JPS60234149A - Fly wheel for tape recorder - Google Patents

Abstract

PURPOSE:To raise the strength of the weld between a capstan shaft and a fly wheel, so as to decrease the thickness of the welded part and miniaturize the fly wheel, by welding the capstan shaft to the fly wheel by beam welding. CONSTITUTION:A belt winding rim 12 made of plastics, is formed on the outer circumference of a sheet disk 11, which is formed of such as a cold rolled steel plate. A stepped part 14a at the lower end of a shaft 14, whose surface is hardened by a heat-treatment, by such as case hardening, is inserted in the center of the disk 11, and the shaft 14 and the disk 11 are welded with each other, by welding three points by spot welding 15, such as laser welding or electron beam welding. As the capstan shaft 14 and the disk 11 are welded with each other strongly, the strength of the weld is not reduced, the shaft 14 is kept being square with the disk 11, and it is not feared that the disk 11 falls out, if the thickness of the welded part is decreased.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a tape recorder in which the rotational speed of a capstan is kept constant and even, in order to stabilize the running speed of the tape and reduce wow and flutter. This invention relates to a flywheel for a tape recorder.

[Technical background of the invention and its problems] As shown in FIG. 7, in the flywheel of a conventional tape recorder, a bushing 2 is press-fitted into a capstan shaft 1.
into the shaft hole 3a of the flywheel 3 made of brass, iron, resin aluminum, zinc die-casting, etc., or insert the capstan shaft 1 into the shaft hole 3a of the flywheel 3 as shown in FIG.
There is one in which the fitting part is joined with an adhesive.

Alternatively, a stepped portion 1a may be formed on the capstan shaft as shown in FIG. 9, and the lower end of the capstan shaft 1 may be caulked on the lower surface of the flywheel 3, or may be welded as shown in FIG. 10.

However, in the case of FIGS. 7 to 9, in order to maintain the surface angle of the capstan shaft 1 and flywheel 3 and maintain the strength of the joint, the joint thickness must be increased. Therefore, there was a tendency for the weight of the center portion, which has no influence on the flywheel effect, to increase.

Further, in the case of FIGS. 9 and 10, the caulking and welding portions protrude from the lower surface of the flywheel 3, so that the tape recorder has been made thinner in order to accommodate the dimensions thereof.

On the other hand, in the case of in-vehicle tape recorders and portable tape recorders installed in automobiles, etc., vibration is applied, and this vibration is transmitted to the flywheel, which is also affected by it, and the total weight of the flywheel is large. As the flywheel effect is maintained, the rotational moment cannot be changed.

Also, if it is to be carried around, it must be particularly lightweight, so
The amount of wasteful M must be reduced as much as possible.

[Purpose of the invention]

In order to eliminate the above-mentioned drawbacks of the conventional method, the present invention performs beam welding such as laser welding or electron beam welding on the flywheel and capstan shaft, thereby eliminating the need to increase the thickness of the joint as in the conventional method. The object of the present invention is to provide a flywheel for a tape recorder, which has a reduced weight without changing the rotational moment and is optimal for use in a vehicle or for carrying.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

11 is a disk made of cold-rolled steel plate or the like, and has a plastic rim 12 on its outer periphery for winding a belt, and when used as a flywheel that also drives a reel, a reel stand and a reel stand near its inner periphery. A meshing reel drive section 13 is formed.

To form the rim 12 and the reel drive part 13 on the disc 11, the disc 11 with a small hole 11a for coupling with the reel drive part 13 is placed in a predetermined injection mold, and plastic is shot. This is based on the so-called outsert method.

For this reason, the gates 12a and 13a are provided at equal intervals on the rim 12 and the reel drive unit 13 because the gates 12a and 13a are thin near the gates. Therefore, the gates 12a and 13a are arranged so that the weight of the gates 12a and 13a is balanced as a whole.

The step part 14a at the lower end of the shaft 14, which has been subjected to surface hardening heat treatment such as carburizing and quenching, is inserted into this disc 11, and spot welding 15 such as laser welding or electron beam welding is performed to join the disc 11 and shaft 14 at three locations. It is something to do.

In the above embodiments, the rim 12 is formed of a plastic outsert, but the outer periphery of the disk 11 may be formed of an annular bent portion 11b as shown in FIG.

Furthermore, the surface angle and fitting position between the shaft 14 and the disc 11 are determined by the stepped portion 14a of the shaft 14, but by using a jig it is also possible to form a straight shaft as shown in Fig. 5+al. .

Furthermore, beam welding is performed by moving the beam in a circular manner outside the spot welding 15 to perform annular welding as shown in FIGS.
(BL end face welding etc. can also be used.

〔Effect of the invention〕

As mentioned above, the present invention employs beam welding such as laser welding or electron beam welding, so even if the capstan shaft is made of hardened steel such as carburized or high carbon steel, the overall temperature is low. It is possible to maintain the quenched hardness without increasing the hardness, prevent wear of the capstan shaft, and prevent bending, deformation, etc., resulting in a high yield.

Since the capstan shaft and the thin disc are firmly welded, the joint strength is greater than conventional press-fitting or adhesive bonding, and even if the joint thickness is reduced, the surface angle between the capstan shaft and the disc is is maintained, and there is no risk of the disk slipping out.

Furthermore, it is possible to reduce wow and flagging caused by vibrations from the outside, and it is possible to obtain a flywheel that has good followability with respect to control of the drive motor.

Moreover, unlike conventional caulking or welding, there is no part that protrudes from the underside of the flywheel, so it is necessary to take this dimension into consideration, which can contribute to thinning.

As described above, the present invention is most suitable as a flywheel for an in-vehicle tape recorder, which places emphasis on vibration resistance, or a portable tape recorder, which requires light weight, miniaturization, and vibration resistance.

[Brief explanation of drawings]

Figures 1 and 2 are a back view and an enlarged cross-sectional view of essential parts of one embodiment of the present invention, Figure 3 is a central longitudinal cross-sectional view of Figure 1, and Figure 4 is a longitudinal cross-section of another embodiment of the rim. 5(al) and (b) are longitudinal sectional views and back views of other embodiments with different shaft shapes, and FIG.
Figures fa) and (b) are longitudinal cross-sectional views and back views of other embodiments, and Figures 7 to 10 are vertical cross-sectional views of conventional flywheels. 11... yen ffi, 12... rim, 1
4...Shaft, 15...Beam? g
Contact. Patent Applicant Pioneer Co., Ltd. Agent Hideo Takino Figure 1\-~ノ'', 50 Figure 9 370-

Claims (1)

[Claims] A capstan shirt 1- made of hardened iron material is fitted into the center hole of a thin plate-like disk made of iron material with a rim around which the belt is wound, and the fitted part is laser welded and electronically welded. A flywheel for a Cheeble kneader that is characterized by beam welding such as beam welding.