Offset time relationship and its adjustment

First, the transfer relationship and the time relationship between the paper from the fly to the paper delivery station to go through a series of transfer and transfer process, the transfer of the relationship between the paper is from one machine to another machine when the time and location, time is also called mobility The relationship refers to the relative positional relationship between the movements of the moving parts. Therefore, the time relationship is generally expressed by an angle, and one working cycle is defined as 360°. In order to measure the time relationship with the recording mechanism, a 360° scale disc is generally used to fix the end of the reference drum on the offset press. For example: J2108, J2205 impression cylinder, multi-color machine is usually equipped with a dial on the end face of the first contact roller.
In the offset printing press, there are certain time relations among the moving parts from the same power source. Many of the moving parts of the machine are not adjustable. Only a few parts can be adjusted, and the adjustable main parts are adjustable. There are: teeth opening and closing teeth time, paper delivery device delivery time, the former regulatory action time, side gauge action time, Feida action time.

The time relationship is one of the important contents of the offset printing press. The most serious time-related relationship causes the parts to conflict, collide or even damage the parts. The time relationship is mainly related to paper positioning, feeder feeding, and the normal transfer of paper between teeth. The common problems caused by improper time relations are: overprinting, ghosting, bad edges, falling paper, feeder failure, etc. Therefore, it is of great significance to correctly use and adjust the relationship between offset printing presses.
Second, the main time relations and requirements 1, Feida time relationship Feida time relationship mainly between the presser foot and the separation nozzle time relationship, the relationship between the separation nozzle and the delivery nozzle time, delivery nozzle and paper stopper Time relationship, feeding paper nozzle and paper guide roller time relationship, among which only the front paper stopper and guide roller action time is adjustable, the other parts of the action time is not adjustable.
Feida main parts movement time requirements are as follows: 1 loose paper blowing mouth stops blowing, the paper suction nozzle should be moved to the lowest point and start inhaling. 2 The presser foot can be pressed down when the pick-up nozzle is moved up to the highest point. The 3-minute paper suction nozzle and the delivery paper suction nozzle should be able to draw paper together (2° to 5°). After the 4-point suction nozzle stops suction (should be over 2°), the delivery nozzle can deliver the paper.
5 The paper feed nozzle can only feed paper when the paper stopper is swinging forward, and the paper stopper should be reset before the presser foot is allowed to hold the paper. 6 The paper guide roller can hold the paper after the paper feed nozzle is pressed. When the machine is aged and the paper feed speed is less than the feed speed of the paper guide roller, the paper feed nozzle should first release the paper, and then the paper guide roller can take the paper.
Feida's main time-related issues are the following: 1 The presser foot often steps on paper and creates a blank sheet failure. When the suction value of the paper suction nozzle is too small, the paper separation nozzle is too high from the paper surface or the presser foot presses too early, and the paper foot phenomenon that the presser foot steps on the paper dispensing nozzle may occur, and as a result, empty sheets often occur. If you find that the presser foot pressure is too early, you can slow down the presser foot press time, generally about 5 ° slower can greatly improve the reliability of paper separation. However, it should be ensured that the presser foot allows the paper time before the paper is sucked by the paper separator. The presser foot control cam is connected with the rotating shaft by a pin. To adjust, the cam is to be removed and the rotating shaft is re-aligned with the positioning pin hole, or the set screw is used. fixed. 2 Distributing air valve air groove is blocked by paper dust and paper hair, which causes the suction time to change and the paper feeding nozzle does not absorb paper, but when the paper feed nozzle has been discharged or the paper is delivered by the delivery nozzle, the paper dispensing nozzle has not been released. Paper phenomenon. Generally remove the distribution valve after cleaning can be resolved. 3 The guide roller or stopper and other parts are not suitable for the operation time. Adjust the guide roller or the stopper to adjust the operation time. It is relatively easy to implement.
4 J2108 and other North offset presses for loose paper blowing nozzles have not yet stopped when the paper is sucked by the paper suction nozzle, often resulting in blown paper or blown down papers, resulting in empty sheets and double sheets. In addition to improving the gas valve to solve the problem, there are other problems related to the existence of poor time, which is the main reason for the Beiren offset press instability.
