现有的大多数钢琴,弦轴直径为7毫米,轴颈外圆带有滚纹,弦轴靠后部钻有一个φ1.8毫米的穿弦孔,其末端为方头。当钢琴使用时间较久后,会由于下述原因无法再通过弦轴将琴弦调到要求的音高: (1)弦轴板不断干燥,含水率降低,使弦轴孔扩大。 (2)弦轴孔被磨大,轴颈上的滚纹磨 Most existing pianos have a string diameter of 7 millimeters, a roll of the journal outer circle, and a φ1.8 millimeter string of string holes drilled to the rear of the string, the ends of which are squared. When the piano is used for a long time, the strings can no longer be tuned to the desired pitch through the pegs for the following reasons: (1) The pegboard is continuously dried and the moisture content is reduced, allowing the peg to expand. (2) string shaft hole is grinded, journal rolling on the mill