US 20090090566 A1
A steel coil weighing apparatus includes a base having a structure capable of supporting the weighing apparatus and an article to be weighed and having a base portion capable of contact with a load cell, a platform positioned above the base and having a platform portion capable of contact with a load cell, at least one load cell positioned between the base portion and the platform portion and capable of providing a signal corresponding to the weight of an article to be weighed, and at least one guide capable of aligning the base and the platform.
1. A weighing apparatus comprising:
a base having a structure capable of supporting the weighing apparatus and an article to be weighed, and having at least two base portions capable of contacting a load cell;
a platform positioned above the base and having at least two platform portions capable of contacting a load cell and readily removable from the base with minimal tools to enable removal of the load cells;
at least two load cells each positioned between at least one base portion and at least one platform portion and capable of providing a signal corresponding to the weight of the article to be weighed; and
at least two guides offset from the load cells capable of aligning the base and the platform, each guide having a portion operably positioned on the base and a corresponding portion operably positioned on the platform.
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This invention relates to weighing systems, and more particularly to an apparatus and method for weighing steel coils.
Steel coils, and other similar coils, are weighed at various times during their production and distribution using coil scales or other coil weighing apparatuses. The coil weighing apparatuses may be located in steel mills and other locations where the environment may include heat, dust, vibration, and other factors. Further, coils are heavy, weighing up to 60,000 pounds (27,000 kilograms) or more. In a production environment, a coil weighing apparatus incurs ongoing maintenance costs due to use and environment.
Coil weighing apparatuses use load cells for measuring the weight of a coil. The accuracy and longevity of load cells may be reduced by factors such as uneven loading, impact shocks to the cell, overloading, and other use and environmental considerations. When placing a heavy coil on a coil scale, the coil may be dropped onto the scale, not placed evenly onto the scale, or may be misaligned resulting in the coil rolling or bouncing and possibly causing deformation of the scale and load cells. For this reason, maintenance and replacement of load cells in a weighing apparatus has been necessary.
Maintenance of coil weighing apparatuses may include changing load cells due to damage or for routine replacement. Additionally, when past coil weighing systems were subjected to deformation, shims were placed under portions of the scale to maintain proper alignment and attachment of the load cells. Other periodic or occasional maintenance and repair may be required, such as lubrication of moving parts.
However, past coil weighing systems have been difficult to assemble, repair, and maintain. For maintenance or repair of past coil scales or weighing systems, the entire coil weighing system had to be lifted out and disassembled, thereby increasing maintenance costs. Some past coil weighing systems required as much at twelve hours for disassembly and reassembly. Increased maintenance time resulted in reduced operational time for both the scale and the production operation utilizing the coil scale.
Some past weighing systems included a base and a weighing platform where certain platform members were integrally connected to the base. In the past, such integration weighing systems were thought necessary for achieving the rigidity needed for weighing heavy steel coils. Additionally, integrated structures were thought necessary to maintain alignment of the weighing assembly during operation and to resist the forces created when steel coils were placed upon the weighing apparatus.
The platform integrated with the base of prior weighing apparatuses complicated maintenance tasks and increased maintenance costs. When platform members were integrated with the base, additional time was required to disassemble the weighing apparatus for service or repair. This additional time increased the maintenance costs and also decreased the utilization of the weighing apparatus. Because a weighing apparatus may be an essential component of the steel production process, the additional maintenance time also decreased the productivity of an entire production line.
Further, the weight capacity and measurement accuracy of a coil weighing system depends in part upon the selection of the load cell. Thus, in steel coil production operations producing coils of different sizes and weights, certain load cells had to be changed to accommodate different weight coils. With load cells being difficult to change in past coil weighing systems, adapting to different size coils was difficult and time consuming, if even possible. Past weighing apparatuses had to be disassembled and reassembled, risking damage to the load cells and other components in the weighing system. In the past, it was impractical to use one coil weighing apparatus when different sizes or weights of coils needed to be weighed.
Certain portions of coil weighing apparatuses in the past have also been susceptible to corrosion and deterioration. Steel coils have been produced from pickled, tempered, cold rolled, galvanized, and other types of steel. Additionally, the steel formed into steel coils may have been coated with other types of coatings and chemical treatments. The coatings and other chemicals used during the steel manufacturing process have contacted the components of prior steel coil weighing systems. As a result, care had to be taken to protect past coil weighing apparatuses from corrosion adding to the cost of the weighing system.
Other weighing systems have emphasized the need to protect load cells from damage (see U.S. Pat. No. 5,739,478). Such past systems have required disengaging the load cells prior to placing an article to be weighed on a weighing platform. In this fashion, transitional or shock loads could be dissipated prior to engagement of the load cells. While this design may have protected the load cell from a shock load, these past systems added complexity and cost to the design and maintenance of the weighing system.
