This paper presents a systematic method for kinematic modeling and improving the positioning accuracy of a compound machine tool. With the configuration of model frames and the adjustment of the link offset parameters, the position and orientation of the tool center point (TCP) are measured conveniently by a laser tracker, and the forward kinematic solution of the machine model is provided. Through the Levenberg-Marquardt (L-M) algorithm combined with chi-square fitting, the maximum likelihood estimators of the model parameters are obtained. The identified parameters indicate a certain squareness error between the linear and adjacent rotary axes, and each coordinate axis has a certain angular error. The link length parameter also has a slight error. The calibration result shows that the average position and orientation error of the machine tool are 0.03999 mm and 6.571 × 10^-4 rad respectively, which are 79.6% and 44.9% lower than the initial error, indicating that the volumetric accuracy of the machine tool has been greatly improved through parameter identification. Compared with rigid body kinematics or screw theory modeling, the Denavit-Hartenberg (D-H) combined with Hayati-Mirmirani (H-M) modeling method used by the compound machine tool has a clear geometric meaning of the model parameters, and there is no need to measure the single geometric error of the coordinate axis. It has the advantages of fewer modeling steps and short test time. The volumetric error modeling, accuracy measurement, and parameter identification proposed in this paper are beneficial in improving the volumetric accuracy of machine tools with special structure.

Additive manufacturing (AM) is attracting more and more interests due to its high material utilization and great flexibility in product design. WAAM is characterized by its ability to manage various metallic materials and high deposition speed. However, its shape accuracy is lower than that of its accumulation via other AM processes and finishing is required as a post-process. In addition, accumulations by AM composed of metal have a complicated thermal history owing to repeated melting and rapid solidification. Consequently, dendritic growth occurs in the microstructure of its accumulation using SUS316L austenitic stainless steel. Therefore, compared with equigranular structures, the mechanical properties of stainless steel, such as ductility and yield strength, are anisotropic. Hence, we herein propose a new system that combines wire and arc additive manufacturing (WAAM) and finishing processing systems. In this method, finishing is performed by the rotating tool when the molten metal solidifies. Experiments using the new system are performed to suppress an anisotropic microstructure by the accumulation of WAAM. As a rotary tool, a cutting tool and a friction stir burnishing (FSB) tool are used. Microstructure observation and X-ray diffraction analysis are performed to evaluate the anisotropy of the accumulation. Using the new system, dendritic growth can be suppressed in an accumulation. By applying the abovementioned simultaneous processing system to the outermost layer of WAAM deposition, improvement in fatigue strength via surface modification and simplification of the finishing process are expected.

The objective in planar four-bar motion generation is to calculate the linkage dimensions required to achieve a group of prescribed coupler positions. For a given planar four-bar motion generator however, the rolling motion of its moving centrode over its fixed centrode will replicate its coupler motion. The curvature of the fixed and moving centrodes can be incorporated as contact surfaces in a rolling cam system to replicate the coupler motion of a planar four-bar motion generator. While the advantages that cam-based systems have over four-bar linkage-based systems are application-specific, some of the advantages relate to system workspace (having a more compact design), structural soundness (having a greater load bearing capacity) and design simplicity (utilizing fewer components). While design methods for cam-based systems have been developed for conventional non-adjustable four-bar motion generators, no such method has been presented for the adjustable planar four-bar motion generator. Given the design advantages associated with cam-based systems along with an absence of published work in the design of cam-based systems for adjustable motion generation, an opportunity exists to contribute to the body of knowledge in this area. This work presents for the first time a design method for a dual cam system to replicate the coupler motion of an adjustable planar four-bar motion generator. This design method incorporates an optimization model for defect-free adjustable planar four-bar motion generation. The adjustments considered in the optimization model are adjustable crank and follower moving pivots with adjustable crank and follower link lengths. This design method also incorporates centrode generation equations for the adjustable planar four-bar motion generator. As an example, the centrodes generated for a calculated adjustable motion generator were incorporated into a computer-aided design model to produce a concept dual cam system.

