Search Results

In the shop floor, cracking issue was noticed during assembly of valve seat and valve guide in the engine cylinder head, especially near the valve seating area. This paper reveals a non- linear finite element methodology to verify the structural integrity of a cylinder head during valve seat and valve guide assembly press-in operation under the maximum material condition, i.e., smallest hole size on cylinder head for valve seat and guide and largest diameter of valve seat and guide. Material and geometrical nonlinearities, and contact are included in this method to replicate the actual seat and guide press-in operation which is being carried out in shop floor. The press-in force required for each valve seat and valve guide assembly is extracted from simulation results to find out the tonnage capacity of pressing machine for cylinder head assembly line. Stress and plastic deformation due to assembly load are the criteria checked against the respective material yield.

In the assembly of axles and wheel hubs, a nut is frequently used to fasten them as one unit. In order for the nut to hold the assembly in its final position, crimping is a widely-used method which prevents nut from loosening. A reliable crimping process not only prevents movement of the nut during axle operation but should also minimize the possibility of cracking the rim. If the nut cracks during assembly, it can start to rust and deteriorate. The service life span of the axle assembly hence shortens as a result. The quality of crimping operation is determined by the component designs, the process parameters, and the crimping tool geometry. It would be time-consuming and costly to evaluate these factors empirically; let alone the requirement of prototypes in the early stage of a new program. A dynamic finite element methodology which adopts the Arbitrary Lagrangian-Eulerian formulation from ABAQUS explicit solver is developed to simulate the complete crimping process.

During the planetary gear assembly, staking is a widely-used method for affixing pinion shafts onto the position. A reliable staking process not only prevents the movement of shaft during transmission operation, but also minimizes the distortion of the assembly due to the staking process. The quality of staking operations is determined by the component designs, the process parameters, and the staking tool geometry. It would be extremely time-consuming and tedious to evaluate these factors empirically; not even mention the requirement of prototypes in the early stage of a new program. A Finite Element methodology is developed to simulate the complete staking process including shaft press in, staking, and after staking tool release. The critical process parameters, such as staking force, staking length, shaft and holes interference amount, etc., are then evaluated systematically.