Journal of Manufacturing Processes最新文献

Turbine blisk is the core part of an aero-engine, which is characterized by its complex blade profile, resulting in the difficulty of its polishing. In this study, a novel process of chemical-mechanical fluid-solid coupling polishing was proposed to achieve high-quality and high-efficiency polishing for the blisk. Analyzed the principle of chemical-mechanical fluid-solid coupling polishing process of the blisk with the material of K418 nickel-based alloy. Then, established the material removal theoretical model of the process, and investigated the influence law of process parameters on the blisk surface force state to obtain the optimal parameters by using FLUENT fluid simulation. Moreover, simulated the abrasive particle trajectory to reveal the formation mechanism of the blisk surface with high-quality and high-efficiency. Furtherly, experiment shows that the novel process can effectively improve the blisk surface quality, and the surface roughness Ra decreased from 3.151 μm to 0.779 μm. This method provides a novel solution for precision polishing of the complex structural parts.

Investment casting plays a pivotal role in the fabrication of complex and precise components, notably turbine blades for aerospace and energy industries. During the casting process, the non-uniform shell thickness distribution affects the dimensional accuracy and surface quality, and further impact the performance and reliability of the products. This study delves into the effects of turbine blade casting system design, focusing on shell thickness uniformity and its correlation with casting dimensional accuracy. Through an experimental setup that manipulates wax pattern attitude angles and module diameters, coupled with the Industrial Computed Tomography (ICT) for non-destructive thickness measurement, this study uncovers the critical role of centrifugal effects during the slurry application in modulating shell thickness uniformity. Our findings reveal that strategic adjustments to the wax pattern attitude angle and module diameter can significantly enhance shell thickness uniformity, thereby potentially increasing the structural integrity and dimensional precision of turbine blades. In addition, a positive correlation between shell inhomogeneity and casting manufacturing deviation was found through casting profile inspection and correlation analysis. This research not only elucidates the relationship between manufacturing parameters and shell formation but also proposes practical adjustments to the casting system design, offering new pathways to refine investment casting processes for high-value components.

In order to clarify the mechanism of particle size distribution in DLP printing process of HA ceramics, five groups of HA slurries with different particle size distributions were prepared, and the effect of particle size distribution on the performance of HA slurry and printed HA samples was systematically studied. The results demonstrated that increasing the content of nano HA powder enhances the stability of the HA slurry. However, this also led to an increase in excess curing width due to intensified scattering during the curing process. In terms of the performance of the sintered samples, due to the higher sintering activity of nano powder, the increase of nano HA content from 0 % to 40 % promoted the linear shrinkage of the sample size in the x, y, and z directions, and increased the density of the sintered parts by 13.25 %, the compressive strength by 21.36 %, and the flexural strength by 81.14 %.

Laser Direct Energy Deposition (LDED) emerges as a promising technology to repair damaged single crystal (SX) superalloy components with superior properties due to its high efficiency and good precision. However, stray grains (SGs) are still the major challenges that compromise repair quality though multiple techniques have been explored. The current work delves into understanding and mitigating SGs by physically elucidating the Parameter-Process-Structure (PPS) relationships. The Parameter-Process relationship is revealed by discussing the semicircular-to-undulating shape transition (SUT) under various parameter sets, probing the natural tendency of SX superalloy towards SGs through dimensional analysis and modeling the parameter-induced transitions in flow dynamics. The Process-Structure correlation is next derived by researching the oriented-to-misoriented transition (OMT) through transient thermal analysis regarding solidification and predicting the SGs fraction using high-fidelity simulation. The proposed PPS relationships in laser remelting are further confirmed in LDED by physically connecting the correlations between parameter variation-melt pool dynamics-SGs formation. It is revealed the melt pool of SX superalloy naturally shows susceptibilities of undulating shape and its boundary is controlled by thermal advection. The undulation is prone to being formed under higher heat energy input as the enhanced flow instability and the increased flow intensity characterized by the number and the intensity of inside vortex. SGs are sensitive to the undulating melt pool due to the inflection-induced increment in solidification angle and SGs fraction shows a significant increase with energy input. The obtained PPS physics work for both the laser remelting and LDED though the process complexity has been greatly raised by the powder stream and provide insights into the parameter optimization, process adjustment, and quality improvement for the laser repairing of SX superalloy-manufactured parts.

This manuscript presents the development of multi-agent Deep Reinforcement Learning (DRL) for radiation thermal control in thermoforming processes involving multiple heaters. The complexity of such control systems is characterized by significant action and state spaces, where the actions of all actuators collectively influence the system's output. This complexity introduces substantial challenges regarding the computational demands for offline training of learning-based algorithms and the online computational costs associated with a real-world controller deployment. The study presents a novel approach to training an adaptive and robust DRL agent system that can control a single heating element on the thermoplastic sheet while dynamically considering interactive effects from nearby heaters. Results demonstrated that upon deploying the pre-trained agent for each heater within the heater bank, the group of agents could then regulate the temperature of the sheet to any physically feasible output temperature profile. In contrast to the conventional DRL approach, where a single agent manages all heaters, the multi-agent DRL method boasted that an offline training process was 110 times faster, coupled with an 8 times reduction in the final error margin on the simulator. The experimental data, conducted on a laboratory-scale setup, confirmed the performance of the proposed model, with a final absolute error under 4 ${}^{°}C$. Regardless of the number of heaters, the multi-agent DRL approach exhibited accurate and robust performance. Its advantage was that it incurred no significant offline and online computational burden when the number of heating elements increased, deemed a promising notion for industrial-scale applications.

