JPS594335B2 - Tape winding method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention eliminates the irregular winding phenomenon caused by air entrainment in the tape winding section of a winding device for tape-like objects such as magnetic tapes, and enables high-speed tape winding. The purpose is to provide a method (and apparatus) for

As shown in FIG. 1, the irregular winding phenomenon occurs when surrounding air is caught in a minute gap 3 formed between the take-up reel 1 and the tape 2 as the tape runs and the reel rotates.
In fluid lubrication theory, the tape 2 is
Floating blades (thick arrows in the figure) are generated, and in addition, irregular disturbances such as mechanical vibrations in the surrounding parts and fluctuations in tape tension due to eccentric rotation of the reel are added.
This is a phenomenon in which the tape vibrates in the width direction and the end surfaces of the wound tape become uneven.

If the tape is wound irregularly, it not only looks bad, but also causes curls in the tape, which causes frequent reading and writing errors in the magnetic head of the magnetic recording tape.

FIG. 2 shows the relationship between the floating edge F generated due to air entrainment, which is the fundamental cause of this irregular winding phenomenon, and the running speed u of the tape.

This shows that the floating edge of the tape increases as the tape running speed increases, due to a mechanism similar to that of hydrodynamic air bearings, indicating that the irregular winding phenomenon is an important factor that hinders high-speed tape winding. Recognize. To deal with the above-mentioned irregular winding phenomenon, in the conventional winding device, for example, (1) as shown in FIG. to prevent the tape from floating up.

(2) As shown in FIG. 4, a method has been used in which the edges of the tape 2 are regulated by side rollers 5 near the winding section to prevent the tape from shifting in the width direction.

However, according to the above method, the roller and the tape surface or the tape edge come into direct contact, which causes damage to the tape, and also has the disadvantage that dropouts occur due to the generation and adhesion of dust. Picking speed is 5-6
When it exceeds m/Sec, there is no longer any effect of preventing random winding, and high-speed winding is impossible.

Incidentally, if the tape tension is increased, the winding speed at which irregular winding occurs can be increased, but this is not preferable in the case of magnetic tapes because it causes peeling and deterioration of the magnetic layer.

In order to fundamentally eliminate the above-mentioned irregular winding phenomenon and enable high-speed tape winding, the present invention winds up the tape in a reduced pressure atmosphere. Examples and principles thereof are described below. This will be explained using figures.

FIG. 5 shows an embodiment of a tape winding machine to which the method of the present invention is applied. The tape 2 is supplied from a raw material 6, travels along respective traveling guides 7A, 7b, and 7c, passes through a processing section 8 such as cutting and gluing, and is wound onto a take-up reel 1. The entire winding device 9 is housed in a sealed container 10, and the pressure is reduced to below atmospheric pressure by an air pressure &ζ vacuum pump 11 in the sealed container. Next, the principle of winding the tape in a reduced pressure atmosphere using such a method eliminates the random winding phenomenon and enables high-speed winding. It was previously stated that the irregular winding phenomenon is due to a type of dynamic pressure air bearing effect due to the entrainment of air at the tape winding section.

The mechanism of pressure generation in a hydrodynamic air bearing is due to the viscosity of air, and the greater the viscosity, the greater the generated pressure. On the other hand, the viscosity of a gas does not change even if the pressure is lowered &ζ
This is what the kinetic theory of gas molecules shows. However, in the case of a compressible fluid such as air, due to the nonlinear nature of its pressure generation mechanism, the generated pressure decreases as the surrounding atmospheric pressure decreases. Specifically, the tape winding section is modeled, and as shown in Fig. 6, a narrow gap 12 is created in which the relationship a>b exists between the entrance clearance a and the exit clearance b.
When the two infinite-width planes 13a and 13b forming the space are moving at the same speed u in the direction indicated by the arrow in the figure, how is the distribution of the pressure p generated within the gap affected by the surrounding atmospheric pressure Pa? As a result of calculations using the differential method as a lubrication problem for compressible fluids, it was found that the generated pressure decreases as the ambient pressure Pa decreases, as shown in FIG.

Further, FIG. 8 shows the relationship between the ambient pressure and the generated floating blade by calculating the floating blade by integrating the pressure distribution shown in FIG. 7 and using the speed u as a parameter.

From Figure 8, as the ambient pressure decreases, the floating blade per unit width decreases, and when the ambient pressure is below 0.1 atm,
It can be seen that it is hardly affected by the speed u. The above are the results of simple model calculations, and in the case of an actual tape winding section, various factors such as tape width, tape tension, tape bending rigidity, etc. are added, and the situation is considered to be extremely complex. However, it is clear that the number of floating edges is basically reduced by lowering the ambient pressure.

As an example, as shown in FIG. 9, in a winding machine in which a decompression chamber is provided in the winding reel part, the width is 12.7v1 (1/2,
As a result of an experiment in which a magnetic tape with a thickness of 20 μm was wound onto a reel with the flange removed under a tape tension of 50 g, it was found that when the pressure in the decompression chamber is atmospheric pressure, the end surface of the wound tape becomes uneven (irregularities of 1u or more occur on the end face).

), at a winding speed of 6 to 7 m/Sec, the tape jumped out of the winding reel and was impossible to wind up. On the other hand, the pressure in the decompression chamber is set to 50t0rr (approximately 1/15at
m), even if the tape was wound at a high speed of 10 m/Sec, the end surface of the wound tape was extremely smooth, and as a result of measuring the unevenness of the end surface with a surface roughness meter,
The amount of misalignment between the end faces of individual layers of rolled-up tape is up to 0.04 mJ! It was about t. Also, when comparing tapes wound in the air and tapes wound in a reduced pressure atmosphere, tapes wound in a reduced pressure atmosphere have less slippage between each tape layer and are more resistant to vibrations and impact forces during transportation. It also has the advantage that the rolled shape is not easily disturbed.

