JP2000156001A - Pinch roller and pinch roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wear or burning of a shaft, to facilitate its forming and to improve its dimensional precision by preparing gaps which are opened in at least one side of end surface between an inner cylinder and an outer cylinder of a bearing which is disposed between the shaft and a sleeve. SOLUTION: An inner cylinder 3 and an outer cylinder 5 of a bearing 20 are connected with plural connecting ribs 9b in the axial direction, and gaps 7b in the axial direction are provided in parts which are partitioned with the connecting ribs 9b. The gaps 7b are opened in both end surfaces of the bearing 20. The gaps 7b gradually become large from one side of the end surface toward the other side of end surface opening part in order to facilitate mold releasing. The bearing 20 is provided with elasticity by preparing the gaps 7b between the inner cylinder 3 and the outer cylinder 5. Also, since the bearing 20 is made thin by preparing the gaps 7b, a shrinkage deformation after forming is reduced, high roundness is secured and also a partial pressure is hardly exerted at the time of aligning. A position of the connecting rib and the number of the connecting rib in the axial direction are suitably decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pinch roller and a pinch roller bearing used in a tape drive of a video tape recorder, an audio tape recorder, or the like.

[0002]

2. Description of the Related Art Conventionally, a pinch roller used in a tape drive device is used to reliably transfer a tape running between a capstan motor shaft in a stable state.
A bearing having an automatic centering action so as to follow the inclination of the capstan motor shaft is used. In recent years, sliding bearings such as metal bearings and resin bearings have been used for these bearings instead of ball bearings. As such a bearing, for example, a bearing described in Japanese Utility Model Publication No. 8-9447 and Japanese Patent Application Laid-Open No. 7-65543 has been proposed. Although such a bearing can reduce the cost, it has the following problems in manufacturing and use.

[0003]

The metal bearing has a problem that the pinch roller shaft to be mounted is worn or seized due to its hard material. When the shaft is worn, not only does the clearance become large and the smooth rotation of the pinch roller is hindered, but also the fine powder generated by the abrasion adheres to the device or tape and exerts an adverse effect.

On the other hand, in the resin bearing, as described in the above-mentioned publication, the inner diameter of the bearing is increased toward a straight central portion with a clearance between the bearing and the shaft, and toward an end in order to have an automatic centering action. It is formed in a crowning shape whose diameter gradually increases. Thus, even if both ends of the inner diameter are enlarged, injection molding can be easily performed by a split mold that pulls out the nest to both sides, but in a resin bearing, molding by a split mold is preferable to maintain dimensional accuracy. Absent. For this purpose, the integrally formed nest must be forcibly pulled out to one side.
If it is forcibly removed, a hard resin is used, which may cause cracking or chipping. In addition, since the whole is thick, shrinkage after molding may deteriorate dimensional accuracy (particularly roundness). Further, in the case of the cutting molding, there are problems that it takes a lot of man-hours to mass-produce, and that the cost increases.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and not only prevents abrasion and seizure of a shaft, but also facilitates molding, has excellent dimensional accuracy, and a pinch using the bearing. Rollers are provided.

[0006]

The present invention has the following configuration to achieve the above object. That is, the pinch roller according to the present invention comprises a shaft fixed to a frame, a sleeve having a rubber roller on the outer periphery, and a bearing disposed between the shaft and the sleeve, wherein the bearing is an inner cylinder and an outer cylinder. And a space opened at at least one end face between the inner cylinder and the outer cylinder to provide elasticity. The length of the bearing is preferably equal to or less than half the axial length of the rubber roller. In addition, the pinch roller bearing according to the present invention includes an inner cylinder and an outer cylinder, and is provided with a gap that opens on at least one end surface between the inner cylinder and the outer cylinder, so as to have elasticity. And The inner cylinder and the outer cylinder may be connected by an axial and / or radial connection rib, or the inner cylinder and the outer cylinder may be connected by a radial connection rib at an end, and the gap may be connected to the other end. May be formed so as to be opened at the end surface of the.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The illustrated embodiment will be described below in detail. First, the pinch roller bearing according to the present invention will be described.
The bearing 20 connects the inner cylinder 3 and the outer cylinder 5 by a plurality of connecting ribs 9b in the axial direction, and provides an axial gap 7b in a portion partitioned by the connecting rib 9b.
Are open at both end surfaces of the bearing 20. The gap 7b is
In order to facilitate die-cutting, the width gradually increases from one end face toward the other end face opening.

