As a potential candidate for the next generation of high-temperature alloys, refractory high entropy alloys (RHEAs) have excellent mechanical properties and thermal stability, especially for high-temperature applications, where the processing of RHEAs plays a critical role in engineering applications. In this work, the wire electrical discharge machining (WEDM) performance of WNbMoTaZr_x (x = 0.5, 1) RHEAs was investigated, as compared with tungsten, cemented carbide and industrial pure Zr. The cutting efficiency (CE) of the five materials was significantly dependent on the melting points, while the surface roughness (Ra) was not. For the RHEAs, the CE was significantly affected by the pulse-on time (ON), pulse-off time (OFF) and peak current (IP), while the surface roughness was mainly dependent on the ON and IP. The statistical analyses have shown that the CE data of RHEAs have relatively-smaller Weibull moduli than those for the Ra data, which suggests that the CE of RHEAs can be tuned by optimizing the processing parameters. However, it is challenging to tune the surface roughness of RHEAs by tailoring the processing parameters. Differing from the comparative materials, the WEDMed surfaces of the RHEAs showed dense spherical re-solidified particles at upper recast layers, resulting in larger Ra values. The proportion of the upper recast layers can be estimated by the specific discharge energy (SDE). Following the WEDM, the RHEAs maintained the main BCC1 phase, enriched with the W and Ta elements, while the second BCC2 phase in the Zr1.0 RHEA disappeared. Strategies for achieving a better WEDMed surface quality of RHEAs were also proposed and discussed.

The cam-linkage mechanism is a typical transmission mechanism in mechanical science and is widely used in various automated production equipment. However, conventional modeling methods mainly focus on the design and dimensional synthesis of the cam-linkage mechanism in the slow-speed scenario. The influence of component dimensions is not taken into consideration. As a result, the model accuracy dramatically falls when analyzing large-size cam-linkage mechanisms, especially in high-speed environments. The kinematic aspects of cam design have been investigated, but there are few studies discussing the motion characteristic and accuracy analysis models of the large-size cam-linkage mechanism under high-speed scenarios. To handle such issues, this paper proposes a parameter optimization methodology for the design analysis of the large-size high-speed cam-linkage mechanism considering kinematic performance. Firstly, the mathematical model of the cam five-bar mechanism is presented. The cam curve and motion parameters are solved forward with linkage length and output speed. Then, a particle swarm-based multi-objective optimization method is developed to find the optimal structure parameters and output speed curve to minimize cam pressure angle and roller acceleration and maximize linkage mechanism drive angle. A Monte Carlo-based framework is put forward for the reliability and sensitivity analysis of kinematic accuracy. Finally, a transverse device of a sanitary product production line is provided to demonstrate the applicability of the proposed method. With the parameter optimization, the productivity of the transverse device is doubled, from 600 pieces per minute (PPM) to 1200 PPM.

For injured and after-stroke patients who temporarily lose their hand’s grasping abilities, assisting them in regaining their index finger mobility is very important in the rehabilitation process. In this paper, a finger rehabilitation device based on one degree-of-freedom (DOF) linkage mechanism is designed, aiming to lead the index finger through the flexion–extension trajectory during grasping tasks. Two types of one-DOF mechanisms, a four-bar linkage and a Watt-I six-bar linkage, are synthesized for the task trajectory. Various algorithms such as PSO, GA, and GA–BFGS are adopted and compared for the synthesis of these two types of mechanisms, among which the Watt-I six-bar linkage obtained with GA–BFGS shows the optimal performance in accuracy. Clinical biomechanical data are utilized to perform static analyses of the mechanisms, and the feasibility of the Watt-I six-bar linkage models is tested, compared, and demonstrated. Finally, the prototype of the six-bar linkage as well as a wearable exoskeleton finger rehabilitation device are designed to show how they are applied in the finger rehabilitation scenario.

We propose a new digital evaluation model for the negative-pressure molding mechanism, which is used to verify the feasibility of improvement measures for quality problem of the pad. The gas–solid flow in the negative pressure molding system facing the pad of diapers at the molding surface under different outlet pressures is studied using CFD-DEM bidirectional coupling simulation method. Aiming at the concentration of velocity/pressure values in the molding defect region, the uniformity coefficient is used as an important evaluation index to reflect the molding quality, and the parameters are optimised for the velocity and pressure uniformity of the gas phase in the molding defect region. For the fine flocculent discrete element, the parameter calibration is carried out, and the percentage of solid phase bearing at the screen is used as a reference index to further verify the feasibility of the improvement scheme. Finally, the model is applied to an improvement example, the results show that the molding defects of the cotton core layer are related to the velocity distribution of the molding surface. The molding quality can be significantly improved by setting a retaining ring at the outlet of the wind barn. The speed uniformity coefficient is improved by 44.2% when the retaining ring thickness s = 140 mm, inner diameter d = 1000 mm, and the relative position l = 0 mm. The molding quality has been significantly improved.

In order to obtain the working state of the brake shearing machine, the paper proposed a monitoring system designed for the key data of the shearing machine such as the throat deformation, the temperature of the shearing cylinder and the vibration of the upper tool holder. The selection and connection of the hardware and the method of setting up the wired and wireless networks of the monitoring system are specified first in this paper. Then the methods of data acquisition and processing are put forward. Finally the functions of the host computer and the cloud server as well as the structure of the software are illustrated in detail. The monitoring system is suitable for the production line which contains many sheet metal machine tools, and it is of reference significance to establish a larger range of machine tool monitoring system.