| The pulp-molding product can be out of wet, mildew, water, oil and static electricity; it also has such advantages as heat-resistant, nontoxic, flavorless and good cushioning character. Therefore, pulp-molding product has been one of the best substitutes of EPS (Expendable Polystyrene) to deal with the "white contamination" at present.On the basis of the summary and analysis of current advance of manufacture techniques, product technics and equipment of pulp molding, the problem, handicap of research and development of pulp molding production were put forwarded as well as the countermeasures.The basic theory related to the pulp molding product manufacture and technique flow was studied in this paper, which includes the theological behavior of low consistence pulp, the design theory of transfer system of pulp, the mechanism of mold heating, etc.The Theological behavior of low consistency chemical pulp of bagasse and the mixed pulp (90% mechanical pulp of Chinese fir and 10% sulfate pulp of Masson pine), the result shows that the apparent viscosity of the two kinds of pulp was changed with the temperature, degree of beating, pulp consistency and shearing velocity. The rheological model was also set up, which shows mat the liquid type of the low consistency pulp can be assorted to the pseudoplastics liquid (non-Newtonian). Based on the results, the friction loss of pulp transfer system was calculated as well.The mechanical system of product line of packaging container of pulp molding was analyzed, which includes the molding device, mold-heating device and materiel-transferring device. The pneumatic system was designed by the way of signal-action state graph. Particularly, the optimum design of loaded beam that is one of the key devices of materiel-transferring system was carried out by the way of multiple-object optimum. Compared with the original design, the optimum design can make the weight of beam lower, the collocation of supporting fulcra more reasonable and the system more stable.With the analysis of the mold-heating process, the partial differential equation of heating conduction of mould was set up and calculated by mathematical and numerical methods (infinite element method) respectively, the heating time was deduced by the solution of the partial differential equation combined with the conclusion of actual experience during process, which provide the theoretical basis for the design of the control system of the product line.Take the process of 600mL tableware of pulp molding for example, the orthogonal experiment was carried out. And the optimum technical parameters were selected by the analysis of square difference for the experimental result which shows that the pulp consistencyand beating degree affect the weight of the final product and the water content of rough product before the mold-heating procedure markedly, the optimum parameters of 600mL tableware made by mixed pulp are as follows: 25°SR of beating degree, 2.5s of absorbing time,68mmHg of vacuum degree and 0.4% of pulp consistence, as for those of the chemical bagasse pulp are as follows: 20°SR of beating degree, 1.5s of absorbing time, 590mmHg of vacuum degree and 0.4% of pulp consistency. The parameters of technical process provide the basis for the control system layout as well.The relationship between the product quality and the parameters such as pulp consistency, vacuum degree, and temperature was analyzed. According to the process techniques and the equipment characteristics, the fuzzy control system of the product line was designed combined with the result of experience of the actual process. In this control system, Omron PLC was selected as the core of the control system; proximity switch as detect units and the running program was finished by the time order figure. The product line runs stably, the fuzzy control system was also reliable, but the cost of it is low relatively.In conclusion, the improved layout of the product line make the productivity higher, the quality better, the ratio of waste product...
|
PDF Full Text Request