Design And Research Of Automatic Flexible Fixture For Benchtop Precision Machine Tool

With the increasing demand for smaller processing systems in aerospace,military and other high-tech fields,desktop factories have attracted more and more attention.As an important part of desktop factories,benchtop precision machine tools have become the key research object of manufacturing industry to adapt to market changes.It is mainly used to process some small parts with complex structure and high processing quality,and they generally have single-piece,multi-variety,and small-batch production characteristics.Processing these parts,the machining system should be flexible enough,especially the fixture.At present,most of the small fixtures are not flexible and automatic,and most of them adopt the experience design method with low efficiency and unstable quality.To solve these problems,this paper makes full use of computer-aided technology to design a small-scale fixture for automatic and flexible clamping of small annular thinwalled parts,studies the optimal design method of the fixture,and develops a prototype for relevant experiments.Aiming at the problem that small annular thin-walled parts are widely used but difficult to clamp,an automatic and flexible workpiece clamping scheme based on axial clamping is proposed.By analyzing the clamping characteristics of typical workpiece,the corresponding clamping scheme is designed,and the correctness of the scheme is analyzed by mathematical modeling method.According to the requirements of automation,flexibility and precision of the fixture,the structure of the fixture is designed,including the positioning and clamping mechanism which can realize two coordinate movement and single coordinate rotation,and can theoretically realize the flexible and automatic clamping function.Based on the weak stiffness of thin-walled parts,this paper makes a detailed analysis on how to reduce the clamping deformation of these parts,and establishes the finite element dynamic and static analysis model of the clamping system by ABAQUS.The clamping scheme,the topological structure and the vibration characteristics of the fixture are optimized.The analysis value of workpiece clamping deformation is controlled at the micron level,the volume of the clamping system is controlled within the range of ?120 mm × 120 mm,and the anti resonance ability of the fixture is enhanced.Considering the actual application of the fixture,this paper uses VERICUT to simulate the real machining environment,and uses CAXA to make complex machining programs of typical parts to detect interference between tool and fixture,then adjusts the structure of the interference area of the fixture to ensures the usability of the fixture at the early stage of the fixture design.Finally,the construction of the prototype is completed.The fixture adopts a clamping implementation scheme of stepper motor and screw drive,contact positioning,and clamping force control.The designed fixture prototype can achieve micron-level positioning accuracy.