Research On High Dynamic Response Characteristic Of Electronic Shogging System For Warp Knitting Machine

High-speed warp knitting machine occupies an important position among warp knittingequipments, due to its efficient production and widely applicable field. The fullycomputerized process of high-speed warp knitting machine has been pushed with the rapiddevelopment of electronics and servo control technology according to the need for multi-variety and small batch of the production. However, because of the complicated overlapmotion and high frequency, the high level control of shogging movement of guide bar isdifficult. Digital control for shogging movement becomes a bottleneck of the fullycomputerized procedure of high-speed warp knitting machine. China owns85%of the warpknitting machines of the world and the machines in abroad with general electronic shoggingmovement have been speeded up to1400r/min, while there are no kindred mature products inour country. Based on this technology situation, in this subject, the writer focuses on theinvestigation to high dynamic electronic shogging system of warp knitting machine.Firstly, according to the production structure analysis of high-speed warp knittingmachine, the superiority characteristic of the products was defined as mini jacquard andbig circulation. Therefore, the more flexible changing of tissues and larger storage ofpattern information are required to feed the need of product structure. Through the motiondecomposition of the shogging and swing of guide bar, the shogging features and controldemands obtaines----high frequency, high accelerometer reciprocating start-stop and highprecision, micro distance linear positioning. To verify the dynamic stability of the system, theguide closure mechanism, lead screw transmission mechanism, AC permanent magnetsynchronous servo motor and feedback control links were modeled separately. The influenceonto positioning deviation given by mass of bar and the equivalent stiffness of system were aswell as analyzed. Then the integral dynamical model was established based on the separatedmodels mentioned above. Meanwhile, simulink was employed to simulate the system modeland step excitation. The results showed that increasing the system gain in a certain range orchanging the transmission stiffness value would lift the response frequency of system.However, when the gain value was adjusted to a certain degree, the system steady-state errorincreased and dynamic response results went worse since the system resonance frequency wasclose to its natural resonance frequency.Secondly, through the analysis and comparison of the dynamics parameters of simpleharmonic motion characteristic of high-speed cam mechanism, no stay modified trapezoidalacceleration strategy was chosen to guarantee, the speed, acceleration and jerk of motor wereunder lower motor capacity. After the comparison of response features of the different controlmodes, the one with high frequency acceleration and accurate positioning features was chosento achieving bi-target requirement with bigger acceleration start and high precision locating.Then electronic cam motion control algorithm was deduced to realize the coupling betweenno stay modified trapezoidal acceleration curves and process curves. Moreover, the algorithmand steps of static and dynamic electronic cam data tables were obtained.Afterwards, three-tier architecture from the bottom to the top was established by using bottom-up order. The optimized lowest exercise executive level was composed by highprecision ball screw transmission system and low inertia servo motor. The medium movementexecutive level was constituted by semidetached movement controller based on PCI withutilizing DSP+CPLD. In the movement management level, the software modules aboutdynamic loading of oversized tissue height and blackout-breakpoint continuation were the keyof designs. Then the research and development as well as function realization of the wholehigh dynamic response electronic shogging movement control system was achieved.Finally, the contrast experiments were implemented based on the established high-speedelectronic shogging system to test and verified the response performance. No stay modifiedtrapezoidal acceleration strategy and speed/position hybrid control strategy was verified. Onthe machine of E32type, to achieving overlap with one gauge just cost8.3ms could satisfythe requirement of expected dynamic responses, which was speeder than other accelerationand control strategies. By utilizing acoustic vibration tester to implement the equivalentelastic quality body modal analysis on the mechanical transmission mechanism, the naturalresonant frequency of bar transmission mechanism was12.5HZ, and the correspondingrevolving speed of the main shaft was750r/min. That was to say, the resonance region existed,but it was not in workspace. Thus, the selected transmission mechanism, like lead screw, metthe requirements of production speed as1200r/min. At last, through the on-line Byrd figureanalysis of motors and lead screw transmission mechanism, it was can be known that theresonant frequency was about2KHZ. Utilizing electronic notch filter to restrain systemresonance and improving system dynamic response performance were proposed. Themechanical resonance, like noise of screw nut, has been filtered by employing notch filter.Under the condition with wonderful resonance suppression, the dynamic response of thesystem has been elevated again to match the main shaft speed of1300r/min.