Principle and structure of plastic pipe extruder production line

The plastic pipe extruder production line can be divided into four-choice-one production line, two-choose-one production line, one-choice production line, etc. The plastic pipe extruder is mainly used for plastic PVC pipes of various pipe diameters and wall thicknesses such as agricultural water supply and drainage, building water supply and drainage, and cable laying. The unit consists of conical twin-screw extruder, vacuum setting box, traction machine, cutting machine, turning rack and other parts. The screw extruder and traction machine adopt imported frequency conversion speed regulation device, and the vacuum pump and traction motor adopt high-quality products. There are two-claw, three-claw, four-claw, six-claw and other traction methods for traction. Let me introduce to you the working principle and composition of the plastic pipe extruder production line.

In recent years, our country's plastic pipe extruders have developed rapidly, the annual growth rate of PVC pipes has reached 8%, and the annual demand growth rate has reached 2%. Among plastic pipes, the consumption of PVC pipes is far ahead, and it is widely used in water supply and drainage pipes. Due to the relatively mature technology, in recent years, PVC water supply pipes have not invested much in product innovation, relatively few new products, many common products in the market, few high-tech and high value-added products, and most of the same general products and low-end products. There are fewer high-end products.

At present, our country's plastic pipe production capacity has reached 3 million tons, which can be divided into three categories: PVC, PE and PP-R pipes. PVC pipe is the plastic pipe with the largest market share, accounting for nearly 70% of plastic pipes. There are more than 1600 plastic pipe production lines. The annual production capacity is more than 2.5 million tons. In 2003, the annual output of PVC pipes (pipe fittings) reached more than 1.2 million tons. In plastic pipes, PVC accounts for 70%, PE accounts for 25%, PP-R accounts for 4%, and others account for 1%.

Working principle of plastic pipe extruder production line:

In the production process, since the PVC pipe is a heat-sensitive material, even if a heat stabilizer is added, it can only increase the decomposition temperature and prolong the stabilization time without decomposition, which requires strict control of the molding temperature of the PVC pipe. Therefore, the extrusion temperature should be determined according to the formula, extruder characteristics, mold structure, screw speed, temperature measurement point position, thermometer error, temperature measurement point depth and other factors.

The pulling speed of the plastic pipe production line directly affects the pipe output and pipe wall thickness. The instability of the traction speed will lead to the increase or decrease of the PVC pipe diameter. The pulling speed should closely match the tube extrusion rate. In normal production, the pulling speed should be 1% or 10% faster than the extrusion speed. The slower the traction speed, the thicker the pipe wall, the faster the traction speed and the thinner the pipe wall, which will also increase the longitudinal shrinkage and internal stress of the PVC pipe, thereby affecting the pipe size, qualification rate and use effect. The following simple methods can be used to adjust the pull rate in production. The extruded PVC pipe is placed in the traction track, but the track does not clamp the pipe. A difference was observed between the linear velocity of the track and that of the PVC pipe. If the pulling speed is slower than the extrusion speed, adjustments should be made until the wall thickness is satisfactory.

Extruder part of plastic pipe production line:

The extruder is equipped with a quantitative feeding device to match the extrusion volume with the feeding volume to ensure stable extrusion of the product. Due to the characteristics of the conical screw, the diameter of the feeding section is large, the heat transfer area and shear rate of the material are large, which is conducive to the plasticization of the material, and the diameter of the screw in the metering section is small, which reduces the heat transfer area and shear rate of the melt. cutting speed. Thus the melt can be extruded at lower temperatures. When the screw rotates in the barrel, the PVC mixture is plasticized and pushed to the machine head to achieve compaction, melting, mixing and homogenization, and achieve the purpose of exhausting and dehydrating. The feeding device and screw driving device adopt frequency conversion speed regulation, which can realize synchronous speed regulation.