KR900004745B1 - The method of manufacturing of rotating head drum - Google Patents

Abstract

The head drum for VTR or DAT comprises an upper and an lower drum of which outer material is circular pipe made of aluminium alloy. After forming the circular body with the pipe material, the enginnering plastic like BMC (bulk mold compound) is insertmoulded or outer- moulded to form the drum body. The outer surface is cut with a certain inclined degree to form the tape lead line.

Description

Manufacturing Method of Plastic Rotating Head Drum Outer of Aluminum Alloy Pipe

1 is a partially cutaway front view showing a configuration of a head drum in general.

Figure 2a, b is a longitudinal cross-sectional view and bottom view of the upper drum of the present invention.

3 is a partially cutaway front view of the hard rum of the present invention.

* Explanation of symbols for main parts of the drawings

11: outside the drum drum 12: outside the hard drum

11a, 12a: Cutting groove 12b: Lead line

13,14: upper and lower body 15,16: upper and lower body

The present invention relates to a head drum used in a video cassette recorder (hereinafter referred to as "V-al") or a digital audio tape recorder (hereinafter referred to as "diety"). It relates to a method of manufacturing a plastic rotating head drum formed of a pipe of the inner diameter portion of the outer diameter portion with a high dimensionally stable material to enable the production of upper and lower drums at a low cost in a simple process.

In VRC or DAT employing a rotating head drum, the head drum is used to perform a function of reading or recording a recorded signal from a tape, and is an expensive part that is processed and assembled with high precision.

The general structure of the head drum is as shown in FIG. 1, the rotary shaft 5 supported by the upper and lower bearings 3 and 4 is assembled at the center of the lower drum 2, and the lower part of the rotary shaft 5 is assembled. The rotor 6 of the motor is attached to the rotary shaft 5 to rotate by the magnetic field of the stator 7 of the motor fixed to the lower part of the lower drum 1, and the upper side of the rotary shaft 5 The upper drum 1 is attached to the flange 8 fixed to the rotating shaft 8 so as to rotate together with the rotation shaft 5.

In addition, two to five video heads 9 are mounted on the lower side of the upper drum 1 so as to protrude slightly from the outer circumferential surface of the upper drum 1, and tapes are attached to the outer circumferential surface of the lower drum 2. An inclined lead line 10 for inclining is formed, and the video head 9 scans at a constant speed on the magnetic layer of the tape wound around the upper and lower drums 1 and 2 along the lead line 10. It is designed to record or reproduce signals.

The upper and lower drums (1) and (2) are forged with aluminum alloy material (for example, A2218, AHS, etc.), and then processed by lathes, such as rough machining, drilling, threading, milling, buffing, and precision lathe machining. , Through a variety of machining processes, such as precision lead line processing, each is assembled in the state shown in FIG.

However, such conventional head drum processing requires enormous equipment investment, and the processing process is complicated and precise, and the defect rate is high and it takes a lot of time. There was a problem that was inhibited.

The object of the present invention is to change the structure of the rotating head drum to form the area where the tape actually contact is made of aluminum alloy and the inside of the injection molding using engineering plastics having high dimensional safety, the productivity is significantly improved and the cost is remarkably improved. The purpose is to provide a lower drum, upper and lower.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2 and FIG. 3, in the rotary head drum used for BC or DI, the outer diameter portion 11 of the drum in which a metal such as an aluminum alloy is drawn in a circular pipe, and the tape is directly in contact with the tape. And after forming the lower drum outer diameter part 12, the upper and lower drum outer diameter parts 11 and 12 are normally mounted in an injection molding machine, and then insert molding is made of a material having high dimensional stability such as a bulk mold compound (BMC). The upper and lower drum bodies 13 and 14 fixed to the rotating shaft by molding or outsert molding are molded into a single body.

At this time, the upper and lower drum bodies (13) and (14) are formed at the position where the fixing hole for fastening the fixing screw, the signal line drawing hole, and the various functional holes are designed, and the upper and the outer diameter parts of the aluminum alloy pipe (11) (12) between the upper and lower drum bodies (13) and (14), which are internal molds, for relatively high shrinkage of the axial marks at the time of drawing, the grooves (11a) (12a) at the time of cutting and the aluminum alloy. By the strong bonding force is applied to the upper and lower drum outer diameter portion (11, 12), the upper and lower drum body (13, 14) is firmly coupled.

The upper drum 15 is milled by several video head windows 15a, and the lead line 12b is brought into contact with the tape on the surface of the outer diameter portion 12 of the hard drum 16 at a predetermined inclination. ) Is cut once and then finished to finish the upper and lower drums (15, 16).

The screw portions provided in the upper and lower drums 15 and 16 may be self-tapping or may be separately added.

In addition, the BMC is a thermosetting resin (0.1% or less) whose shrinkage is close to zero (0% or less), which has very high dimensional stability and a good surface state of the molded article. In order to apply the MBC to the present invention, a small amount of carbon is mixed in order to prevent an electrostatic discharge and used in a state in which some conductivity is imparted.

As described above, the present invention forms the outer diameters of upper and lower drums with metal pipes such as aluminum alloys, and the upper and lower drum bodies are molded by inserting the outer and lower drum outer diameter parts with high dimensional safety materials and inserts or outer inserts. After the upper and lower drums are formed, the upper and lower drums are completed by a simple process of processing the video head window on the upper drum and forming a tape leadline on the hard drum. Significant savings in capital equipment investment, which has been required, can reduce manufacturing costs, improve productivity, and contribute to the weight reduction of products.

Claims (2)

In the rotary head drum used for the V-CRT or the diet, the upper drum outer diameter part 11 and the hard drum outer diameter part 12 to which the tape is directly contacted and run are formed of a metal round pipe, and the upper and lower drum outer diameter parts 11 are formed. 12) is a BMC or a high dimensional stability insert or the outer insert molding the upper and lower drum body (13, 14) fixed to the rotating shaft to the aluminum alloy pipe, characterized in that composed of a single body How to make a loose plastic rotating head drum. The body (13) (14) according to claim 1, wherein the outer diameter portions (11) and (12) are made of aluminum alloy pipes, and the body (13) and (14) formed with drawing marks and cutting grooves (11a) (12a) are formed on the inner circumferential surface thereof. And a screw portion of the body (13) (14) is self-tapping at the time of injection molding.

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