Caster roll

The caster roll (10) is used in the manufacture of metal plate, strip, sheet, or foil. The caster roll (10) includes a cylindrical roll core (12) and at least one metal overlay (14) formed on the roll core (12). The at least one metal overlay (14) defines a plurality of cooling passages (34) for conducting a cooling medium through the at least one metal overlay (14) to cool the roll (10) during use. Additional metal overlays (16) may be formed on top of the at least one metal overlay. (14). The cooling passages (34) may also be formed in the roll core (12).

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to caster rolls used in the manufacturing of sheet material and methods of manufacturing caster rolls. More particularly, the present invention relates to an internally cooled caster roll having one or more layers of material, such as metal, formed on a roll core of the caster roll and methods of manufacturing the caster roll.

2. Description of Related Art

In the manufacture of cast aluminum plate, strip, sheet, or foil (hereinafter referred to as “aluminum sheet material”), conventional roll casting machines used to manufacture such aluminum sheet material typically have a twin-roll arrangement. In the twin-roll arrangement, a pair of substantially parallel, water-cooled, and counter-rotating rolls is used to cast the aluminum sheet material. Generally, after a given period of use, the surface, or roll shell, of these “caster” rolls must be reground and/or repaired because of heat cracks resulting from thermal fatigue and/or out-of-roundness (i.e., eccentricity) due to slipping between the roll core and roll shell. As the roll shell becomes thinner from regrinding, the roll shell surrounding the roll core must be replaced periodically and the roll core repaired before the twin-roll assembly is rebuilt.

It is generally known that the major cause of damage to prior art caster rolls is slipping between the roll core and the roll shell. The roll core in prior art caster rolls typically has circumferential grooves or channels formed in the surface of the roll core. The slipping typically occurs between the grooved or channeled surface of the roll core and the roll shell, which results in the formation of roll gaps between the roll core and roll shell. This leads to the aforementioned out-of-roundness (i.e., eccentricity) problem, which may ultimately result in misshaping the cast aluminum sheet material. Another problem associated with current caster rolls includes cracking in the roll shell due to thermal gradient and accompanying leakage of coolant onto the roll shell, which is a safety concern. Additionally, the thermal gradient along the surface of the roll core and roll core/roll shell slippage often cause the caster roll to distort or bend, which also may result in misshaping the cast aluminum sheet material during production runs.

One approach known in the art for extending the service life of caster rolls is disclosed in U.S. Pat. No. 5,598,633 to Hartz. In the Hartz '633 patent, the surface of the roll core is covered with two overlays of stainless steel each having a distinct hardness. The overlay of stainless steel directly in contact with the surface of the roll core is softer than the second, external overlay of stainless steel. An analogous approach to the foregoing is disclosed in U.S. Pat. No. 5,265,332 also to Hartz. The Hartz '332 patent attempts to extend the service life of the roll core by coating the inner surface of the roll shell with hard chromium.

Internally cooled rolls are well known in the field of continuous sheet casting machines. For example, U.S. Pat. No. 5,279,535 to Hawes et al. discloses an internally cooled caster roll for use in continuous sheet casting applications that includes a plurality of longitudinally extending coolant-conveying bores that extend the length of the caster roll. An annular manifold in the form of an end cap is secured within a recess formed in each end face of the caster roll and defines a plurality of discreet pathways, which places the open ends of the longitudinally extending bores in fluid communication with one another. The end caps additionally define a pathway formed to place the open end of one bore in fluid communication with a coolant inlet or coolant outlet passageway of the caster roll. A similar cooling roll having longitudinally extending cooling channels is disclosed in published International Application No. PCT/EP01/09818 (WO 02/26425).

U.S. Pat. No. 5,209,283 to Miltzow et al. discloses a caster roll comprising a roll core with a plurality of threads and a threaded sleeve, which threads onto the threaded roll core. The threaded connection between the roll core and roll sleeve defines a spiral channel through which a cooling medium flows to cool the caster roll. A similar “threaded” roll core is disclosed in U.S. Pat. No. 5,292,298 to Scannell.

U.S. Pat. No. 4,944,342 to Lauener discloses a continuous caster roll for casting aluminum sheet material. The caster roll is comprised of a roll shell enclosing a roll core. Cooling medium flows through axial cooling channels defined in the outer surface of the roll core. A counter flow principle is applied in the caster roll in which the cooling medium alternately flows in the cooling channels from one end of the caster roll to the other.

Further, U.S. Pat. No. 4,773,468 also to Lauener, discloses a method for extending the service life of a caster roll. In the caster roll disclosed by the Launer '468 patent, a plurality of rods is placed axially in grooves formed in the roll core of the caster roll. The rods protrude radially outward from the roll core and a roll shell is shrink-fitted onto the rods. As the roll is used in production runs, the roll shell wears and once the wear has proceeded to a predefined lower limit, the rods are replaced and a new roll shell is shrink-fitted onto the rods. Other references in the field of internally cooled caster rolls include U.S. Pat. No.: 5,887,644 to Akiyoshi et al.; U.S. Pat. Nos. 2,850,776; 2,790,216; and 2,664,607 all to Hunter. The disclosure of each of the references identified hereinabove is incorporated into this disclosure by reference.

