In the past, the labeling position detected by the automatic labeling machine was based on the front edge of the box as the photosensitive point. Because box of different diameters need to be moved by the corresponding electric eye or the labeling time is changed, if this change is not made, the labeling cannot be guaranteed on each box. The requested location. Products are equipped with the "automatically calculate label length" function, which effectively compensates for the above weaknesses. "Automatic label length calculation" is an automatic control technology formed by the combination of PLC and servo motor technology. When the conveyor belt box passes the detection electric eye, the radius of the box is measured, and the most prominent point on the outer edge of the box is taken as the sticker. The sensing point of the label signal, that is, no matter how small the diameter of the box is, the most protruding point on the outer circumference of the box is the sensing point of the labeling signal, so that the distance between the electric eye and the peeling plate does not need to be mechanically adjusted. There is no need to adjust the label time at all. This is the automatic control principle of automatically calculate label length. This is also people's first choice for the functions of the automatic labeling machine.