• 소성∙가공
• /
• 제32권6호
• /
• pp.335-343
• /
• 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.

• 한국기계가공학회지
• /
• 제19권5호
• /
• pp.75-81
• /
• 2020

Multistage hot forging process enables mass production of various parts at a high speed, wherein, it is important to design the forging steps in an optimal way. Finite element methods are widely applied for optimizing the forging process design; however, they present inaccurate results due to the rapid change in the mold temperature during multistage hot forging. In this study, the temperature distributions of the mold in a steady state were calculated via heat transfer analysis during mold cooling. The flow stress and friction coefficient of the material were measured according to the temperature and were applied for numerical analysis of the multistage hot forging process. Eventually, the accuracy of the analysis results is verified by comparing these results with the experiments.

• 한국정밀공학회지
• /
• 제15권12호
• /
• pp.62-67
• /
• 1998

An experimental study has been carried out to investigate casting process parameters which influence on the microstructures of cast preforms in casting/forging process of aluminum alloy. In the casting process, pouring temperature, pouring time, mold temperature, mold material, and, cooling method are selected as process parameters. With the cast preform, a forging test has been performed to compare mechanical properties of final products between casting/forging process and forging process. From the experimental results, low mold temperature and water cooling method are favorable for obtaining minute microstructures of cast preforms. Casting defects included in cast preforms. such as pores and shrinkage cavity, are eliminated by the forging process. And comparing cast/forged products with conventionally forged products, the former are almost as same as the latter in mechanical characteristics.

• 한국기계가공학회지
• /
• 제20권12호
• /
• pp.8-15
• /
• 2021

Cold forging is a method in which molding is performed at room temperature. It has a high material recovery rate and dimensional precision and produces excellent surface quality, and it is mainly used for the production of bolted or housing products. The lifespan of cold forging molds is generally determined by the wear of the mold, plastic deformation of the mold, and fatigue strength. Cold forging molds are frequently damaged due to fatigue destruction rather than wear and plastic deformation in a high-temperature environment as it is molded at room temperature without preheating the raw material and mold. Based on the results analyzed through FEM, an effective mold structure design method was proposed by analyzing the changes in tensile and compressive stresses on molds according to the number of molds and reinforcement rings and comparing the product geometry and mold stress using three existing mold models.

• 한국자동차공학회논문집
• /
• 제12권3호
• /
• pp.122-129
• /
• 2004

In plastic working, as working becomes speedy, automatic and working condition deteriorates, the increase of forging working has been remarkable. Therefore, we need the estimation of mold lift in detail, in order to counterplan of effective mold life extension. In this study, on the SKH51, mold steel which is forged by cold working and the KCW1, tool steel of low alloy, we estimated mold life on the base of FEM analysis and investigated mold lift by low cycle fatigue test. Also, this paper suggested a new method of estimation of mold lift.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.1113-1118
• /
• 2008

In the hot forging process, The forging defects that are caused by metal were strain, temperate, and inclusion. In this paper, the computer simulation analyzed the effective plastic strain and temperature behaviors. The quantitative analyses which proposed the effective mold design of S/CAM shaft was executed. The parameters of forging shape that affected on the optimize conditions that was calculated with simple equation were investigated. it is expected that the developed analysis model and design technique would greatly contribute to the drum brake optimal design considering temperature affected and material behaviors. This development could save more than 20% of production cost and reduced failure rate to more than 30%. By improving the life span of mold from 15,000 to 25,000, financial difficulty of company imposed on a mold manufacture could be overcome.

• Design & Manufacturing
• /
• 제14권3호
• /
• pp.17-22
• /
• 2020

As devices such as smartphones, tablet PC, and wearable devices have been miniaturized, the connectors that go into the devices are also designed to be very small. The connector combines the plug and the receptacle to transfer electricity. As devices are miniaturized, the contact shape is formed by partially thinning the thickness of the raw material of the terminal in order to lower the coupling height of the plug and receptacle. The product used in this study is a receptacle terminal used for 0.4mm pitch board to board connector among fine pitch connectors. When the material thickness is reduced by forging the receptacle terminal, the width change of the pin is checked. To reduce the thickness of the material by forging, pre-notching is applied in the first step, forging in the second step, and notching in the third step. After forming the width dimension of the pin to 0.28 mm in the pre-notching process, in the forging process, the material thickness 0.08 mm and 0.02 mm (25%) were forged and the thickness was changed to 0.06 mm and the width change amount of the pin was measured. The facility produced 10,000 pieces at 400 SPM using a Yamada Dobby (MXM-40L) press, and thirty pins were measured and the average value was shown. After forging by using C5210-H (HP) and NKT322-EH, which are frequently used in connectors, analyze the amount of change in each material. The effect of punching oil on forging is investigated by appling FM-200M, which is highly viscous, and FL-212, fast drying oil. This study aims to minimize mold modification by predicting the amount of material change after forging.

• 동력기계공학회지
• /
• 제16권5호
• /
• pp.70-75
• /
• 2012

In mechanical industries, forging is one of the basic process. But comparing the other developed industries, forging industries can not reach at the level of that development. In forging industries, the quality of the products totally depends on the skills of workers and also the precision of the equipments. Particularly because the open die forging industry is unable to deviate from the past method of production and all works are manually progressed, the operator is always exposed to the danger. In the regard some additional device has been made especially. Thus, in this research, by using the forklift as the means for the manipulation of the development object system, it tries to be comprised the process automation. After than it is fitted with the forklift for safe and easy handling of jobs and products during open die forging process. First of all, development system mold has been assembled to the system, after than it is assembled with forklift. This development system has been applied for handling of large scale products more than 300kg, and the satisfactory result with uniform quality of the products have been achieved due to this mechanical setup.

• Design & Manufacturing
• /
• 제15권1호
• /
• pp.14-20
• /
• 2021

The objective of this study is to introduce the new possibility of sensing technology based on inductive displacement sensors to monitor the status of wheel position in the hot forging process. In order to validate effectiveness of proposed sensing technology, the indirect forging force measurement with displacement sensor was applied into a typical closed hot forging die-set used for the manufacturing of flange bolts. The locations to implement the displacement sensor were selected carefully by simulating forming process and static structural. From the measurement results of the forging force change during one hot forging cycle, it was found that the proposed monitoring system can provide useful information to understand the detailed behaviors of die-set in the closed hot forging process.

• Design & Manufacturing
• /
• 제6권2호
• /
• pp.24-30
• /
• 2012

In this study, the hot forging technology for precision forming of spline teeth of the inner race in the auto-transmission was developed in order to minimize its finishing allowance. Several blocker and finisher shapes for the precision hot forging process of the inner race were proposed and the forging processes were analyzed using the three-dimensional finite element method. The optimum hot forging process was obtained considering some parameters such as metal flow patterns, forging defects and forming load. Blocker and finisher dies for the hot forging process were designed by selecting the most suitable shapes obtained from the finite element analysis. Experimental works were also performed in order to verify the optimum design of hot forging process.