GB1572055A

GB1572055A - Igniting of thermic lances

Info

Publication number: GB1572055A
Application number: GB1463777A
Authority: GB
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 1976-04-23
Filing date: 1977-04-06
Publication date: 1980-07-23
Also published as: FR2348900B1; ATA279677A; DE2617903A1; FR2348900A1; AT350457B; CH604094A5; CA1063505A

Description

(54) IGNITING OF THERMIC LANCES (71) We. HILTI AKTIENGESELL SCHAFT, a Corporation organised and existing under the laws of the Principality of Liechtenstein, of Schaan. Liechtenstein, do herebv 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 particularlv described in and by the following statement:: This invention relates to a method of. and means for use in. igniting a thermic lance, for use in the cutting or boring or hard materials, such as concrete. rock and steel having an outer tube with a plurality of core wires present therein. oxygen being supplied between the wires and between the latter and the outer tube. in which the thermic lance is caused to ignite by bringing its front end into contact with or into the vicinity of burning material.

Oxvgen-burning thermic lances have been used for a long time for boring holes, as well as for demolition work, and in the course of time such thermic lances have been developed and improved. Since nowadays they are relativelv easilv controllable. thev are produced in smaller sizes for performing finer work. One such use is for example. the cutting of reinforcing bars or rods. when these are encountered during the drilling of dowel holes in reinforced concrete.

However. problems have been encountered in igniting these oxygen-burning thermic lances. In the past, ignition has been effected by heating the thermic lance to white heat at its front end. for example with the aid of a welding torch. thereby to ignite the same. As an alternative possibilitv. the front end of the thermic lince is brought into contact with or into the vicinity of glowing charcoal or smouldering wood whilst oxygen is being fed therethrough. However, these methods are complicated and timeconsuming. Particularly in relation to work in which a thermic lance has to be ignited relatively frequently. the known methods are not satisfactory.

The problem underlying the invention is to provide a method of, and means for, achieving rapid and simple ignition of an oxygen-burning thermic lance.

Pursuant hereto, the invention provides for the front end of the oxygen-burning thermic lance to be brought into contact with or into the vicinity of a burning body, independent of the lance and formed of magnesium particles, and is thereby ignited.

When magnesium burns. as is well known, considerable heat is developed. It thus takes only a very short time for the oxygen-burning thermic lance to reach the necessary temperature to ignite when using the method of the invention. Furthermore, the method of the invention has the advantage that smouldering or glowing materials do not have to be permanently present in the vicinity of the person using the thermic lance during the work. The risk of fire is, thus, considerably limited.

The body used for the ignition can take various forms. It is. for example. advantageous for the body formed of magnesium particles to be pressed from magnesium powder. Such a pressed powder body is very compact and. in addition. has the advantage that it is generally combustible only when oxygen is fed to its vicinity. If desired, auxiliary substances which influence the combustion of the body can be added to the body.

In an advintageous version the body formed of magnesium particles is pressed from magnesium chips. In this event. for instance waste magnesium chips. arising in the processing of materials consisting of magnesium or magnesium alloys. can be used directlv. The combustion rloperties of the body. consisting of magnesium chips.

can be influenced by pressing with a yleiltcr or lesser pressure.

For handling purposes it is particularly advantageous if the body formed of magne- sium particles is pressed into a tablet. Such a tablet has the advantages thnt it can be shaped so as to have no corners which crumble awav easilv and also so as to be simple to pack. For different sizes of ther- mic lances. the tablet can be produced in different sizes.

For facilitating ignition of the body formed of magnesium particles it is advin- tageous for an ignition aid. consisting of easilv-ignitable material to be added to the body. Such an ignition aid is particularly advantageous in the case of verv firmlv pressed magnesium bodies which will burn only when oxygen is fed thereto. since then the easily-ignitable ignition aid can be ignited first and only then does the supply of oxygen have to be ignited. The risk of accident is thereby considerably reduced.

As examples. a fuse tape (or fuse cord) of the type used in pyrotechnics. or a thin magnesium strip. can be used as the ignition aid. However. use could be made of wire wool threads.

In order to retain and concentrate the heat arising during ignition of the thermic lance and to minimise the effect of external influences. such as wind, which mav be disturbing when working in the open air. it is advantageous for the ignition of the thermic lance to be effected in a crucible.

Such a crucible provides. in addition. the advantage that it screens off from the user the very severe glaring effect arising from the burning magnesium. Moreover, the crucible guarantees that the ignition of the body formed of magnesium particles is alwavs effected on a fireproof substrate.

The invention will be described further.

by way of example. with reference to the accompanying drawing in which the single figure is a sectional elevation illustrating a preferred manner of carrving the method of the invention into effect. and preferred means therefor.

In the drawing. a thermic lance, desii- nated as a whole by the numeral 1. comprises an outer tube 2. and core wires 3 drnwn therein. Gaps 4 are present between the core wires 3 themselves. and between the wires 3 and the outer tube 2. and these enable oxygen to be supplied through the thermic lance 1.

Arranged ill all open-t)pped crucible : is a body 6 made of mignesitim particles. The body 6 has a wick 7 which serves as ignition aid.

'or igniting the thermic lance 1. the body 6 formed ol magnesium particles is inserted into the crucible 5 and is ignited with the aid of the wick 7. 'l'hen one introduces the front end 1(/ t)l the thermic lance I into the crucible 5 antl turns on the oxygen supply.

Because ol the presence of the oxygen. the body 6 begins to burn violently: the front end Ict of the lance I is accordingly heated bv the resulting rapid development of heat, tip to white heat, and finally itself begins to hurn. If. when the thermic lance has been ignited and withdrawn from the crucible 5.

the entire body 6 formed of magnesium particles has not been consumed. then hy simply covering of the open top of the crucible 5 the combustion of the body 6 can be brought to a halt. It may then be possible to use the body a second time for the ignition of the thermic lance 1.

