CA1203827A - Electric boosting control for a glass forehearth - Google Patents
Electric boosting control for a glass forehearthInfo
- Publication number
- CA1203827A CA1203827A CA000427204A CA427204A CA1203827A CA 1203827 A CA1203827 A CA 1203827A CA 000427204 A CA000427204 A CA 000427204A CA 427204 A CA427204 A CA 427204A CA 1203827 A CA1203827 A CA 1203827A
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- Canada
- Prior art keywords
- glass
- forehearth
- temperature
- circuit
- adjacent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus for heating molten glass flowing through a conditioning section of a forehearth has pairs of electrodes extending through the sidewalls of the forehearth with their ends terminating adjacent the sidewalls and a circuit connect-ed to the electrode pairs and being such as to cause joule effect heating of the glass adjacent the sidewalls of the forehearth, with a source of electrical current connected to the circuit. A first temperature sensor within the fore-hearth at the center line thereof within the conditioning section adjacent an end thereof has a thermocouple immersed in the glass and a second temperature sensor extending into the forehearth adjacent one of the sidewalls thereof in align-ment with the first sensor, a settable, temperature override circuit connected to the circuit means. The second tem-perature sensor is connected to a settable temperature over-ride circuit for adjusting the current to the electrodes to bring the sidewall temperature to the selected set point of the override circuit.
Apparatus for heating molten glass flowing through a conditioning section of a forehearth has pairs of electrodes extending through the sidewalls of the forehearth with their ends terminating adjacent the sidewalls and a circuit connect-ed to the electrode pairs and being such as to cause joule effect heating of the glass adjacent the sidewalls of the forehearth, with a source of electrical current connected to the circuit. A first temperature sensor within the fore-hearth at the center line thereof within the conditioning section adjacent an end thereof has a thermocouple immersed in the glass and a second temperature sensor extending into the forehearth adjacent one of the sidewalls thereof in align-ment with the first sensor, a settable, temperature override circuit connected to the circuit means. The second tem-perature sensor is connected to a settable temperature over-ride circuit for adjusting the current to the electrodes to bring the sidewall temperature to the selected set point of the override circuit.
Description
:12~338Z~7 15~81 In the conditioning and controlling o the tempexature of molten glass flowing through a forehearth, it is typical that such forehearths have a ~eries of gas burners arranged above the level of the glass at either side. The burners have their flames ! directed just above the surface of the glass, the effect of which is to control the amount of heat loss from the glass to the fore-I hearth environment and atmosphere.
It is important that the glass temperature and vis-cosity at the time that it issues from the forehearth be closely con$rolled. The feeding of molten glass from the forehearth is in a stream that is divided into gobs or charges of glass in , glass container manufacturing. In the melting and feeding of colored glass, it is much more difficult to control the tempe-rature because the flame burning over the surface of the glass does not penetrate by radiation and conduction as readily as would be the case ln the feeding of clear or flint glass.
,' The glass entering the forehearth comes from a refiner 20, where its exit temperature is generally controlled so that the temperature of the glass ad~acent the spout of the forehearth may be predicted. On standard gas heated forehearths the glass along the side of the channel runs colder than the glass in the center of the channel. With colored glasses, this normally would lead to a side temperature being 40 to 60 F. cooler than the center line temperature. In some instances, these side-to-center differences in temperature have been as high as 120 F.
This temperature imbalance has a marked effect on the glass ~;
, .
, ~Z6)3~27 distribution in the containers made from khs glass. As pro-duction speeds are increased and the bottle weights are de-creased, the amount of the temperature gradient that can be tolerated becomes crucial.
Typically, thermocouples or other temperature measuring devices immersed in the glass have been used at ~he refiner exit or forehearth entrance. Furthermore, thermocouples have been positioned at various points along the length of the forehearth.
The portion of the forehearth which is ; e~iately next to the spout or fPeder is termed the "csnditioning section" of the forehearth and it is to this section of the forehearth which the ; present invention is specifically addressed.
Electrical heating of glass forehearths, of course, is not a new consideration and, as a recent example, reference may be had to U.S~ Patent 4,227,909 dated October 14, 1980 and issued in the name of ~ornyak, Jr., et al. This particular patent dis-closes an arrangement for proviaing joule effect heating across the ch~nnel of the forehearth by positioning of the electrodes of opposite polarities on opposite sides of ~he forehearth. In addition, the patent teaches an arrangement for assuring that all of the electrodes in the forehearth are kept at the same electrical potential relative to a counter-electrode immersed in the glass melter.
Another patent recently issued, U.S. Patent No.
25! 4~247,733 to Sevenson dated January 27, 19~1, discloses an electrically heated glass forehearth in which the electrodes i appear to extend acro~s the full width of the forehearth, with adjacent electrodes being of di~ferent polarity to provide a ,:
It is important that the glass temperature and vis-cosity at the time that it issues from the forehearth be closely con$rolled. The feeding of molten glass from the forehearth is in a stream that is divided into gobs or charges of glass in , glass container manufacturing. In the melting and feeding of colored glass, it is much more difficult to control the tempe-rature because the flame burning over the surface of the glass does not penetrate by radiation and conduction as readily as would be the case ln the feeding of clear or flint glass.
,' The glass entering the forehearth comes from a refiner 20, where its exit temperature is generally controlled so that the temperature of the glass ad~acent the spout of the forehearth may be predicted. On standard gas heated forehearths the glass along the side of the channel runs colder than the glass in the center of the channel. With colored glasses, this normally would lead to a side temperature being 40 to 60 F. cooler than the center line temperature. In some instances, these side-to-center differences in temperature have been as high as 120 F.
This temperature imbalance has a marked effect on the glass ~;
, .
, ~Z6)3~27 distribution in the containers made from khs glass. As pro-duction speeds are increased and the bottle weights are de-creased, the amount of the temperature gradient that can be tolerated becomes crucial.
Typically, thermocouples or other temperature measuring devices immersed in the glass have been used at ~he refiner exit or forehearth entrance. Furthermore, thermocouples have been positioned at various points along the length of the forehearth.
The portion of the forehearth which is ; e~iately next to the spout or fPeder is termed the "csnditioning section" of the forehearth and it is to this section of the forehearth which the ; present invention is specifically addressed.
Electrical heating of glass forehearths, of course, is not a new consideration and, as a recent example, reference may be had to U.S~ Patent 4,227,909 dated October 14, 1980 and issued in the name of ~ornyak, Jr., et al. This particular patent dis-closes an arrangement for proviaing joule effect heating across the ch~nnel of the forehearth by positioning of the electrodes of opposite polarities on opposite sides of ~he forehearth. In addition, the patent teaches an arrangement for assuring that all of the electrodes in the forehearth are kept at the same electrical potential relative to a counter-electrode immersed in the glass melter.
Another patent recently issued, U.S. Patent No.
25! 4~247,733 to Sevenson dated January 27, 19~1, discloses an electrically heated glass forehearth in which the electrodes i appear to extend acro~s the full width of the forehearth, with adjacent electrodes being of di~ferent polarity to provide a ,:
-2-12V38Z'7 joule e~fect heating current therebetween These electrodes are such as to divide the forehearth into a plurality of individual zones under separa-te control.
The present invention provides apparatus for heat-ing molten glass flowing through a conditioning section o a forehearth comprising, a plurality of pairs of electrodes e~tending through sidewalls of the forehearth with their ends terminating adjacent the sidewalls thereof, circuit means connected to the electrode pairs, the circuit means being such as to cause joule effect heating of the glass adjacent the sidewalls of the forehearth, a source of electri-cal current connected to the circuit means, a first tempera-ture sensing means positioned within the forehearth at the center line thereof within the conditioning section adjacent an end thereof, the first sensing means including a thermo-couple immersed in the glass, a second temperature sensing means extending into the forehearth adjacent one of the side-walls thereof in alignment with the first sensing means, a current controller in the circuit means, a settable, tempera-ture override circuit connected to the circuit means, and means connecting the second temperature sensing to the over-ride circuit for adjusting the current to the electrodes to bring the sidewall temperature to the selected set point of the override circuit.
It should be understood that other heat is applied to the forehearth by gas combustion in the usual manner and that the present invention, generallv speaking, could be considered a front-end boosting by electric heat. In ~ .
