Important principles plastic granulator plastic particles extruder(1)
Published:2014-09-13 19:16:21    Text Size:【BIG】【MEDIUM】【SMALL

Here is an important principle to keep in mind about the extrusion. These principles can help you save money, producing high quality products and a more efficient use of equipment. The basic principle of extrusion machinery mechanism 1 is simple - a screw rotates in the cylinder to move forward and put the plastic. A screw or an inclined plane ramp is actually wound on the central layer. Its purpose is to increase the pressure in order to overcome a large resistance. To an extruder, there are three kinds of resistance to be overcome: the solid particles (feed) of the cylinder wall before the screw is rotated a few times and the frictional force when the (feed zone) the mutual friction between them; melt adhesion of the cylindrical wall; melt is pushed forward when the internal resistance of the stream. Newton had explained that if an object does not to a given direction, then the force on the object on the balance in this direction. Not in axial movement of the screw, although it may be in the vicinity of the peripheral lateral rapid rotation. Thus, the axial forces are balanced on the screw, and if it is applied to a plastic melt with a great thrust forward it also applied to one and the same object in a rearward thrust. Here, the thrust is applied thereto in the inlet behind the bearings - on the thrust bearing. Most single screw is right-hand thread, screws and bolts, like woodworking and machine use. If viewed from behind, they are reverse rotation, because they want to try to spin the cylinder backwards. In some twin screw extruder, two-screw counter-rotating cylinder and the two crossing each other, and therefore must be a right direction, the other must be a left direction. In other twin screw engagement, two screws rotating in the same direction and therefore must have the same orientation. However, in either case have to absorb the force of the thrust bearing backward, Newton's principles still apply. 2 the principle of the hot extrudable thermoplastic plastics are - they melt when heated and solidifies again when cooled. Heat melted plastic come from? Preheat the feed and the cylinder / mold heater may play a role but when you start is very important, however, the motor input energy - motor to overcome the resistance of the melt viscosity during rotation of the screw in the cylinder body to generate frictional heat - all the most important source of plastic, for small systems, the low speed of the screw, and the high melt temperature of the plastic extrusion coating except for applications. For all other operations, recognizing the tube heater is not operating in the main heat source is very important, and therefore the role of extrusion than we anticipated might be small (see paragraph 11 principles). The cylinder temperature may still be important as it affects the teeth together or solids feed conveying speed. Die and mold temperature should normally be close to the desired temperature or the melt temperature, unless they are used for a specific purpose such as polishing, the fluid distribution or pressure control. 3 the principle of the deceleration in most extruder screw speed changes by adjusting the motor speed to achieve. Usually at about 1750rpm motor rotates at full speed, but this one extruder screw it fast. If so quickly rotated, the frictional heat is generated too much and too short a residence time of the plastic can not be prepared in a uniform, well stirred solution of the melt. Typical deceleration ratio and 10: 1: 1-20. The first stage can be either a gear pulley block, but the second stage gear and a screw positioned in the center of the final gear. In some slow-running machines (eg for UPVC double screw), there may be three deceleration phase and the maximum speed may be as low as 30rpm or less (ratio of 60: 1). At the other extreme, some very long for stirring can be run in a twin screw speed of 600rpm or higher, and therefore require a very low deceleration rate, and many deep cooling. Sometimes deceleration rate and task matching wrong - there will not be using too much energy - and it is possible to change the maximum speed between the motor and the first to add a pulley block deceleration phase. This is either the screw speed increases to exceed the previously reduced maximum speed limit or the maximum speed of the system allowing a larger percentage
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Operation. This will increase the availability of energy and reduce the amperage and avoid motor problems. In both cases, according to the material and the need for cooling, the output may be increased.