Abstract:
A metal processing apparatus, comprising a pay-off reel for supporting and uncoiling a coil of metal, a roller-leveler apparatus adapted to receive a strip of sheet metal from the pay-off reel for conditioning the strip of steel, a recoiler for re-coiling the coil of metal, and whereby the apparatus generates enough tension on the strip of metal to improve flatness and remove coil breaks from the strip of metal as it advances through the roller-leveler.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is related to U.S. Provisional Patent Application No. 60/713,174 filed Aug. 31, 2005 from which priority is claimed, and is hereby incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
       [0002]     Not Applicable.  
       BACKGROUND OF THE INVENTION  
       [0003]     The present invention relates to flat rolled metal and sheet metal processing. More particularly, the present invention relates to a method and apparatus for removing coil breaks and leveling metal using a roller-leveling machine in combination with high tension on the metal to enhance conditioning of the metal with a conditioning apparatus.  
         [0004]     A wide range of goods contain components manufactured from processed sheet metal, such as aircraft, automobiles, file cabinets and household appliances, to name only a few. Typically, the sheet metal is purchased directly from steel mills or steel service centers. However, some applications require that the sheet metal first pass through intermediate processors (sometimes referred to as “toll” processors) to refine the sheet metal before an original equipment manufacturer receives it. In many applications, the flatness and surface condition of the sheet metal is important. Flatness of sheet metal is important for virtually all stamping and blanking operations, while good surface conditions are important in applications where the surfaces of the metal sheet will be painted.  
         [0005]     Sheet metal straight from the mill typically contains a layer of “scale” on its surfaces. Scale is a layer of iron oxide that forms on the surface of hot rolled carbon steel while the steel is cooled. The rate at which the product is cooled, and the total temperature drop affects the amount and composition of scale that forms on the surface. Iron has a complex oxide structure with FeO (“wustite”) mechanically bonded to the base metal substrate, followed by a layer of Fe 3 O 4  (“magnetite”) chemically bonded to the wustite, and then a layer of Fe 2 O 3  (“hematite”) chemically bonded to the magnetite and exposed to the air. Typically, scale is removed in a pickling process in which the steel sheet is run through a sulfuric acid bath. Then a coating of oil is applied to prevent the sheet from rusting.  
         [0006]     A number of common defects affect sheet metal flatness, including “coil set”, “edge wave”, “center buckle”, and “coil break”. “Coil set” occurs when sheet metal is rolled into coil form for convenient storage and transportation and the strip takes on a coiled shape, which commonly referred to as “coil set.” Coil set occurs because the sheet metal has been bent past its yield point. More specifically, when sheet metal is coiled, the metal near the inside surface of the curved sheet is compressed past its yield point, and the metal near the outside surface of the curved sheet is stretched past its yield point. “Edge wave” occurs if the edge portions of the sheet are longer than the center portion of the sheet, resulting in undulations along one or both of the edge portions of the sheet. “Center buckle” results if the center portion of the sheet is longer than one or both of the edge portions, which results in bulging or undulating of the central portion of the sheet. “Coil break” occurs when defects in the sheet metal cause it to kink as it uncoils from the “pay-off” reel. This results in creases or ridges appearing in sheets as parallel lines transverse to the direction of rolling and generally extending across the width of the sheet.  
         [0007]     Various methods exist for leveling sheet metal. For example, a conventional flattening device such as a stretcher-leveler or tension-leveler can correct coil-set, edge wave, and center buckle. A stretcher-leveler grips the sheet metal strip in segments and stretches each segment individually. As such it operates relatively slowly. A tension leveler uses trailing and leading bridle rollers over which the metal strip passes in a serpentine configuration. The leading rollers rotate slightly faster than the trailing rollers, and hence the sheet stretches between them. However, stretcher-levelers and tension-levelers can be cost-prohibitive. In addition, the only apparatus known to the inventors that is believed to remove coil breaks from sheet metal is a temper-mill. The large size and high cost of temper-mills make them cost-prohibitive and difficult to combine with other processing equipment.  
