Reasonable Process Parameters Research Articles

Investigating the Surface Quality of Aramid Honeycomb Materials Through Longitudinal–Torsional Ultrasonic Milling

During the milling process of aramid honeycomb, residual stresses arise, which will affect the surface quality of the honeycomb. Studies have shown that reasonable processing techniques can reduce residual stresses, indicating a close relationship between residual processing stresses and the processing parameters, such as technique. By investigating the changes in residual stresses after the processing of aramid honeycomb materials, the influence of processing techniques on these changes is analyzed. Leveraging the correlation between residual stresses and surface quality, this study proposes the use of residual stress as an indicator for evaluating processing techniques. The longitudinal–torsional ultrasonic vibration milling method is applied to the processing of aramid honeycombs. A single-factor experimental approach is adopted, utilizing ABAQUS 2020 software to mimic the longitudinal–torsional ultrasonic milling process. This study explores the influence patterns of various process parameters on the residual stresses generated during the milling of honeycombs. The simulation results indicate that within the selected range, the residual stress decreases as the tool rotation speed increases, while it increases with the increase in feed rate. The influence of milling depth on residual stress can be negligible. Furthermore, experiments were conducted based on the proposed correlation between residual stress and surface quality. The experimental results show good agreement with the simulation results, indicating that under reasonable process parameters, the residual stress values decrease, thereby improving the milling surface quality of aramid honeycomb materials. Therefore, measuring residual stress can serve as an effective method for evaluating the processing technique.

Correlation between shot peening coverage and surface microstructural evolution in AISI 9310 steel: An EBSD and surface morphology analysis

In this study, martensitic high-strength steel serves as the subject of investigation, with both conventional and severe shot peening experiments being conducted. The coverage levels for conventional shot peening (CSP) are set at 100 % and 200 %, while severe shot peening (SSP) sees levels of 800 % and 1200 %. For the first time, the use of kernel average misorientation (KAM) enables the calculation of geometrically necessary dislocation (GND) density after peening, facilitating the study of GND density distribution across different coverage and offering a method for the visual assessment of peening degree. Results reveal that, under CSP, the gradient distribution of grain size is relatively uniform, whereas SSP leads to a pronounced gradient in grain size distribution. Taking into account the heterogeneous distribution of the initial material microstructure, a gradient in grain size from the surface to the interior of the material will appear after the coverage reaches a certain value, which is 400 % for AISI 9310 steel. Compared with CSP, SSP will further reduce the surface roughness Sa and improve the surface quality. The research presented further understands the relationship between shot peening process parameters and martensitic steel microstructure, providing an important reference for revealing the strengthening mechanism and selecting reasonable process parameters.

Hot compression deformation behavior and microstructure evolution of Al-0.5Mg-0.4Si alloy

The hot compression tests for as-cast Al-0.5Mg-0.4Si alloy were performed on Gleeble-3500 thermo-mechanical simulator under temperatures of 350–500 °C and strain rates of 0.01–10 s−1. Based on the experimental data, a strain-compensated Arrhenius constitutive model was established by exponential function coupling strain. The hot processing map of Al-0.5Mg-0.4Si alloy was established, and the reasonable processing parameters were obtained. The microstructural evolution and dynamic softening mechanisms of the alloy were analyzed using electron backscatter diffraction (EBSD). A detailed description of the evolution of dislocation and the dislocation density during the deformation process was provided. The results indicate that the softening mechanisms of Al-0.5Mg-0.4Si alloy are dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX). The dynamic recovery mechanism is related to the cross slip of the screw dislocation. High temperature and low strain rate are conducive the occurrence of CDRX. This study provides comprehensive guidance for the hot processing of Al-0.5Mg-0.4Si alloy from both macroscopic and microscopic perspectives.

Semi-Solid Forging Process of Aluminum Alloy Connecting Rods for the Hydrogen Internal Combustion Engine

As an important piece of equipment for hydrogen energy application, the hydrogen internal combustion engine is helpful for the realization of zero carbon emissions, where the aluminum connecting rod is one of the key core components. A semi-solid forging forming process for the 7075 aluminum alloy connecting rod is proposed in this work. The influence of process parameters, such as the forging ratio, sustaining temperature, and duration time, on the microstructures of the semi-solid blank is experimentally investigated. The macroscopic morphology, metallographic structure, and physical properties of the connecting-rod parts are analyzed. Reasonable process parameters for preparing the semi-solid blank are obtained from the experimental results. Under the reasonable parameters, the average grain size is 41.48~42.57 μm, and the average shape factor is 0.80~0.81. The yield strength and tensile strength improvement ratio of the connecting rod produced by the proposed process are 47.07% and 20.89%, respectively.

