GB1603687A - Fore-hearth control system - Google Patents

Fore-hearth control system Download PDF

Info

Publication number
GB1603687A
GB1603687A GB2272578A GB2272578A GB1603687A GB 1603687 A GB1603687 A GB 1603687A GB 2272578 A GB2272578 A GB 2272578A GB 2272578 A GB2272578 A GB 2272578A GB 1603687 A GB1603687 A GB 1603687A
Authority
GB
United Kingdom
Prior art keywords
zone
forehearth
transformer
current
time
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.)
Expired
Application number
GB2272578A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BOULTING Ltd W
Original Assignee
BOULTING Ltd W
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by BOULTING Ltd W filed Critical BOULTING Ltd W
Priority to GB2272578A priority Critical patent/GB1603687A/en
Publication of GB1603687A publication Critical patent/GB1603687A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
    • G05D23/2401—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor using a heating element as a sensing element
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B7/00—Distributors for the molten glass; Means for taking-off charges of molten glass; Producing the gob, e.g. controlling the gob shape, weight or delivery tact
    • C03B7/02—Forehearths, i.e. feeder channels
    • C03B7/06—Means for thermal conditioning or controlling the temperature of the glass
    • C03B7/07—Electric means
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/0019—Circuit arrangements
    • H05B3/0023—Circuit arrangements for heating by passing the current directly across the material to be heated

