How to Start the Pipe Extruder

How to Start the Pipe Extruder?

Proper use of equipment contributes to human-machine safety, reduces maintenance and downtime, enhances machine reliability, prolongs machine lifespan, and improves economic efficiency.

The operator is the direct user of the equipment. If the scientific, reasonable and accurate operation of the equipment cannot be guaranteed, and there are too many operation accidents, it will inevitably cause the maintenance party to be passive and affect production. If operators have poor skills in equipment maintenance or are unable to detect potential equipment hazards in a timely manner, it will lead to an increase in sudden equipment failures, disrupt equipment maintenance plans, and ultimately result in passive production. Operators are required to master equipment operation skills, as well as equipment maintenance and upkeep, learn equipment management knowledge, and achieve correct use, maintenance, inspection (discovering hidden dangers), and troubleshooting (simple faults). Require each employee to be familiar with the process requirements, understand the equipment structure, performance, and working principles. To understand the knowledge related to equipment, achieve the goal of “integrating operation and inspection”, and operate in an energy-saving and efficient manner.

1. The main components and functions of an extruder:

The extruder is mainly composed of two parts: the main engine and the auxiliary engine. Plastic extrusion molding machine, abbreviated as extruder, is a type of extruder that uses screw pressure to continuously extrude plasticized materials from the extruder barrel through the mold mouth, making them in a molten state. After shaping and cooling treatment, the extruder is divided into single screw, twin-screw, and multi screw types by traction. Currently, our company uses twin-screw extruders.

A. The host mainly consists of a rotating system, a temperature control system, a feeding system, and a vacuum exhaust system.

The functions of each part are as follows:

Rotating system: DC or variable frequency speed regulation is used to continuously adjust the speed of the screw from 0-31 r/min or 0-43 r/min, allowing the screw to extrude molten raw materials through the mold mouth.

Temperature control system: using an automatic temperature regulator with corresponding heating coils, thermocouples, and constant temperature devices (air-cooled, oil cooled), indirectly heating the raw materials as required to make them melt.

Feeding system: The material is continuously and evenly supplied to the screw of the extruder through a stepless speed regulation device or the weight of the raw material itself plus the hopper sealing plate, in order to achieve quantitative feeding and continuous extrusion through the mold mouth.

Vacuum exhaust system: equipped with a particle separator by a vacuum pump to extract water vapor, volatile substances, etc. generated during the melting of materials in the material cylinder, in order to remove moisture, volatile substances, etc.

B. Auxiliary machines mainly consist of shaping boxes (tables) or forming machines, traction machines, cutting machines, printing machines, flipping racks, etc.

The functions of each part are as follows:

Forming box (platform): A forming sleeve (mold) is equipped with spray or immersion cooling water, and a vacuum pump is used to create negative pressure inside the forming box (mold), so that the melted products are formed and solidified into qualified products.

Forming machine: composed of modules of a certain specification and quantity, the product extruded from the mold is shaped and cooled, and then continuously pulled onto the cutting machine for fixed length cutting (usually a corrugated pipe unit).

Tractor: Use a track or drum type tractor to smoothly and continuously tow the products extruded from the mold mouth of the main machine to the cutting machine and flipping rack. The change in tractor speed will directly affect the cross-sectional wall thickness and shape of the produced product.

Cutting machine: using pneumatic mechanical devices and length measuring devices to automatically or manually cut products according to the required length.

Printing machine: continuously printing or spraying the name, model, specifications, etc. of the formed product onto the produced product.

Flipping rack: Using pneumatic devices to detach products from the length counting station, in order to achieve the purpose of re counting.

2. The use, operation, and maintenance of molds: Correct process conditions, reasonable formulas, applicable process parameters, skilled operators, and correct operating methods are the key to invisible maintenance of molds.

A. Operation methods for dismantling and assembling molds:

Dismantling and installing screws and nuts: clockwise direction is tight, counterclockwise direction is loose (the tightening direction of screws in special molds may change).

