SU695158A1 - Oven for drawing fibre from high-melting class - Google Patents

Description

The invention relates to the industrial construction and building materials, in particular, to devices for producing optical glass, namely

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For the fabrication of refractory glass fibers, for example, of quartz glass, used in communication lines of optical communication, as well as in optoelectronics and computer technology. A furnace for drawing fibers from refractory glass, including a body, an oxide heater installed in the casing, is known from high-refractory material, and electrodes connected to the heater. In this case, the furnace contains one tubular oxide heater installed along the fiber drawing axis, and the electrodes are pressed against the ends of the heater.

A known furnace for drawing fiber from a refractory material, comprising a chamber with a high-temperature material in the form of a body of revolution with a hole along the axis, current-conducting electrodes with double-sided connection and a cooler around the heater.

In such furnaces, the temperature on the working radiating surface of the heater can reach 2000 ° C, which is an advantage. However, it is impossible to get a higher working temperature due to plastic deformation of the heater, under the influence of high temperature and axial pressure on the heater, caused by pressing the electrodes. The most significant drawback of the known furnaces is the impossibility of controlling the temperature gradient along the height of the heat and gas space due to the rigid design of the heater, which determines this gradient. In the meantime, a different temperature gradient along the height of the hot space is required to draw the fiber from blanks of different diameters. Even with a single billet diameter, a change in the temperature gradient is required depending on the structure and composition of the billet material. The purpose of the invention is to control the temperature gradient along the height of the hot space. This is achieved by the fact that furnaces for drawing fiber from refractory glass, comprising a housing, an oxide heater made of high refractory material, connected to electrodes, and coolers, located in a heater box, the latter made in the form of two hollow bodies with a flat working radiating surface mounted the ability to adjust the distance between them and rotate around the longitudinal axis from the drive, the heaters being located in the same plane parallel to each other on both sides of the working aperture, perpend The movement of fiberglass is well guided. In this case, oxide heaters can be made in the form of hollow parallelepipeds. In addition, the drive for adjusting the distance between the heaters and turning them around the longitudinal axes can be connected to the electrodes by means of insulating material bushings pressed against the electrodes by springs. Change the distance between the longitudinal axes of the window heaters and. turning the heaters around these axes causes a change in the distance between the heaters and the refrigeration devices, which causes a change in the heat exchange between the heating bodies and these devices. This leads to the redistribution of the resistance of the heater material in certain areas, current density and temperature on the working radiating surfaces of the heaters. A similar effect is also achieved by changing the cooling intensity of refrigeration devices. | This achieves the regulation of the temperature gradient along the height of the flame space. Further, a change in the distance between the longitudinal axes of the heaters and their rotation around the axes leads to a change in the distance of the working radiating surfaces of the heaters to the preform for stretching the thread. This changes the volume of the flame space, the specific amount of heat per unit volume, and thus the temperature gradient in this space. Figure 1 - shows a vertical section of the proposed furnace; in Fig.2 a section aa in Fig.1; on fig.Z - section bb in figure 2. The furnace includes a housing 1 having a lining 2 of refractory material in which oxide heaters 3 are installed, made of stabilized zirconia. These heaters have the form of hollow rectangular parallelepipeds with through holes at the ends. The longitudinal axis of the heaters 3, parallel to each other and lie in the same horizontal plane. Quartz glass preform 4 and fiber 5 to be drawn are located on a vertical axis. Platinum electrodes 7 are pressed to the ends of the heaters 3 by the alumina bushes 6. The bushes are mounted in the rotary axles 8 and the drive for adjusting the distance between the heaters 3 and turning them around the longitudinal axes. The clamping of the sleeves 6 and the electrodes 7 is provided by springs 9. The adjustment drive between the heaters 3 and their rotation around the longitudinal axes consists of a screw 10. connected by means of vertical posts II having nuts 12 to the trunks 8. Between the case 1 and heaters 3 installed cooling devices 13, made in the form of hollow metal containers with nozzles for supplying and discharging water. Inside the heaters 3 for the period of pre-heating there is a heater 14, made in the form of an alundum rod with a spiral made of a heat-resistant alloy.

A furnace for drawing fiber from refractory glass works as follows.

Heater 14 is introduced into the internal cavity of one of the heaters 3 and the heater 3 is preheated to. Then, an alternating current of industrial frequency is supplied to this heater. At the beginning of the self-heating of the heater 3, the heater 14 is removed ..

The second heater 3 subjects it to preheating from per95158. 6

heater 3, and then also turn on the power circuit.

During the operation of the furnace, a billet .4 is fed into the heating space and fiber 5 is pulled out of the working hole 15.

Rotating the screw 10 and turning the trunnion 8, as well as changing the cooling intensity of the heaters 3 with refrigerating devices 13, provide an individual selection of the optimum temperature gradient along the height 15 of the hot space.

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Claims (1)

Rotating the screw 10 and turning the caps 10 fy 8, as well as changing the cooling intensity of the heaters 3 by the refrigerating devices 13, provide an individual selection of the optimal temperature gradient along the height of the high-altitude space. φΐΗ.1 Water , r £ I —I 4 g h Yg FIG. 2 695158