2. Positioning device time relationship The function of the resident device is to stop the paper sent from the paper feeding device and accurately position it. The time relationship of the positioning device directly affects the positioning performance of the paper, and has important significance for the Zhang and Zhang overprinting. The main time relationships are:
Paper's circumferential positioning time (t week), paper's axis positioning time (t axis)
t weeks = ∣ t before - t ∣ ∣ t is the time just before the gauge reaches the stop position, and t is the pull gauge time.
T axis = ∣t pull -t let ∣t let pull gauge just let the paper time t generally be more than 40 ° week to ensure good paper circumferential positioning, overprinting accuracy, t axis should be greater than 40 ° to ensure that the paper axial positioning Accurate overprinting. However, with the increase of printing speed, the absolute positioning time of t-axis and t-axis is relatively reduced, and the positioning performance of paper will be reduced. Occasionally, inaccuracy of the gauge will occur.
Positioning device time relationship FAQ: 1t axis is too large, t week is too small, even the paper just came to the front gauge, pull gauge began to pull the paper phenomenon, naturally, such a rule will be very poor, the solution is generally adjusted pull gauge Pull the paper's duration (t axis) and the pull gauge just let the paper time (t let) first adjust the t-axis = 40°, and then adjust t let = hand-off time.
2 Paper is not suitable for the time before the gauge. General requirements When the front gauge has just reached the paper positioning position, the paper should be 6 to 10mm away from the front gauge (front swing type front gauge). If it is too early, the paper tends to overshoot, which often leads to overprinting of the paper. If it is too late, the paper Insufficient positioning time in the circumferential direction, it is easy to produce incomplete paper overprinting. The solution usually regulates the transfer time between the former gauge and feeder.
3, the transfer device time relationship The role of the transfer device is to transfer the stationary positioning of the paper to the roller bite teeth, the main transfer of the relationship are: the transfer of paper teeth at the front of the transfer, delivery paper and roller biting paper Teeth transfer.
The transfer of the paper teeth in the front of the regulation of the relationship between the requirements of a position: the height of the toilet paper pad is consistent and the distance from the tooth plate is +0.3mm, the tooth is lower than the tooth table, the tooth does not touch the tooth table. The height of the hem-handling tooth pad should be the same and the same with the tooth table. The tooth pad is not higher than the tooth table and not lower than the tooth table. The gap between the front guide paper and the table is +0.3 mm. The position allows the delivery paper to bite paper 5-6mm. 2 time requirements: paper handing teeth should be bitten paper in the static (static on the principle of static paper), after the bite paper pull rules should make paper, and pull the rules to let the paper (over 3 ° -5 °) after the former rule to let Paper, the current regulation paper (5°-8°) after the delivery paper should be fed paper (delivery paper) delivery paper and roller teeth bite the intersection of the relationship (the transfer between the roller biting paper the same relationship) 1 position relationship requirements : At the point of delivery, the distance between the paper handing pad and the drum surface is +0.3 mm paper thickness, and the distance between the paper handing tooth piece and the drum lip is 1 mm, ie, the tooth chip does not touch the drum; 2 Time requirement: The junction point is at the cut point Upper (cutting point is the closest point between the paper pad and the surface of the roller); around the cut point, the paper handing teeth and the roller biting paper teeth should both bite paper and feed 3-5 mm.
Third, the adjustment of the time relationship 1, the transfer of the relationship between the order of the characteristics of the regulation of the transfer of parts must pay attention to the order of priorities, the first adjustment of which parts, after adjusting which parts should know what, otherwise they will not adjust the handover relationship, and even further Confused transfer relations. The adjustment sequence of the transfer relationship is generally consistent with the machine drive sequence, ie, the power input stage components are adjusted first, and the power output stage components are adjusted later. In the adjustment, the output stage components should be adjusted based on the input stage components, and no Then change the adjusted position and time relationship of the input stage components.
