US3647570A - Oxygen trap scarfing method and apparatus - Google Patents
Oxygen trap scarfing method and apparatus Download PDFInfo
- Publication number
- US3647570A US3647570A US836233A US3647570DA US3647570A US 3647570 A US3647570 A US 3647570A US 836233 A US836233 A US 836233A US 3647570D A US3647570D A US 3647570DA US 3647570 A US3647570 A US 3647570A
- Authority
- US
- United States
- Prior art keywords
- oxygen
- scarfing
- preheat
- streams
- fuel gas
- 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 - Lifetime
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K7/00—Cutting, scarfing, or desurfacing by applying flames
- B23K7/06—Machines, apparatus, or equipment specially designed for scarfing or desurfacing
Definitions
- OXYGEN TRAP SCARFING METHOD AND APPARATUS Filed June 25, 1969 IO 20 3O INVENTOR PREHEAT TIME SECS THOMAS J'LYTLE ATTORNEY United States Patent 3,647,570 OXYGEN TRAP SCARFIN G METHOD AND APPARATUS Thomas James Lytle, West Orange, N..l., assignor to Union Carbide Corporation, New York, NY. Filed June 25, 1969, Ser. No. 836,233 Int. Cl. B23k 7/00 US. Cl. 148-9.5 4 Claims ABSTRACT OF THE DTSCLOSURE form a wedge shaped pocket to confine the burning preheating gases. This results in faster puddle formation and causes the puddle to be formed at a location just ahead of the projected converging point of the fuel and oxygen gas streams, rather than in back of the converging point where it would be formed by prior art methods.
- This invention relates to the thermochemical conditioning of ferrous metal bodies, commonly referred to as scarfing; and more particularly to method and apparatus capable of decreasing the time required for a complete scarfing cycle with post-mixed, fuel-oxygen preheat gas scarfing units by decreasing the time required for preheating the metal workpiece to be scarfed.
- the present invention is applicable to scarfing of hot as well as cold metal workpieces.
- a scarfing reaction is caused to take place by first raising the temperature of the metal surface to be scarfed to the ignition temperature of the metal in an oxygen atmosphere. This temperature, which may be lower than the melting point of the metal in air, is referred to as the reaction temperature. When the reaction temperature is reached, a puddle of molten metal is formed. The metal is removedthat is, the thermochemical scarfing reaction is caused to take placeby impinging a stream of oxygen on the puddle. In other words, in order to initiate a scarfing reaction a puddle must be formed before the scarfing oxygen stream can be turned on for the thermochemical scarfing reaction to begin.
- a complete scarfing cycle consists of four steps. First, the workpiece is positioned in register with the scarfing machine. Second, the scarfing units are closed, either automatically or manually, around all the sides of the workpiece which are to be scarfed. Third, preheating of the workpiece is caused to take pace by means of fueloxygen preheat flames so that a puddle of molten metal is formed; and fourth, the scarfing reaction is carried out by initiating the flow of scarfing oxygen. For example, when scarfing a 30 foot slab at 2000 F., positioning takes about 3 seconds, closing about 5 seconds, preheating about seconds, and scarfing the length of the slab about seconds. Thus, the total scarfing cycle for the 30 foot slab requires approximately 38 seconds.
- the time required for a complete scarfing cycle results in a scarfing rate or speed that is in some cases slower than the rate at which steel is rolled in a conventional mill. It is therefore desirable to decrease the time required to complete a scarfing cycle in order that the scarfing operation keep up with the production of the mill.
- Reduction in scarfing time may obviously be accomplished by reducing the time required for any of the above mentioned four steps which take place during a complete scarfing cycle. Since positioning and closing require a total of only about 8 seconds, the amount of improvement possible in these two steps is relatively small. Consequenty, the logical steps to shorten in order to improve the speed of a scarfing cycle are the preheating and/or scarfing steps.
- preheating time fails to improve. For example, if more fuel gas than conventionally used is provided, it tends to pinch off the supply of oxygen to the workpiece with a consequent decrease in heating capacity, thereby slowing down the preheating reaction.
