JPH05152061A - Cartridge heater - Google Patents

Abstract

PURPOSE:To provide a long-life cartridge heater, while ensuring inexpensive and compact constitution by use of a single U-shaped heating coil. CONSTITUTION:Regarding a single U-shaped heating coil 2, an (x-y) cross section is assumed, provided that a direction where coil sections are faced to each other, is taken as an x-direction, and a direction orthogonal with the x-direction is taken as a y-direction. In this case, a cartridge is constituted of an elliptical cylinder tube having an elliptical cross sectional form with an x-axis larger than a y-axis. According to this construction, heat transfer efficiency for each section can be made uniform, and a temperature difference between each coil section can be reduced. Also, a partial temperature rise in the heating coil 2 can be restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cartridge heater structure.

[0002]

2. Description of the Related Art FIG. 4A is a vertical (longitudinal) sectional view showing the structure of a conventional cartridge heater of this type.
FIG. 4B is a transverse cross-sectional view showing the MM ′ cross section of FIG. In the figure, 1 is a pipe forming the outer diameter of the cartridge heater, 2 is a U-shaped heating coil, 3
Is a power supply connection terminal connected to each end of one heating coil 2 having a U shape, 4 is magnesia powder filling the inside of the pipe 1, and 5 is a pipe 1 through which each power supply connection terminal 4 is passed.
The sealing material which seals the open mouth of is shown.

Next, the operation will be described. When the power source is connected to the power source connecting terminal 3, the heat generating coil 2 generates heat, the heat is transferred to the surface of the pipe 1 through the magnesia powder 4, and is radiated to the outside to heat the outside. The heating coil 2 has a U-shape, and is arranged substantially at the center of the true cylindrical pipe 1. That is, in the vertical direction of the drawing in FIG. 4 (A), the a point of the outer diameter of the pipe, the b point of the heating coil, the c point of the heating coil, and the d point of the outer diameter of the pipe are substantially equidistant. It is arranged so as to be located at.

However, as shown in FIG. 4 (B), since the conventional cartridge heater uses a true cylindrical pipe as the pipe 1, the distance from the position of the heating coil 2 to the outer diameter of the pipe 1 is In the cross section, the distance in the vertical (x) direction of the drawing is not the same as the distance in the horizontal (y) direction of the drawing, and the distance in the y direction is longer than the distance in the x direction. Therefore, heat transfer at point f in the figure is worse than at point e, and at point g where the U-shaped heating coil 2 faces, mutual heat interference between the heating coils 2 and the surrounding thick magnesia powder layer The highest temperature.

[0005]

Since the conventional cartridge heater as described above is constructed as described above,
Due to the difference in heat transfer efficiency, a temperature difference occurs in each part of the heating coil during energization, and in the part with poor heat transfer efficiency, the heating coil becomes too hot, which shortens the life of the device.

Even if the heat capacity is the same, the device life can be extended by lengthening the heat generation length of the heater, but the cost increases and the size increases, which makes it difficult to store the product in each product. To do.

Further, three or more heat generating coils are arranged so that the respective positions of the heat generating coils are located at equal distances from the outer diameter of the pipe, and the cross sections thereof are evenly positioned on the circumference coaxial with the pipe. Although a method of providing it may be considered, the structure becomes complicated and the cost becomes high.

The present invention has been made in order to solve the above problems, and uses one U-shaped heating coil to equalize the heat transfer efficiency of each part as much as possible, and is compact and has a long life. It is intended to provide a cartridge heater.

[0009]

In a cartridge heater according to the present invention, the direction in which one heating coil of one U-shaped heating coil faces each other is the x direction, and the direction perpendicular to this x direction is the y direction. Assuming an xy cross section,
The elliptic cylindrical pipe whose cross-sectional shape is an elliptical shape in which the y-direction is shorter than the x-direction is used.

[0010]

The cartridge heater according to the present invention comprises an elliptic cylindrical pipe whose cross-sectional shape is an elliptical shape in which the y-direction is shorter than the x-direction. It is possible to equalize the transmission efficiency.

[0011]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a longitudinal (longitudinal) sectional view showing the structure of a cartridge heater according to an embodiment of the present invention.
FIG. 1B is a transverse cross-sectional view showing the MM ′ cross section of FIG. In the figure, 1 is a pipe in this embodiment, 2 is a U-shaped heating coil, 3 is a power supply connection terminal connected to each end of a U-shaped heating coil 2, 4 Is magnesia powder filling the pipe 1
Indicates a sealing material that penetrates each power supply connection terminal 4 and seals the opening of the pipe 1.

