Extruder pin-barrel

The massive quadroplex extmsion head is designed to handle four extmders with two each 10 in. (250 mm) and 8 in. (200 mm) pin-barrel extruders. 

A further development is the combination of the pin barrel extruder system with that of the Transfermix (see under EXTRUDERS, MIXERS). The combined system is known as Pinconvert and is available with or without vacuum extraction. 

Figure 3.31 Photograph of the unwrapped channel contents of a pin barrel extruder.

Laake, H. J. and Rabiger, N., Temperature Development in a Rubber Processing Pin Barrel Extruder, Kunststoffe, 78, pp. 833-837, Sept. 1988. 

The factory system based on internal mixers, screw extruders, calenders, and vulcanization presses has remained basically unchanged in the past half-century. Internal mixers have had major improvements, e.g., intermeshing rotors proposed by Francis Shaw and Company [C16] and Werner and Pfleiderer [L3], and variable intermeshing clearance rotors [PI] proposed by Pomini-Farrel SpA. Sophisticated computer control systems have been introduced. The early single hot-feed extruders have been replaced by cold-feed extruders with increasingly sophisticated design including pin barrel extruders [G7, H12, H13, M18, W16] as well as complex control systems. 

Until the 1980s, most simulations of polymer operations related to thermoplastics problems. The special processing machinery of the rubber industry had receive little attention. It is only in the late 1980s that realistic simulations appeared for internal mixers [CIO, Cll, H20, H21, K6-8, W19] and pin barrel extruders [B31, B32, B34, K22]. These have used primarily lubrication theory-based simulations. 

FIGURE 24 Flow marker experiments for pin barrel extruder of Yabushita et al. [Yl]. (a) Cross sections of vulcanized rubber strip removed from the area between the first and second grooves (extruder run without pin application). Operating conditions Tb = 80°C, = 80°C, N = 10min" ... 

The flow in pin barrel extruders has been simulated in recent years by Brzoskowski et al [B31, B32, B34] using hydrodynamic lubrication theory methods for a Newtonian fluid. Basically they embed a coordinate system in... 

In fact, in several extruders, dispersed solids melting (DS) is more likely to occur than contiguous solids melting. This is particularly true of extruders that do not feature a continuous, uninterrupted channel for material flow. Examples are twin screw extruders and pin barrel extruders. 

If the polymer is not available as reactor powder and needs pellet grinding, the costs will probably be uneconomic. If reactor powder is used, there may be a risk of its availability being discontinued as happened with PP reactor powder used in an experimental pin barrelled extruder. In this case, a flood fed 20 mm extruder with four pins of 3 mm diameter mounted radially at 90° to each other and at 2 D intervals, passed through slots in the screw flights [6]. Good dispersion was achieved with PP powder with 20 wt% chalk filler blends, whereas dispersions were poor when PP granules were used. Soon afterwards, the reactor producing the PP powder was closed down, and at the time there was no alternative supplier. However, in the production of colour masterbatches, linear low-density polyethylene reactor powder is sometimes used. 

Mixing processes in different extruders were evaluated for the continuous incorporation of liquids into rabber compounds. A 60 mm Transfermix extruder and a 90 mm pin barrel extruder both produced good results. The Transfermix extruder seemed to be more promising for this application because when this was used, up to 8 wt% of liquid could be incorporated into the compounds in... 

Vacuum extruders can be single- or multi-vented. Versions also exist which have an added pin barrel processing extension. 

Co-Kneader (Ko-Kneader) having Reciprocating Scre v and Pin Barrel -Parrel Continuous Mixer -List Continuous Mixer -Ring Extruder. 

A numerical study of the 3D polymer melt flow in a intermeshing counter-rotating twin screw extruder and in a intermeshing counter- rotating twin screw extruder with pin-barrel have been carried out. We get the pressure, viscosity and shear rate field distribution of melt conveying zone. 

A Uniroyal patent originated the principle of using pins protruding into the extruder barrel to disrupt the laminar flow of compound, and this principle was further developed by Troester in their QSM (cross-flow mixing) machines. The protrusion of pins into the barrel necessitated a modification to the screw design to accommodate them. Many papers can be found in the literature dealing with this type of pin extruder. 

Extruders with retractable pins (hydraulically inserted or withdrawn) can be used to vary the degree of mixing that takes place as the compound travels the length of the barrel. 

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