Patent Application
20130075515
1. Field
Embodiments of the present invention relate to rolling mill coil-forming apparatuses, often referred to as laying heads, and more particularly to replaceable laying head pathways, such as laying head pipes, in laying heads.
2. Description of the Prior Art
Rolling mill coil-forming laying head apparatuses form moving rolled elongated material into a series of helical continuous loop rings. Those rings may be further processed downstream by bundling them into coils of the helical turns. Known laying heads are described generally in U.S. Pat. Nos. 5,312,065; 6,769,641; and 7,011,264, the entire contents of all of which are hereby incorporated by reference as if fully contained herein.
As described in these patents, rolling mill laying head systems comprise a quill, pipe support and a laying head pipe. The quill and pipe support are adapted to rotate the laying head pipe such that it can receive elongated material into its entry end. The laying head pipe has a curved intermediate portion that is surrounded by the quill's flared section and an end portion that projects radially outwardly from and generally tangential to the quill's rotational axis. The rotating quill and the laying head pipe in combination conforms the rolled material into a helical curved shape. The laying head pipe may be replaced with one of a different profile and/or diameter in order to reconfigure the laying head to accommodate different dimensioned rolled material or to replace worn pipes.
Further helical profiling of the rolled material is accomplished in a rotating helical guide that includes troughs for receiving the rolled material about its outer circumference. The helical guide described in U.S. Pat. No. 6,769,641 is of segmented, sector-shaped, modular rim construction with the circumferential troughs formed within the rim sectors.
A generally annular ring or shroud, also commonly referred to as an end ring or guide ring, has a guide surface that circumscribes the laying head pipe discharge end and helical guide, so that the elongated material is confined radially as it is discharged in now fully coiled configuration to a conveyor for subsequent bundling and other processing. A pivoting tripper mechanism, including one or more tripper paddles, may be positioned at approximately the six o'clock or bottom position of the end ring/shroud distal the quill. Varying the pivot attack angle of the tripper mechanism relative to the ring/shroud inner diameter surface is useful to control elongated material coiling, for example to compensate for varying elongated material plasticity thickness, composition, rolling speed and cross sectional structure.
Laying Head Pipe Design and Operational Constraints
As previously noted the hollow laying head pipe in combination with the rotating quill and pipe support, conform the rolled material into a helical curved shape. Typically the laying head pipe is formed from a continuous length of symmetrical steel pipe or steel tubing that is bent in a forming jig by application of external heat and mechanical force to conform to the desired generally helical profile. Steel pipe or tubing is generally chosen for construction of laying head pipes for relative ease of workability into the desired final generally helical shape and relatively low material purchase cost. But commercial steel pipe or tubing have relatively low hardness: an undesirable limiting factor for rolling mill operation, productivity and maintenance.
Elongated material that is advancing at speeds up to approximately 500 feet/second (150 m/sec) is received in the laying head system intake end and discharged in a series of continuous coil loops at the discharge end. At such speeds, the hot rolled products exert a punishing effect on the laying head pipes, causing internal pipe surfaces to undergo rapid localized frictional wear and premature failure. Also, as the laying head pipes wear, their ability to deliver a stable ring pattern to the looped coil receiving conveyor at the discharge end of the laying head deteriorates. Unstable ring patterns disturb cooling uniformity and also contribute to coiling mishaps commonly referred to as “cobbling.”
For a number of years, it has been well accepted that laying head pipes with reduced bore sizes provide a number of significant advantages. By radially constricting the hot rolled products within a smaller space, guidance is improved and the ring pattern delivered to the cooling conveyor is more consistent, making it possible to roll at higher speeds. Unfortunately, however, these advantages have been offset to a large extent by significantly accelerated pipe wear due to the higher speed of the product. Also, the reduced bore size pipe can only be used with small diameter products, so it must be replaced by a larger bore size pipe for coiling of larger diameter products.
Frequent and costly mill shutdowns and preventive maintenance are required to replace prematurely worn laying head pipes and to address problems associated with elongated material cobbling. If a laying head pipe becomes so worn that it suffers a pipe wall rupture, the cobbling mishap can impact elongated material feed upstream of the laying head. From a wear resistance point of view it is desirable to form the laying head pipe inner wear surface from relatively hard low surface friction steel and further desirable to perform further surface hardening and heat treatment, but such wear treatment steps must be balanced with ease and cost of pipe fabrication.
