مجله مهندسی ساخت و تولید ایران
سال نهم شماره 12 (اسفند 1401)

The optimal forming of the metallic parts with the lowest required forming force has always been the focus of researchers. In this paper, effective parameters in hydrodynamic deep drawing assisted by radial pressure of cylindrical cups with a flat head with minimum required forming force have been investigated. At first, the necessary experiments were designed using the fractional factorial design of experiment. In this design, maximum fluid pressure, punch velocity, punch nose radius, friction coefficient between punch and sheet, friction coefficient between die and sheet, and die entrance radius were considered input variables. An experimentally validated finite element model was used for performing the designed experiments and extracting the maximum punch force for each experiment. Finally, by using analysis of variance, the main and the interaction effects of the parameters on the maximum punch force were determined. Results showed that the maximum fluid pressure and punch nose radius have the highest influence on the maximum punch force. Decreasing the maximum fluid pressure from 39 to 15 MPa, leads to a decrease of 55% in the maximum punch force. Also, by reducing the punch nose radius from 10 to 2 mm, the maximum punch force decreases by 55%.

Induction of compressive residual stress on the surface thick-walled cylinder is a way to increase the resistance to failure and increase the fatigue life. The shrink-fit process is one of these methods. In this paper, the three-layer shrink fit for the construction of the hot isostatic press cylinders has been analyzed using experiments, analytical modeling, and finite element simulation. The stresses created due to the shrink fit process in cylinders were investigated using analytical calculation and finite element simulation. To perform the shrink fit experimentally, three cylinders were made of VCN steel and the shrink fit operation was performed. Based on the results from the finite element simulation, the maximum radial displacement for the outer cylinder is 0.89 mm and the residual stress value is 39.9 MPa. Also, the comparison of simulation results and analytical method for the middle and outer cylinder shows that the differences were 2.3% and 2.8%, respectively.

Fiber-reinforced composites are widely used in industries due to their high strength-to-weight ratio, high stiffness, and proper performance. One of the applications of composite laminates is fluid transmission by means of composite pipes. In this study, due to the increasing use of composite pipes, the effect of the main drilling parameters such as feed rate, rotational speed and tool diameter on the thrust force and temperature in the drilling of composite laminates with curvature was investigated and the results compared with one of composite laminates without curvature. To this end, glass fiber/epoxy composite laminates were manufactured by hand lay-up method. The experimental results show that, in general, in all diameters and feed rates, the thrust force in both composite laminates decrease with increasing rotational speed, but the effect of this parameter on temperature depends on the curvature of the composite laminates. Also, increasing the feed rate in both laminates increases the thrust force and decreases the temperature, and this is due to the increase of the pressure of the tool on the composite laminates and the reduction of the engagement time of the tool with the composite laminates, respectively. Finally, in general, the axial force and temperature in the same drilling parameters in the composite laminates with curvature is lower than that one without curvature.

Two points incremental forming is divided into two categories, negative and positive, and the process investigated in this research is Two points incremental forming. Today, in the forming industry, the production of parts with Dimensional accuracy and proper thickness distribution is very important. The aim of this research is to improve the dimensional accuracy and thickness distribution of the sample produced by the negative two-points incremental forming process. For this purpose, thickness distribution and dimensional accuracy of conical parts have been investigated by making changes in process parameters such as tool diameter, step down, type of lubricant and deformation strategy. To do this research, a numerically controlled milling machine, a complete set of negative die, St12 steel sheet with a thickness of 0.9 mm, spherical tool and SAE 10W oil lubricant were used The analysis of the results of the tests shows that due to the increase in the diameter of the tool at a constant step down, the minimum thickness increases from 0.24 to 0.5 mm, which has caused a decrease in thinning and ultimately the possibility of tearing in the sheet. Reducing the diameter of the tool in a constant step down has led to better shaping in the sharp corners of the production parts, and by applying a new shaping strategy and increasing the number of stages from one stage to two stages, the minimum thickness has increased. This state has improved the thickness distribution of the sample and reduced the possibility of tearing in the sample, and according to the investigations carried out in this research, the lubricant did not have a significant effect on the thickness distribution and dimensional accuracy of the production sample, and the use of the lubricant in this research only reduced the surface roughness.

In this paper, the parameters such as the diameter of the foam forming hollows, the thickness of the walls in the horizontal and vertical directions were investigated on the energy absorption of aluminum 356 closed cell foams produced by the lost foam casting method under low-speed impact. To reduce production costs and the number of tests, the test design method was used. Based on the design, 15 experiments were proposed. Then, according to the results of the experiment design, the simulation of the foams was done using Abaqus finite element software and based on the amount of absorption in different states, 4 foams were selected for the final production with two simple cubic structures and body center cubic. To perform the low-speed impact test, a 50 kg drop weight device that falls from a height of three meters was used. The results showed that the smaller the diameter of the foam holes, the higher the energy absorption. Also, the thickness of the foam walls in the horizontal direction has a greater effect on the energy absorption of the foam than in the vertical direction. Among the two types of structures studied, the simple cubic structure performed better than the body center cubic structure. Comparison of simulation and experimental results showed that the difference is between 10-30%. Most of this difference was related to the body center cubic structure feather, the main reason of which can be seen in the fact that it is more difficult to make these samples in reality compared to the ideal state of simulation.

Bone micromilling is widely used in orthopedic, spine, skull, knee joint replacement, and orthopedic surgeries to cut bone and make holes in tissue. The application of tools with a smaller diameter in the bone micromilling compared to conventional milling causes a significant reduction in force and also the length of the treatment period. In this article, in the form of an experimental study, an intelligent model for predicting bone micromilling force has been obtained based on the fuzzy inference system. For this purpose, first, an experiment design method has been used to extract a group of practical experiments. Then, based on the obtained results and approximation capability of fuzzy systems, an accurate model for predicting the cutting force has been established founded on the input values of tool rotation speed, feed rate, tool diameter, cutting depth and cutting direction. By examining the obtained results, it can be seen that the fuzzy model has been able to accurately approximate the resulting force of the bone micromilling process based on the considered inputs; The mean absolute percentage error and coefficient of determination for the data of the test section were calculated as 11.22% and 0.93%, respectively. Using the data of this research, surgeons with full knowledge can set the best values of the input variables of the micromilling process without worrying about causing damage and cracks in the bone tissue with the maximum possible operating speed.