Advances in Manufacturing

Size effects on process performance and product quality in progressive microforming of shafted gears revealed by experiment and numerical modeling

Jun-Yuan Zheng, Hui Liu, Ming-Wang Fu

2023, 11(1): 1-20. doi:10.1007/s40436-022-00414-0

摘要 ( 2091 )

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As one of the indispensable actuating components in micro-systems, the shafted microgear is in great production demand. Microforming is a manufacturing process to produce microgears to meet the needs. Due to the small geometrical size, there are uncertain process performance and product quality issues in this production process. In this study, the shafted microgears were fabricated in two different scaling factors with four grain sizes using a progressively extrusion-blanking method. To explore the unknown of the process, grain-based modeling was proposed and employed to simulate the entire forming process. The results show that when the grains are large, the anisotropy of single grains has an obvious size effect on the forming behavior and process performance; and the produced geometries and surface quality are worsened; and the deformation load is decreased. Five deformation zones were identified in the microstructures with different hardness and distributions of stress and strain. The simulation by using the proposed model successfully predicted the formation of zones and revealed the inhomogeneous deformation in the forming process. The undesirable geometries of microgears including material unfilling, burr and inclination were observed on the shaft and teeth of gear, and the inclination size is increased obviously with grain size. To avoid the formation of inclination and material unfilling, the punch was redesigned, and a die insert was added to constraint the bottom surface of the gear teeth. The new products had then the better forming quality.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00414-0

CBN grain wear and its effects on material removal during grinding of FGH96 powder metallurgy superalloy

Ben-Kai Li, Biao Zhao, Wen-Feng Ding, Yu-Can Fu, Chang-He Li, Rong Wang, Yan-Jun Zhao

2023, 11(1): 21-38. doi:10.1007/s40436-022-00412-2

摘要 ( 2013 )

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Grinding with cubic boron nitride (CBN) superabrasive is a widely used method of machining superalloy in aerospace industries. However, there are some issues, such as poor grinding quality and severe tool wear, in grinding of powder metallurgy superalloy FGH96. In addition, abrasive wheel wear is the significant factor that hinders the further application of CBN abrasive wheels. In this case, the experiment of grinding FGH96 with single CBN abrasive grain using different parameters was carried out. The wear characteristics of CBN abrasive grain were analyzed by experiment and simulation. The material removal behavior affected by CBN abrasive wear was also studied by discussing the pile-up ratio during grinding process. It shows that morphological characteristics of CBN abrasive grain and grinding infeed direction affect the CBN abrasive wear seriously by simulation analysis. Attrition wear, micro break, and macro fracture had an important impact on material removal characteristics. Besides, compared with the single cutting edge, higher pile-up ratio was obtained by multiple cutting edges, which reduced the removal efficiency of the material. Therefore, weakening multiple cutting edge grinding on abrasive grains in the industrial production, such as applying suitable dressing strategy, is an available method to improve the grinding quality and efficiency.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00412-2

Flexible servo riveting system control strategy based on the RBF network and self-pierce riveting process

Yan Liu, Qiu Tang, Xin-Cheng Tian, Long Cui

2023, 11(1): 39-55. doi:10.1007/s40436-022-00403-3

摘要 ( 2038 )

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As more and more composite materials are used in lightweight vehicle white bodies, self-pierce riveting (SPR) technology has attracted great attention. However, the existing riveting tools still have the disadvantages of low efficiency and flexibility. To improve these disadvantages and the riveting qualification rate, this paper improves the control scheme of the existing riveting tools, and proposes a novel controller design approach of the flexible servo riveting system based on the RBF network and SPR process. Firstly, this paper briefly introduces the working principle and SPR procedure of the servo riveting tool. Then a moving component force analysis is performed, which lays the foundation for the motion control. Secondly, the riveting quality inspection rules of traditional riveting tools are used for reference to plan the force-displacement curve autonomously. To control this process, the riveting force is fed back into the closed-loop control of the riveting tool and the riveting speed is computed based on the admittance control algorithm. Then, this paper adopts the permanent magnet synchronous motor (PMSM) as the power of riveting tool, and proposes an integral sliding mode control approach based on the improved reaching law and the radial basis function (RBF) network friction compensation for the PMSM speed control. Finally, the proposed control approach is simulated by Matlab, and is applied to the servo riveting system designed by our laboratory. The simulation and riveting results show the feasibility of the designed controller.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00403-3

Exit morphology and mechanical property of FDM printed PLA: influence of hot melt extrusion process

Yan-Hua Bian, Gang Yu, Xin Zhao, Shao-Xia Li, Xiu-Li He, Chong-Xin Tian, Zhi-Yong Li

2023, 11(1): 56-74. doi:10.1007/s40436-022-00405-1

摘要 ( 2015 )

