Inquiry into Failure Reasons of Melt Conveying Gear Pump
A complete melt transmission gear pump is mainly composed of four parts: motor, reducer, universal coupling and pump head. Haike is a professional manufacturer of melt pumps in China. Melt pumps include plastic sheet melt pumps, high temperature extruder melt pumps, high viscosity melt pumps, etc.
There are two main reasons for gear teeth breaking: the first is that the gear will break when it is suddenly overloaded, and no foreign body is found to enter after disintegration, and from the point of view of the broken part at the root of the gear, the possibility of breaking the gear suddenly under overload can be ruled out. The second reason is that the gear tooth is like a cantilever beam, the bending stress at the root of the tooth is the largest after loading, the size of the transition part at the root of the tooth has changed greatly, and the machining tool marks left along the width direction of the tooth have caused a certain degree of stress concentration. Therefore, when the gear is repeatedly loaded, fatigue cracks will occur at the root of the tooth and gradually expand. This is the direct reason for the breakage of the driven gear of the melt pumping W-wheel pump.
Fracture of gear shaft: Fracture occurs in the transition part between gear teeth and shaft. It is obvious that there is a greater stress concentration in this part. When the follower gear shaft is subjected to repeated bending stress, fatigue cracks will occur in this part, and gradually expand, leading to fracture of gear shaft. The reason for the breakage of driven gear and the failure of driven shaft is that the lubrication condition of sliding bearing becomes worse and gradually bites to death, resulting in alternating bending stress and twisting stress, which results in the fatigue fracture of the root of driven gear and the transition part between the shaft and the gear (i.e., the place where stress concentration occurs) under alternating bending stress and twisting stress.