The Joint Character Research Of High-speed Double-side Locking Toolholder-spindle Interface

Tool machine is a big assembly which is constituted of a lot of parts, and it hasmany connections. The spindle system that is the most important part is a determiningfactor for toolholder tip respond. But the connection of toolholder-spindle is one ofthe weakest parts in the machine tool. The related joint character is the key factor thatinfluence the performance of cutting stability. So the research of toolholder-spindleinterface is very important and has engineering value. Based on finite element contacttheory, the normal and tangential interactions between joint surfaces were consideredand the finite element model of BTF40toolholder-spindle was established in thispaper. The influence that drawbar force, centrifugal force and point load have on thestress and contact pressure of the handle body and handle sleeve, the contaction andseparation between taper shank and taper spindle hole, the contaction and separationbetween shank end face and spindle nose, the influence that disc spring stiffness haveon the joint connection properties were analysed. Through the research on virtualmaterial, it was found that hyperelastic material and fixed feature material could beused as virtual material applying in dynamic analysis of toolholder-spindle interface.At last it was identified that BTF40toolholder was better than BT during test resultsin practice.Based on the structure analysis of BTF toolholder system, the main work wasfocused on the joint character research of BTF toolholder-spindle. The importantcontents were listed as follow: The aim and significance of the work were discussedin this paper, and the research status of toolholder-spindle interface and the study ofcontact joint establishment were introduced; The features of BTF40toolholder andthe principle of double-side locking were introduced, and the finite element contacttheories based on toolholder-spindle interface were showed; FEA model of BTF40was established, and the effects of drawbar loads, spindle speeds, tip loads and springstiffness on the interface were analysed. And the results showed that12kN broachforce was selected in ensuring the contaction between the handle and the spindledouble; The highest speed could achieve20000rpm and the maximum radial forcetool tip could bear800N in the case that the contaction rate between toolholder andspindle was not less than60%.; Virtual material of mechanical structure interface wasbrought in. Several ways of defining interface virtual material which were applied in dynamic analysis were elaborated, and contact pair method were compared; Throughtest in machine tool, getting static stiffness and dynamic status stiffness of interfaceand cutting results. It verified that BTF40toolholder was better than BT40throughtest results.Comparing to other researches, the studies on BTF in this paper are located in theleading position. The research achievement enriches the high-speed machining tooldesign theory, which provides strong technical support for the design and manufactureof high-speed machining tools.