Analysis of common mechanical faults of single con

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Analysis of common mechanical faults of single concave machine (I)

I. several problems needing attention in printing adjustment

1. When printing, it is customary to print at low speed and then gradually increase the speed like an offset press, which is easy to cause interval error in overprint

2. Due to the problems of ink or printing plate, it is not advisable to blindly use pressure adjustment, and the printing pressure should not be too large

3. Although the adjustment amount of scraper angle is large, the printing effect cannot be adjusted by scraper angle

4. When the plate cylinder (hollow version) passes through the shaft, the keyway should be aligned, and the locking force of the large nut is appropriate

5. After the UV drying system is turned off and then turned on, it will be restarted at an interval of 5 minutes, because there are protective measures in the UV cabinet. If it is turned on and off frequently, it is easy to shorten the service life of the lamp tube and make the drying insufficient

6. The whole machine shall be maintained and lubricated on time

II. Overprint adjustment

for the troublesome problem of inaccurate overprint, the operator can't find the maintenance personnel as soon as there is a problem. First, adjust it by himself. The experienced operator will adjust it in place according to the direction of the line. If you can't judge the problem, you should adjust it from the beginning

1. Starting from the paper feeder, the paper output should be stable and the paper feeding should be correct

2. The kissing time on both sides of the paper receiving wheel is the same, and the strength is balanced and moderate (adjusted according to the thickness of the paper)

3. The paper feeding wheel and the paper feeding rough wheel should also adjust the paper pressing force according to the paper situation and be arranged in order, which is the purpose of accelerating the development of new material industry smoothly and reaching the former regulation neatly

4. When the paper reaches the front gauge, the tangent point of the paper feeding wheel should be pressed at 1mm ~ 2mm (thick paper) at the end of the paper to prevent rebound. For example, for thin paper printing, the tangent point of the paper feeding wheel should be just the same as the weight of the end of the paper to prevent wrinkling

5. The handover time and the drawing time of the side gauge should be adjusted in place. Some operators adjust the drawing time of the side gauge to be consistent with the drawing time of the swing tooth, which is not desirable. It should be clear that after the side gauge pulls the paper in place, the swing tooth picks up the paper, the front gauge lifts up and sends the paper to the embossing drum

6. When adjusting the front gauge, the spring plate shall be adjusted properly. The front end of the spring plate shall be 2mm ~ 3mm away from the bending plate of the front gauge. When the front gauge falls, the contact plate shall be able to contact the copper block on the paper table. If it is not touched, it will not be detected. If the spring plate is adjusted too downward, it will always contact the copper block, which will not meet and press up, and it will always be in the detection state

7. The paper pulling time of the side gauge should be adjusted to not grab the paper with the swinging device or the front gauge, and the paper pulling of the side gauge should be controlled within 5mm ~ 8mm

8. The paper gripping force of the paper gripping teeth of the tooth shaft of the embossing cylinder shall be balanced, and the experimental load shall be recorded

III. overprint fault

(I) cause analysis of inaccurate overprint caused by improper adjustment of parts

1. The cone pin of the universal shaft or the coupling between the paper conveyor and the host is broken and worn, and the paper feeding is unstable due to the sudden speed and slowness of the paper feeding machine

2. The action of paper stop tongue, paper feeding suction nozzle and paper receiving roller is inconsistent. The relationship between the three should be: when the paper feeding suction nozzle just sucks the paper, the paper retaining tongue begins to tilt back, the paper feeding suction nozzle stops suction, and the paper receiving roller just presses the delivered paper on the paper receiving roller. If this is not the case, the paper is irregular before arrival, and the paper feeding speed is different

3. The pressure of the paper receiving roller is not adjusted well

if the pressure adjustment of the two paper receiving rollers is inconsistent, the paper will be skewed. If the lifting time is inconsistent, check whether the clearance of the adjusting screw is consistent

4. Improper adjustment of the paper pressing wheel on the paperboard, unstable paper, affecting overprint. It should be adjusted according to the paper quantity

5. The tightness of the thread belt is inconsistent, and the paper is skewed, which affects the paper feeding, resulting in inaccurate overprint. Tighten the cable strap again

