SU872919A1

SU872919A1 - Muffle electric furnace

Info

Publication number: SU872919A1
Application number: SU792778269A
Authority: SU
Inventors: Владимир Сергеевич Пьянков; Александр Александрович Русанов; Светлана Дмитриевна Уткина
Original assignee: Предприятие П/Я В-2679
Priority date: 1979-06-07
Filing date: 1979-06-07
Publication date: 1981-10-15

Description

(54) МУФЕЛЬНАЯ ЭЛЕКТРОПЕЧЬ(54) PURPOSE PURPOSE

II

Изобретение относитс к электротермии и может бь1ть использовано в различных област х народного хоз йства дл создани нагревательных устройств, в частности в машиностроении , металлургии, в исследователь ских лаборатори х.The invention relates to electrothermal and can be used in various areas of national economy for the creation of heating devices, in particular in mechanical engineering, metallurgy, in research laboratories.

Известна электропечь, содержаща кожух с огнеупорной футеровкой и нагреватель в виде проволоки, заформованной в футеровку 1.A known electric furnace comprising a casing with a refractory lining and a heater in the form of a wire molded into the lining 1.

Однако ввиду значительного различи коэффициентов термического расширени материалов проволоки и огнеупора такие нагревательные элементы в процессе работы при температурах выше 700°С растрескиваютс . Дл предотвра1дени растрескивани проволоку используют малых сечений и в форме спирали, чтобы усили , возникаюш ,ие при термическом расширении в проволоке не превышали прочности проволоки .However, due to the significant difference in the thermal expansion coefficients of the wire materials and refractories, such heating elements crack during the operation at temperatures above 700 ° C. To prevent cracking of the wire, small sections are used and in the form of a spiral, so that the forces that occur during thermal expansion in the wire do not exceed the strength of the wire.

Наиболее близкой по технической суш,ности к предлагаемой вл етс муфельна электропечь сопротивлени , содержаща кожух с теплоизол цией, муфель из огнеупорного волокнистого материала и спиральныйThe closest in technical sushi to the proposed is a muffle resistance electric furnace, containing a casing with thermal insulation, a muffle of refractory fibrous material and a spiral

нагреватель, витки которого утоплены в муфель 2.heater, the turns of which are recessed into the muffle 2.

Недостатком такой печи вл етс , то,что под действием высоких температур в процессе эксплуатации происходит растрескивание нитей керамического волокна нагревател ,The disadvantage of such a furnace is that under the action of high temperatures during operation, the cracking of the filaments of the ceramic fiber heater occurs,

5 витки спирали нагревател из-за недостаточного сцеплени с муфелем растрескиваютс , набегают друг на друга, что приводит к выпадению витков из муфел . Основной причиной выпадени витков цилиндрической5 turns of the heater coil, due to insufficient adhesion to the muffle, crack, fall on each other, which leads to the loss of turns of the muffle. The main reason for the loss of cylindrical turns

Q спирали из пазов муфеЛ вл етс расшатывание витков и сдвигание каждого витка вокруг оси спирали при нагреве и охлаждении . Вследствие -этого происходит «набегание витков, которые привод т к тому, что .при охлаждении диаметр одного из витковThe Q helix of the Muffle slots is the loosening of the coils and the displacement of each coil around the axis of the helix during heating and cooling. As a result, this leads to an "overflow of turns, which leads to the fact that during cooling, the diameter of one of the turns

15 (как правило, крайнего) становитс меньше диаметра муфел . Этот виток при нагреве уже не занимает свой паз в муфеле и провисает вплоть до замыкани с соседним витком.15 (usually the extreme) becomes smaller than the diameter of the muffle. This coil during heating no longer occupies its groove in the muffle and sags right up to the closure with the next coil.

20 Цель изобретени - повышение надежности и долговечности электропечи.20 The purpose of the invention is to increase the reliability and durability of an electric furnace.

Claims

The goal is achieved by the fact that a resistance muffle furnace, containing a casing with thermal insulation, a muffle of refractory fibrous material and a spiral heater, the coils of which are partially recessed into the muffle, the spiral heater is made in the form of a hexagonal or octahedral. FIG. 1 shows a muffle resistance electric furnace, longitudinal section; in fig. 2 - the same cross section. The muffle resistance furnace contains a casing 1 with thermal insulation 2, a muffle of refractory fibrous material 3 and a spiral heater 4. Spiral heater 4 is made in the form of a hexahedron or octahedron polyhedron, the tops of which are recessed in the refractory fibrous material 4. The electric furnace works in the following way. . When the heating is turned on, the heater expands. At the vertices of the polyhedron, the heater 4 is compensated, and this prevents the spiral heater 4 from loosening and rolling over each other and falling out of the muffle. The spiral heater should be made in the form of a hexagonal or octahedron, since with a smaller number of faces, the tops of the polyhedron become deeply embedded in the high-temperature fibrous material, which leads to local overheating and premature release of the heater. When the number of faces is more than eight tops of the spiral heater, they are insufficiently submerged deep and the electric furnace has the same drawbacks as the known muffle resistance furnace. Performing a spiral coil in the form of a polyhedron eliminates the rotation of the coils around the axis of the spiral. The elasticity of the fibrous material allows free extension of each rectilinear section of the coil in both directions, which eliminates the "running of coils. The use of a muffle electric resistance furnace increases the service life by 2.5 times, reduces the need for them with a wire wire twice, reduces the heating time of the furnace to 1-2 minutes. At the same time, there is no need to keep the oven turned on permanently, which leads to energy savings. Claims An electric muffle furnace comprising a thermally insulated jacket, a muffle of refractory fiber material and a spiral heater, the coils of which are partially recessed in the muffle, characterized in that, in order to increase the reliability and durability of the electric furnace, the spiral heater is made in the form of a six- or octagon . Sources of information taken into account in the examination of 1.Kuvakin VM and others. Heating elements with a spiral, pressed into ceramics. - “Electrotherms, 1976, vol. 8 (168).

2. The UK patent number 1350574, cl. H 5 H, 1970.