Patent Application
20080196469
1. Field of the Invention
This invention relates generally to rolling mills producing long products such as rods and bars, and is concerned in particular with the provision of an improved modular mill.
2. Description of the Prior Art
Examples of known modular mills are disclosed in U.S. Pat. Nos. 5,595,083 and 6,053,022. These mills employ multiple motors driving gear boxes detachably coupled to successive rolling units. The rolling units each include roll stands with oval and round roll passes, and are interchangeable and rapidly shiftable onto and off of the mill pass line to thereby accommodate the single family rolling of progressively larger product sizes, as well as thermomechanical rolling at reduced temperatures. Although mechanically sound and advantageously flexible, as compared to block type mills, such modular arrangements are relatively complex and expensive, both to purchase and subsequently to maintain.
As disclose in U.S. patent application Ser. No. 11/403,671, it is also known to provide a modular rolling mill having successively arranged rolling units which are detachably coupled to gear units driven by a line shaft powered by a single motor. This arrangement also efficiently accommodates the single family rolling of progressively larger products and is less complicated and expensive than modular mills driven by multiple motors. However, it is not readily adaptable to thermomechanical rolling, which requires the introduction of relatively drastic cooling between selected rolling units.
The objective of the present invention is to provide an improved modular mill that is readily adaptable both to the single family rolling of progressively larger products, and to the introduction of interstand cooling when subjecting products to thermomechanical rolling.
In accordance with the present invention, a modular rolling mill comprises a plurality of rolling units having work rolls configured and arranged to progressively reduce the cross sectional area of a product received along a mill pass line. Gear units are mechanically coupled to each rolling unit. Each gear unit is in turn mechanically coupled to a driven line shaft by first bevel gear sets. The ratios of the first bevel gear sets are progressively increased from the first to the last of the gear units to thereby accommodate the progressively increasing speed of the product being rolled.
A second bevel gear set is associated with the last gear unit. The ratio of the second bevel gear set is the same as the ratio of the first bevel gear set of the immediately preceding (penultimate) gear unit. A clutch mechanism is provided for selectively coupling one or the other of the first and second bevel gear sets of the last gear unit to the line shaft.
In one operational mode, when all rolling units are in service, the first bevel gear set of the last gear unit is engaged. In a second operational mode, the penultimate rolling unit is removed and replaced by a cooling assembly which cools the product in advance of the last rolling unit, and the second bevel gear set of the last gear unit is engaged, allowing the last rolling unit to thermomechanically roll the thus cooled product at the speed of and in place of the removed penultimate rolling unit.
These and other features and advantages of the present invention will now be described in further detail with reference to the accompanying drawings, wherein:
With reference to
With reference additionally to
Although not shown, it will be understood that as an alternative to this arrangement, the intermediate drive trains could be configured to drive each pair of work rolls 14, 16 with separate input shafts 20.
A line shaft 36 extends along the first side A in parallel relationship to the pass line P. The line shaft is directly coupled to and driven by a drive motor 38 located at the entry end of the mill.
The line shaft is subdivided into segments interconnected by clutches 40. Each line shaft segment is coupled to an output shaft 42 by a first bevel gear set 44 contained in a gear unit 46a, 46b, and 46c associated with a respective rolling unit.
A coupling 48 connects each output shaft 42 to a respective input shaft 20. The couplings are separable to accommodate removal of the rolling units to the second opposite side “B” of the pass line. A network of tracks 50 on side B is arranged to receive and convey rolling units removed from the pass line.
The ratios of the first bevel gear sets 44 are progressively increased from the first to the last of the gear units (viewed from right to left in
The first bevel gear sets of gear units 46a and 46b are permanently coupled to the drive shaft 36. However, in the last gear unit 46c, as can best be seen by further reference to
The drive gears 44a and 54a are internally splined as at 58. A clutch sleeve 60 is axially shiftable on the line shaft 36 by means of a clutch arm 62 or the like. The clutch sleeve is internally splined for mechanical interengagement with a splined segment 64 of the line shaft, and is externally splined for selective engagement with the internal splines 58 of one or the other of the drive gears 44a, 54a. When shifted to the position shown in
As shown in
The last rolling unit 10c will thus be driven at the same speed as the now sidelined penultimate rolling unit 10b, which is the correct speed for thermomechanically rolling the cooled product previously rolled in the first rolling unit 10a.
In light of the foregoing, it will be appreciated by those skilled in the art that other equivalent mechanisms may be employed to selectively couple the line shaft 36 to the last gear unit via its first or second bevel gear sets 44, 54. A non-limiting example of one such equivalent mechanism might entail arranging one bevel gear of each gear set on a splined shaft segment, with means for axially shifting that gear into and out of engagement with its mating bevel gear.
