USRE26960E - Metal heating - Google Patents
Metal heating Download PDFInfo
- Publication number
- USRE26960E USRE26960E US26960DE USRE26960E US RE26960 E USRE26960 E US RE26960E US 26960D E US26960D E US 26960DE US RE26960 E USRE26960 E US RE26960E
- Authority
- US
- United States
- Prior art keywords
- air
- temperature
- metal
- heating
- furnace
- 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
Links
- 239000002184 metal Substances 0.000 title description 42
- 229910052751 metal Inorganic materials 0.000 title description 42
- 238000010438 heat treatment Methods 0.000 title description 34
- 238000002485 combustion reaction Methods 0.000 description 27
- 239000007789 gas Substances 0.000 description 23
- 239000000446 fuel Substances 0.000 description 17
- 238000000034 method Methods 0.000 description 12
- 239000000203 mixture Substances 0.000 description 11
- 229910000831 Steel Inorganic materials 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 239000002737 fuel gas Substances 0.000 description 7
- 230000007812 deficiency Effects 0.000 description 6
- 150000002739 metals Chemical class 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 230000001590 oxidative effect Effects 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 5
- 239000010949 copper Substances 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 238000005096 rolling process Methods 0.000 description 5
- 239000003345 natural gas Substances 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000007792 addition Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 210000001520 comb Anatomy 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
Definitions
- ABSTRACT OF THE DISCLOSURE A process of heating metals without scaling by heating with a stoichiometric mixture of fuel and combustion supporting gas until the metal reaches scaling temperature, then changing to a rich mixture and continuing the heating until the metal reaches the desired temperature.
- the present invention relates to the heating of metals and more partciularly to the scale-free heating of metals for hot forming or other purposes.
- the metal is heated in a furnace that is directly fired by burners using a substantially stoichiometric mixture of fuel gas and a combustion supporting gas containing oxygen which is usually air and will be so referred to herein [air] until the work reaches a temperature where its surface is about to oxidize.
- a combustion supporting gas containing oxygen which is usually air and will be so referred to herein [air]
- the fuel ratio is changed to a rich mixture so that the products of combustion are reducing or, in any event, non-oxidizing.
- the heating is continued under these conditions until the work is brought up to the desired temperature.
- the invention is applicable to the heating of any metal. It is particularly useful, however, in the heating of metals which oxidize at elevated temperatures such as steel or copper, for example.
- FIG. 1 is a section through a furnace of a type which can be used for the invention.
- FIG. 2 is a diagram showing the supplies of fuel and air and the controls for these supplies by which the invention can be carried out.
- FIG. 1 there is shown a furnace 1 in which a slab, billet or other metal piece 2 is to be heated to hot working temperature.
- the work piece is mounted on supports 3 so that the hot gases of the furnace can circulate around it in order to heat it evenly.
- the furnace is heated by a plurality of burners 4 which fire directly into the furnace chamber and around the work.
- burners are of a type shown in Pat. No. 3,262,484 and the disclosure thereof is incorporated herein by reference.
- the burners include a refractory block 5 that forms a portion of the furnace wall with each block being provided with a cup-shaped depression 6 in the face thereof into which fuel gas and combustion supporting gas, usually air, are discharged for burning.
- a chamber 7 Attachcd to the rear of the burners and to the furnace wall is a chamber 7 in which are located the supply pipes for fuel and air and through which furnace gases are drawn directly from the furnace chamber to preheat the air supply.
- the chamber is provided with a vent 8 through which these gases are exhausted.
- a main air supply 9 with several branches.
- One of these branches, 11, is connected to supply primary air to each of the burners of the furnace, two of which are shown in FIG. 2 of the drawing.
- Air flows from pipe 11 through branches 12 to the inlet pipe 13 of each burner.
- a secondary air line 14, also supplied by the main air supply 9, is connected with each of the burners through branches 15 that connect with secondary air pipe 16 of the burners.