Thus, in the past, those skilled in the art have deemed it necessary to compromise laying head pipe design and performance by employing larger bore laying head pipes and rolling at reduced speeds below the rated design speeds of the mills. The combination of larger than desired laying head pipe internal diameter and reduced rolling speeds have been implemented in order to schedule preventive maintenance pipe replacement during scheduled maintenance “downtime”. Conventional and current laying head pipes must be replaced after processing quantities of elongated material of approximately 3,000 tons or less with standard carbon steel pipe, depending on diameter, speed and product composition.
Those skilled in the art have made repeated attempts at increasing the useful life of laying head pipes for larger total processing tonnage, so that more elongated material can be processed before replacement. For example, as disclosed in U.S. Pat. Nos. 4,074,553 and 5,839,684, it has been proposed to line the laying head pipes with wear resistant insert rings that are inserted into an external laying head pipe casing. Adjoining rings within curved sections of the laying head pipe casing have discontinuity gaps that are not desirable for smooth advancement of elongated material that is being transported within the laying head pipe. U.S. Pat. No. 6,098,909 discloses a different approach where the laying head pipe is eliminated in favor of a guide path defined by a spiral groove in the outer surface of a conical insert enclosed by a conical outer casing, with the insert being rotatable within the outer casing to gradually shift the wear pattern on the inner surface of the outer casing. It is not believed that the spiral groove conical insert approach is readily compatible with all existing quill laying heads that presently incorporate laying head pipe structures.
Attempts have also been made at carburizing the interior laying head pipe surfaces in order to increase hardness and resistance to wear. However, the carburizing process requires a drastic quenching from elevated processing temperatures, which can distort the pipe curvature. The carburized layer has also been found to be relatively brittle and to temper down at elevated temperatures resulting from exposure to the hot rolled products.
The owner of this patent application has also disclosed the application of a boronized layer to the laying head pipe wear surfaces by subjecting them to a thermochemical treatment in which boron atoms are diffused into the pipe interior to increase its hardness. See Patent Cooperation Treaty Application entitled “Boronized Laying Pipe”, filed in the United States Receiving Office on Sep. 2, 2011, Serial No. PCT/US2011/050314.
The owner of this patent application has also disclosed a laying head pipe having inner and outer friction-tight engaged concentric layers in which the inner layer advances axially relative to the outer layer during laying head operation due to centrifugal forces, differences in localized thermal expansion, and thermal cycling between the layers. Thus worn sections of the laying head pipe interior advance along the pipe interior so that a “fresh” unworn surface continually replenishes the worn section. See Patent Cooperation Treaty Application entitled “Regenerative Laying Pipe”, filed in the United States Receiving Office on Sep. 2, 2011, Serial No. PCT/US2011/050283.
Accordingly, embodiments of the present invention include a rolling mill laying head pipe or other elongated structure, for retention and transport of elongated materials in a laying head, so that the elongated material can be selectively coiled. The laying head path structure may perform the functionality of a conventional laying head pipe. In aspects of the present invention, any portion of the laying head path structure or the structure in its entirety is formed by a laser sintering (LS) process. In other aspects of the present invention all or any portion of the laying head path structure comprises laser sintered superalloy. Coil forming apparatus components formed by a laser sintering process can be constructed in any three dimensional compound curve shape that can replicate the smooth, continuous curve elongated material transport path of known laying pipes, or any other desired path. Such coil forming apparatus elongated pathway/pipe component fabrication processes facilitate construction of asymmetrical structures that cannot be readily fabricated with bent symmetrical wall pipe, tubing or other conduits. The fabricated laying path structures facilitate formation of zones within the component, such as including by way of example wear-resistant zones, material stand off or material transport guide zones, or friction reducing zones. The zones can be formed during the laser sintering process, such as by substitution of different sintering material compositions during the sintering process, or coupled to other structure formed during the sintering process (e.g., ion bonded, mechanically attached by fasteners, welded, brazed, soldered, electroplated, etc.).
Another exemplary embodiment relates to a coil-forming apparatus laying head system for coiling hot rolled elongated material comprising a quill rotating about an axis, for discharging elongated material. A support is coaxial with the quill rotational axis. An elongated transport path hollow member, such as a laying head pipe, is coupled to the support, for passage of elongated material there through. The hollow member comprises a first end generally aligned with the quill rotational axis for receiving elongated material discharged from the quill, and a second end radially spaced from the rotational axis for discharging elongated material generally tangentially relative to the rotational axis. The hollow member can be constructed of combinations of ferrous and non-ferrous dissimilar materials. Any portion of the hollow transport path/pipe or the structure in its entirety is formed by a laser sintering (LS) process.
