JPH0583976B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pinch roller device used in magnetic tape devices such as tape recorders and VTRs.

BACKGROUND ART As is well known, in a magnetic tape device, a pinch roller presses a magnetic tape against a capstan, and the cooperative action of the two allows the magnetic tape to be transferred at a predetermined speed. Conventional devices of this kind generally have the pinch roller bearing section supported on the pinch roller shaft without eccentricity, so if the capstan shaft and the pinch roller shaft are not parallel, the outer circumferential surface of the pinch roller may not align with the capstan shaft. This resulted in the tape not being crimped and causing poor tape running.

For this reason, as shown in, for example, Utility Model Publication No. 40-14430, Utility Model Publication No. 43-19241, Utility Model Publication No. 43-23381, Utility Model Publication No. 48-36656, Utility Model Publication No. 49-4882, etc. Various types of self-aligning pinch roller devices have been devised, but all of them have almost the same structure as the self-aligning type bearings conventionally used in general machinery and equipment, and are complicated in structure and do not use ball bearings or the like. This made it expensive and not suitable for mass production.

Utility Model Publication No. 48-24245 and Japanese Patent Publication No. 47-36402 disclose means for solving such problems, but the problems described below remain and it has been difficult to put them into practical use.

FIG. 2 is an explanatory diagram showing how the pinch roller device described in Japanese Utility Model Publication No. 48-24245 is used. Elastic theory 1 rotatably loosely fitted to the pinch roller shaft 11
An annular groove 13 is formed on the upper and lower surfaces of the pinch roller shaft 11 concentrically with the pinch roller shaft 11 so that the outer ring portion 14 can be easily bent, so that the capstan shaft 15 and the pinch roller shaft 11 are parallel to each other. Even without this, the outer ring portion 14 aligns with the capstan shaft 15 and makes uniform contact as shown.

FIG. 3 is a sectional view of the pinch roller structure described in Japanese Patent Publication No. 47-36402. Instead of the conventional rubber roller, it is a one-piece construction made of a plastic material whose outer ring portion 16 is thin enough to be bendable and which is continuous with the central hub portion 17 by a disk portion 18. Since the outer ring portion 16 is flexible, even if the capstan axis and the pinch roller axis are not parallel, the outer ring portion 16 follows the capstan axis and makes uniform contact.

Problems to be Solved by the Invention However, with the above configuration,
As stated in Japanese Patent No. 24245, problems such as eccentricity of the pinch roller cannot be solved.
That is, since the pinch roller is a one-piece structure made of an elastic material such as rubber, the groove bottom is easily bent in the radial direction, and when the pinch roller is pressed against the capstan shaft, the pinch roller is deformed and loses its circular shape.
On the other hand, there was a contradiction in that if the groove bottom was made sufficiently strong, the desired bending due to the groove bottom could not be obtained.

Furthermore, since the bending rigidity is generally smaller than the compressive rigidity, even if it is desired to polish the outer periphery to improve the roundness of the outer ring portion 14, the vicinity of the end surface reinforcement will bend, making the machining difficult. There is also the problem that it is not possible. Furthermore, since the effective elastic modulus of the pinch roller is naturally different between the part with the groove bottom and the part without it, there is also the fundamental problem that the magnetic tape cannot be pressed onto the capstan shaft with a uniform force.

Also in the configuration described in Japanese Patent Publication No. 47-36402, as stated in the same publication, the disc portion 18
Since the pinch roller provides strong support in the radial direction, the effective elastic modulus of the pinch roller is naturally different between the portion where the disk portion 18 is present and the portion where it is not, and the magnetic tape cannot be pressed onto the capstan shaft with a uniform force. Moreover, since the magnetic tape is crimped onto the capstan shaft using only the bending of the outer ring portion 16, variations in the thickness of the outer ring portion 16 cause variations in the bonding pressure, making it impossible to obtain a stable pressure bond. There are also problems.

In view of the above-mentioned problems, the present invention provides a pinch roller device with a simple structure that allows the pinch roller to stably contact the capstan shaft with uniform pressing force even if the capstan shaft and the pinch roller shaft are not parallel. It is.

Means for Solving the Problems In order to solve the above problems, the pinch roller device of the present invention has a pinch roller shaft, a pinch roller shaft that is rotatably loosely fitted to the pinch roller shaft, and has upper and lower surfaces concentric with the pinch roller shaft. a cylindrical member that forms a pair of annular grooves and connects an outer circumferential portion and an inner circumferential portion with flexibility at the center; and an elastic member that fits concentrically with the outer circumferential portion, the cylindrical member The thickness of the outer circumference in the radial direction is sufficiently larger than the thickness of the flexible part of the pinch roller in the axial direction, so that the flexible part is more easily bent.

Effect: With the above-described configuration, the present invention absorbs the non-parallelism between the pinch roller axis and the capstan axis by self-centering bending of the flexible part of the cylindrical member, so that the elastic theory is always uniformly distributed on the capstan axis. The elastic coefficient is the same at every point on the outer periphery because it is in contact with the cylindrical member and is fitted concentrically with the cylindrical member, and is supported by the rigidity of the cylindrical member, resulting in a uniform crimp force. It will be.