Evaluation Method of Generatrix Straightness Coefficient and Application in AZ31 Magnesium Alloy Panel

Abstract An evaluation method of the generatrix straightness coefficient for magnesium alloy panel is proposed. The generatrix straightness coefficient and characterization parameter are defined. The reasonable process parameters for equal curvature grid panels were determined, and various specifications of magnesium alloy grid panels were processed. For the magnesium alloy grid panel, with an increase in the curvature radius of the panel, the deviation of generatrix straightness and generatrix straightness coefficient of each point is reduced. The deviation of generatrix straightness at the junction of the transverse is the smallest. The deviation of generatrix straightness at the center of the grid is the maximum. The deviation of generatrix straightness at the junction of transverse and longitudinal ribs was minimal. The maximum deviation of generatrix straightness is 0.097 mm, and the maximum generatrix straightness coefficient is 0.277%.

Impact of fully rotating steel casing bored pile on adjacent tunnels

Abstract Based on the theoretical model of a soil plug column, the stress analysis of the soil plug column during the spinning process of steel casing is carried out, and the critical depth of the soil column is determined using the stress and torsional shear ratio of the soil column. The effect of factors such as casing wall thickness, surface load, and steel casing spinning speed on the critical depth of soil columns has been explored, and more reasonable construction process parameters have been obtained quantitatively. Combined with the construction of small net distance test piles at a distance of 2.5 m from the tunnel, the impact of the construction process on the existing shield tunnel has been explored. The results indicate that during the construction process, when the wall thickness of the steel casing does not exceed 0.012 m, the surface load does not exceed 15 kPa, the spinning speed of the steel casing is maintained at 5/4/2/4 m/h or 5/3/2/3 m/h (corresponding to soil depths of 2.5/9.5/6/14 m), and the soil height of the soil column is controlled within 11 m, it is not easy to generate soil plug inside the steel casing, and the soil column has strong torsional shear resistance. According to the measured data of adjacent tunnels, it has been found that the construction method of fully rotating steel casing bored pile can effectively reduce the impact on adjacent shield tunnels, and has a good microdisturbance effect, which can control tunnel deformation not exceeding 1 mm and maintain within the warning value range.

Failure analysis for outer ring cracking of GCr15 rolling bearing

The purpose of this study analysis is to explore the reasons for the outer ring cracking of GCr15 rolling bearing. The failure mechanism was studied through observation of its microstructure and fracture morphology. The analysis results reveal that the main failure reason for the bearing was that the surface secondary quenching layers and network carbides caused the formation of cracks. In order to prevent failure, reasonable grinding process parameters, forging process parameters and normalizing heat treatment before spherodizing annealing were suggested.

Effect of laser cleaning on adhesive properties of carbon fiber composite materials

A pulsed fiber laser was used to conduct laser cleaning experiments on the composite paint layer on the surface of carbon fiber composite materials (carbon fiber-reinforced plastic (CFRP)). The influence of laser energy density and laser travel speed on the cleaning effect was studied. The surface morphology, surface roughness and phase composition of the cleaned sample were analyzed. After bonding, tensile testing was conducted on the bonding part to verify the impact of laser cleaning on the bonding performance. The research results indicate that the cleaning effect gradually improves with the increase of laser energy density or the decrease of travel speed. In this experiment, when the laser energy density is 4.00[Formula: see text]J/cm2 and the travel speed is 6.5[Formula: see text]mm/s, the phase composition of the cleaned substrate surface is only C, without TiO2 and BaSO4. This indicates that the paint layer has been completely removed under this process parameter. By selecting reasonable process parameters, the surface paint layer of CFRP can be effectively removed, and a good surface morphology can be obtained without damage to the carbon fiber. Meanwhile, the mechanical properties after bonding can be improved.

