Trouble shooting of Heidelberg K series offset pre

2022-07-24
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Heidelberg K series offset printing machine fault and troubleshooting (Part 2)

② paper receiving transmission instability

a, the same as the above example ⑤

b, the imprinted solid ground can be used to culture the cells and tissues in the body. The ink layer is thick, resulting in a large force when the printing sheet peels off the rubber cylinder When the tail of the paper is still being printed, the impression cylinder has delivered the paper to the receiving row teeth. Because the movement of the receiving and the drum teeth can not be completely synchronized, especially when the receiving teeth move away from the sprocket for a straight track, the speed is significantly reduced, so that the printing sheet is not tightly wrapped around the impression cylinder, but the printing paper must be attached to the rubber cylinder. After printing, the wet imprint is against the receiving support rod, In addition, without the impression cylinder gripping the paper, it is easy to make the tail of the printing sheet rub dirty, duplicate, wrinkle and roll glue (the printing sheet is rolled on the high-speed rotating rubber cylinder under the action of ink adhesion, and it is estimated that the maximum adhesion force on the 700mm wide printing sheet can reach 70kg), or the tail overprint is inaccurate; It is difficult for users to eliminate the cause of this fault. The root cause is that the machine structure design is unreasonable and the rollers are improperly arranged (only from the aspect of overprint process)

③ the cylinder lining is poor, and the printing pressure is improper

④ the rubber blanket is not tensioned or tilted

Troubleshooting:

① A. repair the left and right fixed guide rails, repair the worn surface, especially the data correction at the upper and lower dead ends of the guide rails. The brush plating method is used for on-site operation and regrinding, which is convenient, fast, labor-saving and material-saving

b. replace the needle roller bearing with a specification of 12x15x10. If it is not available, the roller can be processed instead, and the outer circle is quenched HRC

c. mapping and processing sector gear, or replacing spare parts

d. if Liao 8 taper pin is found shortly after breaking and the shaft is not worn, just take out the broken pin and re drive it into the new pin for positioning; If it is found that the shaft is worn, only brush plating is required to repair the shaft and ream the hole, which can get twice the result with half the effort and avoid the trouble of disassembly and installation. If the bearing fails, domestic 20 bearing can be used instead

② a. the same as the above method ⑤

b. thinning the ink layer, reducing the viscosity, improving the printability of the paper, or considering it from the process and production arrangement. In short, all these are to try to reduce the stripping force of the printing sheet from the rubber drum

c. the fundamental solution is to improve the structural design of the printing machine, so that when the receiving teeth bite the paper, only a small part of the paper tail is still in printing, and the imprinting must be completed before the receiving teeth move in a straight line. A three cylinder equal diameter offset press meets this condition Of course, the large-scale improvement design is only meaningful to the printing machine manufacturer. Besides, K series machine is an early product of Heidelberg company, which is a transitional product from relief to offset. Due to the limited structure, it has to be done

③ properly adjust the printing pressure and cylinder lining according to the process requirements and specific conditions

④ loosen the blanket, smooth the cushion and tighten it evenly

fault 4: the paper receiving tooth row is twisted or broken

cause:

① the spring on the paper supporting roller is invalid, the supporting rod falls and bends, or the paper receiving row is interrupted

② the chain is too loose, the paper receiving tooth row vibrates too much, collides with other parts, or the chain breaks due to fatigue

③ break the fixed shaft pin of the connecting chain of the paper receiving tooth row

elimination of the rapid development of hydraulic technology:

① replace the spring, straighten or replace the paper receiving tooth row, and it can also be mapped and processed

② adjust the center distance of chain wheel, tighten the chain so that it can be lifted 30mm high on the guide rail. If the chain is seriously worn, it can be replaced

③ replace the axle pin, which can be mapped and processed

note: this fault is the most common. Check the supporting rod spring, shaft pin and chain frequently to find the problem early and prevent it

fault 5: the two sides of the teeth of the receiving tray are not equal

cause: the receiving tray seat is not parallel to the drum

Troubleshooting: loosen the connecting screw between the receiving tray seat and the chain plate, and the receiving tray seat on the side with a large bite moves backward, otherwise it moves forward to make it parallel to the drum.

then tighten the screw, and the bite should be 4 ~ 6mm

fault 6: the air pump vibrates violently and periodically

cause: the nut on the end face of the piston in the air pump is loose and bumps into the cylinder head on the inner wall of the air pump after exiting

Troubleshooting: disassemble the air pump and tighten the nut

fault 7: uneven paper receiving

cause:

① the side paper is not working properly

② the position of the paper feeding and tooth opening cam is improperly adjusted

③ low humidity, serious static electricity of the paper, or the paper is too thin

Troubleshooting:

① A. adjust or replace the spring connected with the cam follower to make the flat paper shaft drive normally

b. check the contact between the swing rod roller and the roller on the side baffle, and adjust appropriately

② properly adjust the cam position (paper receiving and discharging CAM) according to the printing speed, paper weight and other factors

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