JPH0364948B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a mechanism for linearly guiding a traveling platform along a guide rail, in a device for linearly transporting a traveling platform over a certain range, that is, a guiding mechanism for the traveling platform.

[Prior art and its problems]

Generally, in a mechanism for linearly guiding a carriage along a guide rail, play of the carriage in directions other than the guiding direction, that is, the feeding direction, is usually extremely strictly suppressed. Additionally, it is required to reduce the load as much as possible during sending. Particularly when used in a magnetic disk device, the play in directions other than the feeding direction required for the guide mechanism of the traveling platform equipped with the magnetic head, the load required for feeding, or the mass of the traveling platform including the magnetic head are extremely severe. subject to restrictions. A conventional example of a guide mechanism used in a magnetic disk device will be described with reference to FIG. 6A shows a plan view of a conventional example, FIG. 6B shows a front view thereof, and FIG. 6C shows a side view thereof. 1 is a step motor, and 2 is a capstan, which is attached to the shaft of the step motor 1. A steel belt 3 is wrapped once around the capstan 2 and fastened at one point with a pin or screw to prevent it from slipping. On the other hand, the traveling platform 4 equipped with a magnetic head (not shown) has two guide rails 10A and 10 arranged in parallel, each having a circular cross section, as will be described later.
It is guided along the axial direction of B. The feed of the traveling base 4 is carried out by the steel belt attachment part 4 of the traveling base 4.
Both ends of the steel belt 3 are fixed to A and 4B, and the step motor 1 is rotated.
A shaft 14 is press-fitted and fixed at positions A1, A2, and B corresponding to each vertex of a triangle arranged on one side of the traveling base 4, and a radial ball bearing 6 (not shown) is attached to the other end of the shaft 14. The inner ring is press-fitted, and the V-grooved wheel 7 is press-fitted into the outer ring of this radial ball bearing 6. said position
The direction in which A1 and A2 are connected is the steel belt 3.
Both ends of the step motor 1 are set parallel to the direction of movement by the rotation of the step motor 1. Said V-groove wheel 7
The guide rails 10A, 10B are in contact with the groove surfaces of the guide rails 10A, 10B.
is placed. At this time, the guide rail 10
One guide rail 10A of A, 10B is fixedly held at both ends, but the other guide rail 10B
A preload is applied by means of a spring 8, shown schematically, towards the guide rail 10A and at right angles to the axial direction of the guide rail 10A.
The preload has the function of removing play in the radial direction between the inner and outer rings of the radial ball bearing 6 press-fitted into the center of the V-grooved wheel 7. Further, a radial ball bearing 13 is provided on the traveling platform 4 using a mounting bracket 11 and a shaft 12. That is, the mounting bracket 11 is
It is bent at a substantially right angle, and is fixed to the surface of the traveling table 4 by screwing on one side, and a shaft 12 is fixed to the end of the other side perpendicular to this plane,
The radial ball bearing 13 is press-fitted into the end of this shaft 12. Furthermore, the mounting bracket 11 has spring properties in the radial direction of the radial ball bearing 13. The radial ball bearing 13 is arranged to support the guide rail 10A from below, and due to the spring action of the mounting bracket 11 mentioned above, the guide rail 10A
gives an upward force to Therefore, a reaction force of the above-mentioned upward force acts on the radial ball bearing 13, and the play in the radial direction of the radial ball bearing 13 is removed by this reaction force. Further, due to the upward force acting on the guide rail 10A from the radial ball bearing 13, the guide rails 10A, 1
0B applies a force with a component in the vertical direction to the V-grooved wheel 7 at its point of contact. With this power,
Of the play between the inner and outer rings of the radial ball bearing 6, the play in the thrust direction is removed. As described above, in the conventional guide structure for the traveling platform 4, the radial ball bearing 13 is installed in order to eliminate the play in the thrust direction between the inner and outer rings of the radial ball bearing 6, which is the rolling part. make use of,
It is necessary to apply a certain force with a component force in the thrust direction. This not only increases purchasing costs due to additional parts but also increases man-hours for assembly and adjustment. Furthermore, especially in the case of a magnetic disk device, there is a drawback that the increased mass of the running platform impedes the basic function of the magnetic disk device, which is high-speed access.

[Purpose of the invention]

The purpose of this invention is to eliminate the above-mentioned drawbacks of the conventional example, to make the guide system of the traveling platform free from play through a simpler structure, and at the same time to reduce the weight of the traveling platform. be.

