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砂型内应力分布的研究,对于揭示型砂压实紧实机理和高压造型砂箱设计参数的选择是十分必要的。本文采用了电阻应变式压力传感器,测定了砂型内应力分布及其影响因素,还测定了砂型残留旁侧应力及其影响因素。根据实验得出:压实比压增加,型内各点应力都随之而增加。当比压较低时,旁侧应力呈斜直线分布;当比压升高后,砂型的中下部旁侧应力明显增加,使应力曲线中间一段应力差变小,曲线两端倾斜增加。砂型高度降低,旁侧应力值增加;模型高度越高,旁侧应力越小(除高模型的上部外)。型砂的各种成份主要通过紧实率来影响型内应力分布。含水量低、粘土含量高、煤粉含量高的型砂,型内应力呈较均匀的分布。反之,型内应力分布不均匀。文中还讨论了紧实率、模型高度、砂型高度及煤粉含量,对残留旁侧应力的影响。
The research on the distribution of internal stress in sand mold is very necessary to reveal the compaction mechanism and the design parameters of high-pressure modeling flask. In this paper, the strain gauge pressure sensor was used to determine the distribution of internal stress in the sand and its influencing factors. The residual stress and its influencing factors of the residual sand in the sand were also measured. According to the experiment, it is found that the compaction ratio increases and the stress in each type increases. When the specific pressure is lower, the lateral stress is obliquely distributed. When the specific pressure is increased, the lateral stress in the middle and lower parts of the sand mold increases obviously, so that the stress difference in the middle part of the stress curve becomes smaller and the inclination at both ends of the curve increases. The sand height decreases and the lateral stress increases. The higher the model height, the smaller the lateral stress (except for the upper part of the high model). Various components of sand mainly through the compaction rate to affect the type of stress distribution. Low moisture content, high clay content, high coal content of sand, the type of stress was more evenly distributed. On the contrary, the stress distribution within the uneven. The paper also discusses the influence of the compaction rate, model height, sand height and pulverized coal content on residual lateral stress.