The main machine of Plastic Squeezer Machine is an extruder, which consists of an extrusion system, a drive system and a heating and cooling system.
Plastic Squeezer Machine's extrusion system
The extrusion system includes the screw, barrel, hopper, head, and mold. The plastic is plasticized into a uniform melt through the extrusion system and is continuously extruded from the head by the screw under the pressure established in this process.
1. Screw: is the most important part of the extruder, it is directly related to the scope of application and productivity of the extruder, made of high-strength corrosion-resistant alloy steel.
2. Barrel: a metal cylinder, generally made of heat-resistant, high pressure strength, strong wear-resistant, corrosion-resistant alloy steel or alloy steel lined with composite steel pipe. The barrel cooperates with the screw to realize the crushing, softening, melting, plasticizing, exhausting and compacting of the plastic, and continuously and evenly conveying the rubber to the molding system. Generally the length of the barrel is 15-30 times of its diameter, so that the plastic is fully heated and fully plasticized.
3. Hopper: The bottom of the hopper is equipped with a cut-off device for adjusting and cutting off the material flow, and the side of the hopper is equipped with a sight hole and a calibrated measuring device.
4. Head and mold: The head is composed of alloy steel inner sleeve and carbon steel outer sleeve, and the head is equipped with molding mold. The role of the head is to transform the rotating plastic melt into a parallel linear motion, which is evenly and smoothly introduced into the mold sleeve, and give the plastic the necessary molding pressure. The plastic is plasticized and compacted in the barrel of the machine and flows through the neck of the head through a certain flow path through the perforated filter plate into the head molding mold, and the mold core and mold sleeve are properly matched to form an annular gap with decreasing cross section, so that the plastic melt forms a continuous dense tubular cladding layer around the core line. In order to ensure that the plastic flow channel in the head is reasonable and to eliminate the dead angle of the accumulated plastic, there is often a diversion sleeve placed, and to eliminate the pressure fluctuation of plastic extrusion, there is also a pressure equalization ring set. The machine head is also equipped with a die calibration and adjustment device, which is convenient for adjusting and correcting the concentricity of the die core and die sleeve.
Plastic Squeezer Machine’s head
The extruder head is divided into angled head (120o angle) and right-angle head according to the angle between the head flow direction and the screw centerline. The housing of the head is bolted to the machine body. The die inside the head has a die core sitting and is fixed to the head inlet port with a nut. The front of the die core seat is equipped with a die core, and there are holes in the center of the die core and die core seat for passing the core wire. An equalizing ring is installed at the front of the head for equalizing the pressure. The extrusion forming part is composed of die sleeve seat and die sleeve, and the position of the die sleeve can be adjusted by bolts through support to adjust the relative position of the die sleeve to the die core, which is convenient to adjust the uniformity of the thickness of the extrusion layer. The outside of the head is equipped with heating device and temperature measuring device.
What makes the drive system work is the driving screw. The screw is supplied with the torque and speed required for the extrusion process, usually consisting of an electric motor, reducer and bearings.
Plastic Squeezer Machine's Plastic Extrusion Process
Plastic extrusion process Heating and cooling are necessary for the plastic extrusion process to work.
1. Nowadays, the extrusion machine is usually heated by electricity, which is divided into resistance heating and induction heating, and the heating sheet is installed in each part of the body, neck, and head of the machine. The heating device heats the plastic inside the barrel from the outside to warm it up to the temperature required for the process operation.
2. The cooling device is set up to ensure that the plastic is in the temperature range required for the process. Specifically, it is to exclude the excess heat generated by the shear friction of the rotating screw, in order to avoid the high temperature of the plastic decomposition, scorching or shaping difficulties. Barrel cooling is divided into two kinds of water-cooled and air-cooled, generally small and medium-sized extrusion machine using air-cooled more appropriate, large is more water-cooled or a combination of two forms of cooling; screw cooling is mainly used in the center of water-cooled, the purpose is to increase the rate of solid material delivery, stabilize the amount of rubber, while improving product quality; but the cooling at the hopper, one is to strengthen the role of solid material delivery, to prevent the plastic grain sticky blockage because of the heating The second is to ensure the normal work of the transmission part.