An additional exemplary embodiment of the present invention includes a method for forming an apparatus for retention and transport of elongated materials in a rolling mill coil forming laying head system comprising forming an elongated hollow pathway structure for transport of elongated materials by laser sintering superalloy material. Any portion of (or the entire) elongated pathway/pipe structure is formed by a laser sintering (LS) process.
The features of aspects of the present invention may be applied jointly or severally in any combination or sub-combination by those skilled in the art. Further features of aspects and embodiments of the present invention, and the advantages offered thereby, are explained in greater detail hereinafter with reference to specific embodiments illustrated in the accompanying drawings, wherein like elements are indicated by like reference designators.
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
After considering the following description, those skilled in the art will realize that the teachings of the present invention can be utilized in rolling mill coil-forming apparatus laying heads and more particularly to laying head elongated transport path pipes or other equivalent elongated structures for laying heads. Aspects of the present invention facilitate longer laying head path service life so that more tons of elongated material can be processed by the laying head before preventative maintenance replacement. For example, it is possible to increase the laying head elongated material processing speed so that more tons of elongated material can be processed in a production shift without undue risk of laying head path/pipe failure. Any portion of the laying head path/pipe or the structure in its entirety is formed by a laser sintering process, including laser sintering of superalloy materials.
Laying Head System Overview
Referring generally to
The laying head system 30 comprises a rotatable quill 50, a path 60 and a pipe path support 70. The path 60 defines a hollow elongated cavity to enable transport of the material M. Aspects of the present invention allow the path to comprise a laying head pipe; indeed, the path 60 may occasionally be referred to as a laying head pipe herein.
The quill 50 can have a generally horn shape that is adapted to rotate about an axis. The path 60 has a generally helical axial profile of increasing radius, with a first end 62 that that is aligned with the rotational axis of quill 50 and receives elongated material M. The path 60 has a second end that is spaced radially outwardly from and generally tangential to the quill 50 rotational axis and thus discharges the elongated material generally tangentially to the periphery of the rotating quill. The path 60 is coupled to a pipe support 70 that is in turn coupled coaxially to the quill 50, so that all three components rotate synchronously about the quill rotational axis. Quill 50 rotational speed is selected based upon, among other factors, the elongated material M structural dimensions and material properties, advancement speed S, desired coil diameter and number of tons of elongated material that can be processed by the laying head pipe without undue risk of excessive wear.
In this embodiment, as elongated material M is discharged from the second end 64, it is directed into a ring guide 80 having guide rim segments 82 into which are formed a guide trough channel 84 having a helical pitch profile, such as that described in commonly owned U.S. Pat. No. 6,769,641. As the elongated material M is advanced through the ring guide 80 it is continued to be conformed into a continuous loop helix.
As stated in the '641 patent, the segmented ring guide enables relatively easy reconfiguration of the ring guide helical diameter to accommodate different elongated materials by changing the rim segments 82 without disassembling and replacing the entire ring guide 80.
As previously noted, the elongated material M is configured into a continuous looped coil as it rides within the ring guide 80 helical trough channel 84. Ring guide 80 is coupled to the pipe support 70 and rotates coaxially with the quill 50. The helical trough 84 advancement rotational speed is harmonized with the elongated material M advancement speed S, so there is little relative linear motion speed between the two abutting objects and less rubbing wear of the trough 84 surfaces that contact the coiling material.
Stationary end ring 90 has an inner diameter that is coaxial with the quill 50 rotational axis and circumscribes the laying path/pipe 60 second end 62 as well as the ring guide 80. The end ring 90 counteracts centrifugal force imparted on the elongated material M as it is discharged from the laying head pipe 60 second end 62 and advances along the ring guide 80 helical trough channel 84 by radially restraining the material within the end ring inner diameter guide surface. High relative speed between the advancing elongated material M and the stationary end ring 90 causes rubbing wear on the end ring inner diameter guide surface.
Referring to
Laying Head Pipe Fabrication
Embodiments of the present invention include a rolling mill laying head path structure, for retention and transport of elongated materials in a laying head, so that the elongated material can be selectively coiled. Any portion of the path structure in its entirety is formed by a laser sintering (LS) process.
