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EN
Additive manufacturing (AM) is used in metal part forming for its innovative character but its potential for sustainability is uncertain. The energy and material consumption required for manufacturing are significant. Thus, the research question of this article is: "What are the current uses of AM that present a real potential for reducing environmental impact?". The WAAM (Wire Arc Additive Manufacturing) process appears to be the most energy-efficient in comparison to other AM processes. A process parameters study shows that deposition rate has a substantial impact on energy consumption. This parameter represents the amount of material deposited in a unit of time and is directly linked to productivity. It appears that an increase of the deposition rate leads to a reduction in energy consumption. Experiments on WAAM with a high deposition rate permits to create a database of energy and material consumption. This database is then used to identify cases of parts made with WAAM that offer a significant impact reduction compared with conventional manufacturing processes.
EN
The current practice of reconstruction of oxidized turbine parts (due to hot corrosion) using arc welding methods facilitates restoration of the nominal shapes and dimensions, as well as other attributes and features. Intense development of 3D additive methods and techniques contributes to the repair/modification of different parts including gas turbine (GT) hardware. The article proves the viability of the concept of using a robotized additive arc welding metal active gas (MAG) process to repair and modify gas turbine diaphragms using different filler materials from the substrate. The industrialized robotic additive process (hybrid repair) shows that very good results were achieved if the diaphragm is cast of nickel-iron and the filler material for welding the passes is austenitic stainless steel (for instance 308 LSi). This is one of the novelties introduced to the repair process that was granted a patent (US11148235B2) and is already implemented in General Electric Service Centers.
EN
The article presents an analysis concerning the obtainment of weld deposit properties (declared by the manufacturer of the filler metal) in the finished products made using additive manufacturing processes involving the application of arc welding methods. The use of an incompatible base material during the initial stage of the additive manufacturing process led to significanchanges in the chemical composition of the obtained layer (when compared with the chemical composition of the weld deposit declared by the producer of the filler metal). The dilution of the partly melted incompatible base material with the weld deposit resulted in the obtainment of a layer characterised by different properties (i.e. microstructure, hardness, corrosion resistance) than those declared by the manufacturer of the filler metal. The results obtained in the tests described in the article were compared with the requirements related to the making of the weld deposit subsequently subjected to the analysis of chemical composition (in accordance with the PN-EN ISO 6847 standard). The requirements specified in the aforesaid standard are used during tests related to, among other things, the conformity assessment procedure applied when qualifying filler metals.
PL
W artykule przedstawiono analizę problemu związanego z otrzymywaniem, deklarowanych przez producenta materiału dodatkowego, cech stopiwa w gotowych wyrobach kształtowanych przyrostowo z użyciem łukowych metod spawalniczych. Zastosowanie niedopasowanego materiału podstawowego do kształtowanego przyrostowo wyrobu na początkowym etapie wytwarzania prowadzi do istotnych zmian składu chemicznego pomiędzy uzyskaną warstwą a deklarowanym składem chemicznym stopiwa. Na skutek wymieszania nadtopionego niedopasowanego materiału podstawowego ze stopiwem uzyskiwana jest warstwa, która charakteryzuje się innymi cechami (tj. mikrostruktura, twardość, odporność na korozję) niż deklarowane przez producenta spoiwa. Wyniki te odniesiono do wymagań dotyczących wykonania stopiwa do analizy składu chemicznego, zgodnie z PN-EN ISO 6847, stosowanych do badania stopiwa, m.in. w ramach procedury oceny zgodności podczas kwalifikowania typu materiału dodatkowego do spawania.
EN
The Wire Arc Additive Manufacturing process (WAAM) is designed for the manufacture of large metallic parts with no joints, very little waste material and hardly any support. It is gaining its space inside the naval, aeronautics and space industries. However, there are key challenges to be solved in order to increase the performance of the WAAM process. Parts with curved shapes are difficult to manufacture with regular parallel layers without support because of an excessive overhang in certain regions. This paper proposes a methodology that solves this issue, by using incrementally angled layers with variable bead height, which eliminates or decreases the overhang between layers. This solution uses an angled rotary positioner (or other method for moving the part in a controlled way) and controls key parameters like the travel speed, the deposition angle, the available bead height difference, etc. The efficiency of the developed proposal is shown with the manufacture of a large curved steel (316L) piece as a use-case.
EN
This fundamental research deals with the investigation of material property model influences on distortion induced by multi-layered Wire Arc Additive Manufacturing (WAAM) with synergic-pulsed gas metal arc welding (P-GMAW) process which was modelled and simulated by means of non-linear numerical computation. The material property models of stainless steel SS316L component to be compared stem from three different sources namely existing database, initial wire and evolved component. The new property models were generated with advanced material modelling software JMATPRO based on chemical compositions analysed at initial wire and component using SEM–EDX. The flow curve for each material model was taken with the strain rates ranging from 0.001 to 1.0 s−1. In the numerical simulation, a coupled thermomechanical solution was adopted including phase-change phenomena defined in latent heat. Goldak’s double ellipsoid was applied as heat source model and simplified rectangular bead with hexagonal element type and meshing was developed to avoid extensive pre-processing effort and to reduce the computational time at post-processing level. Temperature behaviour due to the successive layer deposition was simulated considering heat transfer effect coupled to mechanical analysis. The adjustment of simulative transient to experimental thermal distribution lead to new fitted heat transfer coefficient. Prior to execution of numerical simulation, a sensitivity analysis was conducted to find the optimal number of elements or mesh size towards maximum reached temperature. It can be concluded based on the adjusted model, selected mesh size and experimental validation that numerical computation of substrate distortion with evolved material property of component and initial wire of SS316L yield closer average result within the relative error ranging between 11 and 16% compared to database material giving more than 22%.
EN
Three-axis machines are limited in the production of geometrical features in powder-bed additive manufacturing processes. In case of overhangs, support material has to be added due to the nature of the process, which causes some disadvantages. Robot-based wire-arc additive manufacturing (WAAM) is able to fabricate overhangs without adding support material. Hence, build time, waste of material, and post-processing might be reduced considerably. In order to make full use of multi-axis advantages, slicing strategies are needed. To this end, the CAD (computer-aided design) model of the part to be built is first partitioned into sub-parts, and for each sub-part, an individual build direction is identified. Path planning for these sub-parts by slicing then enables to produce the parts. This study presents a heuristic method to deal with the decomposition of CAD models and build direction identification for sub-entities. The geometric data of two adjacent slices are analyzed to construct centroidal axes. These centroidal axes are used to navigate the slicing and building processes. A case study and experiments are presented to exemplify the algorithm.
EN
Additive Manufacturing (AM) for metal part can be divided into two different types: The powder technology and the wire technology. Usually, powder is adapted for fine components and small parts whereas wire is used for structural components and large scale part. One of the main benefits of AM is to simplify assemblies by reducing the number of components and to provide a large freedom of design. A standard AM system consists of a combination of three blocks: a motion system, a heat source and a feedstock. For Wire Arc Additive Manufacturing (WAAM), the heat source is a welding generator and the feedstock is a wire. The motion system generally used is a 6 axis robot or a CNC machine. This paper aims to propose a methodology to generate 5 axis toolpaths for WAAM and highlight the main parameters which selection is a key issue to resolve. The goal is to compare 3 axis and 5 axis toolpaths on part accuracy, depending the clearance angle of the part.
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