• Title/Summary/Keyword: Forging defects

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Development of Spur Gear Parts for Automotive Actuators using Precision Cold Forging Technology (정밀냉간단조 기술을 적용한 자동차 액추에이터용 스퍼기어 부품개발)

  • D. H. Park;S. C. Han
    • Transactions of Materials Processing
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    • v.32 no.6
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    • pp.335-343
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    • 2023
  • Spur Gear parts for automobile actuators using existing former forging technology were produced in a total of three processes on a former forging machine. However, in order to improve cost increase due to frequent mold breakage, Spur Gear parts were designed and manufactured in the cold forging process after forming the preform through former forging. In other words, in the existing former forging mold, product seating defects occurred due to horizontal movement, resulting in many product defects and mold damage, so there was an urgent need to improve mold life and product defects. In order to improve this, we tried to improve the mold life by improving the existing 3 former forging processes to a former forging process and 2 cold forging processes. Therefore, We developed Spur Gear parts for automobile actuators were developed by applying precision cold forging technology through a former forging process and 2 cold forging processes to improve mold life.

Forging Defects Analysis by Full 3-Dimensional Simulation based on F.V.M. (단조품 결함에 대한삼차원 단조 공정 해석)

  • 박승희;제정신
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.216-220
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    • 2003
  • Most important for meaningful forging simulation is the determination of correct process parameters. In addition a check and a compensation of the data base after the comparison between experiments and the computation of the developed process is necessary. The existence of a systematic process parameter data bank for special kinds of forming process in combination with forging specific simulation lifts the value of the products. Finite volume method is applied to simulate the hot forging process to investigate the defects for the automobile product. Three typical forging processes have been investigated; Extrusion by hydrolic press, Upsetting by crank press and Inclined upsetting by hammer press. Simulated result has compared with the experiment and provided a direction to improve the process.

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The Effect of Pressure on Liquid Segregation in Direct Rheo-Forging Process of Aluminum Alloys (알루미늄 소재의 레오로지 직접단조공정에서 가압력이 액상 편석에 미치는 영향)

  • Oh, S.W.;Bae, J.W.;Kang, C.G.
    • Transactions of Materials Processing
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    • v.16 no.3 s.93
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    • pp.178-186
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    • 2007
  • Rheo-forging process of aluminum alloy is suitable for large parts of net shape without defects and excellent mechanical properties in comparison with conventional die casting and forging process. To control the microstructure of the product with high mechanical properties in rheo-forming, solid fraction is required to prevent porosity and liquid segregation. Therefore, in rheo-forging process, die shape, pressure type and solid fraction are very important parameters. The defects such as porosity, liquid segregation and unfitting phenomena occur during rheo-forging process. To prevent these defects, mechanical properties and microstructure analysis of samples versus the change of pressure are carried out and the problem and its solutions are proposed. Also, the mechanical properties versus various pressures were compared with and without heat treatment. The alloys used for rheo-forming are A356 and 2024 aluminum alloy. The rheology material is fabricated by electromagnetic process with controlling current and stirring time.

A Study on the Development of Cathode-Ray Tube Die Using Hot forging (열간단조를 이용한 브라운관 금형의 개발에 관한 연구)

  • 차도진;조종래;배원병;황남철
    • Transactions of Materials Processing
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    • v.9 no.5
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    • pp.533-538
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    • 2000
  • This study has been carried out to develop a CRT die using hot forging. The conventional CRT die made by casting has defects such as void and inclusion. These defects of the cast die make micro-spots on the surface of the CRT which affect the quality of the final product. So, a hot forging process is developed to avoid these defects of CRT die by the model material test and the rigid-plastic FEM. Firstly, model material tests are carried out with plasticine billets in order to investigate the material flow pattern in the die cavity and to get the reasonable initial values for designing the preform in the FE simulation. And then a finite element analysis has been performed to Predict the preform and the forging load of a CRT die. We also suggest an integrated die-set which combines two die-sets into one die-set to save manufacturing time and cost in case of similar die-size.

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Hot Forging Design for a Large Scale Compressor Wheel (대형 압축기 휠의 열간단조 공정설계)

  • 임정숙;염종택;김현규;박노광
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.47-50
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    • 2003
  • Hot-forging Process and die design was made for a large-scale compressor wheel of Ti-6Al-4V alloy with 2-D FE analysis. The design integrated the geometry-controlled approach and dynamic materials modelling(DMM). In order to obtain the processing contour map of Ti-6Al-4V alloy based on DMM, compression tests were carried out in the temperature range of 915$^{\circ}C$ to 1015$^{\circ}C$ and the strain range of 10$\^$-3/s$\^$-1/ to 10s$\^$-1/. In the die design of the compressor wheel using the rigid-plastic FE analysis, forging dimensional accuracy, the capacity of the forging machine and defect-free forging were considered as main design factors. The microstructure of hot forged wheel using the designed die showed a typical alpha-beta structure without forging-defects.

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Influence of Cropped Initial Billet Shape on the Dimensional Tolerance and Tool Life (크로핑 된 초기소재 형상이 금형수명 및 제품의 정밀도에 미치는 영향)

  • Lee D. J.;Kim D. J.;Kim B. M.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.10a
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    • pp.86-89
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    • 2000
  • In cold forging by multi stage former, crowing process is important process for the high production rate and automation of forging process. But various cropping defects occur in cropping process such as orthogonality, ovality and unevenness, etc. These defects have harmful effects on the dimensional tolerance of products and tool life. So in this study, the cropping experiment is performed to examine influence of cropping process variables(clearance, cutting velocity, H/D) on occurrence of crowing defects and optimum process variables are selected, and then FE analysis is performed to verify influence of these defects on dimensional tolerance and tool life.

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Analysis of the upsetting type process for spur gear cold forging using 3D-FEM (3차원 유한요소법을 이용한 Upsetting Type Spur Gear 냉간 단조 공정 해석)

  • Chun S.H.;Lee Y.S.;Kwon Y.N.;Lee J.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.05a
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    • pp.135-138
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    • 2004
  • Since the upsetting type is superior to an extrusion type to get the dimensional accuracy of cold forged spur gear, the upsetting type process far spur gear cold forging has been studied. FE analysis of upsetting type process fur spur gear cold forging was performed to investigate about flow pattern of workpiece and die stress. To analyze the elastic characteristics of die, both rigid and elastic material model were used during loading stage. Under-filled defects were detected In lower portions of spur gear forged by upsetting type in experimental. When the elastic material model for die was used, the under-filled defects could be predicted. On the other hand, if the material model of die was rigid, the defects could not been presented because the die deflection was not considered.

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A Study on the Elimination of Surface Defect and Increase in Tool Life of the Warm Forged Spider (온간 스파이더 표면결함 개선과 금형수명 향상에 관한 연구)

  • Kang, Jong-Hun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.5
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    • pp.82-90
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    • 2020
  • Due to the complicated shape of the spider, the production method was changed from cold to warm forging. Finite element analysis was performed to predict the forging load and shape using the enclosed hydraulic die set. As the forging load increases due to the spider die volume, die stress analyses were performed to optimize the die design in order to reduce the die stress in various conditions. Large deformation while producing the complicated forging parts induces high forging load, which is one of the main parameters of the forging surface defects. The forging process was analyzed to find out the root cause of the surface defects generated during the spider production for various parameters, thereby revealing that the radius of die in the defect zone influenced the air trap depth, being the root cause of the surface defect. It was verified that die life was increased and the surface defect was eliminated by changing the die design during the mass production test.

Evaluation of Cooling Process for Marine Shaft Forging Products (선박용 축류 단조품 냉각공정 평가)

  • Park, Sang-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.9
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    • pp.352-357
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    • 2020
  • This study was performed to solve the quality problems of forging propeller shaft components in the marine diesel engines during the final cooling process and provide reasonable guidelines to increase the production of forging products. Residual hydrogen existing on the inside of forging products begins to diffuse and accumulates at the pores, micro-fissures, and grain boundaries as the temperature of forging products begins to decrease and reaches a critical temperature range, and finally transforming into internal defects. These defects were easily found near the surface of products after milling the surface of forging products. In this work, four types of forging products (shaft flange, shaft journal, thrust shaft, and propeller shaft) were chosen to evaluate the temperature history of products during the cooling process, employing non-linear numerical analyses with the ANSYS program. The times elapsed to reach 250 ℃ after cooling were approximately 9 ~ 23 hours for each forging product. These times can be used as cooling process guidelines on the quality and productivity of products after heat treatment.

Finite Element Analysis for Improvement of Folding Defects in the Forging Process of Subminiature Screws (초소형 나사 단조시 접힘결함 향상을 위한 유한요소해석)

  • Lee, Ji Eun;Kim, Jong Bong;Park, Keun
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.6
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    • pp.509-515
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    • 2015
  • Recent trends to reduce the size of mobile electronics products have driven miniaturization of various components, including screw parts for assembling components. Considering that the size reduction of screws may degenerate their joining capabilities, the size reduction should not be limited to the thread region but should be extended to its head region. The screw head is usually manufactured by forging in which a profiled punch presses a billet so that plastic deformation occurs to form the desired shape. In this study, finite element (FE) analysis was performed to simulate the forging process of a subminiature screw; a screw head of 1.7 mm diameter is formed out of a 0.82 mm diameter billet. The FE analysis result indicates that this severe forging condition leads to a generation of folding defects. FE analyses were further performed to find appropriate punch design parameters that minimize the amount of folding defects.