Description

(54) FOREHEARTH CONTROL SYSTEM (71) We, W. A. BOULTING LIMT- TED, a British Companv, of Chapel Road, Penketh, Warrington, WA5 2PL, Cheshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to an electric forehearth for conveying molten material from a furnace to, for example, a forming station, and to a method of operating such a forehearth.
In particular the present invention relates to an electric forehearth for use in conveying an electrically conductive material when in a flowable state, the electrical resistance of the material being inversely proportional to its temperature at least over a specific temperature range. The following text makes reference forehearth it loses heat. However, as present invention is equally well applicable to the production of any electrically conductive material, particularly when in a molten state.
In the production of glass, the molten glass leaves the furnace and flows along a forehearth, i.e. a refractory channel, to a forming machine. As the molten glass flows along the forehearth it loses heat. However, as the temperature gradients within the glass have a direct bearing upon the usable percentage of the glass produced, the heat losses and thus these temperature gradients must be controlled. In the hollow ware and glass container industries, the degree to which tem- perature control can be achieved has a direct bearing upon the size, weight and homogeneity of the 'gob' (i.e. the lump of glass which drops from the forehearth to the forming machine). It is these factors which, together with the temperature gradient in the 'gob', determine whether the finished product will be useful or rejected.
In known glass production forehearths it is known to use various forms of heating means along the length of the forehearth to reduce heat losses and control the temperature gradients. However, the present invention particularly relates to forehearths which incorporate heating means in the form of heating electrodes which project actually into the molten glass. When heating electrodes are used, a current is passed between pairs of electrodes through the glass, the inherent electrical resistance of the glass causing the glass to be heated by the current.
To control the heating current the actual temperature of the glass must be known and temperature measurement has hitherto been based upon sensing devices such as thermo couples or radiation sensors. However, these sensing devices only give a temperature indi cation relative to the extremely small area or mass to which they are applied and it has been found that even with conscientious and accurate adjustment of the heating means in dependence upon the temperature measured; unsensed undesirable temperature gradients can occur which may result in an undesirable proportion of defects in the finished product.
It is an aim of the present invention to provide a method and apparatus which is suitable for use in, for example, glass production, the temperature of the material flowing along the forehearth being accurately monitored and controlled.
According to the present invention there is provided an electric forehearth for conveying molten material from a furnace to a forming station, said forehearth comprising an elongate channel which is divided transversely into at least two zones for the sake of temperature control, at least one pair of heating electrodes projecting into the channel in each zone, the electrodes of each zone being connected to a respective transformer regulator which is controllable by a constant current controller, each constant current controller being arranged to monitor the current flowing between the heating electrodes in a zone and to adjust the particular transformer regulator connected thereto, to seek to maintain a predetermined current value, a control circuit being adapted to disconnect the constant current controller which monitors the heating current in one of said zones, from the transformer regulator for that zone, for a predetermined period of time, whilst allowing the or each other constant current controller to monitor and control the current in the or each other zone, and to reconnect the constant current controller to the transformer regulator for said one zone for a subsequent shorter predetermined period of time, whilst disconnecting the transformer regulator and constant current controller for the or each other zone from the heating electrods in the or each other zone, for said shorter predetermined time.
Thus by utilising a forehearth constructed according to the present invention, tiie resistance, i.e. temperature, of the flowable material at a particular zone, can be quickly and easily measured and the electric current adjusted to try to produce the desired temperature in that zone whilst the transformer regulators and constant current controllers are disconnected from the other zones. In this manner the temperature measurement is accurate as there are no influences from currents or transformer regulator winding impedances in other zones, as has been the case in previous arrangements wherein all of the zone temperatures are continuously monitored and adjusted.
It has been found in practice that a change in temperature from the furnace of more than 1"C per five minute period is virtually impossible. However, a correction in the electric current in a zone to achieve a change of 1 C can be effected by the controller and regulator in a matter of a few seconds. Bearing these facts in mind the control circuit of a preferred embodiment of the present invention is adapted to operate on a five minute repeat cycle. For four minutes and fiftv-five seconds the or each other zone is monitored and the temperature thereof continuously adjusted, whilst a constant voltage is applied to said one zone whatever the current flowing, the constant current controller being disconnected from the transformer regulator of this zone.
