Comprehensive analysis of arc additive manufacturing technology

Additive manufacturing (Additive Manufacturing, AM) technology is based on the discrete - accumulation principle, the part driven by the three-dimensional data, a method of rapid prototyping material layer by layer the accumulated technology manufacturing solid parts. The biggest advantage of this forming method is that it can form, reduce the process and shorten the product manufacturing cycle without the need of traditional tools. It is especially suitable for the manufacture of low-cost and small-volume products, and the more complex and high value-added products, the rapid and efficient forming. The more significant the advantages, the broad application prospects in the fields of aerospace, biomedicine, energy and chemical, micro-nano manufacturing.

Faced with the requirements of low cost and high reliability of new aircraft, its components are gradually becoming larger and more integrated. Additive manufacturing technology eliminates the need for molds, and can directly manufacture complex components at low cost. It is expected to further optimize the structure of existing aircraft components, improve structural efficiency, and achieve lightweight and high structure based on the advantages of additive manufacturing technology in configuration capabilities. Performance. Due to the simplification or omission of process preparation and mold design in traditional manufacturing, the product digital design, manufacturing and analysis are highly integrated, which can significantly shorten the development cycle and R&D costs.

Metal additive manufacturing techniques can be divided into three categories according to the type of heat source: laser, electron beam and arc. In the past 20 years, we have mainly studied the powder-based metal additive manufacturing technology using laser and electron beam as heat sources. By continuously melting or sintering metal powder, we continuously prepare complex structural parts layer by layer. Now it has been applied to aerospace, defense military, energy power. Some key components in the field of high-precision technology, but due to its raw materials and heat source characteristics, metal powder-based laser and electron beam additive manufacturing technologies are limited in forming certain structures or components of specific components and cannot be realized or even Forming, its raw materials, time cost is high, has many shortcomings: (1) for laser heat source, its forming rate is slow, aluminum alloy has low absorption rate of laser; (2) for electron beam heat source, vacuum furnace size Limitation on the volume of the components; (3) The high cost of preparation of the powder-based metal raw materials, the vulnerability to contamination, and the low utilization rate all increase the cost of raw materials.

Based on the above reasons, the existing technology shows certain limitations when forming large-sized and complex structural parts. In order to cope with the demand for additive manufacturing of large-scale and integrated aerospace structural parts, the low-cost and high-efficiency developed based on surfacing technology Arc additive manufacturing technology has attracted the attention of some scholars. Wire and Arc Additive Manufacture (WAAM) uses arc as the energy beam to manufacture metal solid components by layer-by-layer surfacing. This technology is mainly based on TIG, MIG, SAW and other welding technologies. It consists of all welded joints with uniform chemical composition and high density. The open forming environment has no limitation on the size of the formed parts. The forming rate can reach several kg/h, but the surface of the parts manufactured by arc additive is fluctuating greatly, and the surface quality of the formed parts is high. Lower, generally requires secondary surface machining. Compared to laser and electron beam additive manufacturing, the main application target of arc additive manufacturing technology is low cost, high efficiency and fast near net shape forming of large and complex components.

This paper mainly introduces the current status of arc additive manufacturing technology, analyzes the shortcomings of this technology research at this stage, discusses its possible development direction, and expounds the application of this technology in large-scale and integrated high-end aerospace parts manufacturing.

WAAM technology status

1WAAM equipment system: 1.1 basic hardware components and characteristics

Arc additive manufacturing is a digital continuous overlay welding process, and its basic forming hardware system should include a forming heat source, a wire feeding system, and a motion actuator. The manufacture of three-dimensional solid parts by arc additive depends on the repeated reproduction of the molten pool on-line, surface and body by point-by-point control. If the characteristics of the energy-carrying beam are considered, the more stable the arc is, the more favorable the forming process control is, that is, the continuous shape forming. consistency. Therefore, arc-stabilized, spatter-free non-molten gas shielded welding (TIG) and Cold Metal Transfer (CMT) technology based on melt inert/active gas shielded welding (MIG/MAG) have become the main use at present. The way the heat source is provided.