The mechanical cutter of the cross-cutting machine mainly drives the double-sided machine and the cross-cutting machine at the same time by the main motor, and adjusts the cutting length by adjusting the transmission ratio of the mechanical stepless speed regulating box between the main motor and the cross-cutting machine. This determines that the mechanical knife has the following disadvantages:
          First, when changing the work order, the transmission ratio of the mechanical stepless speed control box and the eccentric device of the mechanical knife must be adjusted. Increase the length of time for the work order and increase the waste.
          Second, since the length of the cardboard is adjusted by the gear ratio of the speed control box, once the gearbox has mechanical wear and the gear gap is too large, the double-sided belt slips, and the accuracy of the cardboard is difficult to ensure. Therefore, the mechanical knife will have an excessively large error in the length of the cardboard after about one year of use. The higher the speed of the paperboard, the greater the error of the length. Generally, the board length error is greater than 5MM.

         Third, the speed of the mechanical knife depends on the main motor to use the slip motor to adjust the speed. Because of the low speed torque difference and low efficiency of the slip motor, compared with the variable frequency speed control system, the power consumption is much larger.

         The transmission structure of the computer knife is different from that of the mechanical knife: the double-sided machine and the cross-cutting machine are respectively driven by different motors, and the cross-cutting machine is composed of a computer, a speed control system and a detection wheel to form a speed closed-loop control system, and the detection wheel turns the cardboard The speed is detected and sent to the computer. The computer calculates the speed command of the cross-cutting machine according to the speed of the cardboard and the preset length of the cardboard, and sends the speed command to the speed control system. The speed control system controls the cutter of the cross-cutting machine. Speed, synchronous control of paper speed and tool speed.
         According to the difference of the speed control system, the computer knife is divided into the DC speed control system and the AC servo speed control system. Compared with mechanical knives, it has the following advantages:
         First, the computer knife is controlled by the cross cutter, and the length of the cardboard is adjusted by a predetermined algorithm to adjust the cutter speed of the cross cutter. Therefore, there is no mechanical adjustment when the sheet is changed, thereby reducing waste and improving productivity.
         Second, the mechanical structure of the computer knife is much simpler than that of the mechanical knife. The accuracy of the cardboard is not realized by the precision of the machine, and there is no such problem as the mechanical wear of the speed control box. The board accuracy of the computer knife is mainly determined by the resolution of the electrical components such as the detection wheel (rotary encoder), the speed control system (DC, AC servo) and the control algorithm. The accuracy is much more reliable than the accuracy of the mechanical knife. The board accuracy of the knife is generally within ±1~2MM.
         Third, the slip of the detection wheel can also cause the accuracy of the length of the cardboard to be deteriorated, but the slip of the detecting wheel is much lighter than that of the double-sided belt, and is easily eliminated.