Explain the extrusion technology of PET strapping production line
1. The crystallizing drying tower adopts the rotary honeycomb dehumidifier. After dehumidification, the working dew point of the air is - 40 ℃ to - 65 ℃. After dehumidification and drying, the moisture content of the material is ≤ 0.2%, which can improve the toughness of the product, reduce the cracking degree between the necks, and bring its own strengthening system, so that the pet material can complete the fixed polycondensation and drying process. The viscosity can be increased to 0.8-1.2, and the molecular weight can be increased to 30000.2. Special designed screw is used. High output, low energy resistance, small damage of molecular structure of materials, small reduction of melt viscosity, fast heating of screw with resistance heater, high efficiency, digital automatic temperature controller can automatically control temperature.
3. The mould adopts the fast automatic screen changing device with high efficiency. It is equipped with melt pressure sensor and alarm device. The screen changing is timely with less waste. The melt metering pump can stabilize the melt pressure, maintain the stable pressure and keep the embryo stable. The mold is simple to replace. It is equipped with 4-Pair die and can produce 9-25 belts. It has fine workmanship to ensure the embryo stable.
4. The constant temperature casting water tank is mainly made of stainless steel frame and lifting device, which can move up and down, easy to operate quickly, and can cool materials quickly, so that the temperature can reach the granulation structure below the melting point. The granular molecular structure is easy to be stretched to obtain high quality products.
5 first preheating machine The function of the first preheat machine is to preheat the extruded film to reach the drawing temperature quickly after the band breaks out of the constant temperature water tank. The purpose is to preheat the extruded film to the drawing band embryo on the preheat roller and circle the S-shape on the upper plate of the preheat roller, so that the extruded film is in full contact with the surface of the preheat roller. This design can make the pet band embryo double-sided heating, medium oil heating, temperature controlled by the mold temperature machine, with low power consumption.
6. The first drawing machine of the first drawing machine is mainly composed of the traction roller clamping device, transmission device, bracket, damper and electric control, which mainly completes the function of directional drawing and traction. The damper can ensure that the belt embryo can be stretched through the fixed point after heating, so as to ensure the precise point stretching.
7 hot air stretching box is mainly composed of fan, heating pipe, cylinder device and frequency converter. The heating temperature is adjusted by the temperature control meter, and the upper and lower parts of the box are heated by the fan to create the circulating air. The distance between the closed and the thermal is closed. After entering the hot air box, the packing belt quickly reaches the required stretching temperature. In the hot air stretching box, the temperature is constant, controlled by the temperature control, and the fan speed can be adjusted.
The second drawing machine is composed of traction roller clamping, transmission box, damper and electric control, which mainly completes the function of directional drawing and traction. The damper can ensure that the belt embryo is stretched through the fixed point after heating.
9. The packing belt of the embossing machine is formed after the longitudinal stretching. The embossing machine mainly prints patterns on the packing belt to improve the transverse tensile strength and friction force. The embossing machine is mainly composed of the embossing roller and bracket, and both sides are equipped with adjusting bolts to achieve the ideal printing effect. The transmission of embossing roller is adjusted by the function of frequency conversion torque to ensure the simultaneity of upper and lower roller and traction speed.
When the packing belt is stretched, it will cause the corresponding movement of polymer chain segment, and recrystallization will make the product have internal stress under the action of external force. The heat treatment method is adopted to eliminate the internal stress in the packing belt and prevent the directional release of the packing belt after stretching.
The third tractor mainly plays the role of traction after setting the packing belt.
The cooling bracket is mainly used for further cooling and packing to control the crystallinity and relieve the internal stress so as to avoid curling deformation. The S-shaped bending guide is adopted to slow release and eliminate the internal stress of the embryo, so as to achieve a good effect of winding.
The fourth traction mainly completes the traction and guidance function in the finalized packing belt. Power 3kw.
The winder mainly consists of sleeve, reel, roller, guide bracket, stretching roller, transmission system and electric control system. When the automatic meter counting control system reaches the set length, it will automatically stop cutting the belt, and the next winding can be switched.
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