| Forming machine, the important manufacturing equipment, is one kind of majorequipment in the fields of automobile, electrical machinery, instruments and meters, defenseindustry, etc. With the advantages of high flexibility, intelligence, high efficiency, highprecision, and environmental protection ability, servo press will become a main developmenttrend for forging machine in the future. In recent years, the research and product developmentof servo press go more and more widely and deeply in domestic, and have already achievedmany breakthroughs. Hence, the main direction of this thesis is the research of the preparationkey technology of servo press, and focuses on researching deep drawing process curve.Systematic research is in three directions as follows: process curve planning, servo motorcontrol strategy and programmable servo drawing.Nowadays, the poor process performance of domestic servo press makes it difficult torealize servo deep drawing and to guarantee the quality of products. In order to overcome theshortcomings mentioned above, in this paper, servo drawing curve was planned; for14301stainless steel cylinder and DX530D galvanized steel shell, servo simulation analysis andexperimental research were conducted on the deep drawing; and servo control software wasdeveloped to control the deep drawing process. Then the validity and rationality of the servopress servo drawing process was verified by experimental research.The main research contents and conclusions of this paper were summarized as follows:(1) The slider-crank mechanism performance of servo stamping equipment and the multilinkage mechanism performance of general equipment were analyzed and compared; thekinematics and dynamics analyses of slider-crank mechanism were done; and servo controlsystem, ac permanent magnet synchronous motor, servo drive hardware experiment platformand current control were studied in the control part; and then the technical parameters of theservo press were concluded. So the servo crank press with slider-crank mechanism couldrealize the work performance with controllable slider speed and long working stroke. Thus,eventually the servo press could realize variable speed stamping forming process, and couldimplement a stamping mechanism to carry out varieties of stamping process.(2) In view of the torque output characteristics of high power low torque servo motor, basedon current control, the control strategy was studied, and servo control system for stampingprocess was developed. It realized the efficient control of speed and steering, and greatlyimproved the flexibility, accuracy and reliability of the servo stamping process. The resultsshowed that using high power low speed servo motor drive control system, the permanent magnet synchronous motor with the characteristics of fast switching speed, reverse speed andbetter variable speed, through the motor angle and rotational speed control, could realizeslider accurate positioning and variable speed driving, and could make the servo press satisfythe application of industrial stamping production.(3) Through analysis and research of deep drawing process combining with servo stampingtechnology, the key factors affecting the servo deep drawing were found. Combined with thedeformation rate and friction coefficient, the deep drawing process curve for servo stampingwas programmed. To the key factors affecting the quality of servo deep drawing, threeimportant performance indexes were determined: the material parameters, drawing speed, andcurve model. Through analyzing the other factors affecting curve planning, the piecewisepolynomial mathematical model was established, and the servo deep drawing process freecurve model was determined. Stamping slider displacement was divided into three regions,five stages. Combined with the mechanical property of the press, the material servo drawingcharacteristics, curve fitting method, and the constraint, the key node selection criterion wasconcluded. According to the selecting criterion, the servo deep drawing process curve wasplanned. Based on three order polynomial function and three order curve interpolation fitting,and analysis of the free curve model in servo deep drawing technology, three suitable curves(similar cosine, ladder and ladder oscillation) for deep processing were planned. All theseprovided a theoretical basis for the servo press stamping technology application, and theproduction and processing which were depended on the development of softwareprogramming.(4) Based on numerical simulation, the forming quality of cylindrical and car shell parts wasstudied. The drawing simulation was made by using offset cosine curve, similar cosine curve,ladder and the ladder oscillation curve drawing. The key nodes of typical ladder oscillationcurve had solved. The explanation of the concrete calculating examples had been given. Andthe forming limit diagram, stress-strain and thickness reduction ratio were analyzed andcompared. At last, the suitable curve for deep drawing process was determined. Throughfurther optimization and simulation tests, the deep drawing process curve which met theexcellent conditions was obtained, and this also made preparations for future deep drawingtechnology research.(5) For the purpose to control the deep drawing quality and to improve the processprogramming parameters, using.NET as a platform and visual studio tools, servo stampingdrawing software was researched and developed. A software structure of PC and servo drivehad been established to realize the servo stamping drawing software function of motion control system, parameter settings, manual function module, machining simulation, etc.According to the1100KN servo crank press process curve planning, custom functions, likemodifying stamping parameters of the servo press mode, could be realized in software.Through the process programming, different curve motion control was implemented, and amore reasonable deep drawing process curve was provided for subsequent processingtechnology.(6) Based on the product’s processing, the deep drawing mould was designed andmanufactured. With servo stamping equipment, experiments were carried out on thecylindrical and shell parts in actual processing situation. Three key technologies--servoprocess curve planning, servo drives control strategy and programmable servo drawing weretested and verified. For complex forming product, the planning free curve model couldimplement a scientific drawing effect under the conditions of servo and programming. Thequality analysis of deep drawing part products showed that the effect of servo deep drawingcurve was better than the effect of cosine drawing curve in respect of thickness and shape.Tests verified that the servo press system was reasonable, practical, stable and reliable, andprogramming function of the deep drawing process curve was fast. Through programmingand machining the servo drawing process curve, deep drawing performance was improvedmarkedly; and deep drawing quality was improved too. Thus, it provided a solid foundationfor the application of the servo press stamping key technology and equipment in practicalproduction. |
PDF Full Text Request