The conical structure makes the blade of QZ202 split paper cutter drop faster. When the tool holder is at the lowest position, the top of the cone body will hit the limit switch, and the tool holder can return quickly. The power-off time of this structure is very short, but the instantaneous break and make-up is the great hidden trouble of connecting knife. In view of this situation, the top of the limit switch cam of the paper cutter can be changed from a cone-shaped impact block to an elliptical stop switch mechanism, and the power-off buffer part of the top position can be lengthened to effectively prevent the instantaneous break and instant on.            2. If the limit travel switch is out of control, the limit switch will not be disconnected. QZ202 paper cutter switch has two groups of contacts, but only one of them is used. During the operation of the paper cutter, the contact will inevitably fail. When the limit stroke is hit, the power can not be cut off on time. Using the idle group of travel switch can increase the power-off probability and reduce the contact failure probability to more than half.            3. Cutting control relay. The intermediate relay of QZ202 folio paper cutter is jz7-44 type, which is only suitable for non frequent action occasions. The contact can flow resistance load AC380V / 5A, dc127v / 5A. However, the secondary output load of this type of paper cutter is dc32v / 3.2a, and it is inductive load. The impulse current is large, which is more than 7 times higher than the contact withstand voltage. Therefore, the contact spark is large, easy to burn and blacken, increase the contact resistance and reduce the circuit voltage. However, if the contact bears the inductive current for a long time, it will cause the contact to act as the finger ring, which will lead to the fault of connecting the knife. Cj10-20a contactor with arc extinguishing cover has the characteristics of large contact over-current, small spark, long service life and sensitive action, which is suitable for frequent opening and closing occasions. It has been proved by practice that the effect has been improved a lot after using this kind of contactor.