JPH0430666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a spindle unit used in a device for reading information from a disk-shaped record carrier on which information is recorded according to a concentric or spiral track pattern. It is something.

2. Description of the Related Art Conventionally, spindle units used in reading devices for disk-shaped record carriers have structures shown in FIGS. 3 and 4.

The spindle unit in Figure 3 has bracket 1.
A rotary shaft 5 is rotatably supported by ball bearings 3 and 4 fitted on both ends of the inner circumference of the housing 2, and the two ball bearings 3 and 4 are mounted on the rotary shaft 5 in the axial direction. A spring 6 is provided between the inner peripheral shoulder of the housing 2 of the bracket 1 and the bearing 4 to apply a certain preload to the bearings 3 and 4. The structure is fixed to the bearing fitting surfaces of the bracket 1 and rotating shaft 5 in a state where the bearings 3 and 4 are provided with a preload, and by applying preload with the spring 6, the occurrence of rattling due to the existence of internal gaps between the bearings 3 and 4 can be prevented. This improves the rotational accuracy of the spindle. A is a disk-shaped record carrier mounting part, and B is a motor rotor holder, which are fitted and fixed to the rotating shaft 5, respectively.

By the way, the spindle unit for a reading device for a disk-shaped record carrier is small, and moreover,
Highly accurate rotational performance is required, and in particular, the radial runout R of the end of the rotating shaft on the disk-shaped record carrier mounting side is required to be 5 to 6 μm or less. In recent years, the storage capacity of devices has been required to be more and more accurate, and as a result, the runout accuracy has been reduced to 2.
It has become necessary to be able to stably obtain particles with a diameter of ~3 μm or less. However, as shown in FIG. 3, since the pair of bearings 3 and 4 that support the rotating shaft 5 are composed of outer rings 3a and 4a, inner rings 3b and 4b, and balls 3c and 4c, This causes variations in the accuracy of the fitting surface. Therefore, it is difficult to improve the radial runout accuracy of the rotating shaft 5 as described above. To solve this,
As shown in Fig. 4, a pair of bearings 7 and 8 are connected to outer rings 7a and 8.
a, inner ball raceway surface 7 formed directly on the rotating shaft 9
Consisting of b, 8b and balls 7c, 8c,
A small-diameter bearing seat is formed on the disk-shaped record carrier side and a large-diameter bearing seat is formed on the rotor holder side with an axial interval on the inner circumferential surface of the housing, and the outer ring 7a of the bearing 7 is fitted with a clearance into the small-diameter bearing seat. A structure has been proposed in which the outer ring 8a of the bearing 8 is tightly fitted (or intermediately fitted) into the bearing seat and a preload is applied to the pair of bearings 7 and 8 without using the spring 6 as shown in Fig. 3. .
A is a disk-shaped record carrier mounting portion, and B is a motor rotor holder, which are fitted and fixed to the rotating shaft 9, respectively.

Problems to be Solved by the Invention In the conventional structure as shown in Fig. 4, the ball raceway surface is formed directly on the rotating shaft compared to the structure shown in Fig. 3, so accuracy is easier to achieve. There is a problem.

(a) The axial spacing between both bearings 7 and 8 is narrow, making it difficult to assemble the bearings and increasing the bearing manufacturing cost.

(b) In the structure in which a preload is applied to a pair of bearings 7 and 8 by press-fitting the outer ring 8a of one bearing 8 into the housing 2 as described above, the force application point P of both bearings 7 and 8 is
1 and P2 are respectively located on the other bearing side, that is, between the two bearings, the axial distance L between the force application points P1 and P2 becomes short, which is disadvantageous for reducing the radial runout R of the rotating shaft 9. In this specification, the force application point refers to the point where the line of action that forms the contact angle of the bearing intersects the center line of the bearing.

(c) A large thrust load acts on the bearing 7 or the bearing 8 due to the magnetic attraction force of the device, but since the outer diameter dimensions of the rotating shaft 9 are determined, the ball and raceway diameters become small, and the rated bearing It is difficult to design a large load and the bearing life will be shortened.

(d) Run-out of the rotating shaft 9 on the bearing 7 side in particular is a problem, but the outer ring of the bearing 7 and the housing must be fitted with a loose fit, making it difficult to achieve run-out accuracy of the rotating shaft 9.

Means for Solving the Problems The present invention solves the above problems by forming a small diameter bearing seat on the disk-shaped record carrier side and a large diameter bearing seat on the rotor holder side at an axial distance on the inner circumference of the housing. A rolling bearing is placed in each bearing seat,
In the above-mentioned pair of rolling bearings, a rotary shaft is rotatably supported, with the mounting part of the disc-shaped record carrier at one end and the rotor holder of the motor at the other end, in which the mounting part side of the disc-shaped record carrier The rolling bearing located on the rotor holder side is composed of a ball bearing having an outer ring fitted in a housing, balls, and a ball raceway surface formed on the shaft, and the rolling bearing located on the rotor holder side has a higher rated load than the bearing. The ball bearing is a large bearing and has an outer ring fitted to a housing, balls, and an inner ring fitted to a shaft. This problem is solved by a spindle unit for a reading device for a disc-shaped record carrier, which is characterized in that a preload is applied depending on the amount of axial pushing against the disc.

Effects According to the configuration of the present invention, a rolling bearing located on the mounting portion side of a disk-shaped record carrier that requires rotational accuracy is connected to an outer ring fitted in a housing, a ball, and a ball track formed on the shaft. A pair of bearings that rotatably support the rotating shaft are composed of ball bearings having a surface, and the inner ring of the bearing is located on the side opposite to the mounting part side of the disk-shaped record carrier (on the rotor holder side of the motor). Since preload is applied by pushing the rotating shaft in the axial direction, the point of application of force on each bearing is not on the other bearing side, that is, between the two bearings.
Since it is located on the opposite side to the other bearings, that is, on the outside of both bearings, the axial distance between the force application points becomes longer, and the radial deflection of the tip of the rotating shaft on the disk-shaped record carrier mounting side becomes smaller. Furthermore, since the thrust load that acts on the rotating shaft during operation of the apparatus generally acts from the rotor holder side to the record carrier mounting side, it is received by a bearing with a large rated load located on the rotor holder side of the motor.

