Combination of Hydroforming and Joining

Abstract

Manufacturing of complex tubular workpieces often requires medium‐based forming processes. Because of the inaccessibility to the inside of the parts, joining of attached parts and part handling are difficult. Loss of accuracy during thermal joining is another disadvantage. A new method of spot‐joining by forming is a combination of hydroforming and clinching or hydroforming and self‐pierce riveting. In contrast to the standard method the clinching or self‐pierce riveting is done without die. A high pressure fluid undertakes the task of the die during joining. This die‐less procedure also extends the range of applications to areas which are not covered by standard techniques. By integrating joining into the hydroforming process, assembly processes can be shortened. In order to exploit velocity dependent material properties, for example increase in formability and decrease of spring back, self‐pierce riveting during the hydroforming process by means of impulse load has also been researched among other conventional quasi‐static force transmissions. Numeric simulations were used for the theoretical description of the procedure. One goal of the simulations is the characterisation of the most influential parameters on the process as a function of the material properties, tool kinematics/‐geometry and of the friction conditions. The simulation results permit not only the characterisation of the process, but also the theoretical predetermination of optimal joining parameters for various material and geometry combinations with fewer experiments.

Self-pierce riveting for sheet materials: State of the art

“…In contrast to the standard method, the riveting process is achieved without a solid die, instead high pressure fluid acts as the die during joining. The advantages of the Hydro-SelfPierce Riveting processes are the reduction of the number of processing steps and new design possibilities are feasible as joining in complex hydroformed units becomes possible also it allows SPR to be used in inaccessible places (Neugebauer et al, 2005). Han et al (2006b) reported the influence of sheet prestraining on the static and fatigue behaviour of self-piercing riveted aluminium alloy sheet.…”

“…Jin and Mallick (2002) found that ring coining improved the fatigue life of SPR joints in aluminium alloys and the degree of improvement may be dependent on the coining condition and the sheet thickness combination. A new method combining hydroforming and SPR was proposed by Neugebauer et al (2005). In contrast to the standard method, the riveting process is achieved without a solid die, instead high pressure fluid acts as the die during joining.…”

Clinching for sheet materials

“…Hydro-clinching is a new joining method involving a combination of hydro-forming and clinching that was proposed by Neugebauer et al [ 223,224 ]. In hydro-clinching, a high pressure fluid is used as the die and this substitution extends the range of applications for clinching to areas not covered by standard clinching methods.…”

Fatigue Behaviour of Fastening Joints of Sheet Materials and Finite Element Analysis

“…Jin and Mallick [36] found that ring coining improved the fatigue life of SPR joints in aluminum alloys and the degree of improvement may be dependent on the coining condition and the sheet thickness combination. A new method combining hydroforming and SPR was proposed by Neugebauer et al [37]. In contrast to the standard method, the riveting process was achieved without a solid die, instead high pressure fluid acted as the die during joining.…”