Research On Automatic Mechanical Polishing Technology And The Process Optimization For Stainless Steel Thin-wall Material Workpieces

Stainless steel thin-wall household appliances are widely used in our daily life, like electric kettle, dripolator, electric food warmer, and service plate, etc., which have a broad market prospect. Polishing is the most important procedure when processing the appliances. It’s necessary for the surface material to be removed evenly with low roughness level, workpieces of stainless steel thin-wall materials are tend to burn, to transform, and hard to clamp during polishing. It’s not easy for the material to be polished. So far, automatic polishing technique for home appliances of stainless steel thin-wall materials are lack of further study in the research institutes in China, and more over, there are some limitations in the few present equipments, which are not available for the wide use of home appliance polishing industry. At present, manual polishing is still mainly applied in home industry, which not only results in such problems as poor quality, low efficiency,.serious pollution and being short of hands, but also severely restricts the development of such industry.Among stainless steel household appliances, electric kettle is typical for its relatively complex shape. So, this thesis mainly focuses on electric kettle polishing:in connection with the real productive background of the electric kettle of stainless steel, and in frference to the lack of equipment, this thesis studies a set of high-efficient automatic mechanic polishing technique fit for stainless steel electric kettle polishing as well as develops a corresponding mechanical polishing machine tool and automatic control system. This research is important for improving the present manual method which is widely used in our electric kettle polishing and the same type of other household appliances industry.Firstly, for stainless steel parts, setting up a theoretical module of surface material removal rate and a module of surface roughness of workpiece supplies a theory basis for automatic mechanical polishing technique.(1). applying theories of elastic mechanics and abrasive grinding in setting up a module of surface material removal rate proclaims, from the microscopic point of view, the relation between abrasive particles with its related process parameters and material removal rate. The models show, material removal rate is in proportion to mold rotating tangential velocity, workpiece peripheral velocity, feeding speed of workpiece as well as normal polishing pressure parameters, and has non linear relation with die granule size and its structure.(2) the setting up of the module of the relation between surface roughness of workpiece and polishing process parameters, based on the method of regression analysis and orthogonal test, proclaims that the roughness of the work surface grows with the increase of polishing pressure, workpiece peripheral velocity as well as feeding speed, and reduces with the increase of the mold rotating tangential velocity. Applying the method of mathematical simulation and experimental validation to the study and analysis, we can see the fine consistency between simulation and experiment, which proves that the two methods of setting up modules are correct, and which has a directive significance in making rational planning for automatic mechanical polishing technique.Secondly, to meet the demand for highly efficient polishing, this study suggests a kind of automatic mechanical polishing technique for multi-position and multi-abrasive tools, which can respectively polish both external surface and internal surface of the workpiece. The key technique includes structure designs for polishing machine tools of multi-position and multi-abrasive tools, designs for multi-station shapes synchronizing controls, and designs for workholders. And based on this technique, a corresponding automatic control system for mechanical polishing machine tools of multi-position and multi-abrasive tools is designed. According to the fact that real productive process needs the self-adapting of the abrasive tool to the forms of workpiece, a method based on lead-through teaching for the data generation of polishing tool positions is proposed to be used in the automatic polishing system.Thirdly, in the connection with the existing polishing technique, it proposes a set of methods fit for the automatic mechanical polishing technique for stainless household appliances. By making respective programs according to the characteristics of the surface shapes of household alliances, it has designed an automatic mechanical polishing plan, which adopts spiral polishing tool-path as the path of the polishing tools, and it also has studied the tool path data computing methods. Through a series of experiments and with the help of the existing polishing experience, it provides a set of process fit for the technique of rough polish, half-finishing polish, and finishing polish in automatic mechanical polishing of household appliances.Fourthly, under the premise of the polishing quality being ensured, it tries hard to raise the working efficiency so as to optimize the experiment research on the automatic mechanical polishing technique parameter. By using the orthogonal experiment method, and taking material removal rate and surface roughness value respectively as the aim, the best combination of process parameters has been received under the given test condition. Experiment shows that workpiece surface material removal rate is in proportion to normal polishing pressure, mold tangent speed, workpiece peripheral velocity and feeding speed of workpiece; while, though the surface roughness is in proportion to normal polishing pressure, mold tangent speed and feeding speed of workpiece, it is inversely proportional to mold tangent speed.Fifthly, according to the research above, the batch experiment, by making good use of the best combinations of process parameters, is made on polishing electronic kettle on the mechanical polishing machine tool with multi-position and multi-abrasive tools, which shows that the quality of the polished surface of the workpiece is uniform and the value of the roughness is low, which meets the enterprise quality requirements with no pollution in the productive process and with the working efficiency being3times as high as the one of manual polishing, and proves the validity and superiority of the method of automatic mechanical polishing with multi-stations and multi-abrasive tools.