Roll or roller – Rotatable relative to supporting shaft
Patent
1996-04-16
1998-03-10
Cuda, Irene
Roll or roller
Rotatable relative to supporting shaft
165 89, F28D 1102
Patent
active
057254664
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a peripherally drilled roll for the heat treatment of web material of the kind as described in the preamble of claim 1.
In such heating rolls having relatively high heating capacity an externally heated heat-carrying fluid is guided through the roll in axially parallel drilled passages disposed "peripherally" just beneath the surface of the roll.
During the flowing through of the roll the heat carrier gives off part of its thermal energy to the roll so that its temperature reduces. Accordingly, it is avoided in general that the heat carrier flows through the roll in one direction only, since the then resulting drop in temperature translates to the roll causing it to assume a temperature profile sinking from the inflow end to the outflow end. For this reason groups of neighboring drilled passages are interconnected so that the temperature profile is harmonized by temperature compensation actions between the partial flows of the heat carrier flowing through these drilled passages.
In integrated-type heated rolls of chilled cast iron, i.e. having journal pins forming a single component with the actual roll body, the neighboring drilled passages need to be each connected so that at the ends of the roll body additional slanting connecting drilled passages are incorporated to form the desired connection. The same function is satisfied by pockets milled in the roll body or in cap rings which close off the peripheral drilled passages at both ends.
For space reasons in this solution only a three-way design, also called TRIPASS, is possible. In this arrangement the heat-carrying fluid, after entering through the central bore of the pin, gains access to the central bore of the roll body from which it flows through a drilled passage slanting outwardly into the first of each group of three peripheral drilled passages in which it flows to the opposite end of the roll. At the other end of the roll it is directed through one or two intersecting connecting drilled passages in the roll body into the neighboring peripheral drilled passage in which it flows back to the outlet end. Here the redirection of the flow is repeated and the heat-carrying fluid enters the third peripheral drilled passage in which it is returned to the opposite end where it is directed back through a drilled passage guiding slanting inwardly to the central bore of the roll body. In conclusion the heat-carrying fluid leaves the roll either through the central bore of the pin at this end or it is directed back to the outlet end through the central bore of the roll body where it leaves the roll through the central bore of the outlet pin via a so-called double sealing head.
For rolls subject to high thermal and mechanical stress this integral design has shown itself to be inadequate for various reasons. The strength of the roll material alloyed to achieve the necessary hard-wearing properties is relatively low. In the integral design the pin is naturally of the same material, thus resulting in the mechanical load capacity of the roll being strongly restricted.
In addition, the connecting drilled passages in the roll body are sources of trouble. If two drilled passages intersect at an acute angle, then a sharp edge automatically results at the point of intersection which is washed on both sides by heat-carrying fluid. When changes in temperature occur in the heat-carrying fluid this point assumes the temperature thereof very quickly, whereas the remaining areas of the roll adapt to these changes only slowly. This results in thermal stresses which in the past have resulted repeatedly in internal cracks and, finally, in fracture of the roll as a whole.
The afore-mentioned disadvantages resulted in constructing rolls as highly loaded rolls having bolted pins of forged steel and the connecting passages relocated in the pins. One problem involved in this design is that in the pin and, where necessary, also at the ends of the actual roll body there is hardly enough room for accommodating the connecting passages and the holes neces
REFERENCES:
patent: 3120867 (1964-02-01), Nash
patent: 4964202 (1990-10-01), Pav et al.
patent: 5054543 (1991-10-01), Thomas et al.
patent: 5655596 (1997-08-01), Zaoralek
Eppli Bernd
Vomhoff Erich
Zaoralek Heinz-Michael
Cuda Irene
Schwabische Huttenwerke GmbH
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