Backup Pad

Abstract

A method for adjusting contact pressure across an abrasive disc is presented. The method includes coupling an abrasive disc to a back-up pad with pressure-regulating features that equalize the pressure experienced by the work surface across the radius of the abrasive disc. The method also includes abrading the work surface by contacting the abrasive disc with the work surface. The back-up pad produces an abrasive disc with a cut rate that is substantially uniform across the surface of the abrasive disc, compared to an abrasive disc on a back-up pad that does not have the pressure-regulating features.

Description

[Background technology]

[0001] Abrasive fiber discs typically have an abrasive layer on a vulcanized fiber backing. In one common use, the abrasive fiber disc is attached to a backup pad driven by the rotating motorized shaft of the angle grinder. The backup pad allows the operator to apply pressure toward the work surface being polished while reducing pressure, angle, and surface variations. Some such backup pads have raised ridges that can increase pressure compared to adjacent portions of the disc and provide channels for debris to escape against the work surface being polished, thereby resulting in an increased polishing rate. When abrasive discs wear out and are replaced, they are removed from the backup pad, which can often be reused several times before being discarded. Summary of the Invention

[0002] A method for managing contact pressure across an abrasive disc is presented. The method includes coupling an abrasive disc to a back-up pad with pressure-regulating features that equalize the pressure experienced by the work surface across the radius of the abrasive disc. The method also includes abrading the work surface by contacting the abrasive disc with the work surface. The back-up pad results in an abrasive disc with a cut rate that is substantially uniform across the surface of the abrasive disc, compared to an abrasive disc on a back-up pad that does not have the pressure-regulating features. [Brief explanation of the drawings]

[0003] The drawings, which are not necessarily drawn to scale and in which like numerals may refer to like elements in different drawings, illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0004] [Figure 1A]FIG. 1 illustrates an abrasive disc assembly mounted on a drive shaft of a power tool and its associated parameters. [Figure 1B] FIG. 1 illustrates an abrasive disc assembly mounted on a drive shaft of a power tool and its associated parameters. [Figure 1C] FIG. 1 illustrates an abrasive disc assembly mounted on a drive shaft of a power tool and its associated parameters. [Figure 2A] FIG. 1 illustrates an abrasive disc mounting assembly having a pressure adjusting feature of non-uniform thickness. [Figure 2B] FIG. 1 illustrates an abrasive disc mounting assembly having a pressure adjusting feature of non-uniform thickness. [Figure 2C] FIG. 1 illustrates an abrasive disc mounting assembly having a pressure adjusting feature of non-uniform thickness. [Figure 2D] FIG. 1 illustrates an abrasive disc mounting assembly having a pressure adjusting feature of non-uniform thickness. [Figure 2E] FIG. 1 illustrates an abrasive disc mounting assembly having a pressure adjusting feature of non-uniform thickness. [Figure 3A] FIG. 1 illustrates an abrasive disc mounting assembly having a concentric ring pressure adjustment feature. [Figure 3B] FIG. 1 illustrates an abrasive disc mounting assembly having a concentric ring pressure adjustment feature. [Figure 4A] FIG. 1 illustrates an abrasive disc mounting assembly having an uneven surface. [Figure 4B] FIG. 1 illustrates an abrasive disc mounting assembly having an uneven surface. [Figure 4C] FIG. 1 illustrates an abrasive disc mounting assembly having an uneven surface. [Figure 5] 10A-10C illustrate a method for providing a uniform cutting rate, according to embodiments herein. [Figure 6] 1 is a schematic diagram of a robotic paint repair in which embodiments of the present invention are useful; [Figure 7]FIG. 1 is an exploded view of the components of a robotic paint repair stack. [Figure 8A] FIG. 1 illustrates a tool and corresponding pressure profile for a robotic polishing operation. [Figure 8B] FIG. 1 illustrates a tool and corresponding pressure profile for a robotic polishing operation. [Figure 9A] 1 illustrates a tool for providing a patterned cutting rate using a robotic repair unit according to embodiments herein. [Figure 9B] 1 illustrates a tool for providing a patterned cutting rate using a robotic repair unit according to embodiments herein. [Figure 9C] 1 illustrates a tool for providing a patterned cutting rate using a robotic repair unit according to embodiments herein. [Figure 9D] 1 illustrates a tool for providing a patterned cutting rate using a robotic repair unit according to embodiments herein. [Figure 9E] 1 illustrates a tool for providing a patterned cutting rate using a robotic repair unit according to embodiments herein. [Figure 9F] 1 illustrates a tool for providing a patterned cutting rate using a robotic repair unit according to embodiments herein. [Figure 9G] 1 illustrates a tool for providing a patterned cutting rate using a robotic repair unit according to embodiments herein. [Figure 10] 10A-10C illustrate a method for providing a patterned cut rate using a robotic polishing system according to embodiments herein. [Figure 11A] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 11B] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 11C]Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 11D] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 11E] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 11F] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 11G] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12A] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12B] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12C] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12D] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12E] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12F] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12G] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12H] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12I]Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 12J] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 13A] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 13B] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 13C] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 14A] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 14B] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 14C] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. [Figure 14D] Figures relating to the configurations of the Examples and Comparative Examples and results discussed in more detail in the Examples section below. DETAILED DESCRIPTION OF THE INVENTION

[0005] As used herein, the terms "compressible" or "incompressible" refer to a material property of an object (e.g., an elastomeric outer layer), i.e., compressibility, which is a measure of the relative volume change of a material in response to pressure. For example, the term "substantially incompressible" refers to a material having a Poisson's ratio greater than about 0.45.

[0006] The term "elastically deformable" refers to the ability of a deformed object (e.g., an inner layer of synthetic foam) to recover substantially 100% (e.g., 99% or more, 99.5% or more, or 99.9% or more) to its original, undeformed state.

[0007] In this application, the term "polymer" or "polymers" includes homopolymers and copolymers, as well as homopolymers or copolymers that may be formed in miscible blends, for example, by coextrusion or by reaction, including, for example, transesterification. The term "copolymer" includes random copolymers, block copolymers, and star (e.g., dendritic) copolymers.

[0008] The term "pressure regulation feature" as used herein refers to a component of an abrasive backup pad assembly. This feature is permanently or temporarily attached to the side of the rigid backup component of the assembly opposite the spindle on the other side of the rigid backup component used to connect the assembly to a power tool. The abrasive disc is attached to the free surface of the "pressure regulation feature" away from the rigid backup component during the abrasive process. The "pressure regulation feature" is substantially softer than the rigid backup component of the assembly and therefore experiences substantial deformation compared to the rigid backup component when the assembly is engaged with a work surface during the abrasive process. The primary role of the "pressure regulation feature" in an abrasive backup pad assembly during the abrasive process includes, but is not limited to, uniformly distributing contact pressure between the pad assembly and the desired portion of the work surface from which material is to be removed, damping contact pressure fluctuations caused by disturbances such as irregularities in the work surface, non-uniformity of the abrasive disc, and vibrations of the abrasive power tool, as well as heat and debris management.

[0009] In this application, the term "about" or "approximately" with reference to a numerical value or shape means ±5 percent of the numerical value or property or characteristic, but expressly includes the exact numerical value. For example, a modulus of elasticity of "about" 200 psi refers to a modulus of elasticity between 190 and 210 psi, but also expressly includes a modulus of elasticity of exactly 200 psi.

[0010] In this application, the term "substantially" with respect to a property or characteristic means that the property or characteristic is exhibited to a greater extent than the opposite of the property or characteristic is exhibited. For example, a "substantially" transparent substrate (e.g., web) refers to a substrate (e.g., web) that transmits more radiation (e.g., visible light) than it does not transmit (e.g., absorbs and reflects). Thus, a substrate (e.g., web) that transmits more than 50% of the visible light incident on its surface is substantially transparent, while a substrate (e.g., web) that transmits 50% or less of the visible light incident on its surface is not substantially transparent.

[0011] 1A and 1B, a typical abrasive disc mounting assembly 100 includes a back-up pad 110 and a clamping assembly 140 that secures the abrasive disc 20. The connection can be by screw, key, bolt, friction, or any number of suitable fastener options known to those skilled in the art. The abrasive disc mounting assembly 100 includes an outward-facing, centrally located fastening member 130 (shown as a threaded bore, see FIG. 4) that is adapted to engage a threaded drive shaft 10 of a power tool (not shown), such as an angle grinder. The back-up pad 110 may have ribbed protrusions on the disc-engaging surface that provide additional support for the abrasive disc 20. During abrasion of a work surface, the drive shaft 10 rotates about an axis of rotation (115) during use.

[0012] As shown in FIG. 1C , as the abrasive disc 20 rotates in direction 30 during the abrading operation, both the linear velocity profile 40 and the material removal rate profile 50 (assuming constant pressure applied between the abrasive disc 20 and the work surface) exhibit higher linear velocities and higher removal rates with increasing distance from the center of the disc. This increases the non-uniform cut rate across the surface of the abrasive disc 20 from the center of the disc toward the outer periphery of the disc. In addition, wear on the abrasive disc 20 is non-uniform, with faster wear occurring on the outside, causing a further non-uniform cut rate across the surface of the abrasive disc as the abrasive disc wears. In human-operated abrading operations, it is often desirable to have a uniform cut rate along a radius extending from the center to the edge of the abrasive disc. However, it is expressly contemplated that for some abrading operations, it may be desirable to have a non-uniform patterned cut rate. While the embodiments described in FIGS. 2-7 are directed to achieving a patterned cut rate that is uniform across the surface of the abrasive disc 20, it is expressly contemplated that those skilled in the art can adapt them to produce non-uniform or other patterned cut rates. For example, patterned cut rates can be useful for managing debris removal, heat generation, cut rate blending, cut rate feathering, reducing secondary scratches, and avoiding haze.

