GB588793A - Method of and apparatus for presizing glass tubing - Google Patents

Abstract

588,793. Sizing glass tubing. FORRESTER, H. J. C. (MacGregor Instrument Co.). March 7, 1945, No. 5668. [Class 56] Relates to a machine for making the internal and external diameters of cut lengths of glass tubing to predetermined sizes, the tubes then being used, for example, for hypodermic syringes, stop cocks, or flow meters. The machine comprises a disc 37 carrying four arbors 39 equally spaced around its periphery, the frame thus formed being counterbalanced and manually swingable as a whole about a shaft, not shown, to and from inoperative and operative positions. In the inoperative position, a cooled sized blank is removed from the appropriate arbor and a new blank B is positioned thereon, the inner end of the blank abutting against a shoulder 48 on the arbor. The disc is now rotated through a quarter turn and is swung into its operative position wherein the newly-positioned blank is subjected to a preliminary heating, the arbor carrying the previously-positioned blank now being at the second station at which the blank is further heated and sized internally and externally, whilst the third and fourth arbors, each carrying a blank which has been positioned still earlier, are at cooling stations. The preliminary heating is by means of a ribbon burner 52 and the arbor carrying the blank at this station is rotated by friction gear from an electric motor. At the sizing station the blank is acted on externally by three rollers 69 positively rotated in engagement therewith about inclined axes and carried by a carriage 61 clutchable to a constantly running endless chain, whereby the carriage moves from left to right across the machine and the rollers 69 traverse the blank. Oxy-gas burners carried by the carriage heat the blank under treatment and the blank is constantly pushed against the shoulder 49 by a pressure cap 63<1> carried by a second carriage which is pulled by a weight in the opposite direction to that of the carriage 61 to compensate for the decrease in the length of the blank due to the thickening of its walls in conforming internally to the diameter of the arbor and externally to the distance between the pressure rollers. The travel of the carriage 61 in its forward direction is automatically arrested by a stop and this mechanism is also used to cut off the supply of oxygen to the burners and to declutch the carriage from the driving chain. The carriage is manually restored to its left-hand position and manual means are provided to reclutch the carriage to the chain and to re-open the oxygen supply. Means are also provided to move the rollers 69 axially slightly when removing the arbor and blank from the sizing station and positioning the next arbor and blank therein.