Wire and arc additive manufacturing is one of the additive manufacturing processes based on arc welding technology and is particularly useful in fabricating large-sized die and prototype machine parts. In general, a computer-aided manufacturing (CAM) system is required not only to generate the deposition path as a numerical control data but also to estimate the shape of the build structure. Estimating the build structure before the actual fabrication can help determine the optimal process parameters. However, the build structure simulated using the existing CAM system may not be sufficiently accurate, because the bead geometry is influenced by various factors, such as the process parameters, material type, target shape, and the location in which the molten metal is deposited. In this scenario, it is challenging to obtain the optimal process parameters based on the build structure simulation results. Therefore, in this study, a two-dimensional bead cross-section model was established, in which the bead accumulation was considered to fabricate a shell structure, and a build shell structure simulator was developed. The temperature distribution was numerically simulated to obtain the relationship between a process parameter and the bead cross-section geometry without conducting destructive inspection. Furthermore, the accuracy of the simulator was investigated. The results indicated that the accuracy of the simulator was approximately ±1 mm in the area with a low influence of the deposition start and stop processes.

This study mainly aims to ensure the safety of elderly people with a walking assistive device during ground-stair transition. A system that could automatically transfer the walking mode of the assistive device after detecting the ground or stairs is proposed in this research. The assistive device utilizes impedance control to track the predefined walking motions (level and stair walking) that belong to healthy people. Therefore, the target user could be taught to walk safely while being assisted. Collisions and falls can easily happen during the transition from even ground to stairs. Thus, we propose a distance-detection system using ultrasonic sensors mounted at the toe and the heel of the feet to detect the changes in road conditions. Accordingly, the previous walking pattern automatically converses to stair climbing or level walking when the assistive device walking on the ground finds the stairs ahead or detects the ground during stair walking. The device motion is changed by switching the target trajectories. The walking trajectories during the transition for different roads are combined. When walking on stairs that are dangerous for the user, the gait is adjusted to prevent tripping and missing steps based on the measured distance from the feet to the stairs. The effectiveness of the system is verified through simulations and experiments. In the simulations, the device target trajectories could be successfully changed when the device walks toward distinct road conditions from any distance. Three subjects participated in the experiments on two types of stairs. The experimental results show that compared with the normal walking of subjects, the foot height increases after assistance, which makes stair walking safer. In conclusion, this method can solve the adaptability of walking assistive devices to different surroundings.

Cooling technology is vital in manufacturing industry, which can decrease cutting temperature, assist chip removal and reduce or eliminate the generation of cutting liquid waste during metal cutting process. This paper presents a novel turning tool cooled by combining circulating internal cooling with spray cooling, which can cool the cutting tool tip from inside and outside of insert and assist blow chips away from cutting zone. Thermal-fluid-solid coupling analysis using ANSYS Fluent is employed to investigate cooling performance of the composite cooling turning tool. Optimization of the internal spray cooling structure is carried out by Taguchi Method based CFD simulations and the optimal geometric parameters are picked out. The prototype of the novel turning tool is fabricated through the integration of spray cooling technology into the previously developed circulating internal cooling turning tool. The cooling effectiveness and practicality of the proposed novel turning tool system are further examined and validated by cutting trials.

Dry drilling gives a higher request to the anti-friction property of cutting tools. However, most tool coatings commonly have less lubricant effect. In present paper, WS₂/Cr layer was deposited on AlCrN layer by a radio frequency magnetron sputtering system, forming the WS₂/Cr-AlCrN lubricant-hard coatings. Its microstructure was studied using scanning electric microscope (SEM) and X-ray diffraction (XRD). Dry sliding tests were carried out against Ti6Al4V balls to evaluate the lubricant effect of the lubricant-hard coatings with different Cr contents in WS₂/Cr layer. Dry drilling performance of WS₂/Cr-AlCrN coating was also studied compared with uncoated and AlCrN coated tool in dry drilling of Ti6Al4V and 7075Al. It is found that as Cr contents increased, WS₂/Cr became denser but the crystallinity decreased. The coating with Cr content of ~9.8 at.% had the best lubricant effect with the lowest friction coefficient and the narrowest wear track. Dry drilling tests show that WS₂/Cr-AlCrN coated tool had the longest tool life and produced the lowest surface roughness. The high wear resistance of AlCrN layer was mainly played near cutting edge. While the anti-friction role of the lubricant layer was mainly played on drill flute, resulting in less material adhesion and improved chip removal.

