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In this paper, a study was conducted on the electrochemical machining (ECM) of titanium-shaped grid holes. Firstly, the polarization characteristic curves of titanium alloy TC4 in different electrolytes were measured by an electrochemical workstation, and the mechanism of action was analyzed. The electrolyte formula was developed for 11%NaCl + 5%NaNO3 saturated ethylenediaminetetraacetic acid (EDTA). Secondly, the equal clearance method was used to design the cathode, gap flow field simulation was used to analyze five different structures of through-liquid slots, and the structural form and size of the through-liquid slots were preferred. The voltage range of ECM was determined to be 14 ~ 22 V by the multi-physical field coupling simulation analysis. Finally, through the process test, the Taguchi algorithm and gray correlation degree method were used to optimize the process objectives; to obtain the degree of influence of different factors on the experimental process objectives, machining voltage > feed velocity > duty ratio > inlet pressure; and to obtain the optimal combination of machining parameters, machining voltage of 20 V, duty ratio of 35%, inlet pressure of 0.7 MPa, and feed velocity of 0.55 mm/min. The titanium-shaped grid holes machined by the optimal process parameters have a dimension error of 0.14 mm and a surface roughness of 0.812 μm, which meet the actual production requirements. Using this process parameter for ECM of the more difficult shaped blind holes (hole depth of 10 mm), the dimension error and roughness meet the processing requirements, which further verifies the feasibility of the optimal parameters. The research results show the ECM can realize high-efficiency and high-quality processing of the titanium-shaped grid hole. It also provides process technology reference for the machining of other complex-shaped hole parts to promote the technical progress of the industry. [ABSTRACT FROM AUTHOR]

Screw drill is one of the most widely used power drilling tools in the field of deep sea drilling because of its excellent performance such as low drilling speed, high torque, and strong overload capacity. However, it has the problems of complex internal structure and long processing stroke of screw drill stator. In this paper, the electrochemical machining (ECM) technology is used to solve the problem of internal spiral curved surface special-shaped deep hole machining. Firstly, the initial cathode structure with spirally increasing tooth surface of six machining teeth is designed, and the gas-liquid two-phase flow field model of the gap is established to simulate and analyze it. The simulation results show that the flow field distribution of the electrolyte in the machining gap is not uniform and the bubble concentration is high. Secondly, the initial cathode structure is optimized by adding different numbers of liquid-increasing grooves on the tooth surface of the machined tooth, and the gas-liquid two-phase flow field is simulated. The simulation results show that the cathode structure with four additional baths on each tooth surface results in a better overall flow of electrolyte in the machining gap, a flow rate of more than 3 m/s in the machining area, and a significant reduction in the concentration of electrolyte bubbles, with a reduced rate of 18.7% and a smaller distribution area for the highest bubble concentration, ensure the machining accuracy. Finally, the orthogonal experiment of 4 factors and 4 levels was designed, and the optimized processing parameters were obtained by gray correlation analysis method, that is, inlet pressure of 0.4 MPa, machining voltage of 11 V, duty cycle of 40%, and cathode feed rate of 0.9 mm/min, under which the deviation of the large end diameter of the deep special-shaped hole was 0.15 mm, the surface roughness of the inner wall of the hole was 0.487 μm. The data shows that this combination of processing parameters meets the production requirements of the product. The data shows that this combination of machining parameters meets the production requirements of the product. The COMSOL simulation method significantly shortens the research cycle and saves research costs. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) is adopted to solve the problem of machining special-shaped deep holes (SSDH) with a large depth-to-diameter ratio. Firstly, the cathode for ECM of SSDH was initially designed by analyzing the structural characteristics of the SSDH workpieces. Secondly, the gap flow field model was established, and the flow field simulation analysis was carried out with COMSOL for different machining gaps, the replenishment structures, and liquid-injected hole angles. The results indicate that when adopting the optimization scheme with a machining gap of 0.3 mm, the replenishment structure with a liquid-increasing hole and a 3° liquid-increasing slot, and a liquid-injected hole angle of 15° in the cathode structure, the flow characteristic of electrolyte in the machining gap has good uniformity, stable flow field, and no turbulence. This scheme solves the problem of low electrolyte velocity near the liquid-injected holes and uneven flow field at the liquid-increasing hole slots and achieves cathode structure optimization. Finally, the optimized cathode was used in the process test of ECM, and the results showed that the optimized cathode solved the problems of workpiece closing and hole wall flowlines, and the surface of the machined hole wall was flat and free of burrs; the dimensional accuracy met the production requirements of the workpieces. The simulation greatly improves the machining efficiency and quality of SSDH, which provides process technical reference for the machining of complex SSDH in mining, petroleum, natural gas equipment, and other fields. [ABSTRACT FROM AUTHOR]

