In large-area hybrid electrical discharge–electrochemical machining (EDM–ECM) sinking machining, discharge debris, electrochemical products and gas bubbles are difficult to evacuate from the narrow and relatively enclosed gap, leading to particle retention, unstable discharge and reduced dimensional accuracy. This study proposes a suction-assisted convergent flow-field strategy using a multi-hole electrode. Flow-field and particle-transport simulations, discharge waveform analysis and machining experiments were conducted to examine the effects of electrode-hole configuration and liquid-supply mode on debris evacuation, discharge stability, dimensional accuracy and surface integrity. Among the tested electrode configurations, the four-hole configuration provided a favorable balance between average gap velocity and velocity-distribution uniformity under the present electrode geometry. At 0.30 MPa, internal suction increased the average gap velocity from 4.4 to 5.6 m/s and reduced the particle evacuation time from 0.0048 to 0.0032 s. It also increased the normal discharge ratio from 52.10% to 65.68% and reduced the abnormal discharge ratio from 17.92% to 12.44%. Compared with internal flushing, internal suction reduced the relative electrode wear ratio from 3.7% to 2.2%, Ra from 0.52 to 0.31 μm, and the cavity diameter deviation from 1.70% to 0.73%. An approximately 10.22 μm-thick recast layer was observed under internal flushing, whereas no obvious continuous recast layer was detected under internal suction; meanwhile, the sidewall angle decreased from 112.6° to 97.4°. These improvements are attributed to faster particle evacuation and improved inter-pulse dielectric recovery under the convergent suction flow.
In the field of aeronautical manufacturing engineering, traditional manual positioning methods for mounting equipment on aircraft wings suffer from issues such as low operational efficiency and insufficient alignment accuracy, which have become bottlenecks affecting the rhythm of final assembly lines. To address these challenges, this paper develops a real-time visual perception and 3D guidance system based on ArUco markers. This system uses monocular vision to achieve full-process automation in an integrated development environment, including marker generation, camera calibration, and real-time 6-degree-of-freedom (6-DoF) pose calculation. By integrating real-time pose data with a 3D visualization engine, a 3D visualization system is developed, which maps virtual models to physical entities in real time to clearly display deviation information and provide spatial operation guidance. The experimental section systematically evaluates the positioning accuracy, real-time performance, and mounting time of single-marker and multi-marker systems at various typical parameter configurations. Results show that the system achieves sub-millimeter position accuracy and sub-degree angle accuracy under laboratory conditions relative to the selected reference methods within most typical parameter configurations, with system processing latency below 20 ms. The developed visualization system improves operational efficiency as measured by task completion time, and received positive subjective feedback from participants in post-experiment questionnaires. This study offers a low-cost, easy-to-deploy visual guidance system for aircraft wing equipment mounting operations, with quantified performance bounds under laboratory conditions, providing a foundation for future field validation.
To address flow instabilities and defects such as trailing and stringing in the piezoelectric jetting of high-viscosity adhesives, this paper proposes an arc-shaped self-excited oscillating microchannel structure. Based on an integrated “nozzle–oscillation chamber–feedback channel” configuration, numerical simulations and experiments reveal the self-excited oscillation mechanism: flow instability within the chamber couples with pressure feedback, forming a periodic “acceleration–stretching–retraction” cycle that significantly improves the consistency and stability of high-viscosity droplet detachment. The non-monotonic influence of key geometric parameters of the oscillation chamber and nozzle was systematically analyzed, and the optimal parameter range for effective coupling between velocity pulses and dynamic pressure pulses was identified. A complete set of structural parameters of a novel arc-shaped self-excited oscillating microchannel was ultimately determined. The microchannels fabricated under these parameters can produce adhesive droplets with a minimum single-dot volume of 0.53 nL and a single-dot diameter of 0.148 mm under the current experimental conditions. Experimental results demonstrate that the optimized microchannel generates a stable oscillating jet, with droplet ejection patterns highly consistent with simulation results. This validates the effectiveness of the structural design and provides a reliable solution for high-precision packaging.
The distribution state of machining allowance provides the basis for process-parameter formulation and machining-accuracy control, and it has an important influence on the final machining quality of blades. However, existing machining-allowance allocation methods primarily aim to improve machining efficiency by minimizing the overall machining allowance. This emphasis may cause substantial spatial fluctuations in the allowance distribution, which can result in local material shortage or excessive stock in thin-walled blades with complex geometries. As a result, machining quality and stability are reduced, while higher requirements are imposed on the dynamic performance of the machining system. To address these problems, this paper proposes a Modified MOEA/D-based method for uniform machining allowance allocation of aero-engine blades, with machining efficiency and stability requirements considered simultaneously. First, according to the practical machining requirements of blades, an allowance allocation optimization model is established, aiming to minimize the overall allowance level and improve allowance uniformity under the non-negative allowance constraint. Then, a machining allowance calculation strategy based on curvature-based partitioning is proposed to reduce allowance calculation errors in high-curvature regions of the blade, thereby providing accurate data input for allowance allocation. Finally, a modified MOEA/D-based multi-objective optimization method is developed by incorporating a stepwise optimization strategy, a differential evolution operator and an adaptive penalty function. The results of the comparative experiments demonstrate that the proposed method improves the uniformity of blade machining allowance distribution while satisfying the nonnegative allowance constraint, and achieves faster convergence, which helps improve the stability and quality consistency of blade machining.
Capillary drilling (CD) represents a crucial technology for the efficient production of small-hole arrays with excellent surface integrity in difficult-to-cut metals. The wire recession deviation introduced during the assembly of “capillary-wire” electrodes often deteriorates the machining consistency; however, its impact has yet to be clearly understood. This study measured the wire recession deviation arising from electrode assembly and analyzed its statistical distribution. Subsequently, the effects of the target wire recession and recession deviation on the hole diameter consistency were investigated through theoretical analysis, finite element simulations, and machining experiments. The measurements reveal that the fluctuation range of the recession deviations expands as the target wire recession increases. Statistically, the probabilities of deviations exceeding ±50 μm and ±150 μm are 57.2% and 10.8%, respectively. Theoretical analysis and simulations indicate that increasing the target wire recession not only “dilutes” the relative impact of recession deviation fluctuations by enlarging the inter-electrode gap resistance, but also enhances the homogenization of the current density distribution within the capillary. These mechanisms effectively suppress the effect of recession deviations on the anodic current density distribution, thereby improving the diameter consistency. Utilizing a multi-electrode tool with an optimized target wire recession of 1.5 mm, a 5×5 hole array was successfully machined with high consistency, yielding an average diameter of 664 μm and a diameter variation range of only 19 μm. These findings provide insights into the role of wire recession in the CD process and offer technical support for machining high-consistency hole arrays.
