No abstract

The rotary tube piercing (RTP) is the first process of making the seamless tube after producing the desired alloy ingot. There are several approaches to manufacture a seamless tube, but one of the most common types is RTP. This approach covers a wide range of processes that are categorized according to the number and shape of the rollers. On the other hand, each of these types has designed guides in the output and input of the piercing process. In this paper, a new design of the input guide for four types of rollers have been examined and simulated. Thus, four specimens including Diescher and Conical rollers were considered, with the different number of rollers. Results including torque, total force, mandrel wear, temperature distribution, and strain were extracted using FEM simulation. In order to the validation of simulation, the total force and oscillations of applied force within the process have been compared with the experimental results. The results obtained through this simulation, are more in line with the empirical results obtained from previous research. As well as, the FEM simulation confirmed the performance accuracy of the output and input guides of the RTP process. On the other hand, the results indicate that the three-roller Diescher type with 17° feed angle, has the most suitable arrangement for production of seamless tube.

Deformation of shafts and seamless tubes are carried out by a radial forging machine in order to achieve the required dimensions and improve the mechanical parameters of the material. Hence, the study of improving the performance of the radial machine leads to an increase in the quality of the forged tube, while the machine equipment in the process of radial forging will have the least erosion. In this process, the workpiece is surrounded by four tools and during the repeated blows of the die, the desired dimensions of the workpiece are obtained. with regards to the contact surface of the die with the workpiece, the most common tool that faces the highest erosion is the die. Therefore, the improvement of die geometry in order to minimize wear has been investigated in this article. Also, the distribution of die temperature and analysis of die stress during the process has been implemented. Accordingly, three types of die geometries: Flat, Concave and Convex are considered to measure the depth of wear and determine the maximum erosion through 3D finite element simulation and experimental estimates. Therefore, according to the comparison between numerical and analytical results in the case of wear analysis with experimental results, the validation of simulation was confirmed.

Considering the complexity of the radial forging process, the study of dynamic and thermodynamic parameters is of great importance. With the severe deformation of a workpiece in a plastic state, the effects of all parameters affecting the final geometry of the forging pipe need to be optimized. Thus, the mathematical model of the process is based on visco-plastic material, taking into account thermomechanical coupling and the surface properties during forging, including the hardness of the workpiece and friction. The results present the effects of a die angle on residual stress, total wear, and contact force, leading to ideal operating conditions and the ideal design of machine parts. In order to ensure the accuracy of the calculations and predictions made through software, a hardness test was performed experimentally, which showed the hardness curve of the microstructure and the strain of the workpiece. This indicates the consistency and accuracy of the results obtained from both methods. In order to improve the process and the tube employed, using an optimized die is recommended.

The rotary tube piercing (RTP) is the first process of making seamless tube after producing the desired alloy ingot. There are several ways to make a seamless tube, one of the most common being RTP. This approach covers a wide range of processes that are categorized according to the number and shape of the rollers. On the other hand, each of these types has designed guides in the output and input of the piercing process. In this article, a new design of input and output guide for all types of rollers have been examined and simulated. Thus, three specimens including Diescher and Conical rollers were considered with 3 and 2 numbers, respectively. Results including torque, total force, temperature distribution and strain were extracted using FEM simulation. The results obtained through simulation are more in line with the experimental results obtained from previous research. While showing the successful performance of the output and input guides of the RTP process, the results indicate that the 3-roller Diescher type RTP has the most suitable arrangement for seamless tube production.