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一、问题的提出 1970年下半年,西安柴油机厂自行设计的295型柴油机成批投产后,于1971年发现有10％左右的曲轴在使用中断裂,其主要原因是结构设计不合理。当时为了减轻重量、缩小体积、便于手摇起动、简化结构,曲轴的结构采取了两支承。这种结构设计被认为是文化大革命中的新生事物。但实际上两支承曲轴受力比通常的两缸三支承大得多,新产品设计后也未经小批试制就大批投产,结果使很多曲轴在使用中断裂。要解决这个问题,曾提出三个方案: 1、修改设计。但这方案影响太大,不仅产品结构要修改,工艺、工装都得修改,等于重新设计,同时还认为这是否定新生事物,所以这方案被否定。 2、将球墨铸铁曲轴改用45号钢锻造。可是这一方案又不符合以铸代锻的方针,因为曲轴断裂不是材料问题。另外,该厂没有那么大的锻造设备,曲轴毛坯锻造还得外
First, the issue raised In the second half of 1970, Xi’an Diesel Engine Factory designed 295 type diesel engine put into mass production, in 1971 found that about 10% of the crankshaft in use fracture, the main reason is the structural design is not reasonable. At that time, in order to reduce weight, reduce size, easy to start hand crank, simplify the structure, the structure of the crankshaft took two bearings. This structural design is considered a new birth in the Cultural Revolution. But in fact the two bearing crankshaft stress than the usual two three cylinder support is much larger, after the new product design without mass production of large quantities of trial production, resulting in a lot of crankshaft fracture in use. To solve this problem, three proposals have been made: 1. Modify the design. However, the impact of this program is too great. Not only the product structure needs to be modified, but the process and tooling have to be modified to equal the redesign. At the same time, it is also considered as a negation of new things. Therefore, the proposal is rejected. 2, the ductile iron crankshaft switch to 45 steel forging. However, this solution again does not meet the casting forging guideline, because the crankshaft fracture is not a material problem. In addition, the plant is not so big forging equipment, crankshaft rough forging have to