1. Field of the Invention
This invention relates to rolling mills producing hot rolled rod and bar products, and is concerned in particular with an improved and more efficient method of operating the finishing sections of such mills.
2. Description of the Prior Art
In a conventional rolling mill finishing section, a typical example of which is described in U.S. Pat. No. 3,336,781 and diagrammatically depicted at 10 in
Feed products FP1 are received from an upstream intermediate mill section (not shown) and are rolled into finished products FP2 in all or some of the successive roll passes S1-S10.
In still another rolling sequence, the roll passes of roll stands S5 and S6 are additionally dummied, with appropriate changes to the work rolls of the roll passes of roll stands S1-S4 in order to roll the same sized feed product into a finished product having a diameter of 11.5 mm.
It will be seen, therefore, that by progressively dummying roll passes, three different finished products sizes (5.5 mm, 9.0 mm, and 11.5 mm) are rolled from a feed product having the same entry size (17.1 mm). This rolling of different sized finished products from the same sized feed product is commonly referred to as “single family” rolling.
However, a problem with this conventional rolling methodology is that only a relatively narrow range of finished product sizes can be produced from one entry size. Thus, as shown in
The primary objective of the present invention is to expand the range of sizes of finished products that can be rolled from the same sized feed product, thus advantageously reducing the number of differently sized feed products required to produce a given range of finished products.
A companion objective of the present invention is to broaden the range of finished product sizes that can be rolled from each feed product size.
In accordance with the present invention, a feed product is rolled into different sized finished products in a rolling mill finishing section which comprises a plurality of rolling units arranged along the mill pass line. Each rolling unit includes two roll stands with work rolls configured to define successive oval and round roll passes. The roll stands are designed to effect specific area reductions on products rolled through their respective oval and round roll passes.
Feed products having a given entry size are rolled through the roll passes of the roll stands of all of the rolling units in a first rolling sequence to produce finished products having a first reduced size. Feed products having the same entry size are rolled into finished products having different reduced sizes by providing altered rolling sequences in which a selected rolling unit is replaced along the pass line with rolling units having roll stands designed to effect area reductions that differ from those of the roll stands of the replaced rolling unit. Rolling units downstream from the replaced rolling unit are removed from the pass line. The roll stands of rolling units upstream from the replaced rolling unit remain unchanged.
These and other features and attendant advantages of the present invention will now be described in greater detail with reference to the accompanying drawings, wherein:
With reference initially to
In addition to the rolling units RU1-RU5, the modular finishing mill 12 includes rolling units RU5a and RU5b. The rolling units are shiftable onto and off of the pass line PL along tracks (not shown) in a conventional manner known to those skilled in the art, and as described for example in U.S. Pat. No. 5,595,083, the description of which is herein incorporated by reference.
In an altered rolling sequence, rolling unit RU5 is removed from the pass line and replaced by rolling unit RU5a. The roll stands S9 and S10 of rolling unit RU5a are designed to effect area reduction respectively of 25.0% and 21.0%, which differ from the area reductions of the roll stands S9, S10 of rolling unit RU5. In this altered rolling sequence, in which the roll stands of rolling units RU1-RU4 remain in place and unchanged, the same feed product FP1 is rolled into a finished product having a diameter of 5.25.
In a different altered rolling sequence, rolling unit RU5 is replaced by rolling unit RU5b having roll stands S9, S10 designed to effect area reductions respectively of 16.6% and 15.0%. With this rolling sequence, the same feed product FP1 is rolled into a finished product having a diameter of 6.0 mm.
In still other altered rolling sequences, rolling units RU4, RU3, RU2, and RU1 are progressively replaced by rolling units RU5, RU5a, and RU5b, with the roll stands of the rolling units downstream of the replaced rolling unit having been dummied.
By doing so, the same sized feed product FP1 can be rolled into fifteen different finished product sizes ranging in diameter from 5.25 mm to 14.0 mm.
The same methodology can be employed to roll a feed product FP1 having a diameter of 19.5 mm into fifteen other finished products ranging in diameter from 6.35 mm to 16.0 mm.
It thus will be seen that by employing the modular finishing mill 12 in accordance with the method of the present invention, and as compared to conventional rolling practices with a block type finishing mill 10, a wider range of differently sized finished products can be produced from a smaller number of differently sized feed products. This results in significantly less loss of production time when shifting from one entry size to another.
Number | Name | Date | Kind |
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3336781 | Wilson | Aug 1967 | A |
5595083 | Shore | Jan 1997 | A |
Number | Date | Country |
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1048367 | Nov 2000 | EP |
1110630 | Jun 2001 | EP |
1958710 | Aug 2008 | EP |
Number | Date | Country | |
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20110048093 A1 | Mar 2011 | US |