Metal deforming – By use of roller or roller-like tool-element – With carrier for roller-couple or tool-couple
Reexamination Certificate
2001-08-22
2003-12-16
Tolan, Ed (Department: 3725)
Metal deforming
By use of roller or roller-like tool-element
With carrier for roller-couple or tool-couple
C072S205000, C072S366200
Reexamination Certificate
active
06662616
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to a method for flexibly rolling a metal band, wherein the metal band is rolled by guiding it through a roll gap formed between a first working roll and a second working roll, and wherein the size of the roll gap is varied in such a way that band sections having a greater band thickness and band sections with a lesser band thickness are obtained over the length of the metal band. The invention also pertains to a device for flexibly rolling a metal band and which includes a first working roll and a second working roll, wherein a roll gap, through which the metal band can be guided in order to be rolled, is formed between the first working roll and the second working roll, and wherein the size of said roll gap can be varied in such a way that band sections with a greater band thickness and band sections with a lesser band thickness are obtained over the length of the metal band.
2. Description of the Related Art
A flexible rolling method for manufacturing metal bands with band thicknesses that differ over its length in a defined fashion is already known from practical applications and characterized by the fact that the roll gap, i.e., the distance between the first working roll and the second working roll, is varied in a targeted fashion during the rolling process in order to obtain different band thicknesses over the length of the metal band. This can be realized indirectly, namely in the form of changing the deformation resistance of the material by heating or cooling the metal band and correspondingly changing the spring travel of the roll stand during the rolling process. In this case, the temperature of the material to be rolled may lie below or above the recrystallization temperature. However, the roll gap can also be varied directly with the aid of at least one working roll, i.e., by displacing a working roll perpendicular to the rolling direction.
In flexible rolling processes, band sections with, as described above, different band thicknesses are rolled. These band sections may be connected to one another by different inclines such that there exist many options for realizing the band thickness profile. The purpose of flexible rolling processes is to obtained manufacturing rolled products with cross-sectional shapes that are optimized with respect to their load carrying capacity and/or weight. Flexible rolling processes allow a faster manufacture of metal bands with a defined thickness profile in the longitudinal rolling direction which is individually adapted to the respective load bearing capacity for each component. After the band is correspondingly treated, these metal bands are separated into billets. Billets manufactured in this fashion are not only suitable for the automotive industry, but also for the aeronautical and aerospace industry, as well as wagon building. These billets can be formed by corresponding additional processing steps, e.g., deep-drawing, stretch-forming, internal high-pressure forming or high-pressure sheet forming. The manufacture of the profiles in only one step significantly contributes to the high economic potential of this manufacturing technology. The technological advantages can, in particular, be seen in the constant material properties of the material to be rolled, the applicability to all rollable materials and the high flexibility of the manufacturing method.
Flexible rolling methods are usually designed such that the metal band is rolled from coil to coil. However, other variations, e.g., coil to billet or billet to billet, are also known. In the rolling from coil to coil, the band tension caused by the coiler favorably influences the rolling process and contributes to a significant improvement in the surface evenness of the finished metal band in the longitudinal direction, i.e., in the rolling direction. In other respects, the flexible rolling from coil to coil simultaneously ensures a high productivity because the thickness profiles are continuously produced in the metal band.
In the manufacture of automobiles, the permissible tolerances with respect to the component geometry and/or the required surface evenness, as well as the particularly high surface quality associated therewith, become continuously stricter. This means that flexibly rolled billets are required which have an asymmetric band thickness profile. If a billet or a metal band has an asymmetric band thickness profile, a greater band thickness transition is realized on one side of the metal band than on the other side when a band section with greater band thickness transforms into a band section with lesser band thickness, and vice versa. In borderline instances, one side of the metal band does not contain any band thickness transitions at all, i.e., it is completely plane. The following description exclusively refers to metal bands with asymmetric band thickness profiles, wherein billets with asymmetric band thickness profiles are also covered by this term.
In flexible rolling methods known from the state of the art, the forming zone is defined by the distance between the working rolls on one hand and by the working roll diameters on the other hand. Due to significantly different flow resistances of the metal band in the longitudinal direction and in the transverse direction, the vertically displaced material essentially flows entirely in the longitudinal direction and not in the lateral direction. When using conventional working rolls with identical diameters, the forming zone in the roll gap lies symmetric to the central plane of the metal band. This means that the material of the metal band is uniformly stretched in the longitudinal direction over the entire cross section if the different translational motions are neglected. Metal bands with symmetric band thickness profiles cannot be produced in this fashion.
Published German Patent Application 2 245 650 discloses a method for manufacturing metal bands that contain band sections with an asymmetric band thickness profile. In this method, stepped sheets are manufactured in the reversing mode by means of hot-rolling while observing a rolling end temperature between 850° C. and 1050° C. If the initially symmetric metal band is transported onto the roller table that follows the roll stand beforehand with its band section of greater band thickness, the region of lesser band thickness is lowered until it contacts the rollers of the roller table. Such a lowering also takes place in the transition between the region with a greater band thickness and the region with a lesser band thickness such that the undersides of the region with a greater band thickness, of the transition region and of the region with a lesser band thickness form an essentially straight line. The disadvantages of this method can be seen in the fact that it is limited to hot-rolling processes, and that the yield is relatively low—due to the complicated interruption of the rolling process.
In another method known from the state of the art, asymmetric band thickness profiles are obtained due to the fact that individual beveled slabs are welded to one another and subsequently rolled plane. However, the asymmetric band thickness profile is only obtained after the welded slabs are separated. The disadvantage of this method can be seen in the required expenditure of force and labor which is twice as high in this case.
SUMMARY OF THE INVENTION
The present invention is based on the objective of providing a method and a corresponding device for flexibly rolling a metal band which make it possible to easily obtain an asymmetric band thickness profile in cold-rolling processes and hot-rolling processes.
The method in accordance with the present invention for attaining the above-mentioned objective is characterized by the fact that, in order to obtain band sections with a lesser band thickness, the time of contact between each point on the circumference of the first working roll and the metal band is shorter than the time of contact between each point on the circumference of the second wo
Böhlke Peter
Ebert Alexander
Hauger Andreas
Kopp Reiner
Muhr und Bender KG
Nixon & Peabody LLP
Safran David S.
Tolan Ed
LandOfFree
Method and device for flexibly rolling a metal band does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for flexibly rolling a metal band, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for flexibly rolling a metal band will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3110649