[0013] 1A and 1B show a conical back-up pad 110. However, it is expressly contemplated that other back-up pad designs can also benefit from the embodiments discussed herein. For example, FIGS. 3A-3B show a flat back-up pad 304. Different back-up pad designs and configurations may be useful for different applications. For example, a conical design may be useful for volume displacement when significant material is being removed or added. Additionally, different material configurations may be important due to the compressibility or flexibility needs of a given application.

[0014] 2A-2E illustrate an abrasive disc mounting assembly having a pressure adjustment feature of non-uniform thickness. FIG. 2A is a perspective view of assembly 200, which includes a spindle 210 coupled to a conical back-up pad 220, which is coupled on a first side to a pressure adjustment feature 230 having a conical cavity substantially matching the conical back-up pad 220. The pressure adjustment feature 230 is coupled to the back-up pad 220 on a first side and receives an abrasive disc on an opposite side 240. The abrasive-receiving side 240 is substantially flat in some embodiments, as shown in FIGS. 2B and 2C. FIG. 2B illustrates a side view 225 of assembly 200. FIG. 2C illustrates a cutaway view 250 of assembly 200 along section line 2C-2C shown in FIG. 2B. As shown, the pressure regulation feature 230 substantially equalizes the depth 224 of the back-up pad 220 along the width 222 of the assembly 200 .

[0015] Figure 2D shows a graph of contact pressure against a work surface along the radius of a back-up pad designed similarly to that of Figure 2C. As shown, the contact pressure decreases along the radius of the back-up pad from the center of the disk to the outer periphery of the disk.

[0016] FIG. 2E illustrates an exemplary relative configuration of the back-up pad 280 and the pressure regulation feature 290, e.g., as a cutaway view similar to FIG. 250. As the relative portion of the height 294 corresponding to the pressure regulation feature 290 decreases, the relative portion of the back-up pad 280 increases. In some embodiments, the pressure regulation feature 290 is at least a portion of the depth 294 along the entire radius 272. In some embodiments, the surface 284 of the pressure regulation feature 290 is straight. The abrasive disc 286 can be attached to the surface 284 of the pressure regulation feature 290. In some embodiments, the interface 282 between the back-up pad 280 and the pressure regulation feature 290 at any point along the radius 272 is straight with a constant slope. The slope of the interface 282 can be selected based on the desired profile of contact pressure on the abrasive disc 286 along the radius 272 when the pad assembly 270 is compressed against the work surface during the abrasive process. Although not shown in FIG. 2E, in some embodiments, the pad assembly 270 may include a channel extending between the surface 284 of the pressure adjustment feature 290 to which the abrasive disc is attached and the opposite surface of the assembly on the back-up pad 280 for drawing out dust and debris.

[0017] The exact configuration and hardness of the pressure regulation feature 290 can vary based on the desired contact pressure profile between the abrasive disc 286 and the work surface during the abrading process. Lower contact pressures can be obtained by using softer materials. Also, more variation in the thickness of the pressure regulation feature 290 across the pad radius causes more variation in contact pressure across the pad that may be needed to obtain the desired cut profile.

[0018] Both components of the back-up pad 280 and the pressure regulation feature 290 should be made from suitable durable materials. Examples of materials for the back-up pad 280 include engineering plastics (e.g., nylon, polyphenylene sulfide, polyether ketone, polyether ether ketone, polycarbonate, high density polyethylene, high density polypropylene, polyester, polyurethane, etc.), polymer composites, metals, ceramic composites, and combinations thereof.

[0019] The material used in pressure regulation feature 290 may be substantially softer than the material used in back-up pad 280. This softness may be achieved in several ways, such as by selecting a material with a lower hardness (as indicated using any suitable hardness scale, such as Shore A or Shore 00), by selecting a material with a lower modulus of elasticity, by selecting a material with a higher compressibility (typically quantified by the material's Poisson's ratio), or by modifying the structure of a softer material to contain multiple gas inclusions, such as a foam or sculpted structure. In some embodiments, pressure regulation feature 290 may comprise a material with a hardness (as measured using ASTM D2240) of less than about 50 Shore A, less than about 40 Shore A, and optionally less than about 40 Shore A. In some embodiments, the material used in pressure regulation feature 290 may have a modulus of elasticity of less than about 500 psi, less than about 400 psi, or optionally less than about 200 psi. In some embodiments, the compressibility of the pressure regulation feature 290 can be measured via a compression force deflection test per ASTM D3574 when the pressure regulation feature is a foam, and via a compression deflection test per ASTM D1056 when the pressure regulation feature is a soft, spongy material such as a sponge or an expandable rubber. The pressure regulation feature 290 can have a compressibility of less than about 60 psi at 25% deflection, optionally less than about 45 psi at 25% deflection. The pressure regulation feature 290 is configured to be elastically deformable, e.g., capable of recovering substantially 100% (e.g., 99% or more, 99.5% or more, or 99.9% or more) to its original state after being deformed. In some embodiments, the pressure regulation feature 290 can be compressible (i.e., have a Poisson's ratio less than 0.2 or less than 0.1) to provide the desired deformability. In some embodiments, the pressure regulating feature 290 may be substantially incompressible, e.g., the relative volume change of the material in response to contact pressure is less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.2%, but is sufficiently soft to provide the desired deformability.In some embodiments, pressure regulating feature 290 may be made of a substantially incompressible material that is patterned, 3D printed, embossed, or engraved to provide the desired deformability. In some embodiments, pressure regulating feature 290 may have a Poisson's ratio of less than about 0.5, less than about 0.4, less than about 0.3, or preferably less than about 0.2. In some embodiments, pressure regulating feature 290 may have a negative Poisson's ratio.

[0020] In some embodiments, pressure regulation feature 290 may include one or more of the following materials: foam; a carved, structured, 3D printed, or embossed elastomer; a woven or nonwoven layer; or soft rubber. Suitable foams may be open-cell or closed-cell, including, for example, synthetic or natural foams, thermoformed foams, polyurethane, polyester, polyether, filled or grafted polyether, viscoelastic foam, melamine foam, polyethylene, cross-linked polyethylene, polypropylene, silicone, ionomer foam, etc. Pressure regulation feature 290 may also include foamed elastomers or vulcanized rubbers, including, for example, isoprene, neoprene, polybutadiene, polyisoprene, polychloroprene, nitrile rubber, polyvinyl chloride and nitrile rubber, ethylene-propylene copolymers such as EPDM (ethylene propylene diene monomer), and butyl rubber (e.g., isobutylene-isoprene copolymer). Suitable foam pressure regulating features 290 may have, for example, a compressibility of less than about 60 psi at 25% deflection, or less than about 45 psi at 25% deflection. It should be understood that pressure regulating features 290 may include any suitable compressible structure, such as, for example, a spring, a nonwoven, a woven fabric, an air bladder, etc. Some pressure regulating features 290 may be 3D printed to provide a desired Poisson's ratio, compressibility, and elastic response.

[0021] Additionally, although a single pressure regulating feature 290 is shown, it is expressly contemplated that feature 290 may be fabricated from multiple layers and / or multiple materials in a layered or conglomerate structure.

[0022] 3A-3B show an abrasive disc attachment assembly having a concentric ring pressure adjustment feature. Figures 3A and 3B show different perspective views of an assembly 300 including a spindle 302, a backup pad 304, and a pressure adjustment feature 350. As shown in Figure 3A, the pressure adjustment feature includes multiple concentric rings. While three rings 310, 320, and 330 are shown in Figure 3A, it is expressly contemplated that in other embodiments, there may be only two rings, or there may be more rings, such as four, five, six, eight, ten, or more rings.

[0023] In one embodiment, as shown in FIG. 3A , each ring 310, 320, 330 occupies an equal portion of the total radius 306, and each has equal radial depths 312, 322, 332 across the pressure adjustment feature 350. The pressure adjustment feature 350 can also be a single component with a gradual or stepped hardness change from the center to the edge of the pad. Using an adhesive layer, a hook-and-loop attachment system, or another suitable attachment system, an abrasive disc can be attached to the surface of the pressure adjustment feature 350 that is remote from the back-up pad 304 in an abrasive application. One advantage of the assembly 300 is that the variation in stiffness or hardness from the center to the edge of the pressure adjustment feature 350 can be adjusted to account for linear velocity variations across the pad, as shown by element 40 in FIG. 1C , providing a uniform cut rate across the pad in an abrasive or polishing application.

[0024] Each of the rings 310, 320, and 330, in one embodiment, differs in their material properties. In one embodiment, the rings have increasing material flexibility with increasing radial distance from the center. Each ring may be made of a different material than adjacent rings such that the flexibility of adjacent rings increases from the center to the outside of the back-up pad.

