JPS5940611B2 - High frequency heating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously high-frequency heating a belt-shaped object to be heated while being conveyed.

Here, as a belt-shaped product, a weather strip 2 embedded in an insert 1 as shown in FIG. 1 will be taken as an example and explained, but the invention is not limited to this.

As shown in FIG. 2, the weather strip 2 is made by coating the insert 1 pulled out from the insert reel 3 with a rubber material by a rubber extruder 4, and then applying it to a high frequency heating device 5.
This causes an eddy current to be generated within the insert 1, and the temperature of the insert 1 is increased due to this resistance loss.

Furthermore, the temperature of the covering rubber is raised by dielectric action using the microwave heating device 6. In this case, the microwave heating device 6 alone does not raise the temperature of the metal insert 1, and the thermal energy generated in the covering rubber is partially consumed in heating the insert 1 through heat transfer, resulting in a decrease in heating efficiency. , and extreme heating, making it difficult to uniformly raise the temperature in a short time. The heated weather strip is kept warm in a hot air heat insulating tank 7 for a required period of time to be vulcanized, taken out by a take-up machine 8, and then bent by a bending machine 9 to be manufactured. At this time, in high-frequency heating when the object to be heated is strip-shaped (flat in cross-section), such as a weather strip insert, a circular (single-turn) heating coil 10 is used, as shown in Figures 1 and 3. It was placed horizontally directly below the object to be heated.

11 is an isoheater core.

Generally, heating efficiency decreases as the conveyance speed of the object to be heated increases, but lowering the conveyance speed is undesirable because it leads to a decrease in production efficiency and an increase in the cost of the product. In addition, in order to improve heating efficiency, a circular heating coil 1 is used.
It is possible to install two or more coils in parallel, but as the heat transfer efficiency decreases in proportion to the cumulative number of coils, a high-frequency heating device with a large capacity is required, which increases equipment costs and
This was disadvantageous in terms of power consumption, etc., and was not practical. In view of the above, an object of the present invention is to provide a high-frequency heating method that can improve heating efficiency in a method of high-frequency heating a belt-shaped object to be heated while being conveyed.

The gist of this invention is that in a method of continuously high-frequency heating a belt-shaped object to be heated while conveying it, the heating coil is twisted into a figure 8 shape, and the figure 8 shape is parallel and horizontal to the conveying direction directly below the object to be heated. This is a high-frequency heating method in which a heating coil is arranged to heat an object to be heated.

The method of this invention will be explained in detail below.

The heating coils 12 used in the method of this invention include the fourth and fifth heating coils.
As shown in the figure, it is twisted into a figure eight shape. The heating coil body is made of a metal with low electrical resistance, such as copper or aluminum, and the inside of the coil is hollow to allow cooling water to pass therethrough to prevent the heating coil itself from generating heat. The surface of the heating coil is electrically insulated by being coated with a synthetic resin or the like to prevent the heating coil from coming into contact with the insert, the human body, or the like and causing a short circuit of the coil. Note that it is desirable to insert an in-heater core 11 into each loop of the heating coil 12 to concentrate the generated magnetic flux density and prevent the heating efficiency from decreasing when the object to be heated is separated from the coil. The heating coil 12 is connected to a high frequency power source via a current transformer (not shown). As shown in FIGS. 4 and 5, the heating coil 12 is arranged so that the figure 8 shape of the heating coil is parallel and horizontal to the conveyance direction directly below the object to be heated (the insert port in the example). The object to be heated 1 is heated.

At this time, the heating coil 12 generates an induced current in each figure-eight loop to the heated object 1 passing over the coil.

These induced currents heat the object without interference. In order to confirm the effects of this invention, each of the heating coils shown in Figs. An experiment was conducted to compare the power input to the coil (frequency 400 KHz) required to heat a coil (width 25 mm x thickness 0.5 mm: made of rolled steel plate) to 200°C. Note that the separation distance of insert 1 from the coil is
The figure shows the distance 5 mm above the coil, and FIG. 5 shows the distance 1 mm above the coil.
Figure 6 shows the results of the experiment, with the solid line A in Figure 5 (Example), the dashed line B in Figure 4 (Example), and the dotted line C in Figure 3 (Example).
These are the results of each method (conventional example). From Figure 7,
It can be seen that the degree of decrease in heating efficiency due to increase in conveyance speed is lower in Examples than in Comparative Examples. Naturally, the embodiment of the present invention (
4 and 5) are longer than the comparison side. In addition, the fourth
In the embodiment shown, the insert 1 is placed on the heating coil 12.
When the power of 0.1 w was applied for 10 seconds, the temperature distribution as shown in Figure 7 (grid hatch: 200
℃, solid line hatch: 150℃, dotted line hatch: 100℃), and the induced current generated from each figure-8 loop is:
It can be seen that the objects to be heated can be heated without mutual interference.

Since the high-frequency heating method of the present invention is the method described above, it is possible to significantly improve the heating efficiency when performing high-frequency heating while conveying a belt-shaped object to be heated, especially when the conveyance speed is high, compared to the conventional method. I can do it.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of a high-frequency heating method for a weather strip, Fig. 2 is a schematic diagram showing the manufacturing process of a weather strip, Fig. 3 is a perspective view of main parts showing an example of a conventional high-frequency heating method, and Fig. 4 The figure is a perspective view of a main part showing one example of the high frequency heating method of the present invention, FIG. 5 is a perspective view of a main part showing another example, and FIG. The graph diagram, FIG. 7, is a temperature distribution diagram of the object to be heated by the high frequency heating method of the present invention. 1...Insert (heated object), 2...
・Weather strip (heated object), 10, 12...
・Heating coil.

Claims (1)

[Claims] 1. In a method of continuously high-frequency heating a belt-shaped object to be heated while conveying it, the heating coil is twisted into a figure 8 shape, and the heating coil is twisted so that the figure 8 shape is directly below the object to be heated, parallel and horizontal to the conveyance direction. A high frequency heating method characterized by heating an object to be heated by arranging a.