Work Envelope Expansion and Parametric Optimization in WAAM with Relative Density and Surface Aspect as Quality Constraints: The Case of Al5Mg Thin Walls with Active Cooling

The successful and efficient production of parts with specific features by Wire + Arc Additive Manufacturing (WAAM) strongly depends on the selection of proper and typically interrelated deposition parameters. This task might be particularly challenging in the making of thin walls, which might be highly impacted by processing conditions and heat accumulation. In this context, this study aims at expanding the work envelope and optimizing the parametric conditions in WAAM with relative density and surface aspects of the preforms as quality constraints. The experimental approach was based on the deposition of thin Al5Mg walls by the CMT process on its standard welding setup and with an active cooling technique to enhance the deposition robustness. Internal voids were estimated by Archimedes’ method. The surface quality of the walls was assessed through the visual aspect and the surface waviness by cross-section analysis. All the conditions presented relative density higher than 98%. The upgrade of the standard welding hardware to WAAM purposes through the addition of a supplementary shielding gas nozzle to the torch and the intensity of the heat sinking from the part significantly expanded the process work envelope, with its applicability being successfully demonstrated with multi-objective optimization. To sum up, a decision-making procedure is presented towards achieving intended preform quality.

Optimization Method of Location for Cooperative Lifting of Two Mobile Cranes

Dual-crane lifting has been generally used with the need of erection and installation of large equipment. Choosing proper locations for two mobile cranes is an important work as well as a difficulty in design of heavy lifting plan. So, this paper proposes an optimization method of location for cooperative lifting of dual-crane. This approach starts with determining search field and maximum step length, and then finds out load’s possible initial locations by bisection method; secondly calculates work envelope of dual-crane which will be dispersed to find all dual-crane’s possible locations; after this, it puts cranes in their respective possible locations corresponding to each load’s location and simulates the whole lifting course while carries out collision detection to exclude crash happened locations; finally, creates weighted optimization function, uses enumeration method to traverse all collision-free locations, and gains optimal location of dual-crane and load. At last, this approach has been used in an actual engineering case and optimal location is got, from which we can see its feasibility and validity.

Kinematics Simulation and Design of Work Elements of Demolition Robot Based on Virtual Prototype

Work Scope is key performance to the Demolition robot and is also a major factor consider to the users. CATIA and ADAMS were employed to design the 3D model and do the kinematics simulation to complete the design of work element of Demolition Robot. Parameters of assembly and interference detection of the 3D model was checked in the CATIA before taking the kinematics simulation experiment. The simulated result indicated that maximum radius, maximum depth and maximum height of Demolition Robot could be obtained, variance of forces at key articulated points and scope of work envelope diagram were presented, which provides a new method to analyze and design Demolition Robot.