US3791697A

US3791697A - Method and apparatus for flame jet cutting

Info

Publication number: US3791697A
Application number: US00251183A
Authority: US
Inventors: Z Hokao; T Makajima
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-05-12
Filing date: 1972-05-08
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12
Also published as: GB1396996A

Abstract

A cutter proper is provided with a burner having at its tip a nozzle that injects a combustion flame of oxygen and kerosene at supersonic speed. Thermit material is supplied to the flame jet that is injected by burning the oxygen and kerosene at supersonic speed whereby the concrete or stone material and the like is burnt at such high temperatures where said material to be cut is melted. The cutting body can be cut by melting without relying on destruction of human work by injecting the flame jet toward the cutting body.

Description

United States Patent Hokao et a1.

METHOD AND APPARATUS FOR FLAME JET CUTTING Inventors: Zenjiro I-Iokao, Shimoyasumatu 50-80, Tokorozawa-chi, Saitama-ken', Taiitsu Makajima, Nakato 2482, Musashimurayama-chi, Tokyo, both of Japan Filed: May 8, 1972 Appl. No.: 251,183

Foreign Application Priority Data May 12, 1971 Japan 46/32111 Oct. 6, 1971 Japan t 46/79018 Jan. 28, 1972 Japan 47/10688 U.S. Cl. 299/14, 110/22 B, 175/13,

431/4, 431/114, 143/158 Int. Cl. E21c 21/00 Field of Search 299/14; 175/13, 14;,431/4,

[451 Feb. 12, 1974 [56] References Cited UNITED STATES PATENTS 3,116,798 l/1964 Job 175/14 2,794,620 6/1957 Arnold et a1 175/14 2,392,353 1/1946 Aitchison 175/13 2,470,999 5/1949 Meinckem, 110/22 B X 3,620,013 11/1971 Rogers et a1 431/114X Primary Examiner-Ernest R. Purser Att0rney, Agent, or Firm-Meyer, Tilberry & Body [57] ABSTRACT A cutter proper is provided with a burner having at its tip a nozzle that injects a combustion flame of oxygen and kerosene at supersonic speed. Thermit material is supplied to the flame jet that is injected by burning the oxygen and kerosene at supersonic speed whereby the concrete or stone material and the like is burnt at such high temperatures where said material to be cut is melted. The cutting body can be cut by melting without relying on destruction of human work by injecting the flame jet toward the cutting body.

7 Claims, 6 Drawing Figures PATENTEDFEBIZIQH 3 ,791,697

SHEET 2 [IF 2 FIG. 3

METHOD AND APPARATUS FOR FLAME JET CUTTING This application pertains to the art of cutting and more particularly to the cutting of stone-like materials.

The invention is particularly applicable to cutting concrete, stone material and other materials similar to the concrete by a flame jet and will be described with particular reference thereto; however, the invention has broader application as will be more fully appreciated by those skilled in the art.

Heretofore, concrete "and stone materials have been cut generally by means of chipping work by hand using hammer or chisel. This work comprised cutting the concrete with the chisel by gradually destroying it and the time and labor required for accomplishing the work was tremendous with the resultant work efficiency being quite low. Also, as the chipping work was being carried out, numerous cracks were caused in the stone by the action of striking the chisel. Because of this cracking, the remaining portion of the cut concrete which was to be used following cutting frequently could not be used due to severe cracks.

In cutting relatively thin concrete plates, mechanical machines such as motor saw and the like have heretofore been utilized. However, wear and tear of the component machine parts is excessively great and in the case where the machines must be used for extended time periods, valuable work time is required for replacement and maintenance of the machine components. Further, when cutting thick concrete blocks and the like, large cutting machines have been required which, in turn, increased the costs and operational difficulties thereof.

The present invention contemplates a new and improved method and apparatus which overcame all of the above referred problems and others and provides method and apparatus for flame jet cutting which is simple, economical and readily adaptable to use with different stone or concrete-like materials having various thicknesses.

In accordance with the present invention, there is provided a method of flame jet cutting particularly adapted for use in cutting stone or concrete-like materials. The method comprises the steps of providing a combustion flame jet comprised of oxygen and kerosene in a burner; ejecting the jet from the burner at a supersonic velocity; and, supplying a thermit to the jet following ejection from the burner whereby the material is cut by the simultaneous combustion of the oxygen, kerosene and thermit.

In accordance with a more limited aspect of the present invention, the method further includes the step of cooling the burner by injecting a cooling fluid onto the periphery of the flame jet.

