With the advantages of light weight, high strength, waterproof, corrosion resistance and recyclability, PP hollow boards are widely used in logistics packaging, advertising decoration, electronics and hardware, agricultural warehousing and other industries. As the core automatic equipment for hollow board production, the PP hollow board extrusion line integrates raw material treatment, melt plasticization, forming, cooling traction, cutting and stacking. The coordinated operation of each module directly determines the precision, flatness and overall quality of finished boards. This article briefly analyzes the core structure and working principle of the production line.

Adopting an integrated modular design, the production line consists of eight core units: raw material conveying and pretreatment unit, melt extrusion and filtration unit, mold forming unit, vacuum shaping and cooling unit, multi-stage traction and leveling unit, precision cutting unit, finished product stacking unit, and intelligent electric control system, realizing fully automatic continuous production from plastic particles to finished boards.

Composed of a vacuum feeder, drying mixer and storage hopper, the raw material pretreatment unit is the first production procedure. It automatically conveys, mixes and dries PP particles and functional additives, removes moisture and impurities from raw materials, avoids defects such as bubbles, cracks and spots on boards, and ensures stable plasticization and forming.

The melt extrusion and filtration unit is the plasticizing core of the production line, including a single-screw extruder, hydraulic screen changer and melt metering pump. The optimized single-screw extruder with sectional temperature control uniformly melts and plasticizes PP particles into homogeneous melt. The non-stop hydraulic screen changer filters impurities to ensure melt purity, while the metering pump precisely stabilizes melt pressure and flow, avoiding board thickness deviation.

Centered on a special T-die, the mold forming unit determines the hollow grid structure of boards. The pressure-stabilized and filtered melt passes through the special die flow channel to extrude standard hollow grid board blanks at one time. The precision shunt design balances melt pressure and flow velocity, adapting to the production of PP hollow boards with thicknesses from 2mm to 14mm and different widths, ensuring uniform and standard board structure.

The vacuum shaping and cooling unit comprises a vacuum calibrating table, water circulation cooling system and negative pressure vacuum system. High-temperature soft board blanks fit the shaping mold under negative pressure adsorption and cool down rapidly and evenly to fix the board size and hollow structure, correcting flatness and preventing warping and deformation. The independent dual-vacuum system ensures stable negative pressure across the whole area, improving shaping accuracy and product consistency.

The multi-stage traction and leveling unit includes a primary traction machine, constant-temperature annealing oven, secondary cooling mechanism and dual-track traction machine. It realizes uniform board conveying, eliminates internal stress through annealing treatment to prevent subsequent deformation and cracking, and completes deep board cooling. The dual-track tension control system ensures stable conveying without stretching or slipping. High-end models can be equipped with a corona treatment device to enhance surface adhesion for printing, lamination and other deep processing.

The precision cutting unit is mainly composed of a servo cross-cutting machine, edge trimming device and conveying mechanism. With precise servo positioning, it realizes automatic cutting according to set lengths with smooth, burr-free cuts and tiny dimensional errors. The edge trimming device automatically standardizes board width, supporting continuous production of various specifications.

The finished product stacking unit is an automatic material receiving and stacking device. It automatically stacks and counts finished boards neatly, replacing manual operation, improving production efficiency, reducing human errors, and facilitating subsequent packaging, warehousing and transportation.

As the core control system of the production line, the PLC-based intelligent electric control system integrates temperature control, frequency conversion speed regulation, fault alarm and remote monitoring modules. It centrally manages core operating parameters such as temperature, pressure, speed and flow, realizes synchronous linkage and closed-loop automatic operation of all units, supports one-click parameter adjustment and automatic fault alarm, reduces energy consumption and scrap rate, and ensures stable and efficient operation of the production line.

In conclusion, each unit of the PP hollow board extrusion line features clear division of labor and efficient coordination, forming a complete closed-loop production system. The modular precision structure design guarantees stable product quality and equipment versatility, meeting the mass production demands of multi-specification and multi-scenario hollow boards. It is a key intelligent equipment in the plastic new material and packaging industry.