Cleaning and liquid contact with solids – Apparatus – Automatic controls
Reexamination Certificate
2000-09-01
2003-08-26
Stinson, Frankie L. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
Automatic controls
C134S06400P, C134S12200P, C134S186000
Reexamination Certificate
active
06609530
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process and apparatus for post-treatment of a metal strip by spraying the metal strip with a rinsing liquid to prevent staining when the strip is stopped. More particularly, the invention relates to a rinsing process where the metal strip is completely covered with liquid when the metal strip is at a standstill. In addition, the invention refers to a device for implementing the process.
BACKGROUND OF THE INVENTION
The pickling of steel is a process for removing scale from the surface of the steel that is present after various forming operations. Continuous sheets of steel are typically carried through several acid baths by immersing the strip completely in the baths for sufficient time to remove the scale. It is necessary to remove the acid residue from the steel after the pickling step to prevent corrosion, staining or spotting of the surface.
Pickling plants for treating a continuous steel strip usually include a strip rinsing facility downstream of the acid pickling stage in order to remove any residual pickling acid still adhering to the surface of the strip as the strip exits the pickling section. This rinsing process can be implemented by spraying the rinsing liquid directly onto the strip. Alternatively, the strip can be rinsed by pulling the strip through a bath of the rinsing liquid. In plants where the rinsing liquid is sprayed through nozzles directly onto the strip, the strip surface suffers serious discoloration due to oxidation if the air and rinsing water are allowed to act on the strip simultaneously during prolonged stoppages of the strip movement through the rinse station. In order to alleviate this situation, it has been suggested that the rinsing liquid be applied through nozzles and that the station be flooded with the rinse liquid when the forward movement of the strip is interrupted. The station is flooded to a level to completely cover the steel strip, thereby preventing oxygen from contacting the steel strip during the stoppage. Complete immersion of the strip reduces the staining on the strip when the strip is stopped.
Such processes and devices are known, for example, in AT 404 472 and EP 788 843. These patents disclose closing a drain valve of the rinsing tank when the strip comes to a standstill. As a result, the rinsing tank fills up to an overflow edge located above the strip. The disadvantage here, however, is that it takes a relatively long time for the tank to fill, and thus, oxidation may still occur on the strip surface before the strip is completely immersed in the rinse liquid.
In order to remedy this disadvantage, EP 788 843 discloses re-routing the rinsing liquid feed from the nozzles to an inlet specially provided for this purpose when the strip comes to a standstill. Nevertheless, the time elapsing before the rinsing tank has filled is also fairly long in this case, thus the risk of discoloration due to oxidation remains.
SUMMARY OF THE INVENTION
The present invention is directed to a process and apparatus for rinsing a metal strip of material passing through a rinsing station while preventing corrosion and staining of the metal strip. More particularly, the invention is directed to a process and apparatus for spraying a rinse liquid onto a continuously moving metal strip and flooding the rinse station during stoppage of the advance of the metal strip. The rinse station is flooded quickly to cover the strip and prevent oxidation.
Accordingly, a primary object of the invention is to provide a process and apparatus for rinsing a metal strip while reducing the risk of oxidation and staining of the metal strip.
Another object of the invention is to provide a process and apparatus for rinsing a strip material and flooding the strip material with a rinse liquid using equipment that is economical and easy to assemble.
Another object of the invention is to provide a process and apparatus for rinsing a strip material with a rinse liquid where the advancing movement of the strip material is monitored and where the rinse station is quickly flooded with the rinse liquid when a stoppage of the strip material is detected.
A further object of the invention is to provide a process and apparatus for rinsing a strip material by spraying a rinse liquid onto the moving strip material and quickly immersing the strip material in a pool of the rinse liquid when the strip material is at a standstill.
Still another object of the invention is to provide a process and apparatus for rinsing a strip material by carrying the strip material from an inlet end to an outlet end of a rinse tank and closing the inlet and outlet ends of the rinse tank when the strip material is at a standstill to form a pool of the rinse liquid in the rinse tank and to immerse the strip material in the rinse liquid.
A further object of the invention is to provide a process and apparatus for rinsing a strip material by carrying the strip material between spaced apart pinch rollers in a rinse tank and closing the gap between the pinch rollers and the rinse tank when the strip material is at a standstill to prevent drainage of the rinse liquid in the tank and to form a pool and immerse the strip material in the rinse liquid.
Another object of the invention is to provide a process and apparatus for rinsing a strip material by spraying a rinse liquid in a rinse tank where the rinse tank has a relatively small volume so that the rinse tank can be flooded and the strip material can be immersed in the rinse liquid quickly when the strip material is at a standstill.
Still another object of the invention is to provide a process and apparatus for rinsing a strip material in a spray rinse tank having pinch rollers at an inlet end and an outlet end and pneumatically operated seals for closing a gap between the pinch rollers and the rinse tank to present draining of the rinse tank and to flood the strip material in a pool of the rinse liquid.
A further object of the invention is to provide a process and apparatus for rinsing a strip material by passing the strip material through a spray rinse tank having pinch rollers at an inlet end and an outlet end and hydraulically operated seals for closing a gap between the pinch rollers and the rinse tank to prevent draining of the rinse tank and to flood the strip material in the rinse liquid.
Another object of the invention is to provide a process and apparatus for rinsing a steel strip material by carrying the strip between opposing pinch rollers for supporting the strip and providing a rinse tank having a bottom wall closely spaced to the strip and extending between the pinch rollers for defining a flooding zone.
A further object of the invention is to provide a process and apparatus for rinsing a strip material in a spray rinse tank having a detector for detecting the speed of the strip material passing through the rinse tank and a delay mechanism for flooding the rinse tank with a rinse liquid after a predetermined time period after the strip material has come to a standstill.
A further object of the invention is to provide a process and apparatus for rinsing a steel strip in a spray rinse liquid about 5 seconds to about 2 minutes after the advance of the strip is stopped.
Another object of the invention is to provide a process and apparatus for rinsing a strip material having a plurality of spaced rinse tanks and a pair of pinch rollers positioned between adjacent rinse tanks for supporting the strip material where the rinse tanks have movable seals for contacting the pinch rollers to close the rinse tanks and form a pool to immerse the strip material in the rinse liquid.
These and other objects of the invention are basically attained by providing a process for rinsing a strip material comprising: feeding a strip material through a rinse station, spraying a rinse liquid onto the strip material within the rinse tank; and detecting a stoppage of the strip within the rinse station and closing the inlet and outlet of the rinse tank to form a rinse liquid pool in the rinse tank having a depth to immers
Andritz AG
Roylance Abrams Berdo & Goodman L.L.P.
Stinson Frankie L.
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