JPH026517Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to a pinch roller that pinches a magnetic tape between a capstan that is driven to rotate forcibly in a tape recorder, VTR, etc., and controls the transfer of the magnetic tape.

(General technical issues) Pinch rollers must have the ability to rotate as smoothly as possible, but it is also essential that they have an automatic centering function to ensure stable tape running. be. In other words, if the centering function is not provided or is insufficient, the transfer tape may be biased or elongated due to errors in the parallelism of the axes of the capstan and pinch roller, which are unavoidable due to design and manufacturing. In severe cases, the tape may come off the pinch roller, or the tape may fluctuate up and down or the running speed may fluctuate, increasing the amount of wow and flutter.

(Prior art) The most common structure of conventional pinch rollers is a cylindrical sleeve with an elastic tire such as rubber fixed to the outer circumferential surface, which is rotatably supported on the roller shaft via a ball bearing. . However, in this case, the ball bearings mentioned above must be extremely precise and compact, which not only increases the manufacturing cost of the pinch rollers, but also generally reduces the smoothness of rotation due to uneven precision of the anti-friction balls. It was difficult to obtain sufficient satisfaction. In addition, the above-mentioned ball bearings attempt to achieve the desired self-aligning effect by utilizing the clearance between the anti-friction balls and the inner and outer rings of the bearing, which would otherwise cause harmful rattling. Because of this, the amount of automatic alignment was small, and the alignment function was not smooth.

As one means to solve these problems, recently, a spherical part centered on the axis of the roller shaft has been formed on the inner peripheral surface of the metal sleeve, as shown in Japanese Patent Application Laid-Open No. 155559/1983. On the other hand, a spherical surface corresponding to the above is formed on the lower outer peripheral surface of the bearing metal made of a sintered oil-impregnated alloy that is rotatably and slidably fitted to the roller shaft, and a self-aligning effect is achieved by sliding contact between both spherical surfaces. A pinch roller has been proposed to achieve this. However, such conventional technology requires the installation of a coil spring or the like that elastically restrains the bearing metal from above in order to hold it in a predetermined position. Not only does this cause some problems in the stable tape transfer function, but also the direct sliding contact between the spherical parts of the bearing metal and the sleeve causes rotational support and automatic displacement. Because the alignment is performed, the sliding contact surface is subject to severe wear, causing harmful rattling relatively early, and the friction noise caused by the sliding contact causes wow, wow, etc.
There were problems such as flutter, which adversely affected audio characteristics.

(Purpose of the invention) The purpose of this invention is to solve all the various problems of the prior art as described above. In other words, both the rotary support and self-alignment functions can be made extremely smooth, without adversely affecting audio characteristics such as wow and flutter, increasing the service life, and improving the control range of self-alignment. It is an object of the present invention to provide a structure of a pinch roller that can have a large size, and can also be manufactured easily including processing and assembling the members, thereby achieving a reduction in manufacturing costs.

(Structure and Embodiments) The structure of this invention will be described below based on illustrated embodiments.

Reference numeral 1 denotes a roller shaft, and 2 a short cylindrical bearing fitted in an intermediate portion in the longitudinal direction of the roller shaft, which is supported on an annular flange 1a integrally formed on the outer circumferential surface of the roller shaft 1. In addition, this bearing 2 has an outer peripheral surface that is similar to the roller shaft 1.
It is formed in a spherical part 2a with the center O on the axis l of. Of course, this spherical surface portion 2a only needs to be formed on at least both the upper and lower portions of the outer circumferential surface, and the intermediate portion thereof may be formed on a vertical surface 2b parallel to the axis l, as shown by the chain line in FIG. Also good.

3 is a cylindrical metal sleeve, 4 is a cylindrical elastic body made of synthetic rubber or the like fixed to the outer peripheral surface of the sleeve, and 5 is a cylindrical bearing holder that is tightly fitted and fixed in the sleeve 3; An annular groove 6 having a substantially trapezoidal cross section is formed on the inner circumferential surface, into which the outer circumferential surface of the bearing 2 is loosely fitted, forming a sleeve 3 with the center O as a fixed point, as shown in FIG. The predetermined angle θ
It is assumed that tilting permission (self-aligning behavior) is allowed within the range of .

By the way, the bearing 2 and bearing holder 5 are as follows:
Both of them are composed of permanent magnets, and as shown in FIG. 2, their mutually different polarities are located at the close opposing parts, that is, the upper and lower parts where the spherical part 2a and the inner surface of the annular groove 6 are close to each other. Each pair of N and S poles is magnetized so as to constitute two closed magnetic circuits C facing each other. And both of these 2,
A magnetic fluid 7 for lubrication is interposed between the closely opposing surfaces of the spherical portion 2a of 5 and the inner surface of the annular groove 6 to be attracted and held by the above-mentioned magnetic force.

