Precision glass pressings with no mould flash - made from heated blank in die contg upper and lower moving punches

摘要

Mfr. of precision pressings of glass with a vol. below 5cm3 and with dimensional- and wt. -tolerances below 5%, in which a glass blank, pref. a pellet or rod, is conveyed by a feeder, esp. a screw feeder, to the die, the feeder contg. a heater for the blanks; the die consists of a die-bush with moving upper and lower punches, the upper punch contg. core rod(s) for making hole(s) or indentation(s) in the glass pressing; the movements of the feeder and the die are synchronised and the velosity of the glass is below 104 poise durin the die set to keep it at the required temp. Accurate glass pressings are obtd. with no flash, so that tno extra operations are required after pressing, i.e. the pressing produces finished parts.