JPS6031004B2 - arm pipe - Google Patents

Description

[Detailed description of the invention] The present invention relates to an arm pipe for a cord player.

In order to improve the tracing ability of the cartridge, it is desirable to reduce the mass of the vibration system and increase internal loss to prevent split vibration.

In order to reduce the mass of the vibration system, it is possible to make the arm pipe and head shell lighter, but if the wall thickness is made thinner in order to reduce the weight, the rigidity will decrease, making unnecessary split vibrations more likely to occur and deteriorating the thermal quality. This will result in For this reason, arm pipes and head shells made of highly rigid and lightweight materials, that is, materials with high specific elastic modulus and large internal loss, are desired. However, conventionally used arm pipes and head shells made of metal materials such as aluminum, titanium, and beryllium have a high specific modulus of elasticity, but have low internal loss and are not suitable for technical applications.

Arm pipes and head shells made of carbon fiber are also known, and have excellent physical properties in that they have a high specific modulus of elasticity and a relatively large internal loss. However, in the case of carbon fiber, it is necessary to combine it with synthetic resin in order to mold it into arm pipes and head shells.
There is a problem in that the overall specific modulus of elasticity decreases due to the combination with this resin. Furthermore, recently, the inventors have proposed arm pipes and head shells made of a mixture of polyvinyl chloride and flaky graphite powder. This material has a specific modulus of elasticity comparable to that of a metal material, and an internal loss that is one order of magnitude higher than that of a metal material. However, it was still insufficient in terms of internal loss. The present invention has been made in view of such conventional problems, and its purpose is to provide an arm pipe that is lightweight, highly rigid, has a high specific modulus of elasticity, and has a high internal loss.

That is, the present invention provides an arm pipe obtained by molding a thickened material of a thermoplastic resin and flaky graphite powder, which the present inventors have proposed, by adding, for example, polyvinyl chloride to the thermoplastic resin. The present invention provides an arm pipe characterized by using a plurality of types of polyvinylidene chloride, including those whose glass transition points are higher than room temperature and those whose glass transition points are lower than that.

In general, polymeric materials have the property that when the temperature reaches the glass transition point, the elastic modulus decreases, while the internal loss rapidly increases.

Therefore, in an arm pipe made of a material that is a mixture of a polymer material with a glass transition point higher than room temperature and a polymer material with a glass transition point lower than that, it is possible to freely control internal loss by adjusting the blending ratio of the materials. can. Furthermore, in order to improve the elastic modulus of the arm pipe, it is possible to mix flaky inorganic powder such as flaky graphite powder into the material, and to orient the powder along the surface of the molded product when forming the arm pipe. . The present invention has been made with attention to this point, and will be explained in detail below.

Examples of thermoplastic resins that have a glass transition point higher than room temperature include polyvinyl chloride (PVC), a copolymer of this PVC and polypynylacetate, and a copolymer of PVC and polyacrylonitrile. Polyvinylidene chloride (PVDC) has a glass transition point lower than room temperature.
A copolymer of PVDC and PVC, a polymer of PVDC and polyacrylonitrile, etc. are used. The flaky graphite powder preferably has an average particle size of about 20 m or less, especially 5 m.
Those with a diameter of m or less are suitable. In addition, if the blending ratio of graphite powder and thermoplastic resin is in the range of 10 to 9 t% graphite powder and 90 to 1 t% resin, it is expected that the graphite powder will improve the elastic modulus, and the molding of the kneaded material Graphite powder 50
-75M%, and when the resin content is 50-25M%, the properties of the molded product are significantly improved. When manufacturing arm pipes,
First, resin 1 and graphite powder 2 are kneaded while being heated to a temperature at which the resin softens using a kneader or rolls, as shown in FIG. 1a.

Add plasticizers and stabilizers if necessary. In the case of kneading with rolls, the kneaded material 3 is obtained as a rolled sheet material, and the graphite powder 2 is oriented parallel to the sheet surface as shown in FIG. 1b, and the material before molding is The elastic modulus itself is high. Next, this kneaded material 3 is
Form into the desired shape of arm pipe A as shown in the figure. For this forming, two sheets of material 3 are used as shown in Figure 3a.
are placed on both sides of the core 4, and then, as shown in FIG.
A method of cutting out the core 4, or a method of rolling the sheet material 3 into a cylindrical shape and bonding the seam 7 with thermocompression or adhesive as shown in FIG. 4 is used. According to these methods, the graphite powder 2 is oriented along the surface of the arm pipe A, as shown in FIG. 5, and has a high elastic modulus. To further improve the properties of the arm pipe, carbonization or graphitization treatment is applied.