[0025] This flexibility can be achieved in several ways, such as by selecting a material with a lower hardness (as indicated using any suitable hardness scale, such as Shore D, Shore A, or Shore 00), by selecting a material with a lower elastic modulus, by selecting a material with a higher compressibility (typically quantified by the material's Poisson's ratio), or by modifying the structure of a softer material to contain multiple gas inclusions, such as a foam or sculpted structure. For example, if rings 330 and 320 in assembly 300 comprise materials with hardnesses of 60 and 40 Shore A, respectively (as measured using ASTM D2240), the hardness of ring 310 may be less than 40 Shore A. Note that in some cases, hardness may be best measured using a different scale for pressure regulating feature 350 (e.g., Shore A or Shore 00). In some embodiments, the compressibility of the material used in the pressure regulation feature 350 can be measured via a compression force deflection test per ASTM D3574 when the material is a foam, and via a compression deflection test per ASTM D1056 when the material is a flexible spongy material such as a sponge or an expandable rubber. The material used in the pressure regulation feature 350 can have a modulus of elasticity less than about 650 psi, less than about 500 psi, or optionally less than about 400 psi. The pressure regulation feature 350 can include a material having a compressibility in the range of 10 to 170 psi at 25% deflection. The pressure regulation feature 350 is configured to be elastically deformable, e.g., capable of recovering substantially 100% (e.g., 99% or more, 99.5% or more, or 99.9% or more) to its original state after being deformed. In some embodiments, some materials used in the pressure regulation feature 350 can be compressible (i.e., have a Poisson's ratio less than 0.2 or less than 0.1) to provide the desired deformability. In some embodiments, some materials used in pressure regulating feature 350 may be substantially incompressible, e.g., the relative volume change of the material in response to contact pressure is less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.2%, but still be soft enough to provide the desired deformability.In some embodiments, some materials used for pressure regulation features 350 may be made of substantially incompressible materials that are patterned, 3D printed, embossed, or engraved to provide the desired deformability.

[0026] In some embodiments, pressure regulating feature 350 may include a material having a hardness of less than about 60 Shore A, less than about 40 Shore A, or even less than about 30 Shore A. In some embodiments, the materials used in pressure regulating feature 350 may have a Poisson's ratio of less than about 0.5, less than about 0.4, less than about 0.3, or even less than about 0.2. In some embodiments, some of the materials used in pressure regulating feature 350 may have a negative Poisson's ratio.

[0027] In some embodiments, pressure regulation feature 350 may include one or more of the following materials: foam; a carved, structured, 3D printed, or embossed elastomer; a woven or nonwoven layer; or soft rubber. Suitable foams may be open-cell or closed-cell, including, for example, synthetic or natural foams, thermoformed foams, polyurethane, polyester, polyether, filled or grafted polyether, viscoelastic foam, melamine foam, polyethylene, cross-linked polyethylene, polypropylene, silicone, ionomer foam, etc. Pressure regulation feature 350 may also include foamed elastomers or vulcanized rubbers, including, for example, isoprene, neoprene, polybutadiene, polyisoprene, polychloroprene, nitrile rubber, polyvinyl chloride and nitrile rubber, ethylene-propylene copolymers such as EPDM (ethylene propylene diene monomer), and butyl rubber (e.g., isobutylene-isoprene copolymer). It should be appreciated that the pressure regulating feature 350 may include any suitable compressible structure, such as, for example, a spring, a nonwoven, a woven fabric, an air bladder, etc. In some embodiments, at least a portion of the pressure regulating feature 350 may be 3D printed to provide a desired Poisson's ratio, compressibility, and elastic response.

[0028] The backup pad 304 is substantially harder than the pressure regulation feature 350, i.e., when the assembly 300 is used in a polishing application, the compressive deformation of the backup pad 304 is negligible compared to the compressive deformation of the pressure regulation feature 350. Both components of the backup pad 304 and the pressure regulation feature 350 should be made from suitable durable materials. Example materials for the backup pad 304 include engineering plastics (e.g., nylon, polyphenylene sulfide, polyether ketone, polyether ether ketone, polycarbonate, high density polyethylene, high density polypropylene, polyester, polyurethane, etc.), polymer composites, metals, ceramic composites, and combinations thereof.

[0029] 4A-4C illustrate an abrasive disc mounting assembly having an uneven surface. Assembly 400 includes a spindle 410 that connects to the drive shaft of a power tool or machine. A conical back-up pad 420 is connected to spindle 410 through its flat surface 450. A pressure regulation feature 430 is attached to the conical side of back-up pad 420, on the side opposite surface 450. In one embodiment, the thickness of pressure regulation feature 430 is uniform across the conical back-up pad. The abrasive pad can be attached to surface 440 of pressure regulation feature 430 using an adhesive layer, a hook-and-loop mounting system, or other suitable mounting system for abrasive applications. FIG. 4A illustrates a side view of assembly 400. FIG. 4B illustrates a cutaway view of assembly 400 taken along section line 4B-4B shown in FIG. 4A. FIG. 4C illustrates an exploded view of assembly 400. In one embodiment, the backup pad 420 can be made from a flat component 460 and a conical component 436. The assembly 400 has an overall diameter 402. In some embodiments, the pressure regulation feature 430 has a diameter 432 that is substantially the same length as the diameter 402. However, in some embodiments, the diameter 432 is shorter than the diameter 402. The conical backup pad 420 has a slope 434 that can be adjusted to regulate the contact pressure between a polishing pad mounted on a surface 440 of the pressure regulation feature 430 and a work surface when the polishing pad on the assembly 400 contacts the work surface in a polishing operation. The slope 434 is less than 180°. It can be, for example, about 175°, about 170°, about 165°, about 160°, about 155°, about 150°, about 145°, about 140°, or about 135°. Additionally, the slope can be shallower, for example, between about 176° and 179°.

[0030] In some embodiments, the polishing pad on the mounting assembly 400 initially contacts the work surface at the tip of its conical portion. By more firmly engaging the pad against the work surface, other portions of the polishing pad contact and polish the work surface. In this scenario, the pressure regulation feature 430 is more compressed near the conical tip, and the compression decreases toward the edge of the pad. This results in a contact pressure profile that is greatest at the center of the pad and decreases across the pad toward its edge. This decrease in contact pressure can account for an increase in the linear velocity profile 40 shown in FIG. 1C, which can help the pad remove material more uniformly across the pad from its center to its edge.

[0031] In another embodiment where the goal is to polish a small portion of the work surface, the pad on the mounting assembly 400 provides this ability to contact only the desired area of ​​the work surface without contacting other portions of the work surface. This ability also provides the opportunity to use different locations of the pad to polish the work surface, thereby resulting in a longer life for the polishing pad compared to conventional pad assemblies with flat surfaces that are primarily used from areas near their edges.

[0032] The material used for pressure regulation feature 430 is substantially softer than the material used for conical back-up pad 420; that is, when assembly 400 is used in a polishing application, the compressive deformation of back-up pad 420 is negligible compared to the compressive deformation of pressure regulation feature 430. Flexibility can be achieved in several ways, such as by selecting a material with a lower hardness (as indicated using any suitable hardness scale, such as Shore A or Shore 00), by selecting a material with a lower elastic modulus, by selecting a material with a higher compressibility (typically quantified by the material's Poisson's ratio), or by modifying the structure of a softer material to contain multiple gas inclusions, such as a foam or a sculpted structure. In some embodiments, the compressibility of pressure regulation feature 430 can be measured via a compression force deflection test per ASTM D3574 if the pressure regulation feature is a foam, or via a compression-deflection test per ASTM D1056 if the compressibility is a soft, spongy material, such as a sponge, or an expandable rubber. The pressure regulation feature 430 may have a hardness of less than about 60 Shore A, less than about 50 Shore A, and preferably less than about 40 Shore A. The material used for the pressure regulation feature 430 may have a modulus of elasticity of less than about 400 psi, less than about 300 psi, and preferably less than about 200 psi. The pressure regulation feature 430 may have a compressibility of less than about 75 psi at 25% deflection, optionally less than about 45 psi at 25% deflection. The pressure regulation feature 430 is configured to be elastically deformable, e.g., capable of recovering substantially 100% (e.g., 99% or more, 99.5% or more, or 99.9% or more) to its original state after being deformed. In some embodiments, the pressure regulation feature 430 may be compressible (i.e., have a Poisson's ratio of less than 0.2 or less than 0.1) to provide the desired deformability. In some embodiments, the pressure regulating feature 430 may be substantially incompressible, e.g., the relative volume change of the material in response to contact pressure is less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.2%, but is sufficiently soft to provide the desired deformability.In some embodiments, the pressure regulating feature 430 may be made of a substantially incompressible material that is patterned, 3D printed, embossed, or engraved to provide the desired deformability.

[0033] In some embodiments, pressure regulation feature 430 may include one or more of the following materials: foam; a carved, structured, 3D printed, or embossed elastomer; a woven or nonwoven layer; or soft rubber. Suitable foams may be open-cell or closed-cell, including, for example, synthetic or natural foams, thermoformed foams, polyurethane, polyester, polyether, filled or grafted polyether, viscoelastic foam, melamine foam, polyethylene, cross-linked polyethylene, polypropylene, silicone, ionomer foam, etc. Pressure regulation feature 430 may also include foamed elastomers or vulcanized rubbers, including, for example, isoprene, neoprene, polybutadiene, polyisoprene, polychloroprene, nitrile rubber, polyvinyl chloride and nitrile rubber, ethylene-propylene copolymers such as EPDM (ethylene propylene diene monomer), and butyl rubber (e.g., isobutylene-isoprene copolymer). Suitable foam pressure regulating features 430 may have, for example, a compressibility of less than about 75 psi at 25% deflection, optionally less than about 45 psi at 25% deflection. It should be understood that pressure regulating features 430 may include any suitable compressible structure, such as, for example, a spring, a nonwoven, a woven fabric, an air bladder, etc. In some embodiments, pressure regulating features 430 may be 3D printed to provide a desired Poisson's ratio, compressibility, and elastic response.

