Eight common mechanical faults and troubleshooting

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Eight common mechanical faults and troubleshooting methods of gravure press

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core tip: it is dangerous to repair the running parts of printing equipment, and improper operation may lead to serious accidents, including life safety. Therefore, before troubleshooting, you must be familiar with the contents of the manual to ensure correct operation

[China Packaging News] it is dangerous to repair the running parts of printing equipment, and improper operation may lead to serious accidents, including life safety. Therefore, before troubleshooting, you must be familiar with the contents of the manual to ensure correct operation

the gravure machine has a complex structure and strong professionalism in maintenance. In addition to normal operation and maintenance, the adjustment and repair of the equipment should be entrusted to professional technicians. When a fault occurs, the technician should be able to make a simple analysis and take appropriate measures to ensure personal safety, product quality and protect enterprise property

one. The a/b reel connection failure rate of the unwinder is high

① it is necessary to check whether the a/b reel is synchronized and whether the transmission parts (synchronous belt) are effectively driven; ② Measure the actual coil diameter, compare it with the system self-test, and check whether the coil diameter is consistent; ③ Whether the connection position between the connecting arm and the winder is normal. Check whether the radio eye and reflection eye work normally and whether the detection position is correct; ④ Whether the action of the connecting cutter and the pressure roller is smooth and consistent, whether there is lead or lag, whether there is water vapor in the air pipe or whether the air pressure is too low, which affects the normal operation of the cylinder; ⑤ Whether the roll slips affects the electric eye detection (this problem will directly lead to large fluctuation of finishing tension and poor chromatic accuracy). When checking whether the material roll is installed, the operating thimble on the power side and the operating side does not fix the material roll; ⑥ The surface of the collector ring is oxidized or the carbon brush is seriously worn, and the electrical signal output and input are weak, which affects the power on action and feedback of components. It needs to be treated accordingly to make the component powered on and normal contact, and the maintenance needs to be powered off; ⑦ The adhesive tape has insufficient viscosity, so it needs to be replaced

II. Traction device failure

(1) steel roll traction is not synchronized

① check whether the rubber roll is pressed against the steel roll and whether the rubber layer of the rubber roll is aging; ② Whether the pressing reaches the specified air pressure, and whether there is air leakage or blockage in the air path; ③ Whether the speed of the steel roll is synchronized with the speed of the equipment, and whether the transmission parts (synchronous belt) effectively transmit power; ④ Whether the motor encoder works normally (asynchronous traction will directly affect the tension and chromatic accuracy)

(2) poor cooling effect

① whether the temperature of cooling water is maintained at 20~25 ℃, or whether cooling water is used at 5~15 ℃; ② Whether the water volume meets the requirements and there is sufficient cooling water circulation; ③ If there is scale in the cooling roll due to long-term use, which blocks the inside of the cooling roll, the high-pressure cleaning pump can be used to carry out high-pressure dissolution cleaning with acid solution to keep a good cooling water pipe unblocked

III. shaftless plate mounting mechanism failure

(1) gearbox heating

① it is necessary to check the lubricating oil in the gearbox in time. The lubricating oil can effectively maintain the lubrication of the transmission parts in the gearbox, and the cooling parts fail; ② When the gearbox heats up and the noise of the gearbox increases, there may be wear or damage to the transmission parts inside the gearbox, so it is necessary to stop the machine in time for inspection; ③ Check whether there is ink or solvent flowing into the gearbox from the cone ejector rod of the gearbox, resulting in bearing damage or other transmission parts damage

(2) the horizontal chromatic accuracy of the version axis is poor

① the cone plug structure on the power side is in the form of cylinder cone top, and whether the manual valve rotates when the cylinder exits (intake) state. Check whether the cone plug fits well with the cylinder and whether there is a slipping gap. Check whether there are scratches or heating at the joint between the cone plug and the cylinder; ② Whether the horizontal automatic permanent magnet low-speed motor of the shaft works normally and whether there is any abnormal phenomenon; ③ The action can be checked by manual chromaticity, and it can also be adjusted back to automatic after manual chromaticity adjustment to observe the change of chromaticity; ④ Reasons for the accuracy of printing plate or plate mounting

