• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1736-1745
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• 2002

The objective of this study is to predict the roll wear in hot rod rolling process. In this study hot rod rolling process for round and oval passes has been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the thermal softening of DCI (Ductile Cast Iron) roll according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering parameter curve. 3D wear program developed in this study might be used for adjusting the gap of rolls to set up a suitable rolling schedule for keeping dimensional tolerance of the product.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.969-974
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• 2014

Previously fabricated electronic devices were used for vacuum manufacturing processes such as conventional semiconductor manufacturing. However, they are difficult to apply to continuous processes such as roll-to-roll printing, which results in very high device manufacturing and processing costs. Therefore, many developers have been interested in applying continuous processes to contact printing or noncontact printing technologies and they proposed various continuous printing techniques instead of conventional batch coating. In this paper, we proposed improved gravure offset printing process as one of the contact printing technique. We used etching pattern geometry with soft core blanket roll for printing of ultra fine line below the 10um.Using this technique we obtained flexible metal grid mesh film as transparent conductive film.

• Journal of Mechanical Science and Technology
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• v.17 no.3
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• pp.321-328
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• 2003

The elongation of contact length on the line of action is considered with particular reference for roll forming of gears, and for dynamic behavior of the tooth in meshing. However there is no paper that discuss the elongation of contact length in the load meshing of gears. Based on our investigation, the contact length on the line of action elongates more than the kinematically calculated value. In rolling, as the tool approaches the workpiece, the center distance of the gears decreases by a small amount. But, the elongation of contact length is sensitive. Therefore, the contact point on the line of action is difficult to be determined, which complicates the tooth analysis. In this study, the exact relation between the elongation of contact length and the tooth space over the recess or before the approach are revealed by experiments and kinematic theory. This analytical result applies not only for rolling, but also for the single flank meshing which is done under constant center distance.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.614-618
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• 2002

In hot strip mills, Portable Roll Scanner (the portable roll surface temperature and profile measuring device) can be used to calibrate on-line Process models for strip crown and flatness by measuring the thermal expansion and wear profile of the rolls. And the surface temperature measurement can be used to optimize the roll cooling system. Portable Roll Scanner consists of the measuring device, which has two contact inductive distance transducers for roll profile measurement and one infrared Pyrometer for surface temperature measurement, and computer-based controller that is equipped with the measuring device. By the wireless data communication, the data is transferred to the memory of notebook for further analysis. After roll extraction from mills, Portable Roll Scanner measure the roll profile and surface temperature simultaneously along the work roll face and display the results in the TFT color monitor of notebook. Portable Roll Scanner is useful at mill-side and roll grinding shop.

• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.103-109
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• 2010

An ink transfer is modeled and experimentally verified using roll-to-roll electric direct gravure printing process. The ink transfer model based on the physical mechanism for the maximum ink transfer rate is proposed, and experimented by the electric printing machine in FDRC for the relations of the maximum ink transfer rates to the printing pressure, the operating speed, the operating tension, the surface roughness of substrates, and the contact angle between substrate and silver ink. The free ink split coefficient and immobilized ink under the maximum ink transfer rate are calculated by the physical parameter in a printing process and contact angle between substrates and ink. Numerical simulations and experimental studies were carried out to verify performances of the proposed ink transfer model. Results showed that the proposed ink transfer model was effective for the prediction of the amount of transferred ink to the substrate in a direct gravure printing systems.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.894-898
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• 2009

In a post printing section of roll to roll printing systems, scratch problem is the major defects. The functional qualities such as conductivity, mobility could deteriorate because of the scratch defect. In general, the scratch of the printed pattern on the flexible substrate was induced from a contact between rolls and printed pattern in the post printing section. In this paper, for non-contacting transfer of a moving web, a mathematical tension model has been developed considering strain due to air floatation and the proposed mode has been validated by numerical simulation. Additionally, the correlation between floatation height and speed compensation to control the tension and register are investigated. On the basis of the proposed model, a guide line of speed control in R2R printing system is presented to guarantee the non-contact between rolls and R2R printed pattern on the flexible substrate.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.111-115
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• 2006

High-finned tubes have good thermal conductivity and have better cooling efficiency than plain tubes or low-fined tubes due to bigger air contact area. During high-fined tubes are manufactured by roll forming, the main technique is illustrated to optimizing primary material(copper pipe), optimized die matrix designing technique for roll forming, control manufacturing speed to develop productivity etc. In this study, a roll forming system was developed in oder to produce high-finned tube. Also a multi-step roll forming die was designed & built to produce high-finned tube that has over 10 mm fin height. And then, roll forming test using copper pipe was performed to produce high-finned tube. Roll forming process for producing highfinned tube was optimized by analyzing and adjusting misrostructure, hardness, and surface roughness of roll formed high-fined tube.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.23-29
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• 2008

This study analyzes the rolled circular rod strip with radius of loom and length of 350cm by using finite element analysis. The material strength and its durability of the rolled strip can be predicted through this study. As the penetration tolerance by contact decreases, the contact rigidity of strip increases. As the contact rigidity becomes the highest at the elapsed time of 1.2 second, the contact stress becomes the lowest. On the contrary, von-Mises stress becomes highest at this time. The total deformation on strip increases from the upper part of strip at the position near to rotating roll to the lower part of strip at the position near to fixing roll.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.242-251
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• 1999

The temperature distribution over the work roll length was estimated by solving a 2-dimensional heat transfer equation based on the rolling conditions and the thermal boundary conditions. In order to solve the governing equation, a finite volume method was employed. In the rolling conditions, the strip temperature, the contact time between roll and strip, the roll speed, the strip thickness, the rolling force and the rolling and idling time were used as input data. In order to verify the accuracy of temperature estimation, roll surface temperatures were measured in the roll shop. The measured temperatures showed a good correlation with the calculated ones.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1881-1888
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• 2003

This study show a numerical method to predict roll wear in the roll forming process. Archard's wear model was reformulated in an elemental form to predict volume of roll wear and then wear depth on the roll was calculated using the results of finite element analysis. Abrasive wear occurs at contact area in the roll forming process and the results of simulation are compared with experimental data in production line. The wear simulation approach with 3-D FEM program for roll forming process, SHAPE-RF is in good agreement with it in tendency.