JPS5873985A - Sheathed heater and method of producing same - 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 1) Techniques of the Invention 11 This publication relates to a sheathed heater suitable for infrared radiation and a method for manufacturing the same.

2) Conventional technology and its advantages - IIIHC Schiff, c heater is made of iron and stainless steel.

Coils made of metal such as copper and aluminum
A heat-resistant electrical insulating powder such as magnesia or alumina is filled in the space between the heat-generating element and the seeds.

The heating element is prevented from deforming and electrically insulated. Further, both ends of the sheath are sealed with a closing body made of glass compound or the like, and lead terminals connected to the heating element kII are fixed.

In this case, since magnesia powder adsorbs hot air in the atmosphere at room temperature and releases moisture at high temperatures, which harms electrical insulation, it is necessary to dehydrate the seeds after filling the seeds with magnesia powder and seal the seeds. There is. However, if the seeds are sealed tightly, the heating element will consume oxygen while in use.
There was a drawback that the inside of the seed became a reducing atmosphere and the heating element evaporated, resulting in a short life. For this reason, even if a heating element is made of an iron-chromium alloy containing 4 to 6% aluminum and has a maximum operating temperature of 1,300°C in the atmosphere, if it is sealed in a sheath, a chemical coating will form on the surface of the heating element. Therefore, it is not possible to fully demonstrate its performance.

On the other hand, when metal sheaths are used, filling them with magnesia powder and then reducing the diameter has the advantage of increasing the packing density of magnesia and easily preventing accidents such as deformation, short circuits, and breakage of the heating element. Made seeds have a low heat resistance temperature.
As an infrared-first heat source, it has various disadvantages, such as not only not passing through the heat sink, but also exposing the radiation efficiency and polluting the inside of the furnace.

In contrast, seeds made of heat-resistant electrically insulating materials such as quartz, magnesia, and alumina can withstand high temperatures of 1000°C or more, are clean, and have high infrared transmittance and radiation efficiency.
- etc. are suitable for infrared 111F, but when filled with magnesia, it is not possible to reduce the diameter and increase the packing density like metal seeds, so the heating element is There were disadvantages such as the occurrence of entanglement accidents and the tendency for the seeds to break due to the difference in thermal expansion coefficient between the quartz seeds and the magnesia seeds.

3) The first feature of the JIa beak according to the invention was made in order to eliminate the drawbacks of the above-mentioned prior art, eliminating the need for filling with magnesia, etc., and improving the oxidation properties of the cormorant body. The purpose of this project is to provide a sheathed heater that has a long life, improves thermal efficiency by using a sheathed material with excellent infrared transmittance and radiation efficiency, and is easy to obtain high output. It is suitable for infrared furnaces.

A second object of the present invention is to provide a technique for fabricating a sheathed heater suitable for the purpose of the first invention into a container.
-4) Structure of the invention The first aspect of the present invention is that the seeds are made of a heat-resistant electric a-edge material,
A one-wound coil-shaped heating element made of heat-resistant aluminum and ram-containing heat-resistant steel having an oxide film on its surface is housed in this seed in a freely spaced manner.

The second aspect of the present invention is "Aluminium-containing heat-resistant metal-containing report"
Heating the coiled heating element in an oxidizing atmosphere!
The pre-oxidized heating element is placed in a sheath made of a heat-resistant electrical insulating material in a ventilated manner, and the oxidizing gas is injected into the sheath while electricity is applied to the heating element to generate heat. This is because an oxide film is formed on the surface.
-5)°1Ilj1 Example of the First Invention The details of the present invention will be explained below with reference to the illustrated embodiments.

(1) is a sheath made of, for example, a quartz tube with an inner diameter of 6 to 7 m;
(3) is a lead terminal made of, for example, a straight @12- iron-nickel alloy, which is supported by penetrating through these closing bodies (2) and 4 m, respectively; (4) is a lead terminal (
3) A tightly wound coil type heating element mounted between (3) and (3). As shown in N2WJ, the above-mentioned closed body is made of glass carp pound made by bonding magnesia powder with low point glass, welded to the lead body), and seeded (
The inner surface of 1) is bonded to the bonding layer (5), which is made of glass having the same composition as the bonding glass of the glass compound and forms an air-permeable filamentous structure. This closed structure and its manufacturing method
- The decision is detailed in the newsletter No. 84-44009 and the newsletter No. 1154-44010. 4-〇Remove a wire rod with a diameter of 8cm made of a heat-resistant alloy containing 1% aluminum.
It is tightly wound into a coil shape with five meshes, and as shown in No. 3 (3), an oxide film (6) is formed on the surface of the edge.