As the magnet body used for the bearing 2 and the bearing holder 5, alnico magnets, ferrite magnets, resin magnets, etc. can be exemplified, but resin magnets are particularly preferably used because of moldability, ease of manufacture,
This is the most advantageous in terms of mass production. This resin magnet is made by kneading ferromagnetic powder and thermoplastic or thermosetting resin, molding it, and magnetizing it at the required locations.
(Fe ₂ O ₃ ) ferrite represented by n [where M is one or more of Ba, Pb, Sr, Ca, and Co, m and n are positive integers], or the general formula RCo ₅ or R ₂ Co ₁₇ [wherein R is one or more of Sm, Y, Ld and Co], and the resins include polyamide resin, polyethylene resin, Thermoplastic materials such as polyethylene terephthalate resin, or thermosetting materials such as epoxy resin, unsaturated polyester resin, and phenol formaldehyde resin are used. The blending ratio of the ferromagnetic powder and synthetic resin, other molding conditions, etc. are in accordance with conventionally known methods.

Further, the magnetic fluid 7 is composed of magnetic particles dispersed in oil via a surfactant, and functions as a lubricant.

The bearing holder 5 is divided into upper and lower parts, with the horizontal plane where the center O of the spherical part 2a of the bearing 2 is located as a dividing plane.
Divided upper holder 5a and lower holder 5b
It is composed of a combination of By configuring the bearing holder 5 into two parts in this way, during assembly production, the lower holder 5b is fitted and fixed in the sleeve 3 in advance, and then the roller shaft 1 with the bearing 2 mounted thereon is fitted into the sleeve 3 from above. Then, by fitting the upper holder 5a into the sleeve 3, the pinch roller can be easily assembled. In addition, in the figure, 8 is a washer, and 9 is an E-ring that holds it in place.

(Operation and Effect) Since this invention has the above-described configuration, the cylindrical elastic body 4, the sleeve 3, and the bearing holder 5 are integrated around the bearing 2 fitted to the roller shaft 1. While rotating, the spherical portion 2a of the outer peripheral surface of the bearing 2 is fitted into the corresponding annular groove 6 of the bearing holder 5 in a state that allows relative tilting behavior, thereby forming a kind of spherical universal joint. As a result, the self-aligning action of freely tilting and displacing the outer circumferential surface of the roller in the axial direction within a predetermined angular range can be realized over a relatively large control range. Moreover, the bearing 2 and the bearing holder 5 are
Both of them are composed of magnets, and a magnetic fluid 7 that is attracted and held by the magnetic force of the magnet is interposed between their close opposing surfaces, so that the rotation and alignment effects are achieved by the lubricating action of the magnetic fluid 7. Not only can this be done smoothly, but also their wear can be significantly reduced. And, the magnetic fluid is applied to the bearing 2 and the bearing holder 5.
The closed magnetic circuit C, which has different polarities facing each other, is used to attract and hold the magnetically attracted parts, so that the holding action is reliable, and there is no possibility of fluid leakage. Coupled with the fact that it is possible to keep a small amount of liquid at the effective working area at all times, it is possible to maintain good rotational performance and self-aligning performance over a long period of time, greatly improving durability, and preventing rattling etc. There is also less risk of adverse effects on audio characteristics such as wow and flutter. Furthermore, the number of component parts is small, manufacturing is simple, and the cost of parts is lower than when using expensive ball bearings, so it can be manufactured and provided at low cost.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; FIG. 1 is a longitudinal sectional view, and FIG. 2 is an enlarged sectional view of the main parts. 1...Roller shaft, 2...Bearing, 2a...Spherical surface,
3... Sleeve, 4... Cylindrical elastic body, 5... Bearing holder, 5a... Upper holder, 5b... Lower holder, 6... Annular groove, 7... Magnetic fluid,
C...Closed magnetic circuit.

Claims (1)

[Claims for Utility Model Registration] (1) On the outer peripheral surface of the roller shaft 1, at least both the upper and lower parts of the outer peripheral surface are centered O on the axis l of the roller shaft 1.
A short cylindrical bearing 2 formed on a spherical part 2a is fitted therein, while a cylindrical bearing holder 5 is tightly fitted into a sleeve 3 having a cylindrical elastic body 4 fixed to its outer circumferential surface. The outer circumferential surface portion of the bearing 2 including the spherical surface portion 2a is loosely fitted into the annular groove 6 formed on the circumferential surface, thereby allowing the sleeve 3 to tilt within a predetermined angular range; Both the bearing 2 and the bearing holder 5 are formed of magnets that are magnetized so that different poles face each other to form a closed magnetic circuit, and the spherical portion 2a of both of them faces each other. A pinch roller in which a lubricating magnetic fluid 7, which is attracted and held by the magnetic force of the magnet body, is interposed between the inner surface of the annular groove 6 and the inner surface of the annular groove 6. (2) The pinch roller according to claim 1, in which the bearing 2 and the bearing holder 5 are both made of resin magnets. (3) The bearing holder 5 consists of an upper holder 5a and a lower holder 5b which are divided into upper and lower halves with the horizontal plane where the center O of the spherical portion 2a exists as a dividing plane. Pinch roller mentioned.