For the remaining five seconds of the five minute repeat cycle, the transformer regulators and constant current controllers associated with said other zone or zones are disconnected therefrom and the constant current controller for said one zone is connected to the transformer regulator for that one zone. The current passing through said one zone is the only current passing through the whole of the flowable material, all other influences having been removed for the five-second period, and thus an accurate measurement and correction, of the current, i.e. temperature, in said one zone can be achieved.
In one embodiment of the present invention the forehearth is divided into four contiguous zones for the purposes of temperature control, each zone having a plurality of electrode pairs coupled to a transformer regulator and constant current controller. Preferably, both in this embodiment and all other possible embodiments of the present invention, the zone at the upstream end of the forehearth is the zone which is adjusted only during the said shorter predetermined period of time.
Any number of zones may be provided for and also the predetermined periods of time together with the time cycle of the control circuit may be selected as desired.
According to a further aspect of the present invention there is provided a method of controlling an electric forehearth, the forehearth comprising an elongate channel which is divided transversely into at least two zones for the sake of temperature control, at least one pair of heating electrodes projecting into the channel in each zone and being connectible to a transformer regulator and constant current controller in a control circuit, said method comprising the steps of maintaining, for a predetermined period of time, a constant voltage across electrodes in one zone whilst both constantly monitoring the electric current passing between electrodes in the or each other zone and adjusting the voltage thereacross to maintain a substantially constant current therebetween, and, for a subsequent shorter predetermined period of time, monitoring the current passing between the electrodes of said one zone and adjusting the transformer regulator to achieve a predetermined current value through this zone. the electrodes of the or each other zone being disconnected from current and voltage sources for this subsequent shorter predetermined period of time, these steps being sequentially and continuously repeated as desired.
The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic plan view of one embodiment of a forehearth constructed according to the present invention having four zones, Fig. 2 shows part of the control circuit applied to each zone in Fig. 1; and Fig. 3 is a schematic circuit diagram for a control circuit for use with the forehearth of Figs. 1 and 2.
The forehearth illustrated schematically in the accompanying drawings is constructed according to the present invention and basically comprises an elongate channel 1 constructed of heat resistant material e.g. fire brick, heating electrodes 2 extending into the channel 1 transversely of the longitudinal axis of the channel. The heating electrodes are connected in groups in four different adjacent zones, i.e. Zone 1, Zone 2, Zone 3 and Zone 4, arranged along the length of the channel 1, the group of electrodes on each side of the channel 1 in any one zone being connected to terminals 3 and 4 in the circuitry shown in Fig. 2. This circuitry basically comprises for each zone a transformer regulator 5 and a constant current controller 6, details of which components have been omitted as they are commonly known in the electronics art.Transformer regulator 5 is connected across the groups of electrodes in a zone and applies voltage thereacross, causing a current to flow in that zone through the electrically conductive material flowing along the forehearth in the direction A, the size of the current being dependent upon the electrical resistance, and thus the temperature, of the material flowing along the forehearth. The current flowing is monitored via a current transformer 7 which is connected to constant current controller 6, the constant current controller being connected via auxiliary relay contacts AR/4, AR/5, AR/6, or AR7, to transformer regulator 5.Thus transformer regulator 5 is continuously adjusted by means of the constant current controller, when auxiliarv relay contacts AR/4, AR/5, AR/6 or AR/7 are closed, to maintain a substantially constant current flowing through the material passing through the particular zone.
Each transformer regulator 5 can be isolated from the heating electrodes 2 by a contractor C, the contactors C being connected into the control circuit illustrated in Fig. 3. The control circuit also includes an impulse timer 8 arranged to control time switch 9 and thus auxiliary relay 10. Auxiliary relay contacts AR/1, AR/2 and AR/3 are also connected in the control circuit to control the contactors C of the transformer regulators of the three downstream zones of the forehearth having regard to the direction of flow A, i.e. Zones 2, 3 and 4.
The impulse timer 8 has a repeat time of five minutes and the time switch 9 is arranged to be closed for 4 minutes 55 seconds and open for 5 seconds during each repeat cycle.
In an alternative arrangement the repeat time may be divided differently or a different repeat time may be chosen and this may be divided as desired. During the 4 minute 55 seconds period of the repeat time with time switch 9 closed, the auxiliary relay 10 is energised thereby closing all of the AR contacts, except for AR/4 which open; the AR/4 contacts being associated with Zone 1. Thus, as can be seen from Fig. 3, all of the contactors C are closed connecting the transformer regulators to the heating electrodes in all of the zones, and with contacts AR/5, AR/6 and AR/7 closed, the constant current controllers adjust the transformer regulators for Zones 2, 3 and 4 to maintain the current passing therethrough, constant.However, as contacts AR/4 are open at this time the voltage output of the transformer regulator for Zone l remains constant, the current passing through the material in this Zone 1 varying with the temperature, i.e. resistance, of the material.