~2~)3~3Z7 addition, the present invention provides a system in which a set current level selected by the operator may be applied ko elec-trodes positioned in the conditioning sectlon. These electrodes and the setting will provide a certain degree of boosting temperature to the sides of the forehearth. In a preferred embodiment, tri-level thermocouples or thermo-couples along the center line of the forehearth adjacent the spout at three levels will monitor the temperature of the glass at these three levels. The second temperature sensing device provides a signal to the override circuit, which has a settable temperature indicator which may be in digital form. The operator may set the temperature desired and the override circuit, in response to the sidewall tempera-ture, will provide additional current to the system for bring-ing the sidewall temperature up to the set point temperature.In this manner, sidewall temperature may be brought into agreement with the center line temperature, thus providing glass controlled to the optimum condition for glass container forming.
- 3a ~
/
~2V3~327 BRIEF DESCRIP~ION OF THE DRAWIN~S
EIG. 1 ls a schematic plan view oE the conditioning section of a forehearth embodyin the present invention, with A
schematic electrical circuit arrangement and control therefor;
FIG. 2 is a cross-sectional view taken at line 2-2 o~ FIG. l; and FIG 3 is a cross-sectional view taken at line 3-3 of ~IG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
With particular reference to FIG. 1, there is shown the conditioning section of a forehearth. This section of the forehearth comprises a ceramic channel 11 shown in cross-section in FIG. 3. The channel 11 is generally of parallel sidewall configuration extending from the 15- refiner until reaching a point 12 where the sidewalls begin to converge toward each other. At the forwardmost end of the channel 11, where the converging sidewalls reach their closest extent, is where a feeder, or what is frequently termed a "spout"
13 is fixed. The spout 13 generally takes the form of a semi-~O circular metal member 14 li~ed with heat resistant fire brick 15.The spout has a circular opening 16 in the bottom thereof. This opening will be closed by a ceramic member 8 having downwardly converging flow channels for providing one or more streams of glass which may be cut into one or more discrete mold charges.
The member 8, closing the opening 16 is conventional in the art and a detailed description thereof is not believed necessary.
Suffice it to say that this member termed in the art as a "ceramic feeder orifice" is supported in an orifice pan normally ,i ,:, ;
~;~U38;27 hinged to the f~eder bowl so as to be movable up into position or away from the position of the opening 16.
Concentric above the opening 16 is a cyl~ndrical tube 17 termed a "feeder tube". This member is rotated about its vertical axis and serves to circulate the glass around the out-side thereof to equaiize the temperature of the glass in the , feeder. Furthermore, the lower end of the tube 17 is positioned relative to the upper edge of ~he opening 16 so as to control I the flow rate of glass from the forehearth through the opening 10 ~ 16. In a typical forehearth where charges or gobs of glass are formed for delivery to bottle forming machines, a vertical plunger will be positioned within the tube 17 and the plunger will be reciprocated vertically to, in effect, extrude the glass I in one or more streams and upon raising of the plunger, have the effect of stopping the flo~ of glass, at which time the extruded glass is cut into a discrete charge with shears. This cycle repeats itself so that discrete mold charges are fed from the feeder 13 and then fall by gravity to the forming machine.
~, As shown in FIG 2, the feeder 13 may and typically 20 ' does have one or more gas burners 18 around the periphery there-of for keeping the surface of the glass in the spout or feeder at a stable temperature.
In forehearths of the type shown in PIGS. 1-3, the forehearth channel 11 is covered by a ceramic roof 19 made of a plurality of fire bricks 20. Mormally, this roo~ is uninter-rupted; however, as can be seen in FI~S. 2 and 3, three access ~ holes 21, 22 and 23 are provided through the roof 19. Through i each hole or openiny extends a te~perature sensing device 24.
i:
1~03827 As can best be seen in FIG. 3, there are three ~uch devices, as shown in E'IG. 2 and each tempera-ture sensin~ device i~
composed of a support member supporting three separate and distinct thermocouples 26, 27 and 28.
