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冲击造型时可用两种方法紧实型砂,气体不膨胀和不加速,在气体静压力作用下,型砂被紧实;在气体爆炸膨胀或空气燃气混合气体爆炸时,在气体分子的惯性作用下紧实型砂。采用第二种方法紧砂所用装置如图1(1)所示。喷嘴使气体加速并在砂箱面积上均匀分布,预先蓄积的压缩气体(一般是空气)当箱体打开后就突然膨胀,并开始流动。压力在0.4～0.6MPa 时的膨胀速度达到400m/s,当压差在几十个大气压时,膨胀速度远远超过音速(331m/s)。
Impact modeling can be used to tighten the sand in two ways, the gas does not inflate and not accelerate, under the effect of gas static pressure, the sand is compacted; gas explosion or air-gas mixed gas explosion, the gas molecules in the inertia of tight Real sand. The second method used tight sand equipment shown in Figure 1 (1) below. The nozzle accelerates the gas and distributes it evenly over the area of the flask. Pre-accumulating compressed gas (usually air) expands suddenly and begins to flow when the body opens. When the pressure is 0.4-0.6MPa, the expansion rate reaches 400m / s. When the pressure is several tens of atmospheres, the expansion rate far exceeds the speed of sound (331m / s).