h. baseri

In this research, a hybrid method of a simple shear extrusion (SSE) process is proposed with simultaneous application of ultrasonic vibrations at the beginning of the deformation zone in pure copper. A cylindrical-conical-cylindrical horn was designed to amplify and transmit the ultrasonic vibrations using modal analysis in Abaqus. The resonant frequency of 20.332 kHz was used with two amplitudes of 15 and 25 micrometers. Then, the produced ultra-fine grain copper samples after the first pass with and without ultrasonic vibrations were compared. A 54% and 65% reduction in grain size were reported in ultrasonic-assisted simple shear extrusion (USSE) with two amplitudes of 15 μm and 25 μm, respectively. Also, a significant increase in microhardness values in the USSE method compared to the SSE method indicated that the hardness increases significantly by increasing the amplitudes under the influence of acoustic hardening. In addition, the required force to extrude the samples with the presence of ultrasound was reduced under the effect of acoustic softening. In addition, finite element simulation of both SSE and USSE processes was performed in Abaqus/Explicit software. Higher equivalent plastic strain and plastic deformation along the length of the sample were reported in the USSE method. Additionally, in the USSE method compared to the SSE method, the maximum plastic strain distribution was improved by applying ultrasonic vibrations.

Tool geometry has a significant impact on cutting mechanics and key machining parameters such as tool life, workpiece surface quality, specific cutting energy, and dynamic stability of the cutting process. In the turning process, where the cutting tool remains in a fixed position, it is possible to develop a mechanism to adjust the tool angles during machining. This research introduces a new tool-holder mechanism for the lathe that can adjust the side inclination and front inclination angles. The simultaneous control of these angles allows for precise adjustment of the normal rake and clearance angles of the tool. Since these angles greatly affect all machining parameters, this mechanism can enhance the quality of the machining process. By implementing an active chatter control system using the proposed mechanism, the controller can reduce the tool’s clearance angle to increase process damping and prevent chatter. The mechanism enables adjustment of the normal rake and clearance angles by up to 8 degrees. Test results demonstrate that utilizing this mechanism and the provided chatter suppression/control technique can effectively prevent chatter at higher machining speeds and improve machining stability. The proposed mechanism has potential applications in advanced CNC lathes with open architecture for precise and optimal adjustment of machining parameters.

Blow molding is one of the most widely used processes for producing hollow plastic parts. In this process, the wall thickness uniformity of blow molded part is a prime concern. Processing parameters such as blowing pressure, melting temperature, and parison thickness affect the uniformity. In this paper, extrusion blow molding process for Peugeot 405 and Peugeot Pars water tanks has been studied by simulations and experiments. The effects of parison thickness in three levels and blowing pressure in two levels were investigated on the wall thickness of blow molded part. Parison thickness was varied by manipulating air gap between mandrel and die. The results indicated that the increase of blowing pressure had no effect on the part thickness. However, the parison thickness significantly influenced the thickness of molded part. Parison thickness was optimized by considering the weight and required strength of the part, so that, the material consumed was decreased. Also, Polyflow software was used to simulate the blow molding process. For this purpose, the initial parison geometry was experimentally determined by a measurement set-up, then the inflation process was simulated on this real parison. A good agreement was obtained between thicknesses of part in the experiments and simulations.

In this paper operating parameters that used by various researchers for supercritical fluid extraction of pharmaceutical agents from six various types of pharmaceutical plants were studied. Materials that studied here have many applications in the pharmaceutical, food and cosmetic industries and nowadays we see an increasing demand for replacing of these materials by synthetic materials. In this work, effects of various parameters such as temperatures and pressures of extraction fluid, extraction time, mean particle size of powders and other effective parameters on the yield of extraction and composition of extract were reviewed. And optimum conditions for the best composition of extract and highest yield of extraction were reported.