| 摘要 |
<p>941,313. Sharpening saw chains; sawing. OMARK INDUSTRIES Inc. Feb. 11, 1960 [Oct. 12, 1959], No. 4937/60. Headings B3D and B3L. [Also in Division B5] A saw chain which has cutter links on which cutting edges are formed rearwardly, in respect of the direction of chain travel, of the midpoint of a line between the axes of the cutter link pivots is sharpened by mounting a sharpening member on the said frame adjacent to a driving sprocket for the chain and bringing this member into contact with the outer surfaces formed on the cutter links rearwardly of the cutting edges as the chain travels around the sprocket, the radius of the path of travel of the outer surfaces around the sprocket being smaller than the radius of the path of travel of those outer surfaces around the nose end of the saw bar supporting the chain. A chain saw, Fig. 1, has a body 24 to which is secured a saw bar 28. A scratcher saw chain 26 is mounted upon the bar 28 and upon a sprocket 30 driven by a motor (not shown), the sprocket having a smaller pitch radius than the pitch radius of the nose end 34 of the bar 28. A saw chain sharpening device 22 comprises a base block 46 pivotally secured to the body 24 by a screw 48. A clamping screw 54 carried by the body 24 passes through an arcuate slot in the block 46 concentric with the axis of the screw 48, so as to clamp the block 46 in either the operative or inoperative position. A slide 62 vertically adjustable on the block 46 by a screw 74 has rotatably mounted therein a cylindrical sharpening element 36, the axis of which is inclined to the direction of motion of the slide 62 so that downward adjustment of the slide 62 advances the sharpening element 36 toward the saw chain 26 on the sprocket 30. The axis of the sharpening element is in the central plane of the saw chain 26 and sprocket 30. The sharpening element may be of tungsten carbide, tantalum carbide, or titanium carbide, the cylindrical surface being provided with a plurality of helical cutting teeth so that, in use, the sharpening element rotates to distribute the wear circumferentially around it. Soft metal with diamonds or other hard materials embedded therein may be used, the teeth being omitted. In a modification, Fig. 8, the sharpening device comprises a grinding wheel 130, with bevelled edges 132, mounted on a shaft 120 journalled in a block 121 movable, in the casing 116, towards and away from the main drive shaft 118 by a screw 127. The shaft 120 is driven from the shaft 118 by a pulley 124, belt 122 and spring expansible pulley 126. A pressure dresser is rotatably mounted on the end of a lever pivoted to the casing 116 so that the dresser can be manually held against the periphery of the grinding wheel 130. Specification 941,314 is referred to.</p> |
