Advances in Manufacturing

Leaching improvement of ceramic cores for hollow turbine blades based on additive manufacturing

Wei-Jun Zhu, Guo-Qiang Tian, Yang Lu, Kai Miao, Di-Chen Li

2019, 7(4): 353-363. doi:10.1007/s40436-019-00273-2

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The precision casting method based on aluminabased ceramic cores is one of the main techniques used to manufacture hollow turbine blades. Additive manufacturing (AM) technology provides an alternate solution to fabricating ceramic cores quickly and precisely. As the complexity of the structure increases and the strength of the material improves, the leaching process of the cores becomes more complicated. This study proposes a compound pore-forming method to increase the porosity of ceramic cores by adding a preformed-pore agent and materials that convert to easy-to-corrode phases. The preformed-pore agents (e.g., carbon fibers) can be burned off during sintering to form pores before the leaching, and the easy-to-corrode phases (e.g., CaCO₃, SiO₂, β-Al₂O₃) can be leached firstly to form pores during the leaching process. The pores formed in the aforementioned two stages increase the contact area of the cores and leaching solution, thus improving the leaching rate. In the current study, the additive amount of the preformed-pore agent was optimized, and the effect of the easy-to-corrode phases on the comprehensive properties of the cores was then compared. Based on this, the corresponding model was established.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00273-2

Smooth particle hydrodynamics modeling of cutting force in milling process of TC4

Xiao-Guang Guo, Ming Li, Zhi-Gang Dong, Rui-Feng Zhai, Zhu-Ji Jin, Ren-Ke Kang

2019, 7(4): 364-373. doi:10.1007/s40436-019-00276-z

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Milling is one of the main methods for processing titanium alloy. At present, the complex process of milling is usually simulated by finite element method, which often has problems in mesh distortion and mesh reconstruction. Therefore, a meshless three-dimensional milling simulation model was established for TC4 titanium alloy using the smooth particle hydrodynamics (SPH) method. Firstly, the established SPH model was analyzed by the LS-DYNA software, and the stress distribution, temperature field, and cutting force during milling were studied under specific conditions. Subsequently, the cutting force was simulated under different cutting parameters and the effects of these parameters on the cutting force were determined. Finally, based on a series of cutting force experiments, the accuracy of the simulation model was verified. This study proves the feasibility of SPH method in the simulation of titanium alloy milling process and provides novel methods for investigating the processing mechanism and optimizing the processing technology of titanium alloys.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00276-z

Multi-objective resource optimization scheduling based on iterative double auction in cloud manufacturing

Zhao-Hui Liu, Zhong-Jie Wang, Chen Yang

2019, 7(4): 374-388. doi:10.1007/s40436-019-00281-2

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Cloud manufacturing is a new kind of networked manufacturing model. In this model, manufacturing resources are organized and used on demand as marketoriented services. These services are highly uncertain and focus on users. The information between service demanders and service providers is usually incomplete. These challenges make the resource scheduling more difficult. In this study, an iterative double auction mechanism is proposed based on game theory to balance the individual benefits. Resource demanders and providers act as buyers and sellers in the auction. Resource demanders offer a price according to the budget, the delivery time, preference, and the process of auction. Meanwhile, resource providers ask for a price according to the cost, maximum expected profit, optimal reservation price, and the process of auction. A honest quotation strategy is dominant for a participant in the auction. The mechanism is capable of guaranteeing the economic benefits among different participants in the market with incomplete information. Furthermore, the mechanism is helpful for preventing harmful market behaviors such as speculation, cheating, etc. Based on the iterative double auction mechanism, manufacturing resources are optimally allocated to users with consideration of multiple objectives. The auction mechanism is also incentive compatibility.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00281-2

Indirect measurement technology of new energy vehicles' braking force under dynamic braking conditions

Sen-Ming Zhong, Gui-Xiong Liu, Jia-Jian Wu, Bo Zeng

2019, 7(4): 389-400. doi:10.1007/s40436-019-00278-x

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Currently, direct braking-force measurement under dynamic conditions requires a considerable modification to the vehicles and has poor compatibility because there are many types of vehicles. Thus, in this paper, an indirect measurement method of new-energy vehicles' braking force under dynamic braking conditions is proposed. The mechanical wheel and axle model at low/idling/high speeds is established using the piston-pressure formula, force transfer in the brake-wheel cylinder, relative movement between the wheel and the roller, among others. On this basis, the relationship between wheel braking force and roller-linear acceleration is further derived. Our method does not alter existing vehicle structures or sensor types. The standard sealing bolt is temporarily replaced with a hydraulic sensor for coefficient calibration. Afterward, the braking force can be indirectly calculated using the roller-linear velocity data. The method has characteristics of efficiency and high accuracy without refitting vehicles.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00278-x

Residual stress model of pre-stressed dry grinding considering coupling of thermal, stress, and phase transformation