In accordance with another aspect of the present invention, there is provided an apparatus particularly adapted for use in flame jet cutting of stone or concrete-like material. The apparatus includes a cutter head having a burner therein for permitting desired combustion of oxygen and kerosene therein to form a cutting flame jet; means for supplying selected amounts of the oxygen and kerosene to the burner; means for permitting escape of the jet from the burner at high velocity; and, means for continuously directing a cooling fluid at least around the outer periphery of the burner.

In accordance with another aspect of the present invention, the apparatus further includes means for directing a thermit material to the flame jet adjacent the burner and means for continuously supplying the thermit material to the directing means.

In accordance with still another aspect of the present invention, means are provided to permit a continuous cooling fluid flow onto the periphery of the flame jet at least from a position immediately adjacent the burner during escape of jet from the burner.

In accordance with yet another aspect of the present invention, the apparatus includes means for muffling the noise created by apparatus operation.

The principal object of the present invention is the provision of a method and apparatus for flame jet cutting stone or concrete-like material.

Another object of the present invention is the provision of a method and apparatus for flame jet cutting which is simple.

Another object of the present invention is the provision of a method and apparatus for flame cutting which is efficient in use.

Another object of the present invention is the provision of a method and apparatus for flame jet cutting which is readily adapted for use with stone or concretelike materials of different types and sizes.

Still another object of the present invention is the provision of a method and apparatus for flame jet cut ting which is inexpensive to employ.

Still another object of the present invention is the provision of a method and apparatus for flame jet cutting which provides improved cuts in stone or concretelike materials.

The invention may take form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof and wherein:

FIG. 1 is a flow sheet schematically showing a cutting device and a fuel supply circuit according to the present invention;

FIG. 2 is a vertical cross-sectional view of a tip portion of the burner;

FIG. 3 is a flow sheet schematically showing a cutting device and a fuel supply circuit according to the present invention in which the burner includes means for ejecting water from the burner tip so as to surround the jet flame;

FIG. 4 is a vertical cross-sectional view of the tip portion of the burner shown in FIG. 3;

FIG. 5 is an elevational view of the tip portion of the burner shown in FIG. 4; and,

FIG. 6 is a vertical cross-sectional view of a muffler mounted at a tip portion of the cutter head.

Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiment of the invention only and not for purposes of limiting same, there is shown in FIG. 1 a burner 2 provided at a tip of a cutter head 1. An oxygen cylinder 35 supplies oxygen under a pressure of generally between 40-45 psi to burner 2 and a kerosene cylinder 4 supplies kerosene under a pressure of generally between 40-45 psi to burner 2. A cylinder 5 of high pressure nitrogen is employed to cause the kerosene to flow from cylinder 4 to burner 2. With reference to FIG. 2, it will be seen that the tip portion of burner 2 is provided with a rubber nozzle 6 and a combustion chamher 7 which is communicated with the nozzle. At the end of combustion chamber 7 spaced remote from nozzle 6, there is provided an injector 9 threaded to a holder 8. A plurality of injecting outlets l bored on the central portion of injector 9 are communicated with a central opening 11 in holder 8 and opening 11 is communicated with a kerosene supply pipe 12 for injecting kerosene as will hereinafter become apparent. The plurality of injecting outlets 13 bored on external peripheral portion of injector 9 are communicated with an external peripheral opening 14 of the holder 8 with opening 14 being communicated with an oxygen supply pipe 15 which surrounds the external periphery of kerosene supply pipe 12. The injected kerosene is mixed with the oxygen through its atomization and is burned at high temperatures in the range of 3,500 to 8,800K in combustion chamber 7 by its ignition at the tip of the burner 2. As the mixture is ejected from nozzle 6, it is transformed to supersonic flame jet of Mach number -6. Simultaneously therewith, the external wall surface of combustion chamber 7 is heated to a high temperature so that it is necessary to effect continuous cooling thereof. In the preferred embodiment and for needed cooling, a sleeve 17 is provided between the external peripheries of nozzle 6, combustion chamber 7 and an outer tube 16. A through-hole 18 is provided in sleeve 17 adjacent its base end and the other end is disposed in a tight fitting contact with the external periphery of holder 8. Also, the opposite end of holder 8 is connected to an inner tube 19 which surrounds the external periphery of oxygen supply pipe 15. Cooling fluid, which comprises water in the preferred embodiment, is supplied under a pressure of approximately liters per minute at a pressure of 4 to 6 psi to the space or channel formed between oxygen supply pipe and inner tube 19. From there, it is introduced to the space or channel formed between combustion chamber 7 and sleeve 17 through an opening 20 in holder 8 to cool the external wall of the combustion chamber. It is then discharged to the outside by passing through hole 18 and thence through the space or channel formed between sleeve 17 and outer tube 16. In FIGS. 1 and 3 of the drawings, reference numeral 21 generally designates a tank for holding the cooling water and numeral 22 generally designates a pump for pumping the water to the cutter head.

