JP2944422B2 - Heating device for thermoplastic resin sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus for a thermoplastic resin sheet.

[0002]

2. Description of the Related Art Conventionally, as a heating device for heating a thermoplastic resin sheet before molding, heaters having various shapes using electricity as a heat source have been used.
A typical example is a far-infrared heater in which an electric heating coil is coated with ceramic and fired, and these heaters are used at regular intervals on the upper and lower surfaces of a sheet to be heated. The heater temperature is controlled or the zone is divided to control the heater temperature for each zone.

[0003] The basic function required of the above-mentioned heating device is that the sheet to be heated can be uniformly heated over the entire surface. Therefore, in order to eliminate uneven heating due to various external factors, temperature control for the heater as described above has been performed. Therefore, the conventional heating device requires a large amount of electric heating cost, requires high equipment for control, and is complicated in management.

Therefore, in recent years, a catalytic combustion gas heater has been developed with the aim of reducing energy costs, facilitating equipment installation, and increasing heating efficiency, and has developed a high infrared heating effect and energy consumption by using combustion gas. Due to cost savings, it has come to be used as a heating furnace for thermoplastic resin sheets.

[0005]

However, in a heating furnace using a catalytic combustion gas heater, in order to control the heater surface temperature in detail, it is necessary to individually control the gas flow rate.
The accuracy, equipment and cost were all inferior to the electric heater. If a constant amount of air is not always supplied to the combustion section on the gas heater surface, the combustion temperature will drop. And, in the case of a heating furnace having a form close to a closed state, the oxygen-deficient state is apt to occur, and the heating of the sheet becomes unstable. For the above reasons, as long as a gas heater with a relatively large surface area is used, the temperature cannot be lowered only in the central part according to the degree of drawdown of the sheet at the time of heating. Overheating was not achieved, and uniform sheet heating was not possible.

Accordingly, it is an object of the present invention to stabilize the heater temperature and to provide uniform heating by inclining the heater according to the drawdown of the heating sheet.

[0007]

According to a first aspect of the present invention, there is provided a heating device for a thermoplastic resin sheet according to the present invention which can achieve the above-mentioned object, by utilizing catalytic combustion heat of a combustible gas as a heating element of the heating device. And a gas heater having a predetermined inclination angle with respect to the surface of the sheet to be heated.

The arrangement of the gas heater is divided into two parts at a position corresponding to the center of the sheet, and the center of the sheet to be heated is symmetrically distant from the left and right ends of the sheet toward the center. It is characterized in that each is provided to be inclined at a predetermined angle so as to leave. Further, as a venting means for the gas heater, a venting means capable of forcibly sucking air is provided in the heating device to assist the catalytic combustion of the heater.

Further, the inclination angle of the gas heater is set so that the inclination angle of the heater disposed in the heating device can be changed according to the degree of slack of the heated object sheet during heating. It is characterized by being done.

[0010]

According to the present invention having the above-described structure, the sheet to be heated is heated by the planar gas heater utilizing the catalytic combustion heat of the combustible gas. Since it is arranged with a predetermined inclination angle with respect to one surface of the lower surface, it is possible to perform heating corresponding to the drawdown of the sheet to be heated accompanying the heating, and to realize uniform heating.

In particular, the arrangement of the gas heater is divided into two parts at a position corresponding to the center of the sheet, and the gas heater is positioned symmetrically farther from the left and right ends of the sheet to be heated toward the center. When each is inclined at a predetermined angle, the rise of heat and the flow of air are improved, and in particular, if the ventilation means capable of forcibly sucking air from the back of the heater is provided, the heat Ascent and airflow will be further enhanced.

It is more convenient if the inclination angle of the heater is not fixed but is variable so that it can be changed according to the degree of slack (drawdown) during heating of the sheet to be heated. .

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a heating apparatus for a thermoplastic resin sheet which is continuous with a forming section. Reference numeral 1 denotes a heating furnace for a molding machine serving as a heating apparatus of the present invention, and 2 denotes a catalytic combustion gas heater provided in a heating furnace 1. In addition, it is a planar type utilizing the catalytic combustion heat of combustible gas. FIG. 1 shows a case when viewed from the front, and can be arranged at a predetermined inclination angle with respect to the upper and lower surfaces of the sheet S to be heated (see FIG. 2).

