Research On Three-dimensional Printing Technology For Thermally Driven Flexible Hingle

Flexure hinge is a kind of special motion pair with large deformation and no gap,which can produce complex motion such as bending and torsion by using the deformation of material.3D printing technology is a kind of part model data based,through the printer rapid prototyping technology,is widely used in modern manufacturing industry.It is widely used in modern manufacturing industry.In its 30 years of development,3D printing has spawned more than a dozen molding processes.Among them,fused deposition molding(FDM)is the most suitable and simple one.Due to the increasing complexity of flexure hinge structure,3D printing technology can form the structure which is difficult to manufacture by traditional processing technology.How to apply the melt deposition technology to the manufacturing process of flexure hinge has become an important research direction.In this paper,the flexure hinge and 3D printing technology are combined to produce a new flexure hinge that can achieve bending by thermal drive.The following three parts are studied.(1)According to the thermal expansion effect,a flexure hinge structure was designed,in which polydimethylsiloxane film(PDMS)or thermoplastic polyurethane wire(TPU)with high thermal expansion coefficient was used as active layer,polyimide film(PI)with low thermal expansion coefficient was used as passive layer,and Cr20Ni80 nickel chromium alloy high temperature resistance wire was used as heating layer.FDM three-dimensional printing device was used to adjust different nozzle temperature,printing speed and layer thickness to prepare several groups of TPU.The effects of these three groups of parameters on the dimensional accuracy and density of TPU were studied.By adjusting the printing Angle and arranging the holes in different shape positions on the molding part,the effect of the holes on the elastic coefficient was studied.The experimental results show that with the increase of nozzle temperature,the thickness of the delamination decreases,the dimensional accuracy of the TPU increases,and the density decreases.Both dimensional accuracy and density increased first and then decreased with the increase of printing speed.When the printing Angle is from-45° to 45°,the elastic coefficient decreases,and the elastic coefficients of different hole arrays are also different.(2)The effects of length,width and thickness of PDMS/PI and TPU/PI flexure hinges with different materials,sizes,shapes and different driving voltages on flexure performance were studied.The effects of different printing angles and hole arrays on the bending properties of TPU were studied by arranging round holes and square holes on TPU.The experimental results show that the flexural deflection of the flexure hinge increases with the increase of thermal expansion coefficient difference,the length of the flexure hinge increases,and the width and thickness of the flexure hinge increase first and then decrease.When the ratio of the length to the width of the hinge is 3:1,the flexural deflection of the flexure hinge is maximum.When the applied voltage increases,the flexural deflection and response speed of the flexure hinge also increase.When the printing angle is-45 ° and the hole is square,the bending performance is the best.(3)This paper applies the flexure hinge to flexible mechanical claw,Sshaped bending,annular lifting platform and thermal-driven roller.The mechanical claw is made of four PDMS/PI flexure hinges with a maximum driving force of 2MN,grasping an object with a maximum size of 20×20×25m~3 and a maximum weight of 1.49 g,which is about 2.2 times its own weight.The S-shape bending is formed by two flexure hinges and three PLA strips.When heated,the two flexure hinges bend in different directions to form S-shape.The annular lifting platform consists of four identical fan-shaped flexure hinges that bend upward when heated to propel the platform higher.The structure of heatdriven roller consists of seven flexure hinges connected end to end.When heated,the flexure hinges in the heated section bend and pull the whole ring to roll.Using 3D printing technology to manufacture thermal driven flexure hinges,the combination of new manufacturing technology and new flexure hinges has a certain research prospect,which provides a technical basis for the application of medical instruments,biomimetic equipment and other fields.