JPS6021420B2 - air bearing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air bearing device that supports a magnetic tape by air blown out from microholes.

Originally, air bearings in magnetic tape devices have pressurized air inside, and by blowing the air out from micro holes in the bearing surface, an air gap of 40 to 50 mm thick is formed between the magnetic tape and the bearing surface. The magnetic tape is levitated.

Generally, the amount of levitation of a magnetic tape is determined by tape tension and air pressure applied to the surface of the magnetic tape. The air pressure applied to this magnetic tape surface is lower than the pressure of the pressurized air in the air bearing, and depends on the diameter and arrangement of the micropores in the bearing surface. In magnetic tape recording, in order to place the magnetic tape on a precise path, fluctuations in the amount of levitation of the magnetic tape on the air bearing IJ must be tolerably small, and also fluctuations in the tension of the magnetic tape and the pressure of pressurized air. It is necessary to do something small. Experiments have shown that the micropores of air bearings that satisfy these conditions have a hole diameter of 0.1 to 0.05 when the floating base of the magnetic tape is about 50 kites.
It was confirmed that the kite was tiny. However, it is difficult to create such minute holes in a relatively thick bearing surface by machining using a straight barrel drill or the like. In other words, the drilling ability with a drill is limited to drilling holes in a plate thickness that is five times the hole diameter, and when drilling multiple holes such as on an air bearing surface, there are problems such as drill wear and processing time. As a general rule of thumb for drilling micro-diameter holes, it is common to think that it is impossible to cut deeper than the hole diameter. Therefore,
If the hole diameter is 0.1 or 0.05, the thickness of the board that can be drilled with a drill will be extremely thin, such as 0.1 or 0.05. However, a thin mandle has contradictory problems in that it lacks rigidity and easily deforms, and the precise bearing surface is not constrained. Therefore, in order to avoid this problem, the tape was floated using a porous material with low transmittance as the secondary bearing surface, but this was extremely difficult to process and filled the holes when grinding or polishing the surface. There is a drawback that clogging occurs and the magnetic tape becomes non-uniformly arranged with respect to the bearing surface, resulting in non-uniform floating of the magnetic tape.

Other air bearing surfaces are shown in FIGS. 1 and 2.

FIG. 1 shows a configuration diagram of an air bearing, and FIG. 2 is a sectional view. The air bearing shown in Figures 1 and 2 is
A relatively large hole 2 that can be easily machined is formed in the side surface of a hollow cylindrical bearing support 1 with a thick side wall.
On the other hand, the thin plate 3 is provided with a minute hole 4 of 0.1 size or less, and the bearing support 1 and the thin plate 3 are fitted together so that the centers of the minute holes coincide with each other. However, in this structure, if the thickness of the thin plate is the same as or less than the hole diameter, it is possible to make micro holes by machining or etching, but in this case (1) even if it is a thin plate, Drilling a large number of small holes takes a lot of processing time and reduces efficiency.

(0) With the etching method, it is possible to make a hole with a hole diameter equal to or less than the thickness of the thin plate 3, and it has the advantage that it is easy to make the hole and the processing time can be shorter than with machining, but if the hole diameter is 0.
When the number of holes is less than one row, the accuracy of hole machining becomes poor and variations become large, and furthermore, some holes may not be formed on the bearing surface, making it difficult to form a uniform air film on the bearing surface.

Although the bearing support 1 is rigid and does not deform, the thickness of the thin plate 3 is the same as or smaller than the diameter of the microhole 4, so the thin plate 3 has poor rigidity and is easily deformed by the pressure of the pressurized air in the air bearing. deforms and is difficult to maintain the precise surface geometry required for air bearings. There are drawbacks such as.

The present invention eliminates the drawbacks of the air bearing in which a thin plate is bonded to the bearing support as described above, and provides an air bearing device that levitates the magnetic tape uniformly on the bearing surface and has less fluctuation in the amount of levitation. be.

The present invention will be explained based on the drawings.

FIG. 3 is a sectional view of a microhole portion of a thin plate forming a bearing surface of an embodiment of the air bearing device of the present invention.
To form the microholes, holes 8 are first formed in a relatively thin metal plate 6 such as a phosphor bronze plate by photoetching.
In this case, with the etching method, if the holes are made with a diameter smaller than the plate thickness, the precision of the holes will be poor and the variation will be large, so
Make the hole diameter more than double to avoid deterioration in hole machining accuracy. Next, when this thin metal plate 6 is subjected to electroless plating, a plating layer 7 is formed on both sides of the thin metal plate, and at the same time, a plating layer is also formed on the edges of the holes 8 formed by etching.

Plating is continued until the micropores 9 have the required diameter. Plating in this manner has the dual effect of increasing the plate thickness and increasing rigidity, and also reducing the diameter of the holes. In addition to the phosphor bronze plate mentioned above, any metal plate that is capable of electroless finishing can be used as the thin metal plate 6 that serves as a substrate for electroless finishing.