Further, the heater 2 is provided with a sheet S to be heated.
Are divided in two at a position corresponding to the center of the sheet S, and each is inclined at a predetermined angle so as to move away from the sheet S to be heated symmetrically from the left and right ends toward the center. Reference numeral 3 denotes a blower, which serves as a ventilation means capable of forcibly sucking air from the back surface of the heater 2 on a central symmetry axis of the heater 2 symmetrically arranged in the heating furnace 1.

Reference numeral 4 denotes a guide for adjusting the angle of the heater 2 which is rotatably connected to the pivot 20 by a part thereof. In the drawing, a cylinder mechanism is illustrated, but it is implemented by a vertical adjustment mechanism such as a chain. You can also. The angle adjustment guide 4 is more convenient if it is provided in communication with a slack detection sensor so that the inclination angle of the heater can be automatically changed according to the degree of slack during heating of the sheet S to be heated. Makes it easier to manage.

Reference numeral 5 denotes a supply section for a sheet S to be heated by a thermoplastic resin sheet, for example, a composite sheet with a foamed sheet or a non-foamed film of polystyrene, polypropylene, polyethylene, or polyethylene terephthalate, or a non-foamed sheet. , 7 are a press device, 8 is a press cylinder mechanism by hydraulic pressure or the like, and 9 is a molding die.

The heating furnace 1 was designed to be completely open as shown in FIG. 3 in order to easily take in air. However, the sheet S to be heated is very easily affected by the outside air temperature. Therefore, in the present invention, the heating furnace 1 is sealed as shown in FIG. 2 so that air can be introduced from a partial location (not shown), and air can be forcibly sucked from the suction port 30 by the blower 3. Thus, the flow of air that assists combustion on the surface of the heater 2 can be improved.

In the drawing, S 'represents a slack drawdown state of the sheet S to be heated. In addition, as a heater, L
A combustion type planar heater that generates NG or LPG by a flameless catalytic reaction and efficiently generates long-wave infrared rays is used. Next, a specific example of the sheet S to be heated will be described with data. Specific example 1. Used heater Catalytic combustion gas heater (manufactured by Cataritec, USA) Size 12 inch x 36 inch (upper and lower two) Used gas Propane gas Operating pressure 152 m / m Aq Heater surface temperature (performance value) 430 ° C Heating the material PP foam sheet thickness 2.3mm weight 500g / m ² 3. Molded product φ170m / m (Diameter) 36m / m (Depth) Round plate 4. 4. Heating time 12-15 seconds Evaluation

[0019]

[Table 1]

In the case of Experiment 1 in which the heater was not provided with an inclination angle, the occurrence of a thinning phenomenon of a molded article due to overheating was observed. The heater temperature is a value measured by an infrared radiation thermometer. From the above specific examples, it has been found that the heating state is improved by heating at least the upper and lower heaters while inclining and suctioning the air with respect to at least the heated object sheet, and the sheet forming state after the heating is also improved. .

[0021]

As described above, according to the present invention, a planar gas heater utilizing catalytic combustion heat of a combustible gas is heated so as to have a predetermined angle with respect to the surface of a sheet to be heated. As a result, air can be easily taken in, uniform heating can be achieved in response to the drawdown of the sheet, and fuel consumption can be saved as compared with a heat source using electric power.

When a ventilation means capable of forcibly sucking air is provided, the heater temperature can be further stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a heating device of the present invention used in a molding line.

FIG. 2 is a sectional view of a main part.

FIG. 3 is a sectional view showing an example of an open heating furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Heater 20 Pivot part 3 Ventilation means by blower 30 Suction port 4 Angle adjustment guide

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B29B 13/00-13/10 B29C 35/00-35/18

Claims (4)

(57) [Claims] 1. A heating device having a planar gas heater utilizing catalytic combustion heat of a combustible gas as a heating element, wherein the gas heater has a predetermined inclination angle with respect to a surface of a sheet to be heated. A heating device for a thermoplastic resin sheet, wherein 2. The arrangement of the gas heater is divided into two parts at a position corresponding to the center of the sheet, and each of the gas heaters is set at a predetermined angle so as to be symmetrically distant from the left and right ends toward the center from the left and right ends. The heating device for a thermoplastic resin sheet according to claim 1, wherein the heating device is provided to be inclined. 3. The heating apparatus for a thermoplastic resin sheet according to claim 1, wherein ventilation means capable of forcibly sucking air is provided in the heating apparatus so as to assist catalytic combustion of the heater. 4. The apparatus according to claim 1, wherein the inclination angle of the heater disposed in the heating device is changed so as to be able to change in accordance with the degree of slack of the sheet to be heated during heating.
Or a heating device for the thermoplastic resin sheet according to 2.