Design And Development Of Collapsible Spacer Used In Drive Axle Pinion Gear Assembly

Collapsible spacer is also called crush sleeve,crush spacer or compressible sleeve.It is axisymmetric part made of mild steet,with a corrugated area in the middle and different diameter on each side.When compressed,its axial force rise to a specific extent and then remains approximately constant.It is mostly used in pinion gear assembly of a drive axle,making stepless adjustment of tepered roller bearing's preload possible.By adopting collapsible spacers,repetitively selecting suitable shim thickness for the pinion gear assemblies can be eliminated,assembly efficiency can be largely improved.In this thesis,collapsible spacer's working principles and design objectives are deeply analyzed firstly.Then tensile tests of the mild steer which collapsible spacers are made of are conducted to acquire the true stress-strain curve of the material.Following that,a new type of shape of collapsible spacer is introduced.Based on the new type of shape,collapsible spacer's behavior during compression is studied using nonlinear finite element method.Then,the relationship between collapsible spacer's performance and its dimensions is studied using design of experiment and response surface fitting.Finally,Multi-objective genetic algorithms are adopted to optimize the design result.An integral process of designing collapsible spacer is summarized.Meanwhile,sample pieces are machined for two type of drive axles.Compression experiments,trial assembly,drive axles' bench tests and whole vehicles' road tests are carried out to make sure collapsible spacers' reliability.The significances of this thesis are: the designing process given by this thesis can help shorten design cycle of collapsible spacers while ensure their performance,it also serves as a reference when designing similar parts.