Szwajka Krzysztof, Szewczyk Marek, Trzepieciński Tomasz
Department of Integrated Design and Tribology Systems, Faculty of Mechanics and Technology, Rzeszow University of Technology, Ul. Kwiatkowskiego 4, 37-450 Stalowa Wola, Poland.
Department of Manufacturing Processes and Production Engineering, Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, Al. Powst. Warszawy 8, 35-959 Rzeszów, Poland.
Materials (Basel). 2022 Dec 21;16(1):28. doi: 10.3390/ma16010028.
In the compaction process, an uneven densification of the powder through the entire height of the die is a major problem which determines the strength properties of the final product, which vary throughout the entire volume. The aim of this investigation was to determine the distribution of the forming pressure inside the die and to visualise the differences in compaction. To determine the pressure inside the die during the compaction process, the deformation on the die surface was measured by means of strain gauges. However, in order to visualise the densification of high-silica sand during the compaction process, an X-ray tomograph was used, which permits one to visualise the interior of the die. The authors developed an analytical model of how the change in internal pressure influences the change in stresses arising on the outer surface of the die, and, as a result, the friction force. It has been observed that the highest values of pressure as well as the highest concentrations of the loose medium are found closest to the punch and decrease with distance from the punch. Moreover, based on the measurements of deformation, a dependence of the pressure distribution on the value of friction forces was observed, which prompted further analysis of this phenomenon. As a result, tests to determine the coefficient of friction between the die and the loose medium were carried out. This made it possible to describe the pressure distribution inside the die, based on the pressure applied and the height of the die.
在压实过程中，模具整个高度上粉末的不均匀致密化是一个主要问题，它决定了最终产品的强度性能，而强度性能在整个体积内是变化的。本研究的目的是确定模具内部成型压力的分布，并直观呈现压实过程中的差异。为了确定压实过程中模具内部的压力，通过应变片测量模具表面的变形。然而，为了直观呈现压实过程中高硅砂的致密化情况，使用了X射线断层扫描仪，它能让人看到模具内部。作者建立了一个分析模型，以研究内部压力的变化如何影响模具外表面产生的应力变化，进而影响摩擦力。据观察，压力的最高值以及松散介质的最高浓度出现在最靠近冲头的位置，并随着与冲头距离的增加而降低。此外，基于变形测量，观察到压力分布与摩擦力值之间的相关性，这促使对该现象进行进一步分析。结果，进行了测定模具与松散介质之间摩擦系数的试验。这使得基于施加的压力和模具高度来描述模具内部的压力分布成为可能。
