JPS5835857B2 - Wankiyoku pipe no Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a curved pipe suitable for application to, for example, a tone arm of a record player, and in particular to a method for producing a curved pipe of good quality using a particularly simple manufacturing device.

An embodiment in which the present invention is applied to a cartridge arm shaft will be described below with reference to the drawings.

First, the material used for the cartridge arm shaft is a fibrous plastic sheet, so-called prepreg sheet.

This prepreg sheet is a composite material of carbon fiber and thermosetting thermoplastic resin such as epoxy resin.

For example, the carbon fiber commercially available under the trade name "Trading Card" has a fiber diameter of 5 to 7μ and a longitudinal elastic modulus of 20,000.
-/can or more, tensile strength 200 kg/IIt1i or more,
It is extremely suitable because it has a density of 1.78 f/cd, which is high strength, high elasticity, and low density.

In this example, several carbon fibers having a volume content of 50 to 55% of the thermosetting resin are used in a laminated manner.

The so-called prepreg sheet 1 laminated in this way
As shown in FIG. 1 (the arrow in the figure indicates the fiber direction), it is wound around the plastic core frame 2 at a predetermined thickness perpendicular to the fiber direction.

When stacking prepreg sheets, when considering rigidity and cracking, as shown in Fig. 2A, prepreg sheets (HaO) with the fiber direction perpendicular to the winding direction should be stacked, for example, at an angle of 45° to the left. The prepreg sheet Nb is made to have a predetermined thickness by sequentially overlapping prepreg sheets 1c tilted at 45° to the right under the prepreg sheet HbO.

Also, if only the elastic modulus is considered, as shown in Figure 2B,
It can also be constructed of only the prepreg sheet (1a) whose fiber direction is perpendicular to the winding direction (thin lines in FIGS. 2A and B indicate the direction of the carbon fibers).

Further, the above-mentioned flexible core frame 2 is preferably made of a heat-resistant material, such as synthetic rubber or fluororesin.

When winding the prepreg sheet 1 around the horizontal bar 2, an adhesive can be applied to the prepreg sheet to facilitate winding.

This so-called prepreg sheet which is wound and superimposed is the third
It is molded into a cartridge arm shaft using a heat press molding device as shown in the figure.

This mold device for heat press will be explained with reference to FIG. Upper molds 5 and 6 of the mold are arranged, and heaters 7a for heating the cylindrical prepreg sheet are provided in the upper mold 5 and the lower mold 6, respectively.

7b is placed.

As shown in FIG. 4, the lower mold 6 has an arm shaft female mold 8 having a lower half cross section of the arm shaft for the cartridge to be molded.
A guide pin 9 for inserting the mold is installed on the surface in contact with the upper mold 5, and the female mold 8 is a so-called J-shaped arm shaft female mold with one end slightly bent.

Therefore, the upper mold 5 also has a structure similar to the lower mold 6.

That is, the upper mold 5 has a female mold having an upper half section of the cartridge arm shaft and a through hole into which the guide pin 9 of the lower mold 6 is inserted.

Next, to explain the manufacturing process of the cartridge arm shaft, the above-mentioned cylindrical prepreg sheet is sandwiched between the heat press mold configured as above.

The volume content of the prepreg sheet is as described above, but in order to increase the volume content after molding, prevent voids, and improve strength, the volume content of the prepreg sheet may be greater than the 14° 150 cross-sectional area of the upper and lower molds. desirable.

The cylindrical prepreg sheet set in place is
It is fixed by lower molds 5 and 6, and is heated by a heater 7a.

7b presses the upper and lower molds 5 and 6.

In this example, a pressure of 10 kg/c4 is applied to a cylindrical prepreg sheet having the above volume content, and the pressure is maintained for about 30 minutes in an atmosphere at a temperature of about 170°C.

However, the horizontal bar punching fixed to the upper and lower molds 5 and 6,
The mold is released, and the epoxy resin is cut and shaped to form a cartridge arm shaft (see FIG. 5).

In this case, in order to make the material of the thermoformed arm shaft appropriate, it is best to anneal the molded arm shaft for about 2 hours before cutting and shaping to obtain better performance in terms of deformation characteristics over time. .

As described above, according to the present invention, a fibrous plastic sheet is wound and laminated around a horizontal bar made of a flexible material using a simple manufacturing device, that is, a heat press mold device mainly having upper and lower split molds. Since the above-mentioned horizontal bar was removed during hot compression molding, the Young's modulus of thermosetting resin such as epoxy becomes a very small value due to heat, and it is difficult to use flexible materials. Since both ends of the horizontal bar are free, the horizontal bar expands in the longitudinal direction due to heat expansion, making it very easy to pull out the horizontal bar.

The core material itself becomes more elastic as the temperature rises, making it easier to pull out, and since it is pulled out while still in the mold, the material is less likely to lose its shape during molding.
As a result, the surface and back surfaces of the curved pipe have a good finish, making it possible to obtain a high-quality curved pipe.
Various curved pipes (for example, straight pipes, J-shapes, S-shapes, etc.)
shape, etc.).

Therefore, according to the arm shaft for a cartridge used in a record player using the present invention, not only can the above-mentioned effects be obtained, but also because of the so-called prepreg sheet, the cross-sectional area of the arm shaft can be compared with that of a conventional arm shaft made of an aluminum pipe. Even when the same amount is used, the rigidity is significantly greater and the equivalent mass is smaller than that of a conventional arm shaft made of an aluminum pipe.

Conventionally, in the manufacturing method of this type of curved pipe, especially arm shafts, a fibrous plastic sheet is wound around a rigid horizontal bar, the surface of which is further wrapped with cellophane tape, etc., and the core frame is simply heated with a heater. However, according to the present invention, it is difficult to pull out the horizontal bar, and unnecessary stress is applied to the pipe, causing it to warp. Such inconveniences can be avoided, and since the horizontal bars are removed during hot compression molding, it is possible to obtain a curved pipe with good finishing on the front and back surfaces.

FIG. 6 shows another example of the arm shaft obtained by the present invention, and this example is a so-called S-shaped arm shaft that takes into account the imbalance in the lateral direction.

Therefore, by molding this S-shaped female mold into a heat press mold, an S-shaped arm shaft can be obtained.

Therefore, it goes without saying that the above-mentioned effects can also be obtained in this example.

Note that the synthetic resin does not have to be epoxy resin; phenolic resin or polyester resin can also be used, and the shape of carbon fiber is only an example.Although the present invention has only been described with respect to an arm shaft for a tone arm, the spirit thereof can be understood. Various configurations can be adopted within the range, and the scope of application is to apply to curved pipes in general.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted perspective view showing a state in which a prepreg sheet is wound around a plastic horizontal bar, Fig. 2 is a schematic perspective view for explaining the prepreg sheet, and Fig. 3 is an example for carrying out the present invention. FIG. 4 is a perspective view showing an example of the lower die, and FIGS. 5 and 6 are perspective views showing examples of the arm shaft. 1 is a prepreg sheet, 2 is a flexible core frame, 5 is an upper mold,
6 is a lower mold, 7a and 7b are heaters, and 8 is an arm shaft female mold.

Claims (1)

[Claims] 1 A composite material sheet made of carbon fiber and thermosetting or thermoplastic resin is wound and laminated around a horizontal bar made of a flexible material, and the horizontal bar is placed in a mold with both ends free and heated. A method for manufacturing a curved pipe, comprising compression molding, removing the horizontal bar during the molding process, and then releasing the laminate from the mold to form a curved pipe.