WHAT WE CLAIM IS:- 1. A method of igniting a thermic lance.

for use in the cutting or boring of hard materials such as concrete. rock and stcel.

having an outer tube with a plurality of core wires present therein. oxygen being supplied between the wires and between the latter and the outer tube. and wherein the thermic lance is caused to ignite by bringing its front end into contact with or into the vicinitv of burning material. characterised in that the front end of the thermic lance is brought into contact with or into the vicinity of a burning body. independent of the lance and formed of magnesium particles, and is thereby ignited.

'. A method as claimed in claim 1.

characterised in that the body formed of magnesium particles is pressed from magnesium powder.

3. A method as claimed in claim 1.

characterised in that the body formed of magnesium particles comprises pressed magnesium chips.

A. A method as claimed in claim 1. 2 or 3. characterised in that the body formed of magnesium particles is pressed into a tahlet.

5. A method as claimed in any preceding claim characterised in that an ignition aid. consisting of easily-ignitable material. is added to the body formed of magnesium particles.

6. A method as claimed in anv preced ing claim characterised in that the ignition of the thermic lance is effected in a crucible.

7. A method of igniting a thermic lance substantially as hereinbefore described with reference to and as illustrated in the accompaning drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

In an advintageous version the body formed of magnesium particles is pressed from magnesium chips. In this event. for instance waste magnesium chips. arising in the processing of materials consisting of magnesium or magnesium alloys. can be used directlv. The combustion rloperties of the body. consisting of magnesium chips.

can be influenced by pressing with a yleiltcr or lesser pressure.

For handling purposes it is particularly advantageous if the body formed of magne- sium particles is pressed into a tablet. Such a tablet has the advantages thnt it can be shaped so as to have no corners which crumble awav easilv and also so as to be simple to pack. For different sizes of ther- mic lances. the tablet can be produced in different sizes.

For facilitating ignition of the body formed of magnesium particles it is advin- tageous for an ignition aid. consisting of easilv-ignitable material to be added to the body. Such an ignition aid is particularly advantageous in the case of verv firmlv pressed magnesium bodies which will burn only when oxygen is fed thereto. since then the easily-ignitable ignition aid can be ignited first and only then does the supply of oxygen have to be ignited. The risk of accident is thereby considerably reduced.

As examples. a fuse tape (or fuse cord) of the type used in pyrotechnics. or a thin magnesium strip. can be used as the ignition aid. However. use could be made of wire wool threads.

In order to retain and concentrate the heat arising during ignition of the thermic lance and to minimise the effect of external influences. such as wind, which mav be disturbing when working in the open air. it is advantageous for the ignition of the thermic lance to be effected in a crucible.

Such a crucible provides. in addition. the advantage that it screens off from the user the very severe glaring effect arising from the burning magnesium. Moreover, the crucible guarantees that the ignition of the body formed of magnesium particles is alwavs effected on a fireproof substrate.

The invention will be described further.

by way of example. with reference to the accompanying drawing in which the single figure is a sectional elevation illustrating a preferred manner of carrving the method of the invention into effect. and preferred means therefor.

In the drawing. a thermic lance, desii- nated as a whole by the numeral 1. comprises an outer tube 2. and core wires 3 drnwn therein. Gaps 4 are present between the core wires 3 themselves. and between the wires 3 and the outer tube 2. and these enable oxygen to be supplied through the thermic lance 1.

Arranged ill all open-t)pped crucible : is a body 6 made of mignesitim particles. The body 6 has a wick 7 which serves as ignition aid.

'or igniting the thermic lance 1. the body 6 formed ol magnesium particles is inserted into the crucible 5 and is ignited with the aid of the wick 7. 'l'hen one introduces the front end 1(/ t)l the thermic lance I into the crucible 5 antl turns on the oxygen supply.

Because ol the presence of the oxygen. the body 6 begins to burn violently: the front end Ict of the lance I is accordingly heated bv the resulting rapid development of heat, tip to white heat, and finally itself begins to hurn. If. when the thermic lance has been ignited and withdrawn from the crucible 5.

the entire body 6 formed of magnesium particles has not been consumed. then hy simply covering of the open top of the crucible 5 the combustion of the body 6 can be brought to a halt. It may then be possible to use the body a second time for the ignition of the thermic lance 1.

WHAT WE CLAIM IS:-

1. A method of igniting a thermic lance.

for use in the cutting or boring of hard materials such as concrete. rock and stcel.

having an outer tube with a plurality of core wires present therein. oxygen being supplied between the wires and between the latter and the outer tube. and wherein the thermic lance is caused to ignite by bringing its front end into contact with or into the vicinitv of burning material. characterised in that the front end of the thermic lance is brought into contact with or into the vicinity of a burning body. independent of the lance and formed of magnesium particles, and is thereby ignited.

'. A method as claimed in claim 1.

characterised in that the body formed of magnesium particles is pressed from magnesium powder.

3. A method as claimed in claim 1.

characterised in that the body formed of magnesium particles comprises pressed magnesium chips.

A. A method as claimed in claim 1. 2 or 3. characterised in that the body formed of magnesium particles is pressed into a tahlet.

5. A method as claimed in any preceding claim characterised in that an ignition aid. consisting of easily-ignitable material. is added to the body formed of magnesium particles.

6. A method as claimed in anv preced ing claim characterised in that the ignition of the thermic lance is effected in a crucible.

7. A method of igniting a thermic lance substantially as hereinbefore described with reference to and as illustrated in the accompaning drawings.