Filling Path Planning and Polygon Operations for Wire Arc Additive Manufacturing Process

To improve the service life of hot forging die, the additive manufacturing algorithm and additive manufacturing device for die remanufacturing are developed. Firstly, a compound filling algorithm in which the inner zone is filled by linear scanning and the outer contour is filled by offsetting is developed in order to solve the problems encountered in filling path planning for wire arc additive manufacturing (WAAM) like staircase effect at marginal division, degenerated edge at outer contour, programming difficulty, and so forth. Meanwhile, the attitude control algorithm of welding gun is proposed to control the angle between welding gun and welding path so as to improve the welding forming quality. Secondly, the high-temperature and low-temperature wear resistances of Fe-based and Ni-based alloy are tested. The results show that Ni-based alloy has higher high-temperature wear resistance. Finally, a disabled crankshaft hot forging die is selected for application test and the results show that, using the techniques discussed in this paper, welding materials can be saved by more than 50% and machining cost can be saved by more than 60%. In addition, the surface of automatic-repaired die is smooth without oxidation, collapse, and other defects after forging 3000 times, which is much better than that of manual-repaired die.

A Path Generation Method for Wire and Arc Additive Remanufacturing of Complex Hot-forging Dies

Wire and arc additive remanufacturing (WAAR) technology has become a new solution for hot-forging dies repair and remanufacturing. In this study, a path generation method is proposed for WAAR of hot-forging dies. At first, a WAAR process of the hot-forging die is presented, and considering the characteristics of large welding heat input and complex 3D digital model, the hybrid path planning strategy is confirmed as an appropriate strategy for WAAR. The developed hybrid path generation method for WAAR consists of three main steps: determinate the direction of the scan line; divide and fill the internal area; and connect the sub-paths. the relatively optimal scanning direction is determined by calculating the length and inclination angle of each line segment in the contour lines, which reduces the possibility of sharp angles. The internal region is divided based on the location of the selected extreme points, and the path space is adjusted to avoid the occurrence of the underfilled phenomenon. At the stage of sub-paths connection, some criteria are proposed to reduce the number of sub-paths. At last, a planar deposition experiment and the WAAR process of four damaged hot-forging dies are carried out to validate the effectiveness and robustness of the proposed method.

Research on Gradient Additive Remanufacturing of Ultra-large Hot Forging Die Based on Automatic Wire Arc Additive Manufacturing Technology

In this paper, an automatic WAAM technology are proposed to realize the gradient additive remanufacturing of ultra-large hot forging dies. Firstly, a vertical additive manufacturing strategy and a normal additive manufacturing strategy are proposed to meet different additive manufacturing demands. Secondly, the basic principle of layering design of ultra-large hot forging dies is developed, and the wear resistance of Ni-based, Co-based and Fe-based alloys at room temperature and high temperature is analyzed. The Co-based alloy has the best high temperature wear resistance, which can be used on the surface of the hot forging die to strengthen the die. In order to control the forming quality of additive manufacturing, the relationship between welding parameters and weld shape was discussed, and the reverse system of welding process parameters was built. Finally, a typical aviation ultra-large hot forging die is selected as the research object. According to different stress and temperature distribution in different regions of the ultra-large hot forging die in service, materials with different properties are used in corresponding regions to improve the service life of the die, reduce the remanufacturing costs and improve the remanufacturing efficiency. The experimental results show that the service life of the hot forging die repaired by the automatic gradient function WAAM technology is significantly increased, the material is reduced by more than 50% and the production efficiency is increased by more than 50%.