Fatigue strength of inner knurled interference fit joined by forming and cutting methods

Lukas Suchy,B Awiszus,A Hasse,T Gerstmann,E Leidich

doi:10.3221/igf-esis.49.41

Lukas Suchy, B Awiszus + Show 3 more

Open Access

https://doi.org/10.3221/igf-esis.49.41

Copy DOI

Abstract

The joining of machine parts by plastic forming is a common method for transmitting forces and torque. In drive trains, the ‘knurled interference fit’ has a high transmission capacity through the combination of frictional connection and form fit. In the present study, the shaft specimen made of C45 steel material is joined with an inner knurled hub made of 16MnCr5 case hardened steel. The influence of the joining process parameters on the torsional fatigue strength of the shaft-hub connection is investigated by means of experimental studies. The most important parameter is the chamfer angle of the knurled hub, which determines the rate of strain hardening in the material and differs between the cutting and forming joining processes. This study shows that knurled interference fit connections joined by forming achieve a higher fatigue strength and a higher maximum static torque than connections joined by cutting.

Highlights

A knurled interference fit (KIF) is a component connection that can be used in various applications, such as torque transmission connections
This study shows that knurled interference fit connections, joined by forming, achieve a higher fatigue strength and a higher maximum static torque than connections joined by cutting
Compared to forming joining, for cutting inversed knurled interference fit (I-KIF) a higher slope can be determined at the beginning of the joining process (Figure 3a)

Summary

INTRODUCTION

A knurled interference fit (KIF) is a component connection that can be used in various applications, such as torque transmission connections. Further calculations of the static load capacity in studies reviewed by the authors are predicated on the shear failure or equivalent stress of the counter profile [3,4,5,6]. Some of these studies regard the strain hardening in relation to the shaft chamfer angle φ, which divides the joining process into cutting and forming joining [7]. The high-cycle fatigue life of an inversed knurled interference fit (I-KIF) is investigated by means of experimental torque fatigue tests. Regarding the forming and cutting joining process, existing studies on fatigue strength of pre-strained specimen [11, 12] suggest a higher fatigue strength of the investigated materials

EXPERIMENTAL SETUP

Results

CONCLUSION