Gas Supply Device for Flame Scarfing

The invention relates to a gas supply device for flame scarfing of billets, ingots and slabs, which is provided with gas supply ducts, for example for heating oxygen, heating gas and flame scarfing oxygen to extend to the flame scarfing burners and a transverse bore extending through the burner is subdivided by means of bolts with annular grooves in which O-rings are located to form limited flame scarfing sections which do not extend beyond the maximum possible flame scarfing width.

In flame scarfing or oxygen gouging of billets, ingots and slabs, the workpiece edge is raised to ignition temperature with the heating flame of the flame scarfing burner which is provided with such gas supply devices. So-called "flame scarfing oxygen" is thereafter additionally blown through the the flame scarfing burner to burn the material that has been raised to ignition temperature and by virtue of its kinetic energy drives the resultant iron oxide slag before it is the flame scarfing apparatus or the flame scarfing machine or the workpiece move relative to each other.

The heating oxygen and heating gas, for example propane or natural gas, as well as flame scarfing oxygen are supplied to the flame scarfing burners or to the flame scarfing burner through pressure regulators, ducts, adjustable valves and hose ducts. Since more than one flame scarfing burner must often be supplied, the system is divided so that each burner on such a machine is independently supplied with gas and oxygen but can also be shut down by means of valves or solenoid valves. The so-called flame scarfing width of a flame scarfing machine can thus be adapted to the width of the workpiece that is being processed.

A shape for a flame scarfing burner has been developed which, although still comprising individual burners of the greatest possible width, acts in the manner of a large wide flame scarfing burner as regards the gas and oxygen flow, to act beyond the maximum flame scarfing width of the machine. This is an advantage over burners of the prior art since the use of a plurality of adjacently arranged self-contained burners often resulted in undesirable scores or grooves on the workpiece corresponding to the appropriate flame scarfing width of a burner. In some circumstances the individual burners are even now subdivided more finely into flame scarfing sections of the orders of magnitude of 25 mm to 100 mm and are switched on or shut down by means of valves or solenoid valves. However, there is now no space to construct a pipeline supply system which is designed for each individual segment. Instead, a compact valve is produced for switching on and shutting down the supply of oxygen and gas in sections.

The media flow via a manifold bridge through the device for switching on and shutting off, the so-called burner plates, each having a supply port for heating gas or heating oxygen for each segment. The entry port for each segment extends into a bore which extends transversely through the entire nozzle plate from which a large number of small heating ports extend to atmosphere. Since each individual feed in the plate corresponds to a section which can be switched on and shut down it is necessary for the transverse bore in the burner plate front to be correspondingly subdivided. This is achieved in conventional manner by providing a bolt with annular grooves, O-rings being fitted on the the bolts into the annular grooves which are spaced from each other at the distance of a flame scarfing section and the entire O-ring bolt assembly is then inserted into the transverse bore or transverse bores in the front part of the burner and fixed from the outside by screw-mounting.

This construction functions in principle but suffers from substantial disadvantages because installation and maintenance can be performed only with relative difficulty and requires a substantial expenditure in terms of time and cost: to begin with, the annular grooves on the bolt and the O-rings must be so dimensioned and fitted that the entire sealing assembly can be inserted into the transverse bore. It is therefore necessary to make concessions regarding the reliability of sealing and this in turn sometimes leads to leakages between the individual sections so that sections which are intended to provide a full burning performance do not burn well because of a gas loss while adjacent burning sections which are shut down continue to burn or cause gas loss. Secondly, it is possible for the O-rings to become squeezed, distorted or even forced from their seats when the sealing structure is inserted, more particularly if the external O-ring diameter in its prestressed state occupies a relatively large overall external diameter in the interests of providing proper sealing. This results in destruction of the seals and calls for dismantling and repair of the bolt construction and reassembly. This means that the work already required for the normal insertion of the seal structure becomes very time-consuming because it must be performed with great skill and care and, if the O-rings are damaged, which happens very frequently, the entire installation procedure must be repeated with the same expenditure in terms of time and the time required for any necessary dismantling procedure must also be added.

The situation becomes even more serious if an unsuccessful installation of the seal structure is detected only when the flame scarfing machine is set into operation. This will then also call for shutting down of the flame scarfing machine, dismantling of the imperfect burner plates and reassembling of the perfect burner plates, features which may lead to very substantial interference with the production flow and therefore to substantial production losses.

It is therefore the object of the invention to make available an improved gas supply device which avoids the disadvantages explained above the permits installation in a shorter length of time without difficulties, even by less skilled and trained expert personnel.

According to the invention, in a gas supply device of the kind described hereinbefore the bolt is constructed as a screwthreaded bolt with chamber sleeves slid thereupon the length of which corresponds approximately to the length of the desired flame scarfing sections and O-rings, loosely inserted prior to installation in adjustable annular grooves, are placed into an outwardly pressed state after insertion of the bolt system into the transverse bore by the tightening of nuts on the screwthreaded bolt end by reduction of the annular grooves.

In a further embodiment of the invention, the bolt comprises two screwthreaded bolts with screw heads and at least one chamber sleeve is provided with internal screwthreading and the remaining chamber sleeves with the O-rings are screw-mounted upon the screwthreaded bolts.

The invention will now be explained by reference to the annexed exemplified embodiments.

FIG. 1 shows a gas supply device with the novel bolt system in sectional form and

FIG. 2 is a modified embodiment of the bolt system.

As shown in FIG. 1, the chamber bolt which is inserted into the housing 1 of a burner plate, namely into the transverse bores 4 situated between the supply ports 2 and the exit ports 3, comprises a screwthreaded bolt 5 with chamber sleeves 6 slid thereover and having O-rings 7 inserted on the bolt 5 between the sleeves 6. A medium which is supplied from a supply port 2 can therefore pass only in the section defined by the O-rings 7 through the annular chamber formed by the transverse bore 4 and the core diameter of a chamber sleeve 6 to the exit ports 3.

The bolt 5 is inserted into the transverse bore 2 and aligned in a lightly prestressed state because the O-rings 7 are held in position only under light pressure without deformation. Further tightening of the nuts 10 on the screw-threaded bolt 5 causes the O-rings 7 to be compressed between enlarged portions 9 of the sleeves 6 so that they are expanded and thus bear sealingly and lockingly on the wall of the transverse bore.

As best seen in FIG. 2, a chamber sleeve 11 with internal screwthreading and two screws 12 can also be used in place of a screwthreaded bolt 5 with two nuts 10 to enable the chamber sleeve 11 to be clamped together at its installation site.