Patent Application
20130047811
1. Field of the Invention
This invention relates to rolling mills in which billets are hot rolled into multi bar process sections that are then slit into individual bars, and is concerned in particular with the provision of an improved apparatus and method for slitting such process sections.
2. Description of Related Art
In conventional mill installations, it is known to roll heated billets into process sections comprised of multiple interconnected bars. The process sections are then pushed by the rolling action of a preceding roll stand through slitting guides having pairs of free wheeling slitting rollers configured to slit the process sections into individual bars. Experience has shown, however, that the force required to push the process sections through the slitting guides can distort and damage bar front ends, in addition to accelerating frictional wear of the slitting rollers. The resistance to the process section being pushed through the guides can also lead to unequal areas of the bars leaving the slitting guides. This force increases with larger process sections,
Briefly stated, exemplary embodiments of the present invention relate to an improved slitter having first and second pairs of upper and lower slitting rollers that are rotatably driven in directions urging the process section along the mill rolling line and through the slitter. The driving force of the slitting rollers eliminates the need to push the process section into and through the slitter, thus avoiding distortion and damage of the bar front ends, while also beneficially reducing frictional wear of the slitting rollers. The size of the rollers on the driven slitter can be larger than on a non-driven slitter, since there is no need to accelerate the rollers when the process section enters. This additionally results in longer life on the rollers, and improves slitting conditions by providing a larger bite angle.
Preferably, a gear drive mechanically couples the upper and tower slitting rollers of each pair to a single power source.
Advantageously, the upper and lower slitting rollers of each pair are carried respectively on upper and lower roller shafts, and the gear drive comprises an upper drive shaft carrying an upper drive gear in meshed relationship with driven gears on the upper roller shafts, and a lower drive shaft carrying a lower drive gear in meshed relationship with driven gears on the lower roller shafts, with the upper and lower drive gears being in meshed relationship, and with one of the drive shafts being connected to the single power source.
Advantageously, the spacing between the upper and lower roller shafts of at least one and preferably both of the first and second pairs is adjustable, and preferably such adjustments are performed symmetrically with respect to the rolling line.
Slitters in accordance with the present invention operate in two stages to slit process sections comprising four, five or six interconnected bars.
In one exemplary embodiment, the process section has four bars, the profiles of the first pair of slitting rollers are configured to separate the process section into two sets of two connected bars, and the profiles of the second pair of slitting rollers are configured to separate the bars of each of said sets.
In another exemplary embodiment, the process section has four bars, the profiles of the first pair of slitting rollers are configured to separate the outermost bars on each side of the process section from the two middle connected bars, and the profiles of the second pair of slitting rollers are configured to separate the two middle bars.
In stilt another exemplary embodiment, the process section has five bars, the profiles of the first pair of slitting rollers are configured to separate the middle bar from two outer sets of two connected bars, and the profiles of the second pair of slitting rollers are configured to separate the two bars of the outer sets.
In another exemplary embodiment, the process section has six bars, the profiles of the first pair of slitting rollers are configured to separate the process section into three sets of two connected bars, and the profiles of the second pair of slitting rollers are configured to separate the bars of each set.
These and other embodiments, objects, features and advantages of the present invention will become more apparent upon reading the following specification in conjunction with the accompanying drawing figures.
To facilitate an understanding of embodiments, principles, and features of the present invention, they are explained hereinafter with reference to implementation in illustrative embodiments.
The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present invention.
As herein employed, the term “bars” is to be interpreted as including not only the rounds illustrated in the drawings, but also other bar products, including for example squares, hexes, angles and flats.
Referring now to the figures, wherein like reference numerals represent like parts throughout the views, embodiments of the present invention will be described in detail.
With reference initially to
The slitting apparatus 10 comprises first and second pairs of upper and lower slitting rollers 16a, 16b and 18a, 18b positioned sequentially along the rolling line X. The slitting rollers of each pair are arranged to engage opposite sides of the process section 12 as it move longitudinally along the rolling line. In the illustrative embodiment depicted in
The upper and lower slitting rollers 16a, 16b of the first pair are carried respectively on upper and lower roller shafts 20a, 20b. Likewise, the upper and lower slitting rollers 18a, 18b of the second pair are carried on upper and lower roller shafts 22a, 22b.
A drive means rotatably drives the slitting rollers in directions indicated diagrammatically by the arrows in
Preferably, the drive means serves to rotatably drive slitting rollers at peripheral velocities that exceed the speed of the process section moving along the rolling line. Preferably, such peripheral velocities exceed the speed of the process section by about 2-3%.
The slitting apparatus further comprises adjustment means for adjusting the spacing between the upper and lower roller shafts 20a, 20b and 22a, 22b. As can best be seen in
The first pair of slitting rollers 16a, 16b have profiles configured to break the connection between at least some of the bars of the process section 12 while allowing the connections between other bars to remain intact, and the second pair of slitting rollers 18a, 18b have profiles configured to break the remaining intact connections between the other bars of the process section.
For example, and as depicted schematically in
As shown in
In each case, the rotatably driven slitting rollers serve to urge or propel the process section forwardly, thereby eliminating the need to push the process section into and through the slitter. This safeguards the bar front ends from damage, minimizes frictional wear of the slitting rollers, and allows large diameter slitting rollers to be employed, which also benefits the slitting process. Symmetrical adjustment of the roller shafts enables operating personnel to adjust for wear of the slitting rollers, and to accommodate different sizes of process section.