A thermit powder supply pipe 23 is provided along the outside of cutter head 1 and includes a tip formed with jetting port 24 generally directed toward the tip direction of the burner 2. The thermit material or powder is conveniently stored in a thermit powder container 25 and is supplied under pressure to the end of burner 2 by pressurized air from a compressor 26 from where it is jetted outwardly of port 24 toward the flame jet. When the flame jet is directed against a body 27 which is to be cut, that is, concrete material or the like, the thermit is burned on the surface of the cut 28. The flame at that point becomes one of high temperature so that body 27 is effectively melted at out 28. The molten material is caused by the melting or cutting action and is removed from the area of the cut by the pressure, generally in the range of from l0l5 psi, of the flame jet itself. The material from the cut also acts to melt additional successive new surface of body 27 so that the area of the cut is rapidly melted. In practice, the cutting speed is about 6-8 meters per hour when reinforced concrete plate having a thickness of 10 cm is being cut.

Although the preferred embodiment of the invention employs thermit powder which is supplied by means of a pipe, it will be understood that the powder is not necessarily required and that a thermit rod may be intermittently inserted into the cutting surface of the concrete.

The concrete surface which has been cut in a manner as hereinabove described eliminates the cracks which have heretofore occurred in the case of the chiseling type of cutting work. Thus, the shape of the concrete surface when using the subject invention may be favorably maintained. Accordingly, regardless of the thickness and the size of the concrete material, cutting can be effected so that machining such as boring and the like, is made possible. Again, it will be appreciated that the subject invention may be utilized not only for the concrete but also for stones and other concrete-like materials.

Since, body 27 is heated to high temperatures at the periphery of that portion to be cut during the time of cutting, it is desirable to provide means for cooling that peripheral area. In the situation where the body to be cut is comprised of concrete, cooling is most advantageous as concrete has properties of showing brittleness to the heat which, of course, is not desired.

The device shown in FIGS. 3, 4 and 5 is designed to cut the body while providing cooling to an extent that the thermal influence can be ignored even if it is highly influenced by the heat.

In the device shown in FIG. 4, a flow passage 29 for the cooling fluid is formed on the external peripheries of combustion chamber 7 and oxygen supply pipe 15. The cooling fluid is fed under pressure from tank 21 by means of pump 22. The cooling fluid which has cooled the external wall of combustion chamber 7 is jetted outwardly from the tip of the cutter head through a plurality of jetting out ports 30 formed on the periphery of the opening portion of the tip of burner 2. By this arrangement, jetting cooling water surrounds the periphery of the flame jet to thereby impinge the cutting area to effect cooling and shields the sounds of the operation of the flame jet.

As described hereinabove, the cutting body is cooled by the cooling fluid at the periphery of the cutting area while it is being cut so that the cutting action does not cause thermal influence on a cutting body which has a tendency of thermal alteration. Thus, the shape of the cut area in the body may be maintained as desired. Since the cooling fluid is jetted outwardly from the tip of burner, a continuous circulation circuit for the fluid is not required in order that the device itself may be constructed in a light weight and compact form. Further advantages are that the use of a special heat resisting alloy is not required at the tip portion of burner 2 and that the noise caused by operation of the flame jet is shielded so as to provide sound insulation.

The apparatus shown in FIG. 6 shows means for muffling the sound of the flame jet. The jet cutter according of the present invention has an extremely great injection sound of the flame jet. Because of this, the noise level could cause problems with persons near the apparatus during its operation. This is particularly true when the apparatus is utilized in a residential area.

Therefore, and with reference to FIG. 6, a muffler 31 is provided which is comprised of an inner tube 32 and an outer tube 34 disposed concentrically therearound so that there is a clearance or channel 33 therebetween. Clearance 33 is sealed at both ends of inner tube 32 and outer tube 34. The inner tube is formed so as to include a plurality of bulged portions 35 along its periphery which, in turn, include a plurality of water jetting out holes 36 on the sides thereof. A cylindrical mounting portion 37 is formed on the base end of muffler 31 with a jet cutter 38 inserted thereinto and affixed thereto by means of any convenient retaining members 39 such as screws and the like. Also, a water feeding port 40 is formed on the muffler with a hose 42 leading from a pump 41 connected to port 40.

