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Maintenance And Failure Analysis Of Rotary Packaging Machine

21 12 月, 2021

In the daily production process, due to inadequate maintenance and other emergencies, the rotary packaging machine will work abnormally. This article summarizes the daily maintenance content and troubleshooting methods of the packaging machine in the actual production process.

1. Electromechanical part

1.1 Feeding and transmission part

There is a vibrating screen installed on the top of the packaging machine, which plays the role of material transportation and screening of large particles of foreign matter in the cement, and prevents foreign matter from entering the packaging machine and causing the rotating parts of the packaging machine to jam. The daily maintenance of the vibrating screen is relatively simple. You only need to fill the bearing housing with about 100g of grease every week, and check the screen once a month. If there are cracks or leaks, you should replace the new screen in time; the corners of the screen are warped and loose. If you need to re-tighten the bead, if it cannot be tightened, you need to replace the new screen. If the dividing wheel feeder or cement nozzle feed impeller is stuck by foreign matter during the operation of the packaging machine, it is necessary to stop the machine immediately to check and replace the vibrating screen.
The structure of the transmission part of the packaging machine is that the electric motor drives the gear box through the triangular drive belt through the stepless transmission, and the large gear in the gear box drives the main shaft of the packaging machine to rotate. The rotating part is usually not prone to failure. You only need to use the production stop gap to check the lubrication of the V-belt and the gearbox. The inspection cycle can be flexibly adjusted according to the production situation. Generally, it is checked at least once a month.
It should be noted that the continuously variable transmission relies on adjusting the pressing force of the shift wheel to achieve speed change. The wear of the governor wheel and transmission belt after the use of time will cause the belt to slip or even fail to transmit. Therefore, the transmission should check the wear of the governor wheel and transmission belt and prepare spare parts. In terms of time arrangement, it is synchronized with the inspection of the reduction gearbox and the main shaft transmission belt.
Since the bottom bearing of the packaging machine needs to enter from the bottom ash hopper to be inspected, it is often ignored during routine maintenance. If the bottom bearing is damaged, it will affect the flexibility of the packaging machine’s rotation, and even cause the packaging machine’s spindle to jam and damage. Bearings must also be checked for lubrication and sealing at least twice a year. When the packaging machine is found to have high rotational resistance during operation or when it is not possible to push it by one person in an empty state, it is necessary to check whether the bearing is damaged as soon as possible.

1.2 Electrical control part

Affected by the operating environment, the electrical control part has a lot of dust, which can easily cause poor contact or signal interference. The main point of routine maintenance is to seal the electrical control box of the packaging. It is best to clean the dust in the electrical cabinet every shift. Check whether the signal of each sensor is accurate and whether the wiring terminals are in good contact.

1.3 Feeding impeller and weighing frame

When the feed impeller is abnormal, the ash output will be small or no ash will be output directly. The daily maintenance content is to check and replace the triangular drive belt. When it is found that the amount of ash is small or there is no ash but the nozzle is not blocked by foreign matter, the feed impeller needs to be checked. If the blade has a large amount of deformation, the welding seam at the root of the blade has cracked or the blade has fallen off, a new blade needs to be replaced. At the same time, pay attention to the lubrication of the bearing seat of the impeller box. Fill the lubricating cup on the bearing seat of the impeller with about 50g of lubricating oil every week.
The weighing frame should be protected from abnormal impacts. Do not hit with a small hammer. The weights and cement packs used in the calibration should be handled with care. Do not step on the weighing frame when repairing the upper parts of the packaging machine. Use ladders or other supports. When the deformation of the weighing frame has caused each hinge connecting rod to jam against each other, or the rotation is not flexible, it should be corrected or replaced in time. Adjust the height of the package at any time to ensure that the package does not tear due to the high height or the height is not enough to be stable. Material accumulation on the weighing frame should be avoided, and if there is, it should be cleaned in time to reduce the bag weight error.
The tightness of the clamping bolt of the discharge valve plate needs to be adjusted at any time at the nozzle position, so that the valve plate can move flexibly, and the gap between the valve plates can be reduced as much as possible to ensure sealing and reduce leakage at the valve plate. At the same time, adjust the opening of the valve plate in the thin flow state according to the weight of the package, the preset coarse/fine flow conversion preset weight, the rotation speed of the packaging machine and the system compressed air pressure. Generally, the valve plate of the discharge port should be fully opened in the coarse flow state, and the opening degree should be controlled between 1/4 and 1/3 in the thin flow state. The packaging machine’s rotation time should be controlled between 10-15s, and the packaging machine should make one revolution. Complete the process of inserting, filling and pushing the bag within to ensure production efficiency.

2. Pneumatic control system

2.1 Principles of Pneumatic Control System

The requirements of the rotary packaging machine for compressed air: the air pressure is 0.5 ~ 0.6MPa, not less than 0.4MPa, and the impurities such as moisture and oil in the compressed air are filtered as clean as possible.
Pneumatic control principle of rotary packaging machine
The pneumatic control system of the rotary packaging machine is divided into two parts. One way is the impeller box pneumatic assist flow, and the other way is the pneumatic control part.
1) Pneumatic flow assistance of the impeller box: compressed air passes through the shut-off valve and pressure reducing valve through the air pipe in the main shaft, and is distributed to the pneumatic control valve corresponding to each nozzle through the annular air pipe, and then enters an auxiliary air tank, through the throttle valve and the one-way The valve enters the impeller box. A dust plug is also installed in the impeller box to prevent cement dust from entering the compressed air pipeline. The control air source of the pneumatic control valve is connected with the solenoid valve that controls the action of the cylinder to realize pneumatic flow assistance during filling, so that the cement in the feeding impeller box is fluidized, the cement fluidity is increased, and the filling is easy to fill, and the filling is completed After that, the pneumatic assist flow stops.
2) Pneumatic control part: compressed air is distributed to the solenoid valve seat corresponding to each nozzle through the air pipe in the main shaft through the shut-off valve, filter and pressure reducing valve. After the valve operates according to the predetermined program, it controls the three-position cylinder (Y1 and Y2), the bag pressing cylinder (Y3) and the bag pushing cylinder (Y4) respectively to complete a series of actions of bag pressing, filling, coarse and fine flow conversion, closing and bag pushing , To complete the production of bagged cement. When Y2 acts, the pneumatic valve acts, and the flow-aid air circuit is connected.

2.2 Failure cause analysis and treatment methods

1) Cylinder damage: The failure is straightforward. If the air path is unobstructed, the valves operate normally but the cylinder does not operate, it can be concluded that the cylinder is damaged, and only the damaged cylinder needs to be replaced.
2) Damage or blockage of the pneumatic control components will cause the air path to be unsmooth, and the cylinders may still operate, but the timeliness and accuracy of the actions will be affected. When the valve completes the predetermined action, the action is slow and cannot be fully in place. The feed valve cannot be converted from coarse flow to thin flow in time when the feed valve is changed. The valve cannot be completely closed when the valve needs to be closed. Carefully check each pneumatic control component item by item to eliminate the problem. When our company found that the bag weight fluctuates in the early stage, it simply recalibrated the scale. As a result, the bag weight fluctuation was not resolved. Instead, the frequency of calibration continued to increase. Later, after careful analysis of the failure phenomenon and the principle of the packaging machine, the control gas The road system was thoroughly inspected and dealt with to solve the problem.

2.3 Daily maintenance

1) Dust plug and one-way valve: If the surface of the dust plug in the feed impeller box is blocked by cement, the compressed air cannot enter the impeller box to aid flow, and there will be poor discharge and unstable discharge. If the dust plug or the one-way valve falls off and is damaged, the cement dust enters the compressed air pipeline of the packaging machine, which will block the entire pneumatic system components and damage it. Therefore, when the cement flow is small, there is no foreign matter blockage at the nozzle, and the compressed air pressure and throttle valve are normal, check and replace the dust plug in the impeller box to ensure unobstructed air flow. If dust is found in the compressed air pipeline and the solenoid valve is blocked, the dust plug is damaged and needs to be replaced.
2) Throttle valve: The throttle valve plays the role of adjusting the flow-assisted air volume. If it is found that the air flow cannot be adjusted or is blocked, it needs to be replaced to ensure that the flow-assisted air volume can be adjusted at any time according to the needs.
3) Pneumatic control valve: The spring and piston in the valve are easily blocked and damaged, which can cause the pneumatic flow assistance to be unable to connect, and the cement in the impeller box cannot be fluidized. The nozzle discharge is small or does not discharge. When it is found that the discharge volume is small and the nozzle is not blocked by foreign matter, the quick connector on the detachable air pipe can check whether the compressed air pressure and flow are normal. If the air flow is small, the pneumatic control valve should be disassembled to clean the valve core, or replaced directly.
4) Solenoid valve: Affected by moisture in the compressed air, the spool of the solenoid valve will be rusted and jammed after a period of use, and cannot operate normally or does not move properly, resulting in slow or no movement of the cylinder. When Y1 and Y2 fail, the three-position cylinder cannot operate normally or is slow, and the coarse and fine flow valves cannot be opened or closed in time, which will cause a large error in the weight of the cement bag. When Y3 fails, it may happen that the bag pressing head cannot be pressed or loosened in time, causing the packaging bag to fall when the first filling is started, or cannot fall and tear when the bag is pushed. When Y4 fails, the packaging machine may not be able to push the bag or the speed of the bag push is too slow. The cement bag cannot fall into the middle of the conveyor belt, or even directly under the conveyor, which is easy to block the bag and squeeze the bag to rupture. Therefore, after the packaging machine is shut down, all solenoid valves need to be checked, and the solenoid valves that are not functioning properly are removed to clean the spool, or directly replaced. If there is no daily downtime, the solenoid valve should be thoroughly inspected and cleaned at least once a week to ensure that the packaging machine is in good working condition.
5) Solenoid valve seat silencer: There are 2 silencers on the upper end of the solenoid valve base, which are the solenoid valve exhaust ports. If the muffler is blocked, it will not be able to exhaust normally, which will cause the cylinder controlled by the solenoid valve to act slowly and not in place, which will also seriously affect the production and quality of the packaging machine. Therefore, the exhaust muffler must be inspected at the same time as the solenoid valve is inspected weekly to ensure that the exhaust is unblocked.
6) The pneumatic control system is a whole closely related to each component. The maintenance of the pneumatic control system of the packaging machine is a systematic maintenance work, and it is not possible to check and maintain only a certain component. According to the actual situation, our company arranges regular inspections of about 4 hours a week to conduct a comprehensive inspection and maintenance of the pneumatic control part of the packaging machine, and at the same time carry out the lubrication of the mechanical transmission part, the fastening of the connection and the sanitary cleaning.

3. Concluding remarks

The composition of the rotary packaging machine is relatively complex, including electrical, transmission, mechanical and pneumatic technologies, so its principles must be fully grasped, and sudden failures can be timely and accurately judged and analyzed. At the same time, formulate a reasonable maintenance system and do a good job in daily maintenance. By strengthening daily maintenance, our company has made the packaging machine run smoothly and the weight of the factory bagged cement is stable.

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