Practical application of high-efficiency and energy-saving extrusion technology in PS sheet production lines

Extrusion technology has been used in thermoplastics for more than 80 years. With the rapid development of the chemical industry and the continuous emergence of new thermoplastics, extrusion technology has gone through many technological iterations. Its products are widely used in daily life, national defense, military industry, aerospace and other fields, with more and more applications and an increase in output. getting bigger. With the large-scale rise of the plastics industry, its energy efficiency has received increasing attention. Nowadays, high efficiency, energy saving, large output and automation are the three focuses of the plastic extrusion processing industry, especially high efficiency and energy saving, which is in line with the national energy conservation and emission reduction policy, especially in the plastic processing industry. This article focuses on the practical application of high-efficiency and energy-saving extrusion technology in PS sheet production lines, and compares the advantages and disadvantages of various technologies, which has certain reference significance for manufacturers or users of such production lines.

PS sheet production line extruder drive system

During the extrusion and plasticizing process of the extruder, 10%-25% of the energy comes from the heating of the external heating ring (or thermal oil), and the rest mainly comes from the drive system of the extruder, that is, the mechanical energy of the motor is converted into plasticized Thermal energy (may be generated by friction or shear). The current mainstream structure is an alternating current (DC) motor driven gearbox, which drives the screw to rotate after deceleration through the gearbox. In this subsystem, the transmission efficiency of the motor and gearbox is our focus, but we often only focus on whether the speed ratio is appropriate and ignore the efficiency of the motor and gearbox.

The efficiency of my country's small and medium-sized AC motors (three-phase asynchronous motors) is 87%, that of variable frequency motors can reach 90%, and that of foreign advanced motors can reach 92%. The transmission efficiency of the gearbox is generally ignored. The main reason for this neglect is that most people don't seem to have any better replacement parts to replace their transmission. The transmission efficiency of different transmission ratios is slightly different, and the general transmission efficiency can reach more than 95%. After looking at the above data, we immediately realized that many common parts actually have a lot of room for efficiency improvement. However, increased efficiency means increased procurement costs. But the bigger problem is that in order to compete with equipment, PS sheet production line manufacturers may not introduce this knowledge to customers, or use expensive but energy-saving parts. The advent of direct drive changed the substitution problem for this subsystem. In addition to the high price, the efficiency of direct drive is also greatly improved, reaching about 95%. But if it is a conventional three-phase asynchronous motor with a gearbox, its transmission efficiency is 87% X 95%≈82.6%, which is far behind the direct drive system.

Many users do not have an intuitive understanding of this difference. Let’s take a conventional two-machine co-extrusion PP PS blister production line as an example, which is very vivid. This type of domestic production line generally uses φ120 single-screw extruder and φ65 single-screw extruder, with motor powers of 132KW and 55KW respectively. Calculated based on 70% of the average load in production, the hourly energy consumption difference between the direct drive system and the traditional system is (132 kw+55kW) x 70% x (95%-82.6%) = 16.23 kw. Since the extrusion production line operates 24 hours a day Continuous production, this is already a very large energy saving data, that is to say, by changing the drive system, the annual energy saving of this production line is 16.23kW Or so, but this transformation is obviously cost-effective. How can PS sheet production line manufacturers communicate this issue with customers, so as to ultimately gain customer approval.