| As one of the Stamping’s three main constitutes (Stamping Process, Stamping Die,Stamping Equipment), stamping equipment determines product quality and production rate.With the development of society and the demand of diversified products, conventionalMechanical Presses are unable to meet the requirements of processing flexibility, highproduction rate, energy saving and environmental protection. Therefore, it is imperative todevelop new type of Presses. With the advent of high-power AC Servo Motor and theimprovement of CNC Systems, it is possible that a Press has high-power Servo Motor,controlled by Numerical Control System that directly driving the slider.CNC Servo Pressappears under thisbackground. Comparedto conventional Mechanical Presses,CNC Servopress has many advantages, such as nice processing flexibility, high precision, highproduction rate, low noise, energysaving and maintainingconveniently.In this paper, a specificmethod is proposed for the developmentof a new CNC ServoPress, which is based on the comparative analysis of motion characteristics of the fourtransmission mechanismand finite element analysisof frame. The contents of thisspecificresearch are as follows:1. The work characteristics and working principle of the250tons conventionalMechanical Pressand250tons CNC Servo Press are discussed.2. Using the motion analysis software ADAMS as research tool, the analysis isparticularly focused on the motion characteristics of toggle link transmission mechanism,symmetric toggle link transmission mechanism, symmetrical double toggle linktransmission mechanism, and symmetrical triangle toggle link transmission mechanism.Under setting conditions, the curves of displacement, velocityand force of the transmission mechanisms mentioned are obtained respectively. Comparative analysis found that thesymmetrical triangle toggle transmission mechanism has a good power performance,smooth movement and high structural rigidity. Therefore the symmetrical triangle toggletransmission mechanism is taken as the transmission mechanism of the250tons CNCServo Press.3. The frame of250tons CNC Servo Press is designed based on the frame of the250tons conventional Mechanical Press and transmission mechanism that conforms to theassembly relation with250tons CNC Servo Press is created. The solid model ofsymmetrical triangle toggle link transmission mechanism is assembled with the framedesigned anda prototype model of the250tons CNC Servo Press is obtained.4. Using the finite element analysis software ANSYS as research tool, through finiteelement analysis of the frame of the250tons CNC Servo Press, the data of stress anddisplacement distribution of the frameunder the worst condition, the naturalfrequency andvibration mode of the frame are obtained. The data shows: under the static load, maximumdisplacement appears in the beam back shaft. The maximum is0.439mm; Maximumstressappears in the beam back shaft andcorner of stand column and pedestal.The maximum is197MPa. The lowest modal frequency is21.633Hz. The maximum stress is below yieldstrength of frames’material Q235A andthe lowest modal frequencyis higher thanworkingfrequencyof slider,therefore therationality of the framestructureis verified.5. The maximum stress is close to the materials’ yield strength under static load andthe lowestfrequencyof frame is veryclose to20Hz. Frequency of infrasonic wave islowerthan20Hz, under which condition, workers are easily fatigued. To solve above problems,this paper proposes several structure improvement measures, which reduce the stress levelof the frame. After verification of finite element method, improving measures can alsoeffectivelyincrease minimum modal frequencyof theframe. |
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