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前几年,我们在开发JW250和JS500混凝土搅拌机时,在完成样机试制和性能试验后,按常规只做300～50Oh的模拟试验或使用考核,整机和关键零部件均未进行较长时间的可靠性试验,致使存在的许多问题未能充分暴露和解决,给批量生产带来很大隐患。 以河南洛阳市某建筑工地使用的JW250搅拌机为例。该机在实际运行1200h后,总故障频数N=230次,若以工作时间组中值t_i为横坐标,经验故障密度f~*(t)为纵坐标,可画出图1所示
In the past few years, when we developed the JW250 and JS500 concrete mixers, after completing prototype trials and performance tests, only 300 to 50Oh of simulation tests or use assessments were routinely performed. The entire machine and key components did not take a long time. Reliability tests have caused many problems that have not been fully exposed and resolved, and have brought great potential for mass production. Take the JW250 mixer used at a construction site in Luoyang City, Henan Province as an example. After the actual operation of the aircraft 1200h, the total failure frequency N = 230 times, if the working time group median t_i for the abscissa, the empirical fault density f ~ * (t) for the ordinate, you can draw as shown in Figure 1