In known LS fabrication processes a laser is used to fuse metal particles or powders into a mass that has a desired shape by building cross-sectional layers one on top of each other in a generally axial direction on a sintering table. The table generally includes a bin of powdered metal building material onto which the laser beam is manipulated in a two-dimensional scan pattern. When the fused metal hardens sufficiently it is translated axially away from the laser scanning area an again covered with a powder layer. The additive laser sintering process builds layer upon layer and results in a three dimensional structure. Different sintering material can be employed during different stages of the additive building process so that the fabricated laying head path/pipe structure includes materials having different characteristics. For example a portion of the structure can be constructed with mild steel sintering powder material while portions that require higher wear resistance can be constructed with tungsten or so-called non-ferrous superalloys sintering powder, for example Inconel®, Waspaloy® or Hastelloy®.
Laying head components formed by a LS process can be constructed in any three dimensional compound curve shape that can replicate the smooth, continuous curve elongated material transport path of known laying head pipes, or any other desired path. Such laying head path component fabrication processes facilitate construction of asymmetrical structures that cannot be readily fabricated with bent symmetrical wall pipe, tubing or other conduits. The fabricated structures facilitate formation of zones within the component, such as including by way of example wear-resistant zones, material stand off or material transport guide zones, or friction reducing zones. The zones can be formed during the laser sintering process, such as by substitution of different sintering material compositions during the sintering process, or coupled to other structure formed during the sintering process (e.g., ion bonded, plasma sprayed, mechanically attached, welded, brazed, soldered, electroplated, etc.).
Referring to
Zones are formed in the insert 170. The formed insert 170 has a body portion 176 and necked axial ends 172, 174 that mate with corresponding necked ends 163A and 165A of the respective inner steel pipe sections 163, 165. Upstanding, mutually spaced ribs 178 are formed in a portion of the insert body 176 circumference and retain other materials in the spaced gap between ribs. The other materials subsequently may be coupled to the insert body 176 by known processes, such as for example sintering processes, plasma or vapor deposition or electro-plating.
By way of example, a hardened non-ferrous alloy, such as tungsten carbide 179A may be added between the ribs 178, projecting radially into the laying path 160 to act as a hardened wear surface interfacing with hot elongated material that is transported through the pipe. Such hardened zones 179A can be positioned selectively within the laying path structure 160 inner diameter to increase the structure's longevity. Similarly, high-temperature friction reducing materials 179B, such as graphite, can also be positioned selectively within the laying pipe inner diameter.
For all laying head elongated path structures laser sintering formed embodiments of the present invention herein, the laying path elongated structure may have a symmetrical or asymmetrical cross section, and can be fabricated in a series of adjoining sections. During the laser sintering process, the laying head elongate pathway inner diameter can be varied, such as by locally varying the wall thickness, while if desired, maintaining or varying the pathway outer diameter. The laying path elongated structure members may be fabricated from various ferrous or non-ferrous materials during the laser sintering fabrication process, including bonding or embedding ceramic particles therein. Preferred materials comprise ferrous metals, nickel based alloys, cobalt based alloys and titanium based alloys, as well as deposited nano particle coatings of any of them. The inner diameter of the path forming structure comprises ferrous or non-ferrous materials, including ceramic, nano particle material coatings, steel, or non-ferrous alloys such as stainless steel, tungsten carbide or so-called super alloys, such as for example Inconel®, Waspaloy® or Hastelloy®. Other non-ferrous metals may be substituted for the inner pathway surface layer during the laser sintering fabrication process, comprising by way of example stainless steel, tungsten carbide, and so-called super alloys, such as for example Inconel®, Waspaloy® or Hastelloy®, ceramics or nano particle layers of the above. The inner surface of the pathway that is in contact with the elongated material may be treated or coated (including nano particle coatings) to increase surface hardness, reduce friction or decrease thermal ablation.
Although various embodiments, which incorporate the teachings of the present invention, have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings.
This application claims priority under 35 U.S.C. §119(e) to co-pending U.S. Provisional Application Ser. Nos. 61/539,014, 61/539,062, and 61/539,069, filed 26 Sep. 2011; and U.S. Provisional Application Ser. Nos. 61/540,590; 61/540,602; 61/540,609; 61/540,617; and 61/540,798; filed 29 Sep. 2011, and all of which are entirely incorporated herein by reference as if fully set forth below.
| Number | Date | Country | |
|---|---|---|---|
| 61539014 | Sep 2011 | US | |
| 61539062 | Sep 2011 | US | |
| 61539069 | Sep 2011 | US | |
| 61540590 | Sep 2011 | US | |
| 61540602 | Sep 2011 | US | |
| 61540609 | Sep 2011 | US | |
| 61540617 | Sep 2011 | US | |
| 61540798 | Sep 2011 | US |
