Application of VEICHI AC200T In Offset Press

Project Overview

Overview

The main movement characteristics of printing machinery: a variety of flexible materials as manufacturing objects. During the process, it not only needs to ensure the movement of printing materials according to the requirements, but also needs to complete the printing of various colors or the processing of substrate.Thus, two kinematic chains of paper movement and printing movement of printing machinery are produced, which are mutually coordinated. Taking offset press as an example, to ensure the speed regulation and printing, many of the equipmentsare still using DC speed regulation driving mode to control the two kinematic chains.In order to complete the printing production, there are many movementsthat need to complete: to ensure the jog operation (loading plate, cleaning drum, threading paper) process requirements,coaxial with DC motor and with a set of AC motor and cycloid reducer to meet the low-speed jog operation.In addition, there is a direct relationship between the supply of water and ink and printing speedin the printing process, therefore, the water and ink rollers are driven by two DC servo motors separately. There are also some other motors with constant speed transmission,being responsible for the adjustmentofprinting cylinder and position of paper loading and roller.In order to ensure the printing quality, it needs the magnetic powder brake to control tension, needsthe measuring motor to guide ink supply, needs the offset device to control paper route, and needs some othermotor with different forms in these mechanisms.

Process Requirements

The main products of intermittent offsetpress are trademarks and labels, which has high requirements of tension accuracy.Mainly reflecting in below points:

1. Steady tension control with fluctuation less than 3%;

2. Fast start and fast stop with no impact on printing materials;

3. High speed response of tension.

Why does offset press have above requirements about inverter? Because the winding mode is batch-type, and there is a storage space of materials between traction roller and unwinding roll.The offset press will give the inverter a start signal when the lower limit photoelectric switch senses materials, and unwinding motor will crinkling printing materials.Traction motor will stop when upper limit switch senses printing materials, and the winding motor maintains a constant tension to printing materials. The whole process lasts about 3 seconds, therefore, this situation has high requirements to response speed of tension.

Solution of VEICHI Products

Adopt the advantages of AC200T series inverter

1.Unique automatic calculation function of winding diameter.

With the increasing of winding roller diameter, the inverter output frequency of winding motor will continually decreases. There is a specialized roller diameter calculation function in AC200T series inverter, which could dynamically and automatically calculate the current diameter of winding diameter at real time, so as to achieve the best constant tension winding effect.

2.Constant tension control

With its excellent tension control function, AC200T can adjust the torque output in real-time according to the tension changes on the material, so as to ensure the constant tension on materials.

Conclusion

The offset press system with VEICHI inverter could achieve steady and reliable operation, and gain high economic benefits for customers. And VEICHI overall solution is highly praised by customers through the actual production test. The specific advantages are as below:

1. Easy to adjust wingding tension. The tension and synchronization control are both completed in inverter, which greatly improves the reliability and stability;

2. Adopt VC control. Fast dynamic response,high control accuracy, andconstant tension while ACC/DEC, to avoid color dislocation;

3. Long service life of inverter and easy to use and maintain;

4. No installation of tension sensors and encoder, which saves cost for equipment manufacture.