The removal and installation of screws and nuts must be symmetrical one by one, with all screws and nuts loosened in diagonal order first, and then removed one by one.

When installing screws and nuts, first apply high-temperature grease (such as fluidized molybdenum oil, etc.) on the thread of the screw and nut, and then screw them all into place, symmetrically and diagonally. Depending on the size of the screw, use an appropriate force rod to lock the wrench sleeve.

Demoulding: According to the production plan, the person in charge commands. Before disassembling the mold, add or not add a small amount of shutdown material according to the actual situation. Try to squeeze the material produced in the barrel out of the mold mouth as much as possible. Depending on production or use, it is necessary to partially disassemble or dismantle the mold.

Dismantling and demoulding: After disassembling the outer mold body, diversion bracket, core rod and other components of the entire set of molds, remove the remaining materials, clean the adhesive and miscellaneous materials on each component, check that the mold is intact, apply anti rust oil, assemble the entire set of molds, and place them on the mold rack.

Semi demoulding: Based on the production schedule and mold structure, it is determined that only the core rod mouth mold needs to be replaced. Semi demoulding is carried out by removing the mouth mold and pressure plate, loosening the core rod rod rod nut or core rod connecting tooth. Remove the core rod and clean the material to a position where the core rod can be replaced (at this time, the material may expand due to heat). Install the mouth mold. Then clean the removed mouth mold, repair any damaged ones, apply rust proof oil, and place it on the mold frame.

For screws and nuts that are difficult to disassemble, they should be pre oiled or waxed before disassembly, which can save effort and reduce damage to screws and tools.

Mold installation: According to the production plan, it is necessary to replace the mold. First, find the mold, remember the specifications and models, search for the corresponding core rod and mouth mold, and complete the necessary screws, nuts, heating rings, sizing sleeves, sealing plates, printing equipment and tools. For those who cannot match the model, ask the person in charge to check if the size of the transition sleeve matches the connection between the mold and the merging core. Check if the heating device inside the core rod is intact, and clean the mold of oil stains, debris, etc. If it is rusted or damaged for a long time, it shall be repaired or polished. After that, the flange plate, mold body, mold adjusting screw, mold pressing plate, and locking screw connecting the machine table and the mold piece by piece, the gap between the mold and the mandrel shall be adjusted. If it is a profile mold, it shall be leveled with a level ruler. All connecting screws and nuts shall be screwed in place in order to connect with the thermocouple feedback line. Remember that the thermocouple must be inserted in place, and the sizing sleeve and vacuum box sealing plate, or the vacuum and cooling water connecting pipes on the profile sizing die shall be removed and replaced and installed horizontally with the mold. The accessories of the traction pressure plate, cutting fixture, and auxiliary equipment of the fixed length device must be verified to be correct before the mold installation is considered intact (replace B). In short, during the mold installation and removal process, screws or wrenches must be properly fitted and the surface of the flow channel must be protected from any damage.

About Kairun Machinery:

With 17 years of specialized expertise, Kairun Machinery Co., Ltd. is a leading manufacturer in the plastics industry, seamlessly integrating R&D, production, sales, and comprehensive after-sales service.

By leveraging our extensive manufacturing history and deep technical heritage, we deliver high-performance, turnkey solutions for plastic extrusion. Our diverse product portfolio includes:

• Pipe Production: Advanced lines for PE, PPR, PVC, and PVC-O pipes.
• Specialty Extrusion: High-efficiency corrugated and spiral pipe extrusion systems.
• Profiles / Strapping: PVC/WPC profile lines and PP/PET strapping tape production technology.
• Processing / Recycling: High-speed mixing units, as well as integrated granulation and washing systems.

At Kairun, we turn technical accumulation into industrial excellence, ensuring our clients receive robust and innovative machinery tailored to their production needs.

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