• 한국기계가공학회지
• /
• 제5권3호
• /
• pp.65-70
• /
• 2006

The AWJM(Abrasive Water-jet Machining) technology is one of the cutting technologies, which can cut various materials with 2 or 3 times of the speed of sound. In this study, processing conditions such as jet-pressure, cutting speed, orifice diameter and stand-off distance, are used by following the design of experiments with 3 levels. Al6061 material which is normally applied on the field, is applied. Through the S/N ratio analysis with measured values, the optimization value of processing conditions to minimize the surface roughness and taper value is obtained. The order of significance is as follows; jet pressure, cutting speed, abrasive mixing ratio, orifice diameter and stand-off distance. RSM(Response Surface Method) is applied to find the optimal processing conditions to minimize both the surface roughness and the taper value by using jet pressure, cutting speed and abrasive mixing ratio.

• 한국기계가공학회지
• /
• 제12권2호
• /
• pp.20-26
• /
• 2013

This study focused on how it affects the surface roughness of work piece in cutting SCM415 steel, widely used steel in industry, by TiCN and TiN tools. Following conclusion was drawn from several experiments. The surface roughness of heat treated workpiece was better than that of non heat-treated materials. Moreover, the roughness of surface roughness(Ra 0.25) on feeding rate of 0.05 was better when it was in wet process, rather than dry process. As the feeding rate increases, TiCN coating tool shows better roughness of surface than TiN tool. Also, in heated treatment, TiCN coating tool shows the least straightness dimension deviation at feeding rate of 0.05, 0.15mm/rev, and concave-like R shape appears by the feeding rate orders of 0.05, 0.15, 0.1, 0.125 and 0.075mm/rev.

• 한국정밀공학회지
• /
• 제7권2호
• /
• pp.47-57
• /
• 1990

In-process recognition of the cutting states is one of the very important technologies to increase the reliability of mordern machining process. In this study, practical methods which use the dynamic component of the cutting force are proposed to recognize cutting states (i.e. chip formation, tool wear, surface roughness) in turning process. The signal processing method developed in this study is efficient to measure the maximum amplitude of the dynamic component of cutting force which is closely related to the chip breaking (cut-off frequency : 80-500 Hz) and the approximately natural frequency of cutting tool (5, 000-8, 000 Hz). It can be clarified that the monitoring of the maximum apmlitude in the dynamic component of the cutting force enables the state of chip formation which chips can be easily hancled and the inferiority state of the machined surface to be recognized. The microcomputer in-process tool wear monitor- ing system introduced in this paper can detect the determination of the time to change cutting tool.

• 한국생산제조학회지
• /
• 제20권5호
• /
• pp.535-540
• /
• 2011

It is well known that abrasive waterjet (AWJ) was developed as a kind of high-density energy processing technologies. AWJ is used to obtain cutting quality of various materials such as metal, ceramics, glass and composite materials within a short manufacturing time because of the characteristics of heatless and noncontact processing. However, surface roughness and dimension error like round, burr, taper vary severely according to the processing conditions such as pressure, cutting speed, orifice diameter, stand off distance and abrasive flow rate. In this paper, the effect of the shape of mixing chamber on surface quality is studied. Three types of mixing chamber - round, parabolic, elliptical - are suggested and each performance is compared to that of cylindrical mixing chamber experimentally. From the result, is proved to be the optimal mixing chamber in the aspect of surface quality the parabolic one.

• 소성∙가공
• /
• 제19권5호
• /
• pp.290-295
• /
• 2010

Shaving technology is one of the significant metal forming technologies which can make the smooth and fine sheared surface of products after shearing process. The sheared surface on the side wall of the cutting edge is very important because it functions as a basic surface for measuring the dimensions of product. Effective sheared surface after shaving can be influenced by several working variables such as shaving allowance, shaving clearance, type of material and profile of cutting edge. The influence of these variables on shaving characteristics was investigated in this study. A cut-off die to make the simplified gear-shaped products was manufactured. Three kinds of sheet metals (AL5052, SPCC and SAPH440) of 3mm thickness were firstly sheared and then shaved for four shaving allowances and three sharing clearances. It was shown through experiments that the optimum working condition to give the maximum effective sheared surface in shaving was found ; Shaving allowance is 0.2mm and Shaving clearance is 0.01mm.

• 한국기계가공학회지
• /
• 제15권1호
• /
• pp.26-33
• /
• 2016

In this study, a new method to develop a fixed diamond wire for silicon wafer machining by the multi-wire cutting method was developed. The new twist diamond wire has improved performance with high breaking strength and chip flutes structure. According to these characteristics, the new twist diamond wire can be used in the higher speed multi-wire cutting process with a long lifetime. Except the design of the new structure, the twist diamond wire is coating by electroless-electroplating process. It is good for reducing breakage and the falling-off of diamond grains. Based on the silicon material removal mechanism and performance of the wire-cutting machine, the optimal processing condition of the new twist diamond wire has been derived via mathematical analysis. At last, through the tensile testing and the machining experiments, the performance of the twist diamond wire has been obtained to achieve the development goals and exceed the single diamond wire.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
• /
• pp.85-90
• /
• 2001

Recent general Press brake has many problems in cutting high accurate products in the progress of industry. Previous hand-operated press brake needs many pre-processing works to adjust bending ang1e and marking-off works to calculate bending length. Also, the hand-operating work makes many geometric errors and has difficulty for variety-mass production. To solve these problems, this paper proposes Computer Numerical Control (CNC) general press brake and development of servo-control system based on database for reduction of geometric errors and pre-processing work time and high accuracy bending work.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.410-413
• /
• 1997

Recent general press brake has many problems in cutting high accurate products in the progress of industry. Previous hand-operated press brake needs many pre-processing works to adjust bending angle and marking-off works to calculate bending length. Also, The hand-operating work makes many geometric errors and has difficulty for variety-mass production. To solve these problems, this paper proposes Computer Numerical Control (CNC) general press brake and development of servo-control system based on database for reduction of geometric errors and pre-processing work time.

• 소성∙가공
• /
• 제14권3호
• /
• pp.257-262
• /
• 2005

In order to improve the quality of the sheared surface in cutting of inner structure bonded sheet metal the cut-off operation is mainly investigated, which is the typical shearing process in sheet metal forming technology. The sandwich sheet metals considered have inner structure which is constructed in the form of crimped expanded metal and woven metal. The inner structure is bonded between solid sheet by resistance welding or adhesive bonding. The shearing process is visualized by the computer vision system installed in front of the cut-off die and the sheared surface is measured and quantitatively compared with the help of the optical microscope after cut-off operation. From test results we found that the influence of sheared position can be observed and explained clearly and this result can be utilized to get the better sheared surface.

• 한국정밀공학회지
• /
• 제16권7호
• /
• pp.210-218
• /
• 1999

Sheet deposition type rapid prototyping system have many advantages : high build speed, low operating cost, large part size, no phase change, no need for support generation, and forth. However, those sheet deposition type rapid prototyping system require an additional post processing to remove excessive material attached to the part. This post processing is time consuming and labor intensive. Moreover, it is difficult for those system to fabricate parts with hollow cores and internal cavities. A new sheet deposition type rapid prototyping system that minimizes the post processing is proposed. The proposed system automatically removes excessive material in a peeling-off process between two cutting processes. In this way, the proposed system can reduce the post-processing time and cost as well as the limitation of the feasible geometric shapes in the conventional sheet deposition system.