JPS6232593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a cartridge heater with significantly improved lifespan.

A conventional cartridge heater is constructed as shown in FIG. In Fig. 1, 1 is a metal pipe, 2 is a tip sealing fitting, 3 is a guide core, and 4 is a metal pipe.
5 is a highly insulating powder, 5 is a core, 6 is a heating wire, 7 is an electrode wire, and 8 is an unsealed end, where the heating wire 6 wrapped around the core 5 and the electrode wire 7 inserted into the through hole are connected. The completed core is fixed in the center of the metal pipe 1 by a guide core 3, and after filling the periphery of the completed core with a high-insulating powder 4, compression rolling processing and swaging processing are performed to create a highly insulating core. Powder 4
The packing density was improved.

However, since the diameter of the particles of the highly insulating powder 4 is generally 50 to 320 microns, it is necessary to prevent the largest particles of the highly insulating powder 4 from getting caught between adjacent wires of the heating wire 6 and creating a partial gap. In addition, the distance between adjacent heating wires 6 must be set to at least 320 microns. If a gap is created between adjacent wires of the heating wire 6, the wire temperature of this portion of the heating wire will rise compared to other portions, and the life of the heating wire 6, that is, the life of the cartridge, will be significantly reduced. There is a drawback.

In addition, in the case of a cartridge with a high voltage, low capacity rating, and a short effective heating section, the winding pitch of the heating wire 6 (between adjacent wires) becomes narrow, so it is not possible to increase the winding pitch to 320 microns or more. Ta.

In order to eliminate the drawbacks of the conventional example, the present invention eliminates spaces by completely covering the gaps between the heating wires 6 wound at a uniform pitch with dipping, thereby preventing the generation of localized high heat in the heating wires. The present invention provides a method for manufacturing a cartridge heater that can significantly extend the life of the cartridge heater and expand its rating. Hereinafter, embodiments will be described in detail with reference to the drawings.

2, 3, and 4 show one embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same parts. First, the core 5 shown in Figure 2
A heating wire 6 is wound around the core at a uniform pitch, and an electrode wire 7 is inserted into the through hole to form a completed core as shown in FIG. Next, magnesia 9 formed into a sheet shape as shown in FIG.
After compressing it slightly from the outer periphery so as to bite into it,
Sinter at a predetermined temperature (see Figure 5). This sintering causes the magnesia 9 to shrink by about 15%, so that the surface of the heating wire 6 is completely covered and gaps between the heating wires 6 can be eliminated. Furthermore, this completed core is inserted into a metal pipe 1 as shown in Fig. 6, the high insulation powder agent 4 is filled around it, and the pipe 1 is compressed to reduce its diameter by rolling or swaging to achieve high insulation. After improving the packing density of the powder agent 4, dehumidification is performed and the terminal sealing portion 8 is processed.

As described above, in the present invention, sheet-shaped magnesia is wrapped around a completed core, and the sheet-shaped magnesia is compressed slightly from the outer periphery so that a heating wire is bited into it, and then sintered at a predetermined temperature. The approximately 15% contraction of magnesia during sintering completely and tightly covers the surface of the heating wire, so it is possible to completely cover the heating wire with magnesia in an extremely simple process. Therefore, no voids are created around the heating wire, extending the life of the heating wire, and it is also easier to fill the completed core with the highly insulating powder after inserting it into the pipe, which has the effect of significantly improving work efficiency. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional cartridge heater, FIG. 2 is a sectional view of the core of the cartridge heater of the present invention, FIG. 3 is a sectional view of a completed core, and FIG.
The figure is a perspective view of sheet-like magnesia, and FIG.
FIG. 6 is a cross-sectional view of the completed core wrapped with sheet-like magnesia, and FIG. 6 is a cross-sectional view of the cartridge heater of the present invention. 1... Metal pipe, 5... Core, 6... Heating wire, 7... Electrode wire, 9... Sheet magnesia.

Claims (1)

[Claims] 1. A heating wire is wound at a uniform pitch around a core made by sintering magnesia so as to have two parallel through holes, and a sheet is placed around the entire circumference of the completed core with electrode wires arranged in the through holes. The core was wrapped with shaped magnesia, compressed slightly inward from the outer circumference, then sintered, and the completed core with voids removed by shrinkage due to magnesia sintering was placed inside the pipe, and the gaps were filled with insulating powder. A method for manufacturing a cartridge heater, characterized in that: