted) is limited to 21 inches, and therefore, larger parts larger than this are the thixomolding. Molding by the method was impossible.

Further, in this thixomolding method, a fine structure of the material can be obtained because semi-melt processing is performed, but the strength is still insufficient as compared with the pressed product of the wrought material, and the molding process is performed. After that, it was necessary to perform post-processing such as surface polishing, putty filling, and deburring. The yield of the processed product by the thixomolding method is said to be about 70% at present, and it cannot be said that the moldability is necessarily excellent.

The present invention solves the above-mentioned problems, and a magnesium alloy plate can be pressed to facilitate the molding of a small-sized and lightweight housing (part) and a large-sized housing (part). It is also an object of the present invention to provide a method of forming a housing which can be molded and processed, and which has sufficient strength even if it is thin and which can omit post-processing and has a high yield.

[0007]

[Means for Solving the Problems] To achieve the above object,
The housing according to the invention of claim 1 is characterized in that a magnesium alloy plate is formed by pressing. Further, the case according to the invention of claim 2 is characterized in that the case is a lid of a hard disk drive case. With this housing, it is thin and has high strength, and it is lightweight not only for small size but also for large size. When this housing is used as a lid of a hard disk drive case, it can be made thin and have high strength, small size and light weight, and vibration damping performance can be improved.

The method of forming a housing according to the third aspect of the invention is characterized in that the housing is formed by pressing a magnesium alloy plate. As a result, it is possible to form the housing with a thin plate, the small and large housings can be formed with a light weight and high strength, and post-processing can be unnecessary.

Further, the method for forming a casing according to the invention of claim 4 is characterized in that the casing is formed by heating and pressing a magnesium alloy plate. As a result, in addition to the above, it is possible to facilitate press working that is difficult at room temperature.

Further, a method of forming a housing according to a fifth aspect of the present invention is characterized in that the housing is a lid of a hard disk drive case. As a result, the hard disk drive case can be made compact and lightweight with high strength.
Moreover, the housing itself can absorb the vibration generated during the rotation of the hard disk.

Further, the method for forming a casing according to the invention of claim 6 is characterized in that the magnesium alloy plate is heated by a heating means provided in the die of the press machine or the die and punch. By such a heating method, the magnesium alloy sheet can be heated to facilitate the press working of the magnesium alloy sheet and improve the efficiency.

Further, the method for forming a casing according to the invention of claim 7 is characterized in that the magnesium alloy plate is heated by a heating means provided in the vicinity of the die of the pressing machine.
Also by such an indirect heating method of the magnesium alloy plate, the magnesium alloy plate can be heated to facilitate the press working of the magnesium alloy plate.

According to the eighth aspect of the present invention, in the method for forming a housing, the heating temperature of the magnesium alloy plate is 200 ° C.
It is characterized in that it is set to ˜350 ° C. Since the melting point of the magnesium alloy plate is around 630 ° C, the heating temperature is 63
When the temperature is close to 0 ° C, there is a problem in the shape retention of the magnesium alloy plate, and when it is too low, it does not help to promote non-bottom slip, so the heating temperature is preferably in the range of 200 ° C to 350 ° C. Thereby, the press working of the magnesium alloy plate can be easily performed with high efficiency.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. The present invention is a method of forming a top cover as a housing in a hard disk drive device as shown in FIG. 1, for example, and a magnesium alloy plate such as AZ91 or AZ31 is used as a material for forming the top cover. This magnesium alloy plate is thin and lightweight as a whole and has good workability. For example, when used as a top cover of a 3.5-inch hard disk drive device, a plate having a thickness of 0.8 mm is prepared.

Then, the magnesium alloy plate having such a plate thickness is deep-drawn by pressing to form a cover body 1 having a flange portion 2 as shown in FIG. 1, for example. In the case of a thick wall, the magnesium alloy plate is difficult to press at room temperature because non-bottom surface slip is unlikely to occur due to its crystal structure. Therefore, at the time of press working, the die of the mold is heated to 200 ° C. to 350 ° C.
The punch is heated to a temperature of from room temperature to 70 ° C. either directly or in combination with such heating of the die of the mold. As a result, the temperature of the magnesium alloy plate can be raised to a temperature close to the temperature of the die, and plastic deformation can be easily caused, so that the press working can be smoothly and efficiently performed. Since the melting point of the magnesium alloy plate is around 630 ° C., if the heating temperature is close to 630 ° C., there is a problem in the shape retention of the magnesium alloy plate, and if it is too low, it does not help to promote non-bottom slip, so heating The temperature is preferably in the range of 200 ° C to 350 ° C.