S ~he upper thermocouple is numbered 26, the middle thermocouple 27, and the bottom or lowest thermocouple i5 designated 28. Each of the temperature sensing devices is commonly referred to as a "tri-level thermo-couple". However, basically, it is a temperature sensing device having three vertically spaced thermocouples carried there-by. While three couples are shown, obviously, more could be used if desired.
In the present situation, where the glass in the fore-hearth enters the conditioning section at approximately six inches in depth, the individual thermocouples or sensing elements of the "tri-level" may be at one inch, three inches and five i inches,respectively,from the bottom of the channel. Thus lt can be seen that the thermocouples all are immersed in the molten ~ stream of glass and will sense the actual temperature of the glass at the position thereof.
It has been applicants' experience that, in the operation of a forehearth, it is desirable to have the center line "tri-level" thermocouple sensing elements all at as close to the same temperature as is possible. ~he control to achieve such a condition, by and large, must be effected by adjusting the temperature of the glass issuing from the refiner, with any additional heat, due to surface radiation, being prevented or compensated for by the firing of the gas burners along the sides of the channel prior to the glass arriving at the conditioning ~2~)38~
152~1 section of the forehearth. In some cases, the glass may be runniny too hot at the bottom of the center line which may necessitate cooling the bottom glass of the forehearth.
Obviously, anytime it is necessary to provide extra cooling in the forehearth in order to achieve a temperature balance, some fuel is being wasted. The ideal condition would be the arrival of the glass at the tri-level thermocouple with all three couples registering the same ideal temperature for the glass composition being melted.
10 ' As previously stated, it is well known that the glass along the sides of the forehearth channel at the conditioning section tends to be 20 to 40 cooler than the glass at the center line of the forehearth. With this in mind, a plurality of electrodes 29 extending through the sidewall of the channel ll ,. , are provided and have their ends immersed in the molten glass to approximately three inches~ As can be seen, the adjacent elect-¦ rodes are of opposite polarity, while opposed electrodes are ofthe same polarity, thus the major portion of the current flows between adjacent electrodes and only a minor portion will flow 20 1 across the channel to any significant degree. Joule effect heat-ing then occurs principally along the sidewall and only in the ; conditioning section in advance of the feeder or spout. The exact ratio of current flowing between adjacent electrodes versus opposite electrodes is a function of the relative spacing.
The electrodes are connected to a transformer 30 which in turn is connected to a current control device 31 and thence to a source of current. The current control device 31 is of the type that may be preset by the operator to some preselected current level. The current level chosen will be that believed to be sufficient to maintain the sidewall temperature and the centerline at a fairly close level.
38~,'7 All of the thermocouples 26, 27 and 2~ in the center of the temperature ~ensing device 24 are connected by a lead 32 to a temperature indicator 33. Likewise, the three thermocouple associated with the right side thermo~ouple mounted in the hole 5, 23 are connected by a lead 34 to the lndicator 33. Ind~cator 33 may be a multi-channel temperature mea~uring deviae such a~ a Doric digital ~eadout device sold by Do~ic In~trument Company.
This instrument may provide visual readings of all of the thermo-couples and, if desired, may provide recordings of these readings over a period of time. The readings given by the indicator 33 may influence the setting of the current control 31 by the operator and al50 provide a tool for the operator to use in sett-ing up the glass temperature as it enters the forehearth.
The temperature sensing device mounted in the hole 21 to the left siae, as viewed in FIG. 3, has its middle thermo-couple connected by a lead 25 to an override circuit 36. The override circuit 36 is provided ~ith a set point temperature scale 37 that may be selected by the operator and typically would be selecte~ to be the s~me t~mperature reading as that of the ce~ter line of the forehearth. The o~erride circuit, in response to deviations o~ the sidewall thermocouple readings~will provide current adju~tment to the current to the transformer 30 and this control is automatic. Thus, the overriae circuit will adjust the current to the electrodes so as to bring the sidewall temperature 25j of the forehearth up to the center line tem~erature, or the '~ temperature which is placed in the ~et point temperature scale 37 In this manner the temperature imbalance, which has a marked "
' -8-- , .... _ ~2~3~
. .
effect on glass distribution in bottles foxmed by the glass from the forehearth, i8 obviated and the system will provide fxont end boosting of the temperature and resulk in incxeased job efficiency and improved quality o~ ware.