The foregoing references disclose various prior art arrangements and methods for manufacturing, internally cooling, and generally extending the service of caster rolls. Nonetheless, a need still exists for a reduced cost, internally cooled caster roll having an extended service life between roll shell replacements. Additionally, a need exists for a roll shell replacement method that reduces the costs associated with roll shell replacements generally, which is the primary capital outlay required to extend the service life of caster rolls.

SUMMARY OF THE INVENTION

The present invention is a caster roll used in the manufacturing of metal plate, strip, sheet, or foil. In one embodiment, the caster roll comprises a cylindrical roll core and at least one metal overlay formed on the roll core. The roll core has a central longitudinal axis and defines a plurality of longitudinally extending cooling passages for conducting a cooling medium through the roll core to cool the roll during use. The cooling passages may be located proximate to the surface of the roll core and may be spaced regularly about the central longitudinal axis of the roll core. The roll core may comprise a cylindrical roll body and two outward extending axles. The at least one metal overlay may be formed on the roll body. The cooling passages may extend substantially the entire length of the roll body, and may be spaced regularly about the central axis of the roll body.

The roll core may comprise at least one centrally located inlet passage and a plurality of radially extending passages extending from the at least one inlet passage to the cooling passages for conducting the cooling medium from the at least one inlet passage to the cooling passages. The at least one inlet passage may extend substantially parallel to the central longitudinal axis of the roll core and the radial passages may extend substantially perpendicular to the at least one inlet passage. Alternatively, the radial passages may each define an acute angle with the central longitudinal axis.

The roll core may further comprise at least one centrally located inlet passage and one centrally located outlet passage and a first and second plurality of radially extending passages. The first plurality of radially extending passages may extend from the at least one inlet passage to the cooling passages for conducting the cooling medium to the cooling passages and the second plurality of radially extending passages may extend from the cooling passages to the at least one outlet passage for conducting the cooling medium from the cooling passages to the at least one outlet passage. The at least one inlet passage and at least one outlet passage may extend substantially parallel to the central longitudinal axis of the roll core and the first and second plurality of radial passages may extend substantially perpendicular to the at least one inlet passage and at least one outlet passage. Alternatively, the first and second plurality of radial passages may each define an acute angle with the central longitudinal axis.

The at least one inlet passage and at least one outlet passage may extend from one of the axles of the roll core, through the roll body, and at least partially through the second axle. The cooling passages may extend the entire length of the roll body and end caps may be attached, respectively, to opposite ends of the roll body for closing the ends of the cooling passages.

In another embodiment, the roll generally comprises a cylindrical roll core having a central longitudinal axis and a metal overlay formed on the roll core. The metal overlay defines a plurality of cooling passages for conducting a cooling medium through the metal overlay to cool the roll during use. The cooling passages may extend substantially parallel to the central longitudinal axis of the roll core and longitudinally in the metal overlay, preferably substantially the entire length of the metal overlay. The cooling passages may be spaced regularly about the central longitudinal axis of the roll core.

The roll core may comprise a cylindrical roll body and two outward extending axles and the metal overlay may be formed on the roll body. The cooling passages may extend substantially the entire length of the roll body in the metal overlay. End caps may be attached, respectively, to opposite ends of the roll body for closing the ends of the cooling passages in the metal overlay.

In still another embodiment, the roll is generally comprised of a cylindrical roll core having a central longitudinal axis, a first metal overlay formed on the roll core, and at least one additional metal overlay formed on the first metal overlay. The first metal overlay preferably defines a plurality of cooling passages for conducting a cooling medium through the first metal overlay to cool the roll during use. Preferably, the first metal overlay has a hardness lower than the hardness of the at least one additional metal overlay. The cooling passages may extend substantially parallel to the central longitudinal axis of the roll core and substantially the entire length of the first metal overlay. The cooling passages may be spaced regularly about the central longitudinal axis of the roll core.

The roll may comprise a cylindrical roll body and two outward extending axles. The first metal overlay and the at least one additional metal overlay may be formed on the roll body. The cooling passages may extend substantially the entire length of the roll body and be spaced regularly about the central longitudinal axis of the roll core. End caps may be attached, respectively, to opposite ends of the roll body for closing the ends of the cooling passages in the first metal overlay.

The first metal overlay and the at least one additional metal overlay may each be formed to a thickness of less than about 6 inches and, preferably, between about 0.010 to 6 inches. The first metal overlay may be a thermally conductive metal, such as copper, bronze, steel, and the like. The at least one additional metal overlay may be a metal alloy, such as a nickel, cobalt, copper, or titanium based alloy. The at least one additional metal overlay may also be steel. The at least one additional metal overlay may be a single metal overlay formed on the first metal overlay and be comprised of any of the metals identified hereinabove.

The present invention is also a method of manufacturing a roll adapted for use in manufacturing metal plate, strip, sheet, or foil. The method may generally include the steps of: providing a cylindrical roll core having a central longitudinal axis; forming a plurality of longitudinally extending cooling passages in the roll core proximate to the surface of the roll core for conducting a cooling medium through the roll core to cool the roll during use; and forming at least one metal overlay on the roll core. The at least one metal overlay may be formed on the roll core by any one of the following processes or like processes: submerged arc welding, spray forming, thermal spraying, hot isostatic pressing, pack diffusion, vapor deposition, and electrolytic plating.

