JPS61131389A - Bandless band heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention Technical Field The present invention relates to an inner plate that surrounds an object to be heated, an outer plate that surrounds the inner plate, and a mica plate that is disposed between the inner plate and the outer plate. This invention relates to a band heater having an electrically insulated heating wire.

PRIOR ART This band heater functions to heat an object surrounded by an inner plate using heat generated from a heating wire. Band heaters such as the one shown are well known. In the same figure, a band heater 4 having a heater 1 and a band 3 supporting the heater 1 and having a tightening screw 2 is attached in close contact with an object to be heated 5 under the tightening action of the tightening screw 2. ing. The object to be heated 5 is heated by a heater 1 that generates heat by supplying power from a lead wire 6 . However, as shown in the figure, this band heater 4 has protrusions such as a threaded portion 7 and a portion of the lead cover 8, and thus requires a corresponding space when attached.

However, in recent years, it has become necessary for objects to be heated, such as plastic injection molding machines or molds, to take up as little space as possible around the object, and from this point of view, the above-mentioned Conventional band heaters cannot be said to be suitable for use.

As a heater that solves this problem, a cylindrical heater as shown in FIG. 2 is conventionally known.

As shown in the figure, this heater 9 does not require a threaded portion, and the lead cover portion 8/ does not protrude excessively, so it can be used even in a narrow space. However, since this heater 9 is used by being inserted into the object to be heated from the side, its adhesion to the object to be heated is poor.

Furthermore, when the temperature rises due to energization, the adhesion further deteriorates due to thermal expansion. In this case, since the heater is in a dry state, the thermal efficiency deteriorates and at the same time the life of the heater is shortened.

Purpose In view of the above points, an object of the present invention is to provide a heater that can be used even in a narrow space and has good thermal efficiency.

The purpose of this structure is to make the coefficient of thermal expansion of the outer plate that makes up the heater larger than the coefficient of thermal expansion of the inner plate that also makes up the heater, so that when heated with electricity, the heater contracts inward due to thermal expansion. This can be achieved by doing.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail based on drawings showing embodiments thereof.

In FIG. 3, the bandless band heater 11 has an inner plate 12 and an outer plate 13, and between these side plates,
As shown in FIG. 4, a heating wire 15 wound around a core mica plate 14 is arranged.

A mica plate 16 as an insulator is placed between the heating wire 15 and the side plates 12 and 13. The heating wire 15 generates heat when power is supplied from the lead wire 6. Outer plate 13
is made of a material with a coefficient of thermal expansion larger than that of the inner plate 12. Therefore, when the heating wire 15 generates heat, the difference in thermal expansion between the inner plate 12 and the outer plate 13 causes the heater to 11 contracts inward.

Since the bandless band heater 11 according to this embodiment has the above-described structure, when the object to be heated is inserted inside the inner plate 12 and then energized, the object to be heated is heated by the heat generated by the heating wire 15. Ru.

At this time, since the heater 11 contracts inward as described above, the adhesion between the inner plate 12 and the object to be heated is improved. Therefore, heating can be performed extremely efficiently without worrying about dry baking. Furthermore, as is clear from FIG. 3, the heater 11 does not require any protruding parts such as threaded parts found in conventional band heaters, so it can be used even in narrow spaces. Furthermore, since the band 3 having the tightening screw 2 is not required, it is economically cheaper to manufacture.

The above embodiment is a case in which the present invention is applied to a so-called mica heater using a mica plate as an electrical insulator, but as shown in FIG. It goes without saying that the present invention can be practiced with other heaters.

Effects As described above, according to the present invention, the coefficient of thermal expansion of the outer plate of the band heater is made larger than the coefficient of thermal expansion of the inner plate, so that when heating the object, the entire band heater contracts inward. , the band heater and the heated object are in close contact,
Therefore, thermal efficiency is greatly improved.

Further, since there is no need for fastening means such as tightening screws for making the parts tightly fit, the manufacturing cost is reduced accordingly, and there is no protruding part, which is advantageous in terms of space.

[Brief explanation of drawings]

Fig. 1 is a front view showing a conventional band heater, Fig. 2 is a perspective view showing a conventional cylindrical heater, Fig. 3 is a perspective view of a bandless band heater showing an embodiment of the present invention, and Fig. 4 is a perspective view showing a conventional cylindrical heater.
The figure is a sectional view taken along the line A-A of the heater shown in FIG. 3, and FIG. 5 is a sectional view of a main part of another heater in which the present invention can be practiced.

Claims (1)

[Claims] In a band heater that has an inner plate surrounding an object to be heated, an outer plate surrounding the inner plate, and an electrically insulated heating wire arranged between the inner plate and the outer plate, the thermal expansion of the outer plate A bandless band heater characterized by having a coefficient of thermal expansion larger than the coefficient of thermal expansion of the inner plate.