The extrusion head of PE pipe equipment is an important part of the extrusion molding production line. Its function is to further compact and plasticize the plasticized melt, divert it into the annular cross-section flow channel, and cool it into a tube blank. There are three types of pipe extrusion dies: straight-through dies, right-angle dies (also called bending dies) and side dies (side dies). Among plastic pipes, PE pipes have the largest output and are the most widely used, of which hard PE pipes account for 75% and soft PE pipes account for 25%. The following is a further introduction to the PE pipe head.
1. Straight through the machine head
The axis of the mold coincides with the axis of the extruder, and has the advantages of simple structure, easy manufacture, low cost, and small material flow resistance. This type of head has some disadvantages, such as the difficulty in heating the mandrel, and the low strength of the pipe at the seam caused by the shunt bracket. When producing pipes with large outside diameters and sizes. It can be seen from the structure of the flow channel that the fluid has to go through several stages such as flow diversion, compression, flow stabilization, and shaping. When it passes through the mold, here, L is the length of the straight part of the mold, L2 is the length of the compression part, and L is the diversion cone part.
2. Right angle nose
The mandrel end of this structure is the support end. Since there is no splitter bracket, the melt from the head end enters the opposite side of the mandrel and pools, which may only create a seam line. In addition to pipes, the right-angle mold can also produce wire and cable products, which has the advantages of easy heating of the mandrel and is suitable for extruding pipes from PE pipe equipment with inner diameter forming method. However, there are also disadvantages such as complex structure, difficult mandrel design, high manufacturing cost, and large material flow resistance.
3. side nose
The material flow from the extruder first flows through a curved flow channel, then enters the side of the die, wraps around the mandrel and exits along the axis of the die. This design can not only make the extrusion direction of the pipe be at any angle with the extruder, but also be parallel to the screw axis of the extruder, which is suitable for high-speed extrusion of large-diameter pipes. However, the mold structure is complicated and the cost is high.
4. Other types of heads
Other types of pe pipe equipment heads include sieve plate extrusion heads, coating heads, coating heads, mandrel rotating heads, etc. The rotary mandrel head uses ordinary polymer particles, after plasticization and melting, a certain length of glass fiber is mixed online, so that the molten molecules and glass fiber are spirally oriented along the tube wall of the extruded tube, thereby producing a higher strength. Pipes meet the needs of engineering practice.
