JPS5919420B2 - Cartridge heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cartridge heater, and its purpose is to maintain a narrow and uniform gap between the resistance coil wound around the completed core and the inner wall surface of the exterior. There is less risk of damage to parts inside the pipe.
The aim is to obtain a product with a long life.

Conventionally, in a cartridge heater, as a means for connecting a plurality of completed cores each having a resistance coil wound thereon, a guide core having a peripheral edge protruding from the outer diameter of the completed core is placed between two completed cores each having two resistance coils wound thereon. There are those in which the outer peripheries of each completed core are arranged and connected so as to fit and hold, or those in which the completed core is centrally held in an exterior pipe by a guide core with the electrode wire as an axis.

However, in the former method, a guide core is fitted and fixed to the outer periphery of the end of the core around which a resistance coil is wound, and is held in the exterior pipe, but the core itself is a molded product made of solidified powder, so the dimensions are unstable. It is uniform, and the fitting clearance between the completed core and the guide core that are connected and fixed must be large, and even if the completed core unit is inserted into the center of the exterior pipe, there is a large gap and there is so-called wobbling. The eccentricity of the resistance coil cannot be adequately controlled, and the guide core is thin and complex in shape, making it prone to chipping and cracking. In addition, in the latter case, which uses a guide core with the electrode wire as an axis and holds it inside the exterior pipe, due to the unevenness of the linearity and hardness of the electrode wire, the resistance coil is also coaxial with the center of the exterior pipe on the inner wall of the outer pipe. It is difficult to hold and fix with uniform gaps. The present invention eliminates the drawbacks of the conventional products as described above, and its structure will be explained below with reference to the drawings shown as an embodiment.

Reference numeral 1 denotes a magnesia powder sintered core, in which two mutually parallel through holes 2 are formed in the longitudinal direction.

Reference numeral 3 denotes a pair of fan-shaped fitting recesses formed at both ends of the core 1 by secondary processing, and are fan-shaped from the center of the end surface to both sides.

Reference numeral 4 denotes a resistance coil wound around the outer periphery of the core 1, and both ends of the coil are drawn into the through hole 2 through coil drawing slits 5 provided at both ends of the core 1, respectively.

Reference numeral 6 denotes a guide core for connecting the completed core 7 after winding of the resistance coil 4 is completed, and is formed into a fan shape so as to closely fit into the fan-shaped recesses 3, and the outer edges of the fan shapes are aligned with the periphery of the completed core. It is formed so as to protrude slightly, and is connected by fitting both fan-shaped recesses 3 of each of the two completed cores to both sides of the guide core 6.

8 is a through hole provided in the guide core 6, which is similar to the through hole 2 in the core 1.
It communicates with

Reference numeral 9 denotes an electrode wire that passes through the through hole 2 and the through hole 8, and connects the two completed cores 7 together with the guide core 6.
The slit 5) is in line contact with the drawn-in resistance coil 4.

10 is an exterior pipe whose one end is welded to a metal fitting 11, and the completed core 7 that has been connected is connected to the outer peripheral surface of the completed core 7 and the exterior pipe 10 by means of both fan-shaped outer peripheral edges of the guide core 6.
The magnet is inserted and held so that the inner wall surface of the magnet is spaced uniformly along the entire circumference, and the gap is filled with magnesia powder 12.

FIG. 7 shows the outer diameter of the exterior pipe 10 being compressed by swaging or the like after being filled with magnesia powder, and 13 is a die of the swaging machine. The packing density of the magnesia powder is increased by swaging, and the ends of the resistance coils 4 drawn into the through holes 2 (through the slits 5) are pressed against the electrode wires 9. Thereafter, the open end of the exterior pipe 10 through which the electrode wires are drawn out is annealed (dehumidified) and sealed with a heat-resistant insulating material 14 to complete the cartridge heater. Since the present invention adopts the above configuration, the two completed cores can be reliably connected by the guide core and the electrode wire, and the fan-shaped outer edge of the guide core that slightly protrudes from the outer periphery of the completed core allows the guide core to be connected to the guide core. A narrow gap between the outer peripheral surface and the inner surface of the exterior pipe can be maintained uniformly.

Therefore, compared to conventional products, the resistance wire and wire temperature can be lowered to effectively conduct the required amount of heat to non-heated objects, making it possible to obtain a product with a long life. Winding and connection between the guide core and the completed core are easy, and assembly is simple.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional side view showing an embodiment of a cartridge heater according to the present invention, Fig. 2 A shows a core used in the present invention, A is a front view, and an opening is a perspective view. 3 and 3 show the same guide core, A is a front view, the mouth is a perspective view, and FIG. 4 is a side view of the completed core, with main parts cut away. FIG. 5 shows the connection part of the completed core, with A being a side view, opening, and C being a sectional view. FIG. 6 is a cross-sectional view of a main part showing a state in which the completed core of FIG. 5 is inserted into an exterior pipe, and FIG. 7 is a side view showing a state of swaging, with the main part cut away. DESCRIPTION OF SYMBOLS 1...Core, 2...Through hole, 3...Double fan-shaped recess, 4...Resistance coil, 5...Slit, 6...
... Guide core, 9 ... Electrode wire, 10 ... Exterior pipe.

Claims (1)

[Claims] 1. A resistor coil-wound core made of sintered magnesia powder and having two parallel electrode wire through-holes is provided with fan-shaped recesses on both sides, and these two resistor coil-wound cores are , connected through a double fan-shaped guide core that can be freely fitted into the double fan-shaped recesses and has two electrode wire holes, and penetrates the two electrode wires;
A cartridge heater that maintains a uniform gap between the resistance coil and the inner wall surface of the pipe in an exterior pipe by using the outer edge of the guide core that protrudes slightly from the outer periphery of the core wrapped with resistance wire as a guide. 2 At the ends of the core around which the resistance coil is wound, a lead-in slit is provided that communicates with the two electrode wire holes, and the ends of the resistance coil and the electrode wire are constricted within the holes by swaging an exterior pipe, etc. The cartridge heater according to claim 1, characterized in that the cartridge heater is brought into pressure contact by.