There continues to be a need for weighing apparatuses with improved maintenance and operational costs.
The disclosed steel coil weighing apparatus comprises a base having a structure capable of supporting the weighing apparatus and an article to be weighed and having a base portion capable of contact with a load cell, a platform positioned above the base and having a platform portion capable of contact with a load cell, at least one load cell positioned between a base portion and a platform portion capable of providing a signal corresponding to the weight of an article to be weighed, and at least one guide capable of aligning the base and the platform.
Also disclosed is a method of weighing a steel coil comprising assembling a steel coil weighing apparatus, aligning the platform and the base, the alignment being accomplished by the guide, positioning a steel coil on the platform, receiving the signal provided by the load cell, and calculating the weight of the steel coil.
The present coil weighing apparatus is described below with reference to the following the drawings and figures:
Referring generally to
The base 20, as shown in
The platform 30 is positioned above the base 20 and capable of supporting a steel coil 12 to be weighed. The platform 30 may have a platform top portion 32 positioned above a platform bottom portion 34. An access hole 36 may be provided through the top portion 32. The platform 30 is sized to accommodate a steel coil to be weighed. In one example, the platform 30 may be about 22 inches (about 56 centimeters) by about 35 inches (about 89 centimeters). As shown in
Each load cell 40 may be positioned between the base top portion 22 and the platform bottom portion 34. The load cell 40 may be affixed to the base top portion 22. Alternately or in addition, the load cell 40 may be affixed to the platform bottom portion 34. We have found that affixing one side of the load cells to either the base 20 or platform 30 and allowing the opposite side of the load cell to remain unattached provides additional load cell life. Alternately, a compressive load cell may be used that is neither affixed to the base nor the platform.
In one example shown in
The load cell 40 may an analog or digital load cell. Alternatively, the load cell may be a strain gauge, electromagnetic force senor or other type of weight sensing device known to those skilled in the art. The load cell 40 may be moisture protected and may be coated with a corrosion resistant coating. The load cell 40 may be a low profile load cell to reduce the overall height of the steel coil weighing apparatus 10. Additionally, the load cell may be configured to reduce inaccuracies caused by off-center or side loading.
The coil weighing apparatus 10 may include one load cell 40, or may have more than one load cell, such as two, or three or more. Multiple load cells 40 may be used to increase the measurement capacity of the weighing apparatus 10. Additionally, multiple load cells 40 may allow for increased accuracy during the measurement of greater weight articles. As shown in
The capacity of the load cell 40 is one consideration in determining the measurement capacity of the weighing apparatus 10. It may be desired to provide a measurement capacity greater than the weight of the heaviest steel coil to be weighed to provide a more robust apparatus. If a steel coil is dropped on the weighing apparatus, the transitional or shock load experienced by the load cells may be greater than the weight of the coil. Additionally, if a steel coil 12 rolls on the platform the load cell 40 may experience a force greater than the weight of the steel coil. As an article being placed on the weighing apparatus may not be exactly centered on the weighing apparatus 10 as it is lowered onto the platform 30, shock loads may be generated by the article rolling or bouncing upon the weighing apparatus. The load cells 40 and guides 50 may be selected accommodate the higher forces that may be experienced during this transitional period. In one example, the coil weighed may be about 60,000 pounds (about 27,000 kilograms); however, the capacity of the weighing apparatus may be selected as 150,000 pounds (about 68,000 kilograms) as determined by the ratings of the guide 50 and the load cell 40.
The steel coil weighing apparatus 10 may have one or more guides 50 having portions capable of aligning the platform 30 and the base 20. The guide 50 may be positioned between the base 20 and the platform 30 such that when the weighing apparatus is assembled the guide may align the platform 30 over the base 20. During assembly and use of the weighing apparatus, the guide 50 enables the platform 30 to move in a direction along the guide.
As shown in
An aperture 28 may be positioned in the base 20, the platform 30, or both to provide a location for attachment of the guide 50. The guide sleeve 54 may be affixed in the guide aperture 28. In one alternate, the guide aperture 28 is formed to be the guide sleeve 54. The guide shaft 52 may be attached the base 20, or alternately the platform 30, using a fastener, such as but not limited to a roll pin 56, a snap ring or set collar 58, screws and/or bolts, welding, other fasteners capable of retaining the guide shaft 52, or a combination thereof. The fastener may serve to stabilize the guide shaft 52 during operation of the weighing apparatus. Additionally, the fastener may retain the guide shaft 52 when the platform 30 and base 20 are disassembled for maintenance or repair. The length of the guide shaft 52 may be selected to operatively connect the base 20 and the platform 30. The length of the guide shaft 52 may also be selected so as to align the platform over the base 20 during assembly and operation of the weighing apparatus. As shown in
The guide 50 may include a bushing, a slide bearing, linear bearing, or other bearing structures. The guide 50 may utilize a polymer on bearing or sliding surfaces to reduce friction as the platform 30 is depressed during weighing operations or being removed from the base. The guide shaft 52 may have any suitable cross sectional shape, such as but not limited to circular, rectangular, t-shape, or other cross sectional shape capable of providing bearing surfaces. The guide shaft 52 may be made from suitable steel such as a stainless steel and may be corrosion resistant and capable of operating in the environment of the weighing apparatus. The guide sleeve 54 may have bushings and/or bearings capable of operably engaging the bearing surfaces of the guide shaft 52.
