JPH06196255A - Manufacture of sheathed heater - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the quality of a heating plate by simplifying the shape of the heating plate of an electric cooking device. CONSTITUTION:A heater 6 is inserted into a pipe 5, magnesia is filled in it, the pipe 5 is machined into a noncircular pipe 8 having a flat section 8a, the flat section 8a is brought into contact with the outer bottom face of a heating plate 1, the heater 6 is excited to heat the pipe 8, then excitation is stopped, and the pipe 8 is pressed to the heating plate 1 for pressure connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sheathed heater for heating a heating plate which is attached to a heating plate of an electric cooker such as a hot plate or an electric rice cooker.

[0002]

2. Description of the Related Art In an electric cooker, a heater is attached to the inside of the outer casing of the electric cooker, a heater separate type for heating by placing a heating plate on the heater, and a heater on the outer bottom surface of the heating plate. There is a heater built-in type which is internally provided and places a heating plate on an exterior body for heating. In the latter heater built-in type, two holding protrusions 2 as shown by a chain line in FIG. 7 are provided on the outer bottom surface of the heating plate 1, and the heater 3 covered between the two holding protrusions 2 is provided. After the insertion, the holding projection 2 is bent inward and the covered heater 3 is swaged (see the solid line in FIG. 7). The shape of the covered heater 3 in the longitudinal direction is formed in a substantially ring shape in order to uniformly heat the entire surface of the heating plate 1 (see FIG. 8), and both ends thereof are connected to the connection terminals 4.

[0003]

Since the outer bottom surface of the heating plate 1 must be provided with two projections 2 for holding, the shape of the mold for molding the heating plate 1 becomes complicated, and the mold can be manufactured. There is a problem that it becomes difficult, and the heating plate made of aluminum cast in a mold with a complicated shape has a problem that shrinkage cavities and cracks easily occur and the quality of the heating plate easily deteriorates. Since small irregularities are likely to occur on the upper surface of the plate, there is a problem that the upper surface of the heating plate has to be corrected and processed when the fluororesin coating is performed. Therefore, the manufacturing cost of the heating plate 1 becomes expensive.

When the outer bottom surface of the heating plate 1 is made flat and the two holding projections 2 are welded, insufficient welding is likely to occur, which is a cause of corrosion. When the protrusion 2 is brazed, the strength of the welded portion is insufficient. An object of the present invention is to solve such a problem, and to provide a manufacturing method in which a heater 3 covered with a heating plate 1 having a simple shape is pressed.

[0005]

In order to achieve the above object, in the method for manufacturing a sheathed heater of the present invention, a heater is inserted into an aluminum pipe, and a magnesia is provided in a gap between the heater and the pipe. After filling, while processing the cross-sectional shape of the pipe into a non-circular shape having a plane portion,
Bending processing into a substantially ring shape that can heat the heating plate evenly,
Next, the flat portion of the pipe is brought into contact with the outer bottom surface of the aluminum heating plate, and the heater is energized to 200 to 56 degrees.
After heating to 0 degree, the energization is stopped, the pipe is pressurized, the pipe is compressed and deformed, and the pipe is pressed against the heating plate.

Alternatively, a heater is inserted into an aluminum pipe, the gap between the heater and the pipe is filled with magnesia, and then the pipe is drawn into a small diameter pipe to increase the density of the magnesia inside. Together with, processing the cross-sectional shape of the pipe into a non-circular shape having a flat surface portion,
Bending processing into a substantially ring shape that can heat the heating plate evenly,
Next, the flat portion is brought into contact with an aluminum heating plate, and the heater is energized to heat it to 200 to 560 degrees, and then the energization is stopped, and the pipe is pressurized to press the outer bottom surface of the heating plate. .

Alternatively, a coated heater having a heater inserted in a pipe and magnesia filled in a gap between the heater and the pipe is formed into a non-circular outer peripheral surface having a flat surface portion and an inner peripheral surface having a shape. Is inserted into an aluminum heater holder having a circular shape, and then the heater holder is bent into a substantially ring shape capable of uniformly heating a heating plate, and a flat portion of the heater holder is formed. To the outer bottom surface of the heating plate, energize the heater to heat it to 200 to 560 degrees, and then stop energizing, pressurize the heater holder to compressively deform it and press-contact the outer bottom surface of the heating plate. .

Alternatively, a flat surface portion is formed on one side and 2 on the other side.
A heater holder made of aluminum having a cross-sectional shape in which a projection for holding a strip is formed is bent into a substantially ring shape capable of uniformly heating a heating plate, and the heater is inserted into a pipe. A coated heater in which a gap between the pipes is filled with magnesia is bent into the same shape as the heater holder and is inserted between the two holding protrusions, and the tip of the holding protrusion is bent toward the coated heater. In addition to performing the caulking process, the heater is energized to heat the heater to 200 to 560 degrees to stop energization, and the flat portion of the heater holder is pressed against the outer bottom surface of the heating plate to press the outer bottom surface of the heating plate. Press against.