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In order to study the hot melt extrusion process in fused deposition modeling (FDM), this study mainly explores the effects of printing temperature, heated block length, feeding speed on the exit morphology and mechanical properties of FDM printed Polylactic acid (PLA) samples. High-speed camera is used to capture the exit morphology of molten PLA just extruded to the nozzle. According to exit morphology, the outlet states of extruded molten material can be divided into four categories, namely, bubbled state, coherent state, expanding state, and unstable state. Tensile test results show that printing temperature, heated block length and printing speed have significant influence on tensile properties and fracture mode of FDM printed samples. When the heated block length is 15 mm and 30 mm, there is a ductile-brittle transition in fracture mode with the increase of printing speed. The printing process window under different heated block lengths and printing temperatures has been figured out and the distribution of printing process window under different printing speeds has been discussed. There is a maximum printing process window under the heated block length of 30 mm. This finding provides a frame work for performance prediction of FDM printed parts and theoretical guidance for expanding the scope of printing process window.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00405-1

Study on the thermally induced spindle angular errors of a five-axis CNC machine tool

Ji Peng, Ming Yin, Li Cao, Luo-Feng Xie, Xian-Jun Wang, Guo-Fu Yin

2023, 11(1): 75-92. doi:10.1007/s40436-022-00409-x

摘要 ( 2045 )

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Thermally induced spindle angular errors of a machine tool are important factors that affect the machining accuracy of parts. It is critical to develop models with good generalization abilities to control these angular thermal errors. However, the current studies mainly focus on the modeling of linear thermal errors, and an angular thermal error model applicable to different working conditions has rarely been investigated. Furthermore, the formation mechanism of the angular thermal error remains to be studied. In this study, an analytical modeling method was proposed by analyzing the formation and propagation chain of the spindle angular thermal errors of a five-axis computer numerical control (CNC) machine tool. The effects of the machine tool structure and position were considered in the modeling process. The angular thermal error equations were obtained by analyzing the spatial thermoelastic deformation states. An analytical model of the spindle angular thermal error was established based on the geometric relation between thermal deformations. The model parameters were identified using the trust region least squares method. The results showed that the proposed analytical model exhibited good generalization ability in predicting spindle pitch angular thermal errors under different working conditions with variable spindle rotational speeds, spindle positions, and environmental temperatures in different seasons. The average mean absolute error (MAE), root mean square error (RMSE) and R² in twelve different experiments were 4.7 μrad, 5.6 μrad and 0.95, respectively. This study provides an effective method for revealing the formation mechanism and controlling the spindle angular thermal errors of a CNC machine tool.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00409-x

Base position planning of mobile manipulators for assembly tasks in construction environments

Dai-Jun Xie, Ling-Dong Zeng, Zhen Xu, Shuai Guo, Guo-Hua Cui, Tao Song

2023, 11(1): 93-110. doi:10.1007/s40436-022-00411-3

摘要 ( 2179 )

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With good mobility and flexibility, mobile manipulators have shown broad applications in construction scenarios. Base position (BP) planning, which refers to the robot autonomously determining its working station in the environment, is an important technique for mobile manipulators when performing the construction assembly task, especially in a large-scale construction environment. However, the BP planning process is tedious and time-consuming for a human worker to carry out. Thus, to improve the efficiency of construction assembly tasks, a novel BP planning method is proposed in this paper, which can lead to appropriate BPs and minimize the number of BPs at the same time. Firstly, the feasible BP regions are generated based on the grid division and the variable workspace of the mobile manipulator. Then, the positioning uncertainties of the mobile manipulator are considered in calculating the preferred BP areas using clustering. Lastly, a set coverage optimization model is established to obtain the minimum number of BPs using an optimization algorithm according to the greedy principle. The simulated experiment based on a 9-degree of free (DoF) mobile manipulator has been performed. The results illustrated that the time for BP planning was significantly reduced and the number of BPs was reduced by 63.41% compared to existing manual planning, which demonstrated the effectiveness of the proposed method.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00411-3

Improved time-optimal B-spline feedrate scheduling for NURBS tool paths in CNC machining

Yang Li, Fu-Sheng Liang, Lei Lu, Cheng Fan

2023, 11(1): 111-129. doi:10.1007/s40436-022-00413-1

摘要 ( 2122 )

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Feedrate scheduling in computer numerical control (CNC) machining is of great importance to fully develop the capabilities of machine tools while maintaining the motion stability of each actuator. Smooth and time-optimal feedrate scheduling plays a critical role in improving the machining efficiency and precision of complex surfaces considering the irregular curvature characteristics of tool paths and the limited drive capacities of machine tools. This study develops a general feedrate scheduling method for non-uniform rational B-splines (NURBS) tool paths in CNC machining aiming at minimizing the total machining time without sacrificing the smoothness of feed motion. The feedrate profile is represented by a B-spline curve to flexibly adapt to the frequent acceleration and deceleration requirements of machining along complex tool paths. The time-optimal B-spline feedrate is produced by continuously increasing the control points sequentially from zero positions in the bidirectional scanning and sampling processes. The required number of knots for the time-optimal B-spline feedrate can be determined using a progressive knot insertion method. To improve the computational efficiency, the B-spline feedrate profile is divided into a series of independent segments and the computation in each segment can be performed concurrently. The proposed feedrate scheduling method is capable of dealing with not only the geometry constraints but also high-order drive constraints for any complex tool path with little computational overhead. Simulations and machining experiments are conducted to verify the effectiveness and superiorities of the proposed method.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00413-1

