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layer. T2 is the temperature after the layer lost its heat to the
air while T0 is the initial temperature before the layer is
heated by laser. It is obvious that T2 is not equal to T0, and
T1 is higher than T2. Therefore, heat from a current layer will
transmit to the previous one, i.e., the heat from the previous
layer will be sealed by the new one coming for T1>T2, and
the direction of heat flux between the two successive layers
will point to the previous one. Increasingly, heat will be
accumulated layer by layer, and the temperature of the
whole SLS green part will become high enough to raise the
risk of binding the extra loose powders outside the process
cross-sections.
Shown as Fig. 4, cooling channels have three positions
according to the relationship between the axel of the channel
and the Z axis. Their positions are perpendicular, parallel, and
the position which is between other two ones, respectively.
Cross-sections of the channels are surrounded by heat flux
from circumference of sintered sections (Fig. 4a–c), and it is
different according to the different relationship between
channels and laser beam. Such heat accumulation and
transmission will induce the excessive temperature augment
over the softening point of epoxy powders within the closed
zones where the unsintered powders are. Among these three
position relationships in Fig. 4, loose powders in the channel
whose axel is in parallel with the laser beam has the most
probability of being binded. That is because the heat accu-
mulation and transmission will become larger under such
conditions that the area of the channel cross-section is
smaller in Fig. 4c than those of the other two ones in Fig. 4b
and Fig. 4a, respectively, and there are more layers needed to
be built-up to finish the whole channel in Fig. 4c than those
in Fig. 4a, b. The channels are blocked when loose powders
are binded additionally.
The precision of the green part will be damaged if the
extra loose powders are binded on the surfaces of the part.
Therefore, the forming procedures and the corresponding
parameters should be adjusted to avoid the extra binding
problem. One creative method is to change the combination调查研究间接选择性激光烧结制造注塑模具
摘要：对于提升注塑塑料部件生产的速度和质量注塑模具的冷却系统是很重要的。随形冷却水道是新开发的温度调节方法用来推动冷却系统的效率。他们可以在注塑模具中通过间接选择性激光烧结结合传统的粉末冶金来完成。这项工作探讨一些过程像热传输，粉末除去，和在模具镶件的制造中金属熔体渗透的细节。结果表明，激光扫描的区域外多余的粉可能是由于烧结在一起的烧结零件在烧结过程中激光能量的积累所造成的。这是在一层被烧结后对初始层切换温度解决的。当未烧结的粉末在冷却通道进行去除时，根据一定的力量真空的极限长度系统就会出现。因此，一些使冷却通道通向外部的子通道是用来帮助去除冷却通道内的粉末的。在金属液渗透过程中采用滴落法，这被证明是与保持金属液渗透最终形状相关的。论文网
关键词：选择性激光烧结。注塑模具。随形冷却水道。制造细节