The Powder Pressing Principle And Experiment Research For Automatic Sample Preparation

The product quality of cement, metallurgy, chemical industry and pharmacy fields isdecided by their chemical composition, so composition examination and the test technologyhave very important implications in these industries. As a method of compositionexamination, X-ray fluorescent analysis has been widely used because it has so manyadvantages such as the more kind of analyzed materials, preciseness and quickness, the easyoperation and no damage to the materials composition. Before the fluorescent analysis, itneed to prepare the sample by the powder pressed-disk technique. Currently, in our countrybefore the powder is pressed to the sample in sample pressing machine, the raw materialsfirstly need to be crushed in the vibration grinding machine. But this method need to becompleted in two separated machines, wasting more time and having the low efficiency andautomatism, as well as the large labor intensity. Based on the powder compression principleresearch for the sample, this paper has proposed one kind of sample preparation machine toautomate to produce the sample and also completed the experiment research. This machinehas ensured the sample process are more precise and quicker, and the quality are more better,consequently it has improved the accuracy of the test result for fluorescent analysis.The research has been mainly carried on in below aspects:1. Firstly, this paper has analyzed the research situation at home and aboard about thevibration grinding machine and the sample pressing machine. Combined with the researchsituation, the automatic sample pressing machine having the functions of grinding andpressing has been designed to manufacture the sample for fluorescent analysis with theadvantages of easy operation, preciseness and quickness and full automation.2. The theory research and simulation analysis have been done to sample pressing andgrinding machine. The key component in this machine is the vertical vibration roll-mill ofsuperfine comminution, the performance of which will directly affect accuracy of theultimate sample test result. Consequently, it is very important to deeply research the verticalvibration roll-mill. At first, this paper has studied the grinding theory about the vibrationroll-mill and established the equivalent mechanical model of the medium in the grindingbowl, analyzing the roll-mill motion in the horizontal direction as well as the motion of themedium in the grinding bowl. Then, based on the theory analysis, the simulation model ofthe vertical vibration roll-mill has been established using the Muti-bodies Dynamical software RecurDyn. From the impact force perspective, this paper has investigated the effectregularity about the dynamical parameters to the impact force which is relative with grindingeffect and efficient in the grinding bowl, providing theory foundation to subsequentlyimprove the characteristics of the vibration roll-mill machine.3. Structure analysis has been done for the automatic sample pressing machine. Thedeformation for the matrix of pressing sample have a significant effect on the surface of thesample. Consequently, the paper has analyzed the lateral stress of the matrix of pressingsample in the below mould for the pressing sample. According to the principle that theelastic deformation cannot exceed the permissive limit of the pressing roughcast precision.At the same time, it has studied the stiffness and intensity of matrix by the finite elementmethod, the results of which have ensured that it cannot produce the fracture and bulgingcaused by the deformation. As the sample pressing machine can generate30t pressure whenit compress the cement sample, this paper have carried on the static simulation analysis tothe sample pressing machine, ensuring the reliability of this machine and optimizing thestructure which has the concentration of stress.4. This paper has studied the whole structure about the automatic sample pressingmachine, introducing every component of this machine. The feed mechanism, thequantitative feeder, conveying mechanism have been investigated in details. Moreover, it hasdeveloped the hydraulic system.5. The experiment research has been completed for the designed sample pressingmachine. The crashing performance of the vertical vibration roll-mill is investigated inexperiment, the result of which have indicated that the sand particle diameter about6-18meshes can be grinded to200meshes above in defined time,with cement raw materialsgrinding to200meshes above in short time, even more than500meshes and this machine isequipped with good crashing performance. Then the cleaning experiment for the machinehas been carried on, and the results have indicated it has the wonderful cleaning and goodsealing performance. At last, the sample pressing has been tested in this sample pressingmachine. It has defined the performance of the pressed sample are more better when thepressure is30t and the pressure holding time is15s through analyzing the effect of pressingpressure and holding time to the sample test. In addition, the pressed sample is tested in thefluorescent analysis equipment and compared with the sample pressed by the cementfactories. The test results have indicated that the products manufactured by this samplepressing machine meet the test requirements with good compactness performance and the highly polished surface.