[0009]

[Function] A coated heater in which a heater is inserted inside an aluminum pipe and filled with magnesia is compressed and deformed when the cross-sectional shape is processed into a non-circular shape having a flat surface portion,
Although the density of the magnesia becomes high, when it is pressed against the heating plate, it is compressed and deformed again, and the density of the magnesia becomes higher. Energize the heater to turn the coated heater 200 degrees to 560
Since the power supply is stopped and the heating plate is pressed against the heating plate after being heated, it is possible to prevent the risk of electric leakage during the pressing.

When the aluminum pipe or heater holder is heated to 200 ° to 560 °, the aluminum pipe or heater holder becomes flexible and easily joined, and is pressed against the aluminum heating plate with compression deformation. To be done. Since the flat portion of the coated heater or the heater holder is pressed against the heating plate, the amount of the coated heater biting into the heating plate is reduced and the amount of deformation of the heating plate is reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. FIGS. 1A to 1D are schematic views showing a manufacturing method of a first embodiment of the present invention. As shown in FIG. The heater 6 is inserted into the aluminum pipe 5, and both ends 6a of the heater 6 are projected from both ends of the pipe 5. Next, the magnesia 7 as an insulating material is filled between the pipe 5 and the heater 6 (see FIG. 1B) to form a covered heater.

Next, the pipe 5 is pressed by a press to process the cross-sectional shape of the pipe 5 into a non-circular pipe 8 having a plane portion 8a (see FIG. 1C). This pipe 8
Since the pipe 5 is compressed and deformed, the density of the magnesia 7 inside is increased. Next, in order to uniformly heat the entire surface of the heating plate 1, the shape of the pipe 8 in the longitudinal direction is bent into a ring shape with an open mouth, as shown in FIG.

Next, the flat portion 8a is brought into contact with the outer bottom surface of the aluminum heating plate 1, and the heater 6 is energized to make the pipe 8
After heating to 200 to 560 degrees Celsius, the energization is stopped, the pipe 8 is pressed to deform the pipe 8 by compression, and is pressed against the heating plate 1 (see FIG. 5). The energization is stopped in order to prevent the occurrence of electric leakage during pressurization, and for example, a sensor that detects that a pressing member (not shown) that pressurizes the pipe 8 starts moving toward the pipe 8 ( Energization is stopped by a signal (not shown).

The flat portion 8a is pressed against the heating plate 1, as shown in FIG. 6, when the cylindrical pipe 5 having no flat portion is pressed against the heating plate 1, the pipe 5 bites into the heating plate 1. The problem that the heating plate 1 becomes thin, and the heating plate 1 around the pressure contact part
This is to avoid the problem of swelling.

FIG. 1 (B ') shows a second embodiment of the present invention, in which the pipe 5 shown in FIG. 1 (B) is drawn by a pair of rollers 9 and the like to form a small diameter pipe 5'. The density of the magnesia 7 is increased. Subsequent manufacturing steps are the same as those in the first embodiment, and are shown in FIGS.
The processing shown in FIG. 2 is carried out, and heating and pressurization are performed in the same manner as in the first embodiment, and the heating plate 1 is pressed.

FIG. 2 is a schematic view for explaining a third embodiment of the present invention, in which a cross-section of the outer peripheral surface is formed in a non-circular shape having a flat surface portion 10a and an inner peripheral surface is formed in a circular shape. The pipe 5 is inserted into the aluminum-shaped heater holding base 10. Inside the pipe 5, a heater 6 and a magnesia 7 are inserted as in the first embodiment.

A heater holder 10 having a pipe 5 inserted therethrough.
As shown in FIG. 1 (D), the flat portion 10a is bent into a substantially ring shape, the flat portion 10a is brought into contact with the outer bottom surface of the heating plate 1, and the heater 6 is energized to heat to 200 to 560 degrees (Celsius). After that, the energization is stopped, the heater holding table 10 is pressurized to be deformed by compression, and the heating plate 1 is pressed. When the heater holder 10 is compressed and deformed, the gap between the inner surface of the heater holder 10 and the pipe 5 becomes extremely small, so that the heat generation amount of the heater 6 is efficiently transmitted to the heating plate 1.

FIG. 3 shows a modification of the third embodiment of the present invention. The cross section of the outer peripheral surface of the heater holder 11 has a non-circular shape in which the plate-like projections 11b project from both ends of the flat surface portion 11a. However, the other points are the same as those of the heater holder 10, and the pipe 5 is inserted and pressed against the heating plate 1.
The heater holder 11 has an advantage that it is easy to apply a pressing force to the plate-like protrusion 11b, and since the heater plate 1 is pressed against the heating plate 1 with a flat surface having a large area, the pressure contact surface has a large strength and the heater holder 11 is heated. There are advantages such as an extremely small amount of bite into the plate 1.

