Advantages of Single Screw Extruder

     Advantages of Single Screw Extruder

The significant advantages the Single Screw Extruder with barrier according to the present invention has the advantage that the pressure build-up capability is improved. Compared to the known Twin Screw Extruder it is not necessary any more to build up a very high pressure in the so-called feed zone as to enable a predetermined lower pressure at the end of thegravimetric feeder With the according to the present invention it is possible to substantially reduce the pressure between the feed zone and the melting zone. This in turn results in a reduction of wear of the gear pump in the transition area between the feed zone and the melting zone since it is operated with lower pressures.

(1)In a preferred embodiment the barrel comprises several grooves being equally spaced apart in circumferential direction which grooves extend preferably parallel to the longitudinal axis of the barrel. This has the advantage that the process of matching the grooves is simplified compared with the groove helically arranged.

(2)Due to the pressure reduction in the area of the feed zone it does not have to be constructed any more as complicated as in prior solutions and does not have to be provided with cooling means and a “heat separation” towards the heated melting zone. Advantageously, the feed zone and the melting zone may therefore be formed individually.

(3)In a further preferred embodiment the width and/or the depth of the groove varies in a longitudinal direction, preferably the grooves depth decreases towards the downstream end of the melting zone section, preferably to zero.

This has the advantage sheet production extruderthat the groove extends continuously without Single Screw Extruderany break along the feed zone and melting zone thereby further improving the output and the pressure build-up. 

In a further preferred embodiment of the invention at least one groove is provided also in the barrel inner surface (innerwall) in the area of the feed zone section, the groove extending parallel or helically relative to the longitudinal axis. Preferably, the groove in the area of the feed zone section leads into the groove in the area of the melting zone without transition. Preferably both grooves have the same lead angle.

What are the key differences between PVC and PE pipes and fittings?

      What are differences between PVC and PE pipes ?

PE  benefits

• Chemically inert, no off gassing or leaching.
• Flexible, can be pulled to around corners to eliminate fittings.  This give a better water flow, and saves time and money.
• Can freeze without bursting
• Is rated to last at least 200 years
• No glue to add poisonous vapors or soldering to reduce risk of fire.

Negatives

• Pipe and fittings are reduced in diameter, may need to up size for good flow.
• Pipe has no rigidity.  Must be supported it's entire length.
• Need special tools to install.

PVC and CPVC "for hot" benefits

• Any can do it, all you need is a cutter to assemble.
• Very cheap and you can get it anywhere.
• PVC is full bore, but only for cold water.

Negatives

• All sorts of leaching flavors and chemicals into water.
• Rated for 20 years, this is an over statement.
• Glue needs to cure for 24 hours before charging with pressure.  Most do not do this, but that is what is instructed.
• Freezes and bursts quite quickly.
• Some plumbers will not attach to it for it has a high failure rate.

How to Make Plastic Pipes

             How to Make Plastic Pipes

Plastic has largely become the material of choice for pipes. Its flexibility, ease of bonding, lighter weight than iron and steel and lower cost than copper has made it a common choice. Pipe is generally produced by an extrusion process. Although this process may vary in actual operating conditions (temperatures, pressures, extrusion rate) based on the type of plastic used, diameter of pipe and wall thickness, the fundamental process of extrusion is reasonably consistent throughout the industry. 

• Add the thermoplastic resin to the feed hopper. Although this can be done manually, it is generally transferred to the hopper via a vacuum feeder due to the steady state nature of the process. This helps minimize the chance of running out of resin during the process.
• Turn on machine screw and barrel heaters per specific resin requirements. The heaters add heat to the plastic while it is in the barrel to melt the plastic. The rotating screw adds shear heat to the plastic for melting as well as building up the pressure to force the plastic through the die.
• Extrude plastic through the die. The die is designed and built based on the dimensions desired in the pipe and the shrink rate of the type of plastic being used.

• Cut the pipe at the desired length. The extruded pipe will exit the die onto a roller system to allow the pipe to cool without deforming under its own weight. Once it has passed a certain length, it will trip a sensor (electric eye) triggering a cutting operation on the pipe. The cut is made by a cutter that moves forward at the rate of pipe extrusion to offset the motion of the pipe moving forward so that the end of the pipe will remain perpendicular to the pipe wall after it is cut.
• Continue the process in a steady-state environment until the desired quantity of plastic is produced.

Extrusion System For Plastics Extrusion Machine

Extrusion system consists of screw and barrel, Hopper, die, and die, plastics by squeezing the system plastics melt evenly, and, in the process of establishing, under pressure from continuous by screw extruder.

1, screw: is the most important parts of extruder, it is directly related to applications and productivity of extruders, made from high-strength corrosion-resistant alloy steel.

2, barrel: is a metal cylinder, generally with higher heat resistance, compressive strength, strong wear-resistant, corrosion-resistant alloy steel composite pipe made of or lined with alloy steel. Barrel and screw fit, realize the plastic pieces, softening, melting and plasticizing, vent and compaction, and uniform conveyor rubber molding system. Barrel length is 15~30 times the diameter, so that the plastic is fully heated and fully plastic into principles.

3, Hopper: hopper with cut-off device at the bottom, so you can adjust and cut off the flow, side of the hopper with sight and calibration of metering devices.

4, die and mold: head made of alloy steel and carbon steel coat, and head is equipped with mold, heads are used to rotate the plastic melts into parallel straight line movement, steady import model Kit, and endows plastics with the necessary pressure. Plastic plastic in the barrel of the compaction, porous plate along a certain flow through head neck into head mold, die mandrel set appropriate, formation cross section decreases of the annular space, plastic melt around the wire to form a continuous solid tube coating. In the guarantees head plastic reasonable channel, elimination of accumulated plastic corner, often placed with split sleeves, for elimination of plastic extrusion pressure fluctuations, there is set of grading rings. Head is also equipped with mould correction and adjustment device, easy to adjust and align core and mould sleeve of concentricity.