Analysis of tension control and adjustment device of JJ204 offset press (2)

2. Paper guide roller adjustment

The adjustment of the paper guide roller is divided into two parts: one is a middle seam and the other is a paper edge.

The main function of the mid seam adjustment is to maintain a proper gap with the calculation of the triangle board and ensure that the paper strip smoothly enters the folding machine. For the size of the gap, there is a saying that the paper thickness plus 0.2mm, but I believe that regardless of double paper or single paper, are a 16 book open book thickness is appropriate. Such a gap is neither too large nor too small, it is not easy to cause a break, and it is easy to wear paper, and it is easy to grasp.

The main function of the paper edge adjustment is to adjust the position of the crease of the paper tape. At the same time, it also changes the tension of the paper tape in the seam and the paper edge tension. As the distance between the paper guide rollers is reduced, the tension in the paper edge becomes larger and the tension in the middle seam becomes smaller. On the contrary, the tension in the paper edge becomes smaller and the tension in the middle seam becomes larger. If the adjustment is not good here, it will lead to tape breakage, tearing, etc., so when adjusting, you should pay attention to observe whether the seam is aligned, while carefully listening to the sound of paper with no "Baba" break, combine Triangular board forward and backward comprehensive adjustment.

Tight paper roll

The main function of the tight paper roll is to pull the paper tape, and the vertically folded paper tape is fed into the three-roller folding machine in a balanced manner. In order to enhance the friction of the traction tape, two ends of the paper roll are equipped with a rolling wreath. The adjustment of the tight paper roll includes axial adjustment and radial adjustment.

Axial adjustment is mainly to adjust the relative position of the roll wreath on the shaft, so as to adapt to the width of the paper tape or the change of the position of the print and the graphic text, so that the rolling wreath is pressed on the empty part that does not affect the quality of the printed product.

Radial adjustment is mainly to adjust the pressure of two tight paper rolls on the paper tape. The quality of the radial adjustment will affect the tension change of the tape, too tight, easy to produce a break; too loose, the longitudinal position of the tape is unstable. In the measurement, the thickness of the tape passing between the two tight paper rolls shall be taken as the standard. That is, when a single paper path is used, the thickness of two sheets of paper shall be used as a measurement standard; in the case of a double paper path, the thickness of four sheets of paper shall be used as a measurement standard. The size of the pressure is better to see a slight knurled print.

Because the tight paper roll is a pair of steel rings rolling against each other, it wears fast. When a paper cutter is added to the paper, there is a position where the tape is suddenly taut. Therefore, the wear on the roll wreath is not uniform. Replace it in time.

Common causes of failure

After understanding the above, it is not difficult to understand the causes of a series of process failures caused by improper adjustment of these components.

1. Tape drift

Cause: The tension is too low, the feed speed is too fast, the take-up speed is too slow, or the paper roll is too loose.

2. Double paper tape drift

Cause of failure: The tension of the two tapes is inconsistent, one quick and one slow. At the same time when entering the paper take-up roller, the tension is less likely to drift back and forth.

3. Break or tape tear

Cause: The tension is too high, the feed speed is too slow, the tight paper roll is too tight or the knife is too high.

4. Imprinting is not allowed

Cause of the problem: The tension is too small or too large, resulting in unstable paper handling.

5. The mark is not allowed up and down, like the stock K chart

Cause of the fault: The tension is too great and the resulting page is unstable.

6. Change the needle often

Cause of failure: Large tension.

7. Change the rubber knife pad (commonly known as the rubber band)

Cause of the problem: The tension is small, the paper tension is not tight, or the paper cutting force is too high, resulting in serious wear.

Everything is connected with each other, and the tension of the tape is no exception. The speed of paper feeding is too fast and the force of paper feeding is too small, which will affect the printing, delivery, and folding sections. Therefore, be aware of this when analyzing faults. When adjusting tension control parts, pay attention to the order of adjustment. First adjust the components that have little effect on other aspects and those that can be adjusted in the off state. Specifically speaking, it is the first adjustment of the tight paper roll, the delivery of flowers, the magnetic powder brake, and then adjust the paper guide roll and triangle, and finally adjust the continuously variable transmission. As long as we think and continue to summarize in our work, it is not difficult to solve the problem of tension.