Effect of process parameters on surface quality and bonding quality of brass cladding copper stranded wire prepared by continuous pouring process for clad

Brass cladding copper stranded wire with an outer diameter of 10 mm and core material of d2.12mm × 7 strand was prepared by solid-liquid composite method with continuous pouring process for clad. Compared with the cladding welding method which requires multiple drawings to make the composite welding wire achieve metallurgical bonding, it saves a lot of manpower and material resources and shortens the production cycle. The bonding mechanism of brass and copper was analyzed by experiments, meanwhile, the effects of brass melt temperature and casting speed on the surface quality and interface bonding quality of the composite wire were investigated. The results show that, on the one hand, increasing the melt temperature of brass and reducing the casting speed can inhibit the surface defects of the composite. On the other hand, reducing the temperature of the brass melt and increasing the casting speed can inhibit the excessive element diffusion at the bonding interface, thereby reducing the degree of surface erosion of the copper strand. The final reasonable process parameters are as follows: the brass melt temperature is 970 °C–990 °C, the traction speed is 40 mm/min∼80 mm/min, and the cooling water volume of the crystallizer is 450L/h. The prepared brass cladding copper stranded wire has good quality, Vickers hardness is between 80 - 85HV, and tensile strength is between 265 - 297 MPa. Elongation after fracture is 40.3%∼43.9%, conductivity is 53.8–62.1% IACS.

Densification Behavior and Build Quality of Duplex Stainless Steel Fabricated by Laser Powder Bed Fusion

A systematic study on the densification behavior and build quality of 2205 duplex stainless steel fabricated using laser powder bed fusion (LPBF) was performed by experiment and simulation, aiming to offer some supplementary work for research on additive manufacturing (AM) of duplex stainless steel. In this study, samples with differing laser powers were prepared, and a highest relative density of 98.87% was obtained. Then, the pore defects and surface morphologies were investigated to unveil densification behaviors during a building process. The relationship between surface morphologies and the formation of pores was discussed. It reveals that the inter-layer printing on these surface defects caused by unreasonable laser power could increase the possibility of inside pore defects and reduce the density of specimens. Particularly, the big spatters could be the cause of lack-of-fusion defects even under sufficient power input. Therefore, adequate intra- and inter-layer bonding under reasonable processing parameters is crucial for densification. The mechanical properties of the specimens prepared with the laser power of 260 W are the highest, and the yield strength, tensile strength, and elongation are 798.68 MPa, 953.63 MPa, and 10.85%, respectively.

Analysis on machining uniformity in reciprocating magnetorheological polishing based on abrasive particle trajectory

PurposeThis paper aims to study the effects of the processing parameters in the reciprocating magnetorheological polishing (RMRP) on abrasive particle trajectory by the simulation analysis, which provides a basis for the machining uniformity of the workpiece.Design/methodology/approachThe principle of the RMRP method is discussed, and a series of simulation analysis of the abrasive particle trajectory are performed to evaluate the effects of the workpiece’s rotational speed, the eccentric wheel’s rotational speed, the eccentricity and the frame gap on abrasive particle trajectory by using the RMRP method.FindingsThe processing parameters have a significant influence on the abrasive particle trajectory, and then the machining uniformity of the workpiece is affected. Under certain experimental conditions, the height difference of workpiece measuring points varies between 4 and 11 µm, and the height difference of equal radial measuring points is less than 1.5 µm by optimizing processing parameters.Originality/valueIn this study, the optimal processing parameters can be obtained by the simulation analysis of abrasive particle trajectory, which can replace the experimental methods to obtain the reasonable processing parameters for the machining uniformity of the workpiece. It provides references for the selection of processing parameter values in magnetorheological polishing process.

The Differences in Microstructure, Microtexture, and Tensile Anisotropy of Ti80 Heavy Plate Across the Thickness

Herein, the differences in microstructure, microtexture, and tensile behavior of the Ti80 heavy plate across the thickness are investigated. The Ti80 heavy plate consists of equiaxed α and transformed β grains with high degrees of recrystallization microstructures. Significant differences are observed in the main texture components between the central and surface zones. The inhomogeneous distribution of hot compression and shear leads to different deformation textures during processing. Due to temperature distribution, the combination of the variant selection mechanism and α–β phase interaction is responsible for the evolution of surface texture, while only the former plays a major role in the center. Final fracture areas of tensile samples show ductile fracture characteristics. The anisotropy behaviors in planar tensile of the Ti80 heavy plate at room temperature are evaluated. They are related to the difficulty of activating prismatic slip and basal slip , which are determined by the crystallographic texture of the material. This work helps to explore reasonable thermomechanical processing parameters and establish rolling schedules to weaken the mechanical heterogeneity across the thickness of near‐α‐titanium alloy heavy plates.

