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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 13, Issue 12 - Dec 1996
Volume 13, Issue 11 - Nov 1996
Volume 13, Issue 10 - Oct 1996
Volume 13, Issue 9 - Sep 1996
Volume 13, Issue 8 - Aug 1996
Volume 13, Issue 7 - Jul 1996
Volume 13, Issue 5 - May 1996
Volume 13, Issue 4 - Apr 1996
Volume 13, Issue 3 - Mar 1996
Volume 13, Issue 1 - Jan 1996
Selecting the target year
Machine Tool Technology; The Present and the Future(16)
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 9~23
Computer aided dynamic accuracy evaluation on CNC machine tools
H.D. Kwon ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 24~28
In this paper, a new measurement system has been developed for measuring servo errors of CNC machine tools. Unlike the ball link bar method using circular path, the developed system uses two orthogonal straight paths for measurement of errors, giving relatively short test length. For position measurment, linear displacement sensor and steel cube have been designed, and the software for relevant data sampling and error evaluation has been implemented.
A fundamental study on semi-solid forging with light and hardly formable materials
Park, J.C. ; H.Y. Cho ; Park, H.J. ; Park, J.U. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 29~35
For semi-solid forging with aluminuim alloys, it is required to develope the globular grain structure. It was studide that cold upsetting ration in SIMA process has effect on the globularization of grain structure. Globular microstructure was generated without cold upsettings for commercial aluminium alloys. In the case of A12024, the range of grain size was 40 .approx. 50 .mu. m. The grain growth in growth in globular microstructure depend on heating time. Spur gear was forged in semi-solid state to investigate the forging condition for A12024 with hydraulic press.
A Study on the Machinability Characteristics of ADI Materials for the Drilling Conditions
G.J. Cho ; E.C. Jeon ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 36~44
Drilling tests were carried out austempered ductile cast iron(ADI) to clarify the factors influencing the drilling characteristics of ADI material. The machinability of material was evaluated using high speed steel drill and cobalt contained drill of 6mm diameter. The spheroidal graphite cast iron materials were austemized at 900 .deg. C for 1 hour and then wear was kept at 375 .deg. C for 2 hours. Austempered ductile cast iron contains a great deal of retained austenite which contribustes to an improvement of impact strength. In this paper, machinability of ADI was invastigated by drilling experimentation. The results obtained are as follows:a) Flank wear incresses logarithmically with the increases of cutting time and proportionally with the increases of cutting force. b) Drilling hole number of about 2 times can be educed more step feed than ordinary feed due to the high hardness of ADI material and hardness increasing ascribed to the martensite of retained austenite.
A Study on the State-of-the-Art Technology Level Evaluation and Internation R&D Cooperation in the Field of Mechanical Engineering by Delphi Method
Y.J. Kwon ; S.H. Joo ; Kim, H.B. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 45~58
We provide a set of information on technologies in the area of mechanical engineering to draw meaningful action plans for the internationalization of National R&D activities. In this study, we employed a modified Delphi method to evaluate levels of our technoligical capabilities and developed countries' as well. We investigate technology acquistion methodologies, technology charcteristics and various aspects of interna- tional cooperation in terms of technology. Then, we analyzed final responses of participants(i.e., the third round results of Delphi method) to see the correlation among various factors in developing mechanical engineeing technologies through international cooperation. The technology classification used in this research was devel- oped by STEPI(Science and Technology Policy Institute). In conclusion, our mechanical engineering technology is investigated to be below the middle level stage of technology(i.e., the stage of digesting acquired technologies) except the shipbuilding equipments technology which is evaluated to be on the top level stage of technology.
Identification of Chip Form Using Pyrometer
Kweon, H.J. ; Paik, I.H. ; Sim, J.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 59~65
A major problem in automation of turning operations is the difficulty in obtaining a sufficient and reliable chip control. Therefore it becomes desirable to find a method which can detect the chip form. Newly born chips in usual metal cutting radiate infrared rays. When such chips run out of cutting point quickly, the radiated energy from the zone around the tool is low compared with that of the case when long tangled chips are staying around the tool. The difference in chip pattern can be detected from the output of pyrometer. But, strictly speaking, only the output of pyrometer does not identify the chip form because that is the removal of chip. Therefore, in this paper, a method of the identification of chip form using output of pyrometer and fuzzy inference is developed.
