Patent Application
20200316751
The present disclosure relates generally to systems and methods of machining metallic workpieces and, more specifically, to a metal-bonded grinding wheel and related methods of processing thereof.
Many known metallic workpieces have grooves or channels formed therein with a machining tool. The machining tool includes a rotatable shaft and a grinding wheel coupled to the shaft. At least some known grinding wheels are fabricated from a metallic substrate that is coated with a layer of abrasive material. For example, the metallic substrate may be initially coupled on a first shaft in a plating vessel to enable the layer of abrasive material to be cured on the surface of the metallic substrate. The grinding wheel is then uncoupled from the first shaft and coupled on a second shaft within a truing and dressing machine which shapes the grinding wheel to achieve a final profile in a precise and accurate manner. The grinding wheel is then uncoupled from the second shaft and coupled on an arbor in an arbor-mounting machine. The process of coupling and uncoupling the grinding wheel from the shafts within the different machines may be time-consuming, and any deformations or dimensional inaccuracies resulting therefrom facilitate increasing the likelihood of runout of the final rotating arbor-grinding wheel assembly. In addition, generally, known grinding wheels have a relatively short and limited lifespan, which also increases the cost and time needed to perform a machining operation.
In one aspect, a method of processing a rotatable assembly is provided. The method includes mounting a grinding wheel on an arbor to form the rotatable assembly. The grinding wheel includes a ring-structure formed from a plurality of grit particles dispersed within a metallic material. The method also includes mounting the rotatable assembly within at least one dressing machine, wherein the rotatable assembly is rotatable relative to a dressing tool within the at least one dressing machine, and shaping the grinding wheel with the dressing tool to define a final outer profile of the grinding wheel configured to machine a workpiece.
In another aspect, a method of processing a grinding wheel is provided. The method includes mounting a rotatable assembly within at least one dressing machine. The grinding wheel includes a ring-structure, wherein the rotatable assembly is rotatable relative to a dressing tool within the at least one dressing machine. The method also includes channeling a stream of fluid between the grinding wheel and the dressing tool, moving the dressing tool towards the grinding wheel, and using an acoustic sensor to determine when contact is achieved between the dressing tool and the grinding wheel.
In yet another aspect, a system for use in shaping a grinding wheel is provided. The system includes at least one dressing machine including a dressing tool, and a rotatable assembly mounted within the at least one dressing machine. The rotatable assembly includes an arbor, and a grinding wheel coupled to the arbor. The grinding wheel includes a ring-structure formed from a plurality of grit particles dispersed within a metallic material.
The embodiments described herein relate generally to metal-bonded grinding wheel and related methods of processing thereof. In one embodiment, the grinding wheel described herein is mounted on an arbor with a set of gears and bearings to form a dressing assembly. After mounted, the grinding wheel on the dressing assembly is dressed with the gears and bearings already installed to facilitate increasing the stability of the dressing assembly during the dressing processes. As a result, the surface finish of the grinding wheel is facilitated to be enhanced. The grinding wheel may then be removed from the dressing assembly and subsequently installed within a groove grinding machine.
In another embodiment, the grinding wheel described herein is mounted on an arbor to form a grinding assembly. After mounted, the grinding assembly is dressed (e.g., trued and conditioned) in different machines all while remaining mounted to the same arbor. Mounting the grinding wheel on the arbor prior to dressing facilitates reducing rotational runout as compared to known dressing processes that require the grinding wheel be coupled to, and uncoupled from, a variety of different shafts in different processing machines. Dressing the grinding wheel facilitates defining a final outer profile, such that the second grinding assembly is ready for immediate use when transferred as a unitary and fully-assembled structure. In addition, in either embodiment, the grinding wheel is a ring-structure formed from a plurality of grit particles dispersed within a volume of metallic material. As such, the grinding wheel may be reconditioned to facilitate increasing its useful service life.
In the exemplary embodiment, a first process step 116 includes mounting assemblies 100 or 115 within at least one dressing machine 118. For example, dressing machine 118 may be, but is not limited to, a truing machine 120. Truing machine 120 includes a first dressing tool 122, such as an electrical discharge machining tool, and assemblies 100 or 115 are rotatable relative to first dressing tool 122 within truing machine 120 to facilitate shaping an outer surface 124 of grinding wheel 106 to define an intermediate outer profile. A second process step 126 includes removing assemblies 100 or 115 from truing machine 120 and mounting assemblies 100 or 115 within a conditioning machine 128 that includes a second dressing tool 130, such as a conditioning wheel. Assemblies 100 or 115 are rotatable relative to second dressing tool 130 to facilitate shaping outer surface 124 such that a final outer profile is defined, as will be explained in more detail below. In an alternative embodiment, truing and conditioning of grinding wheel 106 is performed in the same dressing machine 118 that includes both first dressing tool 122 and second dressing tool 130.
