JPS6110115A - Air-bearing type straight advance guide - Google Patents

Abstract

PURPOSE:To enable highly accurate straight advance guide by constructing a static pressure air-bearing in the direction perpendicular against the axis of two guides while opening the direction parallel with a plane to be formed by the axes of two guides. CONSTITUTION:The fixed shaft 11 which will be the reference of moving direction has circular cross-section and fitted with a movable carriage 12 through a movable bearing 15 having an orifice 14 for blowing the compressed air 13 while maintaining a bearing gap 16 of several mum thus to construct a static air-bearing with the fixed shaft 11 and th movable bearing 15 and to serve as a guide at the referential side. The fixed shaft 19 at the opposite side has U-shaped cross- section and fitted with a movable bearing 20 having rectangular cross-section. The direction (B)18 parallel with a plen to be formed by the axis of the fixed shaft 11 and the axis of fixed shaft which will serve as a guide at the opposite side is opened completely to never construct a static air-bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an improvement in an air bearing type linear movement guide used in a head carriage for a magnetic disk memory device.

[Background of the invention]

Taking advantage of the advantages of hydrostatic air bearings, such as the absence of static pressure, low friction, excellent straightness, and semi-permanent life, Bearings are used for relatively light loads (
Conventionally, when used for guiding a linear movement mechanism for several decoys, a structure as shown in FIG. 1 has been common. In other words, a shaft with a circular cross section arranged parallel to the moving direction is used as a fixed shaft 1, and a bearing hole is provided on a moving object 2 (to which the head is attached via an arm) and has an orifice 4 for blowing out compressed air 3. 5 were fitted together with a bearing clearance 6 of several μrn, forming a static pressure air bearing and moving. However, this structure had the following drawbacks.

(1) Connect the two fixed axes to the left and right I-lower 2 in the direction of movement.
Arranging and fixing the bearings parallel to each other (assembly/V-teru) is a very difficult task as the bearing clearance is small, and the larger the movement stroke, the more difficult it becomes.
Maintaining a perfect bearing clearance of several micrometers (a state in which the electrical resistance between the fixed shaft and the moving object is infinite) has been an obstacle to achieving the original performance of hydrostatic air bearings. Also, on the moving object side, it is important to machine the bearing holes parallel to the two axes in two directions with good dimensional and shape accuracy. The smaller the size, the more difficult it became, and it became the same obstacle. (2) Bearings consisting of a fixed shaft with a circular cross section and a movable hole (bearing hole) generally have equal rigidity in all directions. In order to provide uniform strength in all directions, both the fixed and moving sides have to be large, resulting in larger equipment, wasting material costs, and making it impossible to reduce the weight of moving objects, which is required for positioning control. Ta. Regarding static air bearings, for example, Japanese Patent Application Laid-open No. 1@54-1
It is described in Japanese Patent No. 55862.

[Purpose of the invention]

The present invention eliminates the drawbacks of the conventional air bearing type linear movement guide and provides a highly accurate and inexpensive hydrostatic air bearing type linear movement guide.

[Summary of the Invention] Hereinafter, an example will be shown in which the guide according to the present invention is applied to a head moving section related to a magnetic disk memory device. The head movement mechanism of a general magnetic disk memory device uses a rolling guide using steel balls or rollers. In order to increase the density of the device, it is necessary to examine how the reproduced signal is affected by the positional relationship between the recording track of the disk and the head while moving the head in steps of the order of 0.1 μm. The present invention was applied to the linear guide of a precision positioning mechanism for a carriage that carries the head and moves.

[Embodiments of the invention]

FIG. 2 is a perspective view showing one embodiment of the present invention. The fixed shaft 11, which serves as a reference for the moving direction, has a circular cross section. The moving carriage 12 is fitted onto a fixed shaft through a moving bearing 15 having an orifice 14 for blowing out compressed air 13, with a bearing gap 16 of several micrometers maintained. It is configured as a moving reference side guide. In the southern version, the hose that supplies compressed air and the head that is attached to the carriage via the arm are omitted.