         [0008]     Once the sheet metal is leveled, it lends itself to a conditioning procedure to remove the scale without the need for pickling and oil coating. Basically, the procedure involves subjecting the leveled sheet metal to brushes that remove most of the scale, indeed, all but the wustite. With the sheet so conditioned, it readily accepts paint, yet does not require oil to prevent further oxidation. See U.S. Pat. Nos. 6,732,561; 6,814,815; and 6,205,830, hereby incorporated by reference.  
         [0009]     One can achieve a measure of flatness in a sheet metal strip at modest expense by passing the metal strip through a roller-leveler having a succession of rollers that cause the strip to undergo multiple undulations. While a conventional roller-leveler is a less costly flattening apparatus, it has been considered ineffective. Depending on the severity of the defects, the roller-leveler produces a reasonably flat metal sheet. However, sheet metal with moderate to severe defects cannot be sufficiently flattened. In addition, there still exists a neutral axis in the sheet metal where the yield point of the metal has not been exceeded by the small diameter rollers. Metal lying at or near this neutral axis may be in a stressed condition (and tend to spring back toward its original shape) because it has not been deformed past its elastic limit. Therefore, even after roller leveling, the material at or near the neutral axis will possess internal residual stresses, because the grain structure is not uniform. The roller-leveler does not consistently leave the sheet metal flat enough for conditioning with brushes.  
         [0010]     Thus, there is a need for a cost-effective sheet metal processing apparatus that removes coil breaks in a continuous strip of sheet metal, improves flatness, and conditions the sheet metal by removing scale.  
       SUMMARY OF THE INVENTION  
       [0011]     Briefly stated, the invention is a metal processing apparatus comprising a pay-off reel for supporting and uncoiling a coil of metal and a take-up reel for re-coiling the coil of metal and placing tension on a strip of metal between the pay-off reel and take-up reel. A roller-leveler apparatus is adapted to receive the strip of sheet metal from the pay-off reel, improves flatness, and remove coil breaks from the metal. A surface conditioning apparatus has at least one brush adapted for engagement with a surface of the strip of metal in a manner to remove scale from the surface.  
         [0012]     The foregoing and other features, and advantages of the invention as well as embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings.  
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0013]     In the accompanying drawings which form part of the specification:  
         [0014]      FIG. 1  is a elevation view of a sheet metal processing apparatus in accordance with and embodying the present invention;  
         [0015]      FIG. 2  is a side view of a leveler;  
         [0016]      FIG. 3A  is a side view of a first embodiment of a surface conditioner;  
         [0017]      FIG. 3B  is a exploded perspective view of a translating mechanism;  
         [0018]      FIG. 3C  is a side view of a second embodiment of the surface conditioner;  
         [0019]      FIG. 4  is a side view of a cleaning module;  
         [0020]      FIG. 5  is a plan view of the cleaning module;  
         [0021]      FIG. 6  is a side view of a modified cleaning module;  
         [0022]      FIG. 7  is a side view of a take-up reel;  
         [0023]      FIG. 8  is a enlarged perspective view of a mandrel of the take-up reel;  
         [0024]      FIG. 9  is an exploded view of the mandrel of the take-up reel of  FIG. 8 ; and  
         [0025]      FIG. 10  is a section view of the mandrel along section line  10 - 10  of  FIG. 8 . 
     
    
       [0026]     Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings.  
       DETAILED DESCRIPTION  
       [0027]     The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. Additionally, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.  
