Metallurgical apparatus – Means for cutting solid metal with heat – e.g. – blowpipes – Means for removing surface material – e.g. – scarfing
Patent
1990-09-12
1991-12-10
Kastler, S.
Metallurgical apparatus
Means for cutting solid metal with heat, e.g., blowpipes
Means for removing surface material, e.g., scarfing
266100, B23K 500
Patent
active
050711059
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a gas torch with a device permitting visual observation of a molten pool produced by the torch, more particularly intended for use in scarfing torches, i.e for removing blemishes, cracks, tears, inclusions from the surface of steel billets, ingots and the like.
Intermediate products of the iron and steel industry such as slabs, blooms and billets of steel, for example, are generally converted into flat products by hot rolling, whether they were initially cast into ingots or continuously cast.
With saving energy and reducing production costs being a continuous preoccupation, iron and steel industry specialists seek to obtain the maximum benefit from the heat content of the cast intermediate product in carrying out the rolling operation.
However, the intermediate products may have near their surface visible and invisible defects such as cracks, tears, shuts or the like which may remain in the rolled product or even become accentuated and lead to their rejection, not to mention the possibility of damaging the surface of the rolling mill rolls.
For this reason it is necessary to examine the intermediate products before they are rolled to determine if they may be rolled directly or if they first require treatment to eliminate or repair defects or if their quality is so poor that they must be recycled.
Until now the methods and equipment used for this examination to detect defects has required the intermediate product to be cool beforehand; this was directly opposed to the preoccupation with saving energy.
It is known to observe a pool of molten metal produced by a gas torch using a video camera independent of the torch and disposed near the pool, for example to monitor the removal of tears from the surface of metal ingots before they are rolled.
When observing the pool the camera and the ancillary equipment may be splashed with molten metal from around the pool and are exposed to the heat of the torch flame and of the pool itself. The severe environment exposes the equipment (camera, etc) to significant risk of damage and makes it impossible to view the pool from close up. What is more, the smoke produced by melting the pool significantly degrades the quality of the image and this means that it is not possible to detect small tears or other defects.
There is known from the patent U.S. Pat. No. 4,450,339 an arc welding torch having an optical system providing an image of a welded area to enable adjustment of the position of an electrode and of the current fed to it. The torch described has various disadvantages. The optical system is protected by a quartz window far from the hot area which delimits the angle view of the optical system. This window may be damaged or soiled by spatter due to the electrical arc, the low flowrate of rare gas used to create a neutral atmosphere being insufficient to repel such spatter.
A main object of the invention is therefore the observation of a molten pool produced by a torch without any of the disadvantages mentioned above.
To this end, the invention consists in a gas torch having a body having at least one gas feed pipe provided at one end with a nozzle having a main orifice and a visual observation optical device comprising a lens coaxial with the main orifice of the nozzle and an optical fibre.
In accordance with the invention, the lens is disposed inside the feed pipe, leaving sufficient flow cross-section for the gas, which flows over it during operation of the torch, with the result that the surface area of the main orifice substantially matches that embraced by the angle of view of the lens and the optical fibre has an end part starting from the lens and extends in a gas-tight manner to the outside of the body towards a device for interpretation of light information.
The flow of gas over the optical device repels spatter from the molten pool and keeps the lens clean. It also cools the device and so enables the lens to be moved nearer the nozzle, increasing the angle of view and the area of the molten pool that is viewed.
According to one advantageo
REFERENCES:
patent: 4450339 (1984-05-01), Corby, Jr.
Patent Abstracts of Japan, vol. 9, No. 92 (M-373)(1815), 4-20-85, JP,A,59218294.
Donze Bertrand
Donze Michel
Kastler S.
Sollac
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