- increasing the preheating oxygen splits apart the composite eifect of the upper and lower preheating fuel gas flames, and decreases the heating potential of the upper preheat flames by placing an intervening layer of cold oxygen between the upper preheat flames and the workpiece. Additionally, the increased oxygen acts as a cooling medium which draws heat from the workpiece.
- FIG. 1 is a side elevation of a scarfing unit according to the present invention which is provided with a row of trap oxygen orifice ports located in the upper preheat block above the row of preheat fuel gas ports.
- FIG. 2 is a front elevation of the scarfing unit shown in FIG. 1.
- FIG. 3 is a graph comparing the preheat times obtained by the use of the trap oxygen stream in accordance with the present invention as compared to a scarfing unit without such trap oxygen streams.
- thermochemically scarfing a metal body by directing a sheet-like stream of oxidizing gas at a reaction zone extending across the surface of said metal body at an acute angle of impingement to said surface, and by directing a plurality of parallel fuel gas streams so as to converge with at least the upper side of said sheetlike stream of oxidizing gas, wherein the improvement comprises: shortening the preheating time by directing a plurality of parallel streams of oxygen from above (relative to the surface of said metal body) said fuel gas streams at an acute angle to the surface of said metal body and so as to converge with the streams of oxygen and fuel gas, whereby the plane formed by said plurality of oxygen streams forms with the surface of said metal body a wedge shaped pocket to confine the preheating fuel gas and oxygen, thereby resulting in faster puddle formation and causing said puddle to be formed at
- the second aspect of the present invention comprises a continuous slot, post-mixed scarfing unit wherein said slot is formed between an upper preheat block and a lower preheat block which are in spaced relation to one another, wherein means are provided for discharging a sheet-like stream of oxygen through said slot for reacting with a metal surface to be scarfed as well as for burning preheat fuel gas, said scarfing unit being provided With a row of ports communicating with supply passages for discharging a plurality of parallel streams of preheat fuel gas from at least the upper preheat block, wherein the improvement comprises: a row of ports in said upper preheat block communicating with supply passages and located above said row of fuel gas ports for discharging a plurality of parallel streams of oxygen gas, said oxygen ports being directed at an acute angle to the metal surface to be scarfed so as to cause the oxygen streams emanating therefrom to form a wedge shaped pocket between the plane formed by said plurality of oxygen streams and the surface of said metal body to confine the fuel and oxygen gases discharged from their respective
- the oxygen curtain or plane above the preheat fuel gas streams formed by the trap oxygen streams causes a wedge shaped pocket to be formed between itself and the'surface of the metal being scarfed.
- the oxygen curtain is formed by a parallel row of oxygen ports 23 located above the row of upper preheat block fuel gas ports 15.
- High velocity fuel gas from both upper and lower preheat blocks 1 and 2 is directed into the pocket, becoming trapped in the pocket and consequently forced to mix intimately with the oxygen 9 emanating from the continuous slot 8. This permits considerable improvement to be made in preheat time by increasing the flows of fuel and oxygen that can be adequately mixed for combustion while precisely fixing the location of the puddle at the point where it is desired.
- the oxygen curtain provides a two-fold effect; first, it acts as a physical barrier to contain or trap the fuel and oxygen preheat gases causing them to burn in place; and second it permits an increase in the total amount of oxygen, thereby causing a hotter flame to be produced.
- the combination of these two effects improves heat transfer to the workpiece and concentrates the heat at a particular spot.
- the scarfing unit is comprised of an upper preheat block 1, a lower preheat block 2, a head 3 and a shoe 4 which rides on skids 5.
- the lower surface 6 of upper preheat block 1 and the upper surface 7 of lower preheat block 2 forms a continuous slot passage 8 for the oxygen stream 9.
- the rear end 10 of oxygen passage 8 communicates with a supply of oxygen (not shown).
- passage 8 is used to provide oxygen for combustion of the upper and lower preheat fuel gas streams 11 and 12. After the puddle 13 has been formed, the oxygen flow in stream 9 is increased to provide sufficient oxygen for the scarfing reaction.