- a third air supply line, called the ejector air and indicated at 17, is used to supply air to a pipe 19 in vent 8 to aspirate the furnace gases from the furnace chamber through burner chamber 7 to the atmosphere.
- a gas supply pipe 20 leading to all of the burners has a branch 21 to each burner, which branch is connected to a fuel supply pipe 22 of the individual burners.
- thermocouple 23 The temperature of the interior of the furnace is measured by a thermocouple 23, or other suitable temperature sensing device, which is connected by a lead 24 with a standard temperature controller 25.
- This controller and the other controllers, to be described below, are preferably of the pneumatic contol type and operate in a well known manner to vary a control air output proportionately with changes in temperature or other variables being measured.
- the control pressure from instrument 25 is applied through a control line 26 to a pneumatically operated valve 27 in the gas supply line.
- the temperature of the furnace is used to control the supply of fuel and the supply of fuel is used to control the amount of air.
- an orifice 28 in the fuel line downstream of control valve 27.
- the differential pressure across this orifice is applied to a standard ratio control instrument which may well be a controlling flow meter with an adjustable control point setting. Variations into the flow of the gas acting on this instrument produce a variable control pressure that is applied through a line 32 to a pneumatically operated valve 33 in the primary air supply line 11.
- a standard ratio control instrument which may well be a controlling flow meter with an adjustable control point setting. Variations into the flow of the gas acting on this instrument produce a variable control pressure that is applied through a line 32 to a pneumatically operated valve 33 in the primary air supply line 11.
- the air supply is also varied to maintain the proper ratio of fuel and air.
- the temperature of the work is used, as it increases, to vary the ratio of fuel to air that is supplied to the burners.
- the temperature of the work is measured by a thermocouple 34 or other suitable temperature responsive element which is connected by leads 35 to a pneumatic control instrument 36.
- control instrument 36 will produce a variable control pressure which is applied through control line 37 to a pneumatic control valve 38 located in secondary air supply line 14.
- a branch of line 37, indicated at 39, also permits this control pressure to be applied to the ratio adjusting mechanism of controller 31.
- the ejector air supply which is normally constant, can be regulated by a manually operated valve 41 that is located in the ejector air supply line 17.
- control instrument 31 is adjusted so that the proper ratio of fuel and air will be supplied to the burners.
- the burners are then ignited and the furnace is heated by radiation from the burner cups and the products of combustion.
- the furnace is maintained at the desired temperature, as measured by the temperature responsive element 23, by control instruments 25 and 31, adjusting valves 27 and 33 respectively.
- the work is to be heated for rolling or forging the furnace temperature will be about 2400 F. or higher.
- the combustion supporting gas-fuel gas [air-gas] ratio will be maintained at substantially stoichiometric, which for air and natural gas will be about 9.6 to l.
- the products of combustion for this fuel-air ratio are oxidizing to steel above about 1400 F.
- controller 36 will produce a control pressure in line 37, opening valve 38 and operating to adjust instrument 31 to change the air-gas ratio from stoichiometric to a rich mixture in which there is at least a 30% deficiency of air.
- the air-gas ratio will be about to 1.
- Valve 38 can be adjusted to open and instrument 31 can be adjusted to shift the gas-air ratio when the work reaches 1400 F. as mentioned, or the valve can be ad justed to open gradually and the instrument adjusted to shift ratio gradually as the work temperature varies through a range of temperature, say from 1300 F. to 1500 P. if desired. Adjustments of this type are conventional in pneumatic control instruments.
- the heating of the work will continue in the fuel-rich furnace atmosphere.
- This atmosphere is reducing and will not only prevent any oxidation of the work from taking place but will reduce any slight oxide that may have been formed while the metal continues to be heated to above a hot working temperature of 2250 to 2300 F.
- the work when the work is heated it has a clean surface and may be moved directly from the furnace to a rolling mill or forge, for example, without the delay ordinarily required for descaling and cleaning and loss of heat which occurs during that time.