         [0028]     Referring now to the drawings, a sheet metal processing apparatus A conditions sheet metal that is supplied in a roll B, typically from a hot strip mill. As such, the sheet metal contains a scale on both of its surfaces, generally oxides of iron that take the form of wusite (FeO) bonded directly to the surface of the steel, magnetic (Fe 3 O 4 ) bonded to the wusite, and hematite (Fe 2 O 3 ) bonded to the magnetite. The scale renders the steel unsuitable for most products manufactured from sheet steel and is thus removed—indeed, in the processing apparatus A. Actually, as explained in U.S. Pat. No. 6,814,815, which is incorporated herein by reference, only the hematite and magnate need be removed to provide steel sheet suitable for conversion into panels and the like that are painted or otherwise used in manufactured items. It is believed that the wusite serves to protect the steel sheet from oxidation at its surfaces and thus should be retained. As such, it serves as a substitute for an oil which film is applied after the more traditional picketing which the apparatus A eliminates.  
         [0029]     Apart from the scale, the steel on the roll B may have defects that affect sheet metal flatness, such as edge waves, coil set, or center buckles, which exist in the roll B itself. But for processing in the apparatus A, the coiled steel sheet must be withdrawn from the roll B in the form of a strip S. As the strip S is withdrawn, it may acquire coil breaks.  
         [0030]     The preferred embodiment of apparatus A includes ( FIG. 1 ) a payoff reel  2  that holds the roll B, a crop shear  4  for cutting off the leading end of the strip S, a roller leveler  6  for flattening the strip S, a side trimmer  8  for trimming the sides of the strip S, a surface conditioner  10  where the actual scale is removed, at least down to the wusite, and finally a recoiler  12 . The foregoing components act upon the strip S in the order identified.  
         [0031]     The payoff reel  2  ( FIG. 1 ) can be any payoff reel known to those skilled in the art and, as such, the preferred embodiment includes a mandrel  18  that actually supports the roll B of sheet metal. As the sheet metal strip S pays off the roll B, the mandrel  18  rotates, but under the control of a brake  20  to impart a measure of tension to the strip S. Moreover, the reel  2  has a peeler  22  to deflect the strip S away from the roll B notwithstanding the coil set imparted to the sheet metal in the roll B.  
         [0032]     The crop shear  4  ( FIG. 1 ) likewise can be any crop shear known to those skilled in the art. In the preferred embodiment, it slices a short segment from the strip S at the leading edge of the strip S so as to eliminate imperfections from the leading edge and render the leading edge perpendicular to the side edges. This facilitates threading through the surface conditioner  10  and enables the recoiler  12  to firmly grip the end of the strip S to thereby apply a substantial tensile force to the strip S.  
         [0033]     The leveler  6  also can be any leveler known to those skilled in the art. In the preferred embodiment, it has ( FIG. 2 ) a frame  24  that supports upper and lower working rollers  26  and  28 , respectively, and backing rollers  30  behind the working rollers  26  and  28  to prevent the rollers  26  and  28  from deflecting. The rollers  26  and  28  extend transversely with respect to the strip S, each for at least the full width of the strip S. Moreover, the upper rollers  26  are offset horizontally with respect to the lower rollers  28  in the direction of advance for the strip S and are further offset vertically so that the lower surface areas of the upper rollers  26  extend below the upper surface areas  28  of the lower rollers  28 . The lower rollers  28  are supported on a carrier  32  that is in turn supported on the frame  24 . The carrier can be raised and lowered and inclined slightly to control the vertical offset between the upper and lower rollers  26  and  28  through the leveler  6 . Moreover, the amount of vertical offset is adjustable across the width of the rollers  26  and  28 . The backing rollers  30  lie behind the upper and lower working rollers  26  and  28  and retard deflection of the working rollers  26  and  28 . One such type of leveler is sold by Butech, Inc., located in Salem, Ohio, and Red Bud Industries, located in Red Bud, Ill.  
