JP2003347017A - Covered heater wire and electrothermal heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a covered heater wire having high safety, high flexibility, and high durability. <P>SOLUTION: This covered heater wire is provided with a heater wire 2, a first cover layer 3 provided on the surface of the heater wire 2, and a second cover layer 4 provided on the surface of the first cover layer 3. Since a double insulation structure can be made by the first cover layer 3 and the second cover layer 4, safety can be enhanced. In addition, since the first cover layer 3 and the second cover layer 4 are made of ceramic fiber and are highly flexible, bending the covered heater with a small radius becomes possible and a way of use by delicately arranging the covered heaters becomes possible too. Furthermore, since the first cover layer 3 and the second cover layer 4 can be rigidly integrated together, durability can be enhanced. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated heater wire and an electric heater, and more particularly, to a coated heater wire provided with a highly durable and electrically insulating coating layer and an electric heater using the coated heater wire as a heating element. It relates to a heater.

[0002]

2. Description of the Related Art An electric heater is used for heating or keeping high-temperature equipment and pipes warm, and is called a mantle heater, a ribbon heater or a jacket heater.

FIG. 3 shows an example of an electric heater. The electric heater 15 has a configuration in which heater wires 12 are arranged in a predetermined shape on a sheet-like base material 16, and the heater wires 12 are fixed to the base material 16 side by fixing yarns 17.
8 together with the cover member 19.

In this case, the base material 16, the fixing thread 17, the heat insulating material 18, and the cover member 19 are preferably made of a material having electric insulation and heat resistance. Further, a nichrome wire or the like can be used as the heater wire 12 as it is, but in order to obtain a highly safe electric heater 15, a coated heater wire having an insulating coating layer formed on the surface of the wire material is used. preferable.

In the electric heater 15, since uniformity of heating often becomes a problem when used, it is preferable to arrange the lines having a small calorific value more densely than to arrange the lines having a large calorific value roughly. . Therefore, as shown in FIG. 3, in order to reduce the line interval and form a dense array,
Must be bent with a small bending radius, so that the heater wire 12 is required to have high flexibility. In addition, the work of arranging and fixing the heater wires 12 on the base material 16 can be mechanized. For this purpose, the heater wires 12 suitable for mechanization are required.

[0006]

By the way, the conventional coated heater wire is often in the form of a sleeve formed by braiding ceramic fibers, particularly glass fibers, into a tubular shape as a coating layer. However, since such a coating layer is not integrated with the wire, it moves along the wire, and therefore, the workability at the time of arranging and fixing on the substrate becomes poor,
In particular, it is difficult to mechanize work. In addition, the durability of the coating layer often decreases.

[0007] In addition, a material in which a coating material is impregnated with a silicon resin or polytetrafluoroethylene to improve adhesion is also used, but the heat resistance and flexibility of the heater wire are lost, and the durability is reduced. . Further, as another example of the coated heater wire, there is a ceramic insulator formed in a cylindrical shape through which the heater wire is passed.
Since there is always a non-insulated portion between the insulators, the insulation is insufficient. There is also a major drawback that the weight of the electric heater increases.

The present invention has been made to solve the above-mentioned problems of the prior art, and provides a coated heater wire which is excellent in electric insulation and heat resistance and has flexibility, workability and durability. It is intended to do so. It is another object of the present invention to provide an electric heater having excellent heating uniformity and safety.

[0009]

In order to solve the above-mentioned problems, a coated heater wire according to the present invention comprises a heater wire and a felt-like coating layer made of ceramic fibers provided on the surface of the heater wire. Is adopted. Further, means is further provided which further comprises a coating layer made of ceramic fiber yarn, woven or knitted material on the surface of the coating layer. Furthermore, the electric heater according to the present invention has been developed in order to solve the above problems.
Means constituted by using the coated heater wire according to claim 1 or 2 as a heating element is adopted.

[0010]

The coated heater wire according to the present invention employs the above means, so that the surface of the heater wire is coated with a felt-like coating layer made of ceramic fibers. Further, the surface of the heater wire is covered with a felt-like coating layer made of ceramic fibers, and the surface is further covered with a coating layer made of ceramic fiber yarn, woven fabric or knitted fabric.
Further, in the electric heater according to the present invention, by adopting the above-described means, the heating element is constituted by the coated heater wire having the felt-shaped coating layer made of ceramic fiber on the surface of the heater wire. . further,
A heating element is constituted by a coated heater wire in which a felt-like coating layer made of ceramic fibers is provided on the surface of the heater wire and a coating layer made of ceramic fiber yarn, woven or knitted material is further provided on the surface.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have discovered that a felt-like coating layer formed using ceramic fibers has excellent adhesion to a wire and is firmly integrated with the wire. In addition, it has been found that the two layers are firmly integrated by further forming a second coating layer on the felt-like coating layer (first coating layer) by knitting ceramic fibers or the like.

