The Study On Indirect Squeeze Casting Of The Larger-diameter Retainer

With the development of modern industry and new casting technology,indirect squeeze-casting technology has been widely applied as an efficient,high quality and near finished-product methods of production.But the development of squeeze casting technology of the larger-diameter and ring castings is lagging behind.Especially in indirect squeeze casting process of the larger-diameter,ring and Al-Cu alloy castings,because of the wide crystallization-temperature range of Al-Cu alloy,the casting tend to generate hot-crack easilyAccording to this,in the experiment,via indirect squeeze-casting to form Al-Cu alloy main-shaft retainer of high speed machine tool.The effect of squeeze-casting method,die structure and gating system on the indirect squeeze casting was studied.Finally,by increasing the liquid metal filling capacity and Transmission effectively of the pressure, the larger-diameter retainer was indirect squeezed cast successfully.The results of study show that:(1) Through lower punching indirect squeeze-casting,spontaneous Filling of liquid metal can be avoided.(2) Through improved gating system,filling capacity of liquid metal can be improved, and pressure can be effectively transmitted.(3) Through improved miscellaneous system,the feeding capacity of miscellaneous system has been improved,so casting crack rate will be reduced.Because of the hot-crack tendency of Al-Cu alloy,the indirect squeeze casting hot-crack tendency test device was developed.Through actual measurement of variation rule of stress,strain and temperature of indirect squeezing-caste Al-Cu alloy during solidification,the mathematical relations among them were obtained.The results showed: when temperature was below 410℃,a rather great attacking stress was generated inside the Al-Cu alloy.According to it,judgment rules of mold-opened temperature in order to avoid hot-crack were presented.During processing of retainer of pillow,when dwell time reached 15s and temperature of casts were 425℃.which was a little higher than cracks-generating temperature,the generating rate of hot-crack was reduced to 7.2%.Finally,while the mold temperature is 200℃,the hold-pressure time is 15 second,the pouring temperature is 780℃,and the intensity of pressure is 200MPa,the retainer was produced using improved die successfully.