The mechanical knife of the cross cutting machine is mainly driven by the main motor dragging both the double-sided machine and the cross cutting machine at the same time, and the cutting length is adjusted by adjusting the transmission ratio of the mechanical stepless speed control box between the main motor and the cross cutting machine. This determines the mechanical knife has the following disadvantages:

First, the replacement of work orders must be adjusted when the mechanical stepless speed control box ratio and mechanical knife eccentric device. So that the time to change the work order is long and increased scrap.
Second, because the length of the cardboard by the speed control box ratio to adjust, so once the speed control box mechanical wear and tear, gear gap is too large, double-sided machine belt slippage, cardboard precision is difficult to ensure. Therefore, the mechanical knife in about a year after the use of cardboard length error will be too large a phenomenon, cardboard with the production of the higher the speed of its length error is greater. General cardboard length error is greater than 5MM.
Third, the mechanical knife speed control by the main motor to use the slip motor to adjust the speed, due to the slip motor low-speed torque is poor, low efficiency, compared with the frequency control system, power consumption is much larger.

Computer knife transmission structure and mechanical knife of different: double-sided machine and cross-cutting machine are driven by different motors, cross-cutting machine by the computer, speed control system, detection wheel composed of a speed closed-loop control system, by the detection wheel will be detected by the speed of the cardboard and sent to the computer, the computer according to the speed of the cardboard and preset length of the cardboard according to the inherent algorithm calculated cross-cutting machine speed instructions, and the speed instruction sent to the speed control system by the speed control system, by the speed control The speed command is sent to the speed control system, and the speed control system controls the knife speed of the cutting machine, realizing the synchronous control of the paper speed and knife speed.

According to the different speed control system, the computer knife is divided into DC speed control system and AC servo speed control system. Compared with the mechanical knife has the following advantages:
First, the computer knife due to separate control of the cross-cutting knife, cardboard length by predetermined algorithms to adjust the knife speed of the cross-cutting machine to implement, so there is no single mechanical adjustments, thus reducing scrap and progress in productivity.
Second, the mechanical structure of the computer knife is much simpler than the mechanical structure of the knife, cardboard accuracy is not dependent on the accuracy of the machinery to achieve, there is no mechanical wear and tear of the speed control box and other issues. Computerized knife cardboard accuracy mainly by the detection wheel (rotary encoder), speed control system (DC, AC servo) and other electrical components of the resolution and control algorithms, its accuracy is much more reliable than the accuracy of the mechanical knife, computerized knife cardboard accuracy is generally within ± 1 ~ 2MM.
Third, the slippage of the detection wheel will also lead to poor cardboard length accuracy, but the slippage of the detection wheel compared with the slippage of the belt of the double-sided machine to be much lighter, but also much easier to eliminate.