Optimal Topoloty Design of Structures and Ribs Using Density Distribution
J.P. Chung ; Lee, K.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 66~77
Optimal topology design is to search the optimal configuration of a structure which can be used as a shape at the conceptual design stage. Our objective is to maximize the stiffness of the structures and ribs under a material usage constraintl. The density of each finite element is the design variable and its relationship with Young's modulus is expressed by quadratic form. The configuration is represented by the entire density distribution, the structural analysis is performed by finite element method and the optimiza- tion is performed by Feasible Direction Method. Feasible Direction Method can handle various problems simultaneously, that is, mult-objectives and multi-constraints. Total computation time can be reduced by the quadratic relationship between the density and the material property and fewer design variables than Homogenization Method. Toplogy optimization technique developed in this research is applied to design the shapes of the ribs.
A Study on Desired Trajectory Tracking Control by Hydraulic Shovel Arms
S.D. Kang ; M.J. Huh ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 78~89
This paper discusses automation of a small-scale hydraulic shovel and its trajectory control. To move an end-effect (grinder) along a desired trajectory, the controller uses PID(proportional-integral- defferential) control and internal pressure of hydraulic cylinder. To apply PID control in the present hydraulic system, the system model is derived physically and its system parameters are obtained by actual measurement. To show the effectiveness of the PID controller and propriety of system model, the computer simulations and experiments are performed. These results of the simulations and experiments indicate that the PID trajectory control of robotic deburring by hydraulic shovel is very effective.
A Dynamic Modeling & State Sensitivity Analysis of the Surface Mounting Device
J.H. Jang ; C.S. Han ; J.D. KiM ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 90~99
In the area of assembly process of micro-chips and electronic parts on the printed circuit board, surface mounting device(SMD) is used as a fundamental tool. Generally speaking, the motion of the SMD is based on the ball screw system operated by any type of actuators. The ball screw system is a mechanical transformed which converts the mechanical rotational motion to the translational one. Also, this system could be considered as an efficient motion device against mechanical backlash and friction. Therefore a dynamic modeling and state sensitivity analysis of the ball screw system in SMD have to be done in the initial design stage. In this paper, a simple mathematical dynamic model for this system and the sensit- ivity analysis are mentioned. Especially, the bond graph approach is used for graphical modeling of the dynamic system before analysis stage. And the direct differentiation method is used for the state sensit- ivity analysis of the system. Finally, some trends for the state variables with respect to the design variables could be suggested for the better design and faster operating based on the results of dynamic and state sensitivity.
Sheet Modeling and Transformation of Sheet into Solid Based on Non-manifold Topological Representation
Lee, S.H. ; Lee, K.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 100~114
In order to create a solid model more efficiently for a plastic or sheet metal product with a thin and constant thickness, various methods have been proposed up to now. One of the most typical approaches is to create a sheet model initially and then transform it into a solid model automatically for a given thickness. The sheet model as well as the transitive model in sheet modeling procedure is a non-manifold model. However, the previous methods adopted the boundary representations for a solid model as their topological framework. Thus, it is difficult to represent the exact adjacency relationship between topological entities and to implement the topological operations for sheet modeling and the transformation procedure of a sheet into a solid. In this paper, we proposed a sheet modeling system based on a non-manifold topological representation which can represent solids, sheets, wireframes, and their mixture. A set of generalized Euler operators for non-manifold topology as well as the sheet modeling capabilities including adding, bending, and punching functions are provided for easy modeling of sheet objects, and they are perfomed interactively with a two dimensional curve editor. Once a sheet model is completed, it can be transformed into a solid automatically. The transformation procedure is composed of the offset functions and the Boolean operations of sheet models, and it is even more comprehensive and easier to be implemented than the precious methods.
High Precision Position Synchronous Control in a Multi-Axes Driving System
J.H. Byun ; S.K. Jeong ; J.H. Yang ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 115~121
Multi-axes driving system is more suitable for FMS(Flexible Manufacturing System) compared with a conventional single-azis driving system. It has some merits such as flexibility in operation, improvement of net working rate, maintenance free because of no gear train, etc. However, studies on position synchronous control for high precision in the multi-axes driving system are not enough. In this paper, a new method of position synchronous control is suggested in order to apply to the multi- axes driving system. The proposed method is structured very simply using speed and position controller based on PID control law. Especially, the position controller is designed to keep position error to minimize by controlling either speed of two motors. The effectiveness of the proposed method is successfully confirmed through several experiments.
Interval Analysis for Assemblability Checking between Variational Parts : Part 2
Park, S.H. ; Lee, K.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 122~132
It can be expected that the tolerances of the parts are assigned systematically and thus the parts are designed considering the assemblability in advance in the design stage, if the tolerances can be stored together with the geometric model of the parts and the assemblability of the parts is verified in the computer. In other words, an example of the concurrent engineering is realized. To verify the concepts described above, a new method is proposed to verify the assemblability when the tolerance information and the geometric model of the parts of an assembly are given. This method determines the assemblability by subdividing the range of relative motion between parts until the subdivided region corresponding to free of interference can be found.
Design of Unknown-Input PI Observer and Realization of Exact LTR
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 133~139
The Optimization of a Hydrostatic Spindle System for Grinding Machines
Lee, C.H. ; Park, C.H. ; Lee, H.S. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 140~147
Machining accuracy of machine tools spindles using the hydrostatic bearing, largely depends on the static stiffness and the thermal deformation of the spindle unit. In this paper, the modelling and static, thermal analysis of the hydrostatic spindles were performed for the relationship between the design variables like the bearing span, overhang, bearing stiffness and static stiffness at spindle. The goal of optimization is the mazimum, static stiffness at spindle nose with lower temperature rise in hydrostatic bearing. Temperature rise of hydrostatic bearing is minimized with the variables of spindle diameter and oil supply pressure. Finally, validity of the proposed algorithm is verified by improving the static, thermal performance of the existing hydrostatic spindles.
Stress Intensity Factors for the Mixed Mode in Rotating Disks by Boundary Element Method
Park, S.O. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 148~157
This paper deals with the applicability of linear elastic fracture mechanics under centrifugal force. Stress intensity factors K are calculated as a function of the inclination crack of length 2a, the position at different angular velocities 1200rpm, 2400rpm and at different values of the inclination crack angle .phi. ( .phi. = 0 .deg. , 15 .deg. , 30 .deg. , 45 .deg. , 60 .deg. , 75 .deg. , 90 .deg. ) and are measured in models of rotation disks using a boundary element method. Especially, stress intensity factors
obtained separately from the crack tip of the mixed mode, were used to further investigate the influence of
on fracture in rotating disks. With the increase in the speed of rotation, the effect of K/ sub l/became larger where as that of
became small. For the increase in the inclination crack angle .phi. , a decrease in
and an increase in
A Study on the Flat Surface Generation Using Flexible Disk Grinding
S.M. Yoo ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 158~166
In this study, a flexible disk grinding process is applied in order to produce high precision product. A new model was developed considering feed motion along horizontal and vertical direction. Different types of feed speed variation was tested with respect to distinct process stages in order to achieve flat surface. It was observed that highest order polynomial form for both horizontal and vertical feed speed variation among the proposed categories produced surface close to flat one. Disk deflection trend during the process was visualized confirming the proposed scheme. Cutting force and VRR(volume removal rate) was observed as an aid to process planning.
A Study on the Texturing Characteristics of Work Roll and Variation of Strip Surface Roughness in 4-Hi Mill
Kim, M.K. ; E.C. Jeon ; Kim, S.K. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 7, 1996, Pages 167~175
Work roll wear in the cold rolling of steel strip is strongly affected by rolling materials, rolling conditions and lubrication. Tests were performed to find the effects of rolling materials under the same lubricating conditions. Surface roughness of cold rolled steel strip as well as the coating technique itself is quite improtant in obtaining high image clarity of electronic products and car outer panels. Therefore this paper reviews for improvement of roughness and peak count about the surface of Cr coated work roll is investigated from the actual temper mill. The conclusions were obtained as follows; 1) Work roll wear in the cold rolling of steel strip is strongly affected by carbon contents of rolling materials, but there is not a separating force and total reduction ratio. 2) The roughness of strip surface is larger in the direction of width than in roll direction. 3) The electro-discharge textured roll has more uniform roughness distribu- tion than shot blasted roll and it's life time is two times longer than shot blasted because it has more harmonic wave roughness, and the higher peak count of surface roughness. 4) The life time of Cr coated work roll is 2 times longer than that of shot blasted work roll and variation of peak count, roughness and life time of Cr coated work roll is similar to electro-discharge texturing work roll. 5) The proper Cr coating thickness is 10 .mu. m at the work roll of temper mill.