I. Observe the appearance and end-face shape of the roll material
1. Smooth end face without "chrysanthemum pattern" or "star shape" deformation. If the end face of the roll material shows an inwardly concave "chrysanthemum pattern" or an outwardly convex "star shape," it indicates that the tension taper setting is improper:
"Chrysanthemum pattern" is usually caused by an excessively large taper and an outer layer that is too loose, resulting in insufficient interlayer support;
"Star shape" is mostly caused by an excessively small taper and an outer layer that is too tight, causing radial pressure concentration.
2. No "wrinkling," "core collapse," or "edge bulging" phenomena.
Inner layer crushing and core tube deformation indicate that the initial tension is too high or the taper is insufficient, resulting in excessive pressure on the inner layer;
Loose outer layer and roll diameter collapse indicate that the tension decays too quickly or zero-speed tension is not maintained.
II. Checking Dynamic Stability During Operation
1. Tension Fluctuations Controlled Within a Reasonable Range
Observe the real-time tension curve using a tension sensor or floating roller feedback:
Under normal circumstances, the tension should smoothly decrease as the roll diameter increases.
Sudden changes, oscillations, or periodic fluctuations indicate inaccurate roll diameter detection or controller response delay.
2. Stable Tension During Acceleration and Deceleration
The system should have dynamic compensation capabilities during startup, shutdown, or speed changes:
A high-quality taper controller can automatically detect acceleration and deceleration states and adjust the output to prevent material breakage or loosening.
If material jitter or tension jumps occur at this time, check if "soft start" and inertia compensation functions are enabled.
3. Smooth and Impact-Free Roll Change Transition
Tension should switch smoothly without disruption during dual-station shaft changes:
It is recommended to reduce the tension to 70% immediately during roll change and restore it after 2 seconds to prevent film breakage.
Frequent material breakage may indicate that the dual-station output is not synchronized or the memory function is not enabled.
III. Evaluation of Unwinding Performance and Adaptability to Subsequent Processing
1. Uniform Unwinding Tension, No Sudden Loosening or Tightening
A properly adjusted taper tension system should ensure consistent tightness of the roll material from the inside out:
Stable tension during unwinding, without "slippage" or "jumping";
If the outer layer suddenly loosens or the inner layer breaks, it indicates that the taper curve does not match the actual requirements.
2. Applicable to High-Speed Slitting or Composite Processes
In subsequent processing, if material deviation, interlayer misalignment, or poor bonding occurs, it may stem from uneven tension of the original roll material. Even if the current rewinder is operating normally, the taper setting needs to be reviewed for rationality.
IV. Verification Based on Equipment Control System Parameters
1. Confirm Controller Operation in Taper Mode
The tension controller should be explicitly set to "rewinding taper control" mode, not constant tension mode. Some controllers automatically ignore the taper coefficient during unwinding, only affecting the rewinding end.
2. Verify the relationship between initial and final values and roll diameter.
The initial tension should be set reasonably based on the material width and tensile strength. The final value is generally 60%~80% of the initial value, corresponding to a full roll. Using a controller that supports "calculated taper" technology (such as the Chuying ST-9400) allows for linear taper adjustment in feedback control.
3. Check the compatibility between the output signal and the actuator.
The controller output is 0-10V (for frequency converters) or 0-24V (for magnetic powder brakes). Ensure correct wiring and a stable signal. Abnormal output may cause distorted actuator response, affecting the actual tension control effect.
