JPH03272062A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To decrease the thermal off-track by executing force-fitting or shrinkage fitting of a member whose thermal expansion coefficient is in the middle of a thermal expansion coefficient of a housing and a thermal expansion coefficient of a shaft between the housing and the shaft. CONSTITUTION:Between a housing 13 on which a magnetic disk or a magnetic head arm is loaded and a shaft 14 to which the housing is subjected to force- fitting or shrinkage fitting, a member 20 whose thermal expansion coefficient is in the middle of the thermal expansion coefficient of the housing 13 and the thermal expansion coefficient of the shaft 14 is subjected to force-fitting or shrinkage fitting. Accordingly, a thermal stress generated by a temperature rise of the inside of a magnetic disk device can be dispersed along the axial direction of a carriage shaft 14. In such a way, the thermal off-track can be decreased.

Description

[Detailed Description of the Invention] [Summary] A magnetic disk device having a housing in which a magnetic disk disk or a magnetic head arm is mounted, and a shaft into which the housing is press-fitted or shrink-fitted, and which reduces thermal off-trunk. A member having a coefficient of thermal expansion located between the coefficient of thermal expansion of the housing and the coefficient of thermal expansion of the shaft is press-fitted or shrink-fitted between the housing and the shaft.

[Industrial application field]

The present invention relates to a magnetic disk device having a housing on which a magnetic disk PI plate or a magnetic head arm is mounted, and a shirt onto which the housing is press-fitted or shrink-fitted.

In recent years, magnetic disk drives have been trending toward higher density and larger capacity, and along with this, the track pinch has become higher density and the capacity per trunk has increased, causing misalignment between the data head and servo head (off-trunk). It is necessary to reduce the number of

(Prior Art) FIG. 3 is a diagram showing the configuration of a conventional magnetic disk device.

In the figure, a plurality of magnetic disk circles Fi5 are held in a spindle housing 3 via spacers, and are fixed to a spindle 4 with screws via a presser member. This spindle housing 3 is fastened to a spindle 4 rotatably supported on a base 1 by spindle bearings 2a, 2b by press fit or shrink fit. The spindle 4 is rotatably driven by a spindle motor 6.

Further, the magnetic heads 11 are attached to the upper and lower sides of the magnetic head arm 12, respectively. The magnetic head arm 12 is fixed to a housing 13 of a magnetic head. The housing 13 is fastened to the carriage shaft 14 by press fit or shrink fit. The magnetic head press is rotationally driven by a voice coil motor 9. The carriage shaft 14 is rotatably held by bearings 8a and 8b provided on the base l and a flange 15 provided on the base l. Incidentally, the lid 10 covers the magnetic disk 5 and the center of the magnetic handshake. Here, the housing 13 is made of a material such as magnesium or aluminum, and the carriage shaft 14 is made of 5O34.
16 grade material is used.

[Invention tries to solve it! ! ! ! ! ! ! l) However, since it is very difficult to manufacture the inner diameter of the housing 13 and the outer diameter of the carriage shaft 14 so that they are perfectly circular, when the housing 13 and the carriage shaft 14 are press-fitted or shrink-fitted, , it is not possible to fit them together with uniform pressure along the axial direction of the carriage shaft 14.

Therefore, when the housing 13 and the carriage shaft 14 thermally expand as the temperature inside the magnetic disk device increases, thermal stress is generated due to the difference in coefficient of thermal expansion between the two, but the magnitude of this thermal stress is However, due to the non-uniformity of the fitting pressure distribution described above, there is a problem in that the fitting pressure varies along the axial direction of the carriage shaft 14, resulting in thermal off-track.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide a magnetic disk device in which thermal off-track does not occur.

[Means to solve the problem]

According to the present invention, this object is achieved by providing a housing on which a magnetic disk disk or a magnetic head arm is mounted, a shaft to which the housing is press-fitted or shrink-fitted, and a housing between the housing and the shaft. press-fitting or shrink-fitting a member whose thermal expansion coefficient is located between the thermal expansion coefficient of the housing and the thermal expansion coefficient of the shaft;
This is achieved by providing a magnetic disk device characterized by the following.

[Effect]

That is, the present invention focuses on the fact that variations in the magnitude of thermal stress are caused by variations in the fitting pressure between the housing and the shaft, and the coefficient of thermal expansion thereof is determined to be between the coefficients of thermal expansion of the housing and the shaft. By press-fitting or shrink-fitting the member located between the housing and the shaft, thermal stress between the intermediate member and the shaft and between the intermediate member and the housing can be reduced, and the location where thermal stress occurs can be reduced. By making the distances different, the amount of displacement throughout the shaft is made uniform, and a thermal off-track is pasted.

[Example] Hereinafter, an example of a magnetic disk device according to the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram of one embodiment, and in the figure, the same parts as in FIG.
is an intermediate member, for example, the coefficient of thermal expansion is 17X10-
The carriage shaft 14 is press-fitted or shrink-fitted into the carriage shaft 14, which is made of a material such as 5US3035US304 with a coefficient of thermal expansion of 11 x 10-', such as 5US416, and is made of a material such as aluminum or magnesium alloy Housing 1 with a coefficient of thermal expansion of 24XIO-'
3 is press-fitted or fired into this intermediate member 20.

With this configuration, it is possible to disperse thermal stress caused by a temperature rise inside the magnetic disk device along the axial direction of the carriage shaft 14.
For example, as a result of experimenting with a magnetic disk device in which a servo head is disposed near the axial center of the carriage shaft 14 and data heads are provided elsewhere, it has become possible to significantly reduce thermal off-track and φ.

Moreover, this intermediate member 20, as shown in FIG.
It may be formed in multiple layers like the intermediate members 20a, 20b, etc.

In this case, the thermal expansion coefficient of the intermediate member 20a is set to 15XIO-
', while the thermal expansion coefficient of the intermediate member 20b is 20X1
It is best to set it to 0 first.

A member having such a coefficient of thermal expansion can be made to have a coefficient of thermal expansion of 14 to 23X1 by changing the content of SI, for example.
g in the range 0-'! A quenched aluminum powder alloy can be used.

In the above-mentioned embodiments, the housing to which the magnetic head arm is fixed is press-fitted or fired into the carriage shaft, but the present invention is not limited thereto. It is also possible to apply the present invention to a rotation mechanism for a magnetic disk disk using a spindle shaft that is press-fitted or fired into a spindle housing that holds the disk.

〔Effect of the invention〕

As explained above, according to the present invention, since a member whose thermal expansion coefficient is located between the housing and the shaft is interposed between the housing and the shaft, the temperature within the magnetic disk drive increases. It becomes possible to reduce the variation in the magnitude of thermal stress accompanying the rise along the axial direction of the shaft, and it becomes possible to reduce thermal off-track.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment, FIG. 2 is an explanatory diagram of another embodiment, and FIG. 3 is a diagram showing the configuration of a conventional magnetic disk device. In the figure, 13 is a housing, I4 is a carriage shaft, and 2o is an intermediate member. ~ to ＼←

Claims (1)

[Scope of Claims] A housing on which a magnetic disk disc or a magnetic head arm is mounted; a shaft on which the housing is press-fitted or shrink-fitted; A magnetic disk drive characterized in that a member is press-fitted or shrink-fitted between a coefficient of thermal expansion of the shaft and a coefficient of thermal expansion of the shaft.