GB959391A - Thermometer manufacturer - Google Patents

Abstract

<PICT:0959391/C1/1> <PICT:0959391/C1/2> Apparatus for sealing the bulb and forming the topping chamber of a thermometer comprises means for clamping the centre part of a thermometer case in a horizontal position and rotating it about its longitudinal axis when so clamped, and means for heating regions of the case on opposite sides of the clamping means. The thermometer case is held in a three-jaw chuck 3, supported on a casting 2 from the main base-plate 1 and rotated from a motor 7 through belt 4 and pulleys 5, 6. Brackets 8 at each end of the base-plate 1 support parallel tubular tracks 9 which pass through the casting 2 and on which are mounted carriages 10, 11. Carriage 10 supports a wide burner 12 for heating a band of glass approximately 1/2 inch wide for blowing up the topping chamber and chamber 11 a pin fire burner 13 for sealing off the bulb, both burners being supported by knuckle joints 14, 15. The bulb is sealed first by burner 13 moved into position opposite the desired marked point on the case by a handle 16 moving the support 17 into engagement with a spring-loaded plunger 18 to disengage a friction clutch 18a on one track 9 to allow sliding along the track 9. The case is then normally annealed before forming the topping chamber by burner 12 after filling the bulb with mercury or spirit, which is heated to expand the filling medium to compress the air trapped in the bore and thereby form a bubble in the bore, the bubble being then extended by hand operation by tweezers.