فهرست مطالب

Journal of Modern Processes in Manufacturing and Production
Volume:4 Issue: 1, Winter 2015

  • تاریخ انتشار: 1393/12/27
  • تعداد عناوین: 6
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  • Majid Molaie Pages 5-18
    Using of colloids and polymeric microparticles are gradually increasing. It is observed that the positive effects of particles stems in both traditional applications such as column pickings, coatings and paints to more recent technologies in diagnostics, drug delivery and optical devices are well documented. This review focuses on importance of colloids and covers their applications on three level: (1) The cell/tissue level; (2) The single device level; (3) Selfassembly. Then I state the working principles and developments in fabrication methods. Key advantages and challenges of colloids and polymeric microparticles are discussed as well. Papers reviewed in this study show that while there are practical methods to the synthesis of such particles but accurate control of anisotropy and morphology that is essential for specialized particles is a critical problem. Therefore, a new approach is desired, which generates geometrically and chemically anisotropic particles with high throughput. In addition, this approach should be able to generate particles with complex composition, and preferably have adaptability.
    Keywords: Colloid, Polymeric microparticles, Single device, Cell, Tissue, Self, assembly
  • Hassan Gheisari, Ebrahim Karamian Pages 19-28
    Manufactured single crystal components using Ni-base super alloys are routinely used in the hot sections of aero engines and industrial gas turbines due to their outstanding high temperature strength, toughness and resistance to degradation in corrosive and oxidative environments. To control the quality of the single crystal turbine blades, particular attention has been paid to grain selection, which is used to obtain the single crystal morphology from a plethora of columnar grains. For this purpose, different designs of grain selectors are employed and the most common type is the spiral grain selector. A typical spiral grain selector includes a starter block and a spiral (helix) located above. It has been found that the grains with orientation well aligned to the thermal gradient survive in the starter block by competitive grain growth while the selection of the single crystal grain occurs in the spiral part. In the present study, 2Dspiral selectors with different geometries were designed and produced using a state-of-the-art Bridgeman Directional Solidification casting furnace to investigate the competitive growth during grain selection in 2d grain selectors. The principal advantage of using a 2-Dselector is to facilitate the wax injection process in investment casting by enabling significant degree of automation. The directional solidification process for obtaining single crystal component for Nickel Super alloys based on the competitive growth in 2D and 3D single crystal grain selector was experimentally investigated for various geometries. Transverse sections of the grain selectors using optical and EBSD microscopy techniques were observed to understand the competitive grain growth process.
    Keywords: Grain Selector, Single Crystal, Directional Solidification, CMSX, 4 Super alloys, Investment Casting
  • Morteza Sadegh Amalnik Pages 29-44
    Wire electrical discharge machining (WEDM) is a method to cut conductive materials with a thin electrode that follows a programmed path. The electrode is a thin wire. Typical diameters range from. 004" -. 012" (.10mm -. 30mm) although smaller and larger diameters are available. WEDM is a thermal machining process capable of accurately machining parts with varying hardness or complex shapes. WEDM process is based on electrical discharge machining (EDM) sparking phenomenon, utilizing the widely accepted non-contact technique of material removal. The hardness of the work piece material has no detrimental effect on the cutting speed. There is no physical contact between the wire and the part being machined. Rather, the wire is charged to a voltage very rapidly. This wire is surrounded by deionized water. When the voltage reaches the correct level, a spark jumps the gap and melts a small portion of the work piece. The deionized water cools and flushes away the small particles from the gap. This paper addresses the concept of WEDM and its parameters and development of an intelligent knowledge based system (IKBS) for WEDM in computer based concurrent engineering environment. The system links with a feature based CAD system in order to extract design data. The system is linked with databases. The machining cycle time, cost, material removal rate, and surface roughness of hole making are estimated for each selected design feature. The system provides useful information for product designers and manufacturing engineers and also advises manufacturing engineers to select optimum machining parameters.
    Keywords: Knowledge based system, wire electrical discharge machining, optimization
  • Masoud Feizi, Reza Jafari Nedoushan Pages 45-56
    Metal forming processes, compared with machining ones, reduce production steps and increase manufacturing speed in addition to saving raw material. In this paper, forming process of column of a steering mechanism is investigated by finite element analyses and experimental tests; and optimum die design parameters are found. Forming process parameters including die opening angle, bearing length, clearance between work piece, die and friction coefficient were studied. Some new ideas were also used in manufacturing process of dies with compression tube forming process. Without using an appropriate lubricant, friction coefficient between die, tube, the probability of tube distortion and tube bulging increased significantly. The forming force is also strictly dependent on friction coefficient and it also increases with increasing bearing length of the die. The manufactured sample had good agreement with the original drawing of profile appearance and dimensions. Effects of die and tube clearance on the required force and final part surface quality are also investigated.
    Keywords: Steering column, Finite element analyses, Cold extrusion
  • Ali Rahmani, Ali Mirmohammadi, Seyed Mohammad Javad Zeidi, Saeed Shojaei Pages 57-64
    Initially, the first aim of the present study is to model 3-axle rigid truck by developing a code in Matlab. Secondly, each equation should be drived by acquisition of Lagrange approach.After deriving equations successfully, validation is performed by some result which was mentioned in Bohao Li's master thesis. Although the present approach is totally different from the approach that Boahao Li used in his analysis but the deviation of the present results from that thesis on average is 7 percent which shows an acceptable accuracy in our current numerical approach. In the present study 19 degree of freedoms is used for determining natural frequency and dominant motions. By having dominant motion, it is possible to clarify which region is in endangering of resonance. This paper presents a portion of the results that have been gathered and for watching new result in this field, it is recommended to read our future papers. Solidworks CAD software is also used to calculate mass properties of several components that used in our present study.
    Keywords: Natural frequencies, mode shapes, Lagrange method, Multi, axles truck
  • Moslem Ahmadi, Mohammad Hojaji, Saeed Toolani Pages 65-81
    The study of interactions of jet into cross flow at different longitudinal and transverse angles of jet was studied. The following components were designed and constructed: a low velocity wind tunnel to produce the uniform flow, a flat plate with a traverse injection system to simulate the jet injection, and a spatial rake to measure the total pressure. The tests were carried out at longitudinal (α) and transverse angles (β) of 60, 75, and 90 degrees and a velocity ratio of 2.5. The free stream and jet stream velocities were set at 20 and 50 meters per second and were constant for all the tests. Results showed that flow field development could be controlled through injecting oblique jets. Decreasing β caused the following
    Results
    1) improved the effects of injection along the mixing direction, 2) increased jet penetration along the plate width direction, and 3) increased the flow wake. In addition, decreasing α led to a slight increase downstream of the nozzle, but failed to produce a significant change in to total pressure coefficient.
    Keywords: Wind tunnel design, Injection simulator, Jet in cross flow, Jet (injection) angle