The maintenance of concrete mixing plant is an effective means to restore its technical performance and prolong its service life. Improper maintenance will reduce the reliability, service life and even cause mechanical accidents.
1. Requirements of concrete raw materials
The concrete mixing plant adopts double horizontal shaft forced mixer, which can mix various kinds of hard, fluid, plastic and light aggregate concrete and mortar. The applicable aggregate particle size should not be larger than 150 mm, of which the aggregate particle size of 120-150 mm should not exceed 10% of the total capacity.
2. Cleaning and cleaning of the mixing machine
Concrete mixing plant mainframe should be cleaned at least once in a working cycle. After concrete mixing plant the daily production, the main mixing machine should be cleaned comprehensively by putting water and a little stone into the main mixing machine for 5-10 min, and removing all the materials inside the machine after cleaning, without accumulating water and materials; flushing the pipes after stopping, and removing the dust and adhering concrete inside and outside the mixing tank. In general, the mixing machine should be filled with water about 180-210kg, other models can be increased or decreased accordingly, and you can also provide your own high-pressure water gun for cleaning.
When flushing the material door of the mixing machine, avoid the phenomenon that the material accumulated under the upper flushing forms a foreign body stuck in the material door. During the mixing process, if the concrete truck is not in place for a long time (more than 20-30 min, especially in summer), water should be added to the mixer for simple cleaning.
During the normal production period, the concrete solidification in the mixing cylinder and on the mixing shaft should be checked regularly, and if there is any solidification, it should be removed manually as required. Before cleaning the mixing cylinder manually, concrete mixing plant power supply and air circuit must be cut off, the residual air must be released and the control room must be locked; when cleaning the mixing cylinder manually, it is strictly prohibited to hit the mixing shaft, mixing arm and mixing blade violently.
3. Maintenance of reducer
Recommended oil for the reducer of the main mixing machine: SICOMA gear oil for gearbox, Mobil 630#. The oil should be changed after the first operation or replacement of parts for 200 h. The oil should be changed after the second operation for 500 h. Later, the oil can be changed once every 2,500 h according to the usage and the quality of lubricant; different types of lubricants cannot be mixed; the oil level should be checked every month and should be replenished in time if the oil level is insufficient.
Before concrete mixing plant starting the machine, check whether the oil level is reasonable and whether the vent hole is blocked by dirt; if the vent hole is blocked, the seal ring will be easily extruded when the reducer is working due to the increase of pressure in the inner cavity, resulting in leakage of the reducer.
The reducer should be tested after the first few hours of operation shell temperature (should not exceed 70 ~ 75 ℃) and reducer connection bolts, coupling connection bolts are well tightened; mixer should be tested daily for the first week of use, and then tested monthly.
When the reducer is repaired or the oil seal is extruded, the oil seal should be replaced. The oil seal of the reducer should be replaced at least once a year. 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 drained to maintain the correct oil level height.
4. Maintenance of unloading mechanism
It is better to use LHM46 anti-wear hydraulic oil, and should determine the oil change cycle according to the use, generally recommended to replace the hydraulic oil once every 6 months, and clean the oil tank, oil suction filter and pipeline once. The environment must be clean when cleaning the hydraulic system, there must be no dust and other pollution, otherwise it is easy to cause hydraulic system failure, such as solenoid valve, hydraulic cylinder damage, etc.
The system pressure at start-up must not exceed 12 MPa, if the pressure is too high, the relief valve should be adjusted. Discharge door seal wear more than 1/2 will need to be replaced. Do not use excessive force when opening the door with manual pump, so as not to damage the manual pump. After manual operation, the handle of the manual solenoid valve must be turned to the middle position, otherwise the unloading door cannot be opened and closed in the automatic production state.
5. Seal and lubrication of the main mixing machine
The shaft end of the main mixing machine adopts centralized lubricating oil road and air pressure protection device to achieve lubrication, sealing and cooling for the support seat and shaft end of mixing shaft.
The grease generally adopts 00# lithium grease in winter (temperature ≤10℃) and 01# lithium grease in summer (temperature ≥10℃). Grease filling to the tank must be injected through the inlet filter, and it is strictly forbidden to open the tank air cover for refueling. If the oil tank is completely empty, it must be left for 10-15 min after filling with fresh grease before starting the oil pump.
When the main mixing machine is working, it should check at least 2 times a day whether the grease reaches the shaft end. In the four shaft ends are equipped with a spare oil nozzle can be used to nail the top of the grease nozzle ball core, if no grease emerges, indicating that the work is not normal, need to check and clean up. If the automatic lubrication system fails, you need to supply oil manually, once every 2 hours, until there is grease overflowing from the 4 shaft ends inside the cylinder block.
Air pressure protection device. Its adjustment steps: open the ball valve, while ensuring 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 each shaft end, air pressure in 20 ~ 50 kPa that is normal.
When feeding into the mixer, the air pressure solenoid valve of the mixer control system is opened; the air pressure solenoid valve is closed when the mixer is unloaded. The surface temperature of the air pressure solenoid valve can reach 120℃ under continuous working condition, so be sure not to touch it to avoid burns.