The cooling passages may be formed to be spaced regularly about the central longitudinal axis of the roll core. The step of forming the longitudinally extending cooling passages may comprise drilling holes in the roll core extending substantially parallel to the central longitudinal axis of the roll core. The roll core may have a roll body. The step of forming the longitudinally extending cooling passages may comprise drilling holes in the roll body extending substantially parallel to the central longitudinal axis of the roll core and the entire length of the roll body. The method may comprise the additional step of attaching end caps to opposite ends of the roll body to close the ends of the cooling passages. The method may further comprise the step of heat treating the roll to a temperature of between about 400° F. to 1500° F. for between about 1 to 48 hours after forming the at least one metal overlay on the roll core, particularly when the at least one metal overlay comprises steel.

The roll core may define at least one centrally located and longitudinally extending inlet passage. The method may further comprise the steps of: forming a plurality of radially extending passages in the roll core to connect the cooling passages to the at least one inlet passage; and plugging the radial passages at the surface of the roll core prior to the step of forming the at least one metal overlay on the roll core. The step of forming the radially extending cooling passages in the roll core may comprise drilling holes in the roll core extending substantially perpendicular to the central longitudinal axis of the roll core to connect the cooling passages to the at least one inlet passage. Alternatively, the step of forming the radially extending cooling passages in the roll core may comprise drilling holes in the roll core at an acute angle with respect to the central longitudinal axis of the roll core to connect the cooling passages to the at least one inlet passage.

The roll core may further define at least one centrally located and longitudinally extending outlet passage. The method may further comprise the steps of: forming a plurality. of radially extending passages in the roll core to connect the cooling passages to the at least one inlet passage and the at least one outlet passage; and plugging the radial passages at the, surface of the roll core prior to the step of forming the at least one metal overlay on the roll core. The radially extending cooling passages may be drilled in the roll core to extend substantially perpendicular to the central longitudinal axis of the roll core or at an acute angle with respect to the central longitudinal axis of the roll core to connect the cooling passages to the at least one inlet passage and at least one outlet passage.

In another embodiment, the method of manufacturing the roll generally comprises the steps of: providing a cylindrical roll core having a central longitudinal axis; forming a metal overlay on the roll core; and forming a plurality of longitudinally extending cooling passages in the metal overlay for conducting a cooling medium through the metal overlay to cool the roll during use. The metal overlay may be formed on the roll core by any of the processes indicated previously.

The cooling passages may be formed in the metal overlay to be spaced regularly about the central longitudinal axis of the roll core. The step of forming the longitudinally extending cooling passages may comprise drilling holes in the metal overlay extending substantially parallel to the central longitudinal axis of the roll core. The holes may be drilled in the metal overlay to extend substantially the entire length of the roll body. End caps may be attached to opposite ends of the roll body to close the ends of the cooling passages in the metal overlay. The roll may be heat treated to a temperature of between about 400° F. to 1500° F. for between about 1 to 48 hours after forming the metal overlay on the roll core, particularly when the metal overlay comprises steel.

The roll core may define at least one centrally located and longitudinally extending inlet passage. The method may further comprise the steps of: forming a plurality of radially extending passages in the metal overlay and roll core to connect the cooling passages to the at least one inlet passage; and plugging the radial passages at the surface of the metal overlay. The step of forming the radially extending cooling passages in the roll core may comprise drilling holes in the metal overlay and roll core extending substantially perpendicular to the central longitudinal axis of the roll core or at an acute angle with respect to the central longitudinal axis to connect the cooling passages to the at least one inlet passage.

The roll core may further define at least one centrally located and longitudinally extending outlet passage, and the method may further comprise the steps of: forming a plurality of radially extending passages in the metal overlay and roll core to connect the cooling passages to the at least one inlet passage and the at least one outlet passage; and plugging the radial passages at the surface of the metal overlay.

In another embodiment of the method of manufacturing the roll of the present invention, the method generally includes the steps of: providing a cylindrical roll core having a central longitudinal axis; forming a first metal overlay on the roll core; forming a plurality of longitudinally extending cooling passages in the first metal overlay for conducting a cooling medium through the first metal overlay to cool the roll during use; and forming at least one additional metal overlay on the first metal overlay. The first metal overlay and the at least one additional metal overlay may be formed on the roll core by any of the processes indicated previously. The cooling passages are preferably formed in the first metal overlay to be spaced regularly about the central longitudinal axis of the roll core. The step of forming the longitudinally extending cooling passages may comprise drilling holes in the first metal overlay extending substantially parallel to the central longitudinal axis of the roll core. End caps may be attached, respectively, to opposite ends of the roll body to close the ends of the cooling passages in the first metal overlay. The roll may be heat treated to a temperature of between about 400° F. to 1500° F. for between about 1 to 48 hours after forming the at least one additional metal overlay on the first metal overlay, particularly when the first metal overlay and/or the at least one additional metal overlay comprises steel.

The roll core may define at least one centrally located and longitudinally extending inlet passage and at least one centrally located and longitudinally extending outlet passages. The method may further comprise the steps of: forming a plurality of radially extending passages in the first metal overlay and roll core to connect the cooling passages to the at least one inlet passage; and plugging the radial passages at the surface of the first metal overlay prior to the step of forming the at least one additional metal overlay on the first metal overlay. The step of forming the radially extending cooling passages in the roll core may comprises drilling holes in the first metal overlay and roll core extending substantially perpendicular to the central longitudinal axis of the roll core or at an acute angle with respect to the central longitudinal axis of the roll core to connect the cooling passages to the at least one inlet passage.

The method also comprises the steps of: forming a plurality of radially extending outlet passages in the first metal overlay and roll core to connect the cooling passages to the at least one inlet passage and the at least one outlet passage; and plugging the radial passages at the surface of the first metal overlay prior to the step of forming the at least one additional metal overlay on the first metal overlay. The step of forming the radially extending cooling passages in the roll core may comprise drilling holes in the first metal overlay and roll core extending substantially perpendicular to the central longitudinal axis of the roll core or at an acute angle with respect to the central longitudinal axis of the roll core to connect the cooling passages to the at least one inlet passage and at least one outlet passage.

Additionally, the method of the present invention relates to resurfacing existing rolls, which may be adapted for use in manufacturing metal plate, strip, sheet, or foil. The resurfacing method generally comprises the steps of: providing an existing roll having a central longitudinal axis and a roll core comprising a work surface defining grooves or channels; removing the existing work surface from the roll core to form a substantially smooth surface; forming a first metal overlay on the substantially smooth surface of the roll core; forming a plurality of longitudinally extending cooling passages in the first metal overlay; and forming at least one additional metal overlay on the first metal overlay.

The resurfacing method may further comprise the step of connecting the cooling passages to existing cooling conduits in the roll core. The first metal overlay and the at least one additional metal overlay may be formed on the roll core by any of the processes indicated previously.

Further details and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the drawings, wherein like parts are designated with like reference numerals throughout.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 1-10, a caster roll10in accordance with the present invention is shown. The caster roll10is generally comprised of a roll core12and one or more metal overlays formed on the roll core12. The roll core12is preferably solid as shown in the various accompanying figures, but may also be hollow (i.e., annular-shaped). In the embodiment of the caster roll10illustrated inFIGS. 1-10, two metal overlays are formed on the roll core12. The two metal overlays are separately designated with reference numerals “14” and “16”, respectively, throughout this disclosure. Accordingly, the caster roll10will be described hereinafter in terms of two metal overlays, including a first metal overlay14formed directly on the roll core12and a second metal overlay16formed on top of the first metal overlay14. However, other embodiments described in this disclosure comprise only one metal overlay on the roll core12. Additionally, the present invention is intended to encompass the use of three (3) or more metal overlays formed on the roll core12.

The roll core12has a generally cylindrical construction and comprises a cylindrical center section or roll body18and two outward extending axles20,22. The first and second metal overlays14,16are formed on top of the roll body18, as discussed hereinafter. The roll body18forms the portion of the caster roll10that contacts or casts metal when the caster roll10is used in connection with continuous sheet casting machines (not shown). The caster roll10is intended for use with metal that may be in solid, semi-solid, or liquid form. One of the axles20,22is preferably configured to be driven by the casting machine. Either axle20,22may be configured as the “drive end” axle of the caster roll10. For convenience in explaining the present invention, axle “20” will be referred to hereinafter as the “drive end axle20” or “first axle20”. The other axle22is configured to admit a cooling medium into the roll core12and discharge the same in the manner discussed hereinafter and will be referred to as the “cooling end axle22” or “second axle22”. A preferred cooling medium for the caster roll10is water. Cooling mediums other than water, such as oil or glycol, may be used in the caster roll10, however water is preferred. The cooling medium may be a mixture of cooling mediums and chemical additives added to the cooling medium for preventing corrosion. The roll core12may be formed of 4340 Steel (i.e., low carbon steel) and substantially equivalent metals and materials. The cooling medium is referred to as cooling water hereinafter, but any of the cooling mediums (and mixtures) set forth hereinabove may be used in place of “cooling water” in the following discussion.

The roll core12defines one or more centrally located passages24that extend substantially through the roll core12. The central passages24may also extend entirely through the roll core12. In the caster roll10shown inFIGS. 1-10, the roll core12defines four (4) centrally located and longitudinally extending passages24for carrying water through the roll core12. Additional or fewer central passages24may be used in the roll core12in accordance with the present invention, but the caster roll10will be described in this disclosure in terms of four (4) exemplary central passages24. At a minimum, one (1) inlet or supply central passage24and one (1) outlet or return central passage24, which are in fluid communication with each other, is all that is required for supplying cooling water to the roll core12and discharging the same in accordance with the present invention.

As indicated, the central passages24provide inlet (i.e., supply) and outlet (i.e., return) conduits for carrying water into and out of the roll core12. In particular, the central passages24are generally divided into two cooling water inlet passages26and two cooling water outlet passages28. The inlet and outlet passages26,28are interconnected, respectively, and form two separate cooling water flow circuits in the roll core12, which are identified herein with additional reference characters “a” and “b” for clarity. Accordingly, one of the inlet passages26ais connected to one of the outlet passages28ato form a first flow circuit, and the second inlet passage26bis connected to the second outlet passage28bto form a second flow circuit within the roll core12. The cooling water “flow circuits” to be described hereinafter are an exemplary arrangement for cooling the roll core12and caster roll10of the present invention and may be replaced by any equivalent fluid flow arrangement, which is within the skill of one skilled in the art.

The openings to the inlet passages26a,26band outlet passages28a,28bare located at the cooling end axle or second axle22. The inlet passages26a,26band outlet passages28a,28bpreferably extend from the cooling end axle22through the roll body18and partially through the drive end axle20. The inlet passages26a,26band outlet passages28a,28bare preferably connected together, respectively, in both the drive end axle20and the cooling end axle22. Alternatively, the inlet passages26a,26band outlet passages28a,28bmay be connected together, respectively, in either the drive end axle20or the cooling end axle22. The inlet passages26a,26bcarry cooling water from the cooling end axle22through the roll body18and into the drive end axle20, and the outlet passages28a,28bthen return the now heated water back to the cooling end axle22, as described further herein.

The roll body18of the roll core12further defines a plurality of radially extending passages30that extend outward from the inlet passages26a,26band outlet passages28a,28bto a surface31of the roll body18. The radial passages30are generally in fluid communication with passages formed in the first metal overlay14, as discussed herein. The inlet passages26a,26bare each preferably connected to four (4) radial passages30, and the outlet passages28a,28bare each preferably connected to four (4) radial passages30. However, additional or fewer radial passages30may be connected to the inlet passages26a,26band outlet passages28a,28b. The choice of four (4) radial passages30connected to the inlet passages26a,26band four (4) radial passages30connected to the outlet passages28a,28bis provided as an example to describe the caster roll10. At a minimum, only one (1) radial passage30is required for each of the inlet passages26a,26band outlet passages28a,28b. In the preferred embodiment, the radial passages30are formed into the roll body18after the first metal overlay14is applied to the roll body18, as discussed hereinafter. Alternatively, the radial passages30may be formed in the roll body18prior to forming the first metal overlay16.

The radial passages30are preferably symmetrically distributed around the circumference of the roll body18and in fluid communication with longitudinal passages that may be formed in the first metal overlay14, as discussed further hereinafter. The radial passages30defined in the roll body18of the roll core12are provided to conduct cooling water to these “longitudinal passages” and then return heated water to the central passages24. In general, cooling water is conducted through inlet passages26a,26b, outward in the roll body18through the radial passages30. Heated water is returned through the radial passages30to the outlet passages28a,28b. The outlet passages28a,28bthen conduct the heated water out of the roll core12. The radial passages30are preferably provided at both ends of the roll body18(i.e., proximate to the ends of the roll body18), but may also be located at only one end of the roll body18.

The inlet passages26a,26bconduct cooling water into the roll core12and, for this purpose, are preferably in fluid communication with an external source of cooling water (not shown) such as an evaporative cooling system (i.e., cooling tower). The outlet passages28a,28breturn heated water to the cooling water source, or other location. The radial passages30enable cooling water to be conducted from the inlet passages26a,26bto the first metal overlay14and returned to the outlet passages28a,28b.

Referring toFIGS. 1-13, the surface31of the roll body18is preferably free of grooves and channels, such as those that are generally found in prior art caster rolls. The first metal overlay14is formed on top of the relatively smooth surface31(i.e., free of grooves and channels) of the roll body18. The second metal overlay16is formed on top of a surface32of the first metal overlay14. Preferably, the first and second metal overlays14,16are formed on the roll body18by a metal deposition process, such as: submerged arc welding, spray forming, thermal spraying, hot isostatic pressing, pack diffusion, vapor deposition, electrolytic plating and the like.

The caster roll10according the present invention is provided with a plurality of enclosed cooling medium conduits or passages34that extend longitudinally in the caster roll10for cooling the caster roll10during use. In the presently preferred embodiment of the caster roll10, the cooling passages34are formed in the first metal overlay14. In another embodiment of the caster roll10, the cooling passages34are formed in the roll core12. The cooling passages34are placed in fluid communication with the inlet passages26a,26band outlet passages28a,28bpreferably by forming (i.e., drilling) the radial passages30into the roll core12after the first metal overlay14is formed on the roll core12and the cooling passages34are formed (i.e., by drilling longitudinally) in the first metal overlay14. The embodiment of the caster roll10wherein the cooling passages34are provided in the first metal overlay14will be discussed next in this disclosure. The embodiment of the caster roll10wherein the cooling passages34are provided in the roll core12is discussed in connection withFIG. 16later in this disclosure. The caster roll10illustrated inFIG. 16is formed in a similar manner to the caster roll10shown, for example, inFIG. 2, wherein the cooling passages34are first formed by drilling longitudinally extending holes or apertures in the roll body18and then drilling the radial passages30to connect the cooling passages34to the inlet passages26a,26band outlet passages28a,28b.

The cooling passages34preferably extend substantially parallel to a central longitudinal axis L of the roll core12and radially outward from the central longitudinal axis L. The cooling passages34further preferably extend the entire length of the first metal overlay14and the roll body18and are spaced regularly about the circumference of the roll body18. As indicated previously, the cooling passages34may be formed by drilling longitudinal holes the length of the first metal overlay14. Additionally, as indicated previously, the radial conduits30may be formed by drilling radially into the first metal overlay14and roll core12to connect the cooling passages34to the central passages24(i.e., the inlet passages26a,26band outlet passages28a,28b). In practice, the cooling passages34are only required to extend substantially the distance between the openings of the radial passages30to connect the cooling passages34to the inlet passages26a,26band outlet passages28a,28b. Consequently, the cooling passages34are not necessarily limited to extending the entire length of the first metal overlay14.