For this purpose, the arm pipe obtained by the above method is put into a predetermined mold and kept in shape, first subjected to a preliminary treatment to make it infusible, and then removed from the mold and placed in a non-oxidizing atmosphere or in a vacuum. In this method, a method is used in which the material is heated to a carbonization temperature of about 120 p<0> or graphitization temperature of about 2500[deg.] C. at a rate of 10 to 2 p<0>/hr and then fired. The infusibility treatment is performed by heating the material in an oxidizing atmosphere for 1 to 30 minutes.
This is carried out by heating and firing while gradually increasing the temperature to about 35° C. at a rate of 10° C./hr. The present invention will now be explained in detail based on examples.

Figure 6 shows the blending ratio of resin and graphite powder at 1:2 (weight ratio).
and the combination of resins is a copolymer of PVC and polyvinyl acetate as a material with a high glass transition point, and a copolymer of PVDC and poly-IJ acrylonitrile as a material with a low glass transition point. It shows how the elastic modulus and internal loss of the arm pipe formed after roll rolling changed when the composition ratio was changed between
The plasticizer (BP8G) was added at a ratio of about 1/IQ stabilizer (lead stearate) to the resin at about 1/50 of the resin.
As can be seen from the figure, the elastic modulus E indicated by the dotted line is PVDC
It does not change much even if the compounding ratio of is increased, but on the other hand, the internal loss tan6 shown by the solid line increases dramatically as the PVDC increases.

Further, the density p of this arm pipe is approximately 1.84 m/earth. Now, when the physical property values are compared with those of other materials when the blending ratio of PVDC is 3 T% and PVC is 7K%, the following table shows the results. In addition, this arm pipe is held in a mold and heated at 1 to 10°C up to about 300qC in an oxidizing atmosphere.
/hr to make it infusible by heating, and then in a non-oxidizing atmosphere to about 120,000 1
The characteristics of the arm pipe obtained by heating and carbonizing at a temperature increase rate of 0 to 20° C./h are shown in the same table. In addition, the properties of the arm pipe obtained by graphitizing the carbonized arm pipe by raising the temperature to about 250° C. are also shown in the same table. As is clear from the table above, according to the examples of the present invention, high elasticity can be achieved through the addition and orientation of graphite powder, and high internal loss can be achieved due to the presence of a material with a low glass transition point in the resin. Moreover, since each constituent material is light, lightweight can also be achieved.

In other words, it is possible to achieve a specific elastic modulus comparable to or higher than that of titanium or aluminum metals, and it is also possible to achieve a value of one tone or more in terms of internal loss. Furthermore, if carbonization treatment is applied, the elastic modulus will be approximately 80%, and graphitization treatment will increase the elastic modulus to approximately 2. It improves needle sound, approaches beryllium in specific elastic modulus, and has an internal loss of 1M tones or higher than that of metals. According to the present invention, as described above, it is possible to provide an arm pipe that is lightweight, has high rigidity, has a large specific modulus of elasticity, and has a large internal loss.

Further, according to the present invention, since the materials are thermoplastic resin and graphite powder, it can be manufactured at low cost and at the same time is extremely easy to mold.Moreover, the properties can be freely controlled by adjusting the material composition, and the properties can be achieved at low cost. We can provide a good arm pipe. Brief description of the drawings: Figures 1a and 1b are explanatory diagrams showing the manufacturing process of the sheet-like mixed twill material used in the present invention, Figure 2 is a partially cutaway front view of one embodiment of the present invention, and Figure 3 Figures a and b are explanatory diagrams showing one example of the method for manufacturing the arm pipe of the present invention, Figure 4 is an explanatory diagram showing another example of the same manufacturing method as above, and Figure 5 is an explanatory diagram showing an example of the arm pipe of the present invention. The front sectional view and FIG. 6 are characteristic change diagrams of the embodiment of the present invention.

1... Thermoplastic resin, 2... Graphite powder, 3... Mixed twill material, A... Arm pipe.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. An arm pipe formed of a kneaded material mainly composed of a thermoplastic resin and flaky graphite powder so that the graphite powder is oriented along the surface, the arm pipe having glass added to the thermoplastic resin. An arm pipe characterized by the use of multiple types of pipes, one with a transition point higher than room temperature and the other with a transition point lower than normal temperature. 2. The arm pipe according to claim 1, wherein the thermoplastic resin contains polyvinyl chloride and polyvinylidene chloride as main components. 3. Claims 1 or 2, characterized in that the thermoplastic resin kneading material is carbonized or graphitized.
The arm pipe described in section.