[0034] Both components of the back-up pad 420 and the pressure regulation feature 430 should be made from suitable durable materials. Examples of materials for the back-up pad 420 include engineering plastics (e.g., nylon, polyphenylene sulfide, polyether ketone, polyether ether ketone, polycarbonate, high density polyethylene, high density polypropylene, polyester, polyurethane, etc.), polymer composites, metals, ceramic composites, and combinations thereof.

[0035] The embodiments shown in Figures 2-4 are designed to achieve a patterned cut rate that is uniform across the diameter of the back-up pad, thereby improving the overall efficiency and service life of each individual polishing pad attached to the back-up pad. These embodiments also provide a more uniform cut and surface finish on the work surface being polished by them compared to conventional pad assemblies. Each of the embodiments shown in Figures 2-4 is exemplary. It is expressly contemplated that each may be customized depending on the requirements of a given polishing operation. For example, through channels may extend in each embodiment from the surface of the mounting system exposed to the polishing pad to the free surface of the back-up pad to facilitate the extraction and management of debris and dust during polishing. Additionally, each embodiment offers unique advantages.

[0036] 5 illustrates a method for providing a uniform cut rate according to embodiments herein. Method 500 may be useful with any of the abrasive disc mounting assemblies of FIGS. 2-4, or another suitable abrasive disc mounting design.

[0037] At block 510, the abrasive disc mounting assembly I is coupled to a tool. The tool may be a linear sander, rotary sander, orbital sander, random orbital sander, or other suitable tool. The abrasive disc mounting assembly may have another surface structure 506, such as a flat surface 502, a conical surface 504, or a truncated cone, on the side opposite the tool connection side.

[0038] At block 520, the polishing pad is coupled to an abrasive disc mounting assembly that includes a back-up pad coupled to a pressure regulation feature. The polishing pad may be directly coupled to the pressure regulation feature, as shown in block 522, or directly coupled to the back-up pad, as shown in block 524. The polishing pad may also be coupled to the assembly in another suitable manner, as shown in block 526.

[0039] At block 530, a polishing operation is performed, which may include actuating the tool manually as shown in block 527, semi-manually as shown in block 528, or by other suitable methods such as robotically as shown in block 529.

[0040] Figure 6 is a schematic diagram of a robotic paint refinishing system in which embodiments of the present invention are useful. While an example of a paint refinishing robot 604 is shown in Figure 6, it is expressly contemplated that the tool and back-up pad embodiments shown in Figures 2-5 and 8-10 may be used in applications other than paint refinishing.

[0041] 6, each box represents a different hardware component of the system, including a robot controller 602, a robot manipulator 604, and a robotic paint repair stack 606, which includes a compliance force control unit 608, a tool 610, and an abrasive article / compound 612. Data flow is indicated by background arrows 614, starting with a pre-inspection data module 616, which provides inspection data including identified defects in the substrate, and ending with a post-inspection defect data module 618 for processing data generated from the substrate 620 during the defect repair process.

[0042] During operation, the location and characteristics of the defects are provided from the pre-inspection data module 616 to the robot controller 602 that controls the robotic manipulator 604, where a program guides the end effector (stack) 606 to the identified defects to execute some predetermined repair program (deterministic) policy. In some rare cases, the policy may be able to adapt depending on the characteristics of the provided defects.

[0043] For paint repair applications, the robotic paint repair stack 606 includes an abrasive tool 610, an abrasive article and compound 612, along with optional auxiliary equipment such as a (compliance) force control unit 608. As used herein, the robotic paint repair stack 606 is synonymous with the term end effector; however, in this document, the term "stack" refers to an end effector in the context of robotic paint repair. Also, while described with respect to providing robotic paint repair, including primer, paint, and clearcoat repair, it will be understood that the techniques described herein are useful for other industrial applications beyond paint repair.

[0044] The stack 606 of FIG. 6 can provide feedback to the controller 602 in a feedback loop so that the operation of the robot 604, compliance force control unit 608, and tool 610 can continuously adjust settings during the polishing situation.

[0045] 7 shows an exploded view of the components of a robotic paint repair stack. As shown, the robotic paint repair stack 606 includes a robotic arm 700, force control sensors and devices 608, grinding / polishing tools 610, hardware integration devices 702, polishing pads and compounds 612, an engineered polishing process 704, and data and services 706. These elements work together to identify the location of defects and to implement a predetermined repair program using deterministic policies regarding the identified defects, such as the policies discussed in commonly owned and co-pending PCT Application No. PCT / IB2019 / 057053, filed August 21, 2019.

[0046] 8A-8B show a tool for a robotic polishing operation and the corresponding contact pressure profile of the tool against the work surface.

[0047] FIG. 8A shows a tool 800 for a robotic grinding unit. The tool 800 is connected to a rotating device via a vertical shaft 810. An abrasive article is attached to the tool 800 on the surface of a backup pad 820, on the opposite side of the shaft 810. The backup pad 820 is often a flexible pad. FIG. 8B shows a contact pressure profile 850 resulting from the tool being used against a work surface. Even with the flexibility of the pad, the pressure profile 850 of the abrasive on the surface is irregular. Because the pressure is measured from the center of the grinding tool 800, there are pressure spikes from approximately 9 mm from the center to 13 mm at the radius.

[0048] 8A shows a rigid bed design for tool 800, which includes a foam pad that provides flexibility to the abrasive article, attached by adhesive, hook and loop, or mechanically to conform to the surface within the pressure profile of the backing foam. Debris buildup often occurs when tool 800 engages the work surface. This contributes to a lack of pressure uniformity, as well as the tool's characteristics during high-speed abrading.

[0049] 9A-9G illustrate a tool for providing a patterned cutting rate with a robotic repair unit, according to embodiments herein. Figures 9A-9C illustrate an embodiment of a tool that can directly engage a robot, for example, in some embodiments, using a force control unit and / or end effector.

[0050] Handheld power tools require a human user to accommodate the inherent lack of motor precision, however the tool embodiment shown in Figures 9A-9C is useful for robotic units that can leverage the precision and accuracy of automated sharpening tools.

[0051] The tool 900 engages a robotic unit using a shaft 902. The tool has a pad-engagement surface 910 for engaging a pad 904 that engages an abrasive article. The tool surface 910 can be modified to include a pattern of apertures, shown in FIG. 9A as including two sizes of holes 912 and 914. As shown in FIG. 9A, the holes 912, 914 extend through the surface 910. The sets of holes 912, 914 are arranged around the shaft 902, with the smaller holes 912 closer to the shaft than the larger holes 914. In some embodiments, each hole in a given set of holes 912, 914 is equally spaced from adjacent similarly sized holes. Additionally, while circular holes are shown in FIG. 9A, it is expressly contemplated that slats extending partially or completely through the surface 910, indentations extending partially through the surface 910, or other suitable modifications allowing for flexing of the surface 910 are envisioned. Specifically, the design of FIG. 9A allows the tool 800 to flex at a speed and under pressure that facilitates "feathered edges" when paint defects are sanded away so that the surface modification is not easily detectable.

[0052] However, it is specifically contemplated that a given tool design can facilitate certain effects (feathering, cutting edges) and better manage debris generated during the abrasive operation. The goal of managing the cut is to reduce the production of undesirable surface artifacts and improve abrasive disc life and cut consistency.

[0053] FIG. 9B shows an angled tool 920 including a shaft 922 connected to an angled tool surface 930, which allows more force to be applied to the center of the tool 920, weakening the contact points at the outer edges such that the contact weakens as the tool 920 contacts further away from the center of the tool.

[0054] 9C shows a tool 940 having a scalloped edge in addition to the angled surface. However, it is expressly contemplated that in some embodiments the scalloped edge may exist alone without the angled surface. The tool 940 has a shaft 942 that connects to an angled tool surface 950 having a plurality of scallops 952 evenly spaced around the circumference of the tool surface 950. The scallops 952 further differentiate the force from the center to the edge of the tool 940 compared to the tool 920.

[0055] FIG. 9D shows a robotic tool 962 having a foam pad 964 within the assembly 962 .

[0056] Figure 9E shows a flexible tool 972 with a foam pad 974 within the assembly 970. As shown in Figure 9E, the flexible tool has a slope 976 from the spindle to the edge of the tool, with the edge of the tool being thinner than the center of the tool, resulting in additional flexibility at the edge.

