JPS596214B2 - Manufacturing method of tubular body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tubular body used as a single rod body for a fishing rod.

Conventionally, this type of tubular body is made by wrapping a prepreg made of high-strength fiber impregnated with a thermosetting synthetic resin around a mandrel, wrapping cellophane tape around the outer circumference of the prepreg, applying pressure, and then firing it in a firing furnace. It is intended to be manufactured by firing.

By the way, when firing the prepreg wrapped around the mandrel, the temperature of the firing furnace is raised to the curing temperature of the synthetic resin with which the prepreg is impregnated, for example, when using an epoxy resin, the temperature is raised to 140 ° C. The prepreg is fired in a firing furnace for 60 to 90 minutes.

However, in the past, the firing process required a long time, which made continuous work impossible, and when mass producing tubular bodies, the mandrel was used for a long time in the firing process. Because it is necessary to leave the machine idle, a large number of mandrels are required, and the firing process takes a long time, so when mass producing, it is necessary to increase the size of the firing furnace to increase production efficiency. There were problems such as.

Furthermore, since the firing process takes a long time as described above, the amount of energy consumed in this process is extremely large, and when energy problems are being raised, it is necessary to take measures as soon as possible.

Furthermore, when manufacturing a tubular body with a larger diameter and thicker wall,
It takes about 30 to 60 minutes for the mandrel inside the prepreg to reach the set temperature of the firing furnace, and in this case, the firing time naturally becomes longer and energy consumption increases. Because there is a temperature difference between the outer layer and the inner layer during firing, there is a time difference in the curing of both layers, which can cause warping of the manufactured tubular body or variations in strength.

The present invention provides a new method for manufacturing a tubular body in order to solve the above problems all at once.

That is, when the present invention is fired in a firing furnace, the prepreg is heated gradually from the outer layer to the inner layer, and it takes a long time for the inner layer to reach a predetermined temperature, which causes the above-mentioned problems. Before firing in a firing furnace, the mandrel wrapped with the prepreg is heated by induction using a high-frequency electromagnetic induction coil to raise the temperature to near the curing temperature of the synthetic resin, and then fired in a firing furnace. This allows the prepreg to be heated from both the inside and outside. This significantly shortens the firing time in the firing furnace, and since the induction heating time is several tens of seconds to several minutes, even if the induction heating and the firing time are totaled, the time required for the conventional firing process is This significantly shortens the time compared to that, reduces energy consumption, and eliminates warping and variation in strength, making it possible to efficiently and continuously manufacture tubular bodies. The manufacturing method of the present invention will be explained below with reference to embodiments of the drawings. First, as shown in FIG. 1, a tapered mandrel 1 is wrapped with a prepreg 2 made by impregnating high-strength fibers such as glass with a thermosetting synthetic resin, and a cellophane tape or the like is wrapped around the outer circumference of the prepreg 2. A thin tape 3 is wound around the prepreg 2, and the prepreg 2 is pressurized.

Next, the mandrel 1 wrapped with the prepreg 2 is placed in a preheating chamber 5 equipped with a high frequency electromagnetic induction coil 4 as shown in FIG. Raise the temperature to near the curing temperature of the synthetic resin.

For example, when using an epoxy resin as the impregnating resin for the prepreg 2, the mandrel 1 is heated to approximately 140°C. Further, when induction heating is performed using the coil 4, heating is normally performed for 30 seconds each time, but if the number of turns is large or the thickness of the prepreg is large, heating is performed multiple times.

Furthermore, when performing induction heating using the coil 4, the heating chamber 5 may be fixed, and the mandrel 1 may be loaded into the heating chamber 5, left for a certain period of time, and then loaded again, or the heating chamber 5 may be moved. As a formula, this is done by passing it through a mandrel 1 fixed at a fixed position.

After the mandrel 1 is induction heated as described above, it is placed in a firing furnace 6 maintained at the curing temperature of the synthetic resin and fired for 5 to 60 minutes, as shown in FIG. 2B.

When firing in this firing furnace 6, since the mandrel 1 is heated to a predetermined temperature by the coil 4 in advance,
The prepreg 2 wound around the mandrel 1 is heated from the inside by the mandrel 1 and from the outside by the heat of the forming furnace 6. Therefore, the time required to harden the prepreg 2, that is, As mentioned above, the firing time in the firing furnace 6 is significantly shortened, and in other words, the prepreg 2 can be completely cured even in 5 to 60 minutes of firing.

Furthermore, even if the total firing time in the firing furnace 6 and the heating time of the mandrel 1 in the coil 4 are totaled, the required heating time can be reduced by half or less than that in the conventional firing process. Incidentally, the firing in the firing furnace 6 can be carried out continuously by providing a belt conveyor device. After the prepreg 2 is fired and hardened as described above, it is taken out from the firing furnace 6, the tape 3 around the outside is removed, and the surface is finished.
Then, it is made into a tubular body. As explained above, according to the method for manufacturing a tubular body according to the present invention, a high-frequency current is passed through the mandrel using a high-frequency electromagnetic induction coil to preheat the mandrel by induction heating. It is possible to adjust the degree to which the current density concentrates on the surface side, and by changing the high-frequency current value, the temperature rise rate of the mandrel can be adjusted in any way. It is possible to raise the temperature very quickly to a temperature close to the curing temperature of the synthetic resin impregnated in the prepreg wrapped around the mandrel, and the desired amount of heat necessary to sinter the prepreg from the inside, from the surface of the mandrel to a certain inner layer, can be extremely high. Heat can be stored quickly.

Furthermore, when the prepreg wrapped around the rapidly preheated mandrel is placed in the firing furnace and fired, the prepreg is heated from both the inside and outside by the heat radiated from the mandrel and the firing furnace. This makes it possible to significantly shorten the time that the prepreg is heated in the firing furnace compared to the firing process in which the prepreg is heated in the firing furnace. Even if the firing time in the firing furnace and the induction heating time of the mandrel by the induction coil are totaled, the latter heating time is extremely small, so the required heating time can be reduced to more than half compared to the conventional firing process. It is.

Therefore, when manufacturing a tubular body, the manufacturing time of the tubular body can be shortened, and since both the inside and outside of the tubular body are heated, the tubular body is heated with little temperature difference throughout, and a product without deformation can be obtained. Moreover, since the heating capacity of the firing furnace can be reduced, the equipment cost can be reduced, and the heat loss dissipated from the firing furnace is correspondingly reduced. Since the preheated mandrel is wrapped in prepreg, almost all of the heat from the preheated mandrel is supplied to the prepreg, and together with this, there is little overall heat loss and the running cost of manufacturing can be kept low. .

[Brief explanation of the drawing]

The drawings show the manufacturing process of a tubular body according to the present invention, and FIG. 1 is a sectional view showing a state in which prepreg is wound around a mandrel.
FIG. 2 is a diagram showing the firing process of the prepreg. 1...Mandole nore, 2...Prepreg'. 4...High frequency electromagnetic induction Koinore, 6.
・・・・・・Firing furnace.

Claims (1)

[Claims] A prepreg made of high-strength fiber impregnated with a thermosetting synthetic resin is wrapped around a mandrel and fired under pressure and heat.
The manufacturing method involves molding a tubular body, in which a mandrel wrapped with the prepreg is passed through a high-frequency electromagnetic induction coil, the temperature of the mandrel is raised to near the curing temperature of the synthetic resin, and then the mandrel is heated to the curing temperature. A method for manufacturing a tubular body, characterized in that the tubular body is placed in a holding furnace and fired.