- Upper preheat block 1 is provided with a plurality of preheat fuel gas passages 14 which terminate at the front face of the preheat block 1 in a row of fuel gas ports 15.
- Gas passages 14 communicate with a fuel gas header 24 located in head 3 from which they receive their supply of fuel gas.
- Natural gas is the preferred fuel gas; however, other fuel gases may also be employed such as, for example, methane, propane or coke oven gas.
- Lower preheat block 2 contains a plurality of fuel gas passages 17 which communicate with and receive a supply of fuel gas from header 18 located in head 3. Passages 17 terminate at the front face of the lower preheat block 2 in a row of lower preheat fuel gas ports 19.
- Both the upper preheat fuel gas ports 15 and the lower preheat fuel gas ports 19 are directed so that the straight line projections of the gas streams 11 and 12 emanating therefrom will converge with the straight line projection of the sheet-like stream of oxygen 9 at the converging point A on the surface of the metal workpiece W. Due to the aerodynamic effect of the hot gas streams as previously explained, the puddle 20 is formed upon the surface of the workpiece W at point B by prior art methods, i.e. without the use of the trap oxygen stream 21.
- the oxygen stream 9 is simply increased to the flow rate required for scarfing, and the workpiece W is then set in motion toward the right as indicated by the direction of the arrow, without the need for backing up the workpiece or scarfing unit. This would have been necessary had the puddle been formed at point B, in order that the scarfing reaction might begin by having the scarfing oxygen stream 9 impinge upon the puddle.
- the trap oxygen flow may be kept on, shut off completely, or lowered just to bleed slightly in order to prevent ports 23 from becoming plugged by the splatter of molten metal and slag. Keeping the trap oxygen on at full flow rates during the scarfing step has not been found to produce any beneficial results.
- FIG. 3 is a graph comparing preheating time using a post-mixed fuel-oxygen scarfing unit of the prior art with a unit in accordance with the present invention containing a row of trap oxygen ports above the upper preheat fuel gas ports to provide the oxygen curtain of the present invention.
- the flow rates of preheat fuel gas (natural gas) were approximately 3500 c.f.h. in both cases.
- the total amount of oxygen was likewise the same in both cases, i.e. about 7500 c.f.h.
- the distribution of the oxygen was different.
- the significance of the faster preheat time obtained in accordance with this invention is that it improves the preheating time at 2000 F., for example, by about 7 seconds, thereby cutting the scarfing cycle described preously from 38 seconds to about 30 seconds. This is an improvement of over in the scarfing cycle and is sufficient to enable the scarfing machine to keep up with a higher production rate than was formerly possible. It should be noted that the present invention provides a saving in preheating time by elimination of the need for backing up the workpiece or scarfing unit prior to initiation of the scarfing oxygen reaction, in addition to the shortening of the preheating time shown in FIG. 3.
