Some issues with PVC centralized feeding

Published Time:

2022-05-10

Currently, as labor and energy costs account for an increasingly larger proportion of production costs, and the impact of environmental pollution on health is becoming more significant, how to improve the intelligent feeding level of PVC centralized 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.

Some Issues with Centralized PVC Feeding

Currently, as labor and energy costs account for an increasingly larger proportion of production costs, and the impact of environmental pollution on health is becoming more significant, how to improve the intelligent feeding 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 PVC centralized feeding projects. However, from an overall teaching effect, in the centralized feeding part of the extruder hopper, the following problems are generally considered to exist:

The extruder polyvinyl chloride hopper concentrates raw materials, generally using chain or spiral long-distance multiple extruders, set on each extruder's high and low level switch hoppers. Once one of the hoppers requires feeding, the conveyor must immediately operate, leading to frequent starts and stops, seriously affecting the stability of the equipment;

In addition, once the failure of a low-level switch control is discovered, it will lead to the failure and shutdown of the extruder. If the high-level switch fails, the conveyor will be jammed due to continuous operation;

During the consumption of polyvinyl chloride powder in the extruder, the material level changes greatly, and "dropping" and "bridging" phenomena are prone to occur during the discharging process, easily causing the extruder screw to break. More importantly, uneven feeding leads to serious quality problems of uneven wall thickness.

Solutions

Use a programmable logic controller to collect the start-up and speed signals of the main motors of each extruder in the downstream conveying of the entire pipe chain, and then perform numerical calculations on the speed signals of each extruder to control the feeding amount of the extruder;

Then, the feeding amount required for each production line can be calculated by controlling the feeding amount, and then the feeding amount is converted into the speed of the conveying pipe chain, and the speed of the conveying pipe chain is adjusted 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 usage, and 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 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 feed port of the corresponding pipe chain conveying pipe of the extruder, stop the feeder, 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, ensuring that even if most of the extruder hoppers are full in extreme cases, the powder pressure generated by the pipe chain "scraper" can be effectively released without leakage.

Tags:

How to solve the problem of PVC centralized material supply?

Magnetic material knowledge sharing from an automatic batching manufacturer of magnetic materials