In this case, in addition to directly heating the magnesium alloy plate with a die or punch as described above,
It may be heated indirectly by using a heating means arranged near the die, in which case it is not necessary to attach the heating means to the die or punch, and these structures are prevented from becoming complicated and expensive. it can.

Since the top cover formed in this way is a magnesium alloy plate pressed, it is possible to form a top cover having a thickness of 0.5 mm or less, which is of course small and lightweight. It also facilitates the processing of large molded products. Also, compared to the top cover injection-molded by the thixomolding method, it is thin and lightweight, yet it has sufficient strength, and although there are burrs due to pressing, it is an injection-molded product by the thixomolding method. Compared with the above, it is not a level that is practically concerned, and therefore post-processing such as deburring, polishing, and putty filling can be omitted, and a processing yield of about 100% can be secured.

When comparing the mechanical properties of the pressed product of the AZ91 magnesium alloy plate and the processed product of the conventional thixomolding method, the processed product of the thixomolding method has a yield strength (MPa) of 180.
3, tensile strength (MPa) 299.0, elongation (Φ
o) is 10.0, the pressed product has a proof stress (MPa) of 244.0 and a tensile strength (MPa) of 3
41.0 and elongation (Φo) becomes 13.0. Therefore, it is understood that the mechanical strength of the top cover processed by the press working is extremely higher than the mechanical strength of the top cover processed by the thixomolding method.

Further, since the magnesium alloy plate itself has sufficient rigidity and hardness, it has excellent vibration damping properties. Therefore, the vibration and noise generated by the rotary drive system that rotates the hard disk at a high speed between the top cover and the case can be absorbed by the top cover itself without attaching a damper plate as in the conventional case. Can also be obtained. Of course, a damper plate may be attached, and in this case the vibration damping property is further enhanced.

The magnesium alloy plate has excellent thermal conductivity and electrical characteristics, and in particular, has a thermal conductivity of about the same level as an aluminum alloy plate, and therefore the heat dissipation efficiency of heat generated in the rotary drive system of a hard disk is sufficiently enhanced. be able to. Further, although the top cover of the hard disk drive case has been described as the housing in the embodiments, the present invention is not limited to this and is applicable to all usable housings.

[0021]

As described above, according to the present invention, even if the housing is thin, the strength is high, and the housing is small and large, and lightweight. In addition, by forming a housing by pressing a magnesium alloy plate, it is possible to form a housing with a thin plate, which makes it possible to reduce the strength and size of the housing, and to reduce the size of the large-sized housing with a high strength. It can be formed, and post-processing can be omitted if necessary. Further, by heating the magnesium alloy plate and pressing it to form the casing, it is possible to facilitate pressing which is difficult at room temperature. Furthermore, by using the housing as a lid for a hard disk drive case, it is thin and lightweight, yet has high strength, and vibration that occurs during rotation of the hard disk is absorbed by the housing itself without using a vibration absorbing material such as a damper plate. Can be made.

Further, in the present invention, the magnesium alloy plate is heated by a heating means provided on a die of a press machine or a die and a punch, so that the press working of the magnesium alloy plate can be efficiently performed by such a heating method. it can. Further, by heating the magnesium alloy plate by a heating means provided in the vicinity of the die of the press machine, the press working of the magnesium alloy plate can be facilitated by such an indirect heating method of the magnesium alloy plate. . Further, by setting the heating temperature of the magnesium alloy plate to 200 ° C. to 350 ° C., non-bottom surface slip is improved, and press working of the magnesium alloy plate can be reliably performed with high efficiency.

[Brief description of drawings]

FIG. 1 is a perspective view showing a top cover of a conventional general hard disk drive device.

[Explanation of symbols]

1 Cover body as top cover of hard disk drive case

Claims (8)

[Claims] 1. A case characterized in that a magnesium alloy plate is formed by pressing. 2. The housing according to claim 1, wherein the housing is a lid of a hard disk drive case. 3. A method for forming a casing, which comprises forming the casing by pressing a magnesium alloy plate. 4. A method for forming a casing, which comprises forming a casing by heating a magnesium alloy plate and pressing the magnesium alloy plate. 5. The method for forming a housing according to claim 3, wherein the housing is a lid of a hard disk drive case. 6. The method for forming a housing according to claim 4, wherein the magnesium alloy plate is heated by a heating means provided in a die of a press machine or a die and a punch. 7. The method for forming a housing according to claim 4, wherein the magnesium alloy plate is heated by a heating means provided in the vicinity of a die of a pressing machine. 8. The heating temperature of the magnesium alloy plate is 2
The method for forming a housing according to any one of claims 4 to 7, wherein the temperature is set to 00 ° C to 350 ° C.