- thermochemically scarfing a metal body by directing: (1) a sheet-like stream of oxidizing gas at a reaction zone extending across the surface of said metal body at an acute angle of impingement to said surface, and (2) a plurality of parallel fuel gas streams so as to converge with at least the upper side of said sheet-like stream of oxidizing gas, the improvement comprising: shortening the preheated time by directing a plurality of parallel streams consisting essentially of oxygen, 'which form a sheet-like oxygen gas curtain, from above said fuel gas streams at an acute angle to the surface of said metal body so as to converge with said streams of oxidizing gas and fuel gas at the converging point of the straight line projections of said oxidizing gas and fuel gas streams, whereby said oxygen gas curtain and the surface of said metal body form a Wedge-shaped pocket to confine the preheating fuel gas and oxidizing gas, thereby resulting in faster puddle formation and causing said puddle to be formed at a location ahead of the converging
- a continuous slot, post-mixed fuel-oxygen scarfing apparatus wherein said slot is formed between an upper preheat block and a lower preheat block which are in spaced relation to one another, wherein means are provided for discharging a sheet-like stream of oxidizing gas through said slot for reacting with a metal surface to be scarfed as Well as for burning preheat fuel gas, said scarfing apparatus being provided With a row of ports communicating with supply passages for discharging a plurality of parallel streams of preheat fuel gas from at least the upper preheat block to converge with said stream of oxidizing gas, the improvement comprising: a row of oxygen ports located in said upper preheat block above said row of fuel gas ports, communicating with supply passages, and capable of discharging a plurality of parallel streams of oxygen gas which form a sheet-like oxygen gas curtain, said oxygen ports being directed at the converging point of the straight line projections of the oxidizing gas and fuel gas streams so as to cause the oxygen curtain stream emanating therefrom to form a
Abstract
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US83623369A | 1969-06-25 | 1969-06-25 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3647570A true US3647570A (en) | 1972-03-07 |
Family
ID=25271495
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US836233A Expired - Lifetime US3647570A (en) | 1969-06-25 | 1969-06-25 | Oxygen trap scarfing method and apparatus |
Country Status (18)
Country | Link |
---|---|
US (1) | US3647570A (en) |
AT (1) | AT295967B (en) |
BE (1) | BE748249A (en) |
BG (1) | BG22066A3 (en) |
CA (1) | CA954022A (en) |
DE (1) | DE2018044C3 (en) |
ES (1) | ES381098A1 (en) |
FR (1) | FR2051280A5 (en) |
GB (1) | GB1290759A (en) |
LU (1) | LU61190A1 (en) |
NL (1) | NL145786B (en) |
NO (1) | NO126118B (en) |
RO (1) | RO58464A (en) |
SE (1) | SE371950B (en) |
SU (1) | SU496709A3 (en) |
TR (1) | TR16576A (en) |
YU (2) | YU159370A (en) |
ZA (1) | ZA704327B (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3850704A (en) * | 1972-02-15 | 1974-11-26 | Hilti Ag | Scarfing |
US3966504A (en) * | 1973-05-21 | 1976-06-29 | Centro-Maskin I Goteborg Ab | Method and apparatus for thermochemical gas scarfing |
FR2400985A1 (en) * | 1977-08-26 | 1979-03-23 | Union Carbide Corp | THERMOCHEMICAL SCREENING PROCESS AND APPARATUS |
US5304256A (en) * | 1991-12-09 | 1994-04-19 | Esab Welding Products, Inc. | Scarfing method |
US5358221A (en) * | 1991-12-09 | 1994-10-25 | The Esab Group, Inc. | Block assembly for use in metal scarfing apparatus |
CN112207404A (en) * | 2020-09-09 | 2021-01-12 | 浙江德宝通讯科技股份有限公司 | Wet-type dust removal cutting platform |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA1079181A (en) * | 1977-09-26 | 1980-06-10 | Union Carbide Corporation | Method and apparatus for producing a post-mixed, stabilized scarfing preheating flame |
ES8102873A1 (en) * | 1979-03-28 | 1981-02-16 | Union Carbide Corp | Method and apparatus for instantaneous scarfing of a workpiece surface |
GB2120772B (en) * | 1982-05-18 | 1985-09-18 | Exxon Research Engineering Co | Fuel burner device |
-
1969
- 1969-06-24 YU YU01593/70A patent/YU159370A/en unknown
