JPS62298102A - Manufacture of magnetic fluid sealing device - Google Patents

Abstract

PURPOSE:To obtain a perfect magnetic fluid sealing film by a method wherein, using a special jig, a shaft is inserted while the pole piece located on the opposite side of the shaft inserting side is being short-circuited magnetically. CONSTITUTION:A pole piece 3, on the opposite side of the inserting side of a shaft 5, and the shaft 5 are magnetically short-circuited using the jig consisting of a soft magnetic sleeve 7 and a soft magnetic ring 6. Under the condition wherein the short-circuited state is being maintained, the shaft 5 is inserted into annular pole pieces 2 and 3 and an annular permanent magnet 1, and the jig is removed after the inserting work is finished. As a result, the magnetic fluid 4 is caught on the inner circumferential side of the magnet 1 and it forms a perfect sealing film not only between the pole piece 3 and the shaft 5 but also between the pole piece, 2 and the shaft 5. Consequently, a perfect sealing film can be formed between the pole pieces 2 and 3 and the shaft respectively, and the reliability of the title sealing device can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic fluid sealing device to which this method is preferably applied.

Various improvements have been made to hard disks as magnetic recording media to improve their reliability. For example, the cleanliness of the space inside the disc pack containing the disc is particularly important.

In order to maintain this cleanliness, a magnetic fluid seal is attached to the spindle portion of the disk, and improvements have been made to prevent grease mist from the spindle bearings or dust from outside the disk pack from entering the disk pack. There is.

However, the conventional magnetic fluid seal device has a drawback in that the magnetic fluid ring membrane is often broken as a result of unstable pressure resistance as a seal.

This is a serious problem for magnetic fluid seals that require high reliability.

In other words, the typical structure of the magnetic fluid seal device is, as shown in FIG. A ferromagnetic shaft 5 passing through the inner diameter side of the parts 1, 2.3 in a similar manner, the shaft 5 and the ball piece 2,
Two magnetic fluid ring membranes (4) magnetically captured in the space between the two magnetic fluid shaft devices (3) constitute a magnetic fluid shaft device.

The procedure for assembling this device is as shown in FIG.
is inserted.

However, ideally, the magnetic fluid ring 4 should form a complete ring around each ball piece as shown in FIG. As shown in the figure, the magnetic fluid film on one side of the ball piece 2 often becomes incomplete.

This incomplete magnetic fluid ring on the ball piece 2 side is often broken when the pressure on the PA side decreases or when the seal internal pressure Pi increases due to temperature rise, etc., as shown in FIG. Inconveniences such as scattering outside the fluid seal device will occur.

In view of this, the main object of the present invention is to propose a method for using this type of device using a special jig in order to maintain a complete sealing structure for magnetic fluid when assembling the sealing device.

An embodiment of the present invention will be described in detail below with reference to the drawings.

5 to 8 are diagrams showing examples of each step of the method of the present invention.

First, in FIG. It is connected to the ball piece 3 by a soft magnetic sleeve 7 and a soft magnetic ring 6.

Therefore, as shown in FIG. 6, the magnetic field in the gap between the ball piece 2 and the shaft 5 is strengthened, and the magnetic fluid 4 comes to flow into this gap. Therefore, the shaft 5 is moved to the installation position with respect to the magnet 1, the ball piece 2.3, and the magnetic fluid 4.

For this reason, the magnetic fluid 4 has a strong magnetic field in the gap between the ball piece 2 and the shaft 5, so it becomes as shown in FIG.
By removing the ring 6 and sleeve 7, two ideal magnetic fluid rings are created as shown in FIG.

As an example of the pond for jig 6 and 7, as shown in Figure 9,
The ring 6 can be divided into a portion 62 that contacts the sleeve 7 and a portion 61 that contacts the ball piece 3.

As described above, according to the present invention, the magnetic fluid is captured in the opening between the axially magnetized annular magnet, the inner diameter side of the annular ball piece concentrically joined to both ends, and the shaft concentrically penetrated. In the assembly method, the magnetic fluid is once magnetically captured on the inner diameter side of the magnet, and then the shaft is inserted while magnetically short-circuiting the shaft and the ball piece on the opposite side to the insertion side of the shaft. Since the short circuit is removed and the other seal is installed, the magnetic fluid seal film is sound and the magnetic fluid does not scatter due to deterioration of seal pressure resistance, making it highly reliable. It becomes possible to provide a magnetic fluid seal device.

[Brief explanation of the drawing]

1, 2, 3, and 4 are sectional views for explaining the conventional method, and FIGS. 5, 6, 7, and 8 show an embodiment of the present invention. Each process diagram and FIG. 9 are cross-sectional views showing examples of jig ponds. 1... Magnet, 2, 3... Ball, piece, 4...
Magnetic fluid, 5... shaft, 6, 7... jig.

Claims (1)

[Claims] A method of assembling an annular magnet magnetized in the axial direction, an annular ball piece concentrically joined to both ends, and a magnetic fluid captured between the inner diameter side of the annular ball piece and a shaft concentrically penetrated. After the magnetic fluid is once magnetically captured on the inner diameter side of the magnet, the shaft is inserted while magnetically short-circuiting the shaft and the ball piece on the opposite side to the insertion side of the shaft to seal one side. A method for manufacturing a magnetic fluid seal device, characterized in that the short circuit is removed and the other seal is provided.