JP2002323035A - Pinch roller device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and specific pinch roller device made at low cost into which a cylindrical resin bearing made of a resin material is pressed into the cylindrical pinch roller and rotatably mounted around a roller shaft. SOLUTION: The linear expansion coefficient of the resin material on an inside periphery 8 of the resin bearing contacting with the roller shaft 11 is made larger compared with that of a resin material that forms an outside periphery 9 of the pinch roller 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pinch roller device for compressing a capstan driven by forced rotation via a magnetic tape and controlling its transfer in a magnetic recording / reproducing apparatus. A specific configuration is also provided that allows for this.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional pinch roller device. This will be described below with reference to the drawings.

[0003] In FIG. 6, reference numeral 11 denotes a roller shaft having a tip whose diameter is smaller than that of the middle, and an end of a large diameter portion thereof is fixed to a pinch roller arm (not shown). Reference numeral 12 denotes a sliding bearing made of a resin material (hereinafter referred to as a resin bearing). Reference numeral 13 denotes a roller body in which an elastic layer 18 is formed on the outer periphery of a cylindrical sleeve 14 made of metal. It is rotatably mounted via a resin bearing 12.

The resin bearing 12 has a cylindrical shape having a through hole at the center of the shaft through which the roller shaft 11 can be inserted. The cylinder is fitted into the sleeve 14 from above and below with the resin bearing 12 substantially at the center. Shaped retaining member 1
5 and is fixed to the sleeve 14.

The resin bearing 12 fixed to the sleeve 14 is inserted into the small-diameter portion up to the end of the large-diameter portion of the roller shaft 11, and then the bush 16 is pressed into the small-diameter portion. And the end of the large diameter portion is rotatably held.

[0006]

However, in this configuration, the size of the pinch roller is reduced and the roller body 13 is moved.
When the diameter of the member is reduced, the retaining member 1
5 also needs to be reduced. Further, the gaps t1 and t2 between the inner diameter of the retaining member 15 and the outer diameters of the bush 16 and the roller shaft 11 become small, and there is a problem that the amount of automatic alignment for stabilizing the tape running is insufficient.

Therefore, instead of the conventional method of press-fitting the retaining member 15, a method of independently press-fitting the resin bearing has been attempted. However, since the material suitable for the resin bearing has a large linear expansion coefficient, the press-fitting is performed. It is necessary to increase the size of the interference fit, and if the size increases, the resin bearing may be shaved during press-fitting, or local pressure may concentrate on the center of the pinch roller after inserting the resin bearing, and the resin bearing after press-fitting may be used. The inner diameter dimension changes, causing variations in the self-alignment amount, which is the required performance of the pinch roller, and further affecting the outer diameter dimension of the elastic body on the outer periphery of the pinch roller, resulting in uneven thickness of the elastic rubber roll. Therefore, it has been difficult to satisfy the running stability of the tape, for example, a fluctuation in the speed of the tape occurs.

A resin material satisfying the durability and the self-aligning function, which are the basic performances of the resin bearing, is generally a material having a large linear expansion coefficient. In addition, a decrease in holding force due to stress relaxation due to creep is considered, and it is difficult to maintain the positional accuracy of the resin bearing by repeating the pinch roller pressing operation. As a result, the pressure in the width direction of the tape, which is the required performance of the pinch roller, does not act evenly, causing the tape to be stretched or the like, and it may be difficult to satisfy the running property of the tape.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has been made in consideration of the above-described problems. The pinch roller device is characterized in that it has a larger coefficient of linear expansion than the resin material to be used. Characteristic
Durability and running stability of the tape can be sufficiently satisfied, and a lightweight and compact pinch roller device can be realized.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a cylindrical resin bearing made of a resin material is press-fitted inside a cylindrical pinch roller, and the resin bearing is rotatably mounted on a roller shaft. In the attached pinch roller device, a linear expansion coefficient of a resin material of an inner peripheral portion of the resin bearing that is in contact with the roller shaft is larger than a linear expansion coefficient of a resin material of an outer peripheral portion that is in contact with the pinch roller. It is a pinch roller device characterized by the fact that although it is a pinch roller using a resin bearing, it exhibits an effective self-aligning function and has sufficient durability and tape running stability required characteristics of the pinch roller device. And a light and compact pinch roller device can be obtained.

