JPS6053364B2 - Head shell and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a head shell to which a cartridge constituting a pickup of a record player is attached, and which is made of a composite material of organic substances such as vinyl chloride, petroleum pitch, and lignin and solid powder. The present invention relates to a head shell having low density and high elasticity.

Traditionally, what has been desired for the head shell of a record player is that it has high rigidity and does not cause split vibration, and that the density of the material is low in order to reduce the equivalent mass of the stylus tip, and that it is easy to mold and process as a product. A uniform and structurally robust finish is required.

By the way, aluminum, titanium, magnesium, carbon fiber, etc. have been used as conventional head shell materials.

Among these, aluminum, titanium, and magnesium have a small specific modulus of elasticity, making it difficult to manufacture a light and highly rigid head shell. For this reason, when a combination of large-scale needles with large needle tip compliance is used, the low-frequency resonant frequency becomes too low, picking up low-frequency noise caused by warping or eccentricity of the record, which often worsens the S/N ratio. Katta. Furthermore, since aluminum and titanium have low internal loss, they tend to cause resonance due to the force exerted on the stylus tip from the record during record playback, which often seriously impairs sound quality. On the other hand, it is difficult to form carbon fiber units into the J-shape of the head shell, and some kind of binding material is required.

In this case, polymeric material (synthetic resin) is generally used as the binder.
By using carbon fiber, a composite material of carbon fiber and polymer material is formed, but overall the specific modulus of elasticity decreases and it is not possible to exhibit the high elasticity characteristic of carbon fiber itself. . In view of these points, an object of the present invention is to provide a head shell made of a composite material of an organic substance and solid powder that is lightweight and has high rigidity at an extremely low cost.

That is, the present invention is constructed from a composite material of an organic material such as vinyl chloride, petroleum pitch, lignin, etc. and solid powder, and obtains a head shell having the above-mentioned characteristics by oxidizing the organic material of the composite material.

In the present invention, organic substances include thermosetting and thermoplastic synthetic resins, petroleum pitch, coal tar pitch, tetrabenzophenazine, lignin, etc., and solid powders include ceramic powder, It is an inorganic powder such as glass powder or carbon powder (carbon black, graphite powder), and does not melt at temperatures below 500°C.

The present invention will be explained below with reference to the drawings, using vinyl chloride (PVC) as an organic substance and graphite powder (scaly graphite) as an example of a solid powder.

Kneading process (composite material production) PVC is heated (400° C.) in a non-oxidizing atmosphere such as nitrogen or argon gas to obtain a pitch-like material.

There are also other ways to obtain pitched PVC, such as PVC
It is also possible to use a plasticizer or a solvent. PV
Adding graphite powder with a particle size of 0.1 to 50 μm to C pitch,
Knead with a kneader or roller while heating to 200-300°C.

To facilitate kneading, a solvent is used to turn the PVC pitch into a liquid having an appropriate viscosity at room temperature, and the pitch is kneaded without heating. The amount of graphite powder (solid powder) added is 10~
It will be in the range of 90 Wt%, but 30 to 7? % gives good results.

In general, the smaller the particle size of graphite powder (solid powder), the better, and preferably 0.1 to several μm or less. Molding process The composite material, in which PVC pitch and graphite powder are kneaded, then enters a molding process.

In this molding step, the material that has undergone the above-mentioned kneading step is molded into the desired shape of the head shell. It should be noted here that the shape formed in this molding step preferably has all the shapes that will eventually become the head shell. That is, the molding is done taking into consideration the cartridge attachment hole, lead wire attachment hole, etc. in the head shell.
The mixture is heated and kneaded into two press molds that are shaped into the desired shape and size to become the head shell.
It is heated to about 00 to 300°C and press-molded.

It is kneaded with a solvent, then press-molded at room temperature, and thoroughly dried to remove the solvent. In the case of a powder mixture, the powder is compression molded. In this case, heating the mold to about 300'C increases the strength of the molded product and makes it easier to handle in subsequent steps. In addition, in the molding process, before molding the kneaded composite material into the shape of the head shell,
By extruding the composite material into a plate shape and then molding it using the above-described pressing method, the graphite powder is oriented, which is extremely effective in improving the elastic modulus and mechanical strength.

The molded product obtained in the molding step, which is a pre-oxidation step, is heated to 250 to 30 CfC in air (in an oxidizing atmosphere) to oxidize at least the surface of the molded product.

The temperature in this oxidation step is 500°C or less, 100'C
The heating rate is preferably 1 to 20 C/hour.

Note that this oxidation may be carried out in ozone at a temperature of about 50 to 80°C for 4 to 8 hours, and then further carried out at the above-mentioned temperature.

In addition, since the molded product may be deformed by heating in the oxidation step, a wire mesh or a punched thin metal plate may be placed on a jig formed into the shape of a head shell, or may be clamped.

Further, good results can be obtained by setting the heating time to 1 m or more.

The present invention has been described in detail above, and examples of the present invention will be described below.

30 to 70 wt % of flaky graphite with a particle size of several μm and 70 to 9 wt % of pitch-shaped vinyl chloride (PVC) are kneaded while heating, and this is press-molded into the shape of a head shell. The molded product is heated to 300°C in an oxidizing atmosphere at a sufficiently slow temperature increase rate.

Through this heat treatment process, hydrogen chloride is released from the vinyl chloride and the matrix is made infusible (oxidized).

The head shell thus obtained has a density of 1.3 to 2.
．． 0y/Cltl Young's modulus 3000k9/i~9000
It has a characteristic of k9/i.

The present invention has a relatively high specific elastic modulus, a larger internal loss than metals such as AlTi, excellent heat resistance, and low temperature processing in an oxidizing atmosphere, resulting in extremely low manufacturing costs. have an effect.

[Brief explanation of the drawing]

The figure is a process diagram showing the manufacturing method of the present invention.

Claims (1)

[Scope of Claims] 1. A head shell made of a composite material of an organic substance such as vinyl chloride, petroleum pitch, lignin, and solid powder, and formed into a shape to be a head shell, in which the organic substance covers at least the surface of the head shell. A head shell characterized by being oxidized. 2. Knead organic substances such as vinyl chloride, petroleum pitch, and lignin with solid powder that does not melt at temperatures below 500°C and form it into the shape that will become the head shell.
A method for manufacturing a head shell, comprising oxidizing the molded product at a temperature of 500° C. or lower in an oxidizing atmosphere.