In the exemplary embodiment, a third process step 132 includes removing assemblies 100 or 115 from conditioning machine 128 and coupling grinding wheel 106 to a groove grinding machine 134. In one embodiment, gear and bearing system 104 and grinding wheel 106 are removed from arbor 102 (shown in
In operation, grinding wheel 106 is rotated by groove grinding machine 134 to enable a workpiece 136 to be machined. Thus, third process step 132 also includes machining a feature 138, such as a groove, into workpiece 136 with grinding wheel 106. As noted above, outer surface 124 of grinding wheel 106 has a final outer profile defined when processed by conditioning machine 128. More specifically, because the final outer profile is defined, feature 138 may be formed with a dimensional tolerance that is within a predefined range. The profile of outer surface 124 changes as material is abraded therefrom as machining processes are performed with grinding wheel 106. In the exemplary embodiment, the first and second process steps 116 and 126 may be repeated on assemblies 100 or 115 after grinding wheel 106 has been worn to a degree where it can no longer form feature 138 with a dimensional tolerance that is within the predefined range.
Grinding wheel 106 may be fabricated from any material, or in any manner, that enables assemblies 100 or 115 to function as described herein. For example, grinding wheel 106 may be fabricated in a manner that facilitates reconditioning and reuse of grinding wheel 106, as described above. For example, in the exemplary embodiment, grinding wheel 106 includes a ring-structure formed from a plurality of grit particles 140 dispersed within a metallic material 142. In one embodiment, grinding wheel 106 is fully formed from the combined mixture of grit particles 140 and metallic material 142. In an alternative embodiment, the combined mixture may be formed on a substrate such that only an outer radial portion of grinding wheel 106 is formed from the combined mixture. In such an embodiment, grit particles 140 are continuously exposed along outer surface 124 of grinding wheel 106 as outer surface 124 is abraded during use. In addition, dispersing grit particles 140 within metallic material 142 enables outer surface 124 to be reconditioned and re-shaped as necessary to enable the final outer profile to be redefined for use in machining workpiece 136. In one embodiment, grit particles 140 may include, but are not limited to, a cubic boron nitride material. Metallic material 142 may include, but is not limited to, a bronze alloy material.
In the exemplary embodiment, referring to
Second dressing tool 130 is then moved along z-axis 148 towards grinding wheel 106 to enable a first registration point 156 to be defined on a first side 158 of grinding wheel 106. For example, first registration point 156 is defined as a location between second dressing tool 130 and first side 158 of grinding wheel 106 where contact therebetween is first initiated. Referring to
In some embodiments, grinding wheel 106 is used to machine a feature into a test coupon (not shown) before machining workpiece 136 (shown in
In the exemplary embodiment, nozzle 146 channels a stream 166 of fluid between grinding wheel 106 and second dressing tool 130, and an acoustic sensor 144 is used to determine when contact is achieved between second dressing tool 130 and grinding wheel 106. For example, stream 166 of fluid facilitates providing an audible communication path between acoustic sensor 144 and the interface defined between second dressing tool 130 and grinding wheel 106. Positioning acoustic sensor 144 a distance from the interface enables conditioning machine 128 to compensate for the effects of thermal expansion, for example, in components within machine 128. When contact is achieved therebetween, an acoustic signal is transmitted through the audible communication path and received at acoustic sensor 144. Acoustic sensor 144 fine-tunes the acoustic signal to remove noise, and to select different frequency and decibel levels indicative of contact being achieved.
The embodiments described herein relate to systems and methods of processing a grinding wheel that facilitates reducing runout of a rotating assembly, that facilitates calibrating a dressing machine in a simplified and efficient manner, and that also enables the use of the grinding wheel fully formed from a mixture of grit particles and metallic material. The systems and methods described herein accomplish the aforementioned objectives by either installing a gear and bearing system and the grinding wheel on an arbor before performing the processing, or dressing the grinding wheel and using the grinding wheel to machine a workpiece all while mounted on the same arbor. In such an embodiment, the surface finish of the grinding wheel is enhanced and the grinding assembly is ready for immediate use after the conditioning process is complete.
Exemplary embodiments of dressing and grinding assemblies, and related methods of processing, are described above in detail. Although the systems herein described and illustrated in association with a rotatable grinding wheel, the invention is also intended for use with any rotatable machining tool. Moreover, it should also be noted that the components of the invention are not limited to the specific embodiments described herein, but rather, aspects of each component may be utilized independently and separately from other components and methods of assembly described herein.
This written description uses examples to disclose various embodiments, including the best mode, and also to enable any person skilled in the art to practice the various implementations, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