In one example, four guides 50 may be used where at least one guide is a precision guide and remainder of the guides are compensating guides. In this configuration, the precision guide may restrict movement of the guide sleeve 54 to substantially one direction along the guide shaft 52. The precision guide may thus be used to maintain the vertical relationship between the platform and the base. The precision guides reduce non-vertical forces being applied to the load cells 40. The precision guide may be a precision linear bearing. The compensating guides restrict movement of the guide sleeve 54 to the direction along the guide shaft 52, but also allow limited lateral movement to assist with absorbing and dampening shock and transitional loads. When a steel coil 12 is placed on the platform 30 the coil may roll or bounce. The compensating guides may enable some lateral movement to accommodate the forces associated with this movement of the steel coil 12 to reduce damage to the load cells 40 and the weighing apparatus 10. Additionally, the compensating guides may accommodate misalignment of the platform 30 and base 20 during assembly so as to avoid binding of the guides 50 when the weighing apparatus 10 is assembled. The compensating guides may be self-aligning or compensating linear bearings.
The weighing apparatus 10 may have at least two guides, where at least one guide includes a precision linear bearing and at least one guide includes a self-aligning or compensating linear bearing.
As shown in
The weighing apparatus 10 may be reassembled by lowering the platform 30 such that the guide shaft 52 engages the guide sleeve 54 to operatively connect the platform 30 and the base 20. The guide shaft 52 or the guide sleeve 54, or both, may provide a lead-in taper to assist in aligning the platform 30 over the base 20 during reassembly. The reassembly of the weighing apparatus 10 may also therefore reduce the total required maintenance time and may increase the operational efficiency and utilization of the system.
Load cells 40 may be changed or removed without fully disassembling the platform 30 from the base 20. The bolts 42 may be removed while the platform 30 is at rest over the base 20. Then, the platform may be lifted about 1 or 2 centimeters to separate the platform 30 from the load cells 40, enabling the load cells to be removed. In this way, the time to replace the load cell is reduced, thereby reducing downtime and cost.
Operation of the coil weighing apparatus 10 may begin when an article, for example a steel coil 12, is positioned onto the platform 30. When a coil or other article is positioned upon the platform 30, the platform presses on the load cells 40. The load cells 40 generate a signal corresponding to the weight of the article, and the weight of the article may then be calculated. In one example, a single load cell 40 may be used and the weight of the article calculated from that signal provided. In another example, three load cells 40 may be used and the weight of the article may be calculated from the signals of the three load cells. Additionally, the weight of the platform 30 may be subtracted from the weight measured by the load cells 40 to determine the true weight of the article. The weight of the article may be calculated by a computer or other machine and used in a production process; however, the weight may also be simply presented for display to an operator. The coil weighing apparatus 10 may also provide for temperature compensation to reduce errors in the calculated weight of the article caused by expansion or contraction of the load cell. Temperature compensation may be a feature of the load cell 40 or may be performed through post-processing of the signal produced by the load cell. Additional compensation for temperature, vibration, or other environmental factors may also be performed. Methods for compensating for temperature drift and other errors associated with weighing articles are well known to those of skill in the art.
One or more weighing apparatuses 10 may be utilized in a coil weighing system 5, as shown in
The coil weighing system 5 may also include a selection of platforms 30. Different platforms 30 may be desired for measuring coils 12 of various sizes. A weighing system 5 adapted to employ a variety of platforms 30 may be easily reconfigured for weighing different coil sizes, thereby reducing change-over time of the system and reducing maintenance costs. The coil weighing system 5 may also include a variety of load cells 40 for weighing coils of different weights. A coil weighing system 5 adaptable to various combinations of coil weight and size may reduce the operational and maintenance costs of such a system relative to past weighing systems. The coil weighing system 5 may further include a computer, programmable logic controller, or other processor (not shown) or equivalent equipment for controlling the weighing system and recording and/or analyzing load cell signals and measurements.
While the invention has been described with detailed reference to one or more embodiments, the disclosure is to be considered as illustrative and not restrictive. Modifications and alterations will occur to those skilled in the art upon a reading and understanding of this specification. It is intended to include all such modifications and alterations in so far as they come within the scope of the claims, or the equivalents thereof.