According to a second aspect of the present invention, in the pinch roller, a stress relaxation preventing groove is formed at a position where the resin bearing is press-fitted and fixed, and the resin bearing bridges the stress relaxation preventing groove. 2. The pinch roller device according to claim 1, wherein said pinch roller device is press-fitted and fixed in a depressed state. It is possible to prevent a decrease in the press-fit holding force of the bearing.

According to a third aspect of the present invention, there is provided the pinch roller device according to the second aspect, wherein a side wall of the stress relaxation preventing groove is formed with an inclined surface. This facilitates press-fitting into the pinch roller.

According to a fourth aspect of the present invention, when the width of the stress relaxation preventing groove is b and the width of the resin bearing in contact with the roller shaft is c, c <b. 3. The pinch roller device according to claim 2, wherein the residual stress at the time of press-fitting does not cause local pressure on the resin at the inner peripheral portion of the resin bearing.

(Embodiment) The first aspect of the present invention will be described below.
An embodiment of the invention described in claim 4 will be described with reference to FIGS. 1 to 5. In these drawings, the same parts as those of the above-described conventional example are denoted by the same reference numerals.

The present embodiment is particularly different from the conventional example in that the cylindrical resin bearing 2 has a two-layer structure in which the inner peripheral portion 8 and the outer peripheral portion 9 are made of different resins. When the resin bearing 2 is tightly fitted with the sleeve 14 by press-fitting, the groove 5 for preventing stress relaxation due to creep of the resin bearing 2 is provided at a position where the resin bearing 2 of the sleeve 14 is fixed.

That is, the resin bearing 2 has a two-layer structure, and different materials are selected for the inner peripheral portion 8 and the outer peripheral portion 9, respectively. By using a resin having a high expansion coefficient, the original self-centering function of the pinch roller due to the elastic force of the resin is not reduced. The outer peripheral portion 9 which is in contact with the sleeve 14 of the pinch roller is made of a material having a small linear expansion coefficient in order to secure the press-fit holding force of the resin bearing.
When the resin bearing 2 is press-fitted, the resin bearing 2 can be easily press-fitted without excessively increasing the interference fit dimension to shown in FIG.

That is, in the double-layer bearing, different materials can be combined, and it is possible to provide a wide range of materials to satisfy the required performance. For example, since the bearing inner peripheral portion 8 needs a smooth rotation performance and an automatic alignment function by the elastic force of the resin, a material that does not use an additive such as glass is preferable, while the bearing outer peripheral portion 9 is press-fitted and held. Since a force is required, a material having a low coefficient of linear expansion is required.

Specifically, it is preferable that the inner peripheral portion 8 is made of polyethylene resin and the outer peripheral portion 9 is made of 25% polyacetal glass resin.

As described above, since a material having low linear expansion can be used for the outer peripheral portion 9, a sufficient pressure holding force can be obtained, and as in the conventional pinch roller device shown in FIG. Since there is no need for the retaining member 15, a lightweight and compact pinch roller device can be provided, and the cost can be reduced since the retaining member is not required.

If a 25% resin of polyacetal glass is used for the material selection of the outer peripheral portion of the bearing, a press-fit holding force can be obtained when the interference fit is 0.02 mm or more and 0.08 mm or less in the radial direction. It is possible to prevent the cylindrical elastic body 18 of the pinch roller from being defective in shape due to the press-fitting of the bearing, and it is also possible to prevent the resin from being scraped during the press-fitting.

Further, in the present embodiment, when the resin bearing 2 is tightly press-fitted and fixed to the sleeve 14,
The portion of the sleeve 14 where the resin bearing 2 is located
The groove 5 for preventing stress relaxation due to creep is provided. The stress relaxation preventing groove 5 is provided annularly so as to be located at the center of the mounted resin bearing 2, and the inner peripheral portion 8 of the resin bearing 2 is fixed so as to bridge the stress relaxation preventing groove 5. Have been.