The close winding of the coil here includes a range from a state in which the wire spacing of the coil is 0 at room temperature to a state in which there is a slight gap at one end at room temperature, but the interline spacing is O at operating temperature.

Next, the effectiveness of this sheathed heater will be explained. When an operating voltage is applied between both lead terminals (3), (3), a voltage is also generated at one end of the coil. However, the heating element (4)
is electrically insulated because a strong oxide m(2) of aluminum is formed on the surface.

The first section of the coil is in close contact, but there is no short circuit. Also, the first heating element (4) generates heat, rises in temperature, and expands, but since both ends are identified, the first section of the coil is kept in a crimped state, but? Since there is no pitch unevenness, no temperature unevenness occurs. Furthermore, the seeds (1) are formed into a quartz tube and then filled with an insulating material such as magnesia.
Therefore, the infrared radiation emitted from the heating element (4) directly passes through the sheath (1) and is emitted, resulting in high efficiency. Also.

Since the sheath (1) is not filled with magnesia, there is no need to seal the sheath (1), and therefore, as described above, the closure body (2) is made breathable so that the internal atmosphere of the sheath (1) is communicated with the outside air to maintain an oxidizing property. The oxide film of the heating element (4) can be kept in a good state for a long time, so it has a long life.Incidentally, the 0)l-OFν cycle can be repeated for 2 minutes at 110% of the rated voltage. I did this for 4,000 @ and found no abnormalities.

6) Embodiment of the third invention Next, a method of manufacturing the sheathed heater of the above embodiment will be explained. An aluminum-containing heat-resistant alloy silver material is wound in a fixed manner to form a coil-shaped body (4). This heating element (
Connect both ends K and IJ terminals (3) of 4) and bake in a 1100 tl air oven for 2 hours to pre-oxidize both front and back sides of the heating element (4). Insert the oxidized heating element (4) into the sheath (1) and connect the lead terminal (3).

(8) are placed on both sides and ends of the sheath (1), and the layer S of the sheath (1) is filled with magnesia powder, which is then penetrated with a pongee glass to form a closed layer S made of glass compound. A breathable sublayer (5) formed on the body (8)
form. Next, a relatively low voltage is applied between both lead terminals (3) and (31) while flowing pure oxygen from one end of the sheath (1), and then this voltage is gradually increased until the rated voltage is reached. The current is applied for about 10 minutes at a voltage of 143% of the voltage. Then, the 11 heating element (for example, the rated value 6
．． A current of 9 µm flows against 3 µm, and the heating element (4) has a current of 1400 µm.
When heated to a high temperature of .degree. C. or higher, a strong oxide film (6) is formed on 1RII of the heating element (4). There, the electricity is turned off and the flow of oxygen is stopped.

In this single-piece manufacturing method, the coil-shaped heating element (4) is pre-oxidized and then installed inside the sheath (1), so when electricity is applied inside the sheath (1), the oxide film provides considerable electrical insulation. This allows for electrical heating without fear of short circuits. and.

During electrical heating in the sheath (1), since the -oka of the coil is in close contact with each other, the temperature can be raised uniformly and a uniform oxide film (6
) can be formed. Furthermore, since electrical heating is performed while oxygen is flowing through the sheath (1), dirt on the inside of the sheath (1) and on both sides of the heating element (4) is removed, and dirt caused by deterioration of the heating element (4) is removed. This has the advantage of eliminating abnormal cuts. Also,
Since the oxidation treatment is performed after the seeds (1) are packed, there is no risk of peeling or staining of the oxide film (6) due to handling. Any material that has both heat resistance and electrical insulation properties may be used, and its shape may be arbitrary, such as a circular tube or an elliptical tube.If the difference between the inner diameter of the sheath and the outer diameter of the heating element is too large, the heating element This is undesirable because it prevents close contact between the first and second parts. In addition, if the difference between the outer diameter of the heating element and the inner diameter of the sheath is too small, the coil of the heating element that expands during operation will have no place to escape. Although a closed body made of a glass compound is used, the present invention is not limited to this, and any type of body that supports the IJ + terminal in a ventilated manner may be used.Furthermore, the heating element may be made of aluminum-containing nichrome metal. , l! may be any heat-resistant alloy containing aluminum.Furthermore, it is particularly preferable that the wire spacing between the coils of one heating element be such that the spacing is such that when this heating element is used at a voltage somewhat lower than the rated voltage, In the case of , 1, there is a possibility that the oxidation II and oxidation in the sheath are poor and the connection between the lead terminal and the heating element is placed separately so that it may not be damaged.

