JPS5836157Y2 - Refractory material for embedding the heating element - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a refractory in which a heating element is embedded.

FeA1-Cr heating elements have a high oxidation resistance limit temperature and are suitable for high-temperature use, so they are used as hot plates or heaters in various furnaces and other devices.

Apart from this good characteristic, Fe-Al-Cr heating elements have weak mechanical strength at high temperatures, and therefore have many problems with the means for supporting the heating element.

Conventionally, as means for supporting the heating element, an insulator is attached to a support bar fixed to the furnace outer shell, and the heating element is suspended from the insulator. Due to mechanical weakness and early deterioration of the heating element, it becomes deformed or breaks, making it incapable of generating heat, making it impossible to use it reliably for a long period of time.

Furthermore, due to the coarsening of the crystal grains of the heating element during high-temperature use, it becomes a cell at room temperature, and the heating element often breaks during the process of lowering and raising the temperature.

Furthermore, when the heating element exposed in the furnace is directly affected by the outside air and the atmosphere inside the furnace, the temperature of the heating element decreases, and when the temperature rises, the heating element 9 rapidly expands and contracts, causing an oxide film on the surface of the heating element. It will peel off and consume the AI of the Fe-Al-Cr heating element, but since this Alrji is an effective ingredient for heat resistance and low volume resistivity, the heat resistance effect will fade with use over time. In addition, the prior art has the disadvantage that output decreases due to an increase in electrical resistance.

Because of these drawbacks, instead of suspending Fe-Al-Cr metal heating elements from support bars, Fe-
It is important to completely bury the Al-Cr metal heating element.

However, even in this method, due to the lack of mechanical strength of the FeAl-Cr heating element at high temperatures, the wire often breaks due to the resistance of the refractory during expansion and contraction.

Separately, attempts have been made to sandwich the heating element between refractory sheets, but the atmosphere between the opposing sheets causes coarsening of the crystal grains of the heating element and peeling of the oxide film on the surface of the heating element. , disconnection and deterioration of heat resistance effect are inevitable.

Therefore, the purpose of this invention is to transfer a part of the outer circumferential surface of a heating element made of a spirally wound Fe-AlCr metal wire to a heated part, in order to overcome the drawbacks of the prior art described above. An object of the present invention is to provide a refractory in which a heating element is embedded, the heating element being exposed so as to enable direct heating, and the remainder of the heating element being buried in a support made of the refractory.

An embodiment of this invention will be described with reference to the accompanying drawings.

A refractory 1 in which a heating element is buried has a heating element 2 made of a Fe-Al-Cr metal scrap wire, and a support 3 made of a refractory such as a firebrick or ceramic fiber that holds the heating element 2. .

The heating element 2 has a spirally wound coil shape, and the support 3
The heating element 2 is embedded in the support 3 in a manner close to the inner wall surface 4 of the heating element 2.

In this burying, a part 5 of the outer surface of the heating element 2 made of a spirally wound Fe-AlCr metal wire is buried in the object to be heated 6.
The remainder of the heating element 2 is exposed to allow direct heating of the heating element 2, and the remainder of the heating element 2 is forced to be completely embedded in the support 3.

- As a result, a small part of the spirally wound heating element 2
The supporting body 3 is exposed at appropriate intervals depending on the winding pitch.

The refractory according to the present invention is a spirally wound Fe-Al-
Since most of the heating element made of Cr-based metal wire is buried and a part of its outer peripheral surface is exposed, Fe
-Even if there is a decrease in mechanical strength at high temperatures, which is a characteristic of the Al-Cr system, there will be no damage to the heating element, which was experienced in the past due to the support of the heating element, and it will be safe and reliable. It can support a heating element.

In addition, by supporting the heating element buried, there is less sudden temperature change in the heating element when the temperature rises, and in addition, when the temperature falls,
Since the refractory is less susceptible to sudden temperature changes due to the effects of high heat, there is no sudden expansion and contraction of the heating element, and the surface oxide film is less likely to peel off.

Therefore, Fe-Al-Cr-based AI consumption is low, and there is no change in electrical resistance, resulting in stable output and long-term use.

Furthermore, in the present invention, the spirally wound heating element is
It is buried in the refractory with a part of its outer peripheral surface exposed, and this exposed part absorbs the deformation caused by the expansion and contraction of the heating element when the temperature drops and rises. Damage to objects can be avoided.

According to experiments conducted by the inventor of the present invention, the following results were obtained regarding the change in electrical resistance of the heating element in the refractory according to the present invention and the completely exposed type heating element with respect to elapsed time.

[Brief explanation of drawings]

Figure 1 is a front view showing the buried state of the heating element, Figure 2 is the
It is a sectional view seen from arrow II-II in the figure. In the diagram: 1... refractory, 2... heating element,
3...Support, 5...Part of the heating element.

Claims (1)

[Scope of utility model registration request] A part of the outer peripheral surface of the heating element made of a spirally wound Fe-Al-Cr metal wire is exposed so as to enable direct heating to the heated part, and the rest of the heating element is covered with refractory material. A refractory in which a heating element is embedded in a support made of.