Introduction to the time relationship of offset press and its adjustment
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First, the relationship between the relationship and time
The paper goes through the series of transfer and 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 end of the first paper feed roller 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 movement time of the front gauge, the movement time of the side gauge, and the movement time of the feeder.
The 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, and feeder failure. 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 separation nozzle, the time relationship between the separation nozzle and the transfer nozzle, the time relationship between the transfer nozzle and the front stop, and the timing of the transfer nozzle and the guide roller. Relationship, etc., wherein only the action time of the front paper stop and the paper guide wheel is adjustable, and the movement time of other mechanical parts is not adjustable.
The main machine movement time requirements of Feida are as follows: 1 When the loose paper mouthpiece stops blowing, 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 absorb 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 nozzle can be delivered and the presser foot is required to reset the paper stopper before the paper. 6 After the paper guide roller presses the paper, the paper feeder can put the paper. When the machine is aging and the paper feed speed is lower than the paper feed speed of the paper guide roller, the paper feed nozzle should be placed first, then the paper guide roller is connected to the paper.
Feida's main time relationship problems are as follows: 1 The presser foot often step on the paper and cause 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, it should be ensured that the presser foot allows the paper control time to be connected with the rotating shaft before the paper is sucked by the paper separating nozzle. To adjust, remove the cam and the rotating shaft to re-align the positioning pin hole or use the set screw. fixed. 2 Distributing the air valve groove 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 separation nozzle has not been released, 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 are not suitable for operation time. Generally, it is easier to adjust the movement time of the paper guide roller or paper stopper. 4 The J2108 and other northern offset printing machine loose paper blowing nozzles have not stopped blowing when the paper separating nozzles are sucking paper, which often causes the paper to be blown or the paper to be sucked up to cause empty sheets and double sheets. In addition to improving the valve air path, there are other problems with poor time relationship, 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 weeks = ∣t before -t ∣ t Before 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 time relationship 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 pass closing 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 not enough, and it is easy to produce paper incomplete overprinting. The solution is to adjust the time between the pre-regulation and Feida.
3, delivery device time relationship
The function of the transfer device is to transfer the stationary positioned paper to the roller biting paper. The main transfer relationship is: the transfer of the transfer paper at the front gauge, the transfer of the transfer paper and the roller bite.
Handover relationship of the paper teeth at the front gauge
1 Positional relationship requirements: The height of the upper pendulum type paper pad is the same and the paper thickness is +0.3mm from the tooth table. The tooth piece is lower than the tooth table and the tooth piece does not touch the tooth table. The height of the hem-type transfer paper tooth pad should be the same and the same as the tooth table. The tooth pad is neither higher than the tooth table nor lower than the tooth table. The gap between the front plate and the tooth plate is +0.3mm, before and after the front gauge. The position allows the transfer paper to bite the paper 5-6mm. 2 time relationship requirements: the paper should be bitten in the static (static to the principle of static paper), after the bite paper, the pull gauge should let the paper, and the pull gauge let the paper (over 3 ° -5 °) after the front gauge Paper, the current rule of paper (5 °-8 °) after the transfer paper should be fed away (handing paper) transfer paper and the paper bite paper transfer relationship (the same relationship between the drum bite paper) 1 positional relationship requirement: at the junction point, the distance between the paper pad and the surface of the roller is +0.3mm, the distance between the transfer paper and the edge of the roller is 1mm, that is, the tooth does not touch the roller; 2 time relationship requirement: handover Point on the tangent point (cut point is the closest point to the surface of the transfer paper pad and the drum surface); around the cut point, the transfer paper and the roller bite should bite the paper together and feed the paper 3-5mm.
Third, the adjustment of time relationship
1. Sequence characteristics of handover relationship adjustment
Adjusting the transfer relationship of the machine must pay attention to the order of precedence, which machine should be adjusted first, and which machine should be adjusted in mind, otherwise it will not adjust the handover relationship, and even further mess up the handover relationship. The adjustment order of the handover relationship is generally consistent with the machine transmission sequence, that is, the power input stage mechanism is first adjusted, and the power output stage mechanism is adjusted later. When adjusting, the output stage mechanism should be adjusted based on the input stage mechanism, and Then change the position and time relationship of the input stage mechanism.
2, offset printing machine main handover relationship adjustment order
The main transfer relationship of the offset printing machine refers to the reference roller and the transfer paper, the transfer paper and the front gauge, the transfer paper and the tooth table, the transfer paper and the pull gauge, the transfer relationship between the front gauge and the paper feeding device, and the adjustment sequence As follows: 1 adjust the reference roller to bite the paper closing time; 2 adjust the paper teeth at the intersection with the roller; 3 adjust the delivery time of the paper at the front gauge and the closing time; 4 adjustment Height of the table; 5 adjust the height and position of the front gauge; 6 adjust the paper time of the front gauge; 7 adjust the paper time of the pull gauge; 8 adjust the action time of the paper feeding device.
3, the common method of time relationship adjustment
General method of time adjustment: 1 Adjusting the movement time of the machine is mostly realized by changing the position of the control cam. The adjustment method is as follows: hand crank the machine to the specified degree, then release the control cam fixing screw to let the control cam (opening the teeth) The plate can be fixed after the light contact with the roller (opening ball); 2 some machine time adjustment is achieved by changing the circumferential position of the transmission gear. The adjustment method is as follows: first hand crank the machine to the specified position, Then check whether the time scale meets the requirements. If the requirements are not met, loosen the fixing screws on the gears (for adjusting the time), and then shake the machine (note that the adjusted parts cannot move) to the specified scale and tighten the screws.
How to determine the intersection point of the roller biting paper and the transfer paper tooth: When the machine is old and aging, the relationship between the machine scale and time is not necessarily correct and reliable, how to determine the cut point? We know that the cutting point is the closest point between the paper pad and the surface of the roller. Therefore, the cutting point can be tested by the feeler gauge. Generally, the offsetting machine sets the cutting time as the zero point of the whole machine, so it should be zero after finding the cutting point. Scale, then adjust the time relationship of other parts according to the time relationship table of the manual.
The method for adjusting the relationship between the paper feeding device and the front gauge: When the machine installation or the Feida repair causes the paper feeding device to have a long time difference between the delivery time and the pre-regulation, the following method can be used to quickly adjust the handover time relationship: firstly, the paper feeding is started. The air pump, then the punctual machine allows the Feida to feed slowly. When the paper is transported to the position of 6-10mm from the front position, it stops jogging, loosens the time adjustment screw, and then aligns the machine. When the current gauge reaches the positioning position, it stops moving. Install the time adjustment fixing screw, and then check the machine to see if it is suitable. If it is not suitable, then fine-tune it.
4, J2205, J2108 offset press time relationship adjustment example
The adjustment sequence is as follows: (1) Adjust the roller biting paper and the paper feeding teeth so that the opening angle is the same, the biting force is consistent; (2) The hand cranking machine detects the start and stop time of the paper feeding mechanism and the backing (the roller and the cam are separated from the start and end time), and adjusts The backing screw is allowed to stop for a duration equal to 27° (25°-30°). (3) The machine test pulls the paper pull duration, adjusts the axial position of the pull groove groove cam (or fine-tunes the roller eccentric shaft) so that the paper pull duration is equal to 40°. (4) Before the machine detects the paper jam time (the difference between the time when the front gauge reaches the positioning position and the paper gauge time), adjust the double nut on the connecting rod so that the paper blocking time is equal to 85°. (5) Determine the zero point of the whole machine: measure with the feeler gauge, and calibrate the dial, then adjust the opening plate to let the roller bite the paper to close the teeth. (6) Shake the machine to zero degree, adjust the gap between the paper pad and the impression cylinder to a paper thickness of +0.3mm (the first flat pad makes the base consistent). (7) Shake the machine to 359° to let the paper teeth open. (8) Shake the machine to 77° to allow the paper to close the teeth. (9) Shake the machine to 74° and let the front gauge let the paper. (10) Shake the machine to 76°, adjust the time of the puller drive gear to let it release paper. (11) Feida passes the paper to the front gauge time, making it equal to 148°. (12) Shake the machine to 90° and let the chain teeth close. (13) Shake the machine to 88° and let the big teeth open. (14) Other time adjustments.