At the end of the 4 minutes 55 seconds period of time, the time switch 9 open deenergising auxiliary relay 10 and opening contacts AR/1, AR/2, AR/3, AR/5, AR/6 and AR/7, whilst closing contacts AR/4. Thus the contactors C for zones 2, 3 and 4 are opened isolating the transformer regulators 5 from the heating electrodes 2 in these zones, and the constant current controllers 6 are isolated from the transformer regulators for these zones, preventing any incorrect adjustment of the transformer regulators when the controllers 6 sense zero current flow.However, the contactor for Zone 1 remains closed and, with contacts AR/4 also closed, the transformer regulator and constant current controller for Zone 1 measure the current flowing through the material in Zone 1, this current being dependent upon the resistance and hence upon the temperature of this material. When the temperature of the material flowing through Zone 1 deviates from the desired value, its resistance varies correspondingly and hence the current will vary from its set-point. The controller then adjusts the voltage via the regulator to again achieve the desired current and hence to regain the desired temperature.
This regulating action takes place within the 5 seconds the time switch 9 is open, the time switch then closing to once again maintain a constant voltage across Zone 1 whilst measuring and adjusting the current passing through Zones 2, 3 and 4. This process is continuously repeated whilst the forehearth is in use, tile temperature of the material in upstream Zone 1 being measured and a corrective adjustment being made during the 5 second period in each 5 minute repeat time. During this 5 second period no other currents pass through the material in the forehearth other than the current through Zone 1. Thus an accurate temperature measurement in Zone 1 is possible with no external external influences, an accurate adjustment being thus possible to attain the desired temperature in Zone 1.
Having attained a desired temperature in Zone 1 minor corrections are only necessary in the downstream zones of the forehearth.
Thus by virtue of the present invention a forehearth is provided which has a high degree of temperature control, based on accurate temperature measurement and adjustment, providing for optimum quality of the material, e.g. glass, flowing therealong.
WHAT WE CLAIM IS: 1. An electric forehearth for conveying molten material from a furnace to a forming station, said forehearth comprising an elongate channel which is divided transversely into at least two zones for the sake of temperature control, at least one pair of heating electrodes projecting into the channel in each zone, the
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. shown in Fig. 2. This circuitry basically comprises for each zone a transformer regulator 5 and a constant current controller 6, details of which components have been omitted as they are commonly known in the electronics art. Transformer regulator 5 is connected across the groups of electrodes in a zone and applies voltage thereacross, causing a current to flow in that zone through the electrically conductive material flowing along the forehearth in the direction A, the size of the current being dependent upon the electrical resistance, and thus the temperature, of the material flowing along the forehearth.The current flowing is monitored via a current transformer 7 which is connected to constant current controller 6, the constant current controller being connected via auxiliary relay contacts AR/4, AR/5, AR/6, or AR7, to transformer regulator 5. Thus transformer regulator 5 is continuously adjusted by means of the constant current controller, when auxiliarv relay contacts AR/4, AR/5, AR/6 or AR/7 are closed, to maintain a substantially constant current flowing through the material passing through the particular zone. Each transformer regulator 5 can be isolated from the heating electrodes 2 by a contractor C, the contactors C being connected into the control circuit illustrated in Fig. 3. The control circuit also includes an impulse timer 8 arranged to control time switch 9 and thus auxiliary relay 10. Auxiliary relay contacts AR/1, AR/2 and AR/3 are also connected in the control circuit to control the contactors C of the transformer regulators of the three downstream zones of the forehearth having regard to the direction of flow A, i.e. Zones 2, 3 and 4. The impulse timer 8 has a repeat time of five minutes and the time switch 9 is arranged to be closed for 4 minutes 55 seconds and open for 5 seconds during each repeat cycle. In an alternative arrangement the repeat time may be divided differently or a different repeat time may be chosen and this may be divided as desired. During the 4 minute 55 seconds period of the repeat time with time switch 9 closed, the auxiliary relay 10 is energised thereby closing all of the AR contacts, except for AR/4 which open; the AR/4 contacts being associated with Zone 1. Thus, as can be seen from Fig. 3, all of the contactors C are closed connecting the transformer regulators to the heating electrodes in all of the zones, and with contacts AR/5, AR/6 and AR/7 closed, the constant current controllers adjust the transformer regulators for Zones 2, 3 and 4 to maintain the current passing therethrough, constant.However, as contacts AR/4 are open at this time the voltage output of the transformer regulator for Zone l remains constant, the current passing through the material in this Zone 1 varying with the temperature, i.e. resistance, of the material. At the end of the 4 minutes 55 seconds period of time, the time switch 9 open deenergising auxiliary relay 10 and opening contacts AR/1, AR/2, AR/3, AR/5, AR/6 and AR/7, whilst closing contacts AR/4. Thus the contactors C for zones 2, 3 and 4 are opened isolating the transformer regulators 5 from the heating electrodes 2 in these zones, and