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Application of SUNFAR V260 Inverters in Winding Part of Film Blowing Machines

Abstract:

This article describes successful application of SUNFAR V260 vector inverters on the winding part of film blowing machines.

Keywords: Inverter; V60; PID; Tension; Film Blowing Machine; Winding

Foreword
   The film blowing machine is a kind of equipment which can heat, melt and blow plastic particles into films.

It mainly consists of blowing and winding parts. The winding part is to wind up films blown out and make them

smooth, free of wrinkling and having neat curled edges. The films on the winding shafts should have appropriate

degree of tightness to prevent films from stretching and deforming and to ensure quality. Therefore, constant

tension control must be adopted during winding. Presently, the aforesaid control is mainly achieved by use of

torque motors in this industry, in which way manual adjustment is required, leading to inconvenient operation.

Moreover, long-time operation may lead to high temperature of the torque motor, easy damage of controllers and low reliability. This article introduces a kind of constant tension control system for winding of the film blowing

machine integrated with SUNFAR V260 inverters, which can dramatically increase operation simplification and

reliability while ensuring winding process.
   
Introduction of wining process of film blowing machines
1.Constant tension must be maintained over the winding process without the support of manual adjustment.
The tension should not be too high at the time of winding-free start to prevent films from wrinkling; and the

tension should not be too low at the time of full-load operation to prevent film winding from getting too loose.
2.The system responds sensitively, and can make rapid adjustment according to change of preceding-stage speed and

tension during acceleration and deceleration so as to maintain constant tension.
3.The tension should be quantified, so as to set tension value according to process requirements for producing

different films.
  Below control system is designed by use of V260 inverters according to aforesaid requirements.

Control scheme
    As shown in Figure 1, the constant tension is controlled and maintained in following way: the tension sensor in the system outputs voltage signal feedback to the PID control system of the inverter for automatic calculation, and then the inverter changes output frequency to adjust running speed of the winding motor. In fact, it is a kind of direct tension control mode, because PID adjustment is based on the feedback values of the tension sensor, and its feedback values directly reflects the tension degree during winding process. Hence, constant control of tension can be achieved. 

 

System functional block diagram, wiring diagram and control principle description
The system functional block diagram is shown in Figure 2.

 The system wiring diagram is shown in Figure 3.

The system adopts closed-loop vector mode and takes PID output as torque set value. The feedback signal given by the tension sensor is connected to analog AI1 (0-10V) to set desired tension value as PID set value as per the percentage. During system operation, the feedback signal is always compared with set values, and the PID controller automatically calculates according to the difference. Then, the output torque of motors is determined based on PID output value. Hence, the inverter’s output frequency can be changed so as to adjust the winding motor’s revolution and ensure constant tension of films during winding.

Inverter Parameter Setting Table

 

Conclusion
This article introduces a kind of contact-tension winding control system based on SUNFAR V260 vector inverters,

which can keep film tension stable during winding process and make automatic adjustment according to preceding-stage speed and change of tension during winding. In addition, it can also enable stable shifting among machines with multiple winding systems. The entire system operates stables and reliably and has been successfully applied in many film blowing winding systems.

 

References:
User Manual of V260 Series High-Performance Vector Inverters of Shenzhen SUNFAR Electric Technologies Co., Ltd