Microcomputer control system for extrusion foaming
DATE：2022/4/8 8:39:50 / READ： / SOURCE：This station
Microcomputer control system for extrusion foaming
At present, most of the control methods of extrusion foaming are still adjusted manually, which not only costs a lot of raw materials and test time, but also reduces the quality of foaming products. The application of microcomputer control technology has brought new hope to the modern extrusion foaming production line. The microcomputer control system of some commercialized extrusion foaming production lines can greatly reduce the fluctuation of thickness and density of foaming products, significantly reduce the waste and test run time, and improve the output and quality. Figure 587 is the schematic diagram of an extrusion foaming production line with microcomputer control system. The basic components of microcomputer control system are measurement unit, operation control station and command data terminal. Breathable membrane production line www.handern.com com1. Operation control station operation control station (PCS) can provide functions such as control, sensor data processing, display data collection, warning and record transmission. PCs includes a 16 to 32-bit microprocessor, which can complete sensor control and display the operation status of extrusion foaming production line. The display contents generally include: instantaneous profile curve of product cross section, distribution curve of relevant parameters in production (optional), etc. All displays can be expressed in color. Breathable membrane production line www.handern.com com
2. Instruction data terminal instruction data terminal (IDT) can usually support 8 operation control stations. IDT includes a microprocessor and printing equipment. Its main function is to print operation records, copy the contents displayed on the screen, save human operation data, etc.
3. One of the key tasks of microcomputer control system of measurement unit is data acquisition, which is usually completed by measurement unit. The system shown in figure 5-87 has a high-speed non-contact scanning device and corresponding sensing elements. With this advanced measuring unit, the thickness and weight (or density) can be measured quickly and accurately. Each PCs has two or more high-speed scanners, each scanning a plasticizing extruder: 2 a cooling extruder; 3 - high speed scanner including sensor; 4 - lower winding roll: 5 - upper winding roll; 6-high speed multipoint measuring device: 7-line speed control; 8 - operation control station: 9 - instruction data terminal; 10. Speed control of plasticizing extrusion screw; 11 - flow control of foaming agent; Breathable membrane production line www.handern.com com
The cooling extrusion screw speed controller has two sensors. These sensors move back and forth on the surface of foamed products at a variable speed of 0.3m/s. At present, there are two kinds of sensors for foamed products. (1) Electromechanical sensor this kind of electromechanical sensor is used to directly measure the thickness of foamed products, so it is also called thickness sensor. The measured thickness ranges from 0.25 to 25.4mm, and
8.9~101.6mm。 (2) Nuclear sensor nuclear sensor is used to measure the density of foamed products. It can automatically compensate the influence of product temperature change. All sensor signals are converted into digital signals and processed by microcomputer. The whole process of extrusion foaming is controlled by microcomputer through two links. One is a series of direct digital control links (DDC for short), and the other is a series of monitoring links. The specific control relationships are listed in table 22-5. It can be seen from table 5-23 that the monitoring link to control the thickness fluctuation is the linear speed of foam board, which realizes the thickness control by adjusting the linear speed of traction roller to match the extrusion speed. Each time the sensor scans to the end, the thickness value of the early average foam product measured at that time is compared with the target value. The computer accurately adjusts the linear speed of the traction roller according to the deviation between the measured value and the target value. The monitoring link to control the fluctuation of foaming density of products is the dosage of foaming agent. After processing the signal sent by the sensor, the computer obtains the average foaming density of the foaming board at that time. By comparing the average foaming density with the target density, the difference between the average foaming density and the target value can be obtained. The computer adjusts the amount of foaming agent according to the difference to reduce the difference between the average density and the target density. Control link purpose feedback variable linear speed reduction linear speed fluctuation active traction roller speed screw speed reduction screw speed fluctuation screw speed foaming agent reduction foaming agent dosage fluctuation foaming agent flow traction roller speed ratio reduction driven traction roller speed and main speed ratio (traction roller) Ratio fluctuation of the speed of the moving traction roller thickness measurement ratio of the thickness of the upper and lower winding rollers thickness control link thickness difference reduction thickness fluctuation objective reduction of the thickness measurement value of the products on the upper and lower winding rollers feedback variable thickness measurement value ratio of the foam board linear speed ratio of the upper and lower winding rollers monitoring link density reduction density change applicable index (TAD) Measure the density to make the thickness or density exceed the limit. Control the percentage of foaming agent flow. The thickness change of foaming plate controlled by microcomputer is 45% less than that controlled by operation. Similarly, microcomputer control also plays a great role in reducing the change of foaming density. Breathable membrane production line www.handern.com com
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