Metallurgical apparatus – Means treating solid metal
Patent
1981-04-23
1983-07-19
Stallard, W.
Metallurgical apparatus
Means treating solid metal
148 9R, C21D 900, B23K 700
Patent
active
043940072
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
In thermal deburring (also called thermochemical deburring), the pieces of work to be deburred are introduced into a deburring chamber. Combustion gas and oxygen are introduced into the deburring chamber via metering valves. The gas mixture is ignited in the chamber by an electric ignition device. When hydrogen is used as the combustion gas, the combustion produces water while releasing heat. The procedure runs its course within a few milliseconds. As a result of the heat being released, temperatures of approximately 3,000.degree. C. occur in the chamber. After the pieces of work have been deburred, the deburring chamber is opened and the pieces of work are replaced with new pieces of work which are to be deburred.
The thermal deburring process causes an intentional removal of the material of which the work piece to be deburred is made, particularly at the edges. However, it is disadvantageous that there is also an unintended removal of material at the surfaces or portions of the deburring chamber forming its inner wall, this unintended removal being locally quite variable in severity.
THE INVENTION
Briefly, in order to deal more effectively with the erosion of the chamber, the chamber walls are made easily interchangeable and are designed subject to considerable wear.
The deburring chamber according to the invention has the advantage over the prior art that tool costs in thermal deburring can be greatly reduced. Because parts of the deburring chamber which are subject to differing amounts of wear are embodied separately, relatively small units can be exchanged very easily and quickly. Since the deburring chambers operate with considerable cycling times (20 seconds, for instance), the deburring chamber walls are exposed to severe alternating thermal stresses, which can cause rupturing because of thermal shock and thus can cause a severe reduction in long-term rupture strength. The inner walls of the deburring chamber are subjected to a continuous alternating stress in synchronism with the cycle. The removal of material from deburring chamber parts can be of an order of magnitude of up to one millimeter per 50,000 deburring cycles.
In this area, the deburring chamber according to the invention is therefore made up of easily exchangeable units which are subjected to relatively high wear. Such units are, in particular, the interior walls of the deburring chamber.
A particularly advantageous deburring chamber design comprises an interior deburring chamber ring or sleeve with an upper portion or ceiling of the deburring chamber adapted thereto and an associated closing bottom plate. These three parts, adapted to one another, define the interior of the deburring chamber and represent those parts which are most subjected to wear.
The inner parts of the deburring chamber are embodied, in terms of their strength, in such a manner that they are independently capable of withstanding the stresses which occur during thermal deburring. To this end, a clearance fit is provided between the inner deburring chamber ring and the outer cooling ring, in order to limit the continuous alternating temperature stress and accordingly the reduced long-term rupture strength to the part subject to wear. This principle is also applied to the upper portion of the deburring chamber, which when cold has a slightly inwardly curved shape but under temperature stress has a locking fit with the adapter located above it. However, a further form of embodiment of the deburring chamber provides that the inner ring is fitted into the surrounding cooling ring or some additional ring in such a manner that the surrounding ring absorbs the forces, while the inner ring is selected with a view solely to the factor of wear.
DRAWING
One exemplary embodiment of the invention is shown in the drawing and described in detail, with further advantages being discussed, in the following description. The FIGURE is a schematic representation of a deburring chamber which does not include the associated machine frame.
DESCRIPTION OF THE PREF
REFERENCES:
patent: Re29408 (1977-09-01), Geen et al.
patent: 1186162 (1916-06-01), Bauer
patent: 3645521 (1972-02-01), Geen et al.
patent: 3901488 (1975-08-01), Riddle
patent: 4025062 (1977-05-01), Johnstone et al.
Robert & Bosch GmbH
Stallard W.
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