the constant current controllers 6 are isolated from the transformer regulators for these zones, preventing any incorrect adjustment of the transformer regulators when the controllers 6 sense zero current flow.However, the contactor for Zone 1 remains closed and, with contacts AR/4 also closed, the transformer regulator and constant current controller for Zone 1 measure the current flowing through the material in Zone 1, this current being dependent upon the resistance and hence upon the temperature of this material. When the temperature of the material flowing through Zone 1 deviates from the desired value, its resistance varies correspondingly and hence the current will vary from its set-point. The controller then adjusts the voltage via the regulator to again achieve the desired current and hence to regain the desired temperature. This regulating action takes place within the 5 seconds the time switch 9 is open, the time switch then closing to once again maintain a constant voltage across Zone 1 whilst measuring and adjusting the current passing through Zones 2, 3 and 4. This process is continuously repeated whilst the forehearth is in use, tile temperature of the material in upstream Zone 1 being measured and a corrective adjustment being made during the 5 second period in each 5 minute repeat time. During this 5 second period no other currents pass through the material in the forehearth other than the current through Zone 1. Thus an accurate temperature measurement in Zone 1 is possible with no external external influences, an accurate adjustment being thus possible to attain the desired temperature in Zone 1. Having attained a desired temperature in Zone 1 minor corrections are only necessary in the downstream zones of the forehearth. Thus by virtue of the present invention a forehearth is provided which has a high degree of temperature control, based on accurate temperature measurement and adjustment, providing for optimum quality of the material, e.g. glass, flowing therealong. WHAT WE CLAIM IS:
1. An electric forehearth for conveying molten material from a furnace to a forming station, said forehearth comprising an elongate channel which is divided transversely into at least two zones for the sake of temperature control, at least one pair of heating electrodes projecting into the channel in each zone, the
electrodes of each zone being connected to a respective transformer regulator which is controllable by a constant current controller, each constant current controller being arranged to monitor the current flowing between the heating electrodes in a zone and to adjust the particular transformer regulator connected thereto, to seek to maintain a predetermined current value, a control circuit being adapted to disconnect the constant current controller, which monitors the heating current in one of said zones, from the transformer regulator for that zone, for a predetermined period of time, whilst allowing the or each other constant current controller to monitor and control the current in the or each other zone, and to reconnect the constant current controller to the transformer regulator for said one zone for a subsequent shorter predetermined period of time, whilst disconnecting the transformer regulator and constant current controller for the or each other zone from the heating electrodes in the or each other zone, for said shorter predetermined time.
2. A forehearth as claimed in claim 1, in which the forehearth is divided into four zones for the purposes of temperature measurement.
3. A forehearth as claimed in claim 1 or claim 2, in which a number of pairs of heating electrodes project into each zone.
4. A forehearth as claimed in any one of claims 1 to 3, in which the said one zone is the zone which is at the upstream end of the forehearth when in use.
5. A forehearth as claimed in any one of the preceding claims, in which said predetermined period of time is four minutes fifty five seconds and said shorter predetermined period of time is five seconds.
6. A forehearth as claimed in any one of the preceding claims, in which the control circuit includes an impulse timer, a time switch and a relay for controlling the constant current controllers and transformer regulators of each zone.
7. A method of controlling an electric forehearth, the forehearth comprising an elongate channel which is divided transversely into at least two zones for the sake of temperature control, at least one pair of heating electrodes projecting into the channel in each zone and being connectible to a transformer regulator and constant current controller in a control circuit, said method comprising the steps of maintaining, for a predetermined period of time, a constant voltage across electrodes in one zone whilst both constantly monitoring the electric current passing between electrodes in the or each other zone and adjusting the voltage thereacross to maintain a substantially constant current therebetween, and, for a subsequent shorter predetermined period of time, monitoring the current passing between the electrodes of said one zone and adjusting the transformer regulator to achieve a predetermined current value through this zone, the electrodes of the or each other zone being disconnected from current and voltage sources for this subsequent shorter predetermined period of time, these steps being sequentially and continuously repeated as desired.
8. An electric forehearth for conveying molten material from a furnace to a forming station, constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
9. A method of controlling an electric forehearth, substantially as hereinbefore described with reference to the accompanying drawings.
GB2272578A 1978-05-25 1978-05-25 Fore-hearth control system Expired GB1603687A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2272578A GB1603687A (en) 1978-05-25 1978-05-25 Fore-hearth control system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2272578A GB1603687A (en) 1978-05-25 1978-05-25 Fore-hearth control system