The first metal overlay14is preferably made of a metal or metal alloy exhibiting good thermal conductivity properties such as copper, bronze, steel, stainless steel, and the like. The second metal overlay16is preferably a metal that is resistant to thermal fatigue cracking wear. A suitable metal for the second metal overlay16will have a hardness range in the range of 30 to 66 Rockwell C, preferably 55 to 60 Rockwell C. An exemplary list of metals for the second metal overlay16includes: steel and nickel, cobalt, copper, and titanium based alloys.

The cooling passages34are preferably formed so that adjacent pairs of cooling passages34are interconnected at one of the ends of the roll body18of the roll core12. Thus, the adjacent pairs of cooling passages34form cooling flow paths or conduits comprised of one “inlet” or “supply” cooling passage34, which is connected to a radial passage30that is in turn connected to one of the inlet passages26a,26b, and one “outlet” or “return” cooling passage34, which is connected to a radial passage30that is in turn connected to one of the outlet passages28a,28b. Accordingly, the cooling passages34, radial passages30, and inlet and outlet passages26,28are all in fluid communication and define an internal cooling medium flow system within the caster roll10that distributes cooling water from an external source to the interior of the roll core12and roll body18through the inlet passages26a,26b, then outward in the roll body18through the radial passages30, and finally to the interior of the first metal overlay14through the cooling passages34. An analogous return path to the external source of cooling water is also provided by the above-described flow system, as will be appreciated by one skilled in the art. The cooling passages34are not required to be interconnected, and may be provided as single cooling passages34.

As indicated previously, an additional metal overlay such as the second metal overlay16and, possibly, multiple metal overlays or coatings may be formed on top of the first metal overlay14. The second metal overlay16is formed on the surface32of the first metal overlay14preferably by any one of the metal deposition processes or techniques identified previously. For example, the second metal overlay16may be provided as a thin, hard coating of metal such as tungsten, carbide, or chromium, which is applied to the surface32of the first metal overlay14by a vapor deposition technique, an electrolytic plating technique (i.e., for chromium), or by one of the techniques identified previously.

End caps36(also shown inFIGS. 14 and 15) are provided at opposite ends38,40(i.e., first and second ends38,40, respectively) of the roll body18of the roll core12to seal the open ends of the cooling passages34and to interconnect the “inlet” and “outlet” cooling passages34as necessary. The end caps36are annular shaped (as shown inFIG. 14) to fit over the respective axles20,22and may be sealed to the first and second ends38,40of the roll body18by conventional O-rings (not shown) and mechanical fasteners42. The end caps36close the open ends of the cooling passages34to close the cooling medium flow system.

With continued reference toFIGS. 1-13, a method of manufacturing the caster roll10wherein the cooling passages34are provided in the first metal overlay14will now be discussed. As indicated previously, the surface31of the roll body18is preferably provided free of external channels or grooves and preferably has a surface roughness suitable for depositing the first metal overlay14onto the surface31of the roll body18by any of the processes identified previously.FIG. 5shows the roll core12and roll body18prior to forming (i.e., depositing) the first metal overlay14onto the surface31of the roll body18. It should be noted that the radial passages30are not yet formed in the roll core12.FIG. 11shows the first metal overlay14after being deposited or applied onto the surface31of the roll body18and after the radial passages30are formed in the roll core12to connect the cooling passages34to the central passages (i.e., inlet passages26a,26band outlet passages28a,28b).

Once the first metal overlay14is formed on the surface31of the roll body18, the cooling passages34may be formed in the first metal overlay14. This is accomplished by drilling longitudinally extending holes in the first metal overlay14, which form the cooling passages34. The cooling passages34are preferably formed at regular angular intervals around the roll body18. The cooling passages34are spaced radially outward from the central passages24(i.e., inlet and outlet passages26,28) and the central longitudinal axis L.

Once the longitudinally extending cooling passages34are formed in the first metal overlay14, the cooling passages34may be formed in the roll core12to place the cooling passages34in fluid communication with the central passages24(i.e., inlet and outlet passages26,28) in the roll core12. The cooling passages34are formed by drilling radially into the first metal overlay14and roll core12at the desired pre-selected angular locations where the radial passages30are to be located in the roll core12. The drilling process forms radial holes44in the first metal overlay14that must be plugged before the second metal overlay16is formed on the first metal overlay14. The radial holes44are plugged by a plurality of plugs46, as shown inFIGS. 2 and 11. The plugs46are preferably made of the same type of metal as the first metal overlay14.

As discussed previously, any number of longitudinally extending cooling passages34may be provided in the first metal overlay14, which may be placed in fluid communication with any number of radial passages30formed in the roll core12. The cooling passages34are intended to conduct cooling water through the first metal overlay14, preferably the length of the first metal overlay14, and return heated water to the radial passages30in fluid communication with the outlet passages28a,28b.

Once the longitudinally extending cooling passages34and radial passages30are formed in the first metal overlay14and roll body18of the roll core12, the second metal overlay16is preferably formed directly on top of the first metal overlay14. The second metal overlay16may be applied by any of the metal deposition or forming processes indicated previously. The second metal overlay16is preferably made of any of the hard metals identified previously. The second metal overlay16will generally have a hardness higher than the hardness of the first metal overlay14. Preferably, the first and second metal overlays14,16each have a thickness of about 0.010 to 6 inches. The second metal overlay16generally forms the “work surface” of the caster roll10.