The type of electroless finish is not particularly limited, and any metal may be used as long as it is not difficult to reduce from an ionic state. Well-known examples include copper, nickel, nickel alloys (Ni-Co, Ni-Co-P, etc.), cobalt, cobalt alloys (Co-Fe-P, Co-W-P, etc.), chromium, tin, Examples include silver, gold, platinum metals (palladium, platinum, rhodium, ruthenium), and the like. Among these, especially cobalt and cobalt. Since aluminum, palladium, etc. are hard, they can form a plating layer that is hard to scratch, and other materials other than steel are chemically stable in the air, so they also have a rust-preventing effect on the bearing surface. Furthermore, since nickel alloys, cobalt, cobalt alloys, etc. are magnetic materials, there is a concern that they may affect the magnetic tape, but since the plating layer is thin and the coercive force of the magnetic tape is sufficiently large, the effect can be ignored. . The process of electroless plating will be explained using an example in which nickel plating is performed on a phosphor bronze plate.

First, the phosphor bronze plate is degreased, washed with water, and then palladium plated. Palladium plating is carried out by immersing a phosphor bronze plate in about 6 q of sand in a plating bath containing 0.1 part of palladium chloride and 10 parts of concentrated hydrochloric acid in the aqueous solution. Palladium plating is a necessary process as a catalyst for nickel plating.
After washing the palladium-plated phosphor bronze plate with water, it is immersed in nickel plating to perform nickel plating.
An example of a composition for nickel plating is: 1) In the aqueous solution, 30 parts of nickel sulfate, 10 parts of sodium hypophosphite (reducing agent), and 10 parts of sodium acetate (pH buffering agent, galvanizing agent).
It has an acidic character that is adjusted to an axis of 4.5 to 5.5 and maintained at around 90°C. As an example of such nickel plating, holes with a diameter of 0.2 wind are etched on a phosphor bronze plate with a thickness of 0.1 sail, and then electroless finishing is performed on the holes to a thickness of 0.05 sail. A thin plate with a thickness of 0.2 ribs and a hole of 0.1 rib diameter was obtained.

Other nickel baths and plating grades of other metals as exemplified above are also known; for example, they are also described in "Metal Surface Industry Complete Book, Electroless Scale Plating/Kamegami" (published by Yokoshoten, 1972). I will omit it because there is.

In creating the air supply holes of the air bearing according to the present invention, the first hole to be made can be larger than the required hole, so it is easy to make, the accuracy of the hole diameter is good, and the variation can be reduced. In the plating process, the plating layer follows the initial hole shape, so the accuracy of the hole diameter after plating is good. In particular, in the case of electroless nickel plating, the plating layer has a correlation with time, so the hole diameter of the air bearing can be controlled by the plating time. FIG. 4 shows an embodiment of the present invention, in which a thin plate having the structure shown in FIG. FIG. 3 is a configuration diagram of an air bearing joined together.

Further, FIG. 5 is a sectional view of the air bearing shown in FIG. 4. 1 is the same bearing support as shown in Figures 1 and 2, and has a pressurized air source inside, and holes 2 with large diameters are drilled on the side of the bearing support in the same arrangement as the holes in the thin plate. The same applies to the points mentioned above.

11 is the plated thin plate shown in FIG.

Experiments were conducted on the amount of magnetic tape levitation using the air bearing device according to the present invention, and it was found that the tape levitation could be achieved with little variation in air pressure and tape tension. For example, when the diameter of the air supply hole of the bearing device is 0.1 air, the air pressure is 500±low, the ship's day is 20, and the tape tension is 6.
．． The variation in the amount of levitation of the magnetic tape was 44±5 peaks relative to the variation in the skin. In this embodiment, a groove 10 is provided along the circumference on the side surface of the bearing support 1, and a thin plate 11 is bonded to the groove by filling the groove with an adhesive.

By providing the grooves in this manner, uniform bonding between the bearing support 1 and the thin plate 11 can be achieved. As explained above, according to the present invention, by plating a thin plate in an air bearing, the hole diameter is controlled, a long precision hole is formed, and the plate thickness is thickened so that it is not deformed and has a hard air bearing surface. Air bearing refitting can be achieved.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an exploded view showing a conventional bearing device, FIG. 2 is a sectional view of the bearing device shown in FIG. 1, FIG. 3 is a sectional view of a small hole in a thin plate according to the present invention, FIG. 4 is an exploded view showing one embodiment of the air bearing device of the present invention, and FIG. 5 is a sectional view of the bearing rhombus shown in FIG. 4.

In the figure, 1 is a bearing support, 2 is a hole in the bearing support, 3 is a thin plate, 4 is a small hole in the thin plate, 5 is a tape, 6 is a metal board, 7 is a plating layer, 8 is a small hole in a thin metal plate, 9 represents a microhole after plating, 10 represents a groove, and 11 represents a thin plate after plating.

2nd figure Figure 3 Figure 1 Figure 4 Figure 5

Claims (1)

[Claims] 1. A thin plate with micro holes drilled in the same arrangement as the holes is placed on the side surface of the bearing support body, which has a hollow cylindrical side surface with a large number of relatively large diameter holes, so that the holes and the micro holes correspond to each other. In an air bearing device in which air is jetted from the inside of the bearing support through micro holes and the tape is suspended and supported by the air film, the thin plate has micro holes with a diameter larger than the required size. An air bearing device characterized in that a drilled thin metal plate is subjected to electroless plating until the minute holes reach the required diameter.