PET film slitting machine upgrade solution: the key to improving accuracy and speed

At a time when the demand for optical films, new energy battery separators and high-end packaging materials is blowing out, the importance of PET film as a substrate is self-evident. However, in the back-end of film production, slitting and rewinding often becomes a bottleneck that restricts production capacity and quality. How to improve the slitting speed while ensuring micron-level accuracy through technological upgrading has become the focus of attention of many film processing companies.

This paper will discuss the key path of PET film slitting machine upgrade from four dimensions: tension control, correction system, tool holder design and intelligent operation and maintenance.

1. High-precision tension control: from "constant" to "dynamic adaptive"

PET film has memory properties and is prone to shrinkage or wrinkles after stretching. Traditional slitting machines mostly use constant tension control, but in the process of high-speed start-stop and acceleration and deceleration, it is very easy to cause tension fluctuations due to inertia, which can cause tensile deformation or uneven winding.

Upgrade plan:

• Closed-loop vector control: The original ordinary frequency conversion drive is upgraded to vector frequency conversion control with encoder feedback to realize the decoupling of tension and speed during the unwinding and unwinding process.

• Combination of floating roller and pendulum roller: The floating roller swing arm mechanism driven by a low-friction cylinder or servo electric cylinder is introduced, which is adjusted in real time through the position sensor to absorb tension fluctuations and ensure that the film is always in a "flat" state during the slitting process.

• Taper tension control: For thick PET or hard film, the winding taper tension technology is used to automatically reduce the tension according to the change of coil diameter to prevent the burst of tendons or chrysanthemum core defects caused by internal looseness and external tightness.

2. Correction system upgrade: from "following" to "predicting"

The slitting accuracy directly depends on the edge positioning before slitting. Traditional photoelectric guidance often has lag and is easily interfered with by film transparency and ambient light.

Upgrade plan:

• High-precision ultrasonic/CCD correction: For transparent PET film, abandon the misjudgment infrared sensor and use ultrasonic sensor or high-resolution CCD camera. CCDs not only detect edges but also identify printed marks or specific defects, enabling more accurate path planning.

• Servo drive response: The drive of the correction frame is changed from an ordinary motor to a servo motor with high-speed response, and with a high-performance correction controller, the response time is shortened to milliseconds, ensuring that the edge swing is controlled within ±0.1mm at a high speed of 600 m/min.

3. Slitting tool holder optimization: the ultimate control of cutting and dust

One of the biggest headaches in PET film slitting is the dust and debris generated by cutting edges, which will directly lead to defective products in the coating or lamination process once they adhere to the film surface. In addition, deep grooves can accelerate blade wear.

Upgrade plan:

• Blade Material Upgrade: Replace regular HSS blades with carbide or ceramic-coated blades to extend blade life, keep edge sharp, and reduce stretch burrs caused by blunt knives.

• Air Float Cutter and Cushion Knife Technology: Air suspension deflectors are introduced to create a micro-positive pressure at the cutting point, blowing away dust and cooling the blade. At the same time, the scratch-free bottom roller or rotary pad knife technology is used to avoid groove marks caused by long-term fixing point cutting of the lower cutter roller, so as to ensure the long-term consistency of the slitting width.

• Disc Shear Optimization: For ultra-thin films, optimize the clearance and overlap of the upper and lower tools. Upgraded high-precision tool holder slip adjustment mechanism to ensure shearing, not tearing.

4. Winding mechanism: solving "slippage" and "curling edge"

The neatness of the winding end face is a visual reflection of the quality of the slitting. PET film has a smooth surface and low friction coefficient between layers, and is prone to axial slippage during high-speed winding, resulting in end face misalignment.

Upgrade plan:

• Contact/gap take-up switching: Upgraded to two-station rewinding with contact rewinding and gap take-up switching. For ultra-thin PET, gap coiling is used to avoid crushing; For thick films, use contact rollers to smooth out air bubbles.

• Roller pressure curve control: The programmable roller pressure system is adopted, and the roller pressure is reduced linearly or curved as the roll diameter increases, so as to avoid film adhesion caused by excessive internal pressure when the coil diameter is large.

• Anti-static elimination: Install a high-power pulsed static elimination rod to eliminate static electricity generated by high-speed friction of PET, prevent film layer adsorption and sliding, and reduce dust adsorption.

5. Intelligent O&M: MES interconnection and predictive maintenance

The real upgrade is not only the optimization of the mechanical structure, but also the digitalization of production management.

Upgrade plan:

• Data Acquisition and Traceability: Install PLC and touch screen configuration systems for the slitting machine to record the running speed, tension curve, slitting length and alarm history in real time. Access to the MES system through OPC UA protocol to realize the whole process traceability of production data.

• Predictive maintenance: Vibration and temperature sensors are installed in critical parts such as spindle bearings and rewinding chucks. Analyze the operating status of the equipment through algorithms, warn of bearing wear or shaft bending in advance, and avoid unplanned downtime.

Epilogue

The upgrade of PET film slitting machine is a systematic project. It requires equipment suppliers to not only provide precision machining capabilities, but also a deep understanding of material properties and the ability to integrate electrical controls.

Through the above-mentioned five-in-one upgrade of "tension precision + intelligent correction + dust-free tool holder + winding stabilization + operation and maintenance digitalization", enterprises can not only increase the slitting speed by 30%-50%, but also increase the yield rate to more than 99%, and win the initiative in the fierce market competition.