Embodiment A pinch roller device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of a pinch roller device according to an embodiment of the present invention. In FIG. 1, a pair of annular grooves 4 and 5 are formed on the upper and lower end surfaces of the pinch roller shaft 1 so that a flexible portion 3 is formed approximately at the center of the cylindrical member 2 that is rotatably loosely fitted onto the pinch roller shaft 1. It is formed concentrically. Of course cylindrical member 2
The outer peripheral portion 7 of the roller is also arranged to be concentric with the pinch roller shaft 1. When the elastic material 6 made of rubber or the like is fitted onto the outer peripheral portion 7 of the cylindrical member 2, the outer peripheral surface of the elastic material 6 is naturally concentric with the pinch roller shaft 1. A tapered portion is formed on the outer peripheral portion 7 so that the elastic material 6 can be easily fitted therein.

Further, the thickness of the outer circumferential portion 7 is larger than that of the flexible portion 3, so that the flexible portion 3 bends more when a radial force is applied.

In addition, the upper and lower end surfaces of the inner circumferential portion 9 of the cylindrical member 2 are made slightly lower than the upper and lower surfaces of the outer circumferential portion 7 to prevent axial force from being applied to the flexible portion 3 when fitting the elastic member 6. There is. The cylindrical member 2 can be made of polyacetal resin, nylon resin, fluorine resin, etc.
Rotational friction with the pinch roller shaft 1 can be reduced, and the flexible portion 3 can easily be bent. The flexible portion 3 is provided with a constricted portion 8 on the inner side so that the self-aligning action of the outer peripheral portion 7 of the cylindrical member 2 can be effectively obtained.

As described above, according to the present embodiment, a pinch roller shaft and a pair of annular grooves that are rotatably loosely fitted to the pinch roller shaft and are formed concentrically with the pinch roller shaft on the upper and lower surfaces of the outer peripheral portion of the pinch roller shaft are provided. and a cylindrical member whose inner periphery is connected by a central flexible part, and an elastic member that fits concentrically with the outer periphery, and the thickness of the outer periphery is greater than the thickness of the flexible part of the cylindrical member. The structure is made so that the flexible part is easier to bend, so even if the capstan axis and the pinch roller axis are non-parallel, the flexible part 3 of the cylindrical member 2 bends, so that the elasticity 6 is aligned with the capstan axis. There will be even contact.

Since the elasticity theory 6 is supported by the rigidity of the outer periphery 7 of the cylindrical member 2, the elastic modulus is almost uniform at every point on the outer periphery, and the magnetic tape can be crimped onto the capstan shaft with uniform force.

In the above embodiment, the cylindrical member 2 is loosely fitted directly onto the pinch roller shaft 1, but it may of course be loosely fitted through various bearing materials. Moreover, the cylindrical member 2
It is clear that the material is not limited to those mentioned above.

The same effect can also be obtained by forming the cylindrical member in one piece, but by forming the inner circumferential part 9 and the outer circumferential part 7 separately and assembling them so that the substantially central part is connected by a flexible member or the like. it is obvious. Furthermore, the shape of the bottom of the annular groove is not limited to that shown in the drawings.

Effects of the Invention As described above, the present invention has a pinch roller shaft, and a pair of annular grooves that are rotatably loosely fitted to the pinch roller shaft and formed concentrically with the pinch roller shaft on the upper and lower surfaces of the outer circumference. a cylindrical member whose inner periphery is connected by a flexible central portion, and an elastic member that fits concentrically with the outer periphery, and the thickness of the flexible portion of the cylindrical member in the axial direction of the pinch roller is By making the radial thickness of the outer peripheral part sufficiently large and configuring the flexible part to bend more easily, even if the capstan shaft and the pinch roller shaft are non-parallel, the cylindrical member can be easily attached to the approximately central part of the cylindrical member. The provided flexible portion bends and plays a self-centering role, so that the elastic force uniformly contacts the capstan shaft.
Furthermore, since the elastic tape is fixed concentrically to a relatively rigid cylindrical member, it has approximately the same elastic modulus at any point on the outer periphery, and a uniform tape pressing force can be obtained.

Furthermore, after polishing the outer peripheral surface of the elastic theory,
Since it is assembled by fitting into a cylindrical member, a pinch roller device with high roundness accuracy can be obtained with a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a pinch roller device according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views of a conventional pinch roller device. 2...Cylindrical member, 3...Flexible part, 6...Elasticity, 7...Outer peripheral part.

Claims (1)

[Claims] 1. A pinch roller shaft, which is rotatably loosely fitted into the pinch roller shaft, and has a pair of annular grooves concentrically with the pinch roller shaft formed on the upper and lower surfaces, so that the outer peripheral part and the inner peripheral part are flexible at the center. The flexible portion of the cylindrical member has a cylindrical member connected at a portion thereof, and an elastic member that is concentrically fitted to the outer periphery, and the thickness in the radial direction of the outer periphery is sufficiently greater than the thickness of the flexible portion of the cylindrical member in the axial direction of the pinch roller. The flexible portion is more flexible than the outer peripheral portion, so that when the elastic ring receives uneven force in the axial direction, the cylindrical member forms an inclination with the pinch roller axis. pinch roller device.