Raw material preparation → Stranding → Drying → Screening → Resin application (typically MDI or PF resin) → Oriented forming → Pre-pressing → Hot pressing (critical stage where continuous press operates) → Cooling → Trimming → Sanding → Inspection → Packaging.

OSB quality critically depends on hot-pressing parameters (pressure magnitude/distribution, pressing duration, temperature profile). Precise control is essential for uniform density, complete resin curing, accurate thickness, and optimal physical/mechanical properties. Traditional batch presses (e.g., multi-daylight presses) are inefficient, energy-intensive, and lack complex pressure control. Continuous presses, especially those with rapid-response hydraulic servo systems, are the ideal solution for high-quality, efficient OSB production.

II.Continuous Press Introduction 

Differs from batch presses (processing discrete panels) by enabling continuous, uninterrupted mat feed-through and pressing.

 

1.Working Principle:

      The formed mat (typically pre-pressed) is fed between two high-strength, heat-resistant endless steel belts.

      Driven by drums, the belts synchronously carry the mat through a long, heated pressing zone.

      Inside the press frame (pressing zone), sectional heated platens (usually oil-heated) and sectional pressing devices (hydraulic cylinders) are installed.

      As the mat moves at constant speed, it undergoes continuous, sectionally controlled heat and pressure, achieving resin curing (thermosetting adhesive) and thickness calibration.

 

2.Key Components:

     (1) Endless Steel Belts: Support, transport the mat, and transfer heat/pressure. Require extreme strength, flatness, thermal stability, and wear resistance.

Circulating steel strip

Continuous press machine's steel belt

     (2) Drive System: High-power motors and gearboxes ensuring smooth, synchronous, precise belt movement.

     (3)Heating System: Sectional heated platens with circulating hot oil (or steam), providing curing heat. Features zonal temperature control.

      (4)Pressing System: Core function of the hydraulic servo system. The press length is divided into dozens or hundreds of independent pressure zones. Each zone contains one or more hydraulic cylinders (plunger type), independently controlled by the hydraulic servo system to apply precise pressure to the belt (and thus the mat).

     (5) Press Frame: Massive steel structure designed to withstand enormous pressing forces (total force up to tens of thousands of tons).

     (6) Thickness Control/Guiding System: Ensures stable belt run and controls final panel thickness.

     (7) Lubrication System: Applies lubricant and cleans the interface between belts and platens/support rolls.

     (8) Control System: The central brain, integrating control of drive speed, zonal temperatures, zonal pressures (via hydraulic servo), lubrication, and safety.

  3.Advantages:

      Very High Production Efficiency: Continuous operation eliminates cycle downtime, significantly outperforming batch presses.

      Superior Product Quality: Sectional pressure control enables optimized pressure profiles (e.g., high pressure at entry for degassing, constant pressure during curing, low pressure at exit for springback control), resulting in more uniform density distribution, better physical/mechanical properties, and tighter thickness tolerances.

      High Flexibility: Facilitates rapid changes in panel specifications (thickness, length) and formulations.

      High Automation Level: Easily integrated with upstream (forming) and downstream (cutting) processes for automated lines.

      Relatively Low Energy Consumption: Continuous process minimizes heat loss from repeated platen heating/cooling cycles.

      Improved Working Environment: Automated operation reduces manual intervention.

1.System Components:

      (1)Servo Pumps / Variable Frequency Drive (VFD) Pump Units: Supply high-pressure hydraulic oil. Utilize servo motors or VFD-controlled motors to precisely match output flow/pressure to real-time demand, drastically reducing standby losses compared to traditional constant-pressure or fixed-displacement pumps.

      (2)High-Response Servo Proportional Valves: The system's "precision switches" and "flow/pressure regulators". Receive electrical signals (mA level) from the controller and adjust oil flow/pressure to the actuators (cylinders) with extreme speed (response times typically milliseconds) and precision. Core component for achieving 0.1-second system response.

      (3)Hydraulic Actuators (Plunger Cylinders): Mounted under each pressure zone, applying force directly or indirectly (via press platens/support rolls) to the steel belt. Servo valves control oil flow into the cylinders, precisely regulating their output force (pressure).

      (4)High-Precision Sensors:

          (4.1 )Pressure Sensors: Provide real-time feedback on actual zonal pressure for closed-loop control.

          (4.2) Position Sensors (Commonly Used): Monitor cylinder piston or platen position for precise nip/gap (panel thickness) control.

          ( 4.3 )Force Sensors (Sometimes Integrated): Provide direct measurement of applied force.

     (5)High-Speed Controller: Typically a high-performance PLC or dedicated motion controller. Receives signals from the production line (e.g., mat density, position, speed) and the press (set pressures, actual pressures, temperatures, speed). Performs rapid calculations (using control algorithms like PID or variants) and sends precise commands to each servo valve. Critical "brain" for achieving 0.1-second system response.

      (6)Accumulators: Absorb pressure fluctuations, provide instantaneous high flow (especially during rapid pressure increases), stabilize system pressure, and protect components.

      (7)Cooling and Filtration Systems: Maintain oil cleanliness and optimal operating temperature.

The time elapsed from the controller issuing an adjustment command (based on error calculation) until the hydraulic system adjusts the zonal pressure close to the new target value (e.g., reaching ≥90% of target) is ≤ 0.1 seconds. This is achieved through millisecond response of servo valves, high-speed controller computation, real-time sensor feedback, and optimized hydraulic circuit design (low damping, low compressed volume). This speed is crucial for compensating disturbances like mat density variations, moisture fluctuations, belt oscillations, or speed changes, ensuring pressure control tightly follows the set profile.

Advantages in OSB Continuous Presses:

     1.Ultimate Pressure Control Precision: Enables complex, position/time-dependent pressure profiles, optimizing mat degassing, curing, minimizing pre-cured layers, and enhancing core bond strength.

     2. Rapid Disturbance Rejection: 0.1s response instantly compensates for pressure variations caused by uneven forming, material inconsistencies, or speed adjustments, guaranteeing uniform panel thickness and density, significantly improving quality consistency and reducing waste.

    3. Superior Thickness Control: Combined with position sensors, enables more precise control of press nip and final panel thickness tolerance.

    4. High Energy Efficiency: Servo/VFD pumps supply oil on-demand, eliminating overflow losses common in traditional systems, substantially reducing power consumption.

    5. Reduced Maintenance Needs: Smoother pressure control minimizes system shock and vibration, extending the lifespan of critical components (belts, platens, hydraulic elements).

    6. Enhanced Production Flexibility: Enables rapid pressure setting adjustments for different panel thicknesses, density grades, or raw material changes.

 Hydraulic Servo OSB Continuous Press (0.1s Response):This press is the core equipment for high-quality, high-efficiency OSB production. It perfectly merges the high productivity of continuous pressing with the exceptional precision (sectional pressure control) and ultimate speed (0.1s response) of hydraulic servo technology.