JPH06231873A - Sheathed heater with fin - Google Patents

Abstract

PURPOSE:To allow efficient manufacture without any need of strict dimensional control, and prevent the occurrence of uncomfortable creaking at the time of heat generation by directly inserting a heating wire and an electrical insulator in a pipe having fins as integral part thereof. CONSTITUTION:A heating wire 4 is inserted into an aluminum pipe 1 having a circular cross sectional form with fins 3 as integral part thereof, and the pipe 1 is further filled with an electrical insulator 6 such as magnesium powder. Both open ends of the pipe 1 are sealed with a sealing material 7. Thereafter, the pipe 1 is compressed under pressure. At this compression process, a pair of pressing molds are used to apply pressure from both upper and lower sides of the pipe 1. As a result of the application of pressure, the diameter of the pipe 1 is reduced, and the bulk density of the electrical insulator 6 is thereby increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheathed heater with fins provided with fins for heat exchange.

[0002]

2. Description of the Related Art A conventional sheathed heater with fins is shown in FIG.
As shown in FIG. 1 and FIG. 12, a sheath heater b is inserted into a pipe a in which a plurality of fins a1 are integrally formed, and the outer periphery of the pipe a is pressurized so that the inner peripheral surface of the pipe a is attached to the sheath heater b. It is closely attached to the outer peripheral surface.

[0003]

However, in such a conventional sheathed heater with fins, when the inner diameter of the pipe a is too large, a part of the peripheral surface of the pipe a is pressed when the outer periphery of the pipe a is pressurized. Distortion causes sheath heater b
The adhesiveness with the outer peripheral surface of the is deteriorated, and the efficiency of heat conduction from the sheath heater b to the pipe a is reduced. If the inner diameter of the pipe a is too small, it becomes difficult or impossible to insert the sheath heater b into the pipe a.
Therefore, the inner diameter of the pipe a must be strictly controlled, which complicates the manufacturing and increases the manufacturing cost.

Further, in such a conventional sheathed heater with fins, a pipe a is provided around the sheathed heater b.
However, when the sheath heater b generates heat, an unpleasant squeak noise is generated due to a slight expansion difference between the pipe a having the fin a1 formed therein and the metal pipe of the sheath heater b. .

The present invention has been made by paying attention to such a point, and an object thereof is to enable efficient production without requiring strict dimensional control, and to produce an unpleasant squeak noise when heat is generated. It is to provide a sheathed heater with fins that does not occur.

[0006]

In order to achieve such an object, the present invention inserts a heating wire into a metal pipe integrally formed with fins, and electrically insulates the heating wire. The filling density is increased and the pipe is compressed to increase the packing density of the electrical insulator.

[0007]

In such a structure, since the heating wire and the electric insulator are directly inserted into the pipe integrally formed with the fins, there is no problem even if the inner diameter of the pipe varies a little. In addition, the heat generated by the heating wire is efficiently and quickly conducted from the pipe to each fin, and since the sheath heater is not inserted in the pipe, it is caused by the difference in thermal expansion between the pipe and the sheath heater. No unpleasant squeak noise is generated.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 10.

FIG. 1 is a plan view of a sheathed heater with fins according to a first embodiment of the present invention, and FIG. 2 is a sectional view thereof, wherein reference numeral 1 is a pipe made of aluminum extruded material. On the peripheral surface of the pipe 1, a plurality of fins 3 projecting in mutually opposite directions and divided by the kerfs 2 are integrally formed.

A heating wire 4 spirally coiled is inserted into the center of the pipe 1, and pin-shaped terminals 5 are attached to both ends of the heating wire 4. Further, the pipe 1 is filled with an electric insulator 6 such as magnesia powder so as to surround the heating wire 4.

The openings at both ends of the pipe 1 are sealed with the sealing material 7.
The pipe 1 is compressed in order to increase the packing density of the electrical insulator 6 in the pipe 1 in this state.

Explaining the process of manufacturing such a sheathed heater with fins, as shown in FIGS. 3 and 4, first, the heating wire 4 is inserted into a pipe 1 having a fin 3 integrally and having a circular cross section. Further, the electrical insulator 6 is filled and the openings at both ends of the pipe 1 are sealed with the sealing material 7. Note that the pipe 1 made of an extruded material of aluminum has the fins 3 integrally formed up to the part shown by the chain double-dashed line in FIG. Since it is an unnecessary portion away from the pipe 1 and it is necessary to provide an installation portion for installing the pipe 1 on the device, the portion indicated by the chain double-dashed line is cut and removed.