In accordance with the principles detailed above, the present invention reduces the pressure around the tape winding section to below atmospheric pressure, suppresses the tape floating blade, which is the root cause of the uneven winding phenomenon, and achieves high-speed and stable tape winding. It is what makes it possible. In particular, reduce the air pressure around the winding section to 0.3
As can be inferred from FIG. 8, if the pressure is kept below atmospheric pressure, high-speed winding is possible, which was conventionally impossible in the atmosphere. Further, the lower the surrounding atmospheric pressure is, the smaller the floating blades generated will be, but if it is less than 1.times.10@-4 atmospheric pressure, the effect will not change much, which is rather unfavorable in terms of exhaust time and economy. In the embodiment of the present invention shown in FIG. 9, a decompression chamber 14 is provided around the take-up reel section, but the tape entrance section 16 through which the tape is introduced into the decompression chamber is exposed to the outside atmosphere. It is necessary to construct a seal to prevent large numbers of people from flowing into the decompression chamber.

There are various sealing methods.

Figure 10 shows two pinch rollers 1 on both sides of the tape 2.
7a17b is brought into pressure contact with the atmospheric pressure side 1 and the reduced pressure chamber side in a sealed manner. Further, in FIG. 11, a soft material 18 such as sponge rubber or cleaner tape is interposed in the gap between the tape in the tape entrance passage and the passage wall to suppress the inflow of gas into the decompression chamber. .

With magnetic tape, etc., damage to the tape surface can cause dropouts, so it is desirable to seal without contact.

A simple non-contact seal [ζ] is formed by providing a slit-like passageway with a gap approximately 10 to 100 microns larger than the thickness of the tape, as shown in Figure 12. In other words,
A narrow gap of 5 to 50μ on both sides of the tape 19a, 19
b, and the amount of flowing gas is suppressed by the viscous resistance of the gas. When a tape runs in such a narrow passage, the running position of the tape changes due to various disturbances, and there is a possibility that the tape comes into contact with the wall surface of the passage. In this case, as shown in FIGS. 13 and 14, the gap in the tape thickness direction of the tape passage is made larger on the atmospheric pressure side 1 and gradually (see FIG. 13) or in steps toward the decompression chamber side. By setting it small as shown in FIG. 14, it is possible to give rigidity to the tape running position and stably introduce the tape into the decompression chamber. This is partly due to the effect of hydrostatic bearings called step or surface aperture.
Furthermore, this is due to the effect of dynamic pressure bearings accompanying tape running. The same effect as described above can also be obtained by providing one or more pairs of grooves 21 on the upper and lower walls of the tape path, as shown in FIG.

Further, as shown in FIG. 15, one or more pairs of openings 20 are provided at opposing positions on two wall surfaces facing the tape surface of the tape path.
A double-sided facing type static pressure gas bearing may be constructed by providing an opening and blowing gas onto both sides of the tape.

Although Fig. 15 shows a discrete air supply type such as a self-generated iris or an orifice iris, a porous material is provided on the passage wall and gas is blown onto the tape surface through the porous material. A so-called porous static pressure gas bearing may also be constructed.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the irregular winding phenomenon, Figure 2 is a diagram showing the relationship between tape speed and tape floating blade, Figures 3 and 4 are explanatory diagrams showing conventional measures to prevent irregular winding, and Figure 5 is the method according to the present invention. An explanatory diagram of an example of a tape winding machine, Fig. 6 is an explanatory diagram of a model analysis of the random winding phenomenon, Fig. 7 is a pressure distribution diagram in the gap based on a model analysis of the same random winding phenomenon, and Fig. 8 is a model analysis. Fig. 9 is an explanatory diagram of an embodiment of the tape winding device according to the present invention, and Figs. 10 to 16 are diagrams showing the tape inlet to the decompression chamber of the tape winding device according to the present invention. It is an explanatory view of the sealing device of. 11... Vacuum pump, 14... Decompression chamber, 18... Soft material, 19a, 19b...
...Gap, 20...Opening.

Claims (1)

[Claims] 1. A method in which the tape is wound around the take-up reel by reducing and maintaining the pressure around the part where the tape is wound around the take-up reel to below atmospheric pressure. A tape winding method characterized in that the atmospheric pressure around the part is maintained at a reduced pressure of 0.3 to 0.0001 atm (absolute atmospheric pressure). 2. The tape is wound by placing the take-up reel part in a reduced pressure chamber, and reducing and maintaining the pressure in the reduced pressure chamber below atmospheric pressure using a gas discharge source such as a vacuum pump. tape winding device. 3. The tape winding device according to claim 2, characterized in that a sealing mechanism in which both sides of the tape are held between one or more pairs of rotating cylindrical bodies is installed at the entrance of the tape to the decompression chamber. 4. The tape winding according to claim 2, characterized in that a sealing mechanism that sandwiches both sides of the tape via a soft material such as sponge rubber or cleaner tape is installed at the entrance of the decompression chamber of the tape. removal device. 5. The tape winding device according to claim 2, wherein a slot-shaped tape passage having a gap 10 to 100 microns larger than the tape thickness is installed at the entrance of the tape to the decompression chamber. 6. A patent claim characterized in that a tape passage having a shape in which the size of the gap gradually decreases in a stepwise manner from the atmospheric pressure side toward the decompression chamber side is installed at the entrance of the tape to the decompression chamber. 2. The tape winding device according to item 2. 7 A double-sided facing type hydrostatic gas bearing is constructed by providing one or more openings at opposite positions of the wall facing both sides of the tape in the tape passage, and blowing gas onto both sides of the tape from the openings. A tape winding device according to claim 5, characterized in that: