• Journal of Computational Design and Engineering
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• 제3권3호
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• pp.266-273
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• 2016

Optimization of hole-making operations in manufacturing industry plays a vital role. Tool travel and tool switch planning are the two major issues in hole-making operations. Many industrial applications such as moulds, dies, engine block, automotive parts etc. requires machining of large number of holes. Large number of machining operations like drilling, enlargement or tapping/reaming are required to achieve the final size of individual hole, which gives rise to number of possible sequences to complete hole-making operations on the part depending upon the location of hole and tool sequence to be followed. It is necessary to find the optimal sequence of operations which minimizes the total processing cost of hole-making operations. In this work, therefore an attempt is made to reduce the total processing cost of hole-making operations by applying relatively new optimization algorithms known as shuffled frog leaping algorithm and proposed modified shuffled frog leaping algorithm for the determination of optimal sequence of hole-making operations. An industrial application example of ejector plate of injection mould is considered in this work to demonstrate the proposed approach. The obtained results by the shuffled frog leaping algorithm and proposed modified shuffled frog leaping algorithm are compared with each other. It is seen from the obtained results that the results of proposed modified shuffled frog leaping algorithm are superior to those obtained using shuffled frog leaping algorithm.

• 소성∙가공
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• 제17권6호
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• pp.412-419
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• 2008

Using lightweight materials in vehicle manufacturing in order to reduce energy consumption is one of the most effective approach to decrease pollutant emissions. As a lightweight material, magnesium is increasingly employed in automotive parts. However, because of its hexagonal closed-packed(HCP) crystal structure, in which only the basal plane can move, the magnesium alloy sheets show low ductility and formability at room temperature. Thus the press forming of magnesium alloy sheets has been performed at elevated temperature within range of $200^{\circ}C{\sim}250^{\circ}C$. Here we try the possibility of sheet metal forming at room temperature by adopting incremental forming technique with rotating tool, which is so called as rotational-incremental sheet forming(RISF). In this rotational-incremental sheet forming the spindle tool rotates on the surface of the sheet metal and moves incrementally with small pitch to fit the sheet metal on the desired shape. There are various variables defining the formability of sheet metals in the incremental forming such as speed of spindle, pitch size, lubricants, etc. In this study, we clarified the effects of spindle speed and pitch size upon formability of magnesium alloy sheets at room temperature. In case of 0.2, 0.3 and 0.4mm of pitch size with hemispherical rotating tool of 6.0mm radius, the maximum temperature at contact area between rotating tool and sheet metal were $119.2^{\circ}C,\;130.8^{\circ}C,\;and\;177.3^{\circ}C$. Also in case of 300, 500, and 700rpm of spindle speed, the maximum temperature at the contact area were $109.7^{\circ}C,\;130.8^{\circ}C\;and\;189.8^{\circ}C$.

• Advances in materials Research
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• 제1권2호
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• pp.129-146
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• 2012

Polycrystalline diamond is an ideal material for parts with micro-holes and has been widely used as dies and cutting tools in automotive, aerospace and woodworking industries due to its superior wear and corrosion resistance. In this research paper, the modeling and simultaneous optimization of multiple performance characteristics such as material removal rate and surface roughness of polycrystalline diamond (PCD) with ultrasonic machining process has been presented. The fuzzy logic and taguchi's quality loss function has been used. In recent years, fuzzy logic has been used in manufacturing engineering for modeling and monitoring. Also the effect of controllable machining parameters like type of abrasive slurry, their size and concentration, nature of tool material and the power rating of the machine has been determined by applying the single objective and multi-objective optimization techniques. The analysis of results has been done using the MATLAB 7.5 software and results obtained are validated by conducting the confirmation experiments. The results show the considerable improvement in S/N ratio as compared to initial cutting conditions. The surface roughness of machined surface has been measured by using the Perthometer (M4Pi, Mahr Germany).

• 한국공작기계학회논문집
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• 제14권2호
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• pp.83-90
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• 2005

A mirror cam mechanism a kind of conjugate cam mechanism consists of two cams, two rollers, and two links. Since profiles of two mirror cam are identical, a simultaneous machining of two cams is achievable. Some machining errors on cam profiles do not result in the internal acting force, which often causes problems in high speed cam mechanism between two links. Also, since angular accelerations of two links are same, the internal acting force by the difference of the angular accelerations does not occur in the mechanism. Thus the mirror cam mechanism is very useful in high speed machinery. This paper studies a design method as well as a machining method, and develops an exclusive CAD/CAM software for mirror cam profiles. The developed CAD/CAM software is applied to a typical mirror cam mechanism and a mock-up equipment is built in order to test the machinism mirror cm. Experimental investigations show that the contact between cam surface and roller surface according to cam rotation agrees well with the simulation on the developed CAD/CAM software.

• 한국공작기계학회논문집
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• 제16권2호
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• pp.57-62
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• 2007

The lubricational characteristics about friction wear has an effect on the material quality of surface. In this paper, we studied the lubricational characteristics through the surface modification experiment by spray coating the surface with $MoS_{2}$ and PTFE solid lubricants. In the case of $MoS_{2}$ and PTFE coating, the friction coefficient of Journal is lower than that for noncoating so the friction characteristics is excellent. In particular, the beginning characteristics of $MoS_{2}$ coating is excellent, and in the case of PTFE coating, seizure dose not appear seizure. $MoS_{2}$ and PTFE coating are excellent in the extreme pressure at high load. The wear characteristics is excellent in the following order; PTFE < $MoS_{2}$ < Non Coating. For Non coating, seizure appears at the beginning due to the heat, but in the case of $MoS_{2}$ and PTFE coating, it will have the excellent heat stability even at high temperature.

