Maintenance of Concrete batching plant

In the process of daily use, the maintenance of the mixing plant is extremely important. In recent years, the vigorous application of the concrete mixing plant has promoted the equipment maintenance to become more prominent, and the most important of these is the various components inside the mixing plant. The operating condition of the parts, the abnormal noise of the mixer generally means that the equipment is faulty. Therefore, it is necessary to train the operator's maintenance knowledge to be able to detect and solve hidden dangers as early as possible, so that daily production is guaranteed and the chain is not dropped. The following summarizes some experiences of daily maintenance:

1. Examine before use of Concrete batching plant

• Check the connection of power supply null line. All wire ends must be firmly connected, No loose & electric conductor leak out.
• Check the gearing, main connecting bolts for mixing device(including support bolts, arm and blade bolts, lining plate bolts, arm shaft connecting bolts, etc.). These shall not be loosened.
• Check whether there is any foreign matter in the mixer and must be removed to prevent jam in mixer.
• Check the lubrication parts, gear box, open gear, shaft-end seal should have enough lubricating oil.
• Check the water source. The water source must be clean and inclusion-free.
• After each inspection is ok, start the machine with no load and observe whether the direction of mixing shaft is consistent with the specified direction. If the direction is incorrect, the power supply connection position must be changed.
• Before use, check whether the thick oil pump has lubricating oil, and start thick oil pump to add oil to the shaft-end seal, until mixing arms & drum inner wall have oil came out .
• Check oil level height in crankcase of the air compressor. In winter use the No.13 compressor oil in the air compressor, and in summer use No.19 compressor oil. (Or refer to the air compressor instructions for refilling).
• Use after freezing season and long-term parking, please check the water and additive system to see whether there is oil leakage.
• Check the filter’s water situation in the airway system. If it is too large, open the manual valve to discharge; Check oil level in the oil mist, If it is too low, add HU-30 (GB253) anti-rust turbine oil or other equivalent lubricant, Unscrew blowdown valve at the bottom of gas tank to discharge waste water.
• The machine shall be free-load running 5 to 10 minutes to check the circulating situations of the oil, water, and gas lines, whether there is any obstruction, overflow, and discharging gate is flexible or not.
• Before the first normal working, mix about 1m3 mortar, in order to eliminate static clearance and reduce the abrasion of the mixer lining plates.
• Before normal operation, check if the lining plates and mixing blades are loose, and tighten them if loose.

2.After each work is finished, maintenance items should be done:

Clean the ash deposition inside and outside of the mixing tank wall, Clean the concrete residue the on discharging outlet, discharging gate and mixing shafts. Wash out these places with water. If necessary, put a small number of stones and water to mixing a few minutes, then discharge.

With water, clean the water, additive tank and its supply system.

During the freezing season, at the end of work, the water pump, additive pump, water tank, additive tank, additive pipeline shall be drained to prevent damage the pump and its piping, and start the addition pump, water pump to run 1 to 2 minutes.

Check maintenance items in every week

• Manual thick oil pump needs to be filled with lubricating grease or not.
• Each lubrication point must be lubricated.
• Note: Each lubrication point is located in the mixer discharge door hinges, each door hinge for storage hopper and weighing hopper, belt conveyor roller, pinch roller, drum, bearing, drive chain, screw conveyor, screw conveyor bearing, and the host gear Etc.
• Check the abrasion situation of mixing blades, scraper, mixing arms, etc. If necessary, adjust the clearance or replace. For the method of adjusting the gap, please see the section "Adjustment of the machine".
• Check vibrator coupling bolts have looseness or not .
• Check the oil quality in the crankcase of air compressor. Replace if necessary.
• Check the contactor in the electric appliance, if the Static and dynamic contact of intermediate relay is damaged and burned.

4.Check maintenance items at fixed period:

• Check the seal gap of discharge door. When the gap is too large, shoud adjust it. The seal gap is about 2 mm in generally.
• Mixing blades are continuously used in the case of adjustable time (including re-adjustment after 180° rotation). When fixed sunk screw came out from lining plate surface, the lining plates should be replaced.
• Check whether the reducer lubricant is deteriorated or less than the specified requirements. Fill or replace if necessary.
• Check the big gear abrasion situation.
• There must be no leakage for the water supply and additive system.
• Matched accessories, such as motors, gear motors, air cylinders, vibrators, air filters, etc., shall be repaired and maintained in accordance with the manufacturer's operating instruction.
• The concrete batching plant should be maintained one time every six months to check the reliability of all bolted parts. In generally the overhaul period should be carried out after about 4000 hours working.

