Profile Design of the Grooved Die and Rolling Force Prediction in the Cold Pilger Rolling Process

The objective of this study was to design the die groove profile and predict the rolling force produced when employing the variable curvature rolls and mandrel for manufacturing seamless pipes using the cold pilger rolling process. The parameters of the key process design were the diameter of the initial tube and final product, as well as the feed amount, reduction area, principal deformation zone, and roller radius. The rolling forces during the pilger rolling process were theoretically calculated to enable their prediction, and the characteristics of the cold pilger rolling process were identified. The calculated values were in close agreement with the experimental data. The die groove design is important in the prediction process because the dimensional accuracy of the tubes and the life of the dies are highly dependent on this design. The presented design method can be successfully applied to fulfill this objective. The tube shape and adequate tolerance can be attained by using the proposed design method. The mechanical properties of the pipe are evaluated by calculating the Q factor.

Variable Curvature Modelling Method of Continuum Robots with Contraints

The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human-robot interaction. This compliance reduces the risk of damage to the manipulated object and the surroundings. However, continuum robots have theoretically infinite degrees of freedom, and this high flexibility usually leads to complex deformations with external forces and positional constraints. How to describe this complex deformation is the main challenge for modelling continuum robots. In this study, we investigated a novel variable curvature modeling method for continuum robots, considering external forces and positional constraints. The robot configuration curve is described by the developed mechanics model, and then the robot is fitted to the curve. To validate the model, a 10-section continuum robot prototype with a length of 1 m was developed. The ability of the robot to reach the target points and track complex trajectories with load verified the feasibility and accuracy of the model. The ratio of the average position error of the robot endpoint to the robot length was less than 2.38%. This work may serve a new perspective for design analysis and motion control of continuum robots.

Trajectory Prediction of Three Dimensional Forming Tube Based On Kalman Filter

This article focuses on the prediction of forming trajectory and process optimization during the forming process for the variable curvature tubes. Firstly, through cubic B-spline interpolation, the geometric characteristics of the axis of the target tube are obtained. An overall tube is "separated and then integrated", and the relationship between geometric parameters and processing parameters is established to obtain the initial process parameters. Based on the Extended Kalman Filter (EKF) algorithm, the motion model and observation model of tube forming using simulation are presented section by section, and the relevant calculation and analysis are carried out. The forming trajectory has been predicted and the processing parameters are optimized during the processing process, in which the effectiveness of the processing optimum scheme is illustrated.

Striated Tire Yaw Marks—Modeling and Validation

Tire yaw marks deposited on the road surface carry a lot of information of paramount importance for the analysis of vehicle accidents. They can be used: (a) in a macro-scale for establishing the vehicle’s positions and orientation as well as an estimation of the vehicle’s speed at the start of yawing; (b) in a micro-scale for inferring among others things the braking or acceleration status of the wheels from the topology of the striations forming the mark. A mathematical model of how the striations will appear has been developed. The model is universal, i.e., it applies to a tire moving along any trajectory with variable curvature, and it takes into account the forces and torques which are calculated by solving a system of non-linear equations of vehicle dynamics. It was validated in the program developed by the author, in which the vehicle is represented by a 36 degree of freedom multi-body system with the TMeasy tire model. The mark-creating model shows good compliance with experimental data. It gives a deep view of the nature of striated yaw marks’ formation and can be applied in any program for the simulation of vehicle dynamics with any level of simplification.