Low‐temperature 3D printing and curing process of continuous fiber‐reinforced thermosetting polymer composites

AbstractThe reported work has developed a methodology of printing and curing continuous fiber‐reinforced thermosetting polymer composites (CFRTPCs) with excellent mechanical properties at low temperatures. First, to print and cure CFRTPCs at low temperatures, a thermosetting polymer system was proposed, consisting of phenol based epoxy resin and curing agent (F‐44/2E4MZ). The rheological properties of the polymer system were analyzed to determine a reasonable printing temperature. Second, the non‐linear Vyazovkin integral method was applied to establish the model‐free kinetics (MFK) of the resin system. MFK can predict the curing degree curves at the characteristic temperatures obtained by extrapolation. Reasonable curing process parameters were determined by analyzing the predicted curing degree curves. Then, CFRTPC samples were prepared with the low‐temperature 3D printing process and the low‐temperature curing process, and the fiber content was found to be 53 wt.%. At last, the mechanical property measurements revealed that the tensile and flexural strengths were 1012 MPa and 929 MPa, respectively. This work can further expand the potential applications of 3D printed CFRTPCs in aerospace and defense industries which require high mechanical properties and temperature safety simultaneously.

Process Study and Application of Hot-rolled Aluminum-Zinc Plating Steel Plate Unit

In accordance with the requirements of hot-rolled aluminum-zinc plating and cold-rolled aluminum-zinc plating mixed line for producing construction steel and the production process characteristics of hot-dip aluminum-zinc products, the critical process control points are put forward by combining theoretical analysis with experimental verification. We should select proper raw materials, ensure the cleanliness of strip steel surface, strictly control the annealing temperature, the temperature of the strip steel entering the zinc pan, the temperature and composition of the plating bath, and explore reasonable and feasible process parameters such as air knife and cooling after plating, so as to produce qualified products. This study is of great significance for the improvement and process control of hot-rolled aluminum-zinc plating plates in steel plate production enterprises.

Experimental study on heat transfer of alfalfa during the vibration-assisted compression

Compression alfalfa into briquettes is an effective way to solve the problem of storage and transportation. In the process of compression, heat is generated, which raises the temperature in the material. The appropriate temperature can improve the quality of alfalfa briquettes. In this paper, the effect of assisted vibration frequency, moisture content, and particle size on the compression temperature were tested. The results showed that when the vibration was applied, the material particle temperature in the mold rose significantly, and the core particle temperature rose faster than the edge temperature. The vibration frequency was the most significant factor affecting heat transfer in the three studied factors. When the moisture content and particle size were constant, the heat transfer effect increased first and then decreased with the vibration frequency, and it had an optimal value at 17 Hz. When the vibration frequency and particle size were constant, the heat transfer effect increased first and then decreased with the moisture content. It had an optimal value of 20%. The experimental results explained the effect of vibration frequency, moisture content, and particle size on temperature variation during alfalfa compression and provided a basis for reasonable process parameters.

Study on the optimal process parameters for stripping the X-ETFE insulation layer of aviation wires by a small semiconductor laser

A reasonable laser wire stripping process parameter set is a prerequisite for high-quality and high-efficiency wire stripping. For the X-ETFE insulated wire used in aviation, this study explores the method of obtaining the optimal stripping process parameters based on a 405 nm wavelength semiconductor laser. Build energy conversion model, mobile heat source model, and finite element simulation numerical model of the laser stripping insulating layer process. Based on the single-factor analysis method, simulate the effect of laser power, scanning speed, and processing time on the kerf width, heat-affected zone width, and cutting seam depth of the insulating layer. The results show that increasing the laser power to improve the stripping efficiency will also increase the width of the kerf and heat-affected zone, and increasing the scanning speed can effectively reduce the kerf width. A reasonable combination of laser power and scanning speed can improve stripping efficiency while ensuring quality. According to the single-factor simulation analysis results, select the possible value levels for each parameter to carry out the actual laser wire stripping orthogonal test. There is a good correspondence between the range analysis results of the test data of each stripping quality evaluation index and the conclusions obtained from the single-factor simulation, which verifies the reliability of getting the optimal combination of laser stripping process parameters through the orthogonal test.