A meshing cycle of normal contact ratio gear can be divided into three stages, i.e., double pairs of teeth meshing, single pair of teeth meshing and double pairs of teeth meshing. In many previous literatures, for the convenience of research, the dynamic model based on a pair of teeth was usually used to express the dynamic behavior of all pairs of teeth in the entire meshing cycle, which will cause the problem that the established dynamic model cannot fully reflect the influence of the meshing state of each pair of teeth on the dynamic characteristics of the system. Therefore, based on the relevant literature, a nonlinear dynamic model of spur gear pair considering the meshing state of multiple pairs of teeth is proposed in this paper. The new model can fully reflect meshing error, meshing stiffness, backlash of multiple pairs of teeth participating in the meshing at the same time. To compare the differences between the new model and the traditional model, the main factor causing the difference between them is analyzed. Based on the calculation of single pair of teeth and comprehensive meshing error by TCA (tooth contact analysis) method, the effects of different meshing error, contact ratio and meshing damping on the system dynamic characteristics respectively based on the two models are compared and discussed. The results show that the new model can reflect the dynamic behavior of each pair of teeth participating in the meshing at the same time more accurately than the traditional model, especially when contact ratio and meshing damping are large. The new model proposed in this paper lays a foundation for building a more accurate dynamic model of a gear pair (especially the HCR gear pair with the contact ratio greater than 2) and accurately analyzing the dynamic behavior of each pair of teeth in meshing.

In recent years, efficient logistics has become indispensable, and using unmanned aerial vehicles (UAVs) or drones is promising for considerably reducing the cost and time required for parcel delivery. This paper addresses a parcel delivery scheduling problem. In this problem, a truck loaded with drones and parcels leaves a distribution center and stops at some points on a fixed route. At each point, the drones take off and deliver parcels to customers. We define this problem as finding the assignment of customers to both the drones and their takeoff points. Then, we propose a genetic algorithm (GA) for finding a near-optimal solution in a short time. In the proposed GA, a solution is represented using sets of customers assigned to the takeoff points, and a heuristic rule determines the assignment to the drones. The crossover operation enables offspring to inherit the customer sets. Experimental results show that the proposed GA can successfully find an optimal or a near-optimal solution faster than an integer programming solver for almost all instances. In addition, it significantly outperforms other GAs using a different crossover.

An automobile active vibration damping system is mainly consists of a pump-controlled cylinder system with highly responsive, small volume and lightweight, the performance of the friction pair of the hydraulic pump puts forward high requirements. A compact and lightweight gerotor pump was designed, and the characteristics of the friction pair and the noise of the rotor and valve plate materials were investigated in this study. Tribological experiments were conducted on different materials with and without surface microtexture distribution pair. Results show that the steady-state average friction coefficients of Poly-Ether-Ether-Ketone (PEEK) without and with microtexture surface are 0.059 and 0.044, respectively, and the friction coefficient reduces by 25.4%. Lead bronze without and with microtexture surface are 0.137 and 0.103, the friction coefficient reduces by approximately 24.8%. Inner and outer rotor noise experiments show that different materials have different effects on reducing the noise at different speeds. The gerotor pump noise ranges from high to low in the order: 9Cr18/9Cr18>9Cr18/PEEK>PEEK/PEEK. The active vibration damping system gerotor pump using PEEK can reduce the noise, compared with the inner and outer rotors using 9Cr18, the noise of gerotor pump only inner rotor uses PEEK is reduced by 2.78% and 0.78% at 1000 rpm and 5000 rpm, both of rotors uses PEEK can reduce the noise 4.5% and 2.57% at the rotation speed is 1000 rpm and 5000 rpm. The flow characteristics of the gerotor pump with PEEK rotors are studied at the end of the article, as the rotation speed increases, the volumetric efficiency of the pump decreases. Therefore, the selection and surface treatment of these materials are suitable for the active vibration damping system gerotor pump.

The design of pure-rolling gear has always been a subject of intense research, because in some working conditions, such as dry friction, pure-rolling gear has higher transmission efficiency and less possibility of transmission failure. Non-circular gears have played an important role in mechanical devices and robots. To date, there is no effective method to design a pure-rolling non-circular gear with relatively small number of teeth. Based on the space curve meshing theory, a pure-rolling non-circular Line Gear (PNLG) mechanism was presented in this paper. Firstly, the fundamental design method of the PNLG was proposed, which included the derivation of the contact curves, the obtainment of the teeth number and the solution of the rotating angle function. And, the rotating angle function was selected as a segmental quartic curve to ensure the dynamic stability in the meshing process. Afterwards, a pair of PNLG was designed for finite element analysis (FEA) and kinematics experiment. Finally, prototypes of PNLG pair were manufactured by using of 3D printing, and transmission ratios were measured on the test rig. The simulation results and experimental results indicate that the devised PNLG is feasible, that is, the PNLG can smoothly output the preset rotating angle and angular velocity. The designed PNLG mechanism might be used in some special cases, such as the occasion without lubrication and miniature devices.

A novel metal inert gas (MIG) weld-brazing was employed to produce the dissimilar materials butt-joint welds that specimens consisted of 6061 aluminum (Al) alloy and galvanized steel sheet. In this process, the fluxes such as CaF₂, TiO₂, SiO₂ and ZnO powder were coated on the surface of steel respectively to investigate the effect of activating fluxes on the performance of specimens. The experimental results revealed that CaF₂ flux powder was applied as a suitable flux which spreadability of filler material on steel surface become better. In order to obtain better appearances of specimen surface, the coating thickness of flux powder should be accurately control at 0.1 mm. When SiO₂ flux powder was coated on surface of specimen, the amount and the size of porosity decrease simultaneously in the fusion zone (FZ) of weld bead. It led to improve the tensile strength of Al/steel butt-joint specimens. The surface of specimens coating with CaF₂, TiO₂ or SiO₂ flux powder, the thicknesses of intermetallic compound (IMC) layer were less than 10 μm. The specimens produced by coating with ZnO flux may increase the temperature of FZ, the average thickness of IMC layer was 14.62 μm and the IMC layer presents a saw tooth shape.

In order to research the dynamic performance of angular contact ball bearings of high-speed motorized spindles in detail, based on Hertz contact theory and bearing quasi-static model, considering the influence of centrifugal force, gyroscope moment and thermal effect on bearing operation, the modified quasi-static model is established to calculate the bearing contact stiffness. Then, considering the influence of temperature on the dynamic viscosity of lubricating oil, film stiffness model of bearing is also presented. On the basis, the bearing comprehensive stiffness model is proposed, and the influences of combined load and rotational speed on the bearing stiffness are investigated. The results show that as the speed increases, the radial contact stiffness increases, while the axial and angular contact stiffness decrease, the dynamic viscosity of the lubricating oil decreases, the film stiffness decreases and the comprehensive radial, axial and angular stiffness decrease. With the increase of axial load, the radial, axial and angular contact stiffness increase, the comprehensive stiffness increases. When the radial load increases, the radial, axial and angular contact stiffness decreases, while the comprehensive stiffness increases. It is found that the comprehensive stiffness considering the temperature is larger than without consideration of the temperature.

Although axial free floating of the driving pinion can automatically balance the load of the left and right helical gear pairs, it causes its three-dimensional vibration. A new three-dimensional loaded tooth contact analysis (3-DLTCA) model of a double helical gear considering the pinion axial support stiffness is proposed in this paper. Firstly, according to the differential geometry and mechanical analysis, the 3-DLTCA model of a double helical gear is established. The model is based on the deformation coordination condition, force balance condition, non-embedding condition and axial force balance constraint. Secondly, to reduce the three-dimensional loaded transmission error (3-DLTE) and improve the load distribution, a multi-objective optimization mathematical model of a double helical gear is established. Finally, the effects of load, error, pinion axial support stiffness and tooth surface modification on the 3-DLTE of a double helical gear are investigated by employing numerical examples. The results indicate that the new 3-DLTCA model can accurately calculate the 3-DLTE of a double helical gear. By optimizing tooth surface modification and pinion axial support stiffness, the 3-DLTE of a double helical gear can be effectively reduced while considering the uniform load of the left and right tooth surfaces. Moreover, the optimization design method can effectively reduce the three-dimensional vibration of the double helical gear system.

