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US 6,411,861 B1Granted
Method and apparatus for grinding composite workpieces
AssigneeUnova U.K. Limited
InventorsStuart Clewes, John David Pickles
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AssigneeUnova U.K. Limited
InventorsStuart Clewes, John David Pickles
Estimating the term…
A method is described for grinding a composite workpiece to form a component having concentric and eccentric cylindrical regions. The method comprises mounting the workpiece in a computer controlled grinding machine having a grinding wheel the advance and withdrawal of which is controllable by a program entered into the controlling computer, loading a wheelfeed controlling program into the computer, relatively positioning the grinding wheel and the workpiece to align the wheel with a first selected region of the workpiece, advancing the grinding wheel towards the selected region so as to grind the surface thereof, controlling the wheelfeed so as to maintain grinding contact between the grinding wheel and the workpiece so as either to grind a concentric cylindrical region thereon or an offset cylindrical region thereon as required, information about each selected region of the workpiece being stored in the computer and addressed as appropriate so that the wheelfeed can be controlled appropriately depending on whether a selected workpiece region is to be ground as a concentric or an offset cylindrical region. The method allows a workpiece having both concentric and offset cylindrical regions thereon to be ground using a single grinding machine under computer control without demounting the workpiece from the machine. A computer controlled grinding machine is described as are programs for controlling the machine.
A method of grinding a composite workpiece to form a component having concentric and eccentric cylindrical regions, comprising, mounting the workpiece for rotation about a primary axis in a computer controlled grinding machine, the grinding machine having a grinding wheel the advance and withdrawal of which is controllable by a program entered into the machine controlling computer, loading wheelfeed controlling program into the computer, positioning the grinding wheel relative to the workpiece, or the workpiece relative to the grinding wheel, so that the wheel is aligned with a first selected region of the workpiece, advancing the grinding wheel towards the selected region so as to grind the surface thereof, controlling a wheelfeed so as to maintain grinding contact between the grinding wheel and the workpiece so as either to grind a concentric cylindrical region thereon or an eccentric offset cylindrical region thereon as required, information about each selected region of the workpiece being stored in the computer and addressed as appropriate so that the wheelfeed can be controlled appropriately depending on whether a selected workpiece region is to be ground as a concentric or an eccentric offset cylindrical region, in which the wheelfeed controlling program is programmed so as to be able to distinguish between concentric and eccentric regions of a workpiece from workpiece data stored therein to enable the wheelfeed to be controlled accordingly so as to grind as required a cylindrical surface concentric with a primary axis of the workpiece or a cylindrical surface which is eccentric thereto, whose axis is spaced from but parallel to the said primary axis, and which is also programmed to introduce small advance and retract movements in the wheelfeed while the grinding wheel is engaged in grinding a concentric cylindrical workpiece region so as to introduce into the ground region an opposing eccentricity in the cylindrical surface which is equal and opposite to any eccentricity which grinding process forces introduce into the ground region, so that the two eccentricities cancel out.
A method of grinding a workpiece having both concentric and eccentric offset cylindrical regions thereon using a single grinding machine under computer control without demounting the workpiece from the machine, in which the computer is loaded with data about the workpiece, how different regions are to be ground, and wheelfeed instructions, and the grinding process is adjusted for each region as detailed by the workpiece and region data stored in the computer, thereby enabling a workpiece to be left in place between centers while different regions therealong are ground to form cylindrical surfaces some of which are concentric with a primary axis of rotation of the workpiece and others of which are eccentric offset thereto, in which control is programmed so as to be able to distinguish between concentric and eccentric regions of a workpiece from workpiece data stored therein to enable a wheelfeed to be controlled accordingly so as to grind as required a cylindrical surface concentric with a primary axis of the workpiece or a cylindrical surface which is eccentric thereto, whose axis is spaced from but parallel to the said primary axis, and which is also programmed to introduce small advance and retract movements in the wheelfeed while a grinding wheel is engaged in grinding a concentric cylindrical workpiece region so as to introduce into the ground region an opposing eccentricity in the cylindrical surface which is equal and opposite to any eccentricity which grinding process forces introduce into the ground region, so that the two eccentricities cancel out.
A computer controlled grinding machine for grinding a composite workpiece comprising a grinding wheel, drive means for rotating the wheel, wheelfeed drive means for advancing and withdrawing the grinding wheel towards and away from a workpiece region in a precise manner, computer means for controlling the wheelfeed drive means, which computer means includes memory means for storing programmable wheelfeed instructions whereby the position of the wheel at each instant during a grinding process can be controlled, program means loaded into the computer to control the wheelfeed drive and the position of the grinding wheel, or the workpiece, so as to control, at selected regions along the workpiece, the advance and withdrawal of the grinding wheel before during and after grinding each said region, so that eccentric and concentric cylindrical grinding of different workpiece regions may be performed without demounting the workpiece, wherein the grinding process introduces unwanted eccentricity into concentrically ground cylindrical workpiece surfaces of the composite workpiece, and the computer means includes memory means for storing corrected wheelfeed program instructions or signals for use during the grinding of such regions.
