标题: 【求助】请斑竹指点！ [打印本页] 作者: laogui2003 时间: 2003-6-13 13:15 标题: 【求助】请斑竹指点！ ::?::?::?Bulk temperature 到底是甚末意思？Bulk temperature 为甚末会在出现Overpacking的地方降低？作者: SCH 时间: 2003-6-13 13:54
About the bulk temperature result
About this result
The temperature of polymer melt changes not only with time and location, but also with thickness during the entire injection molding cycle. It is difficult to illustrate all these changes in a single display. Instead, bulk temperature is used to indicate the weighted average temperature across the thickness. Bulk temperature has more physical significance than a simple average temperature as the polymer melt flows. Bulk temperature represents the energy that is transported through a particular location.
Using the Bulk temperature result
Bulk temperature is a velocity-weighted average temperature when the polymer is flowing and a simple average temperature when the flow stops. For each element, a plot of bulk temp versus time shows that the switch-over from bulk temperature to average temperature gives a smooth curve. Uniform bulk temperature distribution during filling is desirable for mold design.
Bulk temperature displays are an alternate way to examine the flow distribution. Areas with continuous flow (heat convection) typically have a higher bulk temperature. The bulk temperature drops quickly when the flow stops in that area.
Hot spots are indicated on the bulk-temperature contour or data-shaded plots during filling. Hot spots are due to excessive viscous heating during the filling stage.
If the maximum bulk temperature is close to the degradation temperature, consider redesigning the part geometry near the hot spot or changing the process conditions.
Differential temperature can also cause non-uniform shrinkage and warpage. 作者: zq_hb 时间: 2003-6-13 14:29
laogui2003 wrote:
::?::?::?Bulk temperature 到底是甚末意思？Bulk temperature 为甚末会在出现Overpacking的地方降低？