[0057] FIG. 9F illustrates a patterned tool 982 having a foam pad 982 within the assembly 980. As shown in FIG. 9F, the tool 982 includes a plurality of indentations 985 extending inward from the outer periphery of the tool 982. The indentations 985 are shown in FIG. 9F as having two edges 988 that meet at a point to form an angle 986. However, it is expressly contemplated that rounded edges and inflection points are possible. The indentations 985 have a depth 987 that extends inward from the circumference of the tool 982. The indentations 985 provide some pressure relief on the outside of the tool assembly 980, thereby allowing for better debris management at the edges. Illustrated in FIG. 9F is an embodiment having four indentations evenly spaced around the circumference of the tool. However, it is expressly contemplated that more or fewer indentations may be appropriate in some embodiments. For example, there may be only two depressions 985, or there may be three depressions 985. Likewise, there may be five, six, seven, eight, ten, twelve, sixteen, twenty or more depressions 985.

[0058] FIG. 9G shows a patterned tool 992 having a foam pad 994 within the assembly 990. The tool 992 includes multiple cutout portions 993 present within the tool 992. As shown in FIG. 9G, the cutout portions extend substantially from the circumference to the spindle radius of the tool 992. The cutout portions may be defined by a length 998 extending perpendicularly from the circumference and a width 997. In some embodiments, the width 997 varies from the circumference to the spindle of the tool 992, e.g., being wider at the circumference than at the spindle. In some embodiments, the cutouts 993 have a curvature 998 at the intersection of the cutouts 993 with the tool spindle. The cutouts 993 provide significant pressure relief for the tool 992, allowing for improved debris management, thermal management, and patterning.

[0059] While Figures 9F and 9G show a flat tool surface extending from the tool spindle, it is expressly contemplated that in other embodiments, recesses 985 or notches 993 may be combined with the slope 976 to provide further flexibility.

[0060] FIG. 10 illustrates a method for providing a patterned cut rate using a robotic polishing system according to embodiments herein. As described above, robotic polishing systems have the ability to polish small areas (e.g., areas less than 35 mm) with fine control. Once the polishing operation is initiated, the robot control unit can adjust grinding parameters to increase the cut rate, cutting efficiency, or improve the aesthetics of the repaired work surface. The tools discussed herein can be used to create patterned cut rates, for example, angled cut rates, in which the tool is angled during the polishing operation to cut deeper at one point of the contact area than at another point. Other cut rate patterns are also contemplated.

[0061] In block 1010, the robotic control cell is started. Starting may include powering the robotic repair unit and moving it to a position so that the abrasive article can engage the work surface. The abrasive article may be urged into contact with the work surface using a powered robotic arm. Pressure may be applied to the abrasive article using a force control unit.

[0062] At block 1020, a polishing operation is performed. In some embodiments, the polishing operation follows a preset repair strategy selected, for example, based on a desired final condition of the engaged work surface. In other embodiments, the polishing operation follows a dynamic strategy to achieve a desired result (e.g., a desired final work surface condition, a desired cut shape, a work surface resistance, etc.).

[0063] At block 1030, feedback is received. For example, feedback may be received from a robot control sensor unit, a servo tool motor sensor unit, and / or a sensor unit embedded directly in the tool. Vibrations may be sensed by a vision system that analyzes the motion of the tool frame by frame during operation.

[0064] At block 1040, tool parameters are modified in-place to allow the polishing operation to continue. In some embodiments, feedback is received and modifications are made without the polishing tool losing contact with the work surface. However, in other embodiments, the tool must be disconnected from the surface so that sensor readings can be captured and feedback can be provided.

[0065] Tool parameters that may be modified in response to received feedback include the contact pressure 1042 between the tool and the work surface, the contact angle 144 of the tool relative to the work surface, or another suitable parameter. For example, the rotational speed may be modified relative to the tool, or the pattern of movement of the tool relative to the work surface, or another suitable parameter.

[0066] The abrasive disc can be attached to the back-up pad and / or damper described herein using any suitable non-permanent attachment feature. For example, in one embodiment, an adhesive can be applied, including a pressure-sensitive adhesive. Hook-and-loop attachment, having either a hook portion or a loop portion on the non-abrasive side of the abrasive disc, can also be used.

[0067] In one embodiment, the abrasive disc is a coated abrasive disc including a backing in which a plurality of abrasive grains are embedded in a make coat and are optionally coated with a size coat and / or supersize coat. The backing substrate can be any of woven fabric, open-weave fabric, knitted fabric, porous fabric, loop material, non-sealed fabric, open-cell or closed-cell foam, nonwoven fabric, spun fiber, film, perforated film, or any other suitable backing material. Fabric backings include cloth (e.g., cloth made from fibers or yarns including polyester, nylon, silk, cotton, and / or rayon, which can be woven, knitted, or stitch-bonded) or scrim. The abrasive grains can include shaped abrasive grains, broken abrasive grains, or plate-shaped abrasive grains. The size of the abrasive grains can be selected based on the aggressiveness of the repair work to be completed. The abrasive disc can be a rigid or flexible abrasive disc.

[0068] The description and illustrations presented above are intended as examples only and are not intended to limit the exemplary embodiments in any manner, except as set forth in the appended claims. It should be noted that the various technical aspects of the various elements of the various exemplary embodiments described above can be combined in numerous other ways, and all of these combinations are considered to be within the scope of the present disclosure.

[0069] Thus, while example embodiments have been disclosed for illustrative purposes, those skilled in the art will recognize that various modifications, additions, and substitutions are possible. Accordingly, the present disclosure is not limited to the above-described embodiments, but can be modified within the scope of the appended claims, along with their full range of equivalents.

[0070] A method for managing contact pressure across an abrasive disc is presented, comprising bonding an abrasive disc to a back-up pad. The back-up pad includes pressure-regulating features that equalize the pressure experienced by the work surface across the radius of the abrasive disc. The method also includes abrading the work surface by contacting the abrasive disc with the work surface. The back-up pad results in an abrasive disc with a substantially uniform cut rate across the surface of the abrasive disc, compared to an abrasive disc on a back-up pad that does not have the pressure-regulating features.

[0071] The method may be performed such that the pressure regulating feature is elastically deformable.

[0072] The method may be practiced such that the pressure regulation feature is disposed between the back-up pad and the abrasive disc.

[0073] The method may be performed such that the pressure regulating feature comprises a material having a hardness of less than about 60 Shore A.

[0074] The method may be performed such that the pressure regulating feature comprises a material having a compressibility of less than about 170 psi at 25% deflection.

[0075] The method may be implemented such that the pressure regulating feature comprises a compressible material.

[0076] The method may be practiced such that the pressure regulating feature comprises a material that is substantially incompressible.

[0077] The method may be practiced such that the pressure regulating feature comprises a patterned, 3D printed, embossed, or engraved substantially incompressible material.

[0078] The method may be implemented such that the pressure regulating feature comprises foam, a carved, structured, 3D printed, or embossed elastomer, a woven layer, a nonwoven layer, or soft rubber.

[0079] The method may be practiced such that the compressible feature is made from multiple layers and / or multiple materials in a layered or conglomerate structure.

[0080] The method may be practiced such that the back-up pad includes a channel for drawing out dust and debris that extends from the surface of the pressure regulation feature on which the abrasive disc is attached to the opposite side of the back-up pad.

[0081] The method may be practiced such that the pressure regulating feature comprises a material having a modulus of elasticity less than about 650 psi.

[0082] The method may be performed such that the pressure regulating feature has a non-uniform thickness.

[0083] The method may be implemented such that the pressure regulating feature comprises a conical cavity mounted on a conical surface of the back-up pad.

[0084] The method may be implemented such that the hardness of the pressure adjusting features varies across the pad from the center of the pad towards the periphery of the pad.

[0085] The method may be implemented such that the hardness of the pressure regulating features varies gradually across the pad.

[0086] The method may be implemented such that the hardness of the pressure regulating features is graduated across the pad.

[0087] The method may be implemented such that the pressure regulating feature includes concentric rings having different hardnesses.

[0088] The method may be implemented such that the hardness of the pressure adjusting features decreases from the center of the pad towards the periphery of the pad.

[0089] The method may be implemented such that the variation in hardness of the pressure regulating features across the pad is proportional to the distance from the center of the pad.

[0090] The method may be performed such that the back-up pad has a non-planar surface and a pressure-regulating feature having a uniform thickness is attached to the surface.

[0091] The method may be practiced such that the non-planar surface of the back-up pad is conical, hemispherical, or dome-shaped.

[0092] The method may be implemented such that a back-up pad in combination with a pressure regulation feature improves debris management of an abrasive disc compared to an abrasive disc on a back-up pad without a pressure regulation feature.

[0093] The method may be implemented such that a back-up pad in combination with a pressure regulating feature improves the thermal management of an abrasive disc compared to an abrasive disc on a back-up pad without a pressure regulating feature.

[0094] The method may be implemented such that a back-up pad in combination with a pressure adjusting feature improves feature mixing of an abrasive disc compared to an abrasive disc on a back-up pad without a pressure adjusting feature.

[0095] A sanding system for causing an abrasive disc to provide a patterned cut rate includes a tool configured to drive the movement of the abrasive disc. The system also includes a back-up pad coupled to the tool. The system also includes pattern features. The pattern features cause the abrasive disc to exhibit the patterned cut rate when the tool is actuated. The patterned cut rate is different from the cut rate exhibited by an abrasive disc attached to a back-up pad and tool that does not have the pattern features.

[0096] The system may be implemented such that the tool is a robotic tool, and the pattern features are integrated into the tool.

[0097] The system may be implemented such that the pattern feature is a back-up pad engaging surface of the tool.