The shaft and hole with a circular cross section in what constitutes the movement reference side guide are machined with sufficient accuracy using precision machining technology to maintain a gap of several μm, including dimensional tolerances, roundness of 2 cylindrical degrees, etc. Fixed axis 1 on the non-moving reference side located opposite to these
Reference numeral 9 has a U-shaped cross section, and a moving bearing 20 having a rectangular cross section is fitted therein. Due to the combination of square and U-shaped, the direction 17 perpendicular to the axial direction of the fixed shaft 11, which serves as the movement reference guide, is fixed with a gap of several μm so as to constitute a static air bearing. A direction (direction B) 18 parallel to the plane formed by the axis of the shaft 11 and approximately the axis of the fixed shaft, which is the non-moving reference guide, is
It is completely open and does not constitute a static air bearing. That is, it has sufficient rigidity in the A direction and no rigidity in the B direction. For this reason. Parallel alignment of the two fixed axes is completed by fixing the circular axis on the moving reference side and then performing only the above direction. The moving object side can also be machined using the circular bearing hole on the moving reference side as a reference, paying attention to the dimensional tolerance and parallelism only in the forward direction.

Also, the relationship between the fixed shaft and the movable bearing on the non-moving reference guide side is relative, and contrary to what is shown in Figure 2, there is also a structure in which the fixed shaft is square and the movable bearing side is U-shaped. However, if weight reduction of the carriage is important, the combination shown in FIG. 2 is advantageous. Furthermore, by changing the size of the bearing surface in the above-mentioned direction, the bearing rigidity is variable, and unlike the embodiment shown in Fig. 2, it is preferable to place more emphasis on bearing load capacity and pitting resistance than on yawing resistance. In case,
A combination as shown in FIG. 3, in which the direction of gravity coincides with the direction of gravity, can also be easily obtained. Figure 3 shows Figure 2 at 90
This is an example in which the moving axis is shaped like a U-shape, contrary to FIG. 2, and the bearing configuration direction is in the direction 17.

[Effects of the Invention] With the structure as described above, the following advantages can be obtained by the present invention.

(1) After fixing the fixed shaft on the movement reference guide side in a predetermined movement direction, on the non-reference guide side, it is only necessary to align the static pressure air bearing configuration direction (the above-mentioned direction) with the reference side, so the two fixed axes are parallel to each other. It became very easy to take out.

(2) The carriage (moving object) side also has 1 on the moving reference side.
After carefully and accurately machining a circular cross-sectional hole, it is only necessary to process the dimensional tolerance and parallelism in only six directions using that as a reference, and there is no need to pay attention to the parallelism of both axes.
Processing has become very easy. It is also now possible to adjust and fix while looking parallel to the A direction by creating a screw-separated structure at CC in Figure 2.

(3) Bearing rigidity is variable by changing the size of the bearing surface of the hydrostatic air bearing component, and by rotating the two axes by 90' with respect to the direction of gravity, emphasis is placed on yawing resistance. It is also possible to improve the load capacity and pitting resistance, and the range of application has expanded.In addition, in the above embodiment, the case where it is applied to a head carriage has been explained, but the present invention is not limited to this. Needless to say, it is widely applicable without any limitations.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating a conventional hydrostatic air bearing type linear movement guide, and FIGS. 2 and 3 are perspective views each showing an embodiment of the present invention. 7... Support and stand, 11... Fixed shaft, 12 - Carriage 513 - Compressed air, ] 4 - Orifice, 15...
- Moving bearing,] 6... Bearing clearance, 19... Non-moving reference side fixed shaft, 20... Moving bearing.

Claims (1)

[Claims] Of the movement guides composed of two axes parallel to the movement direction, one is the movement reference side and the other is the non-movement reference side, and the above 2
A static pressure air bearing is configured with a predetermined clearance in the direction perpendicular to the axial direction of the book guide, and an open bearing is not configured in the direction parallel to the plane formed by the axes of the two guides. Air bearing type linear movement guide characterized by: