1. Handover relationship and time relationship
The paper passes through a series of handover transfer processes from the fly to the take-up table. The handover relationship refers to the time and position relationship when the paper is handed over from one machine part to another. The time relationship is also called the motor relationship, which refers to the moving machine parts. The relative positional relationship between the movements, so the time relationship is generally expressed in degrees, and a working cycle is specified as 360 °. In order to measure the time relationship with the recording device, a 360 ° scale disc is generally fixed on the end surface of the reference cylinder of the offset printing machine. For example: J2108, J2205 impression cylinder, multi-color machine is generally equipped with a dial on the end surface of the first receiving cylinder.
On the offset press, there is a certain time relationship between the moving parts from the same power source. Among them, many parts are not adjustable, and only a few parts are adjustable. The main adjustable There are: the time for opening and closing the teeth, the time for the paper delivery device, the time for the front gauge action, the time for the side gauge action, and the time for the fly action.
Time relationship is one of the important contents of offset presses. The most serious case of incorrect time relationship will cause conflicts, collisions or even damage to the parts. The time relationship is mainly related to the positioning of the paper, the feeder feed, and the normal handover of the paper between the teeth. Common problems caused by improper time relationship are: inaccurate overprinting, ghosting, biting of the paper edge, paper drop in the middle, and feeder feed failure, etc. Therefore, it is of great significance to correctly use and adjust the time relationship of the offset press.
2. Main time relationship and requirements
1. Feida time relationship
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 delivery nozzle, the time relationship between the delivery nozzle and the front stop tongue, and the time between the delivery nozzle and the paper guide roller Relationship, etc., only the action time of the front stop tongue and the paper guide wheel is adjustable, and the action time of other mechanical parts is not adjustable.
The operation time requirements of the main parts of Feida are as follows: ①When the loose paper blowing nozzle stops blowing, the separation nozzle should move down to the lowest point and start inhaling. ②When the separation nozzle moves up to the highest point, the presser foot can only press down. ③Paper separation nozzle and paper delivery nozzle should be able to absorb paper together (2 ° ～ 5 °). ④After the paper separation nozzle stops sucking (should pass 2 °), the paper delivery nozzle can deliver the paper. ⑤ The paper delivery mouth can only deliver paper when the paper retaining tongue swings forward and the paper retaining tongue should be reset before the presser foot is required to make the paper. ⑥ After the paper guide roller presses the paper, the paper delivery nozzle can put the paper. When the machine is aging and the paper delivery speed is less than the paper feed speed of the paper guide roller, the paper delivery nozzle should put the paper first, and then the paper guide roller receives the paper.
The main timing problems of Feida are as follows: ①The presser foot often steps on the paper and causes a blank sheet failure. When the suction amount of the paper separation nozzle is too small, the paper separation nozzle is too high from the paper surface, or the presser foot is pressed too early, the paper foot will step on the paper of the paper separation nozzle, resulting in empty sheets. If you find that the presser foot is pressed too early, you can appropriately 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 separation nozzle sucks the paper. The presser foot control cam is connected to the rotating shaft with a pin. To adjust, the cam and the rotating shaft are removed to reposition the positioning pin hole or fixed with a stop screw fixed. ②The air path slot of the distribution valve is blocked by paper dust and paper wool, which causes the change of the suction time and the paper delivery nozzle is not sucked and the paper separation nozzle has been placed or the paper delivery nozzle has not been placed. Paper phenomenon. Generally, it can be solved after removing the distribution valve and cleaning. ③ The action time of the paper guide pressure roller or paper blocking tongue is not suitable for other mechanical parts. Generally, it is sufficient to adjust the action time of the paper guide pressure roller or paper blocking tongue, which is relatively easy to realize. ④ J2108 and other Beiren offset printing machine loose paper blowing nozzles have not stopped blowing when the separation nozzle suction paper, often caused the phenomenon of blowing the paper or blowing the paper under the phenomenon of empty and double sheets. Improving the air valve and air path to solve the problem that there are other bad time relationships exists, which is the main reason for the instability of the Beiren offset press.
2. Time relationship of positioning device
The function of the fixing device is to stop the paper sent by the paper feeding device and perform accurate positioning. The time relationship of the positioning device directly affects the positioning performance of the paper, and is of great significance to sheet and sheet overprinting. The main time relations are:
Paper's circumferential positioning time (t-week), paper's axis positioning time (t-axis)
tweek =? tfront-tpull? tfront is the time when the front gauge has just reached the stop position, and tpull is the time when the gauge just pulled the paper.
T axis =? T pull-t let? T let just pull the paper time
Generally, t-period must be greater than 40 ° to ensure good positioning of the paper in the circumferential direction and accurate overprinting, and t-axis must be greater than 40 ° to ensure good positioning of the paper in the axial direction and 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 the paper will be reduced, so occasionally, the phenomenon of inaccuracy of registration will also occur.
Common problems in the time relationship of the positioning device: ①The t axis is too large and the t circumference is too small. Even when the paper reaches the front gauge, the pull gauge starts to pull the paper. Naturally, the set gauge will be very poor. The solution is generally to adjust the pull gauge. The duration of pulling the paper (t axis) and the time just after pulling the gauge (t let) first adjust the t axis = 40 °, and then adjust t let = the tooth closing time. ②The time before the paper arrives is not suitable. Generally, when the front gauge has just reached the position of the paper stop, the paper should be 6 to 10mm away from the front gauge (upper swing front gauge). If it is too early, the paper may be too far, and the paper will often lead to inadequate overprint. If it is too late, the paper Insufficient positioning time in the circumferential direction can easily lead to inaccurate overprinting. The solution is to generally adjust the handover time between the front gauge and Feida.
3. Time relationship of paper delivery device
The function of the paper delivery device is to transfer the statically positioned paper to the roller bite. The main handover relationship is: the delivery of the delivery tooth at the front rule, the delivery of the delivery tooth and the roller bite.
Handover relationship of paper-handed tooth in the front rule
①Requirements for positional relationship: The height of the top-swinging paper pads is the same and the thickness of the paper is + 0.3mm from the tooth table. The dental tablets are lower than the dental table, and the dental tablets do not touch the dental table. The height of the bottom-heavy delivery tooth pads should be the same and the same as the dental table. The dental pad is neither higher than the dental table nor lower than the dental table. The gap between the top stop board and the dental table is + 0.3mm thick. The position allows the delivery teeth to bite the paper 5-6mm. ② Time relationship requirements: The delivery tooth should bite the paper at rest (the principle of static to static paper receiving). After biting, the pull rule should allow the paper, and the pull rule allows the paper (after 3 ° -5 °). Paper, the current regulation paper (5 ° -8 °), the paper delivery teeth should be fed away (paper delivery), the transfer relationship between the delivery teeth and the roller bite (the same relationship between the roller bite) : At the handover point, the distance between the delivery tooth pad and the surface of the drum is paper thickness + 0.3mm, and the distance between the delivery tooth piece and the edge of the drum is 1mm, that is, the tooth piece does not touch the drum; Up (cutting point is the closest point between the delivery tooth pad and the surface of the roller); around the cutting point, the delivery tooth and the roller biting tooth should bite the paper together and walk 3-5mm. [next]
3. Adjustment of time relationship
1. Sequence characteristics of adjustment of handover relationship
It is necessary to pay attention to the order of adjusting the handover relationship of parts, which part should be adjusted first, and which part should be adjusted later, otherwise it will be difficult to adjust the handover relationship, and will even further mess up the handover relationship. The adjustment sequence of the transfer relationship is generally consistent with the machine transmission sequence, that is, the power input stage parts are adjusted first, and then the power output stage parts are adjusted. During the adjustment, the output stage parts should be adjusted based on the input stage parts, and must not be adjusted. Then change the relationship between the adjusted position and time of the input stage mechanism.
2. Adjustment sequence of main handover relationship of offset press
The main handover relationship of the offset press refers to the handover relationship between the reference roller and the paper delivery tooth, the paper delivery tooth and the front gauge, the paper delivery tooth and the tooth table, the paper delivery tooth and the pull gauge, the front rule and the paper conveying device, and the adjustment sequence It is as follows: ①Adjust the closing time of the bite teeth of the reference roller; ②Adjust the tooth opening time of the delivery tooth at the interface with the roller; ③Adjust the delivery time and tooth closing time of the delivery tooth at the front gauge; ④Adjust The height of the tooth table; ⑤Adjust the height and position of the front gauge; ⑥Adjust the time of the front gauge to make the paper; ⑦Adjust the time of the pulling gauge to make the paper; ⑧Adjust the action time of the paper feeding device.
3. Common methods of time relationship adjustment
The general method of time adjustment: â‘ Most of the action time of the machine is adjusted by changing the position of the control cam. This adjustment method is as follows: hand crank the machine to the specified degree, then loosen the control cam fixing screw to let the control cam (open the teeth) Plate) and the roller (opening ball) lightly contact and fix the cam; â‘¡ Some machine parts are adjusted by changing the circumferential position of the transmission gear. This adjustment method is as follows: first hand shake the machine to the specified position, Then watch whether the time scale meets the requirements. If it does not meet the requirements, loosen the fixing screws (for adjusting the time) on the gears, and then hand 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 teeth and paper delivery teeth: when the machine is old and aging, the relationship between the machine scale and the 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 tooth pad and the surface of the roller, so the feeler can be tested to determine the cutting point. Generally, the offset time is set to the zero point of the whole machine, so the zero should be corrected after the cutting point is found. Scale, and then you can adjust the time relationship of other parts according to the time relationship table of the manual.
Method for adjusting the relationship between the paper conveying device and the front gauge time: when the machine installation or feeder repair causes the transfer time between the paper conveying device and the front gauge to be very different, the following method can be used to quickly adjust the relationship between the handover time: Air pump, and then point the machine to let Feida feed the paper at a slow speed. When the paper is fed to 6-10mm from the previous specified position, stop the jog, loosen the time adjustment screw, and then point the machine. When the current gauge has just reached the positioning position, stop the jog , Install the time adjustment fixing screw, and then point the machine to see if the paper is suitable. If it is not suitable, fine-tune it again.
4. J2205, J2108 offset press time relationship adjustment example
The adjustment sequence is as follows: (1) Adjust the roller teeth and paper delivery teeth so that their opening angles are consistent and the bite force is consistent; Backscrew, let the docking duration equal to 27 ° (25 ° -30 ° is acceptable). (3) Test the duration of pulling the paper by shaking the machine, adjust the axial position of the groove cam (or fine-adjust the roller eccentric shaft) to make the pulling time equal to 40 °. ⑷The shaker detects the paper stop time of the front gauge (the difference between the time when the front rule has just reached the positioning position and the paper time of the front rule), and adjusts the double nuts on the connecting rod to make the paper stop time equal to 85 °. ⑸Determine the zero point of the whole machine: use a feeler gauge to determine and calibrate the dial, and then adjust the tooth opening plate to let the roller bite the paper and close the teeth. ⑹ Shake the machine to zero degree, adjust the gap between the surface of the transfer tooth pad and the impression cylinder to the paper thickness + 0.3mm (first flatten the tooth pad to make the base consistent). ⑺Shake the machine to 359 °, let the delivery paper teeth open. ⑻Shake the machine to 77 °, let the delivery paper teeth close. ⑼ Shake the machine to 74 °, let the front rule make the paper. ⑽ Shake the machine to 76 °, adjust the time of the pull gear transmission gear to let it put paper. ⑾Feder feed paper to the pre-regulation time, let it be equal to 148 °. ⑿ Shake the machine to 90 ° to close the chain teeth. ⒀Shake the machine to 88 ° to let the big teeth open their teeth. ⒠Adjust at other times.
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