Product color emotion design has become an important new design direction following the development of user-centered design. In this paper, we integrated Kansei engineering (KE) and extreme gradient boosting (XGBoost) algorithm to explore a new evaluation method of product color emotion design. Firstly, based on KE, a user emotion image perception space was established using big data, semantic differential (SD), and factor analysis (FA). Secondly, the product color emotion evaluation model based on XGBoost was established using XGBoost algorithm and experimental data. In application, we established an XGBoost based evaluation model of exercise bike color emotion to verify the effectiveness of this evaluation model. We then analyzed the graph of feature importance which was output by the XGBoost model and learned the weight of each color parameter. Next, we used the case of dust mite controller to verify effectiveness of this color design method in different type product. Moreover, we compared predictions of the XGBoost model, multiple linear regression (MLR) model, and the back propagation neural network (BPNN) model. The result proved that the color emotion evaluation model based on XGBoost had a better performance. All the above results indicated that the product color emotion design method based on XGBoost could effectively reveal the user’s color emotion and help designers make color scheme decisions. So, it has certain applicability and practicability, and this method can be applied to a variety of color design cases.

Nanoindentation is generally used to measure the hardness or Young’s modulus of thin films. However, when the hardness or Young’s modulus is measured on the ultrathin layer, it cannot sometimes obtain exact results due to some influential factors such as wear of indentation tip, surface roughness, or substrate effect. We focused on the elastic modulus measurement method of ultrathin layers using the time-of-flight secondary ion mass spectroscopy (TOF-SIMS) with Ar gas cluster ion beam (GCIB). The dissociated ion yield defined as the intensity ratio (Ar₂⁺/(Ar₂⁺+Ar₃⁺) on the positive ion spectrum and impulsive stress were compared and correlated to be proportional to both on the reference materials. The Young’s moduli of the silicon oxide layer of 1.7 nm thickness on monocrystal silicon wafer and ultrathin diamond-like carbon (DLC) layer with approximately 3 nm thickness on magnetic disks were estimated using the dissociated ion yield measured using Ar-GCIB and correlation result. The Young’s modulus was measured at various depths using Ar-GCIB etching with a very slow etching speed. We confirmed a difference between the Young’s moduli of these ultrathin layers and those of under layers. From these results, it was seen that the elastic modulus measurement method using TOF-SIMS with Ar-GCIB is a powerful tool to compare the elastic modulus of ultra-thin layers and improve the accuracy of structural analysis simulations of ultra-thin film structures with nanometer order thickness, which was impossible with conventional methods.

In end milling, proper tool life management is crucially important for achieving highly accurate machining, avoiding tool failure, and optimizing production costs. In recent years, a number of tool condition monitoring (TCM) methods aimed at improving tool life management have been proposed. However, these methods have generally been impractical, and tool life still tends to be determined based on machining time or the quantity of the product produced. To address this shortcoming, a practical online TCM method is proposed. The proposed method is based on the idea that the frictional force acting on the flank face of a tool increases with increasing flank wear resulting from an increase in the contact surface area between the flank face and the machined surface. The implication is that tool wear can be indirectly monitored using the change in frictional force on the flank face, which can be determined by tracking the spindle motor torque obtained using a computerized numerical control (CNC) controller and a real time cutting force simulation. The influence of tool wear is not considered in the simulation model; rather, the frictional force is estimated from the difference between the average predicted cutting torque and the average monitored spindle motor torque. With the proposed method, no additional sensor is needed to monitor tool wear. Additionally, no parameter determination is necessary to perform the simulation because the parameters needed for the simulation are immediately determined at the beginning of the milling operation based on the monitored spindle motor torque. Thus, the TCM method proposed here offers a practical online alternative.