Working Principle & Core Technologies of Winders in Extruders

I. Working Principle

As a key end device in extrusion production lines, the winder’s core function is to wind continuously extruded products (such as films, pipes, and wires) into neatly arranged rolls under specific tension. This enables uninterrupted production and efficient storage of finished goods. The workflow is as follows:

Reception and Guiding: Products exiting the extruder or tractor are aligned via guiding mechanisms (e.g., guide rollers, guide wheels) to ensure stable entry into the winding system.

Tension Control: Tension sensors monitor product tension in real time and feed data back to the control system (such as a PLC). Motors (servo or variable-frequency) then adjust winding speed to maintain consistent tension—preventing stretching or breakage from over-tightening, or loose winding from under-tightening.

Winding Formation: Depending on the product, either center winding (driven by active reel rotation) or surface winding (powered by friction between pressure rollers and the roll surface) is used. A traversing mechanism (e.g., lead screw, servo motor) ensures even axial alignment of the product on the reel, forming uniform rolls.

Linkage Adaptation: The winder, extruder, and tractor operate in closed-loop speed control (winding speed ≈ traction speed ≈ extrusion speed, with minimal tolerance). When roll diameter increases or extrusion speed fluctuates, the PLC adjusts motor frequency in real time to maintain stable, synchronized production line operation.

II. Core Technologies

Winder performance directly impacts product quality (e.g., flatness, dimensional stability) and production efficiency. Its core technologies focus on four key areas:

Tension Control System

Objective: Maintain constant tension amid changing roll diameters and speed fluctuations (requirements vary by product—e.g., films need uniform low tension, while pipes require deformation-resistant tension).

Implementation:

Real-time tension signals are collected using sensors (e.g., magnetic particle brakes, tension pendulums).

PID (Proportional-Integral-Derivative) algorithms rapidly adjust motor output torque (e.g., magnetic particle clutch excitation current, servo motor speed) to compensate for tension deviations.

For elastic materials (e.g., TPU) or easily deformable products (e.g., foam), segmented tension control is employed—gradually adjusting tension as roll diameter increases.

Precision Winding and Traversing Technology

Objective: Ensure products are neatly, densely arranged on the reel, avoiding overlap, wrinkling, or loose winding.

Implementation:

A servo-driven traversing mechanism (via lead screws or cams) precisely controls the reciprocating speed and stroke of guiding components, adapting to varying product widths (e.g., film width adjustment, wire laying pitch for filaments).

"Electronic gear synchronization" links traversing speed proportionally to winding speed (e.g., smaller wire diameters require higher traversing frequencies), ensuring wire arranging precision (with errors controlled within ±0.1mm).

For large-diameter products (e.g., thick sheets, large pipes), anti-offset guide wheel sets and real-time roll diameter detectors (e.g., ultrasonic sensors, encoders) dynamically adjust winding trajectories.

Speed Linkage and Synchronization Control

Objective: Achieve speed matching between the winder, extruder, and tractor to prevent product accumulation or stretching.

Implementation:

A PLC-based speed closed-loop system uses encoders to collect tractor/extruder speed signals, which serve as reference speeds for the winder, with real-time adjustments to winding motor frequency.

A "roll diameter compensation algorithm" maintains constant motor linear speed as roll diameter increases—dynamically adjusting motor speed via real-time roll diameter calculations to ensure synchronization with upstream equipment.

Automation and Adaptive Design

Objective: Boost production efficiency and accommodate diverse product requirements.

Implementation:

Automatic roll changing: A dual-shaft winding structure enables rapid switching to a standby shaft via pneumatic/hydraulic mechanisms once a roll is complete, allowing non-stop operation and reducing downtime.

Modular design: Quick replacement of reels, pressure rollers, or guiding components for different products (e.g., films, wires) minimizes changeover time.

Intelligent diagnostics: Integrated sensors monitor motor temperature, tension abnormalities, etc., with alarms and fault prompts displayed on the human-machine interface to facilitate maintenance.

Summary

The winder operates on the principles of "stable tension, precise winding, and synchronous linkage." Its technical edge lies in precise tension control, neat winding arrangement, efficient coordination with production lines, and adaptability to diverse materials and product forms. Optimizing these technologies directly determines the continuity, quality, and efficiency of extrusion production lines.