JPH06259844A - Stationary cylinder made of resin - Google Patents

Abstract

PURPOSE:To improve a sliding characteristic by forming the stationary cylinder of molded articles of a resin added with a conductive material, exposing this conductive material onto the sliding surface of the stationary cylinder with a magnetic tape and specifying the surface shape of the sliding surface to Ra>0.4. CONSTITUTION:Polycarbonate(PC) is adopted as the base material of the resin to be used and the conductive material added with carbon fibers(CF) is used as the conductive material. The amt. of projection of the CF on the sliding surface of the cylinder and the surface shape of the sliding surface are adjusted by the amt. of the CF to be added and the molding conditions of the cylinder. The relation between the size of the surface shape adjusted by the exposure of the CF and the coefft. of friction is such that the coefft. of friction is confined approximately within 0.2 to 0.3 in an Ra>0.4 range. This coefft. of friction is equal to the coefft. of friction in the case of an aluminum material or below and is confined within a practicable use range. As a result, the increase in the coefft. of friction is obviated by exposing the conductive material added within the resin to the sliding surface until the surface shape of the sliding surface attains Ra>0.4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for improving the slidability of a resin-made fixed cylinder for the purpose of cost reduction, size reduction and weight reduction in a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art In recent years, due to the demand for cost reduction of magnetic recording / reproducing mechanism parts, resin research of each part has been widely conducted, and the progress of practical application is remarkable, and many inventions and inventions have been proposed. ing. For example, guide rollers for guiding the magnetic tape to a predetermined traveling path, a mechanical chassis for holding the entire mechanical components, and a cylinder base for holding the cylinder at an arbitrary angle have already been made into resin and have been put to practical use. As a result, the cost can be significantly reduced compared to the parts before being made into resin, and further contributes to weight reduction.

Further, recently, researches for resinification of cylinders, particularly fixed cylinders, which are the heart of the magnetic recording / reproducing apparatus, have been actively conducted.
Many inventions have been proposed, such as 1B5 / 52 102). This type of magnetic recording / reproducing fixed cylinder plays a role of accurately moving the magnetic tape to a predetermined position, and it is said that the frictional force between the magnetic tape and the fixed cylinder must be minimized. In order to maintain the characteristics of such frictional force in the conventional fixed cylinder using aluminum material,
The surface roughness of the sliding surface of the magnetic tape was set to about 1S to 3S and the cutting was performed, and the friction coefficient was set to about 0.25 with respect to the coating type magnetic tape.

Even in the resin type fixed cylinder, it is necessary to make the friction coefficient as small as possible like the aluminum material. Therefore, there are problems to be studied such as development of a material having excellent friction characteristics or optimization of the surface shape of the sliding surface. It was happening. That is, in the fixed cylinder, it is necessary to obtain high dimensional accuracy in addition to friction. Therefore, it is at least necessary to use a material that has high dimensional accuracy, that is, a material having a small molding shrinkage rate.

However, since all materials having a small molding shrinkage ratio have a high friction coefficient and cannot stably run the magnetic tape, it is necessary to take measures to obtain a desired friction coefficient by optimizing the surface shape. There was a problem.

Further, since the fixed cylinder for the magnetic recording / reproducing apparatus requires frictional characteristics, sticking of the tape due to static electricity generated when sliding relative to the magnetic tape must be prevented. In the conventional fixed cylinder, the base material is an aluminum material with excellent conductivity, so it is possible to suppress the static electricity generated when the magnetic tape slides, and at the same time, generate a small amount of static electricity to the ground via the cylinder base. I was able to deal with it by making it a structure that drops it.

In the resin-made fixed cylinder as well, there have been many proposals to add conductivity to the base material to add conductivity to the base material in order to eliminate this charging phenomenon. However, resin molded products always have a surface layer called a skin layer, so if the conductive agent added in the surface is filled, the cylinder surface that comes into contact with the magnetic tape becomes the resin surface of the insulator. Can no longer be prevented.

In addition, even when a conductive material is projected from the surface layer to impart conductivity, the resin of which the surface of the magnetic tape is an insulator other than the conductive material depending on the amount of projection or the shape of the projected surface. Depending on the rate of contact with the base material, the amount of static electricity generated is larger than that of a conventional aluminum material, which is a 100% conductive material, and there is a problem in that running failure of the magnetic tape occurs.

Further, as described above, in the resin-made fixed cylinder, since the base material cannot be made of 100% conductive material, there is a drawback that the generated static electricity cannot be grounded.

These problems caused by static electricity appear as a phenomenon in which the friction coefficient increases with the number of times (time) the magnetic tape slides, and eventually the tape sticks to the cylinder. Therefore, in order to obtain the above-mentioned desired friction coefficient, even if the surface shape of the sliding surface of the magnetic tape is optimized, the friction coefficient rises depending on the number of times of sliding (time) unless charging is prevented, and eventually the tape becomes There is a problem that the magnetic tape sticks to the cylinder and the magnetic tape cannot run.

