• 한국정밀공학회지
• /
• 제14권3호
• /
• pp.57-65
• /
• 1997

In this study, a cutting force in the Ball-end milling process is calculated using Z-map. Z-map can describe any type of cutting area resulting from the previous cutting geometry and cutting condition. Cutting edge of a ball-end mill is divided into infinitesimal cutting edge elements and the position of the ele- ment is projected to the cutter plane normal to the Z axis. Also the cutting area in the cutter plane is obtained by using the Z-map. Comparing this projected position with cutting area, it can be determined whether it engages in the cutting. The cutting force can be calculated by numerical integration of cutting force acting on the engaged cutting edge elements. A series of experiments such as contouring and upward/downward ramp cutting was performed to verify the calculated cutting force.

• 한국CDE학회논문집
• /
• 제3권3호
• /
• pp.161-167
• /
• 1998

Cutting forces in ball-end milling of slanted surfaces are calculated. The cutting area is determined from the Z-map of the surface geometry and current cutter location. The obtained cutting area is projected onto the cutter plane normal to the Z-axis and compared with cutting edge element location. Cutting force is calculated by integration of elemental cutting forces of engaged cutting edge elements. Experiments with various slanted angles were performed to verify the proposed cutting force estimation model. It is shown that the proposed method predicts cutting force effectively for any geometry including sculptured surfaces with cusp marks and surfaces with pockets and holes.

• Journal of Biosystems Engineering
• /
• 제20권1호
• /
• pp.13-21
• /
• 1995

This study was conducted to investigate the cutting mechanism of reciprocating knife of combine harvester. The cutting operation of reciprocating knife with the arrangement of the low-cutting and the double-cutting was demonstrated through cutting pattern diagram which was drawn by computer graphics. Various kinds and dimensions of reciprocating knives were analyzed using the developed program. The results are summarized as follows (1) The low-cutting type reciprocating knife was represented similar cutting characteristics to the standard type, but the maximum stalk-deflection was decreased as 1/2 level of the standard type. And the first ledger plate should be designed shorter than the second ledger plate. (2) The bunching area and the maximum stalk-deflection for the double cutting knife almost were not changed since cutting velocity ratio of 0.6, but the secondary cut were occurred at ratio of 0.8 and increased rapidly over these ratio. (3) The double cutting knife was recommended for the high speed combine, because its bunching area and the maximum stalk-deflection were decreased as 1/2 level of the standard type. (4) In order to maintain the proper cutting mechanism characterized by the bunching area, the maximum stalk-deflection and the secondary cutting length etc., the adequate cutting velocity at forward speed of 0.5㎧ to 1.2㎧ was from 0.3㎧ to 0.96㎧ for the double cutting knives.

• Journal of Biosystems Engineering
• /
• 제20권1호
• /
• pp.3-12
• /
• 1995

This study was conducted to investigate the cutting mechanism of the reciprocating knife of combine harvester. The cutting operation of reciprocating knife was demonstrated through the cutting pattern diagram which was drawn by computer graphics. Various kinds and dimensions of standard-type reciprocating knives were analyzed by the developed program. The results are summarized as follows : (1) For the 50mm standard reciprocating knife, the bunching area and the maximum stalk-deflection were decreased rapidly according to the increase of cutting velocity ratio by 1.0 and decreased very slowly over this ratio. But, the secondary cut was occurred at ratio of 1.0 and increased rapidly over this ratio. (2) The 76mm standard knife showed better cutting mechanism than the 50mm, in two respects : the larger cutting area per one stroke and the lower revolutional speed of crank shaft for the same cutting velocity. (3) In respect to the bunching area and the secondary cutting length, the adequate height of 50mm standard reciprocating knife was 45~50mm. (4) In order to maintain the proper cutting mechanism, the adequate cutting velocity at forward speed of 0.5㎧ to 1.2m/s was from 0.4m/s to 1.2m/s for the standard knife.

• 한국공작기계학회논문집
• /
• 제15권1호
• /
• pp.17-22
• /
• 2006

Zirconium is widely applied in industrial area. In this study, the exeperiments are performed to investigate the differences in cutting characteristics of zirconium coated material which deposited on cutting tool using physical vapor deposition(PVD). For comparison, TiN coated tool is used to compare with zirconium coated tool. Experimental results were compared for tool wear, surface roughness and cutting force. The tool wear of PVD coated bites is affected by the various cutting conditions. This new stuff 'zirconium coated tool' wears $33\%$ less and improves surface roughness $23\%$ more in various cutting conditions. Cutting force is analyzed by using various workpiece, and the research strongly confirms that 'zirconium' remains better condition than 'titanium'. As a result 'zirconium' coated tool can be performed far better than 'titanium' coated tool on metal cutting.

• 한국정밀공학회지
• /
• 제15권12호
• /
• pp.212-219
• /
• 1998

During machining of dies and molds with sculptured surfaces. the cutter contact area changes continuously and results in cutting force variation. In order to implement cutting force prediction model into a CAM system, an effective and fast method is necessary. In this paper. a new method is proposed to predict mean cutting force. The cutter contact area in the spherical part of the cutter is obtained using Z-map, and expressed by the grids on the cutter plane orthogonal to the cutter axis. New empirical cutting parameters were defined to describe the cutting force in the spherical part of cutter. Before the mean cutting force calculation, the cutting force density in each grid is calculated and saved to force map on the cutter plane. The mean cutting force in an arbitrary cutter contact area can be easily calculated by summing up the cutting force density of the engaged grid of the force map. The proposed method was verifed through the slotting and slanted surface machining with various inclination angles. It was shown that the mean force can be calculated fast and effectively through the proposed method for any geometry including sculptured surfaces with cusp marks and holes.

• 한국기계가공학회지
• /
• 제11권4호
• /
• pp.67-71
• /
• 2012

The purpose of this study is to investigate cutting characteristics and wear behavior in FCD500 ductile cast iron turning with different cutting tools, tungsten-carbide and CBN. Mechanical property, cutting characteristics and the application to the real industrial area is the final purpose. FDC500 ductile cast iron is now widely used in the various commercial vehicle parts for increased machine abilities which accrue more tensile strength with lower hardness. Several studies have been fulfilled for the material and heat-treatment area, but few with the cutting characteristics and wear behavior in the turning area.

• 한국안전학회지
• /
• 제8권4호
• /
• pp.73-81
• /
• 1993

In recent years, mould industry in machining requires to increase machining productivity and to reduce costs, To adapt this trend it is necessary to optimize machine condition, Even though many researches in this area introduced various way to set the optimal condition, still there are not enough. Therefore this research was done to select the optimal cutting condition for industry, and to develop the computer program to select the optimal cutting condition automatically. The result of this research will contribute to increase machining productivity of various mould companies with the automatic selection of optimal cutting condition.

• 한국초지조사료학회지
• /
• 제13권3호
• /
• pp.203-212
• /
• 1993

This experiments were carried out to estimate the optimum final cutting date in autumn and the selection of highly adaptable varieties in mountainous pastures of Taekwalyong area. The evaluations were based on the data of varietal differences of dry weight of plant(DW) and yield components of the 1st cutting as affected by various final cutting dates of last autumn. Nine varieties of tall fescue Barvetia, Fuego. Demeter, Safe. Barcel, Forager, Johnstone, Enforcer and Stef. were used and 4 final cutting date of autumn were $C_1$, cut on 30 Sept. $C_2$, on 14 Oct. $C_3$, on 28 Oct. and $C_4$. on 11 Nov.. respectively. The results obtained were as follows: I . Between the dry weight of plant(DM) and yield components of 1st cutting were different by various final cutting dates of autumn. The dry weight of plant(DW) was significantly positive correlated with heading characteristics of the 1st cutting in earlier cuttings($C_1- C_3$) of autumn, but there was not significant correlated with heading characteristics of the 1st cutting in the latest cutting($C_4$) of autumn. 2. The variety of Forager with heavier weight of heading tiller(HTW) and dry weight of tiller(WT) showed the highest dry weight of plant(DW) of the 1st cutting in earlier cuttings($C_1-C_3$) of autumn, whereas the variety of Barcel with high number of tillers per plant(NT) showed a high dry weight of plant(DW) of the 1st cutting in the latest cutting($C_4$) of autumn. 3. Optimum final cutting date and critical period of mountainous pastures in Taekwalyong area were estimated in late September($C_1$) and middle October($C_2$), sespectirety. 4. The dry weight of plant(DW) of the 1st cutting was significantly negative correlated with final cutting dates in growth period of autumn.

• 대한기계학회논문집A
• /
• 제37권10호
• /
• pp.1269-1278
• /
• 2013

엔드밀링 공정은 형상창성기구의 특성 상, 절삭면적의 주기적인 변화를 피할 수 없다. 그러므로, 본 연구에서는, 가공 중 절삭날과 공작물 사이의 간섭영역에 해당하는 절삭면적의 모델을 확립하여, 가공면 형상 특성과 절삭면적의 관계를 규명하고자 한다. 대상 가공면은 측벽을 선정하였으며, 형상 특성은 축 방향 진직도를 선택하였다. 절삭면적 및 축방향 진직도에 영향을 미치는 특이점 추정 모델의 타당성은 반경 방향 및 축 방향 절삭깊이를 변화시키며 엔드밀링 가공을 수행하여 검증하였다. 연구 결과, 배분력이 음의 값을 갖지 않는 안정적인 엔드밀링 가공의 경우, 상향절삭은 절삭면적이 증가했다. 일정해지는 영역에서, 하향절삭은 절삭면적이 일정했다 감소하는 영역에서 가공면을 창성하며, 영역이 변화될 때 가공면에 특이점이 발생하는 것이 확인되었다.