Modeling the Embossing Stage of the Ultrasonic‐Vibration‐Assisted Hot Glass Embossing Process

Nguyen, Lan Phuong; Hao, Kei Chon; Su, Yi; Hung, Ching-Hua

doi:10.1111/ijag.12090

Cited by 13 publications

(6 citation statements)

References 12 publications

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“…Furthermore, Hung et al [6] reported that embossing forces reduced markedly when applying ultrasonic vibration into hot glass embossing process. In addition, some experiments were carried out to study effect of some parameters on force reduction under effect of ultrasonic vibration by using different embossing speeds, changing various embossing temperatures and extending the applying time of ultrasonic vibration [7]. Recently, Nguyen et al [8] have tried to emboss the rectangular pyramid arrays on the glass substrate using ultrasonic vibration assisted-hot embossing process.…”

Section: Fig 3 Ultrasonic Vibration-assisted Hot Glass Embossing Processmentioning

confidence: 99%

Effect of Ultrasonic Vibration on Increasing Embossing Speed during Hot Glass Embossing Process

Nguyen

Hung

2019

AMM

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Nowadays, microstructures have an important role in optical products as well as in optical systems. Beside machining methods, hot glass embossing is recently a novel technology to manufacture microstructures in optical components with high quality and low cost. Especially, this technology has been assisted efficiently by ultrasonic vibration. Previous studies showed that high energy of ultrasonic vibration would lead to the temperature rise inside the glass so that the material was easily embossed into the microcavities on the mold. Thus, micro-formability of glass material has been especially improved efficiently. However, there were no studies focusing on effect of ultrasonic vibration on embossing speed in this process. Therefore, this work is aimed to utilize ultrasonic vibration to improve the embossing speed of hot glass embossing process. K-PSK100 optical glass was used as the material for all experiments. Pyramid array with size of 30 × 30 × 20 μm and period of 150 μm was created on the mold. Microstructure hot embossing experiments were conducted for both conventional process (without ultrasonic vibration) and ultrasonic vibration-assisted process (frequency of 35 kHz and amplitude of 3 μm). By fixing the embossing temperature of 430 °C, the embossing speeds of 0.05 mm/min, 0.10 mm/min and 0.15 mm/min were applied, respectively. Experimental results showed that in case of conventional process, the faster embossing speed, the smaller final height of pyramid structures. Nevertheless, this obstacle was resolved by ultrasonic vibration. Under heating effect of ultrasonic vibration, the glass still filled well into the pyramid cavities on the mold even when the high embossing speed was applied. Measurements indicated that in the same experimental conditions (temperature and speed), ultrasonic vibration could improve the filling ability of the glass to 18 %. This finding could be used to optimize the experimental conditions to increase the productivity of the microstructure hot glass embossing process.

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Section: Fig 3 Ultrasonic Vibration-assisted Hot Glass Embossing Processmentioning

confidence: 99%

Effect of Ultrasonic Vibration on Increasing Embossing Speed during Hot Glass Embossing Process

Nguyen

Hung

2019

AMM

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“…Since the formed contact angles are determined by internal stresses of the glass and glass‐mold interfacial frictions, this difference indicates that the contact mechanical characteristics on glass‐mold interfaces are transformed in UGMP. More likely, the average contact pressure and average frictional force are reduced, which have been demonstrated in Nguyen's and Zhou's experimental results …”

Section: Discussion On Micro‐formabilitymentioning

confidence: 99%

“…It was concluded that the high energy of the ultrasonic vibration would lead to a temperature rise in glass K‐PSK100. Consequently, the molding pressure was dramatically reduced, while the microformability of the glass was significantly improved . On the other hand, Zhou and Xie studied the mechanism of UGMP based on the ultrasonic mechanical effect, and the results showed that the ultrasonic vibration could reduce the contact time between the resin preform and molds, as well as homogenize the stress distribution inside the formed microgrooves.…”

Section: Introductionmentioning

confidence: 99%

Mechanism study on microformability of optical glass in ultrasonic‐assisted molding process

Luo

Nguyen

et al. 2018

Int J of Appl Glass Sci

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Ultrasonic‐assisted glass molding process (UGMP) has gained a promising start in microptics fabrication in recent years. To further understand the microforming process and comprehensively evaluate the microformability of the glass in UGMP, theoretical considerations and numerical simulations are performed in this study. A generalized dynamic viscoelastic model of glass in UGMP is first reformulated based on the ultrasonic thermo‐mechanical effects. Correspondingly, a multiphysics numerical model of UGMP is developed to dynamically observe the thermo‐mechanical rheological behaviors of the L‐BAL42 glass inside the microscale mold cavities. The stress distributions and deformation features of the formed micro‐V‐grooves in different molding processes are further employed to fully investigate the ultrasonic mechanical and thermal effects on glass molding. The results show that, as a product of the combined ultrasonic mechanical and thermal effects, the filling rate of the glass in UGMP is observably increased and homogenized, while its maximum forming stress is reduced by 57.6% compared with the conventional molding process (GMP). It is also found that, the ultrasonic thermal effect is dominant in lowering the forming stress of the glass, while the ultrasonic mechanical effect plays a leading role in homogenizing the filling rate of the glass. This study will provide both theoretical and technical supports for high‐efficiency and high‐precision fabrication of surface‐relief microptical elements.

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“…This model could not only describe the glass behavior under embossing force but also express the effect of ultrasonic vibration. Standard linear solid (SLS) model, one kind of viscoelastic models, which combines a Maxwell model and a spring in series, was proposed for the glass deformation behavior during the embossing stage [8] (as shown in Figure 17). Substituting complex strain and complex stress from Eq.…”

Section: Finite Element Analysis Of Ultrasonic Vibration-assisted Hotmentioning

confidence: 99%

Ultrasonic Vibration-Assisted Hot Glass Embossing Process

Nguyen¹

2019

Noise and Vibration Control - From Theory to Practice

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This chapter is intended to provide the reader with background information about the assistance of ultrasonic vibration in hot glass embossing process. For this purpose, the description of the conventional hot glass embossing process and the ultrasonic vibration-assisted hot glass embossing process will be defined first. Based on the comparison between these two processes, components of the ultrasonic vibration device which produces ultrasonic vibration will be discussed in principle. Among these components, ultrasonic horn will be especially analyzed. After that, each interesting effect of ultrasonic vibration on hot glass embossing process will be explained in detail. With the development and application of simulation tools on forming process, this chapter will finally describe some results of finite element analysis (FEA) of ultrasonic vibration-assisted hot glass embossing process.

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Modeling the Embossing Stage of the Ultrasonic‐Vibration‐Assisted Hot Glass Embossing Process

Cited by 13 publications

References 12 publications

Effect of Ultrasonic Vibration on Increasing Embossing Speed during Hot Glass Embossing Process

Effect of Ultrasonic Vibration on Increasing Embossing Speed during Hot Glass Embossing Process

Mechanism study on microformability of optical glass in ultrasonic‐assisted molding process

Ultrasonic Vibration-Assisted Hot Glass Embossing Process

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