Metal deforming – By use of roller or roller-like tool-element – Included in roller-cluster
Reexamination Certificate
1999-10-07
2001-04-03
Butler, Rodney A. (Department: 3725)
Metal deforming
By use of roller or roller-like tool-element
Included in roller-cluster
Reexamination Certificate
active
06209376
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal manufacturing, and more particularly, to a metal rolling mill.
2. Description of the Related Art
Many earlier inventions that relate to the four-roll metal rolling mill design can be found in the following US Patents:
U.S. Pat. No. 2,019,081, titled Universal Roll Mill, by Heinrich Koppel in 1932
U.S. Pat. Nos. 2,041,271 and 2,071,712, titled Roll Stand Unit for a Continuous Reducing Mill, by Heinrich Stutting in 1934
U.S. Pat. No. 2,094,920, titled Rolling Mill, by Heber C. Inslee in 1937
U.S. Pat. No. 2,495,387, titled Mill, by Richard E. Rummins in 1950
All of the inventions above implemented a metal rolling mechanism that was based on four rolls and therefore shared many common characteristics. Most notable of which was that although their respective novel approaches to a four-roll-based design were theoretically and mechanically sound, however, the entailed press systems became extremely complex and bulky. The large number of bevel and other types of gears that are necessarily used in such systems reduce gearing transmission efficiency and subsequently usability of the inventions. This major disadvantage most likely accounts for the reason of why these inventions never saw practical use in the metallurgical industry.
A more interesting and modern instance of prior inventions that was also based on a four-roll mill design can be found in U.S. Pat. No. 5,144,827, titled Rolling Mill Stand, by Itsushi Iio in 1992. This invention far surpassed its predecessors in the 30's and 50's in terms of design and usability. In this invention, a single shaft is used to drive four coplanar shafts that are at right angle with respect to one another. Three pairs of bevel gears on the shafts transmit torque in between the driven shafts at 90° and cause the helical gears and the rolls on the shafts to rotate synchronously. The four driven shafts were made eccentric so that they could rotate off-center to achieve the effect of adjusting parting in between the rolls. After careful analysis of the patent, it was found that the overall design of structure in this invention was relatively novel but not without its shortcoming. The implementation of a single shaft driving two pairs of shafts via three pairs of bevel gears and four pairs of helical gears to attain synchronous rotations of the shafts and rolls resulted in low transmission efficiency and lower structural integrity of the rolling components. Bearings of other types and higher strengths could not be used to remedy the weakness in the components due to structural limitations, which inevitably rendered the overall rolling system incapable of sustaining higher rolling torque. The lack of public knowledge of this invention in the industry today can most likely be traced to these major disadvantages. This present invention aims to eliminate the shortcomings and disadvantages found in various prior inventions as described above and further improve upon the technical merits associated with the four-roll-based design. It is hoped that through this invention, the theoretically superior four-roll technology can finally be flawlessly implemented.
SUMMARY OF THE INVENTION
According to an embodiment of the present invention, the metal rolling mill comprises: a case body; a synchronously rotating four-roll system; and a synchronously adjustable four-roll press device. All components of the mill are contained within the covers of the case body and all are capable of rotation with respect to their own axes. Positioned parallel to the four edges of the case body are the four passive shafts that form the core components of the four roll systems inside the mill casing. A roll is mounted on each of the passive shafts such that its radius is perpendicular to the axis of rotation of the respective shafts. All rolls converge at the center of the mill and form a groove out of the joined contours of their heights. This groove serves as the passage for the steel rolling stock that is to be fed through the mill on a production line and pressed by the four rolls.
In addition to the shaft and the roll, the four roll system comprises an adjustment system which includes two eccentric bearing sleeves encircling the shaft on opposing sides of the roll, ball bearings, at least one spiral bevel gear, at least one adjustment ring, and at least one ring nut. The shaft with the roll is enveloped by two sets of bearing sleeves, one on each side of the roll. Ball bearings disposed under the sleeve contact the shaft. At least one adjustment ring slides along the shaft in between the bearing sleeves. The end of a first shaft not connected to the drive shaft includes a profile-shifted spiral bevel gear. A ring nut installed on the end of the shaft retains the profile-shifted spiral bevel gear in place. The profile-shifted spiral bevel gear on the end of the first passive shaft meshes with another profile-shifted spiral bevel gear on one end of a second shaft perpendicularly positioned with respect to the first shaft. As torque is delivered to the first passive shaft by single or double drive shafts, it is transmitted by the end mounted profile-shifted spiral bevel gears to the profile-shifted spiral bevel gear of the next adjacent shaft (e.g., the second passive shaft). In this manner, torque is propagated at right angles in between all of the passive shafts, and synchronous rotation of all rolls is achieved.
According to a preferred embodiment of the present invention, the external power train that supplies torque to the rolling mill comprises an external DC or AC motor-based electrical power source that generates torque, a coupler connecting such a power source to a gearbox, and a universal joint linking the gearbox to the single or double drive shafts of the rolling mill. Torque is first transmitted from the power source into the gearbox over the coupler, and then from the gearbox to the drive shaft of the rolling mill via the universal joint. The manner of torque transmission within the rolling mill after torque has reached the drive shaft(s) has been described in detail in the previous paragraph.
According to a preferred embodiment of the present invention, the adjustable roll device enables the four-roll rolling mill to have an adjustable roll groove. The adjustable roll device is implemented through a system of eccentric bearing sleeves disposed around the passive shafts on both sides of the roll. Worm drives are perpendicularly disposed through the casing body such that they engage profile-shifted worm gears installed in the mill casing. Two profile-shifted worm gears are positioned so as to tangentially influence the eccentric bearing sleeves from its two adjacent passive shafts. The worm drives are all tipped with sprocket wheels, which are linked together via a chain. Thus, as one of the worm drives is rotated either by hand or a remotely controlled servo device, the chain enables synchronous rotations of all worm drives, which in turn drives the profile-shifted worm gears causing the respective bearing sleeves to rotate synchronously. The eccentric design of the bearing sleeves results in a common deviation of the sleeves' bore centers from their geometric centers resulting in the simultaneous displacement of the axes of rotation of the passive shafts contained within the sleeves by a certain distance away from their original centerlines. This effect creates movement of the rolls in their respective radial planes away from the groove center, thus enabling the controlled adjustment of the groove.
During off-line maintenance, the mill is first taken off the production line and the rolls are removed from the case body. The rolls are then usually sanded down to a smaller diameter to remove the wear and tear on their perimeters. The allowable amount of change in diameter of a roll on a four-roll metal rolling mill falls within a range of 8 to 12 mm or greater depending on production requirements. This means that the mill can be re-deployed with smaller reworked
Butler Rodney A.
Incisive Technologies, Inc.
Keusey & Tutunjian, P. C.
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