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Thin glass processing with radio wave assist

Post Time:Aug 11,2009Classify:Glass QuotationView:730

A significant breakthrough in the process for tempering very Thin Glass

The author PREM BOAZ presents the advantages of the use of Radio Wave energy (RW energy) in the forming of glass (in general) and of tempering thin glass of less than 3.00mm (in particular). Some of the inherent problems in the conventional thermal tempering of thin glass are also presented. The means to control and to apply the RW energy to assist in the thermal tempering process is discussed in detail.

 

 

 



 


 

 


Inside view of the  RW chamber showing the bar electrodes with the top quench removed.

 

 




An actual temperature profile comparison. (This data was collected on an earlier version of the machine using 150mm X 150mm glass samples)

 


 

 

 


 


 


 


The “Bar” electrodes are placed along the length of the glass as close as possible to the edges

 


Thermo gram of ½ of a 12” X 12”  glass taken through the 6” port hole before and after it is exposed to RW for 5 seconds

 

 


 


 

 


 


 

 

AN OBSERVATION ON RW HEATING OF GLASS

 

<!--[if !supportLists]-->         <!--[endif]-->When pre-heated glass is heated by RW at a rapid rate, the viscosity of the glass drops in concert with the rise in temperature

<!--[if !supportLists]-->         <!--[endif]-->This is in contrast to heating the glass by conventional methods where the change in viscosity lags the rapid rise in temperature

<!--[if !supportLists]-->         <!--[endif]-->The indications are that RW heating modifies the Thermal – Viscosity - Elastic properties of the glass seen in conventional heating process.

<!--[if !supportLists]-->         <!--[endif]-->There are further indications that the thermal tempering effect of the quench system is more efficient when the glass is heated to it’s softening point using RW energy.


 

 



 


 

Variable heating: Thermo gram of a 12” X 12” panel of glass before and after the RW is turned on for 5 seconds. The heating area is split in two with one electrode along the middle and two electrodes at the edges. The power level is controlled by the distances of the electrodes from the edges

 

 

 


 


 




 

The bar electrodes are closer to the leading edges to apply more heat in that area

 

 

Two inside views of the RW chamber used to temper 12” X 12 “  and 300mm X 300mm glass panels











EDGE TENSION AND SURFACE COMPRESSION


 

Note: The Lab- (Vitro Automotriz ISO/TS 16949) – data shown above indicates that the parts tested were “Fully Tempered”

 

CONCLUSIONS

 

● RW energy when applied to pre-heated glass is capable of further heating the glass to a higher target temperature

● RW energy when applied to the glass through properly placed bar electrodes is capable of providing a uniform rise in glass temperature

● RW energy allows for heating of a glass panel at different rates at different locations in a controlled manner by arranging the locations of the bar electrodes

● The RW chamber kept at room temperature allows for the quenching cycle to start within a fraction of a second from the end of the heating cycle

 

CONCLUSIONS (cont’d)

 

● The RW energy appears to affect the viscosity of the glass in unison with the rise in temperature of the glass even when the glass is heated at a rapid rate.

 

● The RW system presented here can be incorporated on to most existing glass processing machines.

 

● This RW system improves the glass tempering capability down to 2.00mm or less from the conventional capability of about 3.00mm.

Source: GlassonwebAuthor: shangyi

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