JPH03216872A - Linear guide mechanism - Google Patents

Abstract

PURPOSE:To improve the positioning precision of a guide mechanism by providing a member which provide a force in the axial direction to the outer wheel of a guide bearing of a linear guide mechanism. CONSTITUTION:A guide bearing 9 whose outside periphery the guide mechanism is constituted on is attached to a carriage 5 guided by the linear guide mecha nism and is pressed to a guide path 16 and rolls on the guide path 16 in the direction perpendicular to the drawing by rotation of the outer wheel. A force in the radial direction is given to a prepressure bearing by a spring member and this bearing is pressed to the guide path 16. As a result, the attitude of the carriage 5 is determined. The member to give the force in the axial direction to an outer wheel 12 of the guide member 9 is provided to cancel the force of friction between the outer wheel 12 of the bearing and the guide path 16, thereby preventing movement in the axial direction of the outer wheel 12 of the bearing and the guide path 16, thereby preventing movement in the axial direction of the outer wheel. Thus, the positioning precision of the linear guide mechanism is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a linear guide mechanism with improved precision for accessing a head in a magnetic disk drive.

[Conventional technology]

In the conventional device, as described in LISP 4,743,987, a guide wheel is pressed against a rail to constitute a guide mechanism. There are no special improvements made to the guide wheel itself, and the effects of assembly errors are not taken into consideration. In the structure of this conventional device, if there is an assembly error in the guide wheel, that is, the guide bearing, the following problems occur.

One is that when the contact point between the guide bearing outer ring and the rail is slightly offset from the center of the guide bearing outer ring, the frictional force between the guide bearing outer ring and the rail causes the contact point between the outer ring and the rail to move in the normal direction to the rail surface. A moment acts on the outer ring to rotate it. This moment made the running of the outer ring unstable, causing a decrease in positioning accuracy.

Another case is when the guide bearing is assembled at an angle to the rolling direction. In this case, the outer ring of the guide bearing moves in the axial direction, and as a result, the distance between the rotating shaft of the guide bearing and the rail changes, causing a decrease in positioning accuracy. The axial movement of the outer ring causes the bearing to run unstable, and also causes the outer ring to warp between the outer ring and the rail, causing wear.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the influence of assembly errors of the guide bearing, and the rolling elements of the bearing ride on the raceway groove, causing a change in the distance between the inner ring shaft and the guideway, which can lead to a change in the positioning accuracy of the linear guide mechanism. This can cause problems such as deterioration of the bearing, and wear due to slipping between the outer ring of the guide bearing and the guideway.
There was an error that reduced the reliability of the linear guide mechanism.

An object of the present invention is to improve the positioning accuracy of a linear guide mechanism and to provide a magnetic disk device equipped with a highly reliable linear guide mechanism.

[Means to solve the problem]

In order to achieve the above objective, a member is provided on the outer ring or inner ring shaft of the bearing that applies a force that cancels out some or all of the frictional force between the guideway and the guide bearing, and This improves the guiding accuracy of the linear guide mechanism by preventing the movement of the rolling element and preventing the rolling body from riding on the raceway groove.

In addition, part of the frictional force between the guideway and the guide bearing, or
By using the repulsion or attraction of magnetic materials as a method of applying a force that cancels out all of the forces, it is possible to apply force to the bearing without contact, which not only absorbs assembly errors to some extent, but also reduces the running speed of the bearing. can be stabilized, so the guiding accuracy of the linear guide mechanism can be improved.

[Effect]

The linear guide mechanism of the present invention includes a member that applies an axial force to the outer ring of the guide bearing, cancels the frictional force between the outer ring of the bearing and the guide path, and prevents the outer ring from moving in the axial direction.

When the bearing moves in the axial direction, the rolling elements of the bearing ride on the raceway groove, resulting in a change in the distance between the inner ring shaft and the guideway. This change in distance causes the attitude of the movable body guided by the linear guide mechanism to change depending on the location of the guide mechanism, impairing reproducibility depending on the position. This causes a decrease in the positioning accuracy of the linear guide mechanism, but the present invention can prevent the outer ring of the bearing from moving in the axial direction, making it possible to maintain good positioning accuracy of the linear guide mechanism.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
The figure shows a longitudinal cross-sectional view of the linear guide mechanism. here,
A case where the linear guide mechanism is applied to a magnetic disk device will be explained.

The capacity of recent magnetic disk drives has been increasing year by year, and the biggest challenges are increasing density and throughput.

Among these, in order to achieve higher density, it is necessary to improve the guiding accuracy of the linear guide mechanism for accessing the head.