• 소성∙가공
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• 제10권3호
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• pp.193-199
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• 2001

Forming more than two parts of sheet metal in a single stamping operation lowers production costs, reduces weight, and heightens dimensional accuracy. The tailored blank (TB) is a laser-welded or mash-seam-welded sheet metal with different thicknesses, different strengths, or different coatings. Recently, automotive manufacturers have been interested in tailored blanks because of their desire to improve the rigidity, weight reduction, crash durability, and cost savings. Therefore the application to auto-bodies has increased. However, as tailored blanks do not behave like un-welded blanks in press forming operations, stamping engineers no longer rely on conventional forming techniques. Field try-outs are very important manufacturing processes for an economic die-making. In the field try-outs, the rounded geometries of tool and the drawbead shape and size in die face are generally modified when the forming defects can not be removed by the adjustment of forming process parameters. In this study, the field try-outs of tailored door inner panel are introduced and evaluated. The behaviours of laser tailored blank associated with different thickness combinations in the forming process of door inner panel are described focusing on terms of experimental investigations on the formability.

• 한국공작기계학회논문집
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• 제16권4호
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• pp.113-118
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• 2007

The flow forming has been used to produce long thin walled tube parts, with the reduced fanning force and the enhanced mechanical and surface quality for a good finished part, compared with the fanned parts using other method. Therefore, flow fanning technique is used widely in industrial production. Spinning and flow fanning techniques are used frequently in automotive, aerial and defense industries. The main factors for the flow fanning machine design are motor power, bed rigidity, mandrel stiffness, spindle power, roller profile, etc. Especially, mandrel, spindle power and roller are important factors for flow fanning machine capacity. In this paper, three dimensional finite element method for analysis of one-roller backward flow fanning of a workpiece has been carried out to study effects of roller profile on fanning force. Applied roller profile have roller lead geometries of angle $20^{\circ},\;30^{\circ},\;40^{\circ}$, concave and convex. Axial and radial fanning forces on various roller profiles are obtained and compared with each analysis cases.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1383-1388
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• 2015

Proportional integral derivative (PID) control is one of the conventional control strategies. Industrial PID control has many options, tools, and parameters for dealing with the wide spectrum of difficulties and opportunities in manufacturing plants. It has a simple control structure that is easy to understand and relatively easy to tune. Injection mold is warming up to the idea of cycling the tool surface temperature during the molding cycle rather than keeping it constant. This “heating and cooling” process has rapidly gained popularity abroad. However, it has discovered that raising the mold wall temperature above the resin’s glass-transition or crystalline melting temperature during the filling stage is followed by rapid cooling and improved product performance in applications from automotive to packaging to optics. In previous studies, optimization methods were mainly selected on the basis of the subjective experience. Appropriate techniques are necessary to optimize the cooling channels for the injection mold. In this study, a digital signal processor (DSP)-based PID control system is applied to injection molding machines. The main aim of this study is to optimize the control of the proposed structure, including a digital PID control method with a DSP chip in the injection molding machine.

• International Journal of Precision Engineering and Manufacturing
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• 제5권4호
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• pp.5-13
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• 2004

This study explains the effects of lubricant and surface treatment on the life of hot forging dies. The thermal load and thermal softening, that occur when there is contact between the hotter billet and the cooler dies in hot forging, cause wear, thermal cracking and fatigue, and plastic deformation. Because the cooling effect and low friction are essential to the long life of dies, the proper selection of lubricant and surface treatment is very important in hot forging process. The two main factors that decide friction and heat transfer conditions are lubricant and surface treatment, which are directly related to friction factor and surface heat transfer coefficient. Experiments were performed for obtaining the friction factors and the surface heat transfer coefficients in different lubricants and surface treatments. For lubrication, oil-base and water-base graphite lubricants were used, and ion-nitride and carbon-nitride were used as surface treatment conditions. The methods for estimating die service life that are suggested in this study were applied to a finisher die during the hot forging of an automobile part. The new techniques developed in this study for estimating die service life can be used to develop more feasible ways to improve die service life in the hot forging process.

• International Journal of Precision Engineering and Manufacturing
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• 제4권3호
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• pp.48-54
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• 2003

This paper deals with mirror grinding of a small-sized aspherical lens by a resin bonded diamond spherical wheel. Up to now, a spherical lens has been used for the lens of the optical communication optical part. However, recently, aspherical optical parts are mainly used in order to attempt the improvement in image quality and miniaturization of the optical device. It is possible to manufacture the aspherical lens which is presently being used in optical instrument through ultra-precision machining technology. Also, to realize compactness, efforts are being made to produce a micro aspherical lens, fur which the development of a high-precision, micro molding die is inevitable. Therefore, extensive research is being done on methods of producing a micro aspherical surface by high-precision grinding. In this paper, the spherical wheel was trued by cup-shaped truer and tool path was calculated by the radius of curvature of the wheel after truing and dressing. Then in the aspherical grinding experiment, WC material which is used as a melding die for the small-sized aspherical lens was ground. The results showed that a form accuracy of 0.1918 $\mu\textrm{m}$ P-V and a surface roughness of 0.064 $\mu\textrm{m}$ Rmax could be achieved.