GB2266713A

GB2266713A - Glass toughening quench system

Info

Publication number: GB2266713A
Application number: GB9127451A
Authority: GB
Inventors: Michael Bryan Land
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-12-28
Filing date: 1991-12-28
Publication date: 1993-11-10
Anticipated expiration: 2011-12-28
Also published as: GB9127451D0; GB2266713B

Abstract

The air quench system described is a system to provide large volumes of high velocity air directed onto the surfaces of sheet glass to rapidly cool and thus toughen the glass. This is achieved by the use of specially designed compressed air ejectors fitted in manifolds. Compressed air escapes at very high velocity into the throat of the nozzles, and draws into the nozzle cap a much larger volume of atmospheric air. This provides the high volume of quenching air directed onto the glass surfaces. <IMAGE>

Description

OVERVIEW OF AIR QUENCH SYSTEM The air quench system is to be used to rapidly cool glass sheets in a glass toughening process.

The success of a heat treatment glass toughening system depends mainly upon the even rapid quenching of the glass on both sides. This is most successfully achieved for architectural glass by directing a large volume of high velocity air onto the glass surfaces.

The common technique used to obtain this air flow is using a large fan ducted into plenum chambers for distribution. My design uses an array of specially designed air ejectors to amplify a small amount of higher pressure compressed air to achieve the same high rate of heat transfer. This method allows for a plant to be of about half the physical size of a fan driven plant. It also reduced the connected electrical power required from between 400Kw and 700Kw, to about 200Kw.

During the heating cycle of the glass toughening process compressed air is stored in air receivers interconnected by large bore pipes. The air is filtered and dried during the compression process to prevent ingress of contaminants to the quench nozzles.

The final pressure can vary between 7 bars and 15 bars depending upon the capacity and pressure rating of the storage system. During the quenching cycle the stored compressed air is rapidly discharged through a computer controlled flow control valve. This valve maintains a downstream pressure of between 2.5 bars and 6 bars in a manifold system supplying the quench nozzles to cool both side of the glass. The control maintains the selected pressure by adjusting the flow to compensate for the decaying stored air pressure. The nozzle arrays are fitted into distribution manifolds to provide a quench system of circular air jets at a pitch of between 40mm and 60mm. The compressed air enters the individual nozzles from the distribution manifolds. It then escapes at very high velocity through an outlet gap between .05mm and .125mm.This circular jet of air follows the internal profile of the nozzle, and causes a pressure drop in the nozzle inlet. The pressure drop causes atmospheric air to be drawn into the nozzle at high speed and results in an amplified jet of high velocity high volume low pressure air being directed onto the glass surface.

The quench nozzle consists of a Nozzle Cap which is fitted onto the Nozzle and adjusted to provide the required Nozzle Gap. The Nozzle Stem is bonded to the opposite side of the Nozzle, to provide the channel for the exiting high velocity cooling jet. After setting the Nozzle assembly is fitted into the box section manifold to provide a complete assembly of multiple Nozzles. The length of the assembly can be varied according to the size of glass to be quenched. Each end of each manifold is connected to the main stored air system, down stream of the control valve. The controlled compressed air pressurises the manifolds, and the high pressure air travels through the High Pressure Airway. The High Pressure Air flows into the expansion chamber, and then escapes at high velocity through the Ejector Gap. The exit from this gap is machined to a specific profile, which causes a pressure drop at the Nozzle surface. This pressure drop forces the stream of air to follow the profile into the throat of the Nozzle. The flow of high velocity air in the throat of the Nozzle entrains a larger volume of atmospheric air into the main Nozzle inlet, and provides a sufficient volume of cooling air at the end of the stem, to quench the glass to provide a good commercial quality of toughness. The various parts and a general assembly can be seem on the two drawings attached.

Claims

1. A glass toughening quench system comprising compressed air ejector nozzles fitted in multiples into manifolds to provide arrays of nozzles set to discharge an even hitch volume flow of high velocity air along the length o the array.The ability of the nozzle to amplify a small volume of compressed air produces the high volume of lower pressure air required, by inducincr the flow of atmospheric air through the nozzles. The array sets are assembled in position over and under to provide quenching over the whole area of the load. Each level of arrays (i.e.upper and lower) can be maintained at different pressures to provide adjustment of the rate of quench to each side of the load.

During the quench cycle the pressure in the array manifolds is held at the predetermined level by adjusting the main flow control as the stored compressed air pressure decays.

The compressed air is replenished briny the time that the net load is being heated.

2. A glass. toughening quench system as claimed in Claim 1 utilising individual air ejector nozzles assembled at intervals along a manifold with the discharge tube fitted through the manifold enabling ambient air to be drawn in from the one side of the manifold and discharge from the other.

A glass toughening quench system as claimed in Claim 1 or Claim 2 that utilises multiple manifolds as required to provide air over any size of area.

4. A glass toughening quench system as claimed in Claim 1 or Claim 2 or Claim 3 incorporating filters fitted to each manifold inlet.

5. A glazes toughening quench system as claimed in Claim 1 c.r- Claim 2 wherein each ejector nozzle can be individually set to discharge a predictable amount of air at a predictable velocity when provided with compressed air at a constant pressure.

A A glass toughening quench system as claimed in Claim 1 or Claim 2 or Claim 5 wherein the air ejector nozzles compressed air discharge aperture profile is designed to ensure that the high velocity discharging compressed air follows an outlet profile into the throat of the nozzle causing a pressure drop towards the nozzle inlet. and entrains a large volume of atmospheric air into the nozzle cap and out through the discharge tube.

7. A glass toughening quench system as claimed in Claiml which has the system air pressure maintained by a bidirectional positional actuator which is capable of being computer controlled,operating a flow control valve.

S. A class toughening quench system as claimed in Claim 1 that utilises stored compressed air to provide the required high volume air flow.

9. An air quench system substantially as described herein with reference to the accompanying drawings "QUENCH NOZZLE DIAGRAM" and "NOZZLE ASSY".

9. A glass toughening quench system substantialy as described herein with reference to the accompanying drawings "QUENCH NOZZLE DIAGRAM" and "NOZZLE ASSY." Amendments to the claims have been filed as follows 1. An air quench system comprising an array of nozzles, each operative to amplify a small amount of high pressure air to generate a flow of cooling air for quenching a glass sheet.

2. An air quench system according to claim 1 in which each nozzle is an air ejector.

3. An air quench system according to claim 1 or claim 2 in which the array comprises a plurality of manifolds each carrying a plurality of nozzles.

4. An air quench system according to any preceding claim in which the nozzles are arranged in the array at a pitch of between 40 and 60mm.

5. An air quench system according to any preceding claim in which compressed air is supplied to the nozzles at a pressure in the range of 7 to 15 bar..

6. An air quench system according to any preceding claim having two arrays of nozzles, each operative to direct air onto a respective surface of a glass sheet.

7. An air quench system substantially as described with reference to the accompanying drawings.

1. An air quench system comprising compressed air ejector nozzles fitted in multiples into manifolds to provide arrays of nozzles set to discharge an even high volume flow of high velocity air along the length of the array. The ability of the nozzles to amplify a small volume of compressed air produces the high volume of lower pressure air required by inducing the flow of atmospheric air through the nozzles. The array sets are assembled in position over and under to provide quenching over the whole area of the load. Each level of arrays (i.e. upper and lower) can be maintained at different pressures to provide adjustment of the rate of quench to each side of the load. During the quench cycle the pressure in the array manifolds is held at the predetermined level by adjusting the main flow control as the stored compressed air pressure decays.The compressed air is replenished during the time that the next load is being heated.

2. An air quench system as claimed in claim 1 utilising individual air ejector nozzles assembled at intervals along a manifold with the discharge tube fitted through the manifold enabling ambient air to be drawn from the one side of the manifold and discharge from the other.

3. An air quench system as claimed in claim 1 or claim 2 that utilises multiple manifolds as required to provide air over any size of area.

4. An air quench system as claimed in claim 1 or claim 2 or claim 3 incorporating filters fitted to each manifold inlet.

5. An air quench system as claimed in claim 1 or claim 2 wherein each ejector nozzle can be individually set to discharge a predictable amount of air at a predictable velocity when provided with compressed air at a constant pressure.

6. An air quench system as claimed in claim 1 or claim 2 or claim 5 wherein the air ejector nozzles compressed air discharge aperture profile is designed to ensure that the high velocity discharging compressed air follows an outlet profile into the throat of the nozzle causing a pressure drop towards the nozzle inlet, and entrains a large volume of atmospheric air into the nozzle cap and out through the discharge tube.

7. An air quench system as claimed in claim 1 which has the system air pressure maintained by a bi-directional positional actuator which is capable of being computer controlled operating a flow control valve.

8. An air quench system as claimed in claim 1 that utilises stored compressed air to provide the required high volume air flow.