         [0034]     Initially, to thread the strip S through the leveler  6 , the rollers  26  and  28  are powered by an electric motor  36  which transmits its power to the rollers  26  and  28  through a gear box (not shown). Once the strip S is secured to the recoiler  12 , the strip S is pulled through the leveler  6  by the recoiler  12 . During operation, the linear velocity of the strip S is controlled by the recoiler  12 . The strip S passes between the upper and lower working rollers  26  and  28 , which assume an undulated configuration. Indeed, the undulations are such that they cause elastic and plastic deformation in the strip S. This serves to remove some of the coil set from the strip S and some of the edge wave and center buckle as well, assuming that there is some. In combination with the substantial tension applied to the strip S by the recoiler  12 , it also removes coil breaks.  
         [0035]     The surface conditioner  10  performs much more effectively when substantial tension is applied to the strip S by the recoiler  12 . As the recoiler  12  pulls the strip S, tension is developed through resistance primarily at the leveler  6 , but also at the payoff reel  2 . The additional tension causes additional elastic and plastic deformation, which enhances the temporary and permanent flatness in the strip S. As a result, the tension further levels the strip S for more effective removal of the scale by the surface conditioner  10 . Enough working rollers  26  and  28  exist with sufficient vertical offset to prevent the tension applied to the strip S from simply pulling the strip S through the leveler  6  with the strip S sliding over the surfaces of the rollers  26  and  28 . Very little, if any, slippage occurs between strip S and the upper and lower working rollers  26  and  28 .  
         [0036]     The side trimmer  8  ( FIG. 2 ) cuts off a small segment along the side of the strip S, thus eliminating imperfections in the side edges and leaving the strip S with clean side edges that are straight, parallel and cut to a specific width. The trimmer  8  likewise can be any trimmer known to those skilled in the art.  
         [0037]     The surface conditioner  10  removes at least some of the scale from both surfaces of the strip S while the strip S is maintained under substantial tension applied at the recoiler  12  and resisted primarily at the leveler  6 , but also at the payoff reel  2 . Preferably, the surface conditioner  10  removes the layers of hematite and magnetite, while leaving the layer of wusite bonded to the steel.  
         [0038]     The surface conditioner  10  includes ( FIG. 3 ) a fixed frame  38  and a subframe  40  that is supported within the fixed frame  38  on a pair of tracks  44 , so that it can translate to and fro in a direction transverse to the direction of advance of the strip S. To this end, the subframe  40  has wheels  46  that roll over the tracks  44 . The subframe  40  is coupled with a translating mechanism  48 , which moves in an oscillating motion back and forth over the track  44  with the midpoint of the movement coinciding with the centerline of the strip S. This oscillating motion promotes more uniform wear of several cleaning modules  60  ( FIG. 3 ), which are attached to the subframe  40  and described below in more detail. The range of movement is relative to the width of the strip S and should be great enough to allow the entire surface of the cleaning module  60  to be utilized. Its frequency should range between 1 and 3 cycles/min. and preferably 2 cycles/min.  
         [0039]     In the embodiment depicted in  FIGS. 3A and 3B , the translating mechanism  48  is a hydraulic cylinder  49  mounted between the track  44  and the wheel  46 . Position sensors (not shown) mounted on either side of the fixed frame  38  sense the relative position of the subframe  40  and accordingly send signals to the hydraulic cylinder  49  to extend and retract to oscillate the subframe  40  back and forth.  
         [0040]     In an alternate embodiment depicted in  FIG. 3C , the translating mechanism  48  includes a motor that drives a pair of sprocket. An endless loop chain engages with the pair of sprockets mounted to the subframe  40 . Position sensors mounted on either side of the fixed frame  38  sense the relative position of the subframe  40  and accordingly send signals to the motor to oscillate the subframe  40  back and forth. Those skilled in the art will recognize that other embodiments of the translating mechanism can be used, such as motorized wheels attached to the subframe  40 .  
