This paper is devoted to investigating: 1) the distribution of the residual wall thickness in gas-assisted molded tubes with contractional and expansional transitions; 2) the mechanism of this distribution of the wall thickness; 3) the effects of adding fillets to transitions on improvement of the uniformity of the residual wall thickness; and 4) the distribution of the residual wall thickness in curved sections and its relation to processing conditions.
Expansional Transitions Filled With Melt Before Gas Injection
The residual wall distribution at expansional transitions depends on whether that specific transition section is filled with melt at the instant of gas injection.
Expansional Transitions Not Filled With Melt Before Gas Injection
Figure 5 shows the residual wall thickness at expansional transitions that were not filled with melt until gas-assisted filling occurred.
After gas is injected in, the gas drives melt through the empty expansional transition to fill the tube cavity.
Figure 8 shows the residual wall thickness at expansional transitions with 45[degrees] fillets filled with melt before gas injection.
The distributions of the residual wall thickness near an expansional transition depended on the melt filling conditions at that specific transition.