Unova UK Limited

Stephen Roger Coverdale

Michael Laycock

David Thomas Proctor

Christopher Shaun Thorpe

A method is described for grinding a crankpin of a crankshaft using computer controlled wheelfeed and headstock drives ( ). During a final grinding step leading to finish size the cutting force is maintained on the wheelhead ( ) to keep the wheel ( ) and pin under a moderate constant load and the rotational speed of the headstock drive ( ) is reduced. This serves to prevent bounce and chatter marks appearing in the surface of the pin. The rotational speed is typically in the range of 1 to 5 rpm. During the final step of grinding each pin, the wheelfeed is adjusted so as to remove a sufficient depth of material during a single rotation of the crankshaft, to bring the crankpin to finish size. In order to determine the depth of cut required, each pin is gauged

Crankpin grinding method

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.

Grinding methods and apparatus

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 fo 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.

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Shipley, United Kingdom

Stephen Roger Coverdale