In the manufacturing method ξ, the oxidation treatment inside the sheath may be performed by applying electricity to a heating element to generate heat, and heating from the outside of the sheath with a burner bed or the like, in this case.

Since there is no need for overcurrent energization, a relatively low voltage can be applied, and there will be no short circuit between the wires of the coil even in the early stages of energization when the film has not grown sufficiently.

Further, the atmospheric gas used for preliminary oxidation may be 12 elements,
Further, as long as the gas flowing within the sheath is also oxidizing, it is not limited to acid accumulation.

8) Effects of the Invention As described above, the sheathed heater of the present invention comprises a heat-resistant electrically insulating material as the sheath, and the sheath has an aluminum-containing heat-resistant, closely-wound coil type having a surface ξ oxidized film. Since the heating element is housed in a ventilated manner, there is no need to fill it with yam and magnesia as in the past.

In addition to being easy to clean, it eliminates abnormal disconnections due to contamination from magnesia and seeds, and damage to seeds due to thermal expansion of magnesia. In addition, quartz and alumina, which have excellent heat ray transmittance and radiation efficiency, can be used for the sheath, and heat-resistant alloys including aluminum, which could not be used in the past, can be used for the heating element, making the sheath heater suitable for infrared furnaces, etc. is obtained.

Furthermore, in a method of manufacturing a sheathed heater according to the present invention, a tightly wound coil-shaped heating element made of an aluminum-containing heat-resistant alloy is heated in an oxidizing atmosphere to preoxidize the surface.

This pre-oxidized heating element was placed in a sheath made of a heat-resistant electrical insulating material in a ventilated manner, and while an oxidizing gas was passed through the sheath, electricity was applied to the heating element to generate heat and form an oxide film on the surface of the heating element. Therefore, even though the heating element is in close contact with the coil, it has an electrical value of □'1.Since the heating element is oxidized by heating with electricity inside the generator without fear of circuit, it forms a strong oxide film with excellent electrical insulation properties. It has the advantage that it can be formed uniformly.

[Brief explanation of drawings]

ll1llIl is a cross-sectional view of one embodiment of the sheathed heater of the present invention, FIG. It is an enlarged cross-sectional m view. (1)...-seed (2)... Obstruction body (
3) - Lead terminal (4) - Heating element agent Patent attorney Bowl top - Male Figure 1

Claims (1)

[Claims] 1) A sheath made of a heat-resistant electrical insulating material, a pair of lead terminals fixed to both ends of the sheath in a ventilated manner,
The true value was taken as a wound coil type heating element made of aluminum J4 aluminum containing heat resistant alloy $111 and having an oxide film on both sides of the lead terminals. It is characterized by that. A sheathed heater. 2) The sheathed heater according to claim 11, wherein the heating element is made of iron, chromium, or aluminum. 3) The sheathed heater according to claim II, item 1, characterized in that the coil shape of the heating element has a line spacing of 11 degrees so that the coils are in close contact with each other at high temperatures during operation. 4) Made of an aluminum-containing heat-resistant alloy. Written mail @*Heat the coil-shaped heating element in an oxidizing atmosphere! Pre-oxidize the true
This pre-oxidized heating element is installed in a sheath made of J111-resistant electric candy material so as to be ventilable, and while an oxidizing gas is passed through the sheath, the heating element is overcharged and generates heat. A method for manufacturing a sheathed heater characterized by forming an oxide film on the body surface. 5) The oxidation of the heating element within the sheath is carried out by applying an overcurrent.
! A method for manufacturing a sheathed heater according to No. 4114. 6) The method of manufacturing a sheathed heater according to claim 4, wherein the oxidation of the heating element in the sheath internal sheathing ζ is carried out by heating the heating element from outside the sheath while applying an overcurrent to the heating element.