6. Lifting the front gauge too early and too late. Generally, it will cause two phenomena: paper out of control and paper delivery teeth and front rule grabbing paper

7. The gap between the paper stop tongue on the front gauge and the paper table is inappropriate. The paper does not fall in place or falls too far. At this time, it should be adjusted according to the relevant provisions of the operation manual

8. The equal radius error of the front gauge cam is too large. If there is an error in the equal radius surface of the cam controlling the swing of the front gauge, the front gauge will move slightly when stabilizing the paper on the tooth table, resulting in inaccurate overprint

9. The paper delivery teeth close their teeth too early or too late at the dental table. The paper delivery teeth close their teeth too early at the tooth table, resulting in paper grabbing. If the teeth close too much biological hupernic acid, it can bring differentiated performance, and make the paper out of control

10. The braking force on both sides is inconsistent. Relying on the brake is the guarantee for the paper delivery teeth to hold the paper still on the tooth table. If the braking force is inconsistent, the paper delivery teeth shaft will be distorted, resulting in inaccurate overprint

11. The paper delivery teeth stay on the tooth table for too long or too short. If the paper delivery teeth stay on the tooth table for too long, it means that both sides are jacked up by the brake too much. On the contrary, if the stay time is too short, that is, both sides are jacked up by the brake too little, resulting in inaccurate overprint

12. The handover time between the paper delivery gripper and the embossing (paper transfer) drum gripper is too long or too short. The two teeth must be synchronized during the handover. Generally, if the handover time is too long, the more difficult it is to ensure the synchronization time of the cam

13. The paper delivery teeth bump against the front edge of the embossing cylinder. The edge knock is not allowed

14. The paper delivery gripper swings, and the cam roller jumps radially. The radial runout of the roller is generally the problem of the roller itself, but also the sum of the runout errors of the ball bearing

15. The swing arm pin shaft or sleeve is worn. If the pin shaft and sleeve are worn and loose and the overprint is not accurate, the pin shaft or sleeve shall be repaired and replaced in time

16. The spring force of side tension gauge is too large or too small. If the overprint is inaccurate due to the spring force, the compression spring shall be replaced according to the thickness of the paper

17. If the gap between the side pull gauge pressing board and the paper table is not appropriate, the paper sheet will be pulled too far or not in place

18. Radial runout of side pull gauge roller. The pressure on the paper varies, resulting in inaccurate overprint

19. The axial displacement of the drum is too large

20. The screw fastening the drum gear is loose, or the pin of the gland and hub is loose. This situation changes the relative working position of the drum body and drum gear, resulting in irregular overprint

21. The paper teeth slip. Reduce the paper holding force, resulting in inaccurate overprint

22. The height of the paper holding tooth pad is inconsistent. This situation makes the edge of the paper mouth uneven, which directly affects the overprint accuracy

the above are the main reasons for inaccurate overprint caused by improper adjustment of printing machine parts

(II) paper teeth and overprint inaccuracy

uneven paper teeth of the embossing cylinder can deform the paper and inevitably make the product overprint inaccuracy

in order to prevent uneven overprint of paper teeth, the following points should be achieved:

1. The adjustment of paper teeth should be carried out in the trial printing, and the gripping force should not be changed in the process of overprint of various colors

2. The gripping force of the gripping teeth of the embossing cylinder must be uniform

3. The supporting spring of the gripper shaft shall have good elasticity to prevent insufficient gripper force and inaccurate paper positioning

4. Tighten the tightening ring of the paper gripper. To prevent the paper teeth from moving axially, the paper teeth shaft or shaft sleeve with high manufacturing accuracy is used to keep the paper teeth in a stable state during the paper picking process, and the paper picking distance is always maintained at a constant value

(III) the handover relationship and overprint are not allowed

there are handover relationship problems in the whole transmission process of paper feeding, regular parts, paper delivery teeth and paper transfer roller. As mentioned above, the handover relationship refers to the handover position and handover time. The handover relationship is essentially to ensure the accurate transportation of paper, and the phenomenon of paper out of control is not allowed. The handover position refers to the handover of the paper at a certain point, and the handover time is the time for the handover machine to jointly complete the handover of the paper. The handover time can not be short or long. If the handover time is short, overprint must not be allowed. If the handover time is long, the mouth edge will be torn


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