In the embodiment shown in FIG. 1, a guide bearing 9 constituting the guide mechanism is attached to the outer periphery of the carriage 5 guided by the linear guide mechanism, and the guide bearing 9 is attached to the guide path 16.
, and rolls on the guide path 16 in a direction perpendicular to the drawing by rotation of the outer axis.

The preload bearing 34 is applied with a radial force by the spring member 24 and is pressed against the guide path 16 . This pressing force is also applied to the other guide bearings 9, and as a result, the attitude of the carriage 5 is determined. The guide bearing 9 has
Furthermore, an axial force is applied by a preload member 35. This preload member 35 has one force generating member 25 embedded in the outer shaft 12 of the guide bearing, and the other force generating member 25 embedded in a lid 26 provided on the outside of the outer shaft 12 of the guide bearing. When the outer ring 12 approaches either force generating member 25, an axial force acts on the outer ring 12 and pushes it back in the opposite direction. In this case, a repulsive force is utilized in which an axial force is applied when the outer ring 12 approaches the force generating member 25. Magnetic materials, ie, permanent magnets, are well-known as materials that can utilize repulsive force. The preload member 35 applies an axial force to the outer ring 12 of the guide bearing, and as the outer ring 12 is always held at the center position of the bearing, the rolling of the outer ring 12 becomes stable, and moreover, the rolling body 13 of the bearing 9 The linear guide mechanism does not run on the raceway groove, and a highly accurate linear guide mechanism can be achieved.

The structure and operating principle of one embodiment of the present invention have been explained above.Next, we will show the overall structure of a magnetic disk drive in which a linear guide mechanism is used, and explain the role of the linear guide mechanism and the necessity of guiding accuracy. We will also explain the operation of guide bearings and their problems.

Figure 2 shows the overall structure of a magnetic disk drive, which includes a head 3 for reading and writing data, a disk 1 on which data is stored, a spindle motor 2 that rotates the disk 1, and a guide arm 4 that supports it. A carriage 5 on which the head 3 is mounted, a guide bearing 9 and a guide path 8 that guide the carriage 5, a base 11 that supports the guide path 8 and the spindle motor 2, and a voice coil 7 and a magnet that make the carriage 5 perform an access operation. 6 and voice coil 7
, a control circuit 38 that controls data reading/writing and the drive circuit 37, and a continuous member 10 that elastically connects the base 11 and the magnet 6.

The carriage 5 is driven by a voice coil motor composed of a voice coil 7 and a magnet 6, and reciprocates on a guide path 8. As a result, data written on the disk 1 is read and data is written on the disk 1. To read and write this data, the head 3 at the tip of the carriage 5 must be positioned at an arbitrary point on the disk 1. The accuracy of this positioning depends on the accuracy with which the carriage 5 is guided on the guide path 8 and the accuracy of the control circuit 38 using a position signal that the head 3 detects from above the disk. The assembly accuracy of the guide bearing 9 has a negative effect on this positioning accuracy. FIG. 3 is a sectional view of the guide bearing 9 when a part of the linear guide mechanism of FIG. 2 is viewed from the access direction of the carriage 5. Among the assembly accuracy of the guide bearing 9, the positioning accuracy is most affected when the guide bearing 9 is assembled at a certain angle to the access direction of the carriage 5 as shown in FIG. . Figure 4 shows
FIG. 4 is a partial plan view of the linear guide mechanism when the guide bearing 9 of FIG. 3 is viewed from above. The angle β in Fig. 4 is called the slip angle in vehicle relations, and if this angle is dependent, the fourth
In the figure, when the carriage 5 performs an access operation in the direction of arrow a, the guide bearing 9 is moved in the direction of arrow b. This is because a frictional force acts between the guide bearing's outer part 12 and the guideway 16, and this frictional force causes the outer ring 12 to move in the axial direction with respect to the inner ring shaft 14. Foreign export 1
The range in which the guide bearing 2 moves is within the range of the axial clearance of the guide bearing 9 at most.

FIG. 5 is a partial sectional view of the guide bearing when the outer ring 12 of the guide bearing is displaced in the axial direction. Due to this axial displacement of the outer ring, the rolling body 13 moves into the raceway groove 4 of the guide bearing 9.
As a result, the distance between the inner race shaft 14 and the guideway 16 changes.

This change in distance changes the attitude of the carriage 5, so
Decrease the guiding accuracy of the linear guide mechanism.

