Raw material blending: PVC stabilizers, plasticizers, antioxidants, and other additives are sequentially fed into a mixer in specified proportions and according to the process sequence. The friction between the materials and the mixing equipment raises their temperature to the set processing range, after which a cooling mixer reduces the temperature to 39–49°C. At this point, the blend can be transferred to the extruder hopper.

2. Extruder Section: This machine is equipped with a metering feed system that ensures the extrusion rate matches the feed rate, enabling stable production. The feeding section features a larger diameter, providing a greater heat-transfer surface area and higher shear rates, which facilitate material plasticization. In contrast, the metering section has a smaller screw diameter, reducing both the heat-transfer area and the shear rate on the melt, allowing extrusion at lower temperatures. As the screw rotates within the barrel, it plastifies the PVC compound and conveys it toward the die, achieving compaction, melting, and uniform mixing, while also facilitating venting and dehydration. Both the feed system and the screw drive are equipped with variable-frequency drives, enabling synchronized speed control.

3. Extrusion die section: The PVC, which has been compacted, melted, and homogenized through mixing, is conveyed by the screw to the die; the extrusion die is a critical component for pipe formation.

4. The vacuum shaping water tank is used for shaping and cooling tubular products. It is equipped with a vacuum system and a water circulation system for shaping and cooling, features a stainless steel tank body, and employs circulating water spray cooling. Additionally, the tank is fitted with a front-to-back traversing mechanism as well as manual adjustment devices for lateral and vertical positioning.

5. The traction machine is used to continuously and automatically draw the cooled, hardened pipe material out of the die head, with variable-frequency speed control.

6. Automatic Cutting Saw: After the stroke switch controls the cut to the required length, the saw performs automatic cutting and, following a delay, flips the pipe rack to enable continuous production. The cutting machine uses a fixed-length limit switch signal as its command to complete the entire cutting process, maintaining synchronization with the pipe‑conveying system throughout. The cutting operation is driven by both electric and pneumatic actuators. Additionally, the machine is equipped with a dust‑extraction system that promptly removes and recovers the cutting debris.

7. The material‑turning operation of the material‑turning rack is controlled by a pneumatic cylinder via a pneumatic circuit. The rack is equipped with a limit switch: after the cutting saw has severed the pipe, the pipe continues to be conveyed; following a delay, the cylinder activates to perform the turning action, thereby completing the unloading process. After unloading, the system automatically resets after a few seconds of delay, awaiting the next cycle.

Hebei Shuangda Rubber and Plastics Machinery Co., Ltd. is a modern enterprise integrating research and development, manufacturing, and sales of complete sets of extrusion equipment for rubber, silicone, and plastics. The company’s main products include rubber extruders, rubber hose extrusion lines, three‑layer composite sealing strip extrusion lines, silicone sealing strip production lines, plastic sealing strip production lines, plastic profile production lines, plastic pipe production lines, elastomer extruders, and other extrusion equipment, as well as production machinery for engineering seals, automotive seals, wire and cable applications, air‑conditioning hoses, braided hoses, automotive hoses, waterstop strips, and related products.