IV. imprinting mechanism failure

(1) poor ink transfer effect

① imprinting force. Check whether the actual stamping force is consistent with the pressure value of the regulating valve. The output pressure of the cylinder corresponding to the corresponding pressure gauge value can be calculated by the cylinder diameter. If it is inconsistent, it is necessary to check the pneumatic components, the air pressure of the main air source and whether there are mechanical resistance obstacles; ② Due to the poor quality of the embossing drum and the adhesion of impurities on the surface, the drum should be replaced

(2) chromatic accuracy problem

① the impression cylinder is a passive component, and in the pressed state, the cylinder and the printing plate should be in a synchronous state. If it is not synchronized, it is necessary to check whether the rolling bearing rotates flexibly and whether it is stuck; ② Check whether the embossing cylinder operates normally when starting printing; ③ Check whether the impression cylinder and the plate cylinder fit well

v. scraper mechanism problem

when the scraping effect becomes worse, you can check and eliminate the fault from the following aspects: ① confirm whether the screws, bolts, fixed handwheel, handle and scraper clamp of the scraper mechanism are locked and tightened; ② Check whether the screw, worm and worm gear pairs of the scraper lifting, back and forth, swinging and other frequently operated parts are worn and whether there is a gap; ③ Whether there are transmission, transmission parts stuck and inflexible. Whether the sliding bearings, transmission parts, rotating parts, etc. are adequately lubricated; ④ Whether the scraper works without ink. Ink acts as a lubricant between the scraper blade and the cylinder, but when the scraper blade is in rigid contact with the cylinder without ink, the scraper blade will have high friction and heat, which will also cause damage to the cylinder; ⑤ Whether the scraper swings smoothly. The scraper swing transmits the scraper swing power through the output shaft under the gearbox. This position is converted from circular motion to linear motion, and this part is easy to be ignored, so special attention should be paid to maintaining the flexibility of this part. The equipment has been used for a long time, and it is very easy to cause mechanical resistance due to aging of lubricating grease or dust accumulation

VI. ink tray lifting fault

ink tray lifting is achieved through the cooperation of worm gear pair and gear rack to achieve the purpose of lifting and self-locking. Usually, the failure of the lifting device is caused by insufficient lubrication, large lifting resistance, asynchronous lifting of the power side and the operation side, etc. the flexibility of the transmission parts that are prone to aging can be maintained by lubricating or cleaning the dust and ink on the transmission parts. When installing this part, both ends must be kept at the same horizontal height

VII. Inking roller failure

① inking roller rotation failure. If the motor is overheated, noisy, and the inking roller shakes (excluding the rubber quality problem of the inking roller and the jumping problem of the inking roller itself), check and repair the transmission parts if a large amount of plastic waste is buried underground

② upper ink roller pressing failure. The press/release state of the inking roller depends on the action of the cylinder. The working height of the inking roller can be met by adjusting the limit nut on the cylinder. If there is a problem with this part, it is necessary to check whether the air path is blocked, whether the air pressure meets the requirements, whether the limit is correct, and whether the moving parts are flexible

③ speed failure of inking roller. The transmission ratio in the inking roller mechanism is a fixed value. The speed of rotation is adjusted by potentiometer. The control source of potentiometer is frequency converter, which controls the motor frequency to meet the required rotation speed. You can understand the relevant electrical data and repair according to the electrical instructions

VIII. Longitudinal deviation correction mechanism failure

longitudinal deviation correction is driven by permanent magnet low-speed motor, and the signal is transmitted to the encoder of the chromatic system, which feeds back to each other to ensure the accuracy of overprint. When the longitudinal chromatic accuracy is poor (provided that it is not caused by the chromatic system) and the correction response is not flexible, you can check from the following aspects: ① check whether the chromatic encoder is faulty; ② Check whether the low-speed permanent magnet motor is faulty; ③ Check whether the film route is normal; ④ Check whether the worm gear pair works flexibly, and whether there is jamming, large resistance, etc. Whether the ball screws work flexibly and effectively, whether the ball screws on the left and right sides are in a horizontal state, and whether there is obvious obstruction or unsmooth action when the motor drives the lead screws on both ends to rise or fall at the same time. Pay attention to the maintenance and lubrication of worm gear pairs; ⑤ You can select the manual position of the chromaticity system, adjust it to the qualified chromaticity, and then select the automatic chromaticity, and watch the chromaticity deviation and longitudinal correction

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