As described above, reducing the friction coefficient to prevent the friction coefficient from increasing due to electrification or the sticking of the magnetic tape is a problem of the resin-made fixed cylinder, which is a major obstacle to practical use. Was there.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and eliminates the increase in the friction coefficient when the fixed cylinder of the magnetic recording / reproducing apparatus is made of resin and the friction coefficient due to static electricity. However, the object is to obtain a resin-made fixed cylinder having excellent slidability.

[0013]

The present invention relates to a fixed cylinder which is mounted on a magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic tape and which guides the magnetic tape by its outer peripheral surface and a lead groove. Is a molded body made of a resin to which a conductive material is added, and the added conductive material is exposed on the sliding surface of the fixed cylinder with the magnetic tape,
The surface shape of the sliding surface is Ra> 0.4.

[0014]

According to the above construction, the contact area between the surface of the magnetic tape and the resin base material which is the insulating material is reduced, and it is possible to prevent the generation of static electricity in an amount that leads to defective running of the magnetic tape. Therefore, the increase in the friction coefficient due to the electrification of the resin-made fixed cylinder is eliminated, and the sticking of the magnetic tape does not occur.

Further, by setting Ra> 0.4, the friction coefficient becomes a small value that can be practically used. Therefore, the friction coefficient is small, and the resin is made of resin without increase of the friction coefficient due to electrification or sticking of the magnetic tape. It is possible to provide a fixed cylinder.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a resinized fixed cylinder of the present invention will be described in detail below with reference to the drawings.

First, as the resin used here, polycarbonate (hereinafter referred to as PC) was adopted as a base material, and carbon fiber (hereinafter referred to as CF) was added as a conductive material. Further, the amount of protrusion of CF on the sliding surface of the cylinder and the surface shape of the sliding surface are adjusted by the amount of CF added and the molding conditions of the cylinder.

Table 1 shows the amount of CF added and the surface shape (roughness) of the sliding surface of Samples A to E of the resinized fixed cylinder used in this example.

[0019]

[Table 1]

The shapes of the sliding surfaces of Samples C, D and E are shown in FIGS. 3 to 5, respectively. Here, the sample C is shown in FIG.
As shown in Fig. 6, CF has a structure in which CF is embedded in the skin layer that is usually formed by molding a resinized fixed cylinder, and the shape of the sliding surface depends on the shape of PC, which is an insulator, like Sample A and Sample B. To do.

FIG. 2 is a diagram showing changes in friction coefficient with respect to the tape running time of the samples A to E and a conventional fixed cylinder (shown as an aluminum material in the figure) using an aluminum material as a base material. In the figure, samples A and C have a large initial friction coefficient, and further increase with the passage of running time. Although the initial friction coefficient of Sample B was suppressed to a practical level by adjusting the surface shape, the surface was made of PC alone, so the friction coefficient also increased with the passage of running time, and the friction of a practical level increased. The coefficient cannot be maintained, and the degree of increase is the same as in sample A,
Greater than C. Sample D has a slightly large initial friction coefficient and a small CF protrusion amount (exposure amount to the cylinder surface), so that the friction coefficient increases with the elapse of the running time, but the ratio is moderate.

On the other hand, in comparison with Samples A to D, Sample E has a large amount of protrusion of CF, and the initial friction coefficient is suppressed to a practical level. Moreover, the friction coefficient hardly changes with the passage of the tape running time. And this characteristic is very similar to the characteristic of the conventional fixed cylinder made of aluminum.

From the above results, it is clear that the increase in the friction coefficient is due to whether or not CF, which is a conductive material, is exposed on the surface, which is one of the causes of the generation of static electricity during sliding. It is considered to be a factor.

FIG. 1 shows the relationship between the friction coefficient and the size of the surface shape manipulated by the exposure amount of CF. R in the figure
In the range of a> 0.4, the coefficient of friction is approximately within the range of 0.2 to 0.3, which is equal to or less than the coefficient of friction of the conventionally used aluminum material. It can be said that As described above, the friction coefficient value and its rising characteristic, which have been a problem when the fixed cylinder of the magnetic recording / reproducing apparatus is made of resin, are such that the surface shape of the sliding surface is Ra> 0.4 as in the present embodiment. This can be solved by exposing the conductive material added to the resin to the sliding surface.

In this embodiment, in order to expose the conductive material on the sliding surface, the amount of the conductive material added and the molding conditions were adjusted. However, as another method, the skin layer is destroyed by a certain means. Then, a similar effect can be expected by this method. Further, the increase in the friction coefficient due to static electricity can be solved even if the resin material other than PC is configured in the same manner as this embodiment.

On the other hand, when molding a resin-fixed fixed cylinder, the occurrence of tape damage due to abrasion of the material at the initial stage of sliding between the cylinder and the magnetic tape is a problem.

This is because minute projections peculiar to the material used for molding or a molding method such as a molding method are generated on the surface of the resin molding cylinder, and these minute projections are scraped off at the initial stage sliding between the fixed cylinder and the magnetic tape. The scraped abrasion powder accumulates between the surface of the resin-made fixed cylinder and the magnetic tape and slides to damage the tape.