[Key points of the invention]

The main points of the present invention to achieve the above object are as follows. Three wheels with a radial ball bearing inserted in the center and a V-groove on the outer periphery are arranged with their centers aligned with each vertex of a triangle, and all wheel surfaces aligned with the surfaces of the triangle. do. Commonly contacts the V grooves of two of these three wheels,
A cylindrical first guide rail is installed. Then, the third wheel is translated in its axial direction, that is, by a certain distance in a direction perpendicular to the triangular surface. A cylindrical second guide rail is installed in contact with the V-groove of the third wheel and parallel to the first guide rail.
Axles are fitted into the inner rings of radial ball bearings fitted into the centers of the three wheels described above, and the ends of the axles are fixed to the traveling platform. Now, the first guide rail is fixed at both ends, and the second guide rail is supported at both ends so as to be movable parallel to the first guide rail and also parallel to the initially assumed triangular plane. ing. A force (hereinafter referred to as a preload) is constantly applied to both ends of the second guide rail in the direction in which it approaches the first guide rail in the above-mentioned movable direction. The carriage is therefore balanced by the forces from the first and second guide rails acting on the V-grooves of the three wheels attached to the carriage. From this, if the gravity acting on the traveling platform is ignored, the forces acting on the traveling platform from the first and second guide rails will be opposite to each other in the direction connecting the centers of the first and second guide rails. It is thought that the force is the same size. Due to this force, the radial ball bearing fitted into the center of the wheel receives a moment, and the play existing between the inner ring and the outer ring is removed. The relationship of the above-mentioned acting forces will be specifically described in the description of the embodiment in the next section.

[Embodiments of the invention]