Repair and maintenance for belt conveyor

In the inside of electric roller is equipped with No. 150 synthetic extreme pressure industrial gear oil. The amount of oil injection must be strictly in accordance with the value given on the nameplate. Too much or too little oil will affect the efficiency and normal operation of the electric roller. 200 to 300 hours after electric roller working, need to replace lubricating oil, and later the oil is changed every 500 hours. When changing the oil, the two oil plugs should be unscrewed at the same time, and the electric roller should be rotated to the lowest position until the oil inside roller is fully discharged.

The ZG-5 calcium grease is injected into the bearing chamber of the tail tensioning roller, and grease is applied to the lead screw. After each shift exchange, the residue on the bottom surface of adhesive tape, rollers and rollers surface shall be cleaned in time.

Note: The belt conveyor must be started under no load, otherwise there is a danger of damaging the electric roller!

Deal with the abnormal cases of  Concrete batching plant

• The screw conveyor doesn’t work: There may be foreign matter stuck or cement agglomeration. Open the bottom inspection hole, by spanner rotate the blade in the reverse direction to remove foreign matter.
• There are materials in the mixer, and sudden power failure. The screwdriver can be used to unscrew the manual button of solenoid valve, to open mixer’s discharging gate to release the material.
• Water and additive butterfly valves are damaged. You can manually open the butterfly valve to release water and additives.
• When feed water is slow, should open the deflation valve of pipeline pump to see if there is gas or need to clear the pipeline.

Concrete batching plant Safety notice:

• The master switch, rotary button and indicator light on the operation panel of control system should always check its correctness and reliability.
• The machine must be stopped and powered off during internal maintenance. During the inspection, it is forbidden to open the master switch to avoid personal injury or death. The operator should bring the main switch key by himself.
• When the host is running, it is forbidden to open the monitor cover to avoid accidents.
• When the machine is being overhauled, it must be repaired when various safety protection measures are effective.
• For any working part of the machine, if it is found that the work is abnormal, it shall be immediately shut down, and the trouble shall be carefully excluded in time. f.When the machine is completely shut down because of inspection, maintenance, and repair, the machine must be guaranteed not to be restarted.
• When cleaning the equipment before maintenance, the motor terminal box, limit switch, sensor, and solenoid valve box should be protected to avoid incoming water, potential safety hazards happen.
• If some safety devices need to be removed during inspection, these components must be reinstalled and fixed after inspection.
• When performing maintenance and lifting, ensure that the lifting equipment has enough power to ensure safety.
• It is forbidden to stack articles on platforms and ladders. When working in winter, there should be no snow and ice on handles, ladders and platforms.
• The electrical part must be overhauled regularly and any damage such as loosening or burning must be repaired immediately.
• At the time of machinery maintenance, maintenance of pneumatic and mechanical transmissions must have corresponding expertise, and air supply must be shut off during maintenance.
• When welding on the fuselage, electric leakage should be prevented under wet conditions.
• When the machine is running, it is forbidden to stay under the feeding belt.
• When the mechanical equipment is hoisted, the steel wire rope should have sufficient strength, and the angle between the steel wire rope and the horizontal direction is generally not less than 40°.
• The discharge door should be locked during the mixer’s overhaul to avoid accidents during maintenance or inspection discharging door.
• For the Bearing and Floating Seal, please use No. 1 calcium based grease.
• The mixer must not be stopped during the mixing process. If an accident occurs during the mixing process, the discharge gate should be opened to discharge the material to prevent the concrete from solidification.
• After the new mixer has been mixing 20-30 times, retighten the connecting bolts of fixed lining plate, mixing arm, mixing blade, and reduction gear box, and ensure that the gap cambered surface between the mixing blade and the tank lining plate is 6mm, and the end surface is 10mm.
• The weighing systems should be calibrated before each mass production.