Study On Method Of Designing Flexible Fixture Orient To Shoe Last Workpiece With Free Curved Faces

As shoemaking industry and a new individualized shoemaking industry develop, polytechnic has increasingly more discriminating in regard to clamping of shoe last applied in traditional shoemaking procedures. The traditional adjustable fixture for shoe last has already become a pressing bottleneck problem for their restricting the automation and flexibility production capacity. According to the technology background and based at CAD model of shoe last, the paper presents a deep research in design method of flexible fixture to shoe last's free curved surface workpiece.A effective method based on secondary exploitation of CATIA for extracting information from shoe last surface is proposed in the paper as following: Directing toward shoe last, a positioning and clamping scheme is proposed, and then the optimization design is carried out; lastly by using self-adapting reconfiguration metamorphic mechanism conducts creation design of flexible fixture, a new flexible fixture is developed to fit the flexible production requirement in modern shoemaking system. The main parts in this thesis as followings:1) Firstly the formal methods of computing the curved surface information are elaborated, by analyzing their disadvantages, directing toward shoe last components which are in difficult to describe the curved surface with functions, a convenient and effective method based on secondary exploitation of CATIA for extracting information from shoe last surface is proposed.2) Through using the compute method mentioned in above part to abstract the coordinates and normal vector of positioning and clamping of shoe last, setting up the fixture coordinate system, and then put the data extracted from the shoe last coordinate system into matching the fixture coordinate system.3) According to the result of the shape of shoe last surface and the process requirements analysis, the fixture arrangement of shoe last components is proposed; and in purpose of reducing the process deformation of shoe last workpiece, apply the genetic-algorithm to optimize the fixture arrangement and the clamping-force synchronously. Taking a specific shoe last for example to accomplish the creation design, and the result indicates the maximum deformation is only 0.82 mm, showing a obvious decrease as 0.25 mm smaller than the one in experimental fixture design; and the value of clamping force in option design is 377.8 N lower than the one in experimental design showing a 47 of percentage decrease. 4) Applying self-adapting reconfiguration metamorphic mechanism principles in flexible fixture design, and conduct creation design combining the reconfiguration characteristic of shoe last workpiece with free curved surface; then analyze the freedom and topology structure of shoe last clamp organ which can fit the clamping requirements of different kinds of fixture, then complete mechanism design of flexible fixture for shoe last.5) Based on dynamical and the force analysis result of simulation of flexible fixture for shoe last by using professional analysis software ADAMS, a kind of stable and effective clamp force can be provided to shoe last from shoe last clamp mechanism, that proves the mechanism design's successful.