An efficiency and quality based automatic drilling-riveting system for aero-structures assembly

Considering the constantly increasing demand for aircraft products, the development of automatic drilling-riveting machine tool systems is discussed in this paper. A structural conceptual design method considering both efficiency and quality is proposed. Particularly, a drilling-riveting machine tool system including single-column machine tool, light-weight end-effector, and assisting fixture system is built. The positioning error coordinates variation model is analyzed, and the ranges of reasonable processing parameters are determined. An experiment is conducted on the developed system to show satisfactory drilling-riveting quality and efficiency: compared with the position error of other similar systems, the position error with 0.082 mm is reduced by 41.42%, and the accuracy of aperture reaches H8, the rivets head height error ≤0.8 mm, and drilling and riveting efficiency can reach 6/min and 8/min.

Prediction of surface roughness of CO2 laser modified poplar wood via response surface methodology

Due to the advantages of short treatment period, no wastewater and oil produced, the CO2 laser is applied as an environment friendly thermal treatment for wood materials to improve the wood properties, such as appearance, color and wettability, among others. However, the morphological features of treated wood surface are also changed, which have negative effects on wooden product properties. To reveal the change tendency of surface roughness during laser irradiation, the common indexes of average roughness (Ra) and mean peak-to-valley height (Rz) were chosen to evaluate the surface roughness. The response surface methodology was selected to arrange the experiments and analyze the influences of laser parameters on surface roughness. The results showed that the poplar wood got rougher with the increased laser power, but the surface roughness decreased with increased feed speed and path spacing, due to the total heat absorption varied under different combination of laser parameters. The ANOVA results showed that the selected quadratic models for Ra∥, Rz∥, Ra⊥and Rz⊥were significant due to the values of probability value (“Prob>F”) less than 0,05. In this case, all the input laser parameters were also the significant model terms for variation of surface roughness. The values of correlation coefficient were very close to 1, which meant the selected quadratic models could give accurate prediction of surface roughness for laser treated wood. Therefore, it is of great significance to predict the surface roughness of the modified wood surface scientifically and to guide the selection of reasonable modification process parameters.

Application of CAD/CAM Technology in Electrochemical Relief Design and Processing of Ceramic Art

Ceramic relief modeling design and CNC machining programming have a wide range of applications in industrial production and daily life. In view of the actual needs of enterprises, this research studies the CAD simulation technology of ceramic relief and achieves the modeling of other pieces of relief based on the geometric outline of the plane breakthrough. According to geometric relief modeling, bitmap relief modeling, tool path selection, and relief simulation processing, the establishment of a ceramic relief model is realized. Finally, the simulation processing is carried out on the ArtCAM software platform, and reasonable processing parameters are obtained to realize the CNC engraving processing of ceramic relief. The experimental results show that the machining efficiency of the ceramic relief model established in this study is improved by 11.3% and 42.8%, respectively, compared with the two traditional methods, which verifies the correctness and superiority of the designed model.

Numerical Simulation and Multi-Objective Parameter Optimization of Inconel718 Coating Laser Cladding

Aiming at the difficulty of temperature control in the laser cladding process of high-temperature nickel-based alloys, the influence of cladding parameters on the temperature of the molten pool, and the quality of the cladding layer were explored. Firstly, through the analysis of the finite element method, the Inconel718 single-pass cladding model was established on the surface of 45 steel by using parametric language and life–death element technology, the influence of different laser power and scanning speed on the temperature of the molten pool center was explored, and reasonable process parameters scope were selected. Secondly, taking the cladding parameters as independent variables, and taking the dilution rate and forming coefficient of the cladding layer as the response variables, using BBD (Box–Behnken Design) to design experiments the response surface analysis method was used to establish the regression prediction model of the cladding process parameters and response indicators, and the genetic algorithm was used to carry out multi-objective optimization to obtain the best results. The optimal parameter combination is a laser power of 1756 W, a scanning speed of 19.43 mm/s, and a powder feeding rate of 19.878 g/min. Finally, a multi-pass lap joint experiment was carried out with the optimal parameters, and it was found that the cladding layer has a dense and fine structure and a good metallurgical bond with the matrix, which can effectively guide the actual production.