[0098] The system may be implemented such that the pattern features are a plurality of apertures in the back-up pad engaging surface of the tool.

[0099] The system may be implemented such that the plurality of apertures includes a first set of apertures and a second set of apertures.

[0100] The system may be implemented such that the first set of apertures is closer to the edge of the backup engagement surface of the tool than the second set of apertures.

[0101] The system may be implemented such that a first set of apertures has a first radius and a second set of apertures has a second radius, the first radius being larger than the second apertures.

[0102] The system may be implemented so that the aperture extends completely through the back-up pad engaging surface of the tool.

[0103] The system may be implemented such that the pattern feature is a back-up pad engaging portion of a tool coupled to the spindle, the back-up pad engaging portion being perpendicular to the spindle.

[0104] The system may be implemented such that the back-up pad engaging portion has a back-up pad engaging surface having a first diameter and a spindle engaging surface having a second diameter, the first diameter being larger than the second diameter.

[0105] The system may be implemented such that the outer edge of the back-up pad engaging portion is angled from the spindle engaging surface to the back-up pad engaging surface.

[0106] The system may be implemented such that the back-up pad engaging surface includes a scalloped edge.

[0107] The system may be implemented such that the back-up pad engaging portion includes a periphery having a plurality of recesses.

[0108] The system may be implemented such that the recesses are equally spaced around the circumference.

[0109] The system may be implemented such that the pattern features cause a back-up pad engaging portion of the tool to flex during the polishing operation.

[0110] The system may be implemented such that the tool is a spindle configured to engage a power tool.

[0111] The system may be implemented such that the pattern features are coupled to both the tool on the first side and the back-up pad on the second side.

[0112] The system may be implemented such that the pattern feature includes a first portion and a second portion.

[0113] The system may be implemented such that the first portion and the second portion are coplanar and coupled to both the tool and the back-up pad.

[0114] The system may be implemented such that the first portion and the second portion comprise different materials.

[0115] The system may be implemented such that the first and second portions comprise compressible materials.

[0116] The system may be implemented such that the first and second portions comprise an incompressible material.

[0117] The system may be implemented such that the pattern features include compressible conical features.

[0118] The system may be implemented such that the pattern feature is configured to be coupled to the back-up pad on a first side and coupled to the abrasive article on a second side.

[0119] The system may be implemented so that the cutting rate of the system is substantially uniform over a radius extending from the center of the back-up pad to the edge of the back-up pad.

[0120] The system may be implemented such that the cutting rate of the system has a local maximum.

[0121] The system may be implemented such that the cutting rate has at least two maxima.

[0122] The system may be implemented such that the pattern features are elastically deformable.

[0123] The system may be implemented such that the pattern features are disposed between the back-up pad and the abrasive disc.

[0124] The system may be implemented such that the pattern features include a material having a hardness of less than about 60 Shore A.

[0125] The system may be implemented such that the pattern features include a material having a compressibility of less than about 170 psi at 25% deflection.

[0126] The system may be implemented such that the pattern features include material that is patterned, 3D printed, embossed, or engraved, and made from a substantially incompressible material.

[0127] The system may be implemented such that the pattern features include a compressible material.

[0128] The system may be implemented such that the pattern features include one or more of the following materials: foam, carved, structured, 3D printed, or embossed elastomer, woven layer, nonwoven layer, or soft rubber.

[0129] The system may be implemented such that the pattern features are made from multiple layers or materials in a layered or conglomerate structure.

[0130] The system may be implemented such that the back-up pad includes a channel that extends from a surface of the damping feature to an opposite side of the back-up pad.

[0131] The system may be implemented such that the pattern features include a material having a modulus of elasticity less than about 650 psi.

[0132] The system may be implemented such that the pattern features have a non-uniform thickness.

[0133] The system may be implemented such that the pattern feature comprises a conical cavity mounted on a conical surface of the back-up pad.

[0134] The system may be implemented such that the hardness of the pattern features varies across the back-up pad from the center to the periphery.

[0135] The system may be implemented such that the hardness of the pattern features varies gradually across the back-up pad.

[0136] The system may be implemented such that the hardness of the pattern features is graded across the back-up pad.

[0137] The system may be implemented such that the pattern feature comprises a plurality of concentric rings, each concentric ring having a different hardness.

[0138] The system may be implemented such that the hardness of the pattern features decreases from the center to the periphery.

[0139] The system may be implemented such that the variation in hardness of the pattern features is proportional to the distance from the center across the back-up pad.

[0140] The system may be implemented such that the back-up pad has a non-planar surface, and the pattern features are attached to the non-planar surface.

[0141] The system may be implemented so that the non-planar surface of the back-up pad is conical, hemispherical, or dome-shaped.

[0142] A back-up pad for a polishing system is provided that includes a tool engagement feature, an abrasive article engagement feature, and a compressible feature that changes the cut rate profile of an abrasive article attached to the abrasive article engagement feature.

[0143] The back-up pad may be implemented such that the tool engagement feature is on a first side of the back-up pad and the abrasive article engagement feature is on a second side of the back-up pad, the first side being opposite the second side.

[0144] The back-up pad may be implemented such that the compressible features are elastically deformable.

[0145] The back-up pad may be implemented such that the compressible feature is disposed between the back-up pad and the abrasive disc.

[0146] The back-up pad may be implemented such that the compressible feature comprises a material having a hardness of less than about 60 Shore A.

[0147] The back-up pad may be implemented such that the compressible feature comprises a material having a compressibility of less than about 170 psi at 25% deflection.

[0148] The back-up pad may be implemented such that the compressible features include material that is patterned, 3D printed, embossed, or engraved to provide the desired deformability.

[0149] The back-up pad may be implemented such that the compressible feature comprises a material that is compressible.

[0150] The back-up pad may be implemented such that the compressible features include foam, a carved, structured, 3D printed, or embossed elastomer, a woven or nonwoven layer, or soft rubber.

[0151] The back-up pad may be implemented such that the compressible features are made from multiple layers and / or materials in a layered or conglomerate structure.

[0152] The back-up pad may be implemented to include a channel extending from a surface of the damping feature to an opposite side of the back-up pad for the back-up pad to draw out dust and debris.

[0153] The back-up pad may be implemented such that the compressible feature comprises a material having a modulus of elasticity less than about 650 psi.

[0154] The back-up pad may be implemented such that the compressible features have a non-uniform thickness.

[0155] The back-up pad may be implemented such that the compressible feature comprises a conical cavity mounted on a conical surface of the back-up pad.

[0156] The back-up pad may be implemented such that the hardness of the compressible features varies across the pad from the center of the pad to the periphery of the pad.

[0157] The back-up pad may be implemented so that the hardness of the compressible features varies gradually across the pad.

[0158] The back-up pad may be implemented so that the hardness of the compressible features varies gradually across the pad.

[0159] The back-up pad may be implemented such that the compressible features include concentric rings having different hardnesses.

[0160] The back-up pad may be implemented such that the hardness of the compressible features decreases from the center of the pad to the periphery of the pad.

[0161] The back-up pad may be implemented so that the variation in hardness of the compressible features across the pad is proportional to the distance from the center of the pad.

[0162] The back-up pad may be implemented such that the back-up pad has a non-planar surface on which compressible features having a uniform thickness are mounted.

[0163] The back-up pad may be implemented so that the non-planar surface of the back-up pad is conical, hemispherical, or dome-shaped.

[0164] The back-up pad may be implemented such that the back-up pad improves debris management of the abrasive disc compared to an abrasive disc on a back-up pad that does not have compressible features.

[0165] The back-up pad may be implemented such that the back-up pad improves the heat management of the abrasive disc compared to an abrasive disc on a back-up pad that does not have compressible features.

[0166] The back-up pad may be implemented such that the back-up pad in combination with compressible features improves feature mixing of the abrasive disc compared to an abrasive disc on a back-up pad without damping features.

[0167] A spindle for a robotic polishing system includes a tool-engaging shaft. The spindle also includes a back-up pad-engaging surface. The back-up pad-engaging surface includes a pressure adjustment feature that modifies the pressure profile applied by the back-up pad against the work surface.

[0168] The spindle may be implemented such that the tool engagement shaft engages a powered robotic arm.

[0169] The spindle may be implemented as a powered robotic arm including a force control unit.

[0170] The spindle may be implemented such that the controller adjusts the force control unit based on feedback received through the spindle.

[0171] The spindle may be implemented such that the pressure regulation feature includes a plurality of apertures in the back-up pad engaging surface.

[0172] The spindle may be implemented so that a plurality of apertures extend completely through the back-up pad engaging surface.

[0173] The spindle may be implemented so that multiple apertures are coupled to the debris removal tool.

[0174] The spindle may be implemented such that the plurality of apertures includes sets of apertures spaced equidistantly around the tool-engaging shaft.

[0175] The spindle may be implemented so that the sets of apertures are substantially the same size.

[0176] The spindle may be implemented such that the set of apertures is a first set of apertures, and the plurality of apertures includes a second set of apertures.

[0177] The spindle may be implemented such that the second set of apertures has a second radius that is greater than the first radius associated with the first set of apertures.

[0178] The spindle may be implemented such that the back-up pad engagement surface is on a first side of the tool portion that is perpendicular to the tool engagement shaft. The tool portion engages the tool engagement shaft on a second side opposite the first side. A thickness separates the first and second sides.

[0179] The spindle may be implemented with a first side having a first region and a second side having a second region, the second region being smaller than the first region such that an edge connecting the first and second regions forms an angle with the back-up pad engaging surface.

[0180] The spindle may be implemented such that the first region has a periphery that includes a plurality of indentations.

[0181] The spindle may be embodied with a plurality of indentations regularly spaced around its circumference.

[0182] The spindle may be implemented such that the back-up pad engaging surface has a periphery that includes a plurality of indentations.

[0183] The spindle may be embodied with a plurality of indentations regularly spaced around its circumference.

[0184] The spindle may be implemented such that the pressure adjustment feature is elastically deformable.

[0185] The spindle may be implemented such that the pressure regulation feature is disposed between the back-up pad and the abrasive disc. [Example]

[0186] These examples are for illustrative purposes only and are not intended to unduly limit the scope of the appended claims. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques; this is not intended to limit the application of the doctrine of equivalents to the scope of the claims.

[0187] Using a combination of polishing experiments and finite element analysis (FEA) modeling, the performance attributes of the polishing back-up pad described in this disclosure were compared to a typical polishing back-up pad with a flat foam layer of uniform thickness. In each example, the work surface being polished by the polishing pad was planar and parallel to the surface of the abrasive disc used in the experiment. Using commercially available software from Abaqus (SIMULIA™ by Dassault Systemes®), the polishing back-up pad was modeled relative to the work surface in some examples where the attributes of the back-up pad were difficult or impossible to measure experimentally.

[0188] Example 1 In this example, the polishing performance of an abrasive back-up pad described in the present disclosure similar to that shown in FIGS. 2A-2C was evaluated using FEA modeling. FIG. 2E shows an axisymmetric cross-section of the abrasive back-up pad at the working surface of this example. An axisymmetric FEA model was developed in Abaqus with the geometric parameters and material properties listed in Table 1 below. The back-up pad 280 and flat working surface, which are oriented parallel to and in contact with the surface 284 of the abrasive disc 286, are substantially stiffer than the pressure regulation feature 290 in this example. Therefore, to reduce computation time, rigid constraints were applied to the back-up pad 280 and working surface in the FEA model. The working surface was fixed in place as a boundary condition, and a normal displacement load parallel to the centerline 292 was applied to the back-up pad in the FEA model. [Table 1]

[0189] FIG. 11A shows the contact pressure profile between the polishing pad and the work surface, as predicted by the FEA model, with the pad pressed 0.03 inches against the work surface. The contact pressure decreases from the center of the pad toward the edge. FIG. 11B shows the stress contour plot of the deformed polishing backup pad, as predicted by the FEA model, with the pad pressed 0.03 inches against the work surface. As shown, the uniform compression of the pressure-regulating features applies a non-uniform stress across the pressure-regulating features, which is higher near the centerline of the pad and decreases toward the edge of the pad, thereby reducing the contact pressure between the polishing disc and the work surface from the center of the pad to the work surface at its outer edge.

[0190] This polishing pad is K pWhen rotating at an angular velocity of 60 RPM relative to the work surface, where ρ = 1, the empirical Preston equation shown below can be used to determine the material removal rate from the work surface across the surface of the pad [IFW Preston, J. Soc. Glass. Technol., 11, 214, 1927]. Figure 11C shows the variation in material removal (cutting) rate across the surface of the pad. As shown, the material removal rate of the abrasive disc of this example is nearly uniform across the surface of the pad. Material removal rate=K p ×V×P: Preston type K p :Material constants V: linear velocity P: Contact pressure

[0191] Comparative Example 1: In this example, the polishing performance of a typical polishing back-up pad having a uniformly thick foam layer mounted on a flat, rigid back-up pad was evaluated using FEA modeling. Figure 11D shows an axisymmetric FEA model of the polishing back-up pad of this example used to polish a flat work surface, oriented parallel to and in contact with the abrasive disc.

[0192] FIG. 11E shows the contact pressure profile between the polishing pad and the work surface when the pad is pressed 0.03 inches against the work surface as predicted by the FEA model. The contact pressure is uniform across the surface of the pad. FIG. 11F shows the stress contour plot of the deformed polishing back-up pad when the pad is pressed 0.03 inches against the work surface as predicted by the FEA model. As shown, the foam layer deforms uniformly across the pad, creating uniform contact pressure between the polishing disc and the work surface across the pad.

[0193] The uniform contact pressure across the surface of the pad and the increasing linear velocity from the center to the outer edge results in an increasing material removal rate from the center to the outer edge (as shown diagrammatically in FIG. 1C). pThe empirical Preston equation can be used to determine the material removal rate from the work surface across the surface of the pad when rotating at an angular velocity of 60 RPM relative to the work surface, where ρ = 1. Figure 11G shows the variation in material removal (cutting) rate across the pad.

[0194] Comparing Figures 11C and 11G, it can be concluded that the polishing pad of Figure 2E applies a much more uniform cut rate to the work surface across the surface of the pad. Comparing the areas under these curves, which represent the total amount of cut from the work surface, it can be observed that the pad of Figure 2E removes more material from the work surface compared to a typical polishing pad.

[0195] Example 2: In this example, the polishing performance of an abrasive back-up pad similar to the pad shown in Figures 2A-2C was evaluated. A 5-inch diameter pad was experimentally fabricated to test the pad concepts of this disclosure. The pad had a metallic conical back-up pad with a spindle fabricated from 6061 aluminum and a pressure-regulating feature fabricated from a multi-layer foam block with a conical cavity with the same profile as the conical back-up pad. The foam block with the cavity was fabricated from 20 layers of 3M™ Cushion-Mount™ Plus Plate Mounting Tape E1060H (a 0.06-inch thick double-coated foam tape). The pad was fabricated as follows: Using a laser cutter, 20 circular disks with an outer diameter of 5 inches were cut from the above Mounting Tape e. Using the same laser cutting machine, circular holes of the appropriate diameter were cut out of 16 of the 20 Mounting Tape discs, and a conical cavity with a profile similar to the conical backup pad was created by stacking these 16 ring layers. The four remaining intact Mounting Tape discs were stacked together and the stack laminate was then glued to the bottom of the foam stack with the cavity. At this point, we had a pressure control feature with a central cavity. A layer of 3 mil thick double-sided Scotch VHB tape was adhered to the entire surface of the conical side of the metal backup pad. The pressure regulation feature was attached from its hollow side onto the VHB tape on a metal cone back-up pad. A 3M NX Disc Coated Aluminum Oxide Disc - Very Fine Grade - P180 Grit (5 inch diameter) 31217 was adhered with its PSA side to the flat surface of the pressure control feature on the prepared pad.

[0196] Figures 12A-12D show polishing pad articles made according to the above-described process. Figure 12A shows a metal cone backup pad with a spindle. Figure 12B shows a pressure regulation feature made of a multi-layer foam block structure. Figure 12C shows a polishing pad assembly with an abrasive disc attached to the free surface of the pressure regulation feature, and Figure 12D shows a cutaway view taken along section line 12D-12D shown in Figure 12C.

[0197] Example 2 Wear test The test method involved loading an abrasive pad into a drilling press. The drilling press was obtained from McMaster-Carr (Part Number: 2799A21, which is an Economy Benchtop drilling press with 120 V AC and a 13-1 / 4 inch maximum work surface diameter). The drilling press drives the abrasive pad into a work surface secured on a typical workbench table chuck. Material from the work surface is removed during the drilling process. The specific steps of the test procedure are as follows: 1. Place the work surface, a 6" x 6" flat sheet of 0.5" thick MIC 6 cast aluminum (polished 6061 aluminum), on the drill press table. Secure the work surface to the drill press table via two "C-clamps." 2. Set the RPM (800 rpm) and test duration (1 minute) on the drill press. 3. Turn on the drill and engage the abrasive on the top of the work surface under a fixed, given load (5 lbs). 4. Remove and clean the work surface. After removing the polished work surface from the drill table, the work surface was cleaned with a blast of air from a high-pressure nozzle (100 psi). A hand towel containing water and IPA was then used to clean the work surface of polished surface dust. 5. Place the machined surface in a Nanovea HS2000 3D non-contact surface profilometer and measure the cut profile on the polished machined surface.

[0198] 12E shows the cut profile of a work surface polished with the polishing pad shown in FIGS. 12A-12D using the test procedure described above. As shown, a uniform cut was applied to the work surface across the polishing pad.

[0199] Comparative Example 2: In this example, the polishing performance of a typical polishing back-up pad currently used in polishing processes, which has a uniformly thick foam block mounted on a flat back-up pad, was experimentally evaluated. A 5-inch diameter pad was fabricated using the same construction materials as used in Example 2. The pad had a flat metal back-up pad with a spindle fabricated from 6061 aluminum and a flat multi-layer foam block mounted on the flat surface of the metal back-up pad. The foam block was fabricated from seven layers of 3M™ Cushion-Mount™ Plus Plate Mounting Tape E1060H. The steps for fabricating this pad were as follows: Using a laser cutter, seven circular disks with an outer diameter of 5 inches were cut from the above mounting tape. All the circular discs made in the previous step were stacked on top of each other to make a cylindrical foam block. A layer of 3 mil thick double-sided Scotch VHB tape was adhered to the entire flat surface of the metal back-up pad. The foam block was mounted face up on the VHB tape on a flat back-up pad. A 3M NX Disc Coated Aluminum Oxide Disc - Very Fine Grade - P180 Grit (5 inch diameter) 31217 was adhered to the flat surface of the multi-layer foam block of the prepared pad, with its PSA side facing away from the metal back-up pad.

