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What should I pay attention to when purchasing an extruder?

2019-03-15 16:30:21

The wide application of plastic products has promoted the rapid development of the plastic machine industry, and the extruder has an important position in the plastic machine industry. The extruder can be divided into single-screw, twin-screw and multi-screw extruders according to the number of screws. How to choose the right extruder and what to pay attention to when buying the extruder has always been a problem for some users. Please follow the science and technology company to see what you need to pay attention to when purchasing an extruder.
Option 1: Screw speed
The speed of the screw is the most critical factor affecting the productivity of an extruder. The screw speed not only affects the extrusion speed and extrusion amount of the material, but more importantly, the extruder achieves a good plasticizing effect while achieving high yield. In the past, to increase the output of the extruder, the main method is to increase the screw diameter. Although the screw diameter increases, the material extruded in a unit time increases. However, the extruder is not a screw conveyor. In addition to extruding the material, the screw also extrudes, stirs, and shears the plastic to plasticize the plastic. Under the premise of constant screw speed, the screw of large diameter and large screw groove is not as good as the screw of small diameter.
Therefore, modern extruders mainly increase productivity and pipe quality by increasing the screw speed. When the screw diameter is constant and the screw speed is increased, the torque that the screw is subjected to will increase, and when the torque reaches a certain level, the screw may be twisted. However, by improving the material and production process of the screw, the screw structure is rationally designed, the length of the feed section is shortened, the flow rate of the material is increased, and the extrusion resistance is reduced, which can reduce the torque and improve the bearing capacity of the screw.
Option 2: Screw structure
The screw structure is the main factor affecting the productivity of the extruder. If there is no reasonable screw structure, simply increasing the screw speed to increase the extrusion amount is against the objective law and will not succeed. The design of the high speed and high efficiency screw is based on high speed. The plasticizing effect of such a screw at a low rotational speed is inferior, but the plasticizing effect is gradually improved after the screw speed is increased, and the best effect is obtained when the design rotational speed is reached. At this time, there is a high production capacity and a qualified plasticizing effect.
Option 3: barrel structure
The improvement of the barrel structure is mainly to improve the temperature control of the feed section and to set the feed chute. Whether the temperature of the water jacket is reasonable is very important for the stable operation of the extruder and efficient extrusion. If the temperature of the water jacket is too high, the raw material will soften prematurely, and even the surface of the raw material particles will melt to weaken the friction between the raw material and the inner wall of the barrel, thereby reducing the extrusion thrust and the extrusion amount. However, the temperature should not be too low. The barrel with too low temperature will cause the screw rotation resistance to be too large. When the bearing capacity of the motor is exceeded, the motor will be difficult to start or the rotation speed will be unstable. Bell Machinery uses advanced sensors and control technology to monitor and control the water jacket of the extruder to automatically control the water jacket temperature within the optimum process parameters.
Option 4: Accelerator
Under the premise that the structure is basically the same, the manufacturing cost of the reducer is roughly proportional to its external dimensions and weight. Because the shape and weight of the reducer are large, it means that there are many materials consumed during manufacturing, and the bearings used are also relatively large, which increases the manufacturing cost. In the same screw diameter extruder, the high-speed and high-efficiency extruder consumes more energy than the conventional extruder, and the motor power is doubled. It is necessary to increase the frame number of the reducer accordingly. But a high screw speed means a low reduction ratio. The same size of the reducer, the low reduction ratio compared to the large reduction ratio, the gear modulus increases, the reducer's ability to withstand the load also increased.
Therefore, the increase in the volumetric weight of the reducer is not linearly proportional to the increase in motor power. If the derivation is used as the denominator, the speed of the reducer is divided, the number of high-speed and high-efficiency extruders is small, and the number of ordinary extruders is large. In terms of unit output, the high-speed high-efficiency extruder has low motor power and low weight of the reducer, which means that the unit production cost of the high-speed and high-efficiency extruder is lower than that of the ordinary extruder.
In addition, the production cost, production efficiency, supplier and operability of the extruder are all things that should be considered at the time of purchase.

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