MXPA98000789A - Process and device for polishing with fire vid - Google Patents

Abstract

A method for polishing with glass fire using a gas-oxygen fuel flame is proposed, the method is characterized in that the fuel gas contains between 10 and 50% by volume of acetylene. The combustion gas can be formed by normal mixing, of combustion gas essentially free of acetylene, with acetylene. The device for carrying out the method of the invention has a burner, in which the gases pass through a mixer before reaching the nozzles, the mixer being connected to separate feeds of fuel gas and acetylene.

Description

PROCESS AND DEVICE FOR POLISHING WITH FIRE GLASS DESCRIPTION OF THE INVENTION To burnish glass articles with fire, these are, while still hot, superficially exposed to a gas flame, through which a thin layer of surface softens and therefore softens. For this purpose, flames of fuel gas / oxygen are used, which are generated by externally mixing burners, the fuel gas used being mainly natural gas, ethane, propane, butane, branching gas or the like, which contain only a proportion negligible acetylene or nothing [(AG PINCUS ET AL.: "Secondary Manufacturing in Glass Industry ", published in 1978 by" Books for Industry and the Glass Industry "Section III, Chapter 22, pages 87-88).] Acetylene is usually not used to burnish with glass fire, as its flame damages The glass, depending on the setting, may be too hot or contains a proportion of free carbon that penetrates the surface of the glass and discolours it, using only a relatively rare acetylene / oxygen mixture (US, A, 1,626,739), but the use of other combustible gases is also mentioned therein, however, a mixture of another fuel gas with acetylene is not mentioned.Mixes of another fuel gas with acetylene are known (GB, A, 215 739) but do not burn with fire , but rather for completely different applications, such as metallization guns, welding torches and the like, where in emphasis is apparently in principal form on metals. The fuel gas and acetylene are mixed before entering the burner (GB, A, 630 221). However, the relationship between acetylene and the other fuel gas is not mentioned. Although the quote also reveals the treatment of hard glass, does not mention polishing with fire. According to the invention, it has been found that the result of polishing with fire, in particular in the case of articles having a deeply structured surface, can be improved by using a combustible gas consisting of a relatively low part of acetylene, the which is mixed with the rest of the fuel gas. The proportion of acetylene is between 10 and 50%, preferably between 10 and 30% and most preferably between 10 and 25%. The proportion of acetylene results in a luminous flame, where the carbon, released during the decomposition of acetylene, emits intense heat radiation which, in addition to convection, improves the heat transfer to the surface to be treated, particularly also in the depths of the surface structure. Surprisingly, it has found that the proportion of carbon in the flame does not lead to a disadvantageous effect on the glass surface. This could be related to the fact that acetylene is diluted by the remaining fuel gas, free of bonds The carbon particles are burned more rapidly than in the case of a pure acetylene flame or a highly enriched acetylene flame, where the carbon particles tend to coagulate to a greater extent. form soot.

The fuel gas according to the invention is conveniently produced in a burner or immediately upstream of the burner as a fuel gas mixture essentially free of acetylene, for example, as has hitherto been used for polishing with fire and acetylene. If the mixture is produced only at the point of use, a burner arrangement according to the invention conveniently has, in addition to the connection for conventional fuel gas and for oxygen a connection for feeding acetylene, the fuel gas connection and the connection of acetylene leading to a mixing device, which feeds the burner orifice or the burner orifices. When an external mixing burner is used, as is usually used for polishing with fire, the result is a very hot flame of more than 2000 ° C. This can be operated very well sub and supers tequiómetricamente. The intensity of the radiant fraction of the heat transfer can be varied, varying the proportion of acetylene, this being easier to determine the most adequate mixing ratio, experimentally, depending on the application. The invention is explained below in more detail with reference to the drawing, which shows a diagrammatic illustration of an advantageous embodiment of an arrangement for polishing with fire. The burner 1, which can be of the conventional external mixing design, is fed with Oxygen through a line 2 having a manual control valve and a pressure reducer 4. The burner 1 also has a fuel gas connection 5, which is connected through a safety device without return 6 to a mixing device 7. The latter is fed, on the one hand with natural gas through a line 8, which contains a manual control valve 9 and a pressure reducer 10. On the other hand, it is fed with acetylene through a Line 11, which contains a safety device without return 12, a flow indicator 13, a manual control valve 14 and a pressure reducer 15. In the case shown, the mixing device 7 is designed as a venturi mixer.

However, it is also possible to use other mixing devices, which allow a sufficiently uniform mixing of acetylene with the remaining fuel gas. In a given example, good results are obtained in a process where 5 m3 / h of natural gas is fed at 0.5 bar of calibration, as a mixture with 0.5 to 1.5 m3 / h of acetylene, likewise to 0.5 bar of calibration, towards the burner.

Claims (3)

$ CLAIMS

1. A process for polishing with glass fire through a combusible gas / oxygen sheet, the fuel gas containing a substantial proportion of acetylene, characterized in that the proportion of acetylene in the fuel gas is between 10 and 50% in volume.

2. The process according to claim 1, characterized in that the fuel gas is formed as a mixture of a fuel gas substantially free of acetylene, with acetylene.

3. The process according to claim 1 or 2, characterized in that the proportion of acetylene is between 10 and 30% in volume. twenty