2. Major transfer relations of offset presses Adjustment sequence The main transfer relationships of offset presses are the reference drum and the transfer paper, the paper feed and the front guide, the paper feed and the tooth carrier, the paper feed and the pull tab, the front gauge and the feeder. The transfer relationship between them, the adjustment order is as follows: 1 adjust the reference roller biting teeth closed teeth time; 2 adjust the delivery paper teeth at the junction with the roller teeth teeth; 3 adjust the delivery paper teeth at the front gauge at the delivery of paper delivery Paper time and closing time; 4 Adjust the height of the dental table; 5 Adjust the height and position of the front gauge; 6 Adjust the time before the paper is adjusted; 7 Adjust the length of the pull paper; 8 Adjust the operation time of the paper feeding device.
3, the time relationship adjustment commonly used methods of time adjustment General methods: 1 adjust the mechanical action time is mostly achieved by changing the control cam position, this adjustment method is as follows: Hand crank the machine to a specified degree, and then release the control cam fixing screw Let the control cam (open tooth plate) and the roller (open tooth ball) touch the fixed cam after light contact; 2 some mechanical time adjustment is achieved by changing the circumferential position of the transmission gear, this adjustment method is as follows: First hand-crank the machine to the designated position, then watch if the time scale meets the requirements. If it does not meet the requirements, loosen the fixing screw on the gear (for adjusting the time), and then hand-crank the machine (note that the adjustable part cannot be moved) to the specified Tighten the screws after the scale.
How to determine the contact point between the roller teeth and the delivery tooth: When the machine is out of date and the relationship between the machine scale and the time is not correct and reliable, how to determine the cut point? We know that the point of cut is the closest point between the paper pad and the drum surface. Therefore, the cut point can be determined by the feeler. Generally, the offset machine sets the cut time as the zero point of the whole machine. Therefore, the zero should be found after finding the cut point. Scale, and then can adjust other parts of the time relationship according to the specification time relation table.
The adjustment method for the relationship between the paper feeding device and the front gauge time: when the machine installation or feeder repair causes the paper feeder to be far away from the timing of the front gauge, the following method can be used to quickly adjust the relationship between the paper handling device and the front gauge: The paper must be opened first. Air pump, then the punctual machine allows Feder to feed paper slowly. When the paper is transported to the position 6-10mm away from the previous specified position, stop the jogging, loosen the time adjustment screw, and then point the machine. When the current gauge just reaches the positioning position, stop the jog , Put on the time adjustment fixing screw, and then check if the machine is suitable for paper feeding. If it is not suitable, then fine-tune it.
4, J2205, J2108 offset press time adjustment example adjustment order is as follows: (1) adjustment roller bite paper teeth and paper handing teeth, so that its consistent Zhang Jiao, bite force the same; (2) Hand crank machine detection paper delivery agencies and stop by the start and end time ( Roller and cam disengaged start and end time), adjusting the back screw, so that the stop duration is equal to 27 ° (25 ° -30 ° can be). (3) Shake the machine to pull the pull gauge for the duration of the pull, adjust the axial position of the pull gauge groove cam (or fine-tune the roller eccentric shaft) so that the draw duration is equal to 40°. (4) Check the front regulation paper time (the difference between the time when the front gauge just reached the positioning position and the front gauge paper timing) and adjust the double nuts on the connecting rod so that the blocking time is equal to 85°. (5) Determine the zero point of the machine: Measure and confirm with the feeler gauge, and calibrate the dial, then adjust the open tooth plate to make the roller bite the teeth. (6) Shake the machine to zero degree, and adjust the gap between the transfer paper pad and the impression cylinder to a paper thickness of +0.3 mm (the first flat pad will make the base consistent). (7) Shake the machine to 359° so that the paper hand teeth are opened. (8) Turn the machine to 77° to allow the paper to be closed. (9) Shake the machine to 74° and let the front gauge make paper. (10) Turn the machine to 76° and adjust the length of the pull gauge drive gear to allow it to feed. (11) Feida took the paper to the front gauge time and let it equal to 148°. (12) Shake the machine to 90° to allow the chain teeth to close. (13) Shake the machine to 88° to allow the teeth to open. (14) Other time adjustments.