Chain conveyor is a kind of material conveying equipment commonly used in industrial production. Although it is very common, it plays an important role in the normal operation of the whole production system. In the actual production, the main fault of the chain conveyor is the fault of the transmission chain. The transmission chain of the chain conveyor is the main part of the chain conveyor, which is a very important traction device. It consists of a connecting chain, a chain plate three parts connected to the chain link. Therefore, the selection of various components of the chain conveyor can transport the chain, which plays a key role in the normal operation of the chain conveyor. In view of this, this paper mainly analyzes the causes of the failure of the chain conveyor, in order to reduce the failure rate of the chain conveyor as far as possible, reduce its maintenance cost, improve the production efficiency.

1. Fault type

The fault types of the chain of the chain conveyor are as follows: the chain plate is damaged, the transmission chain is detached the groove of the chain conveyor, the transmission chain is detached the power sprocket, the connecting link is broken, the link is damaged.

2. Cause analysis

(1) The main damage of the chain plate is excessive wear bending deformation, occasionally cracks. The main reasons are as follows: ① the bottom plate of the groove of the chain plate machine is flat, the bending angle exceeds the design requirements; ② the bottom plate of the groove of the chain plate machine is well connected, partially deformed; the transmission chain is squeezed stuck, which can immediately bear large impact stress; ④ when the distance between adjacent chain plates exceeds the key requirements, the chain plate will be damaged by long-term overload operation.

(2) The main reasons for the drive chain coming out of the slot of chain plate machine are as follows: ① the floor of slot of chain plate conveyor is leveled according to the design requirements, but it is uneven excessively bent; ② the gap between the two is too large due to the serious wear of the chain plate slot of chain plate machine; ③ the length of the drive chain on both sides of the chain plate is different, the force is unbalanced; ③ the length of the drive chain on both sides of the chain plate is different, the force is unbalanced; ④ Chain plate deformation, bending too much, so that the chain link distance becomes smaller; ⑤ insufficient pre tightening force of the chain conveyor's conveying chain, will cause chain pile in the tail of the machine, so that the chain plate is easy to come out of the slot of the chain plate machine.

(3) The abnormal engagement of the power sprocket the transmission chain causes the transmission chain to fall on the power sprocket the phenomenon commonly known as "tooth skipping" occurs. The main reasons are: ① the power sprocket is seriously worn mixed with debris; ② the tension of the two chains is consistent; ③ the chain plate is seriously skewed the spacing is too large; ④ the head is installed correctly, the verticality requirements of the chain the head are consistent; ⑤ the excessive gap between the power sprocket the drive shaft will cause the power sprocket to tilt swing.

(4) The connection link is broken. All kinds of connecting chains used in chain conveyors in China are produced according to relevant standards. The breaking load is about 10 times of the tensile force of the chain. The safety factor is high. Theoretically speaking, chain accidents will occur, but the failure rate of the connecting chain in practical use is relatively large. The main reasons are as follows: ① under the condition of long-term pulsating load, far below the fracture tension fatigue damage, the fracture is generally connected at the arc linear transition of the chain link; ② the manufacturing quality does meet the standard, the material heat treatment level are close to each other; ③ the continuous contact between the transmission chain the slot, sprocket material of the chain plate machine produces friction, the arc is connected with the straight line. This is the most worn area. The bearing cross-sectional area decreases gradually, which leads to the decrease of strength. This is mainly caused by the outside of the straight part of the chain link the outside of the arc part by the material chain plate slot. Three parts of internal wear caused by internal wear; ④ The results show that the cross-sectional area tensile strength are reduced due to the corrosion, rusting, pit peeling of connecting rod; ⑤ the chain tension is broken when iron is added into the chain; ⑥ the transmission chain starts frequently under full load overload conditions, which makes the impact force of the transmission chain exceed the strength limit; the chain preload is insufficient too loose, which forms pile chain makes the chain plate break away the groove, resulting in chain phenomenon; When the tension is too large, the transmission chain of ambassador is too tight, which accelerates the wear of the chain. When the chain is stuck, there is no buffer room, the service life is shortened. The spacing between the chain plates exceeds twice of the required spacing. When it runs to the machine head, the chain without the chain plate will be tensioned due to the tension of the transmission chain, it cannot slide in the groove of the chain plate machine. The next chain plate is also tensioned with the chain, interferes with the discharge device of the machine head, causing chain blockage chain fracture; the tension of the two chains is inconsistent, so the load is concentrated on the tighter chain, thus exceeding the strength limit.

(5) The connecting rod is damaged. In practical use, the chain link is usually slightly larger than the conveyor chain, the wear is more serious. Therefore, the chain link has become the weak link of the whole conveyor chain. The damage is mainly caused by severe wear, rupture pulling. The main reasons are: ① long-term pulsating load, fatigue damage; ② connecting pin bolt loose, can be found in time, resulting in connecting rod stress. (3) for the vertical ring, the unilateral wear is more serious, if it is replaced in time, it is easy to break; (4) after the chain is stuck, it will produce a large dynamic load impact load, resulting in a large instantaneous speed of the conveyor chain. Fluctuation will make the conveyor chain unstable, thus accelerating the wear fracture of the chain link. ⑤ Poor manufacturing quality, low wear resistance toughness, low hardness fatigue cracks due to stress concentration, resulting in insufficient strength.