Offset machine time relationship and its adjustment (on)
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First, the relationship between the relationship and time
The paper goes through the series of transfer transfer process from the fly to the delivery table. The transfer relationship refers to the time and position relationship when the paper is handed over from one machine to another. The time relationship is also called the maneuver relationship, which refers to the moving parts. The relative positional relationship between the movements, so the time relationship is generally expressed by angle, and one duty cycle is specified as 360°. In order to measure and time the relationship between the components, a 360° graduated disc is typically attached to the end face of the offset cylinder of the offset press. For example: J2108, J2205 impression cylinder, the first paper feed roller end face of the multicolor machine is generally equipped with a dial.
On the offset printing machine, there is a certain time relationship between the moving parts from the same power source. Many of the movement time of the machine is not adjustable, only a small part of the movement time of the machine is adjustable, and the main adjustment is adjustable. There are: the time of opening and closing the teeth of the paper, the delivery time of the delivery device, the time of the front gauge movement, the movement time of the side gauge, and the movement time of the feeder.
Time relationship is one of the important contents of the offset printing machine. The time relationship is not correct. The most serious situation will cause the parts to collide, collide and even damage the machine. The time relationship is mainly related to the paper positioning, Feida paper feeding, and the normal transfer of paper between the teeth. The common problems caused by improper time are: overprinting, ghosting, biting paper, paper drop in the middle, Feida paper feeding failure, etc. Therefore, it is important to correctly use and adjust the time of the offset press.
Second, the main time relationship and requirements
1. Feida time relationship
The Feida time relationship mainly includes the time relationship between the presser foot and the paper separation nozzle, the time relationship between the paper separation nozzle and the paper feed nozzle, the time relationship between the paper feed nozzle and the front paper stop, the paper feed nozzle and the paper guide roller time. Relationship, etc., only the action time of the front stop and the paper guide wheel is adjustable, and the movement time of other parts is not adjustable.
The main machine movement time requirements of Feida are as follows: 1 When the loose paper mouthpiece is stopped, the paper separation nozzle should be moved down to the lowest point and start to inhale. 2 When the separation nozzle moves up to the highest point, the presser foot can be pressed down. The 3-part paper nozzle and the paper-feeding nozzle should be able to suck paper together (2° to 5°). After 4 minutes of paper suction nozzle is stopped (2° should be passed), the paper nozzle can be delivered.
When the 5 paper flaps are placed in front of the paper, the paper feed nozzle can be delivered and the presser foot is required to reset the paper stop before the paper stop. 6 After the paper guide roller presses the paper, the paper feeder can put the paper. When the machine is aging and the paper conveying speed is lower than the paper feed speed of the paper guide roller, the paper feed nozzle should first put the paper, and then the paper guide roller is connected to the paper.
Feida's main time relationship problems are as follows: 1 The presser foot often presses on the paper to generate an empty sheet failure. When the suction of the separation nozzle is too small, the separation nozzle is too high from the paper surface or the presser foot is pressed too early, the paper phenomenon of the presser foot stepping on the separation nozzle may occur, and the result is often empty. If it is found that the pressing of the presser foot is too early, the pressing time of the presser foot can be appropriately slowed down, generally about 5° slower to greatly improve the reliability of the paper separation. However, the presser foot should be ensured that the presser foot control cam is connected with the rotating shaft before the paper is sucked by the presser foot. To adjust, remove the cam and the rotating shaft to re-align the pin hole or use the set screw. fixed. 2 Distributing the air valve of the air valve is blocked by the paper ash and the paper hair, causing the change of the inhalation time to occur, and the paper nozzle has not been sucked, and the paper separation nozzle has been discharged or the paper feeder has been delivered. Paper phenomenon. Generally, the distribution valve can be removed and cleaned. 3 Guide roller or paper stopper and other parts of the action time is not suitable, generally adjust the paper guide roller or paper stop action time, it is easier to achieve.
4 J2108 and other northern offset printing machine loose paper blowing nozzles in the paper suction nozzle when the paper is not blowing, often causing blowing paper or blowing down the paper phenomenon, resulting in empty sheets, double failure. Improve the valve air circuit to solve. In addition to this, there are other problems with poor time relations, which is the main reason for the instability of paper feeding in Beiren offset presses.
2, positioning device time relationship
The function of the holding device is to freeze the paper fed from the paper feeding device and accurately position it. The time relationship of the positioning device directly affects the paper positioning performance, which is of great significance for the sheet and the sleeve printing. The main time relationships are:
Paper circumferential positioning time (t weeks), paper axis positioning time (t-axis)
t week = ∣t before -t ∣ ∣ t is the time when the front gauge has just reached the paper stop position, t is the pull gauge just pulled paper time.
T axis = ∣t pull -t let ∣ t let the pull gauge just let paper time
Generally, the t-week is greater than 40° to ensure good circumferential orientation of the paper, and the overprinting is accurate. The t-axis should be greater than 40° to ensure good axial positioning of the paper and accurate overprinting. However, as the printing speed increases, the absolute positioning time of the t-week and the t-axis is relatively reduced, and the positioning performance of the paper is degraded, so that the irregularity of the sleeve is occasionally generated.
Frequently asked questions about the positioning time of the positioning device: 1t axis is too large, t week is too small, even when the paper just comes to the front gauge, the pull gauge starts to pull the paper. Naturally, the gauge will be very poor. The solution is generally to adjust the pull gauge. The paper pull duration (t-axis) and the pull gauge just let the paper time (t let) first adjust the t-axis = 40 °, and then adjust t to let the paper-tooth stop time.
2 The paper is not suitable for the pre-regulation time. Generally, when the front gauge has just reached the position of the paper stop, the paper should be 6~10mm away from the front gauge (upward swing type front gauge). If it is too early, the paper is too easy to overturn, and the paper is too late to overprint, such as too late, paper The circumferential positioning time is insufficient, and it is easy to produce paper incomplete overprinting. The solution is to adjust the time between the pre-regulation and Feida.