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1.故障现象我们对2台某型挖掘机进行可靠性试验,当工作到约200h时,2台挖掘机斗杆缸均在同一部位出现了断裂,断裂部位位于缸筒底部支座的半径10mm过渡圆角位置,如图1所示。2.故障原因查找为了找出斗杆缸支座断裂原因,我们从斗杆缸支座结构、设计强度、机加工质量、化学成分、晶粒度等方面进行分析和查找,以求找出其断裂原因。(1)结构斗杆缸支座为45号钢锻造而成,屈服强度(σ_s)为355MPa,锻造后缓冷,钢材的晶粒
1. Symptom We conducted a reliability test on two excavators. When working to about 200h, the two excavator arm cylinders were broken at the same location. The fracture site was located at the radius of the bottom support of the cylinder 10mm Transition fillet position, as shown in Figure 1. 2. Fault Reason Finding In order to find out the cause of the broken arm cylinder bearing, we analyze and find it from the structure of arm cylinder support, design strength, machining quality, chemical composition, grain size and so on, in order to find out its Cause of fracture. (1) Structure Arm cylinder support forging made of 45 steel, yield strength (σ_s) of 355MPa, slow cooling forging, steel grain