Study On Forming System Design And The Forming Principles For Wire And Arc Additive Manufacture

The emergence and development of wire and arc additive manufacture(WAAM)provides a new idea for die repair and remanufacturing.This method can achieve automated repair process,improve production efficiency and save a lot of material.But at present,the technology still stays in the stage of basic theoretical research and preliminary experimental exploration,and cannot be applied to the production practice.This paper focuses on the forming system design and the forming principles study for WAAM,with the aim of the successful application of this technology.The forming system for wire and arc additive manufacture was designed,based on the cold metal transition technology(CMT).The system takes KUKA robot and Fronius digital welding machine as the main hardware equipment to achieve a stable,efficient and flexible process of welding.The software system is mainly based on Mastercam and 3D Automate,which can generate robot paths for WAAM by the "reverse milling" method.In addition,the robot program conversion module is developed to control the motion of the robot by off-line programming.Furthermore,the path planning methods of multi-layer single-bead,single-layer multi-bead and multi-layer multi-bead are studied based on Mastercam,and their path generation methods and forming strategies are obtained.For multi-layer single-bead open-path parts and closed-path parts,two sides lifting and inclined lifting are respectively adopted to improve the flatness of the forming parts in the lifting place.For single-layer multi-bead,the weld plane adopting the path generated by unidirectional and bidirectional cutting mode is relatively flat.Through the experiments of WAAM with the metal parts with different materials and structures,the validity of path generation methods and the feasibility of path planning are verified.The reasonable process parameters interval of hot work die steel was obtained by analyzing the forming appearance of the welded metal under different process parameters.And then,the influence of welding parameters on the weld size was studied.The results show that under other constant conditions,the weld width increased and the weld height slightly increased with the increase of welding current;the width and height of welded metal decreased with the increase of welding speed.In addition,the relationship between the process parameters and weld size was established,using a general,rotational,and combinational design of quadratic regress.This model provides the basis for slicing and planning the modeling geometric data of metal parts in the process of WAAM.Rectangular parts,trapezoidal body parts and crankshaft simulated parts were fabricated by WAAM,using flux cored wire for die repairing.The results showed that the overall forming appearance of parts was basically consistent with the design expectation,but the surface quality was bad.The tensile strength,impact toughness,hardness of the forming parts are not less than 90% of the parts fabricated by manual building-up welding,which basically meet the application requirements.This verifies the feasibility of remanufacturing and repair die by WAAM.