Blowing tubes

An assortment of glass connectors for joining blowing tubes and for connecting blowing tubes to rubber stoppers is desirable. For blocking holes in stoppers short pieces of rod or closed tubing are useful... 

A holder for a blowing tube can be made out of wire. This fits round the operator s neck, and holds the mouthpiece near the mouth. It is useful when engaged in complex operations which require the use of both hands for a long time. 

This small device is shown in Figure 12,1. It is a small union, to which a rubber blowing tube can be connected, and inside which an... 

Fine capillary tubes may become blocked with water when blown into from the mouth it may be desirable to put a drying tube in the blowing tube or to blow with a rubber bulb. 

Two sets of stoppers are very useful, one set unbored and a second set with a single hole bored in them to carry blowing-tube connectors. A longer piece of glass tubing inserted into the hole will also form a very adequate handle when working small pieces of apparatus. 

FIG. 4.11. A lubber blow-tube witli saliva trap. 

FIG 4.15. Bench-top accessories (a) cork stoppers with and without blowing tubes and handles (b) rubber tube plug, or policeman (e) Ribber blow-tube witli plain mouthpiece (d) laboratory stand with two clamps. 

A 2 m length of 6 mm mbber tube, fitted with a mouthpiece at one end, will be required for blowing up the molten glass. If it is required, a drying-tube containing calcium chloride (granulated)can be inserted in the mbber blow-tube. 

The glassware is set up in a retort stand so that the clamp is at a convenient distance from the proposed working region. The tube to which the side-arm is to be attached should be, wherever possible, horizontal. A rubber blow-tube is connected to the glassware and all other openings are securely stoppered a trial blow into the mouthpiece, to find out whether there are any significant leaks, is always worth while. 

FIG. 8.18. Handlamp join showing the retort stand and blow tube. The stoppered tube is held in die left hand the handlamp is held in tlie right hand and moved round to heat all the join, (a) shows the join pulled slightly apait immediately after the ends are touched togetlier. 

Every effort should be made to ensure that there are no air leaks anywhere in the blow-tube, swivel or stoppers. The stoppers must be a good fit and unhkely to blow out. It is most annoying, when the glass is heated and ready to be blown up, to find that there is a leak, or that a stopper has fallen out. 

A suitable length of rubber blow-tube and some "police-men" (or rubber plugs). 

Extrusion blow molding consists basically of the extrusion of a predetermined length of parison (hollow tube of molten plastic) into a split die, which is then closed, sealing both ends of the parison. Compressed air is introduced (through a blowing tube) into the parison, which blows up to fit the internal contours of the mold. As the polymer surface meets the cold metal wall of the mold, it is cooled rapidly below Tg or Tm- When the product is dimensionally stable, the mold is opened, the product is ejected, a new parison is introduced, and the cycle is repeated. The process affords high production rates. 

A similar procedure exists for producing hollow discontinuous profiles. Tube Blowing RTM utilizes a preform with the textile component wrapped around a flexible blow tube. The preform is placed in a mold and internally pressurized to ensure a uniform draping at the tool wall. The resin is then injected into the preform with a pressure lower than the inner pressure (Figure 1.17) [58]. 

---