., g _ .,
The present invention provides apparatus for heat-ing molten glass flowing through a conditioning section o a forehearth comprising, a plurality of pairs of electrodes e~tending through sidewalls of the forehearth with their ends terminating adjacent the sidewalls thereof, circuit means connected to the electrode pairs, the circuit means being such as to cause joule effect heating of the glass adjacent the sidewalls of the forehearth, a source of electri-cal current connected to the circuit means, a first tempera-ture sensing means positioned within the forehearth at the center line thereof within the conditioning section adjacent an end thereof, the first sensing means including a thermo-couple immersed in the glass, a second temperature sensing means extending into the forehearth adjacent one of the side-walls thereof in alignment with the first sensing means, a current controller in the circuit means, a settable, tempera-ture override circuit connected to the circuit means, and means connecting the second temperature sensing to the over-ride circuit for adjusting the current to the electrodes to bring the sidewall temperature to the selected set point of the override circuit.
It should be understood that other heat is applied to the forehearth by gas combustion in the usual manner and that the present invention, generallv speaking, could be considered a front-end boosting by electric heat. In ~ .
~2~)3~3Z7 addition, the present invention provides a system in which a set current level selected by the operator may be applied ko elec-trodes positioned in the conditioning sectlon. These electrodes and the setting will provide a certain degree of boosting temperature to the sides of the forehearth. In a preferred embodiment, tri-level thermocouples or thermo-couples along the center line of the forehearth adjacent the spout at three levels will monitor the temperature of the glass at these three levels. The second temperature sensing device provides a signal to the override circuit, which has a settable temperature indicator which may be in digital form. The operator may set the temperature desired and the override circuit, in response to the sidewall tempera-ture, will provide additional current to the system for bring-ing the sidewall temperature up to the set point temperature.In this manner, sidewall temperature may be brought into agreement with the center line temperature, thus providing glass controlled to the optimum condition for glass container forming.
- 3a ~
/
~2V3~327 BRIEF DESCRIP~ION OF THE DRAWIN~S
EIG. 1 ls a schematic plan view oE the conditioning section of a forehearth embodyin the present invention, with A
schematic electrical circuit arrangement and control therefor;
FIG. 2 is a cross-sectional view taken at line 2-2 o~ FIG. l; and FIG 3 is a cross-sectional view taken at line 3-3 of ~IG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
With particular reference to FIG. 1, there is shown the conditioning section of a forehearth. This section of the forehearth comprises a ceramic channel 11 shown in cross-section in FIG. 3. The channel 11 is generally of parallel sidewall configuration extending from the 15- refiner until reaching a point 12 where the sidewalls begin to converge toward each other. At the forwardmost end of the channel 11, where the converging sidewalls reach their closest extent, is where a feeder, or what is frequently termed a "spout"
13 is fixed. The spout 13 generally takes the form of a semi-~O circular metal member 14 li~ed with heat resistant fire brick 15.The spout has a circular opening 16 in the bottom thereof. This opening will be closed by a ceramic member 8 having downwardly converging flow channels for providing one or more streams of glass which may be cut into one or more discrete mold charges.
The member 8, closing the opening 16 is conventional in the art and a detailed description thereof is not believed necessary.
Suffice it to say that this member termed in the art as a "ceramic feeder orifice" is supported in an orifice pan normally ,i ,:, ;
~;~U38;27 hinged to the f~eder bowl so as to be movable up into position or away from the position of the opening 16.
Concentric above the opening 16 is a cyl~ndrical tube 17 termed a "feeder tube". This member is rotated about its vertical axis and serves to circulate the glass around the out-side thereof to equaiize the temperature of the glass in the , feeder. Furthermore, the lower end of the tube 17 is positioned relative to the upper edge of ~he opening 16 so as to control I the flow rate of glass from the forehearth through the opening 10 ~ 16. In a typical forehearth where charges or gobs of glass are formed for delivery to bottle forming machines, a vertical plunger will be positioned within the tube 17 and the plunger will be reciprocated vertically to, in effect, extrude the glass I in one or more streams and upon raising of the plunger, have the effect of stopping the flo~ of glass, at which time the extruded glass is cut into a discrete charge with shears. This cycle repeats itself so that discrete mold charges are fed from the feeder 13 and then fall by gravity to the forming machine.
