In one of the customer cases , a central chain bucket elevator is used to convey materials mainly with water slag and fly ash. After being put into use, due to the large water content of the slag, slag is formed in the bucket, and the thickness of the slag is up to 300 mm, and the bucket is worn. After the slag was cleaned up, there occurred three times chain breaking in the subsequent use of the machine. Through investigation,central chain bucket elevator was found that the bucket was not properly installed, and the chain design also had drawbacks.

1.The chain bucket elevator Reasons and solutions for chain breaking
1.1The installation problems of bucket
The mounting hole of the bucket is not accurate enough. On-site inspection found that the bucket hole size is 1~2mm larger than the requirement, so the installation becomes easy, but the gap between the bolt and the bucket hole is very fast due to the not use of the expansion bolt. In addition, the fixing device is improperly installed, and the nut of the bucket fixing bolt is welded. This kind of connection without elastic force will cause serious wear in the large load transmission and vibration. The above factors causes the fixing device of the chain to loosen, and also causes the large gap between the outer connecting piece and the intermediate chain.
1.2The central chain bucket elevator chain design has low safety factor
The breakage of the pin in the middle chain roll is the direct cause of the chain breaking. According to the safety factor calculation standard provided by the field tester, the conclusion is that the safety factor is less than 10. The solution is to replace the pin with high breaking force: the breaking force is increased from 1500kN to 2000kN, and the safety factor is increased from 7.15 to 9.6.
1.3The central chain bucket elevator Other aspects of modification
1)Installation accuracy
Re-align the level and center of the head and tail wheel spindles, strictly control the level within 0.04mm/m according to the industry installation standard, and limit the center deviation within 2mm to reduce the shear force that the swing of chain to the pin shaft. Shear force, this repeated shearing action exceeds the strength yield limit of the pin, causing the pin to break.
2) On-site inspection found that the head wheel rim had been lacked 6mm (from 30mm to 24mm), which increases the wear on the chain, replaces the rim according to technical requirements; replaces the discharge port plate to reduce the return operating load.