Basic knowledge of the extruder
A.The composition of the extruder
It consists of extrusion system, transmission system, and heating and cooling system.
1 extrusion system
The extrusion system includes a screw, barrel, hopper, nose and mold, plastic plasticized by extrusion system to form a homogeneous melt, and in this process created by extrusion, the extrusion head of the screw continuity.
(1) Screw; the main components of the extruder, it is directly related to the the extrusion range of applications and productivity, from high-strength corrosion-resistant alloy steel.
(2) barrel; is a metal cylinder, generally with heat-resistant, high compressive strength, rugged wear-resistant, corrosion-resistant alloy steel or alloy steel inner shirt made of composite steel. Barrel and screw extrusion crushing, softening, melting, plastics, exhaust and extrusion, continuous and uniform transport plastic material to the molding system, with.
(3) hopper; the bottom of the hopper is equipped with a cut-out device, in order to adjust and cut off the feed stream, the side of the hopper is equipped with, as the hole and calibration of the measuring device.
(4) head and mold; nose alloy steel inner sleeve and carbon steel jacket, the head interior molding mold, the role of the head of the rotation of the plastic melt into a parallel linear motion, uniform and stable import die sets, and give the plastic with the necessary molding pressure, plastic the machine barrel plastics compaction, porous filter plate along certain flow channel through the head neck and into the head mold, the mold core die sets appropriate coordination, the formation of cross-section with decreasing annular space, the plastic melt to form a continuous dense tubular cladding around the core wire, plastic head in order to ensure reasonable channel to eliminate the accumulation of plastic of the dead, often placed a shunt sleeve for eliminate plastic extrusion pressure fluctuations, but also set the grading rings. The machine head is also equipped with mold calibration and adjustment means to facilitate adjustment and correction of the mandrel and the die sets concentricity.
In accordance with the the head material flow direction and the angle of the center line of the screw, extruder head into the bevel head (angle 120 ¡ã) and right-angle head. The head shell is screw fixed to the machine body, head mold mold core sit and nut fixed to the front of the head into the line port, mold core seat is equipped with core, the mold core and the mold core seat SMIC hole for the core wire; installed in front of the nose and the pressure ring for pressure equalization; extruded forming part of the seat by the die sets and die sets, die sets the position by the bolt through the support to adjusted to adjust the relative position of the mandrel die sets, to squeeze easy to adjust the uniformity of the thickness of the cladding layer. The head is equipped with external heating means and the temperature measuring device.
2. Transmission system
The role of the drive train is the drive screw, the required torque and speed of the supply screw in the extrusion process, usually by a motor, reducer and bearings.
Heating and cooling devices
Heating and cooling is a necessary condition for the extruder discharging process can be performed.
(1) extruder is typically electrically Heated divided into resistive heating and induction heating, the heater chip mounted on the body, the mold is pressed more than the extruder machine neck, each part of the handpiece. Heating means plastic barrel by external heating, so that heating up, in order to achieve the desired temperature of the process operation.
(2) The cooling device is set in order to ensure squeeze the plastic is in the temperature range of the process requirements. Specifically, in order to eliminate excess heat generated by the rotation of the screw shear friction to avoid overheating the plastic decomposition, scorch or stereotypes difficulties.
4, the use of the extruder Note
Extruded confidential forward operation, avoid rewind.
2 avoid fasting operation, must be heat engine feeding operation, it can avoid the sticky bar (axle) phenomenon occurs.
Extruder feed inlet air vent allowed to enter the impurities such as iron, so as not to cause an accident, affecting production.
Safe use of electricity, ground wire.
Machine running import materials and export materials, belts, gears and other rotating parts touch.
The machine should be preceded by injection lubricating oil, so as to avoid damage to the machine.
The basic knowledge of the extruder;
An operator must be familiar with the procedures, qualified by the Security exam, wear protective equipment, shall be allowed to operate the equipment.
2 power switch on, check the electrical thermal control is sensitive and reliable thermocouple indicates that the temperature is correct, problems ask the service technician to exclude non-operating workers tamper with.
3 car should check the host gearbox, traction stepless transmission the closing line stepless gearbox lubrication is normal, the fan is properly ventilated.
Pay attention to paragraphs 4 before driving the heating temperature, meets the technological requirements of the actual temperature, holding time must be adequate insulation, the initial heating time of not less than 3 hours.
5 shall not be bad in the plasticizing charred aging extrusion, to prevent accidents and found the problem immediately try to exclude.
6 speed from low to high, add the normal speed, non-high-speed from the car, observe the instrument indicated on the current value and the temperature is normal, in case the current is too large, causing the heater had burned.
7 lift spools, we should pay attention to lift the limit position must not be too high or too low, the electrical limit shall not exceed the limit.
8 feeding into the hopper, note that the metal was not allowed to enter and poke plastic pressed into the screw with a screwdriver or metal rod is strictly prohibited.
Around 9 Checking the dry test machine shall be equipped with rubber insulation plate, or are not allowed to drive.
10 before driving should check the various parts of the ground is good, grounding resistance should be measured regularly, shall not exceed 4 ohms; equipment noise and other anomalies, and then fix the problem if any.
11 No hand to touch the dry parts of the test machine of high-voltage electrical appliances, electrical wiring or grounding wire.
12 cores on the water against car.
13 did not stop before the prohibition to touch the insulated core wire connectors and exposed part; cores in the high-voltage discharge to first take measures, and repair.
14 car parking commanded by skilled workers to avoid the risk of misuse.
15 with a softening equipment, plastic machine, the operator can not be moved to adjust the electrical and mechanical equipment; hand can not touch the wire, the conductance wheel, copper catheter site.
The end of the 16 car, turn off all the power and water supply, gas supply, the operating handle back to its locked position, and make shift diary records.