Examples Examples according to the present invention will be described. In FIG. 1, reference numeral 10 denotes a rotating shaft having a disk-shaped record carrier mounting portion 11 at one end and a rotor holder 12 of a motor (not shown) at the other end. The rotating shaft 10 is connected to the housing 1 of the bracket 13.
Bearing seats 15 and 16 are formed at a certain axial distance on the inner circumference of bearing seat 1.
6 is formed to have a large diameter, and is rotatably supported by a pair of ball bearings 17 and 18 arranged in bearing seats 15 and 16. The bearing seat 15 located on the disk-shaped record carrier mounting part 11 side is the other bearing seat 16.
The bearing seat 1 is formed with an inner diameter d smaller than
The ball bearing 17 arranged at 5 includes an outer ring 17a fitted to the housing 14, balls 17b, a ball retainer 17c, and a ball raceway surface 1 formed directly on the shaft 10.
7d. Rotor holder 12
The bearing seat 16 located on the side is formed with an inner diameter D larger than that of the bearing seat 15, and the ball bearing 18 disposed in the bearing seat 16 has an outer ring 18a fitted in the housing 14, balls 18b, and balls. a retainer 18c,
The inner ring 18d is press-fitted onto the shaft 10. The bearing 17 is arranged in a tight fit with respect to the housing 14. The inner ring 18c of the bearing 18 is press-fitted into the rotating shaft 10 in the axial direction. This applies preload to both bearings.

That is, after assembling the rotating shaft 10, housing 14, and bearing 17 as shown in FIG. 2, the bearing 18 is pushed in the direction of arrow N between the rotating shaft 10 and the housing 14, and is press-fitted. In this case, the inner ring 18d of the bearing 18 is pushed in the axial direction with the rotating shaft 10 in an interference fit or an intermediate fit, and when the side surface of the outer ring 18a contacts the inner diameter shoulder 19 of the housing 14, the pushing force is released. Ball 18b, outer ring 1
8a, housing 14, outer ring 17a, ball 17b,
It is transmitted in the order of the ball raceway surface 17d of the shaft 10, and the inner ring 1
8d is positioned in the axial direction with respect to the rotating shaft 10,
A preload is applied to both bearings 17 and 18 depending on the pushed-in position, and the preload is adjusted. Also,
Respective force application points P3 and P4 of both bearings 17 and 18
is on the other bearing side, that is, not between the two bearings 17 and 18, but on the opposite side to the other bearings, that is, both the bearings 17 and 1.
8, and the axial distance L1 between the force application points P3 and P4 is longer. On the other hand, since the thrust load acting on the spindle unit acts from the rotor holder 12 side toward the disk-shaped record carrier mounting section 11 side, the thrust load acts only on the rotor holder 1.
It acts on the ball bearing 18 located on the second side. Since the ball bearing 18 has a larger internal structure than the ball bearing 17 located on the side of the disk-shaped record carrier mounting section 11, it has a large rated load and can therefore sufficiently receive the thrust load. .

Effects of the Invention According to the configuration of the present invention, the bearing located on the mounting portion side of the disk-shaped record carrier is a ball bearing having an outer ring fitted in the housing, balls, and a ball raceway surface formed on the shaft. Moreover, since the inner ring of the other bearing (located on the rotor holder side) is pressed into the rotating shaft, a preload is applied to both bearings, which eliminates the variation in accuracy of the fitting surface as in the conventional case. Since the influence on the radial runout of the rotating shaft due to this is reduced and the distance between the points of application of force is increased, rotation accuracy can be significantly improved. Further, since the thrust load acting on the spindle unit is borne by a ball bearing located on the rotor holder side and having an outer ring, an inner ring, and balls and having a large rated load, the life of the spindle unit can be improved. Furthermore, bearing assembly work involves assembling the outer ring, balls, and
Since the cage can be assembled in a single line, it can be easily installed without any difficulty in the same way as with ordinary ball bearings.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is an explanatory view showing the assembly procedure, and FIGS. 3 and 4 are sectional views of a conventional example. DESCRIPTION OF SYMBOLS 10... Rotating shaft, 11... Mounting part for disk-shaped record carrier, 12... Motor rotor holder, 13... Bracket, 14... Housing,
17, 18...ball bearing, 17a, 18a...outer ring, 17b, 18b...ball, 17d...ball raceway surface, 18d...inner ring.

Claims (1)

[Claims] 1 A small-diameter bearing seat is formed on the disk-shaped record carrier side and a large-diameter bearing seat is formed on the rotor holder side at an axial distance on the inner circumference of the housing, and a rolling bearing is arranged on each bearing seat, and the pair of rolling bearings ,
In a device having a mounting portion for a disk-shaped record carrier at one end and rotatably supporting a rotating shaft having the rotor holder of a motor provided at the other end, a rolling bearing located on the side of the mounting portion for the disk-shaped record carrier, It is composed of a ball bearing having an outer ring fitted in a housing, balls, and a ball raceway surface formed on the shaft, and the rolling bearing located on the rotor holder side is a bearing with a higher load rating than the bearing, and the housing The ball bearing has an outer ring fitted to the rotor holder, a ball, and an inner ring fitted to the shaft. A spindle unit for a reading device for a disk-shaped record carrier, characterized in that a preload is applied.