As shown in FIG. 1, in the cartridge heater of this embodiment, one U-shaped heating coil 2 has a direction in which the heating coils 2 face each other in the x direction, and a direction perpendicular to the x direction. Assuming an xy cross section with the y direction as the y direction, the cross section is formed by the elliptic cylinder pipe 1 having an elliptical shape in which the y direction is shorter than the x direction. With this configuration, a, d, and
The points e and f are located substantially evenly from the heating coil 2. In addition, the heating coils 2 face each other g
Also in terms of the point, the surrounding magnesia powder layer can be made thin, and as a result, the temperature difference between the respective parts of the heating coil 2 can be reduced, and an abnormal temperature rise of the heating coil 2 can be suppressed, and the life of the device can be extended.

Next, the manufacturing process of the cartridge heater shown in FIG. 1 will be described. FIG. 2 is a diagram for explaining the manufacturing process. In the figure, the same reference numerals as those in FIG. 1 denote the same parts, and 10 and 11 denote molding dies. The conventional cartridge heater shown in FIG. 4 is manufactured in the same manner as the conventional one, and as shown in FIG. 2A, the concave mold 10 and the flat mold 1 are manufactured.
1 and the flat mold 11 is pressed with a pressure p from above, and flatly pressed as shown in FIG. 2 (B) to manufacture. At least the portion where the heating coil 2 is arranged inside the pipe 1 may be pressed flat.

Example 2. In the first embodiment described above, the case where the pipe 1 is not subjected to the diameter reduction processing is described. However, in the manufacturing process of a general cartridge heater, after the heating coil 2 is inserted into the pipe 1 and the magnesia powder 4 is filled. A step of reducing the diameter of the pipe 1 by using a roller or the like to compress the magnesia powder 4 therein is taken. Therefore, with respect to the material to be reduced in diameter, it is sufficient to compress it in the y direction while observing the state using a pressing machine or the like and flatten it until it becomes a predetermined dimension.

Example 3. FIG. 3 is a diagram for explaining a third embodiment of the present invention, the same reference numerals as those in FIGS. 1 and 2 designate the same or corresponding portions, and 20 is a pipe in the third embodiment. In each of Examples 1 and 2 described above, the heating coil 2 is inserted into the pipe 1, the magnesia powder 4 is filled, and then the pipe 1 is pressed to be processed into a flat shape. Becomes flat. In the third embodiment, in order to avoid this, the flat heating of the heating coil 2 is prevented by inserting the heating coil 2 into the pipe 20 which has been processed into a flat shape in advance and filling it with the magnesia powder 4.

[0016]

Since the cartridge heater according to the present invention is constructed as described above, it is possible to make the heat transfer efficiency of each part uniform while using one U-shaped heating coil. There is an effect that a temperature difference between the respective parts can be reduced and a partial temperature rise can be suppressed, and a cartridge heater which has a long life and is compact and inexpensive can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment and a second embodiment of the present invention.

FIG. 2 is a drawing for explaining the manufacturing process of the cartridge heater according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional cartridge heater.

[Explanation of symbols]

 1 Pipe 2 Heating Coil 3 Power Supply Connection Terminal 4 Magnesia Powder 5 Sealing Material 10 Molding Mold 11 Molding Mold 20 Pipe

Claims (3)

[Claims] 1. A cartridge heater in which one U-shaped heating coil is inserted into a cylindrical pipe whose one end is closed, and a filling material is enclosed in the pipe, wherein the cartridge heater has the U-shape. The direction in which the heating coils of one heating coil face each other is the x direction, and the direction perpendicular to this x direction is y.
In the case of assuming an xy cross section as a direction, at least the portion where the heating coil is located inside the cylindrical pipe is pressed to deform its shape, and the cross sectional shape of the portion is shorter in the y direction than in the x direction. An elliptical cartridge heater. 2. A cartridge heater in which a U-shaped heating coil is inserted into a cylindrical pipe whose one end is closed, and a filler is enclosed in the pipe to reduce the diameter of the pipe. The direction in which the heating coils of the one U-shaped heating coil face each other is the x direction, and the direction perpendicular to the x direction is y.
In the case of assuming an xy cross section as a direction, at least the portion where the heating coil is located inside the cylindrical pipe is pressed to deform its shape, and the cross sectional shape of the portion is shorter in the y direction than in the x direction. An elliptical cartridge heater. 3. A cartridge heater in which a U-shaped heating coil is inserted into a pipe whose one end is closed, and a filling material is enclosed in the pipe. Assuming an xy cross section in which the direction in which the heating coils of one shaped heating coil face each other is the x direction and the direction perpendicular to this x direction is the y direction,
A cartridge heater characterized in that it is configured by using an elliptical pipe whose cross-sectional shape is shorter in the y direction than in the x direction.