Next, the pipe 1 is pressurized and compressed. For this compression processing, as shown in FIG. 5, for example, a pair of pressure dies a and b which are vertically divided are used, and the pipe 1 is pressed from above and below by the pressure fittings a and b to be compressed. To implement.

By this compression processing, the pipe 1 is transformed from the circular cross section shown in FIG. 4 to the substantially hexagonal cross section shown in FIG. 5 and its cross-sectional area is reduced, and the packing density of the electric insulator 6 inside is increased. The heat conduction between the heating wire 4 and the pipe 1 becomes good.

The compression processing of the pipe 1 can also be carried out by using a roll mill. In this case, as shown in FIG. 6, the pipe 1 is pressed from two directions by a pair of pressure rolls a and b. To compress. In this case, the diameter of the pipe 1 is reduced to increase the packing density of the electric insulator 6 inside, and a thickening portion 8 is formed on the outer periphery of the pipe 1 due to this compression processing.

FIG. 7 shows a sheathed heater with fins according to a second embodiment of the present invention. In the second embodiment, fins are projected on the peripheral surface of the pipe 1 in four directions, up, down, left and right. 3 is formed.

When the fins 3 project in four directions as described above, the pipe 1 is pressed from four directions by using four pressure rolls a, b, c and d as shown in FIG. To reduce the diameter and increase the packing density of the electric insulator 6 inside.
In this case, the thickened portions 8 are formed at four locations on the outer circumference of the pipe 1 according to the compression processing of the pipe 1.

Further, in this second embodiment, as shown in FIGS. 9 and 10, the fins 3 arranged in the longitudinal direction of the pipe 1 are alternately bent so as to incline to the opposite side. Fluid flowing around and each fin 3
It is also possible to improve the heat exchange rate by making good contact with.

The pipe used in the present invention is not limited to the extruded material of aluminum, but may be a drawn material of aluminum, or an extruded material or drawn material of another material that can be processed in the same manner as aluminum. And so on.

[0020]

As described above, in the sheath with fin of the present invention, since the heating wire and the electric insulator are directly inserted into the pipe integrally formed with the fin, the size of the inner diameter of the pipe can be reduced. Even if there is some variation, there is no problem, its dimensional control is easy and it can be manufactured efficiently, and since the heating wire is directly inserted into the pipe with the fin integrally formed, this heat generation The heat generated when the wire heats up is efficiently and quickly conducted from the pipe to each fin to improve the heat exchange rate.Furthermore, since the sheath heater is not inserted in the pipe unlike the conventional structure, the pipe and its There is an advantage that no unpleasant squeak noise is generated due to the difference in thermal expansion from the sheathed heater.

[Brief description of drawings]

FIG. 1 is a plan view showing a sheathed heater with fins according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a plan view of the pipe of the sheathed heater with fins before compression processing.

FIG. 4 is a sectional view taken along the line BB in FIG.

FIG. 5 is a cross-sectional view showing an example of means for compressing the pipe of the sheathed heater with fins.

FIG. 6 is a cross-sectional view showing another example of means for compressing the pipe of the sheathed heater with fins.

FIG. 7 is a plan view showing a sheathed heater with fins according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view showing an example of means for compressing a pipe of the sheathed heater with fins.

FIG. 9 is a cross-sectional view when the fins of the sheathed heater with fins are alternately bent and tilted in opposite directions.

FIG. 10 is a plan view of the same.

FIG. 11 is a perspective view of a conventional sheathed heater with fins in an exploded state.

FIG. 12 is a plan view showing an assembled state of the sheathed heater with fins.

[Explanation of symbols]

 1 ... Pipe 3 ... Fin 4 ... Exothermic wire 6 ... Electrical insulator

Claims (1)

[Claims] 1. A heat generating wire is inserted into a metal pipe integrally formed with fins, an electric insulator surrounding the heat generating wire is filled, and the pipe is compressed to perform the electric insulating material. A sheathed heater with fins that increases the packing density of.