Extruder head angle

Angle head (offset head, and crosshead). An extruder head so designed that the principal direction of the extrudate makes an angle with the (extended) axis of the screw. See also crosshead. 

An extruder die-box or head in the shape of a letter T used in wire covering. The rubber flow is thus at right angles to the direction of travel of the wire. 

These fabrics can be applied in the hand-built construction of hoses in a spiral form at an angle to the axis of the hose. The knitted fabric can also be produced directly onto the surface of the inner liner of a hose and subsequently be covered with the outer cover compound by a cross-head extruder. 

The BM extruder is almost always arranged in a horizontal attitude, so the first task for the parison head is to turn the melt flow stream through a right angle. This is basically difficult and undesirable but necessary to achieve in a way that meets the essential requirement for a constant flow rate at every point in the annular die gap. A second and related requirement is that the parison should carry as little evidence as... 

Polymer-melt travels from the extruder to the head through an adapter. The internal design of the adapter should be streamlined to allow smooth flow. Conical reductions should, thus, be made at a maximum angle of 30°. The adapter should be equipped with a heater band to prevent cooling of the melt and also alleviate the need for overheating the melt in the extruder. Melt viscosity is a strong function of the melt temperature. Extrusion rate (the volume of the resin extruded per unit time) varies with viscosity so any variation in melt viscosity will be reflected in the extrusion rate. It is important to preheat the adapter by using the heater band to prevent solidification of the initial melt on its interior surface, which can result in excessive pressure build up. 

---