The choice of paper roll type is based on the type of machine, speed, degree of automation, and the way of receiving paper.
According to the number of paper rolls
1) Single paper roll, one paper feeder can only be on one paper roll. After the paper roll is used up, stop the second paper roll, manually take the paper after the roll paper is good, and then start printing. This type of paper feeder stops the machine every time a paper roll is used, and is therefore generally used on machines that are not very fast. It is no longer used on modern gravure machines.
2) Double paper rolls, one paper feeder can have two paper rolls at the same time. The double paper roll can be divided into two paper arm rotary paper change ways. The upper one paper roll is used first, and the next paper roll is ready for use during use. After the first paper roll is used up, it can be stopped manually or it can be automatically accessed without stopping. After the paper is connected, the second paper roll is transferred to the working position for use. The original first paper-making mechanism is turned to the upper paper position, the old paper roll is removed, and a new paper roll is put on standby. Two rolls on one holder, two rolls on one holder. The holder of the paper feeder cannot be rotated. After using a paper roll to connect the paper tape, the used paper core is hung by a lifting device, and the new paper roll is lifted and mounted. The feeder of this paper feeder can also have automatic take-up and manual take-up. Two separate scrolls, two separate scrolls. Generally used for double paper roll double paper web offset press. That is, two tapes are printed at the same time, and two paper rolls are used at the same time. After the two paper rolls are used up, two paper rolls are stopped at the same time. If used on a single paper path web offset press, one paper roll can be used, and the other paper roll can be put on standby to reduce downtime and improve machine utilization.
3) Three paper rolls, when a paper roll is nearly used up, the paper holder rotates at an angle so that the second paper roll enters the automatic paper receiving position. When the first paper roll is used for the specified size, it will automatically take over the paper. After the paper is fed, it will be rotated at an angle. The second paper roll will be turned to the correct use position. The first paper roll arm will be turned to the loading and unloading paper roll position. The used paper core is then loaded with a roll of paper.
Paper clamping method
The method of clamping the paper roll paper can be divided into two kinds: no-mandrel loading and mandrel loading. According to the degree of automation, it can be divided into manual and electric loading.
1. Core paper holder
Taking a domestic JJ201 web press as an example, the paper feed mandrel is a long optical axis with a thread at one end. It is threaded into the core of the paper roll to be printed, and the top is fixed on the shaft according to the width of the paper roll. Clamp the top.
2. Coreless paper holder
The coreless paper roll holder uses two conical heads to clamp the material roll, and adjusts the screw shaft to move axially along with the bracket to clamp the material from both sides.
Replace the roll method
Web rotary printing presses are high-speed printing presses. Usually, a roll of paper can be printed in 15 to 20 minutes. If the roll is replaced by a stoppage, the production efficiency of the machine will be greatly reduced. At the same time, the normal operation of the machine is disrupted and the operation is damaged. The state of the printing work, resulting in inconsistent quality of the printed matter, or even waste, each time the loss of tape up to 20-30 meters, so it is best to replace the roll during the operation of the machine, pick up the tape, at this time the tape Consumption can be reduced to 3-5 meters.
1. High speed picking
The high-speed automatic picking device refers to an automatic picking device that completes the sticking of the material roll and the replacement of the material roll in the running state of the material roll at full speed or slightly reduced speed. The entire process of replacing the coils and picking up the following process actions:
When the diameter of the coil being used is reduced to a certain degree, the first picking signal is sent out by the monitoring device, the main machine decelerates slightly or does not decelerate, and the drive device of the feed rack 1 will put the new and old material into the joint. Position, so that the old coil material being transported passes through the circumferential surface of the new material roll, and the loading paper holder brush and the material feeder of the blanking knife hem down to the receiving position, which is the connection material. be prepared.
Accelerating a new roll from the drive of the roll is the surface speed of the new roll equal to the linear speed of the original roll being printed.
When the old material roll is consumed to the predetermined minimum size, the monitoring device sends out the second picking signal, the splicing brush immediately presses the running material roll to the surface of the new material roll, and the double-sided tape of the new material roll paper tape head After the two tapes are connected together, the new tape roll is forwarded and the new roll begins to unwind. About 1 second later, the cutting knife on the receiving shelf cuts off the old roll, and the old roll and the new roll are connected. The material process is completed.
The reel rack rotates to the normal working position, and the material roll normally starts to feed. During this time, the old reel can be unloaded and the next new reel can be installed.
2. Zero speed picking
The so-called zero-speed connection refers to the completion of bonding of the material roll at a stationary state, and the machine is still operating normally at high speed. During this period, the feeding material from the feeder, the stocker, supplies the printing material to the printing press. band. Zero-speed picking is characterized by a stocker consisting of a series of lead sticks for stock strips, a fixed and movable stock rack.
The stocker's active stick stocker is lowered to its lowest position, and then the stocker is put on and the active stocker is raised to the working position. This puts it in place and deposits the required stock and the machine is operating normally. During the operation of the machine, a new roll preparation is completed. During this process, the machine runs normally. The required roll is extracted from the hopper, and the movable rack is lowered accordingly. And keep the tension of the material roll unchanged. After the bonding is completed, the movable storage rack is lifted to the working position. At this time, the reel is pulled by the material to accelerate the reel to the opening working speed.
3. Cutting when changing the roll
The cutting of the replacement roll was after the monitor had sent a signal for the second time. This was the state that the old roll had been nearly used up, and the new roll had also been accelerated to the speed required for normal printing of the printing press. At this moment, the axis where the cutter is located is rotated by a certain angle under the drive of the cylinder to complete the cutting work of the old material roll.