The caster roll10may be subjected to further treatment steps once the second metal overlay16is formed on the first metal overlay14. For example, the caster roll10may be heat treated to a temperature of between about 400° F. to about 1500° F. for a time period of about 1 to 48 hours to produce a hardness in the range of about 30 to 66 Rockwell C, as indicated previously, in the first and second metal overlays14,16, particularly when the first and second metal overlays14,16comprise steel. Additionally, a surface50of the second metal overlay16(i.e., the preferred work surface of the caster roll10) may be roughened such that the surface50of the second metal overlay16has a surface roughness suitable for manufacturing commercial aluminum plate, strip, sheet, or foil. The plugs46are preferably formed flush with the surface32of the first metal overlay14, or recessed into the first metal overlay14before the second metal overlay16is formed on the first metal overlay14. The deposition or formation of the second metal overlay16onto the first metal overlay14will fill any recesses defined in the first metal overlay14in the vicinity of the plugs46.

In an alternative embodiment of the caster roll10, the second metal overlay16may be omitted from the caster roll10, such as illustrated in FIG.11. The surface32of the first metal overlay14will now form the “work surface” of the caster roll10. Accordingly, the first metal overlay14in this embodiment is preferably formed of a hard metal, such as the metals identified previously in connection with the second metal overlay16. The metal plugs46are used to seal the radial holes44formed in the first metal overlay14. The plugs46are preferably formed flush with the surface32of the first metal overlay14. The true “work surface” area for this alternative embodiment of the caster roll10is generally the surface32of the first metal overlay14lying between the plugs46. The previously discussed heat treatment and surface roughening steps may be also be applied to the caster roll10having only the first metal overlay14as the “work surface” of the caster roll10.

Additionally, as shown in dotted lines inFIGS. 2 and 11, the radial passages30may be formed at an angle with respect to the central longitudinal axis L of the roll core12and the central passages24(i.e., inlet and outlet passages26,28). This eliminates the need for the plugs46because the radial passages30are formed in the ends38,40of the roll body18. The end caps36are used to seal the open ends of the cooling passages34, as described previously, and may be further used to seal the open ends of the “angled” radial passages30. The use of the “angled” radial passages30allows the entire surface32of the first metal overlay14to be used as the “work surface” of the caster roll10, in the embodiment of the caster roll10wherein only the first metal overlay14is applied to the roll core12. The “angled” radial passages30may also be applied to the presently preferred embodiment of the caster roll10having two or more metal overlays (i.e., the first and second metal overlays14,16). A suitable angle for the “angled” radial passages30is an acute angle, preferably an acute angle in the range of about 75° or less.

The methods described hereinabove for applying the first and second metal overlays14,16, as well. as additional metal overlays (if any), to the roll body12may also be applied to existing caster rolls. Specifically, the first and second metal overlays14,16may be applied to, for example, existing caster rolls having circumferential grooves or channels that define water passages for cooling the caster roll. A typical example of such a “grooved” or “channeled” caster roll is disclosed in U.S. Pat. No. 5,292,298 to Scannell, discussed previously.

The first and second metal overlays14,16may be applied, for example, to the caster roll disclosed by the Scannell patent by removing the roll shell from the roll core and, further, the machined circumferential grooves or channels (i.e., spiral ribs) formed on the roll core. The resulting roll core preferably has a substantially smooth surface, which generally means that the roll core is free of the original machined grooves or channels (i.e., spiral ribs). The first metal overlay14may then be applied as described previously. The longitudinally extending cooling passages34may be formed in the first metal overlay14in the manner discussed previously. Thereafter, the cooling passages34may be placed in fluid communication with existing radial and axial bores, channels, or conduits defined in the roll core of the existing caster roll, such as the heat transfer roll disclosed by the Scannell patent. The plugs46may be used to seal the radial holes44formed in the first metal overlay14. Finally, the second metal overlay16and possibly additional metal overlays may be formed on the first metal overlay14in the manner described previously. The process described previously for forming the caster roll10having only one metal overlay (i.e., the first metal overlay14) may also be used to “resurface” the existing caster roll, such as the heat transfer roll disclosed by the Scannell patent. The disclosure of the Scannell patent is relied upon only to illustrate the application of the processes discussed previously for forming the caster roll10of the present invention to existing caster rolls. The foregoing “retro-fitting” or “resurfacing” process is believed to be applicable to any internally cooled caster roll used in the continuous sheet casting field and this disclosure should not be interpreted as being applicable only to the specific arrangement of the caster roll disclosed by the Scannell patent.

Referring toFIG. 16, another embodiment of the caster roll10in accordance with the present invention is shown. InFIG. 16, the cooling passages34are now formed within the roll body18instead of the first metal overlay14. Accordingly, the entire fluid flow path for the cooling water is located within the roll core12. The cooling passages34are in fluid communication with the radial passages30and the radial passages30are in fluid communication with the inlet and outlet passages26,28as discussed previously. The radial passages30may be “angled” in the manner discussed previously in connection withFIGS. 2 and 11.

