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US 6,319,097 B1Granted
Grinding methods and apparatus
AssigneeUnova U.K. Limited
InventorsStephen Roger Coverdale, Michael Laycock
Life of this patent
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AssigneeUnova U.K. Limited
InventorsStephen Roger Coverdale, Michael Laycock
Estimating the term…
The time to grind a workpiece can be reduced by selecting a grinding wheel whose width is not substantially greater than wheel strength considerations require, and which may therefore be less than the axial length of the region to be ground providing a work rest or work steady to increase the workpiece stiffness if required, and performing a succession of plunge grinding steps so as to grind the whole of the said axial region. Typically the grinding wheel is an electroplated CBN wheel, and the width of the grinding wheel selected is the narrowest permissible given the desired feed rate and motive power available. A grinding machine is disclosed comprising a wheelhead having mounted thereon a grinding wheel whose width is not substantially greater than that dictated by structural and strength requirements, programmable indexing means to enable the relative positions of the wheelhead and workpiece to be adjusted in a sequence of steps to achieve a sequence of plunge grinds, which may or may not overlap, to enable a region of the workpiece to be ground, the axial extent of which is greater than the width of the wheel, and wheel feed means and control means by which the feed rate is controlled, whereby the wheel feed rate is similarly programmable to enable a feed rate to be achieved which is limited only by the peak and RMS power capabilities of the wheel spindle drive motor, so that the rate of material removal is as high as is compatible with the power capabilities of the machine during each plunge, thereby optimising the total cycle time for grinding.
A method of reducing the time to grind a region of a workpiece having an axial length, comprising the steps of selecting a grinding wheel whose width is less than the axial length of said region and is a narrowest possible given a desired feed rate and an available maximum motive power, but being not substantially wider than is required by wheel strength, causing relative movement between the grinding wheel and the workpiece and performing at least two plunge grinding steps so as to grind said region, wherein at least two of said grinding wheels are provided and the said two at least grinding wheels simultaneously engage the workpiece for grinding, and performing a succession of at least two plunge grinding steps so as to grind the said region.
A method of grinding a region of a workpiece between first and second shoulders having an axial distance therebetween, comprising the steps of selecting a grinding wheel whose width is less than the axial distance between the shoulders, plunge grinding adjacent one of the shoulders, causing relative axial indexing between the wheel and the workpiece, plunge grinding adjacent the other shoulder, and thereafter removing any unground material remaining between the two shoulders by performing at least three plunge grinding steps with appropriate indexing, wherein the indexing is such that one side of the wheel is presented with unground material substantially the same number of times in the sequence of additional plunge grinds as is the other side of the wheel.
A method of grinding an axial region of a workpiece using a grinding wheel which is rotatable by a drive motor and is mounted on a wheelhead and whose width is not substantially greater than that dictated by structural and strength requirements, comprising the steps of programming an indexing drive means of one of the wheelhead and the workpiece to enable the relative positions of the wheelhead and workpiece to be adjusted in a sequence of steps to achieve a sequence of plunge grinds and enable the said axial region of the workpiece to be ground, said axial region having an extent greater than the width of the wheel, programming a computer based machine control system to generate control signals for controlling the rate of wheelfeed during grinding dependent on feedback signals during grinding, entering data into data stores associated with the control system relating to maximum instantaneous and RMS power of the drive motor, and controlling the wheel feed rate by the control system to enable a feed rate to be achieved limited only by peak and RMS power capabilities of the wheel spindle drive motor, so that the rate of material removal is as high as is compatible with the power capabilities of the machine during each plunge, thereby optimizing the total cycle time for grinding, wherein the feedback signals enable each of the instantaneous, and RMS, wheel spindle motor power to be calculated as grinding progresses.
A grinding machine comprising a single wheelhead having mounted thereon a grinding wheel whose width is not substantially greater than that dictated by structural and strength requirements, programmable indexing means to enable the relative positions of the wheelhead and workpiece to be adjusted in a sequence of steps to achieve a sequence of plunge grinds, to enable a region of the workpiece to be ground, the axial extent of which is greater than the width of the wheel, wheel feed means, control means by which the feed rate is controlled, and wherein the wheel feed rate is programmable to enable a feed rate to be selected dependent on the peak and RMS power capabilities of the wheel drive, so that the rate of material removal is as high as is compatible with the power capabilities of the machine during each plunge, thereby optimising the total cycle time for grinding.
Dependencies are inferred from the claim text.