Mechanism Design And Optimization Of Absorption Type Automatic Screw Locking Machine

In assembling TV light bar on back board,many non-standard screws with small lengthdiameter ratio are used.At present,that procedure mainly applies manual operation for tightening screws but has problems,such as low efficiency and variable quality.An absorption type multi-axis automatic screw locking machine which solved those problems has been designed and developed in this article.In this article,a multi-axis tightening mechanism scheme has been proposed and the gantry beam structure optimization has been conducted to increase screw tightening efficiency.The structures of electric screw driver front end sleeve and screw feeder have also been studied,the problem of screw jam has been solved and it increases success rate of tightening screws.I.Proposed a multi-axis tightening mechanism scheme.According to geometric features of screw and distribution characteristics of threaded hole of TV back board,three mechanism schemes including single-axis stationary plan,single-axis left-wheel plan and multi-axis plan have been proposed.Each mechanism scheme's mathematical model of efficiency has been established,the optimal multi-axis plan has been applied after comparing these mechanism schemes.The method of combine redundant degree of freedom has been used to simplify the structure of multi-axis mechanism scheme.Several structures such as ball screw with rotary nut and the clutch with pin and hole have also been applied in this scheme which enabled electric screw driver and screw feeder moving simultaneously in x direction.II.Optimization of gantry beam structure.Topology optimization of gantry beam has been conducted,the fundamental structure of beam has been designed depend on the result of topology optimization and the design parameters has been determined based on engineering experience.BP neural network was employed to fit the mapping relationship between design variables and constraint variables which include maximal deformation and first-order nature frequency.The improved particle swarm optimization has been applied to optimize the distribution of the key dimensions of gantry beam,and its result indicated that the weight of the optimized crossbeam reduced substantially.III.Designing of sleeve structure.The evaluation index screw righting and hole finding capability have been introduced in this article.The screw righting experiment compared and determined that vacuum outer sleeve structure has the best screw righting capability.Experiment of screw hole finding capability is further made and its results show that surface vacuum outer sleeve also has good hole finding capability.IV.Solved screw jam problem of screw feeder.Three different plans for solving screw jam problem which is caused by part of screws transversely falling into groove and accumulating have been proposed in this article.The improvement of empting the bottom of groove of screw feeder which has paddle wheel structure has been applied,which reduced the screw jam rate and meet the production requirement.Taking light bar tightening on back board of 43-inch TV as an example,tightening experiments with different moving speeds are made based on hardware platform of sample machine.Results indicated that equipment's tightening efficiency and tightening achievement rate reach the design indices.