FIG. 3 shows a fourth embodiment of the present invention.
The heater holder 12 made of aluminum has a flat surface portion 12a formed on one side and two holding protrusions 12b formed on the other side. The heater holder 12 is bent into a substantially ring shape, and then the pipe 5 is bent into a similar shape.
Is inserted between the two holding protrusions 12b,
B is bent inward and the pipe 5 is tightened. Next, the flat part 1
2a is brought into contact with the outer bottom surface of the heating plate 1, and is heated and pressed to be brought into pressure contact with the heating plate 1 in the same manner as in the above-mentioned respective embodiments.

[0020]

Since the present invention is constructed as described above, it has the following effects. (1) When the heating plate is cast, the shape of the mold of the heating plate is simplified, the manufacturing cost of the mold is reduced, and quality defects such as shrinkage cavities and cracks that have occurred in the heating plate, which have been a problem in the past, are generated. Resolved. (2) The shape accuracy of the heating plate is improved, and the flat part formed on the pipe or the heater holding table to be pressed is pressed against the heating plate. The cost of manufacturing the heating plate has been reduced because the labor for doing so has become unnecessary. (3) Since the heater or the heater holder is pressed against the heating plate, the heat generated by the heater is efficiently transmitted to the heating plate. (4) Utilizing the force of pressing the heater against the heating plate, the pipe filled with the magnesia can be compressed and deformed to increase the density of the magnesia.

[Brief description of drawings]

1 (A) to 1 (D) and FIG. 1 (B ') are schematic views illustrating a manufacturing process of a first embodiment and a second embodiment of a method for manufacturing a sheathed heater according to the present invention.

FIG. 2 is a schematic diagram illustrating a third embodiment.

FIG. 3 is a schematic diagram illustrating a modification of the third embodiment.

FIG. 4 is a schematic diagram illustrating a fourth embodiment.

FIG. 5 is a vertical cross-sectional view of a main part of a pipe pressed against a heating plate.

FIG. 6 is a schematic view for explaining a state where a circular pipe is pressed.

FIG. 7 is a longitudinal sectional view of a main part showing a conventional example of a sheathed heater.

FIG. 8 is a perspective view of a heating plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating plate 5 Pipe 5'Small diameter pipe 6 Heater 7 Magnifier 8 Pipe 8a Flat part 10 Heater holding stand 10a Flat part 11 Heater holding stand 11a Flat part 11b Plate-like projection 12 Heater holding stand 12a Flat part 12b Holding projection

Claims (4)

[Claims] 1. A heater is inserted into an aluminum pipe, the gap between the heater and the pipe is filled with magnesia, and then the cross-sectional shape of the pipe is processed into a non-circular shape having a plane portion, and The heating plate is bent into a substantially ring shape capable of uniformly heating, then the flat surface of the pipe is brought into contact with the outer bottom surface of the aluminum heating plate, and the heater is energized to 200 to 560 degrees. A method for manufacturing a sheathed heater, characterized in that energization is stopped after heating, and the pipe is pressurized to compressively deform the pipe and press-contact with the heating plate. 2. A heater is inserted into an aluminum pipe, the gap between the heater and the pipe is filled with magnesia, and then the pipe is drawn into a small diameter pipe to increase the density of the magnesia inside. Along with, the cross-sectional shape of the pipe is processed into a non-circular shape having a plane portion, and the heating plate is bent into a substantially ring shape capable of uniformly heating, and then,
The flat portion is brought into contact with the outer bottom surface of the aluminum heating plate, the heater is energized to heat it to 200 to 560 degrees, and then the energization is stopped, and the pipe is pressed to press the heating plate. A method for manufacturing a sheath heater characterized by the above. 3. A coated heater in which a heater is inserted into a pipe, and a gap between the heater and the pipe is filled with magnesia, wherein the outer peripheral surface is formed into a non-circular shape having a flat surface portion and the inner peripheral surface is shaped. Is inserted into an aluminum heater holder having a circular shape, and then the heater holder is bent into a substantially ring shape capable of uniformly heating a heating plate, and a flat portion of the heater holder is formed. To the outer bottom surface of the heating plate, energize the heater to heat it to 200 to 560 degrees, and then stop energizing, pressurize the heater holder to compressively deform it and press-contact the outer bottom surface of the heating plate. A method for manufacturing a sheathed heater, comprising: 4. A heater holding base made of aluminum having a cross-sectional shape in which a flat surface portion is formed on one side and two holding protrusions are formed on the other side, and a substantially ring shape capable of uniformly heating a heating plate. The heater is inserted into the pipe, the heater is inserted into the pipe, and the gap between the heater and the pipe is filled with magnesia. Insert into the heater, and perform a caulking process to bend the tip of the holding projection toward the coated heater, and after energizing the heater to heat it to 200 to 560 degrees, energize is stopped and the flat surface of the heater holder is held. A method for manufacturing a sheathed heater, comprising: pressing a portion against an outer bottom surface of a heating plate to press-contact the outer bottom surface of the heating plate.