Changes in the posture of the carriage 5 affect the relative positions of the disk 1 and the head 3, and as a result, the positioning accuracy of the head 3 is adversely affected. In particular, one head detects the position signal written on disk 1,
In other magnetic disk drives that position a plurality of heads, this effect is significant and poses a serious problem of decreased positioning accuracy.

The change in the distance between the inner ring shaft 14 and the guideway 16 is
The amount of movement in the axial direction is expressed by the following equation.

O〈Δ＜c,/2 Δ: Amount of change in the distance between the inner ring shaft and the guideway (=amount of rolling body riding on the raceway groove) Radial clearance of the bearing Radial deviation of the inner ring raceway groove Radius of the outer ring raceway groove Contact angle between the body and the inner raceway Contact angle between the rolling body and the outer raceway Diameter of the rolling body Axial movement of external rotation Change in the distance between the inner race shaft and the guideway is It depends on the amount of movement. The amount of axial movement of the outer ring is determined by the balance between the frictional force between the outer ring and the guideway and the axial force generated by the rolling body running onto the raceway groove, or by the axial clearance of the bearing. The upper limit is determined by being constrained up to.

Therefore, in order to maintain high guiding accuracy of the linear guide mechanism, it is necessary to restrict the movement of the outer ring of the guide bearing, or to
The structure may be such that the distance between the inner ring shaft and the guideway does not change even if the outer ring moves. The former method of restraining the movement of the outer ring is to provide a mechanical means to restrain the movement of the outer ring in the axial direction, or to eliminate the frictional force between the outer ring and the guideway as described above, that is, to suppress the outer ring of the guide bearing. A possible method is to set the friction coefficient between the guideway and the guideway to zero or a value close to it.

However, if the coefficient of friction is reduced to zero, the movement of the guide bearing becomes extremely unstable, so the present invention describes a method of restraining the movement of the outer ring of the guide bearing using mechanical means.

FIG. 6 shows another embodiment of the invention. In this embodiment, a preload member 36 is provided on one side of the guide bearing 9 12, and FIG. 7 is an enlarged view of the preload member shown in FIG. 6. In this embodiment, a permanent magnet is used as the force generating member 25, and its repulsive force is utilized to apply an axial force to the outer ring 12 of the guide bearing. When the carriage 5 reciprocates, the guide bearing 12 assembled at a certain angle with respect to the direction of movement of the carriage reciprocates in the axial direction due to the frictional force between the outer ring and the guide path 16. Therefore, if the method of this embodiment is to apply an axial force from one direction, the required magnitude of the axial force is given by the following equation.

F7≧ F, +μFr FP: Force applied by the preload member F1: Axial force generated inside the bearing Fr: How the guide bearing is pressed in the radial direction μ: Coefficient of friction between the outer ring and guideway Axial direction generated inside the bearing The force Fq is the force generated when the shaft body rides on the raceway groove, and from FIG. 5, the force Fq per rolling body is given by the following formula.

F q = F rqtan a o α0: Contact angle between the outer ring and the rolling body Frq: Radial force per rolling body The force generating member 25 on the outer ring side of the bearing is embedded in the outer ring of the bearing. This minimizes the volume of the outer ring of the bearing,
This is also to reduce the moment of inertia around the inner race shaft 14. If the moment of inertia of the outer ring becomes large, there is a possibility that the bearing will slip in the direction of rotation, which may lead to the generation of wear particles and a decrease in guiding accuracy. Therefore, by adding the preload member, there is no increase in the moment of inertia of the outer ring, and the size can be reduced. Also, in this embodiment, the outer ring is always pressed in the axial direction,
Moreover, the rolling body remains riding on the raceway groove. Therefore, there is no upward or downward movement of the inner ring shaft, and high guiding accuracy can be expected.

When the guide bearing is mechanically fixed in the axial direction, if the bearing is slightly tilted with respect to the guideway due to the assembly precision of the bearing, it may not be possible to absorb this, and the inside of the bearing, the outer ring and the guide There is a possibility of uneven collision between roads. This may also cause damage to the reliability of the guide machine. However, in the case of this embodiment, since force can be applied without contact, high guiding accuracy can be maintained without impairing the reliability of the guide mechanism.

In the embodiment shown in FIG. 7, repulsive force is used, but attractive force may also be used.

FIG. 8 is a cross-sectional view of a guide bearing according to another embodiment of the present invention. In this embodiment, a spring member 39 is used as the force generating member.
The spring member 39 is supported by a preload bearing 42 and is rotatable, and the preload bearing 42 and the guide bearing are coaxial.

This embodiment has the advantage that it is possible to have a large clearance between the preload bearing 42 and the outer shaft 12 of the guide bearing, easy to assemble, and easy to manage and set the magnitude of the axial force. .

