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前段时间参加了一次事故分析会,分析用模拟显示仪表控制盐浴炉进行高速钢淬火造成产品不合格的问题。究其原因,是使用人员没有正确掌握该仪表的使用方法的结果。模拟显示仪表是一种时间比例仪表,当炉温达到给定值的比例带前,继电器触头闭合,加热很快。炉温升到刚进入给定值的比例带时,继电器触头闭合(开) 的时间长于断开(关) 的时间,使加热缓慢。当炉温达到给定值时,继电器开与关的时间相等,即炉温的加热和不加热时间相等。若炉温超越给定值,但还在比例带中,继电器开启的时间比关闭的时间短,这样形成加热比不加热时间短,最终使炉温稳定在给定值附近的某一定值上。
Some time ago participated in an accident analysis will be analyzed with analog display instrument control salt bath furnace quenching caused by high-speed steel products failed. The reason is that the user did not correctly grasp the results of the use of the instrument. Analog display instrument is a time scale instrument, when the furnace temperature reaches a given value proportional band, the relay contacts closed, heated quickly. When the furnace temperature has risen to the proportional band just reached the given value, the relay contact is closed (on) longer than the off (off) time, causing the heating to be slow. When the furnace temperature reaches a given value, the relay turns on and off at the same time, that is, the furnace temperature is equal to the heating and unheating time. If the furnace temperature exceeds the given value, but still in the proportional band, the relay is turned on for a shorter period of time than the turn-off time. This results in heating being shorter than the non-heating time and finally stabilizing the furnace temperature at a given value.