JPS5819706A - Turntable for recording carrier and its production - Google Patents

Abstract

PURPOSE:To produce a turntable with high working efficiency, by using an Mg alloy or Mg as a material and arraying radially the forging lines toward the outer circumference from the center part. CONSTITUTION:A hot forging material of an Mg alloy or Mg is used to produce a turntable. A material billet is first put at the center upper part of a preheated forging mold 1. Then the billet is pressed by a punch 3 of a press forming machine and then extended into an even concentric circle to form a center flat part 4 and a thick fringe part 5. Then the punch 3 is pulled up and a molded product 6 is pulled out of the punch 3 by means of a mold releasing ring 7. Thus a forging process is through. Such product 6 undergoes a heat treatment and a mechanical working to be formed into a desired turntable. This table has highly stable rotations owing to the dense metallic crystal particles with no cavity and an even weight to the center of rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a turntable (
(hereinafter abbreviated as turntable) and its manufacturing method.

Conventional turntables are generally press-formed from steel plates or aluminum plates, or die-cast from aluminum alloys or zinc alloys.

Although the press forming method is excellent in mass production, it is known that product precision is reduced due to variations in the rolling direction characteristics of the rolled plate, variations in material plate thickness, and residual strain caused by pressure forming.

In particular, the characteristics in the rolling direction are inconvenient for rotating disk-shaped objects such as turntables. Further, in order to further improve the quality and accuracy of the turntable produced by this processing method, inefficient secondary machining that requires skill is required.

Furthermore, in the die-casting method, there is a difference in the timing of shrinkage as the molten metal cools and solidifies, causing deviations in the internal composition due to distortion, and the formation of thin cavities. As a result, the weight balance of the turntable becomes uneven, requiring time and effort to adjust the balance.

The present invention aims to eliminate the drawbacks of the conventional turntable as shown in the following paragraphs, and to provide a method for manufacturing a turntable with high working efficiency.

The material used for the turntable of the present invention is a magnesium alloy or a magnesium hot forging material.

Next, an embodiment of the manufacturing method of the present invention will be described with reference to the drawings. FIGS. 1 to 4 are cross-sectional views of an apparatus showing the manufacturing process. First, a material billet (2 ) was heated to 400°C to give it plasticity, and then placed in a press molding machine (1000°C) as shown in Figure 2.
Position the punch (3) of t) in the second part, pressurize the raw billet 2) with the punch (3) as shown in Figure 3, stretch the billet (2) uniformly and concentrically, and finally The central flat part (4) and peripheral thick part (5) of the turntable are formed by backward extrusion, and finally the punch (3) is raised by 1" and tightened to the punch (3) for shrinkage due to temperature drop. Place the turntable molded product (6) on the release ring (7).
) was used to escape from the punch (3) and complete the forging process, or the forging process of this example was completed in just 1 minute and 30 seconds.

Note that the forging temperature is not limited to the above, but may range from 200 to
Any temperature within the range of 510°C can be selected.

Further, in FIG. 1, it is preferable that the crystal grains of the material billet (2) placed on the forging die (1) extend downward.

The turntable molded product (6) can be made with T according to the application.
5 and T6 heat treatment or after natural cooling, the outer, inner, and upper and lower surfaces are finished by cutting, and a hole (8) for inserting the rotating shaft is drilled in the center to produce a finished product as shown in Figs. 5 and 6. It is finished as shown in Figure 6.

If it is necessary to increase the moment of inertia, the thickness and height of the inside (5) of the peripheral edge thickness may be increased as appropriate.

The turntable formed as shown above is finished by forging, so that the flow lines are arranged radially from the center to the outer periphery, and the metal crystal particles are densely structured. Since there are no defects such as blowholes and the weight is uniform with respect to the center of rotation, the conductivity of the acoustic frequency is uniform and the rotation is stabilized.

On the other hand, since magnesium or magnesium alloy is used as the material, it has excellent damping ability (vibration absorption ability) and can absorb vibrations from the outside and the turntable drive unit.
For example, when used in a player, it has an excellent property of suppressing unnecessary vibrations, that is, wow and flutter, to the cartridge.

In addition, the manufacturing method enables molding to be performed in an extremely short time compared to conventional turntables made by casting, etc., and the grain flow lines are arranged radially from the center to the outer periphery. This has the effect of making it possible to efficiently produce turntables having the following characteristics.

It should be noted that the above-mentioned turntable is not limited to one for use in record players, and of course includes turntables for use in various types of record carriers.

[Brief explanation of the drawing]

1 to 4 are central sectional views of an apparatus showing a manufacturing process for explaining a method for manufacturing a turntable for a record carrier according to the present invention, and FIG. FIG. 6 is a sectional view of the center of the embodiment shown in FIG. 5. In the diagram (1)...Forging die, (2)...Billet, (3
)...Punch, (4)...Central flat part, (5)...
- Surrounding thick wall part, (6)...molded product, (7)...release ring, (8)...hole. Patent applicant: Wasi Kosan Co., Ltd., Figure 1, Figure 2

Claims (1)

[Claims] 1. A turntable for a record carrier, characterized in that the material is a magnesium alloy or magnesium, and the grain flow lines are arranged radially from the center to the outer periphery. 2. For a record carrier, which is characterized by heating a magnesium alloy or a magnesium hot forging material to make it plastic, placing it on a forging die, and press-forming it using a backward pushing method. How to manufacture a turntable.