One embodiment of the present invention will be described with reference to FIGS. 1 to 3. In FIG. 1, a represents a plan view of this embodiment.
b shows its side view. Reference numeral 4 denotes a running platform, on which a magnetic head is mounted in the case of a magnetic disk device. An axle 5 is fixed to positions A1, A2, and B on the traveling base 4, and an inner ring of a radial ball bearing 6 is fitted into the other end of the axle 5, and an outer ring of the radial ball bearing 6 is attached to the other end of the axle 5. A wheel 7 having a V-groove on its outer periphery is fitted. Note that all the axles 5, radial ball bearings 6, and axles 7 are the same, the directions of the axles 5 are all the same, and the wheels 7 attached to positions A1 and A2 are on the same plane. Further, in FIG. 1a, it is assumed that A1.B=A2.B. A guide rail, which will be described later, is installed in contact with this V-groove. That is, the first guide rail 10A is inserted into the V groove of the two wheels 7 fixed at positions A1 and A2.
0B is parallel to the first guide rail and at position B
The wheels 7 are in contact with the V grooves of the wheels 7 fixed to the wheels 7, respectively. The first guide rail is fixed at both ends thereof. The second guide rail is supported at both ends so as to be movable parallel to the surface of the wheel 7 in contact with the second guide rail and also parallel to the first guide rail. A certain force, called a preload, is constantly applied to both ends of this second guide rail by a spring 8. The main configuration of this embodiment is as described above, but next we will explain how force acts on each component and
How this force works will be explained in detail with reference to FIG. Fig. 2a shows the external force acting on the first guide rail 10A and the second guide rail 10B as shown in Fig. 2b.
is for the system formed by the traveling platform 4, axle 5, radial ball bearing 6, and wheels 7, and from the wheels 7 in contact with the first guide rail 10A and the wheels 7 in contact with the second guide rail 10B. This is to explain each external force that acts. FIG. 2a corresponds to a side view of the embodiment described above. First, consider the external force acting on the second guide rail 10B. As described above, the force by the spring 8, that is, the preload P is applied to this second guide rail in the horizontal direction. Note that since the force by the spring 8 is acting on both ends of the second guide rail 10B, the preload P indicates the resultant force. Since it is supported at both ends of the second guide rail 10B so as not to move in the vertical direction, the force from this support surface is assumed to be N. It is assumed that the support surface is a smooth surface, and the weight of the second guide rail 10B can be ignored. Further, a force Q from the wheels 7B that is in contact with the second guide rail 10B is acting on the second guide rail 10B. The line of action of this Q is a line connecting the center Oa of the first guide rail 10A and the center Ob of the second guide rail 10B, as will be described later.
Therefore, Q and N can be determined on the condition that the above three forces P, N, and Q are balanced. Note that θ is the angle that Oa and Ob make with the horizontal direction. For the horizontal direction, Q cosθ=P For the vertical direction, Q sinθ=N Therefore, Q=P/cosθ, N=P tanθ Next, let us consider the external force acting on the first guide rail 10A. That is, if the horizontal and vertical component forces of the resultant force of the forces that the first guide rail 10A receives from the supporting parts at both ends are Pa and Na, respectively, then the effect of these forces is calculated from the condition that the system of the traveling platform 4 is in equilibrium. The line is the first
The plane that vertically bisects line segments A1 and A2 in the figure is the first
It passes through Oa, the point that cuts the center axis of the guide rail 10A.
In other words, it coincides with the line of action of P. In addition, the first guide rail 10A is located at positions A1 and A2 of the two wheels 7.
If the resultant force received from A is Qa, this Qa also passes through Oa above. Therefore, in the horizontal direction, Qa cosθ=Pa In the vertical direction, Qa sinθ=Na On the other hand, the traveling platform 4, the axle 5, the radial ball bearing 6,
The external force acting on the system consisting of the axle 7 is the resultant force of the force acting on the wheel 7A from the first guide rail 10A, Qa, and the second guide rail 10B, as shown in FIG. 2b.
There are two forces, Q and Q acting on the wheel 7B.
Here, since the system of the traveling platform 4 is in equilibrium, Qa and Q are equal in size and in the direction.
It must coincide with a line connecting the center Oa of the first guide rail 10A and the center Ob of the second guide rail 10B. This is because otherwise, the system of the traveling platform 4 cannot be in equilibrium. That is, Qa=Q
It is. Similarly, based on Figure 2a, Pa=
P, Na=N. The force Qa=Q in the above explanation is expressed as the position in Figure 1.
When broken down into the two wheels 7 in A1 and A2, each becomes half the value of Q above. Also, in the above explanation, as shown in Figure 3 a,
In the case of A1・B=A2・B, A1・B≠
What will happen in the case of A2 and B? In addition,
FIG. 3 is a schematic representation of FIG. 1a. This will be explained with reference to FIG. 3b.
In the same figure, if the distance between positions A1 and A2 is divided by a perpendicular line from position B, it is m and n.
From the equilibrium conditions regarding the horizontal force that the system of the traveling platform 4 receives, the wheel 7A1 at position A1 and the position
Forces P1 and P acting on wheel 7A2 at A2
2 are respectively P1=(n/m+n)P and P2=
(m/m+n)P. As can be seen, the resultant force of the forces that the wheels 7A1 and 7A2 receive from the first guide rail at positions A1 and A2 is respectively Q ₁ = (n/m+n)P/
cos θ, Q ₂ =(m/m+n)P/cos θ. In short, there is a difference in the force received by each wheel.
This causes a difference in the lifespan of the radial ball bearings fitted into each wheel, which is inconvenient in practice. Now, the function of the above-mentioned force Q will be explained based on FIG. 2b. In this figure, each wheel 7A,
If the distance from the center of 7B to the center of each of the first guide rail 10A and second guide rail 10B is r,
The moment M that Q acts on the radial ball bearings 6A, 6B (not shown) fitted into the center of the wheels 7A, 7B is M=Qr sinθ=Pr
It becomes tanθ. Due to the above moment M, the radial ball bearing 6
The play will be eliminated. Moreover, as is clear from the above equation, this moment M is determined by the preload P, the distance r from the center of each wheel to the center of each guide rail, and the line connecting the centers of the first and second guide rails with the surface of the wheel. Since it is related to the angle θ formed, it can be said that there is a very large degree of freedom in design in order to select an appropriate value of the moment M. Moreover, in this embodiment, as already mentioned, each wheel 7A1, 7A2 attached to position A1, A2
Radial ball bearing 6A fitted into the center of
The magnitude of the moment acting on radial ball bearing 6B at position B is half that of the moment acting on radial ball bearing 6B at position B. This indicates that there is an imbalance in the calculated life of the radial ball bearing, which is disadvantageous in practice. The second and third embodiments, shown in side views of main parts as in FIGS. 4 and 5, improve the disadvantages of the first embodiment in terms of the life of the radial ball bearing. It should be noted that the parts and their numbers written in the above figures correspond to those in FIG. 1b, so the details will be omitted. In other words, in Fig. 4, all the wheels have the same diameter, but the size of the radial ball bearing fitted in the center is different from that at position B.
It is designed to be larger than those in A1 and A2 to equalize the life of the radial ball bearings. In addition, in the third embodiment shown in FIG. 5, the size of each radial ball bearing is the same, and the diameter of the wheel, more precisely, the distance from the center of the wheel to the center of the guide rail that contacts it, is at position A1. , the one at A2 is twice that at position B. In this way, the moment acting on each radial ball bearing is equalized, and the lifespan of each bearing is balanced. Although the second and third embodiments have been described in order to balance the life of the radial ball bearing, which embodiment is selected depends on design constraints. In other words, it is determined as appropriate based on the allowable space, the positional relationship with other related parts, and the like.