The bearing 20 has elasticity due to a gap 7b provided between the inner cylinder 3 and the outer cylinder 5. In addition, the provision of the voids 7b makes the wall thin, so that there is little shrinkage deformation after molding, and high roundness can be secured.
Further, since the bearing 20 has elasticity by the space 7b, partial pressure is not applied even when the centering operation is performed, and wear of the pinch roller shaft or the bearing itself is prevented. The number of the connecting ribs 9b is not particularly limited, but is preferably provided at uniform intervals as a whole.

FIG. 3 shows another embodiment of the bearing according to the present invention. The bearing 20a is provided with an outer cylinder 5 with an axial gap 7c provided outside the inner cylinder 3, and the inner cylinder 3 and the outer cylinder 5 are provided with radial connecting ribs 9 provided on one end face. And open at the other end surface to form a U-shaped cross section. The gap 7c gradually increases toward the end face opening to facilitate die cutting.

The inner diameter of the inner cylinder 3 is larger at both ends than at the center in the radial direction. That is, the central portion 3a is formed in a linear shape having a certain clearance between the central portion 3a and the pinch roller shaft, and the end portions 3b are formed from both sides of the central portion 3a.
The diameter gradually increases in the radial direction toward, and is formed in a tapered shape or an arc shape having a difference t. As described above, even in a configuration in which the inner diameter of the inner cylinder 3 is gradually increased in the radial direction from the center to the both ends, the gap 7c is provided between the inner cylinder 3 and the outer cylinder 5 to form the inner cylinder 3. At this time, even if the nest is forcibly removed, there is no risk of cracking or chipping.

FIG. 4 shows a third embodiment of a bearing according to the present invention. A bearing 20b connects an inner cylinder 3 and an outer cylinder 5 at a central portion by radial connecting ribs 9a and opens at both end surfaces. An axial gap 7a is provided. When the connecting rib 9a is provided at the center in this way, the elasticity at both ends can be made uniform. Also in this embodiment, the central portion 3a of the inner diameter of the inner cylinder 3 is formed in a linear shape having a certain clearance between the inner cylinder 3 and the pinch roller shaft, and is radially directed from both sides of the central portion 3a toward the end 3b. The diameter is gradually increased to form a tapered shape or an arc shape having a difference t.

[0012] The pinch roller bearing according to the present invention comprises:
The present invention is not limited to the above embodiment, and the positions of the radial connecting ribs connecting the inner cylinder 3 and the outer cylinder 5 and the number of the axial connecting ribs can be appropriately determined. They can be used in appropriate combinations.

Next, a pinch roller according to the present invention will be described with reference to FIG. The pinch roller 21 is made of rubber whose outer peripheral surface is polished in advance. A rubber roller 23 having elasticity is attached to an outer peripheral surface of a metal sleeve 25, and a bearing 20 a is provided at an appropriate position on an inner peripheral surface of the sleeve 25. The stepped pinch roller shaft 29 fixed to the frame 27 is inserted into the bearing 20a, and is fixed by the end cap 30.

When the stepped pinch roller shaft 29 is inserted into the bearing 20a, a washer 31 made of synthetic resin is provided between the stepped portion of the shaft 29 and the end cap 30 at the upper and lower end surfaces of the bearing 20a in the axial direction. Insert A predetermined axial clearance is provided between the washer 31 and the stepped portion of the shaft 29 and the end cap 30.

The pinch roller 21 having the above-mentioned structure is attached to an appropriate position of a tape drive such as a video tape recorder by a frame 27. The rubber roller 2 contacts the tape and presses the tape to the capstan motor shaft.
3 is disposed parallel to the capstan motor shaft.
During use, the rubber roller 23 is pressed by the capstan motor shaft to transfer the intervening tape. Since the bearing has an air gap, it can easily follow the inclination of the capstan motor shaft to ensure stable tape feeding, and there is no fear of shaft wear due to local pressure or the like. Further, when the inner diameter is formed in a tapered shape or an arc shape gradually increasing in the radial direction from the center to the end, the inclination of the capstan motor shaft can be more easily followed.

Although the case where the bearing 20a shown in FIG. 3 is used for the pinch roller 21 has been described, the bearing of any embodiment can be used. The axial length of the inner cylinder forming the bearing is described in claim 1 as being not sufficiently smaller than the axial length of the rubber roller, but in claim 2, FIG. As described, when the length is sufficiently smaller than the axial length of the rubber roller, that is, when the axial length of the inner cylinder that forms the bearing is equal to or less than half the axial length of the rubber roller. Is described.