~, As shown in FIG 2, the feeder 13 may and typically 20 ' does have one or more gas burners 18 around the periphery there-of for keeping the surface of the glass in the spout or feeder at a stable temperature.
In forehearths of the type shown in PIGS. 1-3, the forehearth channel 11 is covered by a ceramic roof 19 made of a plurality of fire bricks 20. Mormally, this roo~ is uninter-rupted; however, as can be seen in FI~S. 2 and 3, three access ~ holes 21, 22 and 23 are provided through the roof 19. Through i each hole or openiny extends a te~perature sensing device 24.
i:
1~03827 As can best be seen in FIG. 3, there are three ~uch devices, as shown in E'IG. 2 and each tempera-ture sensin~ device i~
composed of a support member supporting three separate and distinct thermocouples 26, 27 and 28.
S ~he upper thermocouple is numbered 26, the middle thermocouple 27, and the bottom or lowest thermocouple i5 designated 28. Each of the temperature sensing devices is commonly referred to as a "tri-level thermo-couple". However, basically, it is a temperature sensing device having three vertically spaced thermocouples carried there-by. While three couples are shown, obviously, more could be used if desired.
In the present situation, where the glass in the fore-hearth enters the conditioning section at approximately six inches in depth, the individual thermocouples or sensing elements of the "tri-level" may be at one inch, three inches and five i inches,respectively,from the bottom of the channel. Thus lt can be seen that the thermocouples all are immersed in the molten ~ stream of glass and will sense the actual temperature of the glass at the position thereof.
It has been applicants' experience that, in the operation of a forehearth, it is desirable to have the center line "tri-level" thermocouple sensing elements all at as close to the same temperature as is possible. ~he control to achieve such a condition, by and large, must be effected by adjusting the temperature of the glass issuing from the refiner, with any additional heat, due to surface radiation, being prevented or compensated for by the firing of the gas burners along the sides of the channel prior to the glass arriving at the conditioning ~2~)38~
152~1 section of the forehearth. In some cases, the glass may be runniny too hot at the bottom of the center line which may necessitate cooling the bottom glass of the forehearth.
Obviously, anytime it is necessary to provide extra cooling in the forehearth in order to achieve a temperature balance, some fuel is being wasted. The ideal condition would be the arrival of the glass at the tri-level thermocouple with all three couples registering the same ideal temperature for the glass composition being melted.
10 ' As previously stated, it is well known that the glass along the sides of the forehearth channel at the conditioning section tends to be 20 to 40 cooler than the glass at the center line of the forehearth. With this in mind, a plurality of electrodes 29 extending through the sidewall of the channel ll ,. , are provided and have their ends immersed in the molten glass to approximately three inches~ As can be seen, the adjacent elect-¦ rodes are of opposite polarity, while opposed electrodes are ofthe same polarity, thus the major portion of the current flows between adjacent electrodes and only a minor portion will flow 20 1 across the channel to any significant degree. Joule effect heat-ing then occurs principally along the sidewall and only in the ; conditioning section in advance of the feeder or spout. The exact ratio of current flowing between adjacent electrodes versus opposite electrodes is a function of the relative spacing.
The electrodes are connected to a transformer 30 which in turn is connected to a current control device 31 and thence to a source of current. The current control device 31 is of the type that may be preset by the operator to some preselected current level. The current level chosen will be that believed to be sufficient to maintain the sidewall temperature and the centerline at a fairly close level.
38~,'7 All of the thermocouples 26, 27 and 2~ in the center of the temperature ~ensing device 24 are connected by a lead 32 to a temperature indicator 33. Likewise, the three thermocouple associated with the right side thermo~ouple mounted in the hole 5, 23 are connected by a lead 34 to the lndicator 33. Ind~cator 33 may be a multi-channel temperature mea~uring deviae such a~ a Doric digital ~eadout device sold by Do~ic In~trument Company.
This instrument may provide visual readings of all of the thermo-couples and, if desired, may provide recordings of these readings over a period of time. The readings given by the indicator 33 may influence the setting of the current control 31 by the operator and al50 provide a tool for the operator to use in sett-ing up the glass temperature as it enters the forehearth.
