The continuous flat press achieves continuous production of sheets through a dynamic hot pressing process. The process includes:

Feeding and pre-pressing: The paved slab enters the press entrance through a conveyor belt, and the pre-pressing section exhausts air and preliminarily shapes it through mechanical or hydraulic devices.

Segmented hot pressing: The slab enters the high-pressure zone, low-pressure zone and secondary pressurization zone in turn. The high-pressure zone (temperature 210–225℃, pressure 1.5–4.5N/mm²) quickly closes the slab and starts the curing of the adhesive; the low-pressure zone (temperature 210–215℃, pressure 1.0–3.2N/mm²) maintains plasticization; the secondary pressurization zone (temperature 190–195℃, pressure 0.8–2.5N/mm²) controls the final thickness and releases stress.

Cooling and board discharge: The pressed sheet is cooled and shaped in the cooling section, and cut by the automatic cutting system.

The design of the continuous flat press focuses on high efficiency and automation. The main structure includes:

Hot pressing system

(1) Rotating roller design: Some equipment uses upper and lower double rotating rollers (such as Hubei Ningfeng patent), and the roller surface is equipped with a ring-shaped electric heating block, which is driven by a servo motor to rotate relative to each other and evenly apply hot pressing.

(2) Ferris wheel structure: such as Henan Jianuowei patent, the rolling shaft drives 6 hot presses to rotate in a cycle, and the convex and concave molds are used to achieve continuous pressing without stopping to change materials.

Heating and control systems

(1) Electric heater or thermal oil heating, combined with infrared monitoring of the slab status, to ensure temperature uniformity.

(2) Siemens S71500PLC or hydraulic system to achieve precise adjustment of pressure and speed, and support online thickness detection and correction.

(3) Automated auxiliary devices: such as automatic push mechanism (electric push plate discharge after hot air drying), conveyor belt synchronization system, etc., to reduce manual intervention.

Temperature control: The temperature difference between the surface and the core layer needs to be strictly managed. The temperature in the high-pressure area is 220-230°C, and the secondary pressure area is reduced to 190-195°C to avoid over-curing of the surface.

Moisture content control: The moisture content of the surface wood chips is 10.5-11.5%, and the moisture content of the core layer is 5.5-6.0%, balancing steam emission and gluing effect.

Pressure curve: The initial pressure in the high-pressure area is 3.0N/mm², which gradually decreases to 1.25N/mm² in the secondary pressure area to reduce the internal stress of the board.

  （1）Promote adhesive curing: Ensure adhesives like urea-formaldehyde(UF),phenol-formaldehyde (PF), or melamine-urea-formaldehyde (MUF) resin fully cure within the specified time to achieve optimal bond strength.

  （2）Plasticize wood fibers: Heat and pressure soften and plasticize wood fibers, enabling tight interlocking and compression to form a uniform mat structure.

  （3）Control moisture migration and evaporation: Manage the rate of moisture evaporation and steam removal from the mat to prevent blistering, delamination, or local overheating.

  （4）Achieve preset temperature profile: Establish precise temperature gradients along the mat's travel direction (length) and thickness to match adhesive curing kinetics and moisture migration.

  （5）Ensure temperature uniformity: Maintain highly uniform temperature distribution across the press width (transverse) and length (longitudinal) to avoid local defects (e.g., pre-cure, under-cure, density variations, warping).

  （6）Optimize efficiency and energy consumption: Minimize pressing time and maximize thermal energy utilization while ensuring quality.

The press is divided into multiple independently controlled temperature zones (typically 6–20+), aligned along the board travel direction (infeed to outfeed).

 Each zone has its own platen(s), heating/cooling medium channels, temperature sensors (thermocouples or RTDs), and dedicated control loop (usually PID-based).

 Rationale: The mat's physical state (temperature, moisture, cure level) changes dynamically. Rapid heating is needed at the infeed, sustained curing temperature in the middle, and cooling at the outfeed. Zoning enables precise adaptation.

Typical Range: Modern presses have 12 to 30+ zones. Key factors:

      Total Press Length: Thicker boards/higher quality require longer presses and more zones. 

E.g.:

    Thin board press (~20m): 12-16 zones.

    Medium-thick board press (30-40m): 20-25 zones.

    Thick board/Specialty press (40m+): 30+ zones.

      Control Precision Requirements: Finer control needs more, shorter zones.

1.  Physical Basis: Zones correspond to independent, modular platen units with dedicated flow channels, ports, and valves.

2.  Quantity Determinants: Set by press length, target board thickness, and process precision needs (typically 12-30+ zones).

3.  Functional Logic:

      Front (Few zones): Highest temperature, rapid heating, "skin" formation.

      Middle (Most zones): Stable high temperature, main curing, core quality.

      Rear (Few zones): Gradual cooling/setting, stabilization, over-cure prevention.

4.  Advanced Compensation: Width-wise sub-zoning (e.g., L/C/R) may be used for ultimate transverse uniformity.

This modular physical design, driven by process functionality, enables the continuous flat press to precisely "map" the required dynamic temperature profile along the board path – the indispensable technological foundation for high-quality, stable particleboard production.