【Effect of the invention】

Owing to the structure and operation described above, the present invention has the following superior effects compared to conventional ones. (a) In order to run the traveling platform accurately and smoothly, the minimum wheel arrangement is adopted and the configuration is simple, so the weight of the traveling platform can be reduced and the dynamic characteristics can be improved. Therefore, for example, when this guide mechanism is used in a magnetic disk device, it has the effect of shortening the access time. (b) Since the magnitude of the moment that acts to take up the play in a radial ball bearing is determined by at least four factors, there is a large degree of freedom in design when selecting an appropriate moment. This has the effect of making the design very easy and making it possible to create a design that is close to the ideal. (c) By simply changing the dimensions of some parts without changing the basic structure, it is possible to balance the life of the radial ball bearings, which determine the life of this guide mechanism, for each wheel.

[Brief explanation of drawings]

Fig. 1: Plan view and side view of the first embodiment of the present invention, Fig. 2: An explanatory diagram of the forces acting on the main component parts of the first embodiment, Fig. 3: Under different conditions of the first embodiment. An explanatory view of force, FIG. 4; a side view of the main part showing the second embodiment; FIG. 5; a side view of the main part showing the third embodiment; FIG. 6; a three-sided view showing the conventional example. 4, 14, 24: Travel platform, 5, 15A, 15
B, 25A, 25B: Axle, 6, 16A, 16
B, 26A, 26B: Radial ball bearing, 7, 17
A, 17B, 27A, 27B: Wheel, 8: Spring, 10A, 10B: Guide rail.

Claims (1)

[Claims] 1. A pair of guide rails disposed parallel to each other and urged toward each other, each having a groove on its circumferential surface that engages with the guide rail, allowing play to occur. In a mechanism for movably guiding a traveling platform equipped with a plurality of wheels supported by bearings so as to be sandwiched between a pair of guide rails, the wheels are axially aligned with one of the pair of guide rails. Attach it to the traveling platform in a tilted position with respect to the plane that includes the axis, 1
A guide mechanism for a traveling platform, characterized in that play in the wheel bearing can be eliminated by a component of biasing force against the pair of guide rails based on the inclination. 2. In what is stated in claim 1,
A guide mechanism for a traveling platform, wherein the guide rail has a circular cross section. 3. A guide mechanism for a traveling platform according to claim 1 or 2, characterized in that the bearing is a radial ball bearing. 4. A guide mechanism for a traveling platform according to any one of claims 1 to 3, characterized in that the concave groove on the circumferential surface of the wheel is a V-groove. 5. In the product described in any one of claims 1 to 4, the number of wheels is three,
A guide mechanism for a traveling platform, characterized in that the triangle formed by the center of the wheel is an isosceles triangle, and one guide rail is installed parallel to one side that is not equilateral. 6 In what is stated in claim 5,
A guide mechanism for a traveling platform characterized by having three equal wheels and three bearings. 7 In what is stated in claim 5,
All three wheels have the same diameter, the two bearings located at both ends of the equal sides of the triangle are equal to each other, and the bearing located at the intersection of the equal sides has a lifespan approximately twice that of the two bearings. A guide mechanism for a traveling platform, characterized in that: 8 In what is stated in claim 5,
Traveling characterized in that all bearings are equal, the diameters of the two wheels located at both ends of the equal sides of the triangle are equal to each other, and the diameter of the wheel located at the intersection of the equal sides is approximately half the diameter of the two wheels. Guide mechanism of the stand.