[0200] The resulting structure is shown in Figures 12F-12I. The flat back-up pad is shown in Figure 12F, the multilayer foam block is shown in Figure 12G, and the entire assembly is shown in Figure 12H. Figure 12I shows a cutaway view of the assembly in 12H along section line 12I-12I. The polishing performance of the polishing pads of this example was evaluated using the same wear testing procedure as described in the wear testing of Example 2 above.

[0201] The resulting cut profile of polishing pad 12F is shown in Figure 12J. As shown, a non-uniform cut was applied to the work surface across the polishing pad, increasing from the center of the pad toward its edge.

[0202] Example 3 In this example, the polishing performance of a polishing back-up pad having a concentric ring pressure adjustment feature similar to that shown in Figures 3A and 3B of the present disclosure was experimentally evaluated. To test this pad concept in the present disclosure, a 5-inch diameter pad was fabricated. The pad had a metal flat back-up pad with a spindle fabricated from 6061 aluminum, as shown in Figure 12F, and a pressure adjustment feature fabricated from three rings, as shown in Figure 3A. The pad was fabricated as follows. Using a laser cutter, two circular disks with an outer diameter of 1.666 inches were cut from Resilient Polyurethane Foam Sheet-Soft (0.25 inch thick, 11 psi pressure to compress 25%) (part number: 86375K134) obtained from McMaster-Carr. A layer of 3 mil thick double-sided Scotch VHB tape was used to laminate the two circular disks created in the previous step together. This laminate was used as the center of the pressure control feature in the pad. Using the same laser cutter, a circular ring with an inner diameter of 1.666 inches and an outer diameter of 3.333 inches was cut from Resilient Polyurethane Foam Sheet - Ultra Soft (0.5 inch thick, 3 psi pressure to compress 25%) (Part Number: 86375K114) obtained from McMaster-Carr. This ring was used as the middle concentric ring of the pressure control feature in the pad. Using the same laser cutter, another circular ring with an inner diameter of 3.333 inches and an outer diameter of 5 inches was cut from a Super-Cushioning Polyurethane Foam Circle (0.5 inch thick, 0.3 psi pressure to compress 25%) (part number: 8883K54) obtained from McMaster-Carr. This ring was used as the outer concentric ring of the pressure control feature in the pad. A layer of 3 mil thick double-sided Scotch VHB tape was adhered to the entire flat surface of the metal back-up pad. The circular laminate and the two concentric rings produced in the previous step were mounted on their faces onto VHB tape on a flat back-up pad. A 3M NX Disc Coated Aluminum Oxide Disc - Very Fine Grade - P180 Grit (5 inch diameter) 31217 was adhered to the flat surface of the concentric ring pressure adjusting feature of the prepared pad, from its PSA side away from the metal back-up pad. The pressure regulation feature was attached from its hollow side onto the VHB tape on a metal cone back-up pad. A 3M NX Disc Coated Aluminum Oxide Disc - Very Fine Grade - P180 Grit (5 inch diameter) 31217 was adhered with its PSA side to the flat surface of the pressure control feature on the prepared pad.

[0203] The polishing performance of the polishing pad of this example was evaluated using the same wear test procedure as described in the wear test of Example 2 above. The resulting cut profile of the polishing pad of this example is shown in Figure 13A. As shown, a non-uniform cut pattern was applied to the work surface across the polishing pad. As shown in Figure 12J, using a typical polishing pad with a flat foam layer, the center of the polishing pad removed the most material from the work surface, while the outer parts of the polishing pad removed the least material, due to the increase in linear velocity toward the edge of the pad, which increases the cut rate from the center of the pad toward its edge.

[0204] Next, an FEA model of the polishing pad of this example was developed for a flat work surface placed parallel to the surface of the abrasive disc. The same geometric shapes were used for the metal backup pad, central foam disc, and concentric rings of pressure regulation features. Elastic moduli of 11, 3, and 0.3 psi and Poisson's ratios of 0.4, 0.1, and 0.1, respectively, were used for the material properties of the central disc, middle, and other concentric rings in the FEA model. Rigid body constraints were applied to the metal backup pad and work surface, which are substantially stiffer than the pressure regulation features, thereby reducing calculation time. A 5-pound compressive load was applied to the backup pad spindle against the work surface while the work surface was fixed in place. Figure 13B shows the FEA-predicted contact pressure profile between the polishing pad and work surface. As shown, the contact pressure was substantially greater in the central region of the disc above the central disc of the pressure regulation features and decreased toward the edge of the abrasive disc. The reason behind this contact pressure profile is the distribution of hardness of the material used in the pressure regulating features, which causes significantly higher compressive stresses in the central region of the disc than in the regions above the concentric rings, as shown in FIG. 13C.

[0205] The materials used to make the pads in this example were chosen arbitrarily simply to demonstrate the effect that varying the hardness of the pressure regulating features across the pad has on the pad's cut rate performance. However, by adjusting the number of concentric rings and their hardness across the pad, the cutting pattern can be adjusted to obtain a desired cutting profile across the pad.

[0206] Example 4 In this example, the polishing performance of an abrasive back-up pad having a non-uniform surface similar to that shown in Figures 14A-14C of the present disclosure was experimentally evaluated. To test this pad concept in the present disclosure, a 5-inch diameter pad was fabricated. The pad had a metal back-up pad including a conical surface on one side and a flat surface with a spindle fabricated from 6061 aluminum on the other side, like the back-up pad shown in Figure 14A, and a pressure regulating feature fabricated from a foam layer having a uniform thickness of 0.5 inches. The pad was fabricated as follows. A laser cutter was used to cut circular disks with an outer diameter of 5 inches from Resilient Polyurethane Foam Sheet-Ultra Soft (0.5 inch thick, 3 psi pressure to compress 25%) (part number: 86375K114) obtained from McMaster-Carr. A layer of 3 mil thick double-sided Scotch VHB tape was adhered to the entire conical surface of the metal back-up pad. The circular foam disk made in the previous step was attached, face up, onto the VHB tape on the conical back-up pad. A 3M NX Disc Coated Aluminum Oxide Disc - Very Fine Grade - P180 Grit (5 inch diameter) 31217 was adhered to the free surface of the pressure control feature of the prepared pad, with its PSA side facing away from the metal back-up pad.

[0207] The polishing performance of the polishing pad of this example was evaluated using the same wear test procedure as described in the wear test of Example 2 above. The resulting cut profile of the polishing pad of this example is shown in Figure 14D. As shown, a uniform cut pattern was applied to the work surface across the polishing pad. By engaging the polishing pad against the work surface, the central region of the polishing pad closer to the work surface first contacted the work surface, and the central region of the pressure-regulating feature was compressed, forcing other regions on the polishing disc into contact with the work surface. Therefore, the central region of the polishing disc contacted the work surface for a longer period of time during the polishing process, resulting in higher material removal from the region closer to the center of the pad. In addition, the central region of the pad experienced more compression due to the densification of the foam layer, making this region harder than other regions of the pad. This caused a higher contact pressure under the central region of the pad, reducing the contact pressure profile toward the edge of the pad, which in turn compensated for the increased linear velocity of the pad toward the edge of the pad. As a result, the pad removed material uniformly from the work surface across the pad.

Claims

1. 1. A method for managing contact pressure across an abrasive disc, comprising: coupling the abrasive disc to a back-up pad having pressure regulation features that equalize the pressure experienced by a work surface across a radius of the abrasive disc; abrading the work surface by contacting the abrasive disc with the work surface; The method of claim 1, wherein the hardness of the pressure adjusting feature decreases across the back-up pad from the center of the back-up pad to the periphery of the back-up pad, whereby the back-up pad provides the abrasive disc with a cut rate that is substantially uniform across the surface of the abrasive disc compared to the abrasive disc on a back-up pad that does not have a pressure adjusting feature.

2. The method of claim 1 , wherein the pressure regulating feature is elastically deformable.

3. The method of claim 1 , wherein the pressure regulating feature is made from multiple layers or materials in a layered or conglomerate structure.

4. The method of claim 1, wherein the backup pad has a conical shaped portion and the pressure adjustment feature, and the pressure adjustment feature has a conical cavity shape that engages with the conical shaped portion.

5. 1. A back-up pad for a polishing system, comprising: a tool engagement feature for engaging a spindle included in the polishing system; an abrasive article engagement feature for engaging an abrasive article; a compressible feature that changes the cut rate profile of the abrasive article attached to the abrasive article engagement feature; A back-up pad, wherein the compressible features have a hardness that decreases across the back-up pad from the center of the back-up pad to the periphery of the back-up pad.

6. The back-up pad of claim 5 , wherein the compressible feature is elastically deformable.

7. 6. The back-up pad of claim 5, wherein the compressible features comprise a material that is patterned, 3D printed, embossed, or engraved to provide a desired deformability.

8. The back-up pad of claim 5 , wherein the compressible feature is made from multiple layers and / or materials in a layered or conglomerate structure.

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