Modular rolling mill

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, with each gear unit in turn being mechanically coupled to a driven line shaft by first bevel gear sets. The ratios of the first bevel gear sets progressively increase from the first to the last of the gear units to thereby accommodate a 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 level gear set of the penultimate gear unit. The line shaft is selectively coupled to the last gear unit via one or the other of its first and second bevel gear sets.

BACKGROUND DISCUSSION

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.

SUMMARY OF THE INVENTION

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:

DETAILED DESCRIPTION

With reference toFIG. 1, a modular rolling mill in accordance with the present invention comprises a plurality of separate rolling units10a,10b, and10carranged along a mill pass line “P.” The direction of rolling is indicated by arrow12. Each rolling unit has at least two pairs of work rolls14,16configured respectively to define oval and round roll passes. The rolls of each successive pair are staggered by 90° to effect twist-free rolling of long products, e.g., bars, rods, and the like.

With reference additionally toFIGS. 2 and 3, it will be seen that the work rolls are mounted on roll shafts18, and that intermediate drive trains are contained within the rolling units to mechanically couple the roll shafts to input shafts20. The input shafts are parallel and project to a first side “A” of the pass line. The intermediate drive trains include gears22on the roll shafts meshing with intermeshed gears24on shafts26, with one of the shafts26connected by a bevel gear set28to a shaft30. The shafts30carry gears32meshing with a gear34on the input shaft20.

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 rolls14,16with separate input shafts20.

A line shaft36extends 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 motor38located at the entry end of the mill.

The line shaft is subdivided into segments interconnected by clutches40. Each line shaft segment is coupled to an output shaft42by a first bevel gear set44contained in a gear unit46a,46b, and46cassociated with a respective rolling unit.

A coupling48connects each output shaft42to a respective input shaft20. The couplings are separable to accommodate removal of the rolling units to the second opposite side “B” of the pass line. A network of tracks50on side B is arranged to receive and convey rolling units removed from the pass line.

The ratios of the first bevel gear sets44are progressively increased from the first to the last of the gear units (viewed from right to left inFIG. 1). This accommodates the progressively increasing speed of the product being rolled along the pass line P.

The first bevel gear sets of gear units46aand46bare permanently coupled to the line shaft36. However, in the last gear unit46c, as can best be seen by further reference toFIG. 4, the drive gear44aof the first bevel gear set is journalled by means of a bushing52for rotation on the line shaft36. A second bevel gear set54is also contained in the last gear unit46c. The ratio of the second bevel gear set54is identical to the ratio of the first bevel gear set44of the penultimate gear unit46b, and its drive gear54ais also journalled for rotation relative to the line shaft36by means of a bushing.

The drive gears44aand54aare internally splined as at58. A clutch sleeve60is axially shiftable on the line shaft36by means of a clutch arm62or the like. The clutch sleeve is internally splined for mechanical interengagement with a splined segment64of the line shaft, and is externally splined for selective engagement with the internal splines58of one or the other of the drive gears44a,54a. When shifted to the position shown inFIG. 4, the clutch sleeve60mechanically couples the first drive gear44aand hence first bevel gear set44with the line shaft, thus driving the last rolling unit10cat the speed required to handle products emerging from the penultimate rolling unit10b.

As shown inFIG. 5, in an alternative operational mode, the penultimate rolling unit10bis shifted off of the pass line P onto the tracks50, and is replaced by a cooling unit66, which typically will comprise a series of water boxes or the like. In concert with this change, the clutch sleeve60will be shifted to the right (as viewed inFIG. 4), thus mechanically disengaging the first drive gear44afrom the line shaft36while simultaneously coupling the second drive gear54ato the line shaft.

The last rolling unit10cwill thus be driven at the same speed as the now sidelined penultimate rolling unit10b,which is the correct speed for thermomechanically rolling the cooled product previously rolled in the first rolling unit10a.

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 shaft36to the last gear unit via its first or second bevel gear sets44,54. 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.