The stress relaxation preventing groove 5 makes it possible to prevent the press-fit holding force of the resin bearing 2 from decreasing due to creep of the resin bearing material under severe conditions such as high temperature standing and temperature shock. This is because, as shown in FIG. 5, the outer peripheral portion 9 of the resin bearing repeats the process of expansion and contraction in accordance with the original linear expansion coefficient of the resin due to a temperature change. Since there is a difference in residual stress at the time of press-fitting between the portion at the position of the stress relaxation preventing groove 5 and the portion at the position of the stress relaxation preventing groove 5, a protrusion d is formed on the outer peripheral portion 9 of the resin bearing 2 due to creep. This projection d makes it possible to prevent a decrease in the press-fit holding force of the resin bearing 2. Therefore, the stress relaxation preventing groove 5 provided in the center portion prevents the resin bearing from being kept at a predetermined press-fitting position due to creep, and also improves the causes of uneven pressure in the tape width direction and tape elongation. Can be.

Further, in order to guarantee the bearing position accuracy due to creep, the stress relaxation preventing groove 5 provided in the sleeve 14 is provided.
In order to facilitate insertion when the resin bearing 2 is incorporated,
As shown in FIG. 2, the inclination angle α of the groove side wall is set to be inclined in the range of 0 ° <α ≦ 60 °.

As shown in FIG. 4, the width b of the stress relaxation preventing groove 5 is such that c <b with respect to a dimension c which is in contact with the roller shaft 11 of the resin bearing 2 and is effective for automatic alignment. This is set so that the residual stress at the time of press-fitting does not cause local pressure on the resin in the inner peripheral portion 8 of the resin bearing 2.

[0025]

As is apparent from the above description, according to the present invention, the performance of the pinch roller due to the elastic force of the resin is improved by using the resin having a large linear expansion coefficient for the resin bearing constituting the inner peripheral portion of the bearing. Without reducing the self-aligning function of
A stable state can be maintained. Also, by using a resin with a small coefficient of linear expansion for the outer periphery of the bearing,
A retaining member used for fixing a conventional bearing is not required, so that the size and weight of the pinch roller device can be reduced and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pinch roller device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the pinch roller device according to the embodiment;

FIG. 3 is a sectional view showing a state before press-fitting of the resin bearing of the pinch roller device according to the embodiment;

FIG. 4 is an enlarged sectional view of a main part of the pinch roller device according to the embodiment;

FIG. 5 is an enlarged cross-sectional view of main parts showing creep deformation of the resin shaft of the pinch roller device according to the embodiment.

FIG. 6 is a sectional view of a conventional pinch roller device.

[Explanation of symbols]

 2 Resin bearing 5 Stress relaxation prevention groove 8 Resin bearing inner peripheral part 9 Resin bearing outer peripheral part 11 Roller shaft 12 Resin bearing 13 Pinch roller 14 Sleeve 15 Retaining member 16 Bush 17 Capstan 18 Elastic layer

Claims (4)

[Claims] 1. A pinch roller device in which a cylindrical resin bearing made of a resin material is press-fitted inside a cylindrical pinch roller, and the resin bearing is rotatably mounted on a roller shaft. A linear expansion coefficient of a resin material of an inner peripheral portion in contact with the pinch roller is made larger than a linear expansion coefficient of a resin material forming an outer peripheral portion of the resin material in contact with the pinch roller. 2. A stress relaxation preventing groove is formed at a position of the pinch roller where the resin bearing is press-fitted and fixed, and the resin bearing is press-fitted and fixed with the stress relaxation groove being bridged. The pinch roller device according to claim 1, wherein 3. The pinch roller device according to claim 2, wherein a side wall of the stress relaxation preventing groove is formed by an inclined surface. 4. When the width of the stress relaxation preventing groove is b and the width of the resin bearing in contact with the roller shaft is c, c <b
The pinch roller device according to claim 2, wherein the pinch roller device is configured to satisfy the following relationship.