Assuming that the clearance between the inner cylinder and the shaft is constant, if the axial length of the inner cylinder is less than half the axial length of the rubber roller, The self-centering function is inevitably greater than when the lengths of the rubber rollers in the axial direction are the same. Therefore, when the axial length of the inner cylinder that forms the bearing is set to be equal to or less than half the axial length of the rubber roller, the inner diameter of the inner cylinder increases in the radial direction from the center to the end. It is not necessary to form it into a tapered shape or an arc shape that gradually expands its diameter.

[0018]

EXAMPLE Next, a pinch roller using a bearing according to the present invention was used as an example, and a pinch roller using a conventional bearing was used as a comparative example, and a shaft wear (life) test was performed. The comparison result of the test will be described. The bearing according to the present invention is made of a polyacetal-based resin, and the structure of FIG. 2 and FIG. 3 is referred to as Example 1, and the structure of FIG. Further, in the comparative example, a pinch roller using a metal bearing shown in FIG. 6A formed in a crowning shape in which the inner diameter gradually increases toward the end is used as a comparative example A, and the inner diameter is formed straight. 6 (b)
Comparative Example B was a pinch roller using a polyacetal resin bearing shown in FIG. The size is 3m inside diameter
m, outer diameter 7 mm, length 6 mm.

The test was performed under the following conditions. 1. Pressing force of the pinch roller to the capstan motor shaft
The rotation speed of the 5 kgf capstan motor shaft was set to 1270 rpm, which is approximately 7 times the rotation speed of the reproduction mode by the video tape recorder, and the rotation direction was reversed every 15 minutes. The test results are as shown in Table 1. In the comparative example, the shaft was slightly worn, but in each of the examples, the shaft was not worn at all.
The lack of abrasion in the embodiment is presumably because no local pressure is applied. Further, the bearing has a certain elasticity due to the formation of the gap, and can easily follow the inclination of the capstan motor shaft.

[0020]

[Table 1]

[0021]

As is apparent from the above description, since the inner tube and the outer tube are connected to each other and a space is provided on at least one end surface, shrinkage after molding is small and dimensional accuracy is maintained. Can be. In addition, the manufacturing is easy, the cost of the pinch roller can be reduced, and the function as the pinch roller does not deteriorate. Further, with the above-described structure, the pinch roller shaft is less worn and the tape can be stably transferred.

[Brief description of the drawings]

FIG. 1 is a perspective view of a bearing according to a first embodiment.

FIG. 2 is a longitudinal sectional view in the radial direction of FIG. 1;

FIG. 3 is an axial longitudinal sectional view showing a second embodiment.

FIG. 4 is an axial longitudinal sectional view showing a third embodiment.

FIG. 5 is a sectional view of a pinch roller according to the present invention.

FIG. 6 is an axial sectional view of a bearing showing a comparative example.

[Explanation of symbols]

 Reference Signs List 3 inner cylinder 3a center part 3b end part 5 outer cylinder 7, 7a, 7b, gap 9, 9a, 9b connecting rib 20, 20, a, 20b bearing 21 pinch roller 23 rubber roller 25 sleeve 27 frame 29 stepped shaft 30 end cap 31 washer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kozo Ishihara 12-32 Taisei-cho, Neyagawa-shi, Osaka Japan Science and Metallurgy Co., Ltd. Co., Ltd. (72) Inventor Toshihiro Okada 1 Nobesawa, Kaisei-cho, Ashigara-gun, Kanagawa Pref.

Claims (5)

[Claims] 1. A shaft fixed to a frame, a sleeve having a rubber roller on an outer periphery, and a bearing disposed between the shaft and the sleeve, wherein the bearing comprises an inner cylinder and an outer cylinder, A pinch roller having elasticity by providing a gap opening at at least one end surface between a cylinder and an outer cylinder. 2. The length of the bearing is not more than half the length of the rubber roller in the axial direction.
The pinch roller described. 3. A pinch roller bearing comprising an inner cylinder and an outer cylinder, wherein a gap is provided between the inner cylinder and the outer cylinder at at least one end surface so as to have elasticity. 4. The pinch roller bearing according to claim 3, wherein the inner cylinder and the outer cylinder are connected by an axial and / or radial connecting rib. 5. The pinch roller bearing according to claim 3, wherein the inner cylinder and the outer cylinder are connected by a connecting rib in a radial direction at an end portion, and the gap is opened to the other end surface.