GB935844A - Methods and apparatus for controlling the characteristics of heat softened materials - Google Patents

Abstract

935,844. Measuring temperature electrically. OWENS-CORNING FIBERGLAS CORPOR. ATION. June 8, 1960 [June 15, 1959], No. 20168/60. Class 40 (1). [Also in Group XXIII] Variations in temperature dependent characteristics of heat-softened mineral material flowing in a stream are sensed by flowing a heat-absorbing fluid to and from a region in heat transferring relation to the stream and continuously absorbing heat from the stream into the fluid, transferring heat from the fluid to sensing means which respond to variations in the amount of heat absorbed by the fluid from the stream and indicating the response of the sensing means as an indication of variation in temperature dependent characteristics of the material. In the form shown in Fig. 1, fibres 27 are drawn from tips 20 fed by glass in a feeder 10 heated by passage of a current between terminals 14. Heat-absorbing fins 30 of a good heat-conducting metal are supported from a pipe 32 through which cooling fluid is circulated. Thermistors 36, 38 sense the temperature of the fluid both entering and leaving and are connected in a bridge circuit, the amount of unbalance of which, as indicated on the meter 43, is a measure of the temperature difference. This difference, with a constant fluid flow, is a measure of the heat absorbed by the fins 30 and hence of the temperature of the glass emerging from the tips 20. Absorption of heat by the fins 30 directly from the feeder 10 can be prevented by a plate parallel to and slightly spaced from the bottom of the feeder, provided with holes through which the tips 20 project and attached to a separate pipe-carrying cooling fluid. A number of thermistors may be provided at different points along the pipe 32 and used to measure the heat absorbed by different groups of fins 30. The glass feeder may be provided with a number of terminals along its length, the heating current being fed thereto in such a way as to correct for any non-uniformity. In Fig. 7, alternate cooling fins 84 between the tips 69b are connected to a tube 32b with thermistors 92, 93, 94, 95, groups of intervening fins being formed into units 86, 87, 88, through which separate streams of cooling fluid circulate, the temperatures or rates of flow being adjusted to adjust their heat absorption to maintain temperature uniformity. Another arrangement, in which the tips are arranged in two longitudinal rows only, has longitudinal pipes carrying cooling fluid which themselves provide the heat absorption and are sufficiently flexible to be adjusted relatively to particular groups of tips to adjust the heat absorption from them. Another arrangement provides for adjustment of the adsorption of individual cooling fins by mounting the fins to be each vertically adjustable in a dovetail slide carried on the pipe for the cooling fluid. Fig. 8 shows an arrangement for compensating for any distortion of the bottom of the feeder. The cooling fins 118 between the tips 100 are attached to pipes 94, 95 connected by a flexible pipe 108. Each pipe 94, 95 is supported on a fulcrum 102 and a link 114 or 116 attached to a loop 112 on the feeder. In a similar form a downwards force is applied to each pipe 94, 95, outwardly of its fulcrum and upward movement of its inner end is limited by a distance piece abutting the bottom of the feeder. The downward force may be applied by springs or weights, hydraulically or electromagnetically. Fig. 15 shows an arrangement for indicating the characteristics of a stream 178 issuing from an orifice 176, in a forehearth, for example, for delivering to apparatus for further processing. Cooling liquid passes through an annular vessel 182 carried on an insulating support 198 to surround the stream. The inlet and outlet pipes are provided with thermistors connected in a bridge as in Fig. 1.