In general, the embodiment of the caster roll10shown inFIG. 16is substantially similar to the embodiments of the caster roll10having discussed previously having one metal overlay (i.e., first metal overlay14) and two or more metal overlays (i.e., first and second metal overlays14,16), except that the cooling passages34are now formed within the roll body18instead of in the first metal overlay14. The cooling passages34and radial passages30are formed in the same manner as described previously, for example by drilling longitudinally into the roll body18to form the cooling passages34and radially into the roll body18to form the radial passages30. The caster roll10shown inFIG. 16may have one metal overlay (i.e., first metal overlay14) or two or more metal overlays (i.e., first and second metal overlays14,16) formed on the roll body18in accordance with the present invention. However, as will be appreciated by one skilled in the art, the plugs46in the embodiment of the caster roll10illustrated inFIG. 16will now be inserted into the radial passages30at the surface31of the roll body18. The first metal overlay14may then be formed onto the surface31of the roll body18and cover the plugs46. If desired, additional metal overlays, such as the second metal overlay16may then be applied to the first metal overlay14. The end caps36may be used to seal the cooling passages34at the ends38,40of the roll body18. The end caps36may be further used to seal the “angled” radial passages30when these are used in the caster roll10illustrated in FIG.16. Generally, only one metal overlay (i.e., first metal overlay14) will be necessary in the caster roll10ofFIG. 16, made of any of the materials identified previously in connection with the second metal overlay16(i.e., a hard metal).

The flow pattern of the cooling water within the caster roll10and associated method of cooling the caster roll10will generally be described hereinafter with reference toFIGS. 1-16and specifically with reference to the caster roll10having the first and second metal overlays14,16. The cooling water first enters the caster roll10through the inlet passages26a,26b. The cooling water flows through the roll core12through the inlet passages26a,26b, which extend at least partially through the drive end axle20. The cooling water then flows outward in the roll body18through the radial passages30in fluid communication with the inlet passages26a,26b(i.e., “supply” radial passages30). The cooling water then flows longitudinally the length of the first metal overlay14(or roll body18) through the “inlet” or “supply” cooling passages34. Once reaching the end of the respective inlet cooling passages34, the now heated water flows back the length of the first metal overlay14(or roll body18) through the respectively interconnected “outlet” or “return” cooling passages34, which are in fluid communication with the outlet passages28a,28bthrough the “return” radial passages30. In summary, the heated water flows back the length of the first metal overlay14(or roll body18) through the outlet cooling passages34and into the return radial passages30. The return radial passages30, as stated, are in fluid communication with the outlet passages28a,28bin the roll core12. The outlet passages28a,28bconduct the heated water out of the roll core12. The inlet passages26a,26bare preferably in fluid communication with a continuous source of cooling water to continuously provide cooling water to the caster roll10during its operation.

The radial passages30and cooling passages34are preferably arranged to provide a plurality of counter-flowing cooling water circuits in the first metal overlay14(or roll body18). Referring, in particular, toFIGS. 11-13, the radial passages30are preferably defined substantially at each of the ends38,40of the roll body18(i.e., proximate to the ends38,40of the roll body18). Thus, a plurality of the radial passages30(i.e., supply radial passages30) are in fluid communication with the inlet passage26aat, for example, the first end38of the roll body18, and an additional plurality of the radial passages30(i.e., supply radial passages30) are in fluid communication with the inlet passage26aat the second end40of the roll body18. As shown inFIGS. 12 and 13, cooling water will flow. outward to the first metal overlay14substantially at both ends38,40of the roll body18. A similar configuration to the foregoing exists for the second inlet passage26b.

As described previously, the cooling passages34are preferably arranged in pairs, with each pair including an “inlet” cooling passage34and an interconnected “outlet” cooling passage34that returns heated water to one of the radial passages30for removal from the caster roll10. Thus, the supply radial passages30at the first end38of the roll body18supply cooling water to respective inlet cooling passages34that carry cooling water from the first end38to the second end40of the roll body18of the roll core12. Heated water is returned to the starting point (first end38) through the respectively interconnected outlet cooling passages34. Similarly, the supply radial passages30at the second end40of the roll body18supply cooling water to respective inlet cooling passages34that carry cooling water from the second end40of the roll body18to the first end38(i.e., in the opposite direction). Again, heated water is returned the length of the first metal overlay14(or roll body18) through the respectively interconnected outlet cooling passages34. Heated water is conducted away from the first metal overlay14through the return radial passages30provided at both ends38,40of the roll body18. The return radial passages30are in fluid communication with the outlet passages28a,28b, which conduct the heated water from the caster roll10. As will be appreciated by those skilled in the art, the first metal overlay14and second metal overlay16formed thereon are cooled by counter-flowing cooling water flows, which flow the length of the first metal overlay14(or roll body18).FIGS. 14 and 15show the annular end cap36that seals or closes the open ends of the cooling passages34, whether provided in the first metal overlay14or roll body18. The end caps36may also be used to seal the ends of the “angled” radial passages30, as indicated previously.

The casting roll10and procedures for making the same described hereinabove result in a caster roll having reduced maintenance and repair costs. Additionally, the deposition of the first and second metal overlays14,16, for example by submerged arc welding, on the roll core12eliminates the roll shell/roll core slippage problem that is well known in the art. Further, the use of multiple metal overlays on the roll core12reduces the possibility of cooling water leaking onto the external surface of the caster roll10(i.e., surface50), which improves the safety of the caster roll10when in use. It is believed that the roll shell replacement costs associated with prior art caster rolls may be reduced significantly using the processes described hereinabove and that the eccentricity problem associated with prior art caster roll may be reduced by up to about half (i.e., 50%).

While preferred embodiments of the present invention were described hereinabove, obvious modifications and alterations of the present invention may be made without departing from the spirit and scope of the present invention. The scope of the present invention is defined in the appended claims and equivalents thereto.