- controller 36 is adjusted to apply a ratio adjusting pressure to ratio controller 31 and open valve 38 when the metal has reached a temperature of about 600 F. Thereafter the metal is heated in a non-oxidizing atmosphere as it is raised to a hot working temperature of about 1650 F.
- the method of heating a metal which oxidizes at elevated temperatures which comprises heating the metal in direct contact with products of combustion resulting from burning a substantially stoichiometric mixture of fuel gas and air in the presence of the metal until the metal has reached a temperature at which its surface will begin to oxidize in the presence of said products of combustion, then continuing the heating of the metal in direct contact with products of combustion resulting from burning, in the presence of the metal, a rich mixture of fuel gas and air having at least a 40% deficiency of air from said first mentioned temperature to the hot working temperature for said metal.
- the method of heating without scaling a material that oxidizes at elevated temperatures which comprises placing the material in the c pmbustion zone of a direct fired furnace having burners in the wall thereof, supplying fuel gas and air to the burners, regulating said supplies to substantially stoichiometric proportions, burning the fuel and air to heat the material to a temperature where surface oxidation will begin to take place, changing the fuel-air ratio to the burners so that there is at least a 40% deficiency of air, thereby creating a reducing atmosphere, and continuing to heat the material in said reducing atmosphere until the material has reached the final desired temperature.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US83585269A | 1969-04-29 | 1969-04-29 |
Publications (1)
Publication Number | Publication Date |
---|---|
USRE26960E true USRE26960E (en) | 1970-10-06 |
Family
ID=25270624
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US26960D Expired USRE26960E (en) | 1969-04-29 | 1969-04-29 | Metal heating |
Country Status (1)
Country | Link |
---|---|
US (1) | USRE26960E (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4511124A (en) | 1983-05-03 | 1985-04-16 | Lone Star Steel Company | Method and composition for fluidization of accumulated pit scrap in soaking pits |
-
1969
- 1969-04-29 US US26960D patent/USRE26960E/en not_active Expired
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4511124A (en) | 1983-05-03 | 1985-04-16 | Lone Star Steel Company | Method and composition for fluidization of accumulated pit scrap in soaking pits |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: FIRST PENNSYLVANIA BANK N A 19TH FL.CENTRE SQ WEST Free format text: SECURITY INTEREST;ASSIGNOR:SELAS CORPORATION OF AMERICA A CORP OF PA;REEL/FRAME:003997/0981 Effective date: 19820217 |
|
AS | Assignment |
Owner name: SELAS CORPORATION OF AMERICA A CORP. OF PA Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:FIRST PENNSYLVANIA BANK N.V., FOR ITSELF AND AS AGENT FOR THE PHILADELPHIA NATIONAL BANK;REEL/FRAME:004096/0520 Effective date: 19821231 |
|
AS | Assignment |
Owner name: BANCBOSTON FINANCIAL COMPANY,MASSACHUSETTS Free format text: SECURITY INTEREST;ASSIGNOR:SELAS CORPORATION OF AMERICA;REEL/FRAME:004557/0143 Effective date: 19860529 Owner name: BANCBOSTON FINANCIAL COMPANY, 100 FEDERAL STREET, Free format text: SECURITY INTEREST;ASSIGNOR:SELAS CORPORATION OF AMERICA;REEL/FRAME:004557/0143 Effective date: 19860529 |
|
AS | Assignment |
Owner name: SELAS CORPORATION OF AMERICA, PENNSYLVANIA Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:BANCBOSTON FINANACIAL COMPANY A MA TRUST;REEL/FRAME:004945/0988 Effective date: 19880805 Owner name: SELAS CORPORATION OF AMERICA, DRESHER, PA 19025 A Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:BANCBOSTON FINANACIAL COMPANY A MA TRUST;REEL/FRAME:004945/0988 Effective date: 19880805 |