         [0041]     At the entrance to the surface conditioner  10 , the fixed frame  38  supports drag pads  50  through which the strip S passes ( FIGS. 1 and 3 A). The pads  50  extend the full width of the strip S and can bear against both surfaces of the strip S with a force exerted by hydraulic motors  52  through leadscrews and an air bladder located behind the upper pad  50 . Normally during operation, the drag pads  50  do not bear against the strip S. However, once the trailing end of the strip S leaves the payoff reel  2  the bladders exert force on the pads  50  to bear against the strip S to create the tension on the strip S in place of the payoff reel  2 . At its discharge end, the fixed frame  38  supports pinch rollers  54  between which the strip S passes such that the rollers  54  bear against both surfaces of the strip S and maintain the strip S at a fixed elevation within the subframe  40  ( FIG. 3A ). Likewise at the entrance end the fixed frame  38  supports side rollers  56  that bear against the side edges of the strip S and prevent the strip S from displacing laterally.  
         [0042]     Drag pads  51  are also located directly before the recoiler  12  ( FIG. 1 ). These drag pads  51  bear against the strip S continuously during operation to insure that the strip S is tightly wound around the recoiler  12 .  
         [0043]     As mentioned above, the subframe  40  carries several cleaning modules  60  ( FIG. 3 ) which actually remove the scale from the strip S. Each cleaning module  60  contains ( FIG. 4 ) an upper brush  62  and a lower brush  64  which rotate against the upper and lower surfaces of the strip S directly opposite from each other, so that the tendency of the upper brush  62  to deflect the strip S vertically is offset by the lower brush  64  and visa versa. Preferably, the direction of rotation causes the surfaces of the brushes  62  and  64  at the area of contact with the strip S to move in the direction opposite the direction in which the strip advances. To this end, the brushes  62  and  64  are powered by an electric motor  66 , with the velocity of each brush  62  and  64  at the area of contact being between 3000 and 4000 ft/min and preferably about 3500 ft./min. Each brush  62  and  64  is longer than the strip S is wide—indeed, long enough for it to remain in contact with the strip S for the full width of the strip S as the subframe  40  moves back and forth on the tracks  44 . The translation back and forth across the strip S promotes more uniform wear in the brushes  62  and  64  and does not enable reoccurring imperfections in a particular region of the strip S from deforming the brushes  62  and  64 . This in turn decreases the frequency at which the brushes  62  and  64  need to be dressed, so that the brushes last longer. In some instances, the need to redress brushes  62  and  64  can be eliminated altogether.  
         [0044]     Each brush  62  and  64  possesses a generally cylindrical configuration about 14 in. in diameter. It includes ( FIG. 4 ) a core  68 , which is rotated by the motor  66 , and bristles  70  that radiate from the core  66 . The bristles  70  are nylon filaments impregnated with silicon-carbide, which possess a measure of flexibility. The flexibility of the bristles gives the brush the advantage of being compressible so that the brush compresses against the strip S during operation. This allows the bristles to remain in contact with the strip S even with variations in flatness, thereby, improving the performance of the surface conditioner  10 . Suitable brushes may be obtained fromDanline, Inc. located in Springfield, N.J., or Hotani Co., Ltd., located in Wakayama, Japan.  
         [0045]     A modified cleaning module  74  ( FIG. 6 ) has upper and lower abrasive rolls  76  and  78  that are offset with respect to each other along the strip S. The upper roll  76  bears against the upper surface of the strip S and the lower roll  78  against the lower surface. To prevent the offset rolls  76  and  78  from deflecting the strip S, a backing roller  80  bears against the strip S opposite each of them. The rolls  76  and  78  are powered and revolve such that their surfaces move against the direction of advance for the strip S. The backing rollers  80  merely rotate with the advance of the strip S owing to their contact with the strip S.  
         [0046]     Each roll  76  and  78  has a core  81  and a multitude of disks  82  set end to end along the core  76 . The disks  82  contain abrasive particles, such as aluminum oxide. Disk-like rolls sold by Minnesota Mining and Manufacturing (3M) under the trademark Scotch Brite will suffice for the rolls  76  and  78 . U.S. Pat. No. 6,814,815 describes the rolls  76  and  78  in greater detail.  
