• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.121-127
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• 2008

Nowdays CAE has been used for almost all injection molding designs in order to find the best injection conditions. Almost all CAE use 2-D mesh, but the CAE with 2-D mesh can't indicate such as jetting, flow-mark and filling imbalance in multi cavity mold. In this study, we suggested a new 3D meshing. the method which can indicate the filling imbalance in geometrically balanced runner system with Mold Flow MPI 6.1 and we found out that the calculation times are saved. As a feasibility study, we verified that Melt Flipper, RC Pin etc appeared the balanced filling behaviors. of geometrically balanced runner system and Melt Flipper, filling imbalance was indicated more accurately.

• 소성∙가공
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• 제24권5호
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• pp.340-347
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• 2015

Multi-pass shape drawing is used to manufacture long products of arbitrary cross-sectional shapes. This process allows smooth surface finishes and closely controlled dimensions of the cross-sectional shape. Tube shape drawing for hollow type products provides material savings and weight reduction. The intermediate die shapes are very important in multi-pass tube shape drawing. In the current paper, the design method for the intermediate dies in a tube shape drawing process is developed using a die offset for corner filling (DOCF) method. Underfill defects are related to the radial velocity distribution of each divided section in the deformation zone. The developed intermediate die shape design was applied to the two-pass tube shape drawing with fixed mandrel for manufacturing a hollow linear motion (LM) guide rail. The proposed design method led to uniform and steady metal flow at each divided section. FE-simulations and experiments were conducted to validate the effectiveness of the proposed method in multi-pass tube shape drawing process.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2610-2618
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• 2000

In this paper, the elastic deformation of cold forging die has been investigated to improve the accuracy of forged parts with FEM analysis and experiments using the strain gages. In the finite element analysis, two types of analysis are used to predict elastic deformation of die. The one is that dies are considered to be elastic body from initial stage to final one, and the other is that the dies are considered to be rigid body during forging simulation and then considered to be elastic body at elastic analysis. Considering the results of analysis and experiments, it is likely that the analytical results are in good agreement with experimental inspections. The method using the elastic assumption of die relatively takes a lot of time to simulate the forming operation. However, It is better that using an elastic die to predict not only the shape of product but also filling of die cavity.

• 한국산학기술학회논문지
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• 제20권7호
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• pp.347-352
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• 2019

본 연구는 소형 유도전동기 회전자를 생산공장에서 금형주조(die casting)로 제작 시 발생하는 cast 부 품질문제를 개선하기 위하여 수행되었다. 1차 연구결과와 현장 적용성을 고려한 수많은 parametric study를 통하여 새로운 rotor core cast model을 제안하였으며, 그 제안된 model에 대한 유효성을 평가, 검증하기 위하여 주조해석 전용프로그램을 사용한 수치해석과 실제품에 대한 현장실험을 통하여 다음과 같은 결론을 얻었다. 첫째, 유도전동기 회전자의 새로운 cast model에 대한 충진해석을 수행한 결과 용탕은 하부 end ring 부를 먼저 충진하고 이동하여 상부 end ring, core slot 부분을 충진하고 최종적으로 core slot 부분에서 충진이 완료된다. 둘째, 새롭게 제안된 rotor core cast model에 대한 용탕의 유동 양상을 보면 하부 end ring 부에 용탕의 유동에 의한 와류가 적게 발생하였으며, 현장실험 결과 하부 end ring 부 단면에서 소량의 작은 결함만이 발견되었다. 셋째, 유도전동기 회전자 제작 시 rotor core cast 형상 변경을 통하여 end ring 부 결함 발생 면적이 약 70 % 감소한 양호한 품질의 회전자를 생산할 수 있다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 추계학술대회 논문집
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• pp.133-140
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• 1994

In this paper, we have proposed a new method to determine the initial billet for the forged products using a function approximation in neural networks. the architecture of neural network is a three-layer neural network and the back propagation algorithm is employed to train the network. By utilizing the ability of function approximation of neural network, an optimal billet is determined by applying nonlinear mathematical relationship between shape ratio in the initial billet and the final products. A volume of incomplete filling in the die is measured by the rigid-plastic finite element method. The neural network is trained with the initial billet shape ratio and that of the un-filled volume. After learning, the system is able to predict the filling region which are exactly the same or slightly different to results of finite element method. It is found that the prediction of the filling shape ratio region can be made successfully and the finite element method results are represented better by the neural network.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.205-209
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• 1998