A coated heater wire having such two coating layers is excellent in flexibility, workability and durability, and is most suitable for manufacturing an electric heater excellent in uniform heating property and safety. Upon confirmation, the present invention has been completed.

An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows an embodiment of a coated heater wire according to the present invention. The coated heater wire 1 is a double-insulated coated heater wire 1, and a ceramic fiber is provided on the surface of the heater wire 2. Forming a felt-like first coating layer 3 made of
On the surface of which a second coating layer 4 made of a knitted ceramic fiber or the like is formed.

As the heater wire 2, a normal nichrome wire, a nichrome wire having a surface plated with nickel, and other known wires can be used.

The felt-like first coating layer 3 can be formed, for example, by the following procedure. First, ceramic short fibers of 5 mm or less are put into a binder solution, stirred, and mixed to form a slurry. The heater wire 2 is immersed in and passed through the slurry to form a film of the slurry on the surface of the heater wire 2. Next, by drying the slurry-like film, the felt-like first coating layer 3 fixed to the surface of the heater wire 2 can be formed. These series of operations can be automated.

Since the felt-like first coating layer 3 is intricately entangled with short fibers, once formed, it can maintain a fixed state even if the binder disappears due to heating. For this reason, the binder used does not require heat resistance. That is, polyvinyl alcohol (P
An aqueous solution of a common binder such as VA), polyethylene oxide (PEO), silicon oxide, and sodium glycolate can be used. As a ceramic fiber to be used, a ceramic fiber having silica, alumina or the like as a main component, which has higher heat resistance than glass fiber, is preferable.

The thickness of the felt-like first coating layer 3 can be adjusted depending on the slurry concentration and the like, and is preferably 100 μm or more, more preferably 300 to 1000 μm.

The felt-shaped first coating layer 3 is fixed to the wire in a state where the fibers are entangled, and is very strong and has high flexibility. It does not peel off even when heated to a high temperature, and generates less fine powder. Therefore, it can be used as it is as a coated heater wire. However, it is preferable to form the second coating layer 4 on the first coating layer 3 in order to prevent the generation of fine powder and ensure the durability.

The second coating layer 4 is formed on the first coating layer 3 using ceramic long fibers. For example, by winding a twisted yarn of ceramic fiber, the second coating layer 4 made of yarn is wound.
Can be formed. In addition, a ribbon of ceramic fiber woven fabric is wound around the woven fabric to form a second woven fabric.
Can be formed. Alternatively, the second covering layer 4 made of a knit can be formed by braiding using a twisted yarn of ceramic fibers. Among them, the knitted second coating layer 4 can be formed firmly so as to tighten the first coating layer 3 and can be automatically braided by using a braiding machine. Excellent in point.

In the coated heater wire 1 according to this embodiment configured as described above, the relatively thin first coating layer 3 is firmly integrated with the heater wire 2 and is rich in flexibility. . Further, since the outer surface of the second coating layer 4 is formed of long fibers, it can be finished uniformly and smoothly, and is particularly excellent in machine workability. Furthermore, even after the binder has disappeared due to use at a high temperature, its properties hardly change. Therefore, it is excellent in durability, the first coating layer 3 and the second coating layer 4 do not peel off even when used repeatedly under severe conditions, and the generation of fine powder is extremely small.

FIG. 2 shows an embodiment of the electric heater according to the present invention. The electric heater 5 is constituted by using the above-described coated heater wire 1 according to the present invention as a heating element. .

That is, in the electric heater 5, the coated heater wires 1 are arranged in a predetermined shape on a sheet-like base material 6, and the coated heater wires 1 are fixed to the base material 6 side by fixing yarns 7. This is housed in a cover member 9 together with the heat insulating material 8. In this case, the base material 6, the fixing thread 7, the heat insulating material 8, and the cover member 9 are preferably made of a material having electrical insulation and heat resistance.

In the electric heater 5 according to this embodiment configured as described above, the coated heater in which the heating element is provided with the double coating layer (the first coating layer 3 and the second coating layer 4). Since the line 1 is used, the following effects are obtained.

First, since the entire electric heater 5 is lightweight and soft, it can be easily attached to and detached from the object to be heated. Also,
Since the coated heater wires 1 can be arranged densely, uniform heating is possible, which is particularly suitable when strict temperature control is required. Furthermore, since it is excellent in durability, it can be used for a long time even if it is frequently attached to and detached from the object to be heated.