- 1969-06-25 US US836233A patent/US3647570A/en not_active Expired - Lifetime
-
1970
- 1970-03-31 BE BE748249D patent/BE748249A/en not_active IP Right Cessation
- 1970-04-15 DE DE2018044A patent/DE2018044C3/en not_active Expired
- 1970-06-23 CA CA086,222A patent/CA954022A/en not_active Expired
- 1970-06-24 FR FR7023457A patent/FR2051280A5/fr not_active Expired
- 1970-06-24 GB GB1290759D patent/GB1290759A/en not_active Expired
- 1970-06-24 AT AT568470A patent/AT295967B/en not_active IP Right Cessation
- 1970-06-24 NL NL707009288A patent/NL145786B/en unknown
- 1970-06-24 NO NO2467/70A patent/NO126118B/no unknown
- 1970-06-24 ES ES381098A patent/ES381098A1/en not_active Expired
- 1970-06-24 TR TR16576A patent/TR16576A/en unknown
- 1970-06-24 SE SE7008746A patent/SE371950B/xx unknown
- 1970-06-24 LU LU61190D patent/LU61190A1/xx unknown
- 1970-06-24 YU YU1593/70A patent/YU33650B/en unknown
- 1970-06-24 ZA ZA704327A patent/ZA704327B/en unknown
- 1970-06-24 BG BG15011A patent/BG22066A3/xx unknown
- 1970-06-24 SU SU1454404A patent/SU496709A3/en active
- 1970-06-25 RO RO63742A patent/RO58464A/ro unknown
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3850704A (en) * | 1972-02-15 | 1974-11-26 | Hilti Ag | Scarfing |
US3966504A (en) * | 1973-05-21 | 1976-06-29 | Centro-Maskin I Goteborg Ab | Method and apparatus for thermochemical gas scarfing |
FR2400985A1 (en) * | 1977-08-26 | 1979-03-23 | Union Carbide Corp | THERMOCHEMICAL SCREENING PROCESS AND APPARATUS |
US5304256A (en) * | 1991-12-09 | 1994-04-19 | Esab Welding Products, Inc. | Scarfing method |
US5333841A (en) * | 1991-12-09 | 1994-08-02 | The Esab Group, Inc. | Nozzle insert for use in metal scarfing apparatus |
US5358221A (en) * | 1991-12-09 | 1994-10-25 | The Esab Group, Inc. | Block assembly for use in metal scarfing apparatus |
US5472175A (en) * | 1991-12-09 | 1995-12-05 | The Esab Group, Inc. | Block assembly for use in metal scarfing apparatus |
CN112207404A (en) * | 2020-09-09 | 2021-01-12 | 浙江德宝通讯科技股份有限公司 | Wet-type dust removal cutting platform |
Also Published As
Publication number | Publication date |
---|---|
NO126118B (en) | 1972-12-27 |
ZA704327B (en) | 1971-03-31 |
SE371950B (en) | 1974-12-09 |
RO58464A (en) | 1975-09-15 |
DE2018044B2 (en) | 1973-06-14 |
TR16576A (en) | 1973-01-01 |
DE2018044A1 (en) | 1971-01-07 |
LU61190A1 (en) | 1971-07-06 |
YU33650B (en) | 1977-12-31 |
GB1290759A (en) | 1972-09-27 |
AT295967B (en) | 1972-01-25 |
CA954022A (en) | 1974-09-03 |
NL7009288A (en) | 1970-12-29 |
DE2018044C3 (en) | 1974-01-03 |
NL145786B (en) | 1975-05-15 |
BG22066A3 (en) | 1976-11-25 |
YU159370A (en) | 1977-06-30 |
FR2051280A5 (en) | 1971-04-02 |
ES381098A1 (en) | 1973-07-01 |
BE748249A (en) | 1970-09-30 |
SU496709A3 (en) | 1975-12-25 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: L-TEC COMPANY, NEW YORK Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNION CARBIDE CORPORATION;REEL/FRAME:004436/0460 Effective date: 19850712 Owner name: L-TEC COMPANY, 666 THIRD AVENUE, NEW YORK, NY 100 Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNION CARBIDE CORPORATION;REEL/FRAME:004436/0460 Effective date: 19850712 |
|
AS | Assignment |
Owner name: SECURITY PACIFIC BUSINESS CREDIT INC., A DE CORP. Free format text: SECURITY INTEREST;ASSIGNOR:L-TEC COMPANY A NY LIMITED PARTNERSHIP;REEL/FRAME:004445/0860 Effective date: 19850716 |
|
AS | Assignment |
Owner name: L-TEC COMPANY, SOUTH CAROLINA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNION CARBIDE CORPORATION, A CORP OF NY.;REEL/FRAME:004610/0384 Effective date: 19860828 Owner name: L-TEC COMPANY, EBENEEZER ROAD, POST OFFICE BOX F-6 Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNION CARBIDE CORPORATION, A CORP OF NY.;REEL/FRAME:004610/0384 Effective date: 19860828 |