FIG. 6 is a diagram showing the results of the sliding characteristics test between the resin-made fixed cylinder and the magnetic tape. The friction coefficient during the initial sliding of about 1 minute is drastically reduced. As can be seen, this means that the minute projections of the material on the surface of the fixed cylinder, which had caused the increase in the friction coefficient, are gradually scraped off by sliding with the magnetic tape. In addition, from about 1 minute after the start of sliding in the initial stage, 3
The sliding coefficient was constant up to 00 hours, which means that the surface of the resin-made fixed cylinder became smooth.

It can be said that the tape damage that occurs during the initial sliding between the resinized fixed cylinder and the magnetic tape is a great obstacle to the resinification of the fixed cylinder at a practical level.

FIG. 7 shows a state of the magnetic surface of the magnetic tape immediately after the friction coefficient becomes constant. However, the linear magnetic layer peels at several places in the tape running direction, and peels around it. It is easy to see how the magnetic powder is scattered.

Next, FIG. 8 shows the sliding characteristics when a sliding test is carried out for about 1 minute, only the magnetic tape is replaced with a new one, and the sliding test is carried out again. As can be seen by comparing this figure with FIG. 6, the coefficient of friction is constant immediately after the start of sliding. Further, the appearance of the magnetic surface of the magnetic tape after the sliding test at this time is shown in FIG. 9, but the damage as shown in FIG. 7 has not occurred.

From the results of this experiment, it is confirmed that the fine projections generated on the surface of the cylinder after molding are scraped off during the initial sliding of the fixed resin cylinder and the magnetic tape, and the surface of the fixed resin cylinder becomes smooth. It can be considered that the friction coefficient is reduced by the above, and the friction coefficient becomes constant due to the complete disappearance of the minute protrusions.

Regarding the tape damage, the minute projections on the surface of the resin-made fixed cylinder are scraped off by the sliding in the initial stage, and the abrasion powder scraped off is accumulated between the resin-made fixed cylinder and the magnetic tape. It is considered that the abrasion powder scrapes off the magnetic tape magnetic layer by repeating sliding with the abrasion powder interposed, which causes tape damage. Therefore, it can be predicted that the magnetic tape will be damaged if the resin-made fixed cylinder as it is molded is incorporated into the magnetic recording / reproducing apparatus.

Then, the magnetic tape is slid for several minutes in order to remove fine projections of the material generated on the surface of the resinized fixed cylinder as it is molded, and after this step, the resinized fixed cylinder is magnetically recorded. I decided to incorporate it in the playback device.

By doing so, it becomes possible to provide a resinized fixed cylinder having a constant friction coefficient immediately after the start of tape sliding as shown in FIG. Needless to say, the resin-made fixed cylinder at this time is one in which the conductive material is exposed on the surface and the surface shape is adjusted to Ra> 0.4 as described above.

In the above method, the magnetic tape is slid as means for removing the minute protrusions of the resin-made fixed cylinder. However, the minute protrusions can be removed by other means such as ultrasonic polishing. . In short, it suffices that the tape damage in the initial sliding can be eliminated, and whether or not the fine protrusions disappear can be determined by whether or not the friction coefficient is stable.

[0037]

As described above, according to the present invention, the friction coefficient and the increase in the friction coefficient due to static electricity, which have been problems when the fixed cylinder of the magnetic recording / reproducing apparatus is made of resin, are eliminated, and slidability is improved. It is expected that an excellent resinized fixed cylinder can be provided with a simple structure.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a surface shape and a friction coefficient of a resinized fixed cylinder according to the present invention.

FIG. 2 is a diagram showing a change in friction coefficient with respect to a tape running time between each of the tested sample resinized fixed cylinders and a conventional fixed cylinder made of an aluminum material.

FIG. 3 is a diagram showing a surface shape of a sample C in FIG.

FIG. 4 is a diagram showing a surface shape of a sample D in FIG.

5 is a diagram showing a surface shape of a sample E in FIG.

FIG. 6 is a diagram showing a relationship between a tape sliding time and a friction coefficient of a conventional resin-made fixed cylinder.

FIG. 7 is a diagram showing a surface shape of a conventional resin-made fixed cylinder after initial sliding.

FIG. 8 is a diagram showing the relationship between the tape sliding time and the coefficient of friction of the resinized fixed cylinder of the present embodiment.

FIG. 9 is a view showing a surface shape of the resin-fixed fixed cylinder of this embodiment after sliding.

Claims (1)

[Claims] 1. A fixed cylinder which is mounted on a magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic tape and which guides the magnetic tape by its outer peripheral surface and a lead groove, wherein the fixed cylinder is made of a resin to which a conductive material is added. As a molded body, the added conductive material is exposed on the sliding surface of the fixed cylinder with the magnetic tape, and the surface shape of the sliding surface is Ra.
Resinized fixed cylinder characterized by> 0.4.