| Summary: | 碩士 === 國立中央大學 === 機械工程學系 === 107 === F
inite element method (FEM) is applied to de veloping a computer aided engineering
CAE) technique for simulating the weld ing process in assembly of a household air
conditioning rotary compressor. An FEM model in simulation of joining pump cylinder and
outer shell is established first for sequential three point welding, and the simulation results are
compared with experiments to verify the FEM modeling. The validated FEM modeling is then
applied to simulating simultaneous three point welding to predict temperature distribution,
residual st ress , and deformation in related parts. In particular , deformation of the vane slot and
the change of roundness of the pump after welding are investigated
FEM simulations and experiments show good agreement in temperature distribution in the
sequential th ree point welding of pump cylinder and outer shell. The constructed FEM model
is thus proved to be effective in analysis of three point welding. The three point welding
simulation technique is then applied to the simultaneous three point welding process . T he
calculation results show that during the simultaneous three point welding, the maximum von
Mises equivalent stress mainly exists outside the weld zone. When the welding process is
completed and the cooling process begins, the maximum von Mises equivalen t stress region
gradually moves to the heat affected zone ( HAZ )). The residual stress in the HAZ exceeds the
yield strength . Therefore, plastic deformation might take place in the core region of HAZ At
the same time, the simulation results of deformation s how that the roundness of the cylinder
has not changed, because the node displacement does not change much This is because the
temperature gradient is quite small in these regions which are far away from the welding zones
A lthough a slight change in the vane slot width is found after welding, it is still in the acceptable
range.
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