No. 9 is a sectional view of a guide bearing according to another embodiment of the present invention. In this embodiment, the repulsive force of the force generating member 25 is used to apply axial self-force to the outer ring 12 of the guide bearing, and the force generating member 25 is movable in the axial direction, and the force generating member 25 was supported, and the spring member 30 was further supported by a spring member presser 29. As a result, the force generating section 25
By maintaining an appropriate distance between the outer ring and the guide bearing 12 and inserting the spring member 30, the pre-rotting member can be easily assembled and the outer ring can run stably.

FIG. 10 is a sectional view of a guide bearing according to another embodiment of the present invention. A preload member is provided between the guide bearing and the carriage 5, and the attraction force of the permanent magnet 17 is used to apply an axial force to the outer ring.

A magnetic fluid 18 is inserted between the permanent magnet 17 and the guide bearing 12 to apply force and to seal the bearing with grease. An oil seal 15 is provided on the other outer ring of the bearing, so that the bearing is completely sealed, and there is no fear of grease scattering inside the bearing.

FIG. 11 is a sectional view of a guide bearing according to another embodiment of the present invention. The force generating member 21 is embedded in an oil seal plate 20 attached to the outer ring 12 of the bearing, and the force generating member 22 is embedded in the inner ring shaft 14 of the bearing to form a preload member. The force generating member may utilize repulsion or suction.

This configuration has the advantage of being the most compact.

Also, assembly is easy.

FIG. 12 is an explanatory diagram of another embodiment of the present invention.

If excessive axial force is applied to the guide bearing 12,
If a bearing assembly error causes uneven contact between the outer ring of the bearing and the guideway, this bearing assembly error cannot be absorbed, and wear may occur due to the uneven contact between the outer ring and the guideway. This may cause a decrease in guidance accuracy and reliability. Therefore, as shown in Figure 13, when looking at the moment around the contact point between the outer ring and the guideway, the axial force should be set so that the moment due to the axial force is always smaller than the moment due to the pressing load of the bearing. This makes it possible to prevent the outer ring of the guide bearing from hitting one side.

DB 22 FP=Axial force D=Outer ring diameter F, : Bearing pressing load B : Outer ring width FIG. 14 is a longitudinal sectional view of a linear guide mechanism according to another embodiment of the present invention. This embodiment is a linear guide mechanism in which a guide bearing is provided in the housing 23 and a guide path is provided in the carriage 5. In this example, since the weight of the carriage 5, which is a movable part, can be reduced, there is an advantage that the speed can be increased. The preload member has a structure that pushes the outer ring in one direction with a repulsive force or pulls it with a suction force.

FIG. 15 is a partial sectional view of a linear guide mechanism according to another embodiment of the present invention. A preload member is provided between the guide bearing and the carriage, and the axial force of the preload member is generated using the suction or repulsion force of the force generating member 25. A member with a circular cross section is used for the guide path 32, and the guide path 32 is fixed to the housing 11 with a guideway fixing bolt 33. The inner ring shaft 14 of the guide bearing is fixed to the carriage 5 by press fitting, fixing with screws, fixing with adhesive, shrink fitting, or cold fitting.

When the guide path 32 has a circular cross section, the outer ring of the guide bearing and the guide path are in point contact. Therefore, if the contact point between the outer ring and the guide path is shifted from the center of the bearing due to an assembly error, a moment will act to rotate the outer ring. this is,
This makes the rolling of the guide bearing unstable, leading to a decrease in guiding accuracy and causing wear at the contact point between the outer ring and the guideway.

However, the rolling of the outer ring can be stabilized by applying an axial force to the outer ring using the preload member of the present invention and applying a moment to the outer ring that resists the moment acting from the guideway. The reason for this is that when the repulsive force of a permanent magnet is used for the force generating members 25, the repulsive force acts in inverse proportion to the distance between the force generating members 25. That is, the repulsive force is large on the side closer to the object, and smaller on the side farther away, and acts as a so-called restoring moment.

Therefore, the rolling of the outer ring of the guide bearing can be stabilized.
High guidance accuracy can be achieved.

FIG. 16 is an exploded view of a guide bearing according to an embodiment of the present invention. A lid 26 with one force generating member 25 fixed to the inner ring shaft 14 of the guide bearing is fixed with a bolt 43, and the lid 26 with the other force generating member 25 is connected to the inner ring shaft and the carriage through the inner ring shaft 14. fixed between the housing and the housing. As described above, a guide bearing according to an embodiment of the present invention is configured.

