APPARATUS AND METHOD FOR GRINDING WORK ROLLERS

Cross Reference To Related Application

[0001 ] The present invention claims the benefit of U.S. provisional patent application

61/014,621 filed December 18, 2007 the entire contents and disclosure of which arc incorporated by reference as is fully set forth herein.

FIELD OF THE DISCLOSURE

[0002] One embodiment of the present invention relates in general to improvements in a grinding wheel and, in particular, to a peripheral grinding wheel used for resurfacing a coated or uncoated work rolls which are used for a rolling operation.

SUMMARY OF THE INVENTION

[0003] In one embodiment of the invention, a grinding wheel comprising a cylindrical hub of substantially rigid material has a first band of yieldable material on its circumferential surface, and a second band of abrasive material on the outer circumferential surface of the first band. The first band of yieldable material can be flexible or semi-flexible and provides support for the second band. The first band of yieldable material helps to reduce abrupt or sudden changes in pressure between the second band of abrasive material and the coated or uncoated surface of the cylindrical work roller when the grinding wheel is being used to recondition the surface of a work roller. This change in pressure may be caused by oscillating motion of the roller and/or the grinding wheel, or by high and/or low areas on the roller and/or the grinding wheel which limits the ability of the grinding wheel to grind the coated or uncoated surface of a cylindrical roller with a high degree of machining accuracy without causing undue wear to the surface of the work roller (coated or uncoated). An adhesive can be used to prevent slippage between the hub and the first band of yieldable material and between the first band of yieldable material and second band of abrasive material.

[0004] In another embodiment of the invention, a cylindrically shaped grinding hub of substantially rigid material has a first band of yieldable material located around its circumferential surface, and a second band of abrasive material located on the circumferential surface of the first band. The first band can be composed of urethane rubber of a desired

thickness and the second band can be abrasive particles which are either embedded into the surface of the first band or it can be an abrasive lapping belt located on the circumference of the first band. The first band of urethane rubber can be a solid tire having a desired firmness which is obtained by varying the density of the urethane rubber. In another embodiment, the tire can be hollow and have a desired firmness which can be obtained from using different urefhanes or by varying the thickness of the top, bottom and/or side walls of the tire. Adhesive can be used to prevent relative movement between the hub and the tire and between the tire and the second band of abrasive particles on the tire when the abrasive particles are in a belt and not embedded directly into the surface of the tire. In still another embodiment, the abrasive material can be embedded into the circumferential surface of the first band.

[0005] In another embodiment of the invention the width of the first band can be greater than the width of the pliable ring to form an overlap of the edges of the first band relative to the sides of the cylindrical shaped hub. The overlapping first band provides for a mechanism to reduce local contact load by distributing the load through the overlap.

[0006] In another embodiment of the invention, a grinding wheel comprises a cylindrical shape hub of substantially rigid material having a first band of yieldable material on its circumferential surface, and a second band of abrasive material on the circumferential surface of the first band. The first band can be composed of urethane rubber and the second band can be an abrasive lapping belt. In this embodiment the first band of urethane rubber can be a tire, the tire can take many forms from solid to hollow having a cross section which has a closed "O" shape or a partial closed "O" shape. The tire is fitted around the circumferential surface of the cylindrical hub as an automobile tire is fitted around an automobile wheel rim or by an assembly process discussed in detail below. In one embodiment when the first band has a partial closed "O" shape cross section which can resemble an automobile tire, the method used to seal an automobile tubeless tire to a rim can be used to provide an air tight seal between the hub and the first band. An air valve can be provided to admit air at a desired pressure into the tire to inflate it to a desired pressure. A second band of abrasive material can be provided by either embedding abrasive particles into the outer circumferential surface of the first band or by placing a belt having abrasive particles embedded therein onto the outer circumferential surface of the first band.

Optionally, an adhesive can be used to prevent relative movement between the hub and the first band, and also between the first band and the belt if used.

[0007] The foregoing has outlined, rather broadly, the preferred feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the ail should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the ail should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Other aspects, features and advantages of the present invention will become more fully apparent from the following detailed description, the appended claim, and the accompanying drawings in which similar parts have similar reference numerals where:

[0009] Fig. 1 is a side view of a grinding wheel in accordance with the principles of the invention;

[0010] Figs. I a and Ib are front views of contact areas of the present invention of Fig. 1 when engaged with the grinding surface;

[0011] Fig. 2a is a cross section view of the grinding wheel of Fig. 1 illustrating a substantially flat circumferential surface;

[0012] Fig. 2b is a partial cross section view of the grinding wheel of Fig. 1 illustrating another embodiment having a convex circumferential surface;

[0013] Fig. 3 is a side view of another embodiment of a grinding wheel of the invention;

[0014] Fig. 4 is a perspective view of the grinding wheel of Fig. 3;

[0015] Fig. 5 is a side view of still another embodiment of the grinding wheel;

[0016] Fig. 6 is a perspective view of the grinding wheel of Fig. 5;

[0017] Fig. 7 is an exploded view of one embodiment of the present invention;

[0018] Figs. 7A-N are illustrations of the assembly of one embodiment of the present invention shown in Fig. 7;

[0019] Fig. 8 shows the profiles of the surfaces of two cylindrical rollers as shipped to an aluminum alloy rolling mill;

[0020] Fig. 9 shows the profiles of the surfaces of the two cylindrical rollers of Fig. 7 after being used by an aluminum alloy rolling mill;

[0021] Fig. 10 shows the profiles of the surfaces of two cylindrical rollers of Fig. 9 after being resurfaced with the new grinding wheel here disclosed;

[0022] Fig. 1 IA and 1 IB are flow charts illustrating the process to dress or prepare the pliable ring of one embodiment illustrated in Fig. 7 prior to the grinding operation;

[0023] Figs. 12A-D are illustrations of the pliable ring outer surface before, during, and after the dressing process; and

[0024] Figs. 12E and F are illustrations of one embodiment of an abrasive belt that overlaps the edge of the pliable ring.

DETAILED DESCRIPTION

[0025] One embodiment of the present invention is illustrated in detail in Figures 1 and 2.

Grinding wheel 20 may include a hub 22 composed of a structural material such as aluminum, iron, a plastic or the like having a centrally located bore 24 adapted to receive a drive shaft of a rotational device (not shown). Hub 22 is generally cylindrical with a predetermined radius Rl , thickness Tl, and length Ll suitable for the loading conditioning of the grinding process, which can take into account the mechanical properties and other characteristics of the substrate, coating, film, metal or other surface to be ground. In this embodiment and all embodiments which are disclosed herein, or their equivalents, the hub can be rigid, partially rigid or yieldable. As shown

in Fig. 2A, circumferential surface contour 25 of hub 22 can be substantially flat and adaptable to receive a first band 28 of a yicldable or flexible material. The elastic, resilience or yieldable properties of the first or subsequent bands or hub 22 singularly or in combination result in the contact area of the present invention with the grinding surface to be adjustable from the line contact to a contact area A illustrated in Fig. IA to generally conform to the shape (such as rectangular shape) of the coated or uncoatcd surface to be ground and to modify the shape only enough to remove or sacrifice the high points (typically approximately ranging from 1 μm to 10 μm of the coating) and not to remove the good coating with many hours of useful life remaining or metal surface (if not coated). The shape of the contact area A can vary depending on the flatness of contour 25. For example, contact area A can be oval as shown in Fig. Ib, which corresponds to contour 25 of Fig. 2b.

[0026] Alternatively, circumferential surface contour 25 can be convex (Fig. 2B). The intersection point 27 of outer wall 29 of hub 24 and circumferential surface contour 25, as shown in Fig. 2B, may be a smooth transition point such as a rounded comer or edge having a predetermined radius R2 to minimize marking, scoring, or deforming of the surface to be ground as the grinding wheel longitudinally traverses or moves along the grinding surface length. Intersection point 27 can be on one or both outer walls 29 of hub 24, Other embodiments of the present invention can include similar intersection points (not shown) between any layered surface positioned on surface 25 (flat, convex, or concave), outer wall 29, or other layers positioned thereon to be discussed in detail below.

[0027] The embodiment shown in Fig. 1 will be discussed in detail for illustration purpose only and is not intended to limit the claimed invention. The disclosed details of the embodiment can be adapted for use with any circumferential surface contour 25 such as convex surface 25 (Fig. 2B).

[0028] Now returning to Fig. 1, the first band 28 is located around the circumference 25 of the hub 24 and can be coupled to the hub 24 with an adhesive 30. The first band 28 can be composed of rubber, paper fiber or any other suitable material which provides a yieldable resilient or flexible support member for a second band 32 of abrasive material which is located on the circumference 28a of the first band 28, In one first band 28 embodiment, first band 28 is a not

inflatable (as shown in Figs. 1-4) and discussed in detail herein. An inflatable band embodiment will be discussed in detail below. Notwithstanding that many of the discussed novel and inventive features are directed to first band 28 or hub 22, it is to be understood that inflatability, non- inflatability, yicldability, resiliency, flexibility, or circumferential surface contours are also adaptable to subsequent bands or layer singularly or in combination to produce the desired results.

[0029] In the case where circumferential surface 25 is substantially flat, then circumferential surface 28a of first band 28 (or any subsequently attached, connected, or adhered bands or layers) can have convex or convex/concave profiles as shown in Figs. 2B and 12D and explained in detail above for the contoured circumferential surface 25, which can be adapted for use with the bands or layers. A sufficiently yieldable, resilient, or elastic material (hereinafter referred to as resilient) can be defined for the purpose of this application as material that expands or elongates more than 5% of its original diameter or circumference or narrows in width or locally compresses relative to original Hub radius in the contact area by more than 5% when the abrasive medium or material contacts the work roll surface, A suitable yieldable material can be, for example, of about 50 to 95 Durometer and a thickness of 0.5 to 2.0 inches. However, the thickness of the yieldable material will depend on the width and desired rigidity of the structure. The second band 32 can be a continuous belt containing abrasive material or particles which can extend fully through the belt or are only on the top surface of the belt. The belt 32 can be attached to the circumferential surface 28a of the yieldable first band 28 with an adhesive 26, shown as a line in Fig. 1. One embodiment of second band 32 is not made of a resilient material and is commercially available under 3M 663FC Trizact Diamond cloth, Eastwind abrasive belts, or 3M films or belts. Another embodiment of second band 32 is made of a resilient material similar to first band 28. The abrasive materials particles can be diamonds, hard chromium, tungsten carbide, boron nitride or any other abrasive material which is selected by a user. In another embodiment, the abrasive material or particles can be embedded in the circumferential surface 28a of the first band 28. In this embodiment, the circumferential surface 28a of the yieldable first band 28 will include the abrasive particles and the embedded particles become the second belt.

[0030] In another alternative of the present invention illustrated in Figs. 3 and 4 the first band 28 can be made of a resilient, yieldable material such as urethane rubber in either solid or

hollow form (not inflatable) and the firmness of the first band 28 can be set to a desired value by varying the density of the urethane, or by making the band hollow, cither with or without vent openings, or by varying the thickness of the top, bottom and/or side walls of a hollow band. Second band or belt 32 which can be a continuous band of abrasive material or particles which can be embedded into and extend fully through first band 28 or are embedded only into the top surface of the first band 28. Second band or belt 32 can be attached to the circumferential surface of the yieldable first band 28 with an adhesive 26, shown as a line in Fig. 3. The abrasive particles can be of a desired material such as diamonds, hard chromium, tungsten carbide, boron nitride or any other abrasive material which is selected by a user. In another embodiment, the abrasive material can be embedded in the circumferential surface of the first belt 28. In this embodiment, the circumferential surface of the yieldable first band will include the abrasive material and this layer will become the second band. The hub 24 is the same material and configuration as discussed above and shown in Fig, 1.

[0031] In another embodiment of the present invention illustrated in Figs. 5 and 6, there is disclosed a grinding wheel 20 for grinding the surface of a coated or uncoated cylindrical work roller used in a rolling mill. The grinding wheel 20 comprises a hub 22 composed of a material such as aluminum, iron, a plastic or the like having a centrally located bore 24 as shown in Fig. 1 for receiving a drive shaft (not shown). The circumferential surface of the hub can be substantially flat or configured to have a concave shape which is similar to an automobile wheel rim for a tubeless tire. A first band 36 which can be composed of a yieldable or flexible material is located around the circumference 25 of the hub 22 and is coupled to rotate with the hub 22. The first band 36 can be composed of urethane rubber, or any other suitable material which provides a yieldable or flexible support member for a second band 32 of abrasive material which is located around the circumference of the first band 36. The first band 36 of urethane rubber can be a tire having a cross section with either a closed "O" shape or partial opened "O" (or a C-shape). When the first band 36 has a partial closed "O" shaped or C-shaped cross section, the method used to couple and seal an automobile tubeless tire to an automobile wheel rim can be used to both couple the first band 36 (also referred to as tire) to the rim and provide an air tight seal between the tire 36 and the hub 22, Where the first band 36 is a tire having a closed "O" shaped cross section, the tire 36 can be fitted around the circumference of the hub and coupled to the hub with an adhesive to prevent relative movement between the tire and the hub or other conventional

lire/rim attachment methods. With either type of tire, an air valve (not shown), can be provided to allow air under pressure to be fed to the interior of the tire to control its firmness.

[0032] The interior of the tire with the closed "O" shaped section is defined as the inner surface of the tire. The interior of the tire with the partially opened "O" shaped or "C" shaped is defined as the inner surface of the tire and the circumferential surface 25 of hub 22. With regards to elastic, yieldable, and resilient layers, what other materials have these qualities and abrasive qualities. Thus, by varying the air pressure in the tire 36, its firmness can be set to a desired value. A second band 32 which can be a continuous loop or belt which contains abrasive particles which are embedded into and extend either fully into the second band or only partially into the top surface of the band. The second band 32 is located on the circumferential surface 28a of the yieldable first band 36 and can be secured to the first band 36 with an adhesive 26, shown as a line in Fig. 5, to prevent relative movement between the first band 36 and second band 32, The abrasive particles can be diamonds, hard chromium, tungsten carbide, boron nitride or any other abrasive material which is selected by a user. In another embodiment, the abrasive material can be embedded in the circumferential surface 25 of the first band 36. In this embodiment, the circumferential surface 25 of the yieldable first band 36 will have the layer or band of abrasive material, and this layer or band becomes the second band 32.

[0033] Another embodiment of the present invention is denoted by reference number 70 illustrated in Fig. 7. Grinding wheel 70 includes hub 72 having channel 73 to receive protective liner 76 (optional) and inner tube 80. Pliable ring 94 slides over outer perimeter surface 102 of hub 72 and is secured in place by opposing outer rings 104, 124, which are attached to ends 72a, 72b of hub 72.

[0034] Now turning to Figs. 7A-N for an example of an assembly of one of the embodiments of the present invention. Fig, 7 A illustrates hub 72 being placed on two spacers 74 to elevate hub 72 above a work surface. Figs. 7B-C illustrate protective liner 76 being placed within the inner diameter 78 of inner tube 80. Protective liner 76 can be a general flat strip of resilient material having a length approximately equivalent to the circumference of the inner diameter 78 of inner tube 80 and a thickness sufficient to form a barrier between inner diameter

of the strip can be connected to form a loop or hoop structure. Fig. 7D is a top view of Fig. 7 C illustrating air valve 82 of inner tube 80 being inserted into liner hole 84 of protective inner 76. Fig. 7E illustrates optional 0-rings 86 to improve sealing and prevent air leakage and relative movement. For example, a large o-ring is assembled first followed by one or more small O-rings. Though four O-rings of various sizes are shown, it is not intended to limit the invention by the number of O-rings or size as represented herein. Fig. 7F illustrates an optional sealant 88 (for example, Loctite© super flex RTV Clear Silicon Adhesive) applied to all O-rings 86 and at base 82B of air valve 82. Fig. 7G illustrates inner tube 80 being placed around inner surface 81 of hub 72 such that protective liner 76 (Figs. 7B-F) is disposed between inner diameter 78 of inner tube 80 and inner surface 81 of hub 72. Fig. 7H illustrates air valve 82 being inserted into air valve hole 90 of hub 72 from the inner surface 81 side inward towards inner diameter 92 of hub 72 (Fig. 7G). Fig, 71 illustrates pliable ring 94 being placed over the entire hub 72, whereas diameter 96 of inner surface 98 of pliable ring 94 is slightly larger than the diameter 100 of outer perimeter surface 102 of hub 72. Inner tube 80 is substantially free of air during the assembly of pliable ring 94 onto hub 72 such that inner tube 80 is not pinched or otherwise damaged during assembly. Fig. 7 J illustrates outer ring 104 being placed on top of one side of hub 72 to secure pliable ring 94 in place, whereas the diameter 106 of outer surface 108 of outer ring 104 is sufficient to retain pliable ring 94 in place during each operational stage, such as inflated, deflated, static (at rest), and dynamic (rotating). The only limitation on diameter 106 is that it cannot contact the roll surface being ground during the grinding operation. This can be accomplished as long as diameter 106 is less than diameter 110 of outer surface 112 of pliable ring 94 when inner tube 80 is inflated to operational conditions and outer surface 112 is in contact with the roll surface to be ground. Screws 114 are inserted into holes 116 of outer ring 104 and screwed into holes 118 of hub 72 to secure outer ring 104 to hub 72, and thereby retaining pliable ring 94 on one side of hub 72, Fig. 7K illustrates pliable ring 94 being lifted up to contact outer surface 120 of outer ring 106 to form assembly 122, Fig, 7L illustrates assembly 122 after being turned over to expose the opposite side of the assembly for assembly of the second outer ring 124. Screws 126 (which can be the same configuration as screws 114) are inserted into holes 128 (which can be the same configuration as holes 116) of second outer ring 124 and screwed into holes 130 (which can be the same configuration as holes 1 17) of hub 72 to secure outer ring 124 to assembly 122, and thereby retain pliable ring 94 on the other side of hub 72, to form inflatable hub embodiment 130, Fig. 7M

illustrates inflatable hub embodiment 130 being connected to a compressor at an air valve (not shown) and inflated to a predetermined pressure, for example 35 PSI. An abrasive belt (not shown) can be place around outer surface 1 12 before or during the inflation of inner tube 80. The predetermined pressure will determine the tension in the abrasive belt. Fig. 7N is a perspective view of inflatable hub embodiment 130. Hub 72 and outer ring 104/124 can be made of any rigid material (such as metal, polymer, or composite) suitable to operate under the operational load conditions. The above example is not intended to limit the invention to a particular method or sequence of events or an embodiment but only to provide an illustration of one possible assembly sequence of one configuration of the inflatable hub embodiment.

[0035] Prior to attaching the abrasive belt to pliable ring 94 for the first time, pliable ring

94 must be dressed or prepared to customize the flatness of outer surface 1 12 for the desired contact area A, as discussed above. The dressing procedure is shown in Figs. 1 IA and 1 IB. The pre-dressed outer surface 112 of pliable ring 94 is shown in Fig. 12A. The first step is to assemble the grinding wheel up to the attached pliable ring 94 to hub 72, as shown in Fig. 7N. Next, grinding wheel is installed on to the rotation device without the abrasive belt. Conventional inspection techniques are employed to check the run-out of the hub inner surface 81. The run-out of the hub can also be determined by the run-out of the diameter of outer surface of outer rings 104, 124 since the attached components are substantially concentric. Acceptable run-out is determined based on design specifications, for example from 0.001 inches to 0.010 inches. Once the hub is determined to be within acceptable run-out, then the inner tube 80 is inflated to desired pressure and the outer surface 1 12 of pliable ring 94 bulges radially outward as shown in Fig. 12B. An abrasive pad is adhered to the roll of the work roll to be ground or a shop work roll. The roll and rotation device are turned on and brought up to a predetermined rotational speed. The outer surface 1 12 of pliable ring 94 is brought in contact with the abrasive pad on the roll. After a predetermined time period of contact the outer surface 112 of pliable ring 94 is checked for flatness (F) and roundness (R) using conventional measurement equipment (see Fig. 12C), wherein w is the width of the flat zone and E is the distance from the edge of the flat zone to the outer edge of the pliable ring. If the flatness and roundness are not acceptable, then the contact step is repeated. Inner tube 80 is deflated once the flatness and roundness are acceptable to a predetermined pressure such that the abrasive belt is installed on to the outer surface 112 of pliable ring 94. One embodiment of the outer surface 112 of pliable ring 94 is concave as shown

in Fig. 12D. To accomplish this configuration the roll and the rotation device are turned off and the abrasive pad is removed from the roll. Inner tube 80 is then inflated to the operational pressure to secure the abrasive belt to the grinding wheel.

[0036] The next step in the dressing procedure is to check the contact area. The roll and rotation device are turned on. The roll can be either the roll to be ground or a shop work roll. The outer surface 112 of pliable ring 94 is advanced towards the roll a predetermined distance to contact the roll to form a contact area on to the roll. The hub is withdrawn and the contact area including length, depth, width, corner radii, edges or sides and general geometric shape (for example oval or rectangular) is measured or compared to a standard or desired shape. One measurement technique compares the actual contact area width to a predetermined percentage of the pliable ring width, for example contact area width between 66% and 100% of pliable ring width. If the contact area meets the criterion, then the grinding process can begin and the abrasive pad can be replaced as required without dressing outer surface 112 of pliable ring 94 again.

[0037] One aspect of the invention provides for a varying width relationship between hub

72, pliable ring 94, and abrasive belt 32. A substantially 1: 1 width relationship is shown in FIG. 12A, where width Wl of hub 72 is substantially equal to width W2 of pliable ring 94. FIG. 12E is an exaggerated exploded view of pliable ring 94 deflated prior to assembly of the abrasive belt 32. FIG. 12F is a view of the abrasive belt 32 assembled on to the pliable ring 94 after the pliable ring 94 is inflated. FIGS. 12E and F illustrate width W3 of abrasive belt 32 having a width less than width W2 of pliable ring 94, which results in an overlap 132A, 132B of edges 134A, 134B of abrasive belt 32 relative to the outer surface 136A, 136B of pliable ring 94, Overlap 132 A, 132B of abrasive belt 32 further minimizes edge contact marks on the surface of the work roll being ground allowing contact zone 138 to span the full width W2 of pliable ring 94 from outer surface 136A to outer surface 136B. Abrasive belt 32 can depress as required into pliable ring 94 to absorb and distribute the contact load through overlap 132A, 132B. One embodiment of the present invention having overlap 132A, 132B can have abrasive material located on the circumferential surface of abrasive belt 32, as disclosed above. Another embodiment of the present invention having overlap 132A, 132B can include a removable abrasive band can be assembled on to abrasive belt 32.

[0038] However, when the contact area does not meet the criterion, then corrective action can be taken, as shown in Fig. HB. When the contact area is centered and is too small or narrow, then the inner tube pressure must be decreased. When the contact area extends to the edges and is too wide, then inner tube pressure must be increased. Increasing or decreasing the inner tube pressure will selectively tune or customize the contact area. Alternatively, the process may require repeating the procedure starting with checking the run-out of the hub.

[0039] In operation, one embodiment of the present invention will coordinate the roll rotation with the lateral traverse of the abrasive belt across the roll surface to equal 1 roll revolution per Vi width of pliable ring lateral displacement. This will result in a 50% overlap in the contact area for each roll revolution and a smooth translation of the grinding wheel along the roll surface. The synchronization of the roll revolution with the perpendicular traversal of the grinding wheel traversal along the roll surface from left to right illustrates the cooperative interaction of the roll with grinding wheel. Whereby, the roll surface will be substantially free of scoring and marking due to the edges or other anomalies of the abrasive belt.

[0040] Referring to Fig. 8, there is shown in side-by-side positions the profiles of two cylindrical work rollers prior to being shipped to a mill for use in rolling aluminum alloy. Note that the surface of each coating has a convex crown and is substantially free of irregularities.

[0041] Fig. 9 shows the profiles of coatings on the same two cylindrical work rollers after being used by a mill on aluminum alloy.

[0042] Fig. 10 shows the profiles of the two returned cylindrical work rollers after they were resurfaced using an embodiment of the present invention. It is to be noted that the as- shipped and as-ground profiles are almost identical to the profiles of the new cylindrical work rollers shown in Fig. 7 and are now substantially free of all irregularities.

[0043] While there has been described herein the principles of the invention, it is to be clearly understood to those skilled in the art that this description is made only by way of example and not as a limitation to the scope of the invention. Accordingly, it is intended to cover all modifications of the invention which fall within the true spirit and scope of the invention.