Human beings communicate using more than verbal communication. To communicate smoothly, humans tend to use nonverbal information such as nodding during embodied interactions. Nodding is a form of affirmative gesture that is commonly used by humans worldwide while communicating with each other. The accurate detection of nodding is expected to support communication, analyze a conversation scene, and facilitate embodied interaction. In contrast, nodding is known to be related not only to the motion of the head but also to the rhythm of the voice. By using both head motion and voice rhythms, nodding can be estimated more accurately than methods that use only head motion or voice rhythms. Therefore, in this study, we develop a nodding detection system based on head motion and voice rhythm. In this system, the head motion of the listener is measured using face tracking. Then, the nodding motion is estimated using a neural network for head motion. Furthermore, the neural networks estimate the timings at which the listener is nodding by using the voice of the speaker. Subsequently, the nodding is estimated using logical OR and logical AND based on outputs of the head movement and speech rhythm neural networks. In addition, a neural network that integrates head motion and voice rhythm is developed. Furthermore, the effectiveness of the developed methods is demonstrated through evaluation experiments.

In this paper a method to calculate machine tool setting parameters for spiral bevel gars by duplex helical method is proposed, in which contact path is predesigned. Firstly, machine setting parameters and curvature parameters in reference points of gear are calculated; secondly, curvature parameters of technology and cut in reference points of pinion are calculated based on meshing theory; then, machine tool setting parameters of pinion are calculated on the basic of the relationship of curvature parameters of technology and cut. Mathematic models of tooth contact analysis and ease-off topology are established to check out the machine tool setting parameters. An example is presented that machine tool setting parameters are calculated based on the method proposed in this paper, which predesign contact paths are 45°, 60°, and 70° respectively. The contact path of TCA results exist errors are less than 0.5% comparing to predesign; the results achieve the design requirement. Finally a cut experiment is carried out which the predesign of contact path is 70°; the results of rolling test are consistent with results of TCA. The correctness and validity of the method is verified.

Robotic systems are widely applied in manufacturing industry to reduce labor cost and increase productivity. Due to the influence of different observed factors (e.g., controllable robotic settings) and the unobserved heterogeneity caused by the unobserved/unknown factors (e.g., material non-uniformity, geometry variability of assembly units) during the assembly process, the assembly time of assembly units exhibits highly heterogeneous performance. To improve the productivity of the assembly process, it is important to develop an analytics-based model to provide accurate assembly time prediction of assembly units and further identify the potential influencing factors for further process improvement. This paper proposes a full Bayesian modeling approach to predicting the performance of heterogeneous robotic assembly time data. Specifically, a generic statistical model is provided to characterize the heterogeneous assembly time data of a heterogeneous population of assembly units by considering the influence of both observed factors as well as unobserved heterogeneity. Bayesian sampling algorithm is further developed to address a series of parameters estimation challenges, such as highly correlation among parameters from different sub-populations and non-conjugate priors. With the developed Bayesian estimation algorithm, both the influence of observed factors as well unobserved heterogeneity can be jointly quantified with both point estimates and exact internal estimates obtained. Both the numerical and case studies are further provided to justify the validity of the proposed modeling approach and demonstrate its superior prediction performance. The proposed prediction model with considering the population heterogeneity of assembly units exhibits better assembly time prediction performance as compared to alternative modeling approaches with the restrictive assumption of population homogeneity. Moreover, the proposed model is able to identify the relevant factors and quantify their influence with parameters uncertainty quantification for further performance improvement of the assembly process.

Based on coordinate transformation method, the mathematical model for machining axisymmetric aspheric surface is set up. Parabolic surface is studied. The functional relationships between workpiece parameter, tool parameter, cutting state parameter and machine tool performance parameter are analyzed. The variation laws of key technical indexes such as the position of tool locating in vertical direction, the maximum vector height and aperture of parabolic surface, swing range of tool, the minimum arbor distance of tool locating tool carrier in lateral are deduced. An algorithm on dimensional range of machining axisymmetric aspheric surface for machine tool is presented. It can be estimated swiftly that whether the machine tool could do it before machining axisymmetric aspheric surface by means of inputting structure parameters of axisymmetric aspheric surface and motion ranges of machine tool. The simulation experiment results show the validity of the algorithm, which facilitates the machining of axisymmetric aspheric surface.