The copper pattern electroplating rate significantly impacts electronic packaging substrate preparation efficiency. The direct current (DC) electroplating technique has great potential in economy and convenience but faces challenges in improving the electroplating rate and coating properties, thus making electroplating additives the most critical parameters for controlling the electroplating process and coating properties. Convection and cathodic polarization are two essential parameters influencing the additives' interactions, but the electrolyte flow field distribution is complicated by the changed pattern size, and most electrolyte formulas cannot withstand such strong cathodic polarization. Therefore, we presented a novel electrolyte formula for ultra-high-rate DC copper pattern electroplating and employed three-dimensional flow field simulation to investigate the flow field distribution throughout the patterns. An ultra-high current density of 8 A/dm² was applied, ensuring a stable electroplating process. The pattern size-stimulated electrolyte flow rate trend was discovered by simulations. The mechanism of simultaneously achieving ultra-high-rate electroplating and coating property improvement was thoroughly investigated. An ultra-high rate of 150 μm/h and the dense, uniform copper pattern coating were achieved synchronously with weak convection and strong cathodic polarization. Utilizing the ultra-high-rate copper electroplating method offers a viable approach to expedite the production of electronic packaging substrate with enhanced efficiency.

As the key properties of copper alloys, achieving high strength and high conductivity are contradictory. Therefore, balancing strength and electrical conductivity is essential in optimizing the properties of copper alloys. This paper presents a detailed investigation into the evolution of multi-scale heterostructures and the properties of CuCrZr-Y₂O₃ composites prepared by additive manufacturing during the annealing process. The multi-scale heterostructures, including grain size and cellular dislocation substructure, demonstrated no significant changes during the annealing process, which occurred from low to high temperatures. Following low-temperature aging treatment of the CuCrZr-Y₂O₃ composites, the formation of fine particles, including the Cr phase, Cu₄Zr phase and YCrO₃ phase particles, was observed. In comparison to the as-built and high-temperature annealed samples, the low-temperature aged samples exhibited the optimal combination of hardness (204 ± 10 HV), electrical conductivity (83.5 ± 0.7 %IACS) and strength (589 ± 10 MPa). The precipitation of solid solution atoms and the formation of the fine particles enhance the Orowan strengthening mechanism and improve the conductivity. This study precisely modifies the multi-scale heterostructures of the CuCrZr-Y₂O₃ composites, offering novel insights into the electrical conductivity behavior and strengthening mechanisms.

The establishment of appropriate acoustic plastic constitutive model is fundamental for the prediction of temperature and strain/strain rate histories which are key process variables determining the weld quality in the ultrasonic vibration assisted friction stir welding (UVaFSW) process of dissimilar Al/Mg alloys. In this study, a double-internal-variable dislocation based constitutive model is proposed to describe thermomechanical behaviors without/with ultrasonic vibration (UV) more suitably. Combined with computational fluid dynamics model, the constitutive equation is applied to simulate the UVaFSW process of dissimilar Al/Mg alloys, and the effects of UV on the heat transfer, strain/strain rate and material flow are quantitatively studied. The results indicate that the ultrasound increases the probability of dislocation annihilation and reduces the immobile dislocation density in the plastic deformation area, leading to a significant decrease in material flow stress. Besides, the calculation results under different heat inputs indicate that a reasonable heat input can maximize the beneficial effects of ultrasound in UVaFSW. Compared with the experimental data, the results simulated by the developed constitutive equation is validated with a high prediction accuracy.

For robotic grinding of blisks, the tool and workpiece easily interfere with each other in the grinding process, which results in severe damage to the tool and workpiece. Therefore, interference-free tool orientation planning is a core issue of robotic grinding. Currently, most interference detection techniques are based on the discretization of geometric elements, but the surface discretization accuracy and computational efficiency conflict with each other, which results in low calculation efficiency to realize acceptable accuracy. In this paper, with the aim of addressing the interference problem in the grinding of complex components, an algorithm is developed for the efficient construction of an interference-free region and tool orientation planning in robotic grinding. First, the critical points on the edge of the checking surface are solved by the quadratic Newton-Raphson method. Then, the special critical point of the edge is taken as the search starting point on the checking surface, and the equal step and variable scale methods are combined to search the remaining critical points. The obtained critical points are sorted to construct the closed interference-free region. To improve the quality of the machining surface and material removal accuracy, the grinding tool orientations are generated with the target of optimal conformity between the tool and machining surface in the interference-free region. Robotic grinding experiments on the blade integrated disk reveal that the developed method can effectively avoid interference in the robotic grinding process, the material removal accuracy of the processed workpiece profile is improved by 44.2 %, and the surface roughness is reduced by 61.1 %.

The resistivity of the interconnection is a crucial restriction to its performance. In this paper, pulsed laser scanning annealing (PLSA) is proposed as a novel annealing method to reduce the resistance of copper interconnects. The impacts of pulsed laser irradiation on copper interconnect resistance are studied in terms of grain growth and impurity diffusion by experiments and simulations. The temperature gradient generated by laser induces the in-plane and in-depth columnar grain growth, with maximum grain sizes of 17.4 μm and 21.6 μm, respectively. The impurity diffusion is stimulated when the single pulse energy exceeds a threshold at the same laser power density, verified by experiments and calculations. The amount of total escaped impurities and Cl is 83.2 % and 89.2 % higher in PLSA than in thermal annealing, respectively. As a result, copper films with conductivity up to 98.6 % international annealed copper standard were obtained, which makes PLSA a potential application for future advanced interconnects.