A method of setting up a computer controlled grinding machine for grinding concentric and eccentric cylindrical regions of an elongate composite workpiece, the workpiece being supported at its opposite ends for grinding thereof, in which axial variations in unwanted eccentricity introduced by the grinding process are taken into account, such that regions towards the center of the workpiece tend to require a greater degree of eccentricity compensation than do those adjacent said opposite ends, said method comprising the steps of advancing a grinding wheel towards a selected region so as to selectively grind either a concentric or an eccentric cylindrical region thereon as required, cylindrically grinding all of said concentric cylindrical regions of the workpiece without introducing any compensation for unwanted process-induced eccentricity, thereafter making measurements on the workpiece to determine the extent and angular position of any unwanted eccentricity for each of the ground regions, and separately adjusting wheelfeed program instructions or control signals to be used to control wheelfeed during subsequent grinding of each said concentric or eccentric region of the same or similar workpieces, so as to compensate individually for each said region for any process-induced eccentricity.
A method of grinding cylindrical surfaces of a crankshaft having concentric and eccentric cylindrical regions which uses a software controlled crankpin following facility incorporated into a computer controlled grinding machine to permit a grinding wheel to follow the relatively excessive eccentric movement of the crankpins of the crankshaft during the grinding of the crankshaft as the crankshaft rotates, and which at a smaller scale introduces a complementary eccentricity for removing unwanted eccentricity introduced into the concentric cylindrically ground surfaces of the crankshaft as a consequence of grinding process forces exerted as such surfaces are ground, and which tends to appear after the crankshaft is stress relieved, so as to cancel out the grinding process induced eccentricity.
A method of operating a computer controlled grinding machine to grind a composite workpiece, using a grinding wheel so as to eccentrically grind a region of the workpiece which is to have a concentric cylindrical surface relative to the workpiece primary axis after grinding, rather than concentrically grinding the said region, the degree of eccentricity being such that when the ground workpiece is stress relieved after grinding, the region will be concentric relative to the primary axis of the workpiece, and wherein a similar computer control of wheelfeed albeit at a larger scale is employed to allow eccentric offset cylindrical surfaces of the workpiece also to be ground, using said wheel on the grinding machine.
Composite workpieces when made in accordance with the method of grinding a composite workpiece to form a component having concentric and eccentric cylindrical regions, comprising, mounting the workpiece for rotation about a primary axis in a computer controlled grinding machine, the grinding machine having a grinding wheel the advance and withdrawal of which is controllable by a program entered into the machine controlling computer, loading a wheelfeed controlling program into the computer, positioning the grinding wheel relative to the workpiece, or the workpiece relative to the grinding wheel, so that the wheel is aligned with a first selected region of the workpiece, advancing the grinding wheel towards the selected region so as to grind the surface thereof, controlling a wheelfeed so as to maintain grinding contact between the grinding wheel and the workpiece so as either to grind a concentric cylindrical region thereon or an eccentric offset cylindrical region thereon as required, information about each selected region of the workpiece being stored in the computer and addressed as appropriate so that the wheelfeed can be controlled appropriately depending on whether a selected workpiece region is to be ground as a concentric or an eccentric offset cylindrical region, in which the wheelfeed controlling program is programmed so as to be able to distinguish between concentric and eccentric regions of a workpiece from workpiece data stored therein to enable the wheelfeed to be controlled accordingly so as to grind as required a cylindrical surface concentric with a primary axis of the workpiece or a cylindrical surface which is eccentric thereto, whose axis is spaced from but parallel to the said primary axis, and which is also programmed to introduce small advance and retract movements in the wheelfeed while the grinding wheel is engaged in grinding a concentric cylindrical workpiece region so as to introduce into the ground region an opposing eccentricity in the cylindrical surface which is equal and opposite to any eccentricity which grinding process forces introduce into the ground region, so that the two eccentricities cancel out.
A computer program for setting up a computer controlled grinding machine to set up wheelfeed instructions to control the grinding of composite workpieces comprising the following steps:
A computer program for setting up and operating a computer controlled grinding machine to grind similar composite workpieces with eccentricity correction of concentrically ground regions, comprising the steps of:
Dependencies are inferred from the claim text.