一种新近研制的湿砂型冲击紧实造型机以燃烧天然气——空气可燃混合气进行工作。采用5巴的燃烧压力已可获得高铸型强度,其紧实度可以通过燃气混合风机的转速加以控制。冲击紧实的有关特性已用两台这种型式的冲击造型机进行了研究。对紧实速度的重大意义作了验证,证明是研究的最重要成果。在不改变紧实压力的条件下,随紧实速度的提高,铸型紧实的强度和均匀性均大大增加。这一基本规律通过对紧实时强度和压力分布的测量得到反复证实。新设计的冲击造型机被认为特别适于做这些研究,因为其紧实速度易于改变且调节范围很大。紧实速度的影响可以用冲击变型期间振动流态化下膨润土粘性的降低加以解释。由于膨润土微粒间水偶极子的粘结作用可被暂时降低,在冲击紧实的瞬间,型砂可获得更好的滑动性和所有方向上的流动性。试验中研制了简单而又牢靠的压力计。借助于这些仪器可以测量铸型内任何位置的紧实压力。小金属片表面上的压痕尺寸相当于紧实压力,压痕尺寸可以测定且可将其转换为牛顿/厘米~2。压力计亦用在春实和压实型砂试样时紧实压力的测定。在相同的紧实压力下,春砂紧实的试样清楚地表明了具有比压实紧实试样更高的强度。相似的振动流态化现象也在大铸型上得到证实。为了达到给定的湿拉强度,冲击造型机仅仅需要大约60%的压实造型机所需紧实压力。许多压力计可以组合为各种不同的测量仪。有效压力曲线清晰地表示出紧实期间压力的分布。深模板凹坑的压力及底面和侧面压力还表明了振动流态化的作用。冲击造型机因为其高速紧实的缘故,具有各种具体利用由振动流态化所产生优点的可能性,使得铸型的紧实度更均匀,可望获得较高尺寸精度和表面质量以及较低体收缩的铸件。与紧实速度增加相对应的关系如下:1)深模板凹坑内的成型压力超比例地增加;2)铸型背面和分型面之间紧实压力的差异减小;3)侧压力显著增加,在铸型的低层尤其如此。 A newly developed wet sand impact compacting machine to burn natural gas - air combustible mixture to work. With a combustion pressure of 5 bar, a high mold strength is obtained, the compactibility of which can be controlled by the speed of the gas mixing fan. Impact-tight features have been studied with two impact molding machines of this type. The significance of compaction speed has been verified, proved to be the most important result of the study. Without changing the tightening pressure conditions, with the tightening of the real speed, mold strength and uniformity are greatly increased. This basic law has been repeatedly confirmed by the measurement of the distribution of strength and pressure during compaction. The newly designed impact molding machine is considered to be particularly suitable for these studies because of its easy to change the tight speed and adjust the range. The effect of the compaction velocity can be explained by the decrease of the viscosity of the bentonite under vibrational fluidization during the impact modification. As the binding of water dipoles between bentonite particles can be temporarily reduced, the sand gets better slip and fluidity in all directions at the moment of tight impact. The test developed a simple and reliable pressure gauge. With these instruments it is possible to measure the tightening pressure anywhere in the mold. The size of indentation on the foil surface corresponds to the compaction pressure, the indentation size can be measured and can be converted to Newton / cm ~ 2. Pressure gauges are also used in spring and compacted sand samples tight determination of the pressure. At the same compaction pressure, spring sand compacted specimens clearly demonstrated higher strength than compacted compacted specimens. Similar vibrational fluidization phenomenon is also confirmed on the large mold. In order to achieve a given wet tensile strength, the impact molding machine only requires about 60% compaction pressure required to compact the molding machine. Many pressure gauges can be combined into a variety of gauges. The effective pressure curve clearly shows the pressure distribution during compaction. The pressure of the deep template pits and the pressure on the bottom and sides also indicate the effect of vibrational fluidization. Impact molding machines, because of their high speed compaction, have the potential to make any special use of the advantages resulting from fluidized fluidization, resulting in more even compaction of the mold, higher dimensional accuracy and surface quality expected, Low body contraction of the casting. The relationship with the increase in compaction speed is as follows: 1) the forming pressure in the deep template pockets increases proportionally; 2) the difference in compaction pressure between the back and parting surfaces of the mold decreases; 3) the lateral pressure increases significantly , Especially in the lower part of the mold.