Structural Analysis Of Number Control Machine For Stranded Wires Helical Spring

Stranded Wires Helical Spring, also called multi-wire helical spring, is normally made up of several steel wires (usually warped by 2~16 carbon steel wires with 0.4~3 mm radius) that are tied up to form a strand with the same direction of spiral, the strand is then twisted to form a helical spring. Taking advantage of its predominant characters such as better stiffness, higher strength, longer fatigue life and more effective shock absorption compared with single-wire helical spring, Stranded wires helical spring has important application in the shock absorber of the automobile instruments, the armament blast-off system and aeroplane engine etc. Furthermore, it also has important and potential value in civil use.However, its wider use is limited to some special fields by its high structure design requirement, complicated manufacturing process and difficult quality control. Big machining error, low product precision and high rejection rate (which is even to the point of 80%) always occur owing to the incorrect modeling of the mathematical model and unreasonable design of the machine, rendering the tough further research and high manufacturing cost of this particular spring.Previous mathematical model of closed-end spring requires complicated programming tasks and can't guarantee the processing accuracy, even worse, conventional processing method or current numerical control machine consumes a long-time machining cycle and tediously manual work, such as long time taken up by drawing wires, frequent twist-off of the wires during processing for the defective machine design and ineffective tension control system.On account of its high design requirement and complicated manufacturing process, and aiming at overcoming the defects mentioned above, this paper establishes a mathematical model of closed-end spring, The simulation of the centre line and its expanding model are carried out by PRO/E. Compared with other previous mathematical models, the result corresponds to the design and actual processing requirements obviously, realizing parametric modeling of closed-end stranded springs as well.To realize four-axis simultaneous motion among the middle-layer twisting shaft, outer-layer twisting shaft, turn-screw and reeling shaft, on the basis of the manufacturing principle and machine structure, the whole system adopts PC+PLC control structure to solve the synchronization control of the four servomotors during reeling, which includes host computer (PC), PLC module, the actuators (servo drivers and servomotors), the controlled objects (five shafts) as well as the cables between them for transferring data.According to the processing characteristics and modeling of closed-end stranded springs, a novel scheme design scheme for the manufacturing machine is provided, which has overcome the drawbacks of the traditional machine and previous numerical control machine. Then, for the sake of appraising the feasibility of the machine design and the machining characteristics of the machine, feature modeling, virtual assembly and motion simulation are carried out in the environment of PRO/E. Regarding to the structure complexity and multitudinous components of the machine, by using animated technique and simulating analysis function of PRO/E, mutual interference between moving machine components can be checked efficiently. During the simulation, the whole process of machining can be shown in 3D view, the results of which show that this scheme is valid in aspects of parts shape design and satisfaction in the kinetic requirements. In addition, by 3D motion simulation, the machine's motion and the design validity of the closed-end spring are verified.Finally, critical components of the machine is analyzed by finite element software ANSYS, and the intrinsic frequency and the vibration model is gotten, it is calculated the working speed of axis was far away from it's limited rotate speed, which could avoid the region of sympathetic vibrations effectively.