What are the problems with PVC centralized feeding?

Published Time:

2023-02-06

Currently, with the increasing proportion of labor costs and energy consumption costs in production costs, the impact of environmental pollution on health is becoming increasingly significant. How to improve the intelligence level of centralized PVC feeding in PVC pipe extrusion production lines, how to reduce production costs, improve PVC mixing precision, and improve the production environment has always been the goal pursued by manufacturers. At present, most pipe production equipment manufacturers are actively promoting centralized PVC feeding projects. However, from the overall teaching effect, it is generally believed that the centralized feeding part of the extruder hopper has the following problems:

Centralized PVC Feeding

1. The PVC hopper of the extruder concentrates raw materials, generally using chain or screw-type long-distance multiple extruders, set on the high and low level switch hoppers of each extruder. Once one of the hoppers is set, the conveyor is required to start feeding immediately, leading to frequent starts and stops, seriously affecting the stability of the equipment.

2. In addition, once the control of one of the low-level switches is found to be invalid, it will cause the extruder workbench of the enterprise to be unable to stop, and once the high-level switch is invalid, it will cause the conveyor to be stuck due to continuous economic operation.

3. In the process of consuming PVC powder in the extruder, the level changes greatly, and the phenomenon of "falling" and "bridging" is easy to occur during the feeding process, and the extruder screw is easy to break. More importantly, uneven feeding has led to serious quality problems of uneven wall thickness.

Solutions to the problem of centralized PVC feeding are as follows:

The PLC is used to collect the start and speed signals of the extruder main motor transmitted by the entire pipeline chain downstream, and then performs numerical calculation on the speed signal of the extruder to control the feeding amount of the extruder; then we can calculate the feeding amount required for the development of each production line by controlling the feeding amount, and then we can convert the feeding amount into the speed of the conveying chain to adjust the speed of the conveying chain in real time.

That is, when the speed of the downstream extruder main motor suddenly increases or the number of extruder runs increases, the feeding system will immediately detect the change in speed and the increase in material consumption, correspondingly increase the feeding speed, and then proportionally increase the transmission speed of the pipe chain; conversely, when the speed of the downstream extruder main motor suddenly decreases or the number of extruder runs decreases, the feeding system correspondingly reduces the feeding speed and proportionally reduces the conveying speed of the pipe chain.

In addition, the centralized PVC feeding system also reads the current and torque parameters downstream of each extruder. When the extruder exceeds the torque alarm, the feeding system will automatically close the feeding port of the corresponding pipe chain conveying pipe of the extruder, stop feeding, and not increase the feeding amount of the extruder, thereby reducing the output torque of the extruder and effectively protecting the extruder screw.

In addition, in terms of flexible long-distance, multi-machine powder conveying, it also has a unique full-load redundant pressure relief mechanical design to ensure that even if most of the extruder hoppers are full under special circumstances, the powder pressure generated by the pipe chain "scraper" can be effectively released without leakage.

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