Method for operating a textile machine producing cross-wound bobbins

In the operation of a spinning machine with a plurality of spinning stations (1), each comprising a take-off device (27) with a take-off roller (10) and a pressure roller (14) for drawing off a yarn (9) from a spinning device (2) and a sensor mechanism (26) for checking piecings, a method of detecting the wear condition of the pressure roller characterised by the following steps:

• at the start of a piecing, the theoretical conveying length of the yarn (9) is determined on the basis of the surface speed of the pair (10, 14) of take-off rollers, until the beginning of the piecing has reached the sensor mechanism (26),
• the deviation of the theoretical conveying length from a desired yarn length, corresponding to the spacing between the spinning device (2) and the sensor mechanism (26), is detected,
• the deviation is compared with a preadjustable limit value of the permissible deviation, and
• passing the limit value is evaluated as an indicator of intolerable wear of the pressure roller (14) and signals an alert to a user indicative of the wear of the pressure roller.