As a heating method for RHCM (Rapid Heating Cycle Molding) various heating technologies such as high frequency induction heating, IR heating, gas heating, and high temperature steamare applied, but these methods are not satisfying high productivity due to low energy efficiency. Research has been actively conducted on RHCM based on planar heating elements with high heating efficiency, such as carbon nanotubes, which are applied. To apply the CNT web film to the RHCM, a heating element must be applied inside the injection mold and power must be applied. As electricity is directly applied to the CNT web film to generate heat, all mold parts in contact with the CNT web film must be insulated, and high heat transfer is required for rapid heating performance. Thus, in this study, a multi-layer structure mold module for insulation and high heat transfer was designed to enable rapid heating by applying a CNT web film as a heat source. To this end, we intend to present a research direction for the commercialization of rapid heating molds, by identifying the main variables of rapid heating through heating experiments by the mold metal and insulator materials, and reflecting them in the mold design.
Injection molding is one of most widely-used polymer processing technologies in which hot polymer fills a mold cavity, and is solidified during the subsequent cooling process. In the mold filling stage, the mold temperature should be high to improve flow characteristics, and low to reduce cooling time during the cooling stage. To fulfill these objectives, rapid mold heating technology has been developed to raise mold temperature, without significant increase in cycle time. While the conventional rapid heating technologies required dedicated facilities such as steam heating or high-frequency induction heating system and has a limitation in uniform heating, the purpose of this study was to develop a facile and conformal mold heating unit that uses a carbon nanotube (CNT) film heater. The CNT film heater was used to heat a curved mold with high temperature uniformity, by maintaining uniform distance from the mold surface. The developed conformal heating technology was then applied to a singly curved mold and a multiply curved mold. Considering that the resulting temperature uniformity is superior to the conventional oil heating, the conformal mold heating technology using the CNT film heater can be used to improve part quality and productivity in various molding processes.
The design of the injection mold cooling system is important. The cooling time consumes 70-80% of the injection molding cycle, so a well-designed cooling system can shorten the molding time and improve productivity significantly. Recently, many studies have been conducted for rapid cooling of a hot-spot area using CO₂ in injection molding. In this study, a cooling module based on CO₂ was designed and manufactured for uniform and rapid cooling of an injection mold with a large cavity, and cooling characteristics were investigated through experiments. As the CO₂ supply pressure increased, the cooling effect increased significantly, while the cooling uniformity decreased relatively. In the case of using the heat exchanger, the cooling effect increased by 10oC on average compared to the case without the heat exchanger, whereas the effect on the cooling uniformity was insignificant. When the CO₂ was injected from both sides, the cooling effect increased by approximately 8oC on average compared to the case of injection from one side, and the cooling uniformity was approximately 10% higher. By using a heat exchanger and applying CO₂ bidirectional supply, a cooling rate of up to 5.78℃/s and an average of 4.9℃/s could be achieved.
Rubber is positioned as an important material and essential tool and means for mass production of products in all industries due to its unique properties such as sealing, elasticity and shock absorption. However, in the case of conventional press rubber molding, its energy efficiency is low due to considerable heat loss, and the deviation of the temperature distribution of the molding mold is high due to the indirect heating method in which heat is transferred to the upper and lower molds installed on hot plates. The upper and lower heating plates were heated by several heaters installed on the hot plates. The high deviation of the temperature distribution causes unformed defects. Among the rubber mold working methods that consume considerable energy, this study attempted to reduce energy consumption by directly heating the mold via installing a heater inside the upper and lower molds in a compression mold with large energy loss. As a result, compared to the conventional method of transferring heat to the mold by heating the hot plate of the press, energy was saved by 30%, the initial mold heating time was shortened by 20 minutes, and the product defect was reduced with a rate of 25%.
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Enabling Technologies for Thermal Management During Permanent Mold Casting: A Critical Review Cheolmin Ahn, Carl Söderhjelm, Diran Apelian International Journal of Metalcasting.2025;[Epub] CrossRef
The purpose of this study is to propose a better contact surface pattern of a heat radiating block in a progressive GMP (Glass Molding Process) heating assembly. In this study, a simulation model based on FEM was developed to perform a thermal analysis for the heating assembly. It was verified by comparing experimental results. The temperature distribution on the heating block surface and heating energy consumption was analyzed with the change of contact surface pattern and area of a heat radiating block. The considered pattern on the contact surface was cross (+) and straight (-) shape. The contact area ratio was changed from 16 to 100%. The simulation results show that the heating energy consumption increased to reach a target temperature with the increase of contact area ratio. The straight-shaped patterns on a heat radiating block presented more uniform temperature distribution on the mold heating surface than the cross shaped surface, whereas it resulted in a slightly higher energy consumption of up to 9%. This study shows that the contact surface pattern on a heat dissipating block can control the temperature distribution on the mold heating surface.
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In this study, we proposed microphone array and algorithm for sound source localization based on GCC-PHAT for the robot searching victims in a narrow space. Through frequency domain analysis, we designed filter to make algorithm react only to the sound with a human voice frequency. Additionally, calibration algorithm was integrated to solve the problem of the update cycle of result value becoming very short when passing through the filter, presenting difficulty in checking the value. Results obtained through experiments verified the performance of the proposed microphone array and sound source localization algorithm.
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Industrial robot manipulators require high absolute position accuracy of the end effector to perform precise and complex tasks. However, manufacturing errors cause differences between nominal and actual parameters, and errors between the expected and actual positions of the end effector, resulting in undesired lower absolute position accuracy. Accordingly, to increase the absolute position accuracy of the end effector, kinematic calibration is required to correct the nominal parameters close to the actual parameters. However, in this study, redundancy of parameters may occur from the overlapping degrees of freedom of parameters in adjacent frames, which causes the problem of unnecessarily correcting many parameters in the optimization process. Thus, to solve this problem and use only the necessary parameters, this paper focuses on the linear relationship of redundant parameters and proposes a method of automatically discriminating and removing it through the Pearson Correlation Analysis. Additionally, through simulations on the two manipulator models, we verify the accuracy of redundancy of parameters determined by the proposed method, and demonstrate consistency and efficiency by comparing the results before and after redundancy removal.
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High-strength steel, which has higher strength than ordinary steel, has emerged as a representative lightweight material because of its superior price competitiveness and easy application of manufacturing processes compared to other lightweight materials such as nonferrous metals and sandwich plates. Thus, the purpose of this study was to reduce the thickness and light weight of parts by applying high strength steel more than 600 MPa to various body parts. TR590 and DP590 high tensile steels were applied to the reinforcement seat belt front top and bottom components respectively. To this end, the impact simulation was performed, and the safety of the parts was investigated through FE-Analysis. Prototype molding evaluation confirmed the possibility of mass production of reinforcement seat belt front upper and lower components, using high tensile steel.
This paper proposes a cycle time estimation algorithm of a CNC machine tool, using a block overlap based tool path generation algorithm. Velocity profile generation algorithm of CNC interpolator is proposed to compute the cycle time of the G-Code block. Because the CNC blends adjacent velocity profiles to reduce the cycle time and smooth the tool path, the cycle time is adjusted considering the block overlap. The in-position time of rapid traverse is compensated to improve the cycle time estimation accuracy. The simulation model was designed to estimate the cycle time of the CNC machine tool. A three-axis feed drive testbed was used to evaluate the cycle time estimation accuracy of the proposed algorithm.
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