In order to solve the problem of complicated electrochemical machining and unpredictable moulding morphology of shaped hot forging model cavities, this paper takes the "T" shaped cavity made of 40CrNiMoV as the research object. Firstly, the electrolyte formulation development test was carried out for 40CrNiMoV material, and the most suitable electrolyte formulation was selected as 8%NaCl + 11%NaNO3 composite electrolyte through the measurement and analysis of the polarisation characteristic curve. Secondly, a multi-physical field coupling simulation model of electric field, gas–liquid two-phase flow field, temperature field and structural field is established, and based on the COMSOL software, the flow rate, temperature and bubble rate of electrolyte under different process parameters affect the law of anode surface forming accuracy, and the simulation results show that when the inlet pressure is low, the gap electrolyte flow rate of less than 5 m/s is larger, and it is easy to produce the phenomenon of passivation, which will lead to the temperature and bubble cannot be discharged in time, making the forming accuracy lower; in the electrolytic processing of the cavity bubble rate compared to the temperature has a greater impact on the conductivity, accompanied by the voltage increases, more heat and bubbles are generated in the processing gap, making the cavity forming accuracy worse; higher cathode feed rate can effectively improve the taper of the cavity side wall, so the cathode side wall insulation can avoid excessive corrosion of the non-processing surfaces, and the processing accuracy is significantly improved compared to the uninsulated. Therefore, insulating the cathode side wall can avoid excessive corrosion on the non-machining surface and improve the machining accuracy significantly. Finally, validation tests were carried out to obtain the measured values of the non-planar "T" shaped cavity inner wall profile and to compare the theoretical values of the simulation. The results show that the theoretical values of the coupled multi-physical field simulation are close to the measured values and can simulate the actual electrolytic process more accurately, providing a technological reference for the electrolytic machining of complex-shaped cavities. [ABSTRACT FROM AUTHOR]

To improve the pitting problem of titanium alloy cascade electrochemical machining (ECM) and improve the processing accuracy, this paper starts with the development of electrolyte formulation and cathode structure design. Firstly, experiments on the electrochemical properties of titanium alloys and experiments on the improvement of electrolyte formulations were carried out. The experimental results show that the machining accuracy and surface quality of the machining were significantly improved by using a composite electrolyte mixed with 10% NaCl and saturated EDTA-2Na, and the pitting phenomenon on the blade surface was significantly controlled. Secondly, the blade full profile trepanning cathode is designed, the flow field model of the gap between the cascade ECM was established, and the cathode system of the cascade ECM was optimised by flow field simulation analysis using Fluent software, and the cathode structure of the liquid feed on two sides was determined. Finally, experimental verification was completed and the coordinates of the machined workpiece solids and outer wall contours before and after optimisation were compared and analysed. The experimental results show that the use of the optimised electrolyte and cathode structure can effectively improve the pitting phenomenon, significantly improve the machining accuracy and surface quality, and meet the actual production requirements, providing a technical reference for the wide application of ECM technology for titanium alloy materials in the manufacture of aerospace liquid power systems. [ABSTRACT FROM AUTHOR]

Electrochemical machining has the characteristics of no loss of processing cathode, high processing efficiency and good accuracy, and can process complex deep special-shaped holes at one time with simple feed motion. This paper uses electrochemical machining technology to solve the problem of complex deep special-shaped holes that are difficult to machine and designs a three-sided feed-type cathode. Firstly, the gap electric field was simulated and analyzed using COMSOL simulation software. The simulation results show that the width of the insulating layer on both sides of the end and wall of the cathode key tooth slot tip is 0.5 mm, and the rounded angle formed by the deep special-shaped hole key tooth tip is reduced to 0.11 mm after machining. Secondly, a simulation analysis of the gap electrolyte flow field and temperature field was carried out. The simulation results show that the gap electrolyte flow velocity is higher and the flow uniformity is better for the cathode structure with 10 through-holes, and the temperature of the gap electrolyte can be controlled below 30°C, which significantly improves the forming accuracy of the deep special-shaped hole. Finally, process tests were carried out and the best combination of process parameters was obtained by the S/N ratio and grey correlation method. The simulation effectively shortens the cathode development cycle and optimizes the cathode structure. [ABSTRACT FROM AUTHOR]