Publications (1)

Publication Number Publication Date
GB1603687A true GB1603687A (en) 1981-11-25

Family

ID=10184111

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2272578A Expired GB1603687A (en) 1978-05-25 1978-05-25 Fore-hearth control system

Country Status (1)

Country Link
GB (1) GB1603687A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018009768A1 (en) * 2016-07-07 2018-01-11 Watlow Electric Manufacturing Company Heater bundle for adaptive control and method of reducing current leakage
US10619888B2 (en) 2016-03-02 2020-04-14 Watlow Electric Manufacturing Company Heater bundle for adaptive control and method of reducing current leakage

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10619888B2 (en) 2016-03-02 2020-04-14 Watlow Electric Manufacturing Company Heater bundle for adaptive control and method of reducing current leakage
WO2018009768A1 (en) * 2016-07-07 2018-01-11 Watlow Electric Manufacturing Company Heater bundle for adaptive control and method of reducing current leakage
CN109479341A (en) * 2016-07-07 2019-03-15 沃特洛电气制造公司 The method of heater beam and reduction current leakage for self adaptive control
TWI664873B (en) * 2016-07-07 2019-07-01 美商瓦特洛威電子製造公司 Heater bundle for adaptive control and method of reducing current leakage
CN109479341B (en) * 2016-07-07 2022-05-27 沃特洛电气制造公司 Heater bundle for adaptive control and method for reducing current leakage

Similar Documents

Publication Publication Date Title
US3506429A (en) Apparatus for improving thickness uniformity in down drawn glass sheet
US3836689A (en) Electric glass furnace with zone temperature control
US4277274A (en) Process for controlling molten glass variables
US4780120A (en) Bushing balance controller and method of using same
YU308080A (en) Arrangement for regulating electrodes at electric arc furnaces
US3954433A (en) Method of and apparatus for coordinating the application of heat to a melt from sources above and below the melt surface
US4247733A (en) Electrically heated glass forehearth
US4323383A (en) Method and apparatus for uniformly heating a glass stream within the feeder of a glass melting furnace
US2376488A (en) Control apparatus
CA1237460A (en) Electrically heated forehearth and method of controlling molten glass temperature therein
GB1603687A (en) Fore-hearth control system
US2659182A (en) Size control of linear bodies
US4546485A (en) Method and apparatus for producing uniform strands from a split fiber glass bushing
SE419930B (en) PROCEDURE AND DEVICE FOR CONTROL OF THE ELECTRO-LAYER GRAPHICATION OF MELTABLE ELECTRODES IN AN EXTENDED COOKILL
GB1527082A (en) Monitoring for incipient electrode failure in joule effect heating
US4412334A (en) Method of melting vitreous materials and use of the suitable device for the accomplishment of the method
US2158136A (en) Electric power system
SU977411A1 (en) Electric glass melting furnace
US3080737A (en) Method and apparatus for heating glass preparatory to delivery
DE3031087C2 (en) Procedure for setting the temperature of an industrial furnace
DE710876C (en) Temperature control system with program control for several control points
US3097251A (en) Means for making fibres of vitreous material
SU743965A1 (en) Method of automatic control of regenerative glass smelting furnace
SU818032A1 (en) Ore-smelting furnace
SU447375A1 (en) The method of automatic temperature control in the preparation of glass to develop

Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee