Maintenance of the mixing machine is an effective means to restore its technical performance and prolong its service life. Improper maintenance will reduce reliability, reduce service life, and even cause mechanical accidents. This article discusses in detail the maintenance methods and precautions of the mixing machine.
Requirements for the use of concrete raw materials
The concrete mixing plant adopts double horizontal shaft forced mixing host, which can mix all kinds of hard, fluid, plastic lightweight aggregate concrete and mortar. The applicable aggregate particle size is not larger than 150mm, of which the aggregate with particle size 120~150mm should not exceed 10% of the total capacity.
Washing and cleaning of mixing machine
Cleaning frequency and method
The mixing machine should be cleaned at least once in one working cycle. At the end of daily production, the mixing host should be fully cleaned. During the cleaning process, put water and a little stone into the mixing host and mix it for 5~10 minutes, and then remove all the materials in the machine without water and material accumulation.
Comprehensive cleaning after production
After stopping the machine, then rinse the pipeline and remove the dust and adhering concrete inside and outside the mixing tank. Generally speaking, the mixing host adds about 180~210kg of water, or you can bring your own high-pressure water gun for cleaning.
Precautions for flushing the material door of the mixing machine
When rinsing the material door of the mixing machine, it should be avoided that the accumulated material under the upper rinsing forms the phenomenon that the material door is stuck. During the mixing process, if the concrete transportation truck is not in place for a long time (more than 20~30 minutes, especially in summer), water should be added to the mixer for simple cleaning.
Safety measures for manual cleaning
During normal production, the solidification of concrete in the mixing cylinder and on the mixing shaft should be checked regularly, and if there is any solidification, it should be shoveled out manually in time according to the requirements. Before cleaning the mixing cylinder manually, cut off the power supply, air circuit, release the residual gas and lock the control room; when cleaning the mixing cylinder manually, it is strictly prohibited to strike the mixing shaft, mixing arm and mixing blade violently.
Reducer maintenance
Oil use
Recommended oil for reducer of mixing machine: gear oil for reducer, Meihu 630#. Reducer first run or replacement parts should be changed after 200 hours of work, the second should be changed after 500 hours of work, and then according to the use of the situation and the quality of lubricating oil can be changed every 2500 hours of operation; different types of lubricating oil can not be mixed; the oil level should be checked every month, and should be replenished if the oil is insufficient.
Inspection and precautions
Before starting the machine, the oil level should be checked whether it is reasonable and whether the ventilation holes are blocked by dirt: if the ventilation holes are blocked, the sealing ring will be easily extruded due to the increased pressure in the inner cavity when the reducer is working, resulting in the leakage of the reducer.
Oil change cycle and oil seal replacement
Reducer should be tested after the first few hours of operation shell temperature (should not exceed 70 ~ 75 ℃) and reducer connecting bolts, coupling connecting bolts are tightened well; mixer should be used in the first week of daily testing, and then monthly testing. When repairing the reducer or the oil seal has been extruded, the oil seal should be replaced. Reducer at least once a year to replace the oil seal. If the reducer is idle for a long time, it should be filled with lubricating oil first, and when it is used again, the excess oil should be discharged to maintain the correct oil level.
Maintenance of unloading mechanism
Use of hydraulic oil
It is best to use anti-wear hydraulic oil, and should be determined according to the use of oil change cycle, generally recommended every 6 months to replace the hydraulic oil, and clean the oil tank, oil suction filter, pipeline. Cleaning of the hydraulic system must be clean environment, no dust and other pollution, otherwise it is easy to cause hydraulic system failure, such as solenoid valves, hydraulic cylinders damage.
Tank cleaning and system pressure
The system pressure at start-up shall not exceed 12MPa, if the pressure over the unloading door seal wear more than 1/2 high, the relief valve should be adjusted. Then it needs to be replaced. When using the manual pump to open the door, you can not use too much force to avoid damaging the manual pump. After the manual operation, you must also turn the handle of the manual solenoid reversing valve to the neutral position, otherwise the discharge door cannot be switched on and off under the automatic production state.
Sealing and lubrication of mixing machine
Lubricant selection and filling method
The shaft end of the mixing host adopts centralized lubricating oil circuit and air pressure protection device double sealing to realize lubrication, sealing and cooling for the supporting seat and mixing shaft end parts. The lubricating grease generally adopts 00# lithium grease in winter (temperature ≤10℃) and 01# lithium grease in summer (temperature >10℃). Grease must be injected into the tank through the inlet filter, and it is strictly prohibited to open the gas-permeable cover of the tank for refueling. If the tank is completely empty, after filling fresh grease, it must be left for 10~15 minutes before starting the pump.
Grease inspection and replenishment
When the mixing machine is working, it should check whether the grease reaches the shaft end at least twice a day. In the 4 shaft ends are equipped with 1 spare grease nozzle can be used to press the ball core of the grease nozzle with the top of the fingernail, if there is no grease coming out, it means that the work is not normal and needs to be checked and cleaned up. If the automatic lubrication system fails, it is necessary to supply oil manually, every 2 hours to supply oil, until the inside of the cylinder 4 shaft ends have grease overflow can be.
Adjustment of air pressure protection device
Adjustment steps of air pressure protection device: open the ball valve, and at the same time ensure that the air pressure solenoid valve is normally closed, rotate the regulator handle, adjust the air pressure to 0.1-0.15 MPa; solenoid valve is in working condition, should ensure that there is compressed air at the end of the shafts, and the air pressure is 20-50kPa is normal. When feeding into the mixer, the air pressure solenoid valve of the mixer control system will be opened; when the mixer is unloading, the air pressure solenoid valve will be closed. The surface temperature of the air pressure solenoid valve can reach 120℃ under the continuous working condition, so don’t touch it to avoid burns.
Conclusion
The maintenance of the mixing machine can not only effectively restore its technical performance, but also prolong its service life and prevent the occurrence of mechanical accidents. By carrying out maintenance in strict accordance with the above methods, it can ensure the normal operation of the mixing mainframe, improve the production efficiency and guarantee the construction quality.