Hereinafter, embodiments of the coated heater wire of the present invention and the electric heater of the present invention will be described with reference to FIG. 1 and FIG. Example 1 (Coated heater wire) As heater wire 2, wire diameter 0.4 m
m, a nichrome two-wire having a resistance value of 8.92 Ω / m was used as a binder, sodium glycolate was used as a binder, and as a short ceramic fiber, Isowool 1260 manufactured by Isolite Industry Co., Ltd., containing alumina and silica as main components was used. .
Ceramic fibers pulverized to 5 mm or less were added to a 2% by volume aqueous binder solution, and the mixture was stirred well to obtain a slurry having a concentration of 60% by weight. After the heater wire 2 was immersed in the slurry, it was taken out and dried at normal temperature to form a felt-like first coating layer 3 having a layer thickness of 500 μm.

As the ceramic long fiber, a fineness of 170 tex and a heat resistance temperature of 1, mainly containing silicon dioxide (95%).
A second covering layer 4 was formed by braiding with a braiding machine using a twisted yarn at 000 ° C., and a covered heater wire 1 having a double insulating structure shown in FIG. 1 was obtained. In order to check the insulation properties of the coating layers (the first coating layer 3 and the second coating layer 4), a dielectric breakdown voltage confirmation test was performed using a high-voltage generator. As a result, the dielectric breakdown voltage was 1400 V at room temperature. there were.

(Electric Heater) Using the obtained coated heater wire 1, an electric heater 5 shown in FIG. 2 was prepared. That is, the coated heater wires 1 having a length of 2.2 m were arranged on the base material (woven fabric) 6 at intervals of 5 mm, and fixed with the fixing yarn 7.
This was housed in a cover member 9 together with a felt-like heat insulating material 8 having a thickness of 15 mm. For the base material 6, the fixing thread 7, the heat insulating material 8 and the cover member 9, the above-mentioned ceramic fiber containing silicon dioxide as a main component was used.

(Heating test) A stainless steel pipe was used as a heated object, and the created electric heater 5 was wound therearound.
A heating test was performed using a single-phase AC voltage of 0 V to set the surface of the object to be heated to 800 ° C. Target 800 after about 20 minutes
° C was reached. Thereafter, the temperature distribution was measured, and it was confirmed that the temperature distribution was uniform. After maintaining at the set temperature for about 1 hour, the heating test is completed, and the electric heater 5 is removed.
As a result of observing the coating layers (the first coating layer 3 and the second coating layer 4) of the coating heater wire 1, no deterioration of the coating layer was observed. Further, the above-mentioned heating test and observation of the coating layer were repeated 10 times. No abnormality was observed, and it was confirmed that the initial state was maintained.

Example 2 (Coated heater wire)
The first coating layer 3 having a felt shape of μm was formed. As the ceramic long fiber, the composition is aluminum oxide 70%, silicon dioxide 30%, fineness 200 tex, heat resistance temperature 1
Using a twisted yarn at 300 ° C., a second coating layer 4 was formed in the same manner as in Example 1 to obtain a coated heater wire 1 having a double insulation structure. In order to check the insulation properties of the coating layers (the first coating layer 3 and the second coating layer 4), a dielectric breakdown voltage confirmation test was performed using a high-voltage generator. As a result, the dielectric breakdown voltage was 900 at room temperature.
V.

(Electric Heater) An electric heater 5 was prepared in the same manner as in Example 1. That is, the coated heater wires 1 having a length of 2.2 m were arranged on the base material (woven fabric) 6 at intervals of 7 mm and fixed with the fixing yarn 7. This was housed in a cover member 9 together with a felt-like heat insulating material 8 having a thickness of 20 mm. The above-described ceramic fibers containing aluminum oxide as a main component were used for the base material 6, the fixing thread 7, the heat insulating material 8, and the cover member 9.

(Heating test) A stainless steel pipe was used as a heated object, and the prepared electric heater 5 was wound therearound.
The surface of the object to be heated is 1000
A heating test was performed at a temperature of ° C. Target 1 after about 20 minutes
000 ° C. was reached. Thereafter, the temperature distribution was measured, and it was confirmed that the temperature distribution was uniform. After holding at the set temperature for about 1 hour, the heating test was terminated, the electric heater 5 was removed, and the coating layers (the first coating layer 3 and the second coating layer 4) of the coating heater wire 1 were observed. No layer degradation was observed. Further, the heating test and the observation of the coating layer were repeated 10 times, but no abnormality was observed, and it was confirmed that the initial state was maintained.

