The advantage of the plunger method for producing PE-XE pipe is that the investment of a single piece of equipment is small, the production is simple, and no subsequent cross-linking is required. However, one of the most important drawbacks of this production method is the low production efficiency, that is, the speed of the single pipe production line is extremely low. The speed of the single-pipeline production of the screw-type plastic pipe can reach 20 m/min or more, but the speed of the single-pipeline production of the PE-XE pipe by the plunger method generally does not exceed 1.5 m/min.

Analyze the factors that restrict the speed of PE-XE production lines and propose solutions to increase production speed.

Plunger method PE-XE production line speed working principle Piston method stamping method The key technology of extrusion PE-XE pipe production line is to use the crank linkage mechanism to convert the continuous rotary motion of the crank into the intermittent up and down reciprocating motion of the plunger; the plunger will The raw materials are intermittently punched into the flow passage, and the structurally optimized flow passage converts the intermittently entered solid raw materials into continuously extruded viscoelastic PE-XE pipe preforms.

This process is quite different from the working principle of a screw extruder.

First, the screw of the working element in the screw extruder is a continuous rotary motion, and the plunger of the working element extruded by the plunger method is reciprocating, and the continuous rotating motion can work smoothly at a high rotational speed, and the motion of reciprocating motion The faster the speed, the greater the vibration.

Second, the PE-XE melt viscosity is very high, which is why reciprocating extrusion must be used, and the flow rate of such a high melt is limited when flowing.

Third, the PE-XE melt must remain in the die for a sufficient period of time to allow the peroxygen to decompose and complete the cross-linking reaction with the PE. Factors affecting production speed The first of the above three items is to optimize the design of the RAM host to achieve the best production conditions. The speed of the plunger push is proportional to the frequency and stroke of the plunger movement. Generally speaking, the higher the frequency, the larger the stroke and the larger the amount of pushing material. But the improvement of these two items will also increase the vibration of the equipment. The optimized design and actual production test are optimized at a frequency of 4-8 times/s and a stroke of 30-40 mm.

PE-XE melt viscosity can be changed with few parameters, and some improvement can be made by adjusting the raw material formulation, but the production speed can be improved by improving the frictional properties of the melt and the mold surface. The third article is one of the most worthwhile topics for research. This one does not solve the problem, and the improvement of the last two can not greatly increase the output. In order to make the PE-XE pipe completely complete the cross-linking reaction and leave the mold, it is necessary to stay in the mold for a sufficient period of time. Second, there must be sufficient temperature, and the number of the three-crossing connection should be appropriate. The mold temperature is limited and it is impossible to rise to the temperature above the decomposition.

Solution to increase production speed Through the above analysis, three effective solutions to improve the output of plunger-punched PE-XE pipe: optimize the stroke and frequency of the plunger; add additives to improve the friction performance of the melt and the mold; moderately increase the mold temperature , lengthen the die and the length of the mandrel. After the above optimization, the production speed of the pipe of 20×1.9 can reach 1.8 m/min or more.

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