| 摘要 |
<p>An endless abrasive belt runs on a contact wheel and on an idler wheel to perform grinding and sharpening operations on a rotary lawnmower blade. The cutting edges of such a blade are on the outermost ends thereof, and are each defined by the intersection of the flat face side of the blade and a surface ground away at an acute angle with the flat face of the blade. For each cutting edge, there is a taper back to the outer leading edge of the bar stock of which the blade is made. The grinding or sharpening is done in the usual manner for abrasive belt grinding wherein an endless coated abrasive belt is backed by a contact wheel having a cylindrical backup face, but the edge of the contact wheel adjacent the taper is relieved on a radius, and the endless belt extends out over this relieved radius and past the outer edge of the contact wheel. When the work is pushed against the abrasive belt and contact wheel, the grinding pressure exerted by the belt extending out over the radius and past the wheel varies from full pressure at the point where the relief starts, out to the outer edge of the belt where the only pressure is that occasioned by the centrifugal action of the abrasive belt itself. The result achieved is a smooth, even taper from the point of full contact with the wheel to a point where the abrasive belt is no longer in contact with the workpiece.</p> |