Packaging boxes are often sealed by a paperboard based flap and also processed so as to have a zipper band (pull tab) structure near the flap. The zipper band structure is used for opening the flap by tearing zipper dash lines which are cut off by using a repeatedly nicked (perforation formed) wedge blade. There are empirically various design patterns of zipper band. In order to arrange the geometrical design parameters of zipper band, the tearing characteristics of zipper-connecting portions must be clarified. In this work, in order to reveal the tearing strength and the success rate of connecting portions (uncut zones), a length of connecting portions and a width of zipper band were widely changed and the pulling direction (attitude) of clamped end of zipper band was also changed. The relationship between the tearing strength and the across direction of cutting line to the grainy direction of paperboard was investigated. Through the experiment, it was found that in-plane de-lamination and tore protrusion occurred at the connecting portions in the band area. Since this de-lamination seemed to be related to the fault of peeling, the effects of pulling attitude (angle) of clamped end of zipper band on the success rate was discussed. As for the upper critical length of connecting portions, at which the success rate became zero, the upper bound tearing strength was gotten and related to the Elmendorf value.

The present paper describes the geometries of honing wheels used in the final tooth-flank-finishing process of automotive transmission gears. For micro geometries of honed gears to keep their required gear accuracy, improper geometries of a gear-honing wheel cause the dressing interval to be short. That is because stock removals are not uniform over honed tooth flank, then the wear of honing wheel is also not uniform. As a result, micro geometries of honed gears are out of their tolerances. The amount of the stock removal could depend on sliding velocities between tooth flanks of a honed gear and a honing wheel so that uniform sliding velocities could yield uniform stock removals. In this paper, a geometrical approach is proposed to determine geometries of gear-honing wheels for minimizing the sliding-velocity variations. Gear-honing wheels were designed with the proposed method and were tested through honing experiments. The results showed micro geometries of honed gears keep their tolerances within a longer dress interval. Therefore, the proposed method for the determination of gear-honing-wheel geometries could extend the tool lives of honing wheels in mass production.

The molds used in the manufacture of many industrial products are mainly manufactured by cutting with a machining center. Since the cutting time is very long in these cutting processes, it is important to judge the tool life and know the appropriate timing for tool change. The authors of this study have been investigating in-process detection of tool wear using tools and the work material itself as sensors, and good results have been obtained. In this method, since the work material and the cutting edge of the cutting tool themselves become sensors, therefore the detection system can be constructed at low cost and does not affect the actual work. In this study, the focus was on the slip of the AC induction motor for driving the spindle of a milling machine. This detection method can also construct the detection system at low cost and does not affect the actual work. By measuring it, it was possible to investigate whether tool wear can be detected in-process. It was found that there is an excellent relationship between the progress of tool flank wear and the slip of the AC induction motor.

The use of Z-bent parts is increasing in many industrial fields. Moreover, the precision requirements for Z-bent part dimensions are becoming more stringent. Z-bent parts are commonly fabricated by two L- or V-bending processes, which cannot provide satisfactory precision. Therefore, a Z-bending process is needed. However, there are few studies on such processes, especially for asymmetrical Z-bent parts. In the present research, which is focused on the wiping Z-bending process, asymmetrical Z-bending die designs with asymmetrical bend radii and bend angles were investigated by using finite element method (FEM) simulations and laboratory experiments. The results showed that when fabricating the same Z-bent parts, different Z-bending die designs produced different stress distributions and different Z-bent part dimensions. Based upon the obtained results, the following die design recommendations were given. To fabricate asymmetrical bend radius Z-bent parts, the Z-bending die should be designed with the larger bend radius on the punch side; however, the larger bend radius should be set on the die side when the accuracy of the large bend radius is of paramount importance. To fabricate asymmetrical bend angle Z-bent parts, the Z-bending die should be designed with the larger bend angle on the die side to provide better overall precision for the Z-bent part dimensions. To fabricate asymmetrical bend radius and bend angle Z-bent parts, the Z-bending die should be designed with the larger bend angle on the die side to provide better overall precision for the Z-bent part dimensions. This study confirmed that selecting a suitable Z-bending die design is essential to fabricating precise Z-bent parts.