Piston-type extrusion presses

A press consists of two main parts, the driving mechanism and the press head, detailed in Fig. 5.13. The press head contains the mould channel which corresponds to the cylinder in the piston engine analogy. At the rear portion of the press head is a feeding hopper and entrance through which the briquetting material is fed to the mould channel. The material is pushed forward by the stroke of the piston (press stamp) and compacted in a hammer- 

Modem piston-type extrusion presses contain multiple stamps and moulds of twin, triple or double-twin construction [7]. At an operating speed of 100 rpm, a triple-type press produces 10.5 tons/h (9.5 Mg/h) and a double-twin type press 16 tons/h (14.5 Mg/h) of lignite briquets. Power requirements are in the range 22 to 35 kW-h/ton (30 to 47.5 hp-h/ton) depending on the feed properties. 

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Piston-type extrusion presses are described in Section 2.3.1. 

Fig. 5.12. Schematic diagram of the piston-type extrusion briquetting press [7].

Fig. 5.13. Diagram of the head section of a piston-type extrusion briquetting press [17]-...

Extrusion presses of the piston type, roll type, and screw or auger type are in use. 

Contrary to inner gliding surfaces, cutting laminations are usually a-ligned in the direction of extrusion. As they are created exclusively in the die or pressure head, these cutting laminations can be found with ill types of extruders, i.e. with piston extrusion presses as well as auger extrusion units. 

Flow laminations, laminations caused by inner gliding surfaces, and cutting laminations, all can be distinguished to varying degrees in the extrusion of plastic bodies, independent of the extrusion method employed, e.g. piston extrusion presses, single-shaft extruders, twin-shaft extrusion machines or rotory-type extruders. 

Basic types of extruders include both screw extruders such as axial endplate, radial screen, and basket designs, as well as pelletization equipment described above, such as rotary cylinder or gear and ram or piston extruders (Fig. 21-136). See Newton [Powder Technology ana Pharm. Processes, Chulia et al. (eds.), Elsevier, 1994, p. 391]> Pietsch (Size Enlargement by Ag omeraUon, Wiley, 1992), and Benbow and Bridgwater (Paste Flow and Extrusion, Oxford University Press, 1993). 

In order to render possible casting of the molten lead into the container, a lifting cylinder a with piston b for the lifting of the crosshead c is arranged on top of the press. The nuts d are provided with bayonet-type threads. When changing tools, the crosshead / may be lifted with the help of the clamps e. Casting of the liquid lead is followed by an interval of five to ten minutes to allow for the solidification of the metal. The extrusion temperature is about 210 °C. 

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