Numerical analysis and experimental validation of surface roughness and morphology in honing of Inconel 718 nickel-based superalloy

Chang-Yong Yang, Zhi Wang, Hao Su, Yu-Can Fu, Nian-Hui Zhang, Wen-Feng Ding

2023, 11(1): 130-142. doi:10.1007/s40436-022-00422-0

摘要 ( 2075 )

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Honing is an important technology for machining onboard system parts. The parts are usually made of difficult-to-machining materials, e.g., Inconel 718 superalloy. Honing can improve the finishing accuracy and surface quality. However, the selection of the honing parameters was primarily based on the results of a large number of experiments. Therefore, the establishment of a reliable model is needed to predict the honed surface roughness and morphology, and offers a theoretical direction for the choice of parameters. In the present study, a numerical simulation model was constructed for analysis of the honing process by Python. The oilstone, workpiece surface morphology and motion trajectory were discretized by Python, and the machined surface was obtained by trajectory interference. Firstly, based on the statistical analysis of the surface topography of oilstone, the shape of grains was simplified and the surface topography of oilstone was built accordingly. Then, the initial surface morphology of the workpiece was constructed and the trajectory of grains on the workpiece surface was analyzed, which showed the distribution of the removed material. Meanwhile, the plastic deformation of material was analyzed in the simulation model. The critical depth of three stages of contact between grains and workpiece was calculated by the theoretical formula: scratching, ploughing and cutting. By analyzing the distribution of bulge, the plastic deformation in ploughing and cutting stage was studied. Further, the simulated results of honed surface roughness and morphology were validated and agreed reasonably well with the honing experiment. Finally, the effects of honing process parameters, including grain size, tangential speed, axial speed, radial speed and abrasive volume percentage, on the surface roughness of the workpiece were analyzed by the simulation model.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00422-0

Numerical simulation for the comparison of thermal and plastic material flow behavior between symmetrical and asymmetrical boundary conditions during friction stir welding

Hao Su, Chuan-Song Wu

2023, 11(1): 143-157. doi:10.1007/s40436-022-00408-y

摘要 ( 2071 )

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An accurate description of the contact condition between the tool and the workpiece material is one of the most important issues for expounding the underlying multi-physics coupled mechanism during friction stir welding (FSW) process. In the present study, a novel asymmetrical boundary condition around the tool-workpiece contact interface is proposed for the FSW of AA2024-T4 alloy. A three-dimensional computational fluid dynamics model is employed for the comparison of the coupled thermal and plastic material flow behavior between asymmetrical and symmetrical boundary conditions. Numerical results of heat generation, temperature distribution, tunnel defect formation and material flow streamline during the welding process are quantitatively analyzed. Besides, various experimental measuring methods are utilized to obtain information about temperature, thermal cycle, tool torque and horizontal cross-section around the exiting keyhole. It is revealed that the modeling results of heat flux density and temperature distribution around the pin, as well as material flow characteristics all change significantly for the two models with different boundary conditions. Particularly, the asymmetrical boundary condition is more capable of predicting temperature fluctuation, plastic material flow along the vertical direction, as well as tunnel defect formation during FSW. Therefore, the superiority of the model with asymmetrical boundary condition over the symmetrical one during the numerical simulation of FSW is elucidated.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00408-y

Experimental study on the wear evolution of different PVD coated tools under milling operations of LDX2101 duplex stainless steel

Vitor F. C. Sousa, Francisco J. G. Silva, Ricardo Alexandre, José S. Fecheira, Gustavo Pinto, Andresa Baptista

2023, 11(1): 158-179. doi:10.1007/s40436-022-00401-5

摘要 ( 2056 )

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Duplex stainless steels are being used on applications that require, especially, high corrosion resistance and overall good mechanical properties, such as the naval and oil-gas exploration industry. The components employed in these industries are usually obtained by machining, however, these alloys have low machinability when compared to conventional stainless steels. In this work, a study of the wear developed when milling duplex stainless-steel, LDX 2101, is going to be presented and evaluated, employing four types of milling tools with different geometries and coatings, while studying the influence of feed rate and cutting length in the wear of these tools. Tools used have been provided with two and four flutes, as well as three different coatings, namely: TiAlN, TiAlSiN and AlCrN. The cutting behavior of these tools was analyzed; data relative to the cutting forces developed during the process were obtained; and roughness measurements of the machined surfaces were executed. The tools were then submitted to scanning electron microscope (SEM) analysis, enabling the identification of the wear mechanisms that tools were subjected to when machining this material, furthermore, the early stages of these mechanisms were also identified. All this work was done with the goal of relating the machining parameters and cutting force values obtained, identifying, and discussing the wear patterns that were observed in the coating and tools after the milling tests, providing further information on the machining of these alloys.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00401-5

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