Piston extruder

Alumina samples for investigation were prepared from aluminum hydroxide (Condea, type DISPERAL). A batch of aluminum hydroxide was kneaded either with water dematerialized solution of HNO3 (1%) or with water solution of cellulose derived product (commercial name CULMINAL), extruded with using of piston extruder, dried for 24 h at room temperature, then for 24 at 110 C and calcined for 4 h at 550, 650, 750, 800 or 850 "C). Obtained samples of alumina extrudates are described as DN (aluminum hydroxide "Disperal"... 

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). 

The elaboration of cordierite tubular supports is described in Fig. 5.9. The values correspond to 3 kg paste preparation and shaping with a laboratory piston extruder. 

The EFF machines utilize a 3-axis gantry with a piston extruder mounted on the z-axis. Extruder motions are driven by stepper motors and are indexed with a 4-axis motion control card which drives the x-axis, y-axis, z-axis, and one proportional axis. The 3D drawing of the desired component is converted to indexer code in an AutoCAD environment using proprietary ACR subroutines. During fabrication the extrusion piston is indexed at a rate proportional to movement on the x-y planes. 

Not all ceramic compounds are put through single-screw and twin-screw extruders. If the idea is to achieve very high extrusion pressures, minimal contamination, short series, etc., an intermittent piston extruder can be the machine of choice. 

In Piston extruders , Fritz Spiessberger and I try to explain then-function, design, benefits and drawbacks. 

The history of extrusion can be traced back to 1619 when the EngUshman John Etherington built a hand-operated piston extruder, with which bricks were produced. After the introduction in England in 1623 of the Statute of Monopolies , which governed the protection of inventions, a patent was granted to him for his brick machine. Hence the piston extruder can be considered the earliest extrusion machine. Initially, however, this did not gain acceptance. 

Fig. 1 Single-acting piston extruder, the so-called running-out machine or stupids , from 1810).

Fig. 2 Piston extruder with hinged extrusion barrel, circa 1870...

Fig. 3 Double-acting piston extruder with preceding pug mill and roller mill, Clayton, 1862...

Vertically-Operating piston extruders for the shaping of larger pipes were introduced around 1870. The first versions of these extruders were of such design that the piston moved inside the material-filled barrel from bottom to top with the aid of a spindle. However, this method was soon... 

Fig. 4 Vertical piston extruder with two rotating barrels, around 1880...

In the 1960s Messrs. Uniceram SA of Marseille, France, built a hydraulically-driven piston extruder for the stiff extrusion of structural clay products, combined with a de-airing double-shaft mixer, was operated as a combined de-airing extrusion unit (Fig. 5). On the whole however the piston extruder has been of relatively little importance in comparison to the auger extruder within the field of structural ceramics. 

Fig. 5 Combined de-airing extrusion unit with de-airing double-shaft mixer and piston extruder, built by Messrs. Uniceram, Marseille, about 1960...

Heath Company of Plymouth, Ohio, in 1919 for a de-airing machine, which enabled the clay to be de-aired even twice. This was in fact a double piston extruder followed by a mixer (Fig. 44). 

Hostenherg invents and builds a piston extruder in St. Petersburg for the production of drainpipes... 

Gebr. Sachsenberg in Rosslau/Elbe (Germany) build the first expression rolls machine in Germany Henry Clayton introduces a double-acting piston extruder at the London World Exhibition De Wolfe builds an extruder in USA for cable sheathing Lipowitz carries out first trials for heating the clay with a double-walled extrusion barrel... 

Hydraulically-operated de-airing piston extruder for stiff extrusion by Uniceram, Marseille, France... 

It was in 1619 that John Etherington built the first hand-operated piston extruder for the extrusion of bricks. 

This was followed by numerous different designs including doubleacting piston extruders reference is made in this coimection to flie details and illustrations under chapter 5. 

Piston extruders were, and still are, employed not only for the extrusion of ceramic bodies but also find application in many branches of industry for the shaping of plastic materials, or for bodies which have been plasticized by the tempering process. 

In 1810 Joseph Bramah used the first hydraulically-operated piston extruder for the shaping of lead slabs to produce pipes. 

Piston extruders are used in the foodstuffs industry, notably in the production of pasta, and are also employed for the shaping of aluminium profiles, wrought copper alloys and steel, for the extrusion and de-watering of sewage sludge, for the extrusion of hard metal, graphite, coal, plastics, etc. 

Focus in the following will be on the description of hydraulic piston extruders as employed in the ceramic industry and for the extrusion of hard metal, since the application in both cases is very similar and several interesting solutions have evolved for the shaping of hard metal with the use of piston extruders. 

Column extrusion by piston extruders is to be understood as a discontinuous shaping or extrusion process in which a plastic body is pushed through a die or matrice by a piston, whereby the geometry of the die determines the extruded profile. 

Piston extruders available these days for use in the ceramic industry can be classified into types of construction according to the following criteria ... 

The essential components of a tiltable piston extruder as generally applied in the ceramic industry nowadays can be seen in Fig. 2. 

An example a piston extruder is equipped with say two exchangeable receivers of 250 and 350 mm in diameter. The pressure of the system is say 280 bar and the diameter of the piston is say 200 mm, which would correspond to a press force of 880 kN. 

The type of base frame is determined by the design of the piston extruder. The loads exerted on the base frame are mainly of a static nature and are governed by the weight of the components, especially that of the hydraulic cylinder and that of the receiver, moreover by the position of the press frame with the resulting difference in load situations for the base frame and foundation. 

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