Unlike the drawing of round section from round bar, the shaped drawing like polygonal section is known to have influence not only drawing stress but also comer filling. Therefore, this study analyze the drawing process of suqare rod from round bar using nonsteady state rigid-plastic FEM. To investigate effects of process variables of the drawing process of square rod from round bar, FE-simulations with variety of reduction in area and semi-die angle for a given frictional condition have been conduction. By this results, it has to suggest optimal process condition on the drawing stress and the comer filling. In addition, it has determined forming limit considering necking and bulging.

• 한국정밀공학회지
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• 제15권11호
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• pp.145-151
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• 1998

Unlike the drawing of round section from round bar, the shaped drawing like polygonal section is known to have influence not only drawing stress but also corner filling. Therefore. this study analyze the drawing process of suqare rod from round bar using nonsteady state rigid-plastic FEM. To investigate effects of process variables of the drawing process of square rod from round bar, FE-simulations with variety of reduction in area and semi-die angle for a given frictional condition have been conducted. By this results, it has to suggest optimal process condition on the drawing stress and the corner filling. In addition, it has determined forming limit considering necking and bulging.

• Design & Manufacturing
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• 제17권4호
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• pp.57-62
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• 2023

As a representative method for mass production, a multi-cavity type mold capable of simultaneously molding products of the same shape can be applied. It has the advantage of improving the productivity from several times to several tens of times, but it may cause disadvantages which is the quality deviation with each cavity. This study, therefore, has tried to increase the cavity filling balance by using a melt flipper and a flow distance control part in the runner part of the mold. Along with this, the design and manufacturing of air vents during injection molding have been verified through experimental methods to achieve a higher level of multi-cavity filling balance and dimensional accuracy.

• 소성∙가공
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• 제19권5호
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• pp.283-289
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• 2010

Extrusion process in the bulk material for fabrication of miniature helical gears has problems such as a high forming load and short tool life because the cross-section is complex and asymmetry. To overcome these problems, in this study, miniature helical gears were fabricated by Zn-22Al powder hot extrusion. The included die angle for minimum extrusion load and improving die filling was determined by FE-simulation. The Zn-22Al spheroidal powder produced by gasatomization were compacted and sintered for extrusion experiment. The dimension of helical-gear is 0.3mm in module, 3.35mm in pitch diameter, $15^{\circ}$ in helix angle and the number of teeth is 12. All of the extrusion experiments were performed with internal helical gear die which was machined by precision electric discharge machining using the electrode. The experiment was conducted at $190^{\circ}C$ to $310^{\circ}C$ to obtain extrusive and mechanical properties. The extruded helical gears were analyzed through extrusion load, Vickers hardness and SEM images for each extrusion temperature. The powder hot extrusion process was successfully applied to fabricate a miniature helical gear.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 고액공존금속의 성형기술 심포지엄(III) SYMPOSIUM ON SEMISOLID FORMING TECHNOLOGY(III)
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• pp.15-32
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• 1999

A relationship between stress and stain is very important to design a die to avoid defects of products during semi-solid forming process. Since the liquid will be of eutectic composition in alloys liquid segregation will result in significant or undesirable situation. The materials used in this experiment are A 357. A390, Al2024 alloys that is fabricated by the electro-magnetic stirring process from Pechiney in France. The compression test was performed by induction heating equipment and MTS. In order to prevent the liquid segregation these measured temperature would be useful to control of strain rate during compression test. The liquid segregation is controlled as change of the strain rate and solid fraction during the compression process, The characteristics of flow between solid and liquid phase considering liquid segregation is examined through the above experiments. In the case of medium and high volume fractions of solid the distribution of strain rate is calculated by using compression test data of semi-solid materials (SSM). The thixoforming experiments with the designed die are carried out successfully. The die filling patterns of SSM for variation of die temperature and pressing force have been investigated. The hardness of the thixoformed scroll products is evaluated in terms of the microstructure for each position.