Example 3 (Coated heater wire)
The first coating layer 3 having a felt shape of μm was formed. 170 tex fineness, heat resistant temperature 400 as ceramic long fiber
The second coating layer 4 was formed in the same manner as in Example 1 using glass fiber yarns at a temperature of ° C. to obtain a coated heater wire 1 having a double insulating structure. In order to check the insulation properties of the coating layers (the first coating layer 3 and the second coating layer 4), a dielectric breakdown voltage confirmation test was performed using a high voltage generator. As a result, the dielectric breakdown voltage was 120 at room temperature.
It was 0V.

(Electric Heater) An electric heater 5 was produced in the same manner as in Example 1. That is, the coated heater wires 1 having a length of 2.2 m were arranged on the base material (woven fabric) 6 at intervals of 5 mm, and fixed with the fixing yarn 7. This was housed in a cover member 9 together with a felt-like heat insulating material 8 having a thickness of 15 mm. The above glass fibers were used for the base material 6, the fixing thread 7, the heat insulating material 8, and the cover member 9.

(Heating Test) A stainless steel pipe was used as a heated object, and the prepared electric heater 5 was wound therearound.
Using a single-phase AC voltage of 00 V to heat the surface of the
A heating test was performed. Target 40 after about 15 minutes
0 ° C. was reached. Thereafter, the temperature distribution was measured, and it was confirmed that the temperature distribution was uniform. After holding at the set temperature for about 1 hour, the heating test was terminated, the electric heater 5 was removed, and the coating layers (the first coating layer 3 and the second coating layer 4) of the coating heater wire 1 were observed. No layer degradation was observed. Further, the heating test and the observation of the coating layer were repeated 10 times, but no abnormality was observed, and it was confirmed that the initial state was maintained.

[0035]

According to the first aspect of the present invention, the coated heater wire according to the first aspect of the present invention is constructed as described above, and is provided with a felt-like coating layer made of ceramic fibers on the surface of the heater wire. The coating layer can be firmly integrated and high flexibility can be obtained. Therefore, it is highly safe and can be bent with a small bending radius, so that it is possible to use such a line that a line having a small calorific value is densely arranged.

The coated heater wire according to claim 2 is configured as described above, and a felt-like coating layer made of ceramic fiber is provided on the surface of the heater wire, and the ceramic fiber is further provided on the surface of the coating layer. By providing the coating layer made of yarn, woven fabric or knitted material, the same effect as the invention according to claim 1 can be obtained, and the inner coating layer and the outer coating layer can be firmly integrated. ,further,
The surface of the outer coating layer can be uniformly and smoothly finished, and in particular, can be excellent in machine workability. Further, the properties hardly change even when used at a high temperature, the durability is excellent, the coating layer does not peel off even when used repeatedly under severe conditions, and the generation of fine powder is extremely small.

Further, the electric heater according to a third aspect of the present invention is configured as described above, and uses the coated heater wire according to the first aspect as a heating element, or the coated heater according to the second aspect. Since the heater wire is used as the heating element, a covered heater wire that is highly safe and can be bent with a small bending radius can be used as the heating element. Therefore, it is possible to use the wires having a small calorific value in a dense arrangement, so that the object to be heated can be uniformly heated, and this is particularly effective when strict temperature control is required. Furthermore, since durability is excellent, stable performance can be obtained for a long period even if attachment and detachment to and from the object to be heated are frequently repeated.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a coated heater wire according to the present invention.

FIG. 2 is a schematic view showing an embodiment of an electric heater according to the present invention.

FIG. 3 is a schematic view showing an example of a conventional electric heater.

[Explanation of symbols]

1 ... Coated heater wire 2, 12 ... heater wire 3. First coating layer 4... Second coating layer 5, 15 ... electric heater 6, 16 ... substrate 7, 17 ... fixed thread 8, 18 ... thermal insulation 9, 19 ... Cover member

Continuation of front page    (72) Inventor Hiroshi Nakamura             Mitsui Mining, 3-3-3 Toyosu, Koto-ku, Tokyo             Yama Material Co., Ltd. (72) Inventor Toshio Ishizuka             6-3-17 Soshigaya, Setagaya-ku, Tokyo F term (reference) 3K034 AA12 AA22 BA06 BA10 BA17                       BB05 BB06 GA03 JA09                 3K092 QA05 QB26 QB62 QB70 RE03                       RE05 VV06 VV25 VV40                 4L048 AA02 AA03 AA53 AB01 AC14                       BB01 CA06 DA29

Claims (3)

[Claims] 1. A coated heater wire comprising: a heater wire; and a felt-like coating layer made of ceramic fibers provided on a surface of the heater wire. 2. The coated heater wire according to claim 1, further comprising a coating layer made of ceramic fiber yarn, woven or knitted on the surface of the coating layer. 3. An electric heater comprising the covered heater wire according to claim 1 or 2 as a heating element.