This paper adopts electrochemical machining (ECM) to machine spiral-shaped deep holes, which are difficult to machine by conventional machining methods. Firstly, a cathode structure with two working teeth with increasing spiral end face dimensions was designed. The interstitial flow field and interstitial bubble field were modelled, and simulations were carried out using COMSOL simulation software to realise the optimisation of the cathode working teeth structure. The results show that the cathode structure with four incremental baths provides good uniformity of gap electrolyte flow, and the flow rate is significantly increased, reaching over 6 m/s. The concentration of bubbles in the interstitial electrolyte is significantly reduced, with a reduced rate of 47% and a smaller bubble distribution area. Processing accuracy and surface quality are effectively improved. Secondly, ECM experiments were carried out. The experimental results were analysed using the response surface method for multi-objective optimisation. The optimised process parameters were obtained as follows: inlet pressure 0.7 MPa, machining voltage 10 V and feed rate 0.9 mm/min. Finally, a qualified sample was machined using the optimised process parameters. The dimensional deviation is 0.28 mm and the roughness is 1.398 μm, which meets the product requirements. This simulation and optimisation method effectively shortens the cathode development cycle and reduces production costs. [ABSTRACT FROM AUTHOR]

Two updated methods based on the Simpson formula, i.e., the updated Simpson-based method (USBM) and the updated Adams-Simpson-based method (UASM), are presented for milling stability analysis. Firstly, the delay differential equation (DDE) is employed to describe the milling process mathematically. Then, the tooth passing period is divided into two subintervals, i.e., the free and forced vibration intervals. Only the forced vibration interval is divided into many equal small-time intervals. Subsequently, the DDE in the state space is solved based on direct integration. By combining the two-step Simpson formula and the semi-discretization method, the state transition matrix of the milling system is constructed using the USBM and UASM. The comparisons of convergence rates are conducted to validate the accuracy of the proposed method. The results show that the proposed USBM and UASM converge faster than the benchmark methods. The stability lobe diagrams and the arithmetic mean of relative error (AMRE) for the one degree of freedom (one-DOF) and two degrees of freedom (two-DOF) milling systems are also obtained by different methods for further accuracy evaluation. Meanwhile, the computational time analysis is also carried out. It is revealed that the proposed USBM and UASM are accurate and efficient methods for milling stability analysis. Besides, the proposed methods can accurately and efficiently predict the stability of milling with both large and low radial immersion conditions. Finally, the effectiveness of the proposed methods is verified by experiments. [ABSTRACT FROM AUTHOR]

Electrochemical machining technology is adopted to solve the thorny problem of square deep hole machining. The distribution of the electrolyte flow field in the electrochemical machining gap of the deep square hole is simulated with the COMSOL simulation software based on the establishment of the gap electric field and the mathematical model of the gap electrolyte flow field. The simulation results show that the electrolyte flow field distribution in the machining gap is uneven and the electrolyte is not full. Therefore, the cathode structure in the corresponding machining gap area is optimized by the c o s θ method. The two-section square cone combination cathode with the bi-directional liquid supply is designed, and two groups of 16 added liquid holes with a diameter of 1.5 mm, a slope of 20° and an angle of 22.5° are adopted to improve the flow field distribution. After optimization, the extreme value of current density on the anode surface of the workpiece is reduced from 9.4 to 1.7 A/cm2, which significantly improves the uniformity of current density distribution. Finally, orthogonal experiments are conducted with different voltages, duty cycles, inlet flow rates and feed rates to obtain the experimental results of square hole size and surface roughness. The machining process parameters are selected by the grey correlation method: voltage 17 V, duty cycle 55%, an inlet flow rate of 20 m/s and feed rate 0.4 mm/min. The dimensions of the specimens meet the product requirements, enabling stable processing of square deep holes, significantly shortening the cathode design cycle and optimising the cathode structure. [ABSTRACT FROM AUTHOR]