FIG. 17 shows a force generating member according to another embodiment of the present invention, in which the lid 26
This is a case where the force generating members 41 are distributed and provided on the outer circumference of the cylinder. This is effective in reducing weight, which is necessary to increase the speed of the linear guide mechanism.

FIG. 18 is a sectional view of a guide bearing according to another embodiment of the present invention. As for guide bearings, axial movement of the outer ring can occur not only in ball bearings but also in roller bearings. For roller bearings,
When the outer ring moves in the axial direction, the end surfaces of the rollers may come into contact with the cage, leading to wear and damage. According to this embodiment, the rolling stability and reliability of the guide bearing can be improved by applying force from both directions in the axial direction and by applying force in inverse proportion to the distance between the force generating member 25 and the outer ring. I can do it.

FIG. 19 is a cross-sectional view of a guide bearing according to another embodiment of the present invention. When a sliding bearing is used as a guide bearing, a situation similar to that shown in FIG. 18 may occur, and the present invention This effect can improve the stability and reliability of the guide bearing.

FIG. 20 is a longitudinal cross-sectional view of a guide bearing according to another embodiment of the present invention, in which static pressure (positive or negative pressure) of a fluid is used as a force generating means for a bridle member. This is effective in reducing weight because fewer members are required to be included in the guide bearing as a preload member.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

By providing the outer ring of the guide bearing of the linear guide mechanism with a member that applies an axial force, it is possible to offset the frictional force between the outer ring of the bearing and the guideway, and to stabilize the running of the bearing. Furthermore, the axial movement of the bearing shaft is prevented, and the rolling elements within the bearing are prevented from moving up and down in the raceway groove, thereby improving the positioning accuracy of the guide mechanism.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a linear guide mechanism according to an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of a magnetic disk drive, Fig. 3 is a longitudinal cross-sectional view of a guide bearing, and Fig. 4 is a cross-sectional view of a guide bearing. side view,
FIG. 5 is a partial vertical cross-sectional view of the guide bearing, FIG. 6 is a vertical cross-sectional view of a linear guide mechanism according to another embodiment of the present invention, FIG. 7 is a partial enlarged view of FIG. 6, and FIG. FIG. 9 is a vertical cross-sectional view of a guide bearing according to another embodiment of the present invention; FIG. 10 is a vertical cross-sectional view of a guide bearing according to another embodiment of the present invention; Fig. 11 is a longitudinal sectional view of a guide bearing according to another embodiment of the present invention, Fig. 12 is a longitudinal sectional view of the guide bearing, Fig. 13 is an explanatory diagram showing the area in which the axial force of the bearing is used, and Fig. 14. 15 is a vertical cross-sectional view of a linear guide mechanism according to another embodiment of the present invention, FIG. 16 is a vertical cross-sectional view of a linear guide mechanism according to another embodiment of the present invention, and FIG. 16 is a preload diagram of a linear guide mechanism according to another embodiment of the present invention. 17 is a perspective view of a preload member according to another embodiment of the present invention, FIG. 18 is a vertical sectional view of a guide bearing according to another embodiment of the present invention, and FIG. 19 is a diagram showing a preload member according to another embodiment of the present invention. FIG. 20 is a longitudinal sectional view of another guide bearing according to the present invention. 1...Disc, 2...Spindle motor, 3...
・Head, 4... Guide arm, 5... Carriage, 6... Magnet, 7... Voice coil, 8...
・Guideway, 9... Guide bearing, 1o... Connecting member,
11... Base, 12... Outer ring, 13... Rolling element, 14... Inner ring shaft, 15, 19... Oil seal,
16... Guide path, 17... Permanent magnet, 18... Magnetic fluid, 20... Oil seal plate. 21...
Force generating member, 22... Force generating member, 23... Bearing housing, 24... Preload member, 25... Force generating member,
26... Lid, 27... Preload member presser, 2nd close Fig. 3 l2 Fig. 4 l6 Fig. 5 '86 Fig. l0 Fig. l2 Fig. l3 Fig. Fine applied force F2'! , /4 Figure l6 Figure! 7 Figure 16 Figure 19 Figure 20 Figure 5 47

Claims (1)

[Claims] 1. A bearing in which a plurality of inner rings are fixed and an outer ring is freely rotatable;
A linear guide mechanism including a guide path with which the outer ring of the bearing rolls into contact, and a member that applies a force in a radial direction to maintain contact between the guide path and the bearing, the outer ring of the bearing being applied in an axial direction. A linear guide mechanism characterized by comprising a preload member that applies a force of.