The temperature sensing device mounted in the hole 21 to the left siae, as viewed in FIG. 3, has its middle thermo-couple connected by a lead 25 to an override circuit 36. The override circuit 36 is provided ~ith a set point temperature scale 37 that may be selected by the operator and typically would be selecte~ to be the s~me t~mperature reading as that of the ce~ter line of the forehearth. The o~erride circuit, in response to deviations o~ the sidewall thermocouple readings~will provide current adju~tment to the current to the transformer 30 and this control is automatic. Thus, the overriae circuit will adjust the current to the electrodes so as to bring the sidewall temperature 25j of the forehearth up to the center line tem~erature, or the '~ temperature which is placed in the ~et point temperature scale 37 In this manner the temperature imbalance, which has a marked "
' -8-- , .... _ ~2~3~
. .
effect on glass distribution in bottles foxmed by the glass from the forehearth, i8 obviated and the system will provide fxont end boosting of the temperature and resulk in incxeased job efficiency and improved quality o~ ware.
., g _ .,
Claims (6)
1. Apparatus for heating molten glass flowing through conditioning section of a forehearth comprising:
a plurality of pairs of electrodes extending through sidewalls of the forehearth with their ends terminating.
adjacent the sidewalls thereof;
circuit means connected to said electrode pairs, said circuit means being such as to cause joule effect heating of the glass adjacent the sidewalls of the forehearth;
a source of electrical current connected to said circuit means;
a first temperature sensing means positioned within said forehearth at the center line thereof within the condition-ing section adjacent an end thereof, said first sensing means including a thermocouple immersed in the glass;
a second temperature sensing means extending into the forehearth adjacent one of the sidewalls thereof in alignment with said first sensing means;
a current controller in said circuit means;
a settable, temperature override circuit connected to said circuit means; and means connecting said second temperature sensing to said override circuit for adjusting the current to said elect-rodes to bring the sidewall temperature to the selected set point of said override circuit.
a plurality of pairs of electrodes extending through sidewalls of the forehearth with their ends terminating.
adjacent the sidewalls thereof;
circuit means connected to said electrode pairs, said circuit means being such as to cause joule effect heating of the glass adjacent the sidewalls of the forehearth;
a source of electrical current connected to said circuit means;
a first temperature sensing means positioned within said forehearth at the center line thereof within the condition-ing section adjacent an end thereof, said first sensing means including a thermocouple immersed in the glass;
a second temperature sensing means extending into the forehearth adjacent one of the sidewalls thereof in alignment with said first sensing means;
a current controller in said circuit means;
a settable, temperature override circuit connected to said circuit means; and means connecting said second temperature sensing to said override circuit for adjusting the current to said elect-rodes to bring the sidewall temperature to the selected set point of said override circuit.
2. The apparatus of claim 1 wherein said first temperature sensing means is a tri-level thermocouple.
3. The apparatus of claim 2 wherein the tri-level thermocouple has a first couple adjacent the surface but im-mersed in the glass and two other couples at deeper levels in the glass.
4. The apparatus of claim 1, 2 or 3, wherein said second temperature sensing means is a thermocouple immersed in the glass at approximately mid-depth thereof.
5. The apparatus of claim 1 wherein said second temperature sensing means is a tri-level thermocouple having couples at three levels in the glass with the center couple being connected to the override circuit.
6. The apparatus of claim 3 further including a temperature indicator and means for connecting all of the couples to the indicator to obtain a reading of the temperature at the three levels.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000427204A CA1203827A (en) | 1983-05-02 | 1983-05-02 | Electric boosting control for a glass forehearth |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000427204A CA1203827A (en) | 1983-05-02 | 1983-05-02 | Electric boosting control for a glass forehearth |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1203827A true CA1203827A (en) | 1986-04-29 |
Family
ID=4125145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000427204A Expired CA1203827A (en) | 1983-05-02 | 1983-05-02 | Electric boosting control for a glass forehearth |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1203827A (en) |
-
1983
- 1983-05-02 CA CA000427204A patent/CA1203827A/en not_active Expired
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