Xiao-Liang Shi, Shi-Chao Xiu, Hui-Ling Su

2019, 7(4): 401-410. doi:10.1007/s40436-019-00280-3

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Pre-stressed dry grinding can result in a hardened layer on the part surface while the surface residual stress is controlled. Considering the factors of the thermal field, pre-stress, and microstructural transformation, a proximate model of surface residual stress for pre-stressed dry grinding is established using the ANSYS finite element simulation method and verified through experiment. The variation laws and mechanisms of the residual stress along with the grinding parameters are revealed. Under the comprehensive effect of pre-stress and phase transformation, the residual stress of pre-stressed dry grinding is revealed mainly as compressive stress. This increases as the pre-stress and grinding depth increase. Under the coupling effect, pre-stress has larger influence on the residual stress than the grinding depth. The model can analyze and predict the residual stress of pre-stressed dry grinding in general.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00280-3

Effect of weld faying part groove shape on reduction of inner flash in steel pipe joints fabricated by friction welding

M. Kimura, S. Iwamoto, M. Kusaka, K. Kaizu, Y. Nakatani, M. Takahashi

2019, 7(4): 411-422. doi:10.1007/s40436-019-00274-1

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The groove shape of the weld faying part was investigated to obtain an ideal pipe friction-welded joint that had a fracture in the base metal and no inner flash of it. The steel pipe had inner and outer diameters of 8.0 mm and 13.5 mm, respectively, and the weld faying surface was of a basic flat shape (butt) type. Moreover, stepped and tapered groove shapes were prepared. Pipe groove shapes were welded with a friction speed of 27.5 s^-1 and a friction load of 2.79 kN. Joining phenomena during the welding process were observed, and the tensile strength of joints was evaluated. The joints, that fabricated with flat or step groove shapes, made with a friction time at which the friction torque reached the initial peak did not have the tensile strength of the base metal nor a fracture in the base metal. However, the joints fabricated with a friction time that reached past the initial peak had a large flash, and they contained a fracture in the base metal. In contrast, when joints were made with a gently tapered groove shape with a friction time reaching the time of the initial peak, they achieved a fracture in the base metal, despite having an extremely small inner flash. Therefore, the shape at the weld faying part was capable of reducing the flash exhausted from the weld interface.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00280-3

Nonempirical hybrid multi-attribute decision-making method for design for remanufacturing

Qing-Shan Gong, Hua Zhang, Zhi-Gang Jiang, Han Wang, Yan Wang, Xiao-Li Hu

2019, 7(4): 423-437. doi:10.1007/s40436-019-00279-w

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Design for remanufacturing (DfRem) is the process of considering remanufacturing characteristics during product design in order to reduce the number of issues during the remanufacturing stage. This decisionmaking in DfRem is influenced by the designers' subjective preferences owing to a lack of explicitly defined remanufacturing knowledge for designers, which can lead to indecisive design schemes. In order to objectively select the optimal design scheme for remanufacturing, a nonempirical hybrid multi-attribute decision-making method is presented to alleviate the impacts of subjective factors. In this method, design characteristics and demand information are characterized through the matter-element theory. Coupled with design principles, some initial design schemes are proposed. Evaluation criteria are established considering the technical, economic, and environmental factors. The entropy weight and vague set are used to determine the optimal design scheme via a multi-attribute decisionmaking approach. The design of a bearing assembly machine for remanufacturing is taken as an example to illustrate the practicality and validity of the proposed method. The results revealed that the proposed method was effective in the decision-making of DfRem.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00279-w

Study on the modification of inclusions by Ca treatment in GCr18Mo bearing steel

Hong-Yan Zheng, Shu-Qiang Guo, Meng-Ran Qiao, Li-Bin Qin, Xiu-Jing Zou, Zhong-Ming Ren

2019, 7(4): 438-447. doi:10.1007/s40436-019-00266-1

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The effect of Ca treatment on the modification of inclusions in Al-killed GCr18Mo bearing steel was studied and a thermodynamic and kinetic model was established. The experimental results showed that oxygen content in the steel could be reduced from 120 μg/g to the range 5.5-21.6 μg/g by Al-Ca complex deoxidization at 1 873 K. An appropriate increase in Ca/Al mass ratio is beneficial to reduce the total oxygen content in steel. When the content of dissolved aluminum was in the range of 0.03%-0.3%, with the increase of Ca/Al mass ratio from 0.8-1.6 to 2.4-3.2, the number of inclusions per unit area significantly reduced. In addition, the main types of inclusions were modified from large-sized Al₂O₃ clusters to plastic or semiplastic liquid phase calcium aluminates. The experimental results matched well with the thermodynamic analysis.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00266-1

Real-time predictive sliding mode control method for AGV with actuator delay

Zhi Chen, Jian Fu, Xiao-Wei Tu, Ao-Lei Yang, Min-Rui Fei

2019, 7(4): 448-459. doi:10.1007/s40436-019-00275-0

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In this paper, a predictive sliding mode control method based on multi-sensor fusion is proposed to solve the problem of insufficient accuracy in trajectory tracking caused by actuator delay. The controller, based on the kinematics model, uses an inner and outer two-layer structure to achieve decoupling of position control and heading control. A reference positional change rate is introduced into the design of controller, making the automatic guided vehicle (AGV) capable of real-time predictive control ability. A stability analysis and a proof of predictive sliding mode control theory are provided. The experimental results show that the new control algorithm can improve the performance of the AGV controller by referring to the positional change rate, thereby improving the AGV operation without derailing.

The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-019-00275-0

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