         [0047]     In lieu of offsetting the upper and lower rolls  76  and  78  of each module  74 , they may be positioned directly opposite each other, and this eliminates the need for the backing rollers  80 .  
         [0048]     Each cleaning module  60  or  74  carries a spray head  83  ( FIGS. 4-6 ), which directs water spread into a spray at the area of contact between the brushes  62  and  64  and the strip S. The water serves as a lubricant to reduce friction between the brushes  62  and  64  or  76  and  78  and the strip S, which promotes cooler running operation. In addition, the water serves to flush from the brushes  62  and  64  the scale that is removed from the strip S. The modified cleaning modules  74  are likewise equipped with spray heads  83 .  
         [0049]     Beyond the last cleaning module  74  and its spray heads  83  the fixed frame  38  of the surface conditioner  10  supports several air knives  84  ( FIG. 1 ) that direct high velocity air streams at both surfaces of the strip S to remove water from the strip S. Thus, the strip S advances to the recoiler  12  free of water, yet it is not coated with oil. Instead the wusite that remains on the cleaned surfaces of the strip S prevents oxidation at those surfaces.  
         [0050]     The recoiler  12  draws the strip S through the surface conditioner  10  and winds it into a coil C ( FIG. 7 ) all while maintaining tension on the order of 50,000 to 60,000 lbs. in the strip S for larger diameter coils and up to about 200,000 lbs. for smaller diameter coils. The tension of this magnitude further levels the strip S, making its surfaces flat enough for the brushes  62  and  64  or the rolls  76  and  78  to effectively remove both hematite and magnetic from the strip S. The leveler  6  offers the primary resistance to the force exerted by the recoiler  12 , although the drag pads  50  and  51  and the brake  20  of the payoff reel  2  offer some resistance as well.  
         [0051]     The recoiler  12  includes ( FIG. 7 ) a base  86 , a pair of pedestals  88  that are attached to the base  86 , a mandrel  90  that at one end rotates in the pedestals  88 , an electric motor  92  coupled to that end of the mandrel  90  through a gear reduction for rotating the mandrel  90 , and a retaining arm  94  that extends between the opposite end of the mandrel  90  and the base  84 . The rotating mandrel  90  winds the strip S about it into the coil C after the surface conditioner  10  has removed scale from the surfaces of the strip S. Moreover, the rotation of the mandrel  90  serves to maintain tension in the strip S and, thus, is subjected to substantial forces, which are transferred through the pedestals  88  and the retaining arm  94  to the base  86  which resists them. However, the retaining arm  94  is detachable from the end of the mandrel  90  to enable a fully wound coil C to be removed from the mandrel  90 .  
         [0052]     The mandrel  90  includes ( FIGS. 8-10 ) a tubular arbor  96 , one end of which is received in the pedestals  88  where it rotates in an antifriction bearing  98 . Beyond the pedestals  88 , the end of the arbor  96  is coupled with the electric motor  92 , so that when the motor  92  is energized, it will exert torque on and rotate the arbor  96 —indeed, the entire mandrel  90 . At its opposite end, the arbor  96  is fitted with a hub  100  provided with a journal that is received in a bearing carried by the retaining arm  94 . The hub  100  may be removed from the arbor  96  to expose the hollow interior of the arbor  96 .  
         [0053]     Within its hollow interior the arbor  96  contains an actuator assembly  102  having a pair of side plates  104  and hydraulic cylinders  106  located between the plates  104  and secured firmly to them. While the assembly  102  can float, so to speak, in the interior of the arbor  96 , it cannot rotate with respect to the arbor  96 . In other words, it has the capacity to shift a short distance along a single diameter in the arbor  96 .  