When jet cutter 38 is used, the ignition is carried out in the condition where the tip of the jet cutter is caused to protrude to the outside of muffler 31. After ignition and when the flame is stabilized, the muffler is caused to move forward so that the tip of jet cutter 38 is situated generally at the vicinity of mounting portion 37 and retained in that position by means of retaining members 39. In this condition, pump 41 is operated so that pressurized fluid or water is introduced into the clearance or channel 33 from water feeding port 40 such that the inside of clearance 33 is filled with the fluid. The fluid is then caused to jet outwardly from ports 36 of tube 32 to form a film of water on the periphery of the flame. The noise of operation of the jet flame is thereby shielded by the wall of water in clearance 33, the film of water in the periphery of the jet flame and the irregular surface formed by the bulged portions of the inner tube.

The invention has been described with reference to the preferred embodiment. Obviously, modification and alteration will occur to others upon the reading and understanding of this specification. It is my intention to include all such modification and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Having thus described our invention, we now claim:

1. A method of cutting a stone or concrete-like material comprising the steps of: providing a combustion jet flame comprised of oxygen and kerosene in a burner; ejecting said jet flame from said burner at supersonic velocity; supplying a thermit to said jet flame following ejection from said burner; ejecting a cooling fluid about the periphery of said jet flame; directing said jet flame and thermit against an area of the material to be cut, and directing said cooling fluid about the periphery of the area of the material to be cut.

2. An apparatus for flame cutting stone or concretelike material comprising: a jet flame cutter head adapted to provide continuous combustion of a mixture of oxygen and kerosene received therein to form a jet flame; means to supply metered amounts of oxygen and kerosene to said jet flame cutter head; means to ignite and sustain combustion of said oxygen and kerosene to provide a jet flame in said jet flame cutter head; means to eject said jet flame from said flame cutter head at supersonic velocity; means to provide a coolant about the periphery of said flame cutter head; means for supplying thermit to said jet flame; and means to direct said coolant about the periphery of said jet flame.

3. The apparatus defined in claim 2, including a thermit powder supply pipe with a nozzle positioned adjacent the tip of said flame cutter head; a thermit powder container; and thermit powder pressure feeding means connected to said container to supply thermit powder under pressure to said powder supply pipe nozzle.

4. The apparatus of claim 2, wherein said jet flame cutter head includes a combustion chamber having a nozzle at one end; injector means for injecting a mixture of oxygen and kerosene into said chamber, said injector means being disposed on the side of said chamber opposed to said nozzle; an oxygen supply pipe connected at one end to said injector means and at the opposite end to oxygen supply means; a kerosene supply pipe connected at one end to said injector means and at the opposite end to a kerosene supply means; a thermit powder supply pipe secured at one end to the tip of said jet flame cutter head and at the other and to a supply of thermit powder; and a liquid cooling tube encircling said jet flame cutter head connected to a supply of liquid coolant.

5. The apparatus of claim 4, including a plurality of liquid coolant outlet ports in the tip of said flame cutter head communicating with said liquid cooling tube and adapted to direct coolant about the periphery of said jet flame and about the periphery of impingement of said jet flame against said material to be cut.

6. The apparatus of claim 2, including a noise muffler comprising an elongated inner tube dimensioned to be slidably received co-axially over said jet flame cutter head, said inner tube including a plurality of axially spaced apart annular pockets projecting radially outwardly from said tube; an outer tube co-axially received over said inner tube and sealed to provide a closed fluid chamber there between, port means in said annular pockets to provide communication between said inner and outer tubes; and means to introduce a fluid coolant under pressure into said chamber to flow through said port means into said inner tube to muffle the sound of, and impinge the periphery of, said jet flame.

7. The apparatus defined in claim 6, including means to adjustably position said muffler longitudinally along said jet flame cutter head.

Claims

2. An apparatus for flame cutting stone or concrete-like material comprising: a jet flame cutter head adapted to provide continuous combustion of a mixture of oxygen and kerosene received therein to form a jet flame; means to supply metered amounts of oxygen and kerosene to said jet flame cutter head; means to ignite and sustain combustion of said oxygen and kerosene to provide a jet flame in said jet flame cutter head; means to eject said jet flame from said flame cutter head at supersonic velocity; means to provide a coolant about the periphery of said flame cutter head; means for supplying thermit to said jet flame; and means to direct said coolant about the periphery of said jet flame.