Metal founding – Process – With measuring – testing – inspecting – or condition determination
Reexamination Certificate
2001-10-01
2003-06-24
Dunn, Tom (Department: 1725)
Metal founding
Process
With measuring, testing, inspecting, or condition determination
C164S004100, C164S476000, C164S477000, C164S154400, C164S154700, C148S320000, C148S661000, C148S541000
Reexamination Certificate
active
06581672
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems and methods for providing steel strip to order, and more specifically to systems and methods for converting customer-specified steel strip requirements to process operating parameters for controlling a continuous strip casting process operable to produce the customer-specified steel strip product.
BACKGROUND OF THE INVENTION
The conventional steel industry process for fulfilling a customer's order for a steel product with particular mechanical, dimensional and finish properties is complicated and time-consuming, and may typically require 10 or more weeks to accomplish. Referring to
FIG. 1
, for example, a flowchart is shown illustrating a flow of one conventional process
10
for producing a customer-ordered steel strip product, wherein the term “strip” as used herein is to be understood to mean a product of 5 mm thickness or less.
Process
10
begins at step
12
where the steel manufacturer receives the customer order, typically set forth in terms of mechanical (e.g., yield strength), dimensional and finish requirements for the steel strip product as well as a desired quantity. Thereafter at step
14
, the steel manufacturer determines from the customer order the particular steel chemistry requirements for achieving the product's specified properties. The chemistry requirements are selected from a large recipe list of steel chemistries that is available (and in many cases dates back to ingot casting/hot rolling technology where chemistry was the prime determinant of mechanical and finish properties). Thereafter at step
16
, the steel manufacturer determines casting parameters corresponding to operating parameters and/or set points for a steel casting process that will be used to produce steel slabs from molten steel formed in accordance with the steel chemistry requirements. At step
18
, the steel manufacturer determines downstream slab processing requirements, initially focusing on achieving the customer's dimensional requirements such as thickness etc and then working through additional downstream processing steps that may be required to achieve the final product properties. Such downstream slab processing requirements may include, for example, any one or combination of (a) slab reheat parameters corresponding to hot mill furnace operating parameters and/or set points for hot strip mill processing, (b) hot rolling parameters corresponding to mill rolling operating parameters and/or set points for hot strip mill processing, (c) cold rolling parameters corresponding to pickling and cold rolling operating parameters and/or set points for cold mill processing, and (d) heat treatment parameters corresponding to heat treatment operating parameters and/or set points for heat treatment.
From step
18
, process
10
advances to step
20
where the steel manufacturer produces a batch of molten steel in accordance with the chemistry requirements for the specified steel product and casts the steel product into slab stock in accordance with the casting parameters established at step
16
. Oftentimes, customer's orders (which can be as small as 5 tonnes) are batched together until there are sufficient orders to fill one steelmaking heat—typically 100 to 300 tonnes depending on the specific steel plant capacity. This adds further delay to the time that a particular customer's order can be filled, thereby extending the total time for production well in excess of 10 weeks. In any case, process
10
advances from step
20
to step
22
where the slab stock is reheated and hot rolled at hot strip mill, in accordance with the slab reheat and hot rolling parameters established at step
18
, to produce steel coil stock of a predefined thickness. Thereafter at step
24
, the coil stock is pickled and cold rolled at a cold mill in accordance with any pickling and cold rolling parameters established at step
18
to reduce the thickness of the coil stock to a customer-specified thickness and also to achieve desired properties. Finally, at step
26
the coil stock is heat treated in accordance with any heat treatment parameters established at step
18
to anneal the coil stock such that it meets the requirements of the customer's order.
Conventional steel strip production of the type just described necessitates the production of many different steel grades (typically, in excess of 50) that are first cast into slabs and then processed through complex hot rolling schedules in hot strip mills that produce product in thicknesses as low as 1.5 mm with yield strengths generally in the range 300 to 450 MPa. If the customer requires thinner material or properties outside this range, subsequent processing involving pickle lines, cold reduction mills and annealing furnaces is required.
A primary drawback associated with the conventional steel strip production process just described is the lengthy time period; typically 10 or more weeks, required to produce the steel product that satisfies the customer order. What is therefore needed is an improved steel strip production process that is more responsive to customer needs by greatly reducing the time required to produce customer-specified steel strip product.
SUMMARY OF THE INVENTION
The foregoing shortcomings of the prior art are addressed by the present invention. In accordance with one aspect of the present invention, a method is provided comprising the steps of receiving an order for a steel product including customer-specified requirements relating to said product, mapping said customer-specified requirements to a number of process parameters for controlling a continuous strip steel casting process to produce said steel product, and displaying said number of process parameters on a process change report to an operator of said continuous strip steel casting process.
In accordance with another aspect of the present invention, a method is provided comprising the steps of receiving an order for a steel product including customer-specified requirements relating to said product, mapping said customer-specified requirements to a number of process parameters for controlling a continuous strip steel casting process to produce said steel product, and controlling said continuous strip steel casting process based on said process parameters to produce said steel product.
In accordance with yet another aspect of the present invention, a method is provided comprising the steps of controlling a continuous strip steel casting process based on a set of predefined process parameters to produce a first steel product, receiving an order for a second steel product including customer-specified requirements relating to said second steel product, mapping said customer-specified requirements to a set of new process parameters for controlling said continuous strip steel casting process to produce said second steel product, and substituting said set of new process parameters for said set of predefined process parameters without interrupting said continuous strip steel casting process such that said continuous strip steel casting process immediately switches from producing said first steel product to producing said second steel product.
In each of the foregoing methods according to the present invention, the customer-specified requirements may include a specified steel grade and finish and/or a specified strip thickness, and the process parameters for controlling the continuous strip casting process to produce the customer-specified steel product may include any one or combination of casting speed of the continuous strip casting process, as-cast steel thickness of the steel strip, percentage of hot reduction of the steel strip, cooling rate of the steel strip and coiling temperature of the steel strip and hot rolling temperature range for hot reduction of the steel strip.
The present invention provides an improved method of providing steel strip to meet customer's orders.
The present invention also provides an improved method of substantially reducing the turnaround time bet
Blejde Walter
Mahapatra Rama
Mukunthan Kannappar
Strezov Lazar
Dunn Tom
Lin I.-H.
Nucor Corporation
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