Packaging efficiency and product hygiene control, soft packaging products will be wrapped in a film more frequently. Also, on the soft packaging production line, processed semi-finished products are in volume form.
However, it is rare to see a special discussion on the issue of rewinding. In addition, there were some difficulties with the volume due to experience.
1.Winding tension control mode
(1) Constant tension control mode
The tension remains constant throughout the process.
When the tension set value is small, there will be unwinding; When the tension setting value is large, a large contraction force is formed after winding due to the residual tension of each layer of the film, leaving a transverse dent in the film surface, forming a “chrysanthemum petal” type winding end surface.
(2) Equal torque tension control mode
T = TR
T = T/R
The torque remains constant during the winding process. The tension does not decrease as the diameter of the film coil increases. This is an improvement on the relatively constant tension control, but it is still not very effective.
(3) Gradient tension control mode
The tension decreases with an increase in the diameter of the film coil.
TX=TS[1- (φX-φmin) / (φmax-φmin)KT];
Where TX is the winding tension when the winding diameter is X;
TS is the automatic tension setting value;
KT is the gradient tension set value (%);
φX is the current winding diameter;
φmin is the minimum winding diameter, that is, the paper core diameter;
φmax is the maximum winding diameter.
Setting the gradient KT and the automatic tension setting value TS has a profound effect on the winding effect. At a certain TS, the gradient KT is set too large, and the tension decreases too quickly.
On the contrary, if the gradient KT is set too small and the tension decreases too slowly, the residual tension existing in each layer of the film after winding will form a large contraction force, and eventually form a transverse dent in the film surface.
The set value of gradient KT still needs to be studied. Some of our devices have gradient tension curves, so in practice, it’s important to figure out how to choose the appropriate gradient tension curve.
2.The performance of the retracement problem
(1) Difficulty in winding
Rewinding is difficult and results in incomplete rewinding or even small rewinding, which results in the loss of materials, working hours, and manpower.
Although this problem is serious but can be found immediately, basically within the scope of the correction, it is generally not a great loss of a class of problems.
(2) Problems that can only be found after the process.
In general, the pre-process production of automatic packaging cursor spacing is within the control range. However, after a certain amount of time under certain conditions, the cursor spacing exception is automatically wrapped.
For example, a product’s BOPP/INK/PE structure, the detection of machine composite, and automatic packaging cursor spacing are within the control ranges. However, after a certain period of maturation, the cursor spacing was found to be seriously out of tolerance during slitting.
In addition, liquid milk automatically packaged PE roll film, cutting found that the surface of the roll and close to the core of the cursor spacing difference, and even the core of the cursor spacing error.
Both of these problems are more serious because by the time they’re discovered, the die is cast and they’re probably all junk.
What’s worse, when the reason cannot be found, many people are likely considered to be not serious work, by the unexplainable punishment, that is, the uncontrollability of the way in the control of the volume.
From the perspective of operation, we found that the larger the volume diameter, the more significant the difference between the cursor spacing at the outermost and near the core of the volume.
It is important to pay attention to which products we want to study. The reason for this is how big the maximum diameter of the corresponding equipment is, and what kind of winding equipment should be used.
3.Retractable problem and root cause
(1) Lack of strong technical support in the production and operation of flexible packaging.
Unless the operator is clear about the related material winding tension control factors, it can only experiment, which makes it difficult to maintain stable winding quality.
Due to the lack of theoretical guidance, standard operating procedures (SOPs) cannot be formed. As a result, winding products fail or are unstable, and production efficiency is difficult to improve.
(2) Lack of winding-up technology and equipment
In terms of soft packaging management, there is a lack of systematic technical support for volume collection. Generally speaking, a product often corresponds to multiple materials and multiple machines.
Presently, many manufacturers are trying to process through general equipment. However, if the flexible packaging production management team does not know winding-up technology and equipment winding-up characteristics, then it will be difficult to control the winding-up, which may have to be paid a certain fee.
4.Suggestions for volume collection and problem control
(1) Updated equipment
The learning and training of roll theory should be able to follow the introduction of updated equipment.
(2) Standard operating procedure
For the development of products, the process shall include the study of roll quality control and the drafting of corresponding Standard Operating Procedures.
(3) Routine maintenance and inspections
The operator should conduct routine maintenance and inspections every day to minimize the possibility of hardware or software malfunctions, or at least to prevent the waste of semi-finished products, as materials are relatively expensive.