         [0054]     The strip S winds around the portion of the mandrel  90  that is located between the pedestal  88  and the retaining arm  94 , and in this segment the arbor  96  has an axially directed rib  110  over which a wedge bar  112  fits. The bar  112  has beveled faces  114  along its sides, thus imparting a wedge-shaped configuration to its exterior. The bar  112  also has rods  116  that project through the rib  110  and into the hollow interior of the arbor  96  where they align with the cylinders  106  of the actuator assembly  102 . Thus, when the cylinders  106  are energized, they urge the wedge bar  112  away from the arbor  96 .  
         [0055]     Directly opposite from the rib  110 , that is to say 180° from it, the arbor  96  has a land  120  against which a clamping block  122  is firmly secured. The clamping block  122  contains a channel  124  ( FIG. 10 ) that opens away from the arbor  96 , with one of the sides of the channel  124  being undercut to provide a recessed clamping surface  126  that is presented toward the arbor  96 . The channel  124  holds a clamping bar  130  having a clamping surface  132  that is presented opposite the clamping surface  126  on the block  122 . The clamping bar  130  has rods  134  that pass into the arbor  96  at the land  120  and terminate within the hollow interior of the arbor  96  where they also align with the cylinders  106  of the actuator assembly  102 . When the cylinders  106  are energized, they not only urge the wedge bar  112  away from the arbor  96 , but they also urge the clamping bar  130  toward the clamping surface  126  on the clamping block  122 .  
         [0056]     Attached firmly against the exterior surface of the arbor  96  along each side of the clamping block  122  are several pivot mounts  138  ( FIGS. 9 &amp; 10 ). They serve as mounts for fixed shoes  140  having arcuate exterior surfaces that lie flush with the exterior surface of the block  122 . The pivot mounts  138  also function as hinges for attaching expandable shoes  142  to the arbor  96 . The expandable shoes  142  have arcuate exterior surfaces that lie generally flush with the arcuate surfaces of the fixed shoes  140  at the pivot mount  138 . The arcuate span of the expandable shoes  142  exceeds the arcuate span of the fixed shoes  140 , and indeed is great enough to enable those edges of the shoes  142  that are remote from the mounts  138  to lie along the beveled faces  114  of the wedge bar  112 . Thus when the cylinders  106  are energized, the beveled faces  114  of the wedge bar  112  function as cams, so that the wedge bar  122  drives the expandable shoes  142  away from the arbor  96 . The end of the two expandable shoes  142  are connected with links  146  to restrict the distance that they can spread away from each other.  
         [0057]     The mandrel  90  receives the squared off edge of the strip S with the cylinders  106  of its actuating assembly  102  retracted. Indeed, the squared off edge is inserted into the channel  124  of the clamping block  122 , so that it lies between the clamping surface  126  of the block  122  and the clamping surface  132  on the clamping bar  130 . Thereupon, the cylinders  106  of the actuator assembly  102  are energized. They drive the clamping bar  130  farther into the channel  124 , causing the end of the strip S to become clamped between the clamping surfaces  126  and  132  on the block  122  and bar  130 , respectively. The cylinders  106  also drive the wedge bar  112  away from the arbor  96  and force the expandable shoes  142  away from the arbor  96 , thereby increasing the size of the mandrel  90 . The use of multiple cylinders  106  along the actuator assembly  102  provide a uniformly distributed force to the clamping bar  130  and the wedge bar  112 , which enhances the ability of the recoiler to handle the high tensions it places on the strip S and allows the clamping bar  130  to compensate for thickness variations in the strip S. At this juncture, the electric motor  92  may be energized to wind the strip S around the expanded mandrel  90  and thus draw it through the surface conditioner  10 .  
         [0058]     In operation of the apparatus A, the coiled sheet is withdrawn from the pay-off reel  10  in the form of the strip S and “threaded” into the crop shear  4 , which cuts off the leading edge. The strip S is threaded through the roller-leveler  6 , side-trimmer  8 , the surface conditioner  10 , and into the recoiler  12 .  
         [0059]     Changes can be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.