Today's corrugated paper cutting machines mainly include mechanical knives and computer knives. There are two kinds of computer knives, direct current systems and AC frequency conversion systems.
The mechanical knife is mainly driven by the main motor at the same time, the double-sided machine and the cross-cutting machine, 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 that the mechanical knife has the following disadvantages:
1. When changing the work order, the gear ratio of the mechanical stepless speed control box and the eccentric device of the mechanical knife must be adjusted. Make the renewal work order longer and more waste.
2. Because the length of the paperboard is adjusted by the transmission ratio of the speed control box, once the gear box is mechanically worn and the gear clearance is too large, the double-sided machine belt slips, and the accuracy of the paper board is difficult to guarantee. Therefore, the paperboard will have an excessively long paperboard length error after about one year of use. The higher the paperboard production speed, the greater the length error. The general cardboard length error is greater than 5MM.
3, the speed of the mechanical knife depends on the main motor to use the slip motor to adjust speed, because the slip motor has low torque and low efficiency, compared with the variable frequency speed control system, the power consumption is much larger.
The drive mechanism 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. The cross-cutting machine consists of a computer, a speed control system, and a detection wheel to form a speed closed-loop control system. The speed is detected and sent to the computer. The computer calculates the speed command of the cross-cutting machine according to the inherent algorithm based on the speed of the board and the preset board length, and sends the speed command to the speed control system. The speed control system controls the knife of the cross-cutting machine. Speed, realize synchronous control of paper speed and knife speed.
According to the different speed control system, the computer knife is divided into the DC speed control system and the AC servo speed control system. Compared with the mechanical knife has the following advantages:
1. Since the computer knife independently controls the cross cutter, the length of the cardboard board is adjusted by a predetermined algorithm to adjust the cross cutter speed, so there is no mechanical adjustment at the time of single change, thereby reducing waste and increasing productivity.
2. The mechanical structure of computer knives is much simpler than that of mechanical knives. The accuracy of cardboard is also not achieved by mechanical precision, and there are no problems such as the mechanical wear of the governor box. The accuracy of the computer knife's board is mainly determined by the resolution of the electrical components such as the detection wheel (rotary encoder), speed control system (DC, AC servo), and the control algorithm. The precision of the computer knife is much more reliable than that of the mechanical knife. The knife's cardboard accuracy is generally within +/-1~2MM.
3. The skidding of the inspection wheel also leads to a deterioration of the board's length accuracy. However, the slippage of the inspection wheel is much lighter than that of the belt of the double-sided machine and can be easily eliminated.
Computer knife's DC speed control system and AC servo speed control system control cross-cutting machine's cardboard accuracy and production efficiency are higher than the mechanical knife's precision, but the DC speed control system has the following disadvantages:
1, the cost is about 20% higher than the AC variable frequency speed control system
2. The power consumption is about 10~15% higher than the AC variable frequency speed control system
3, the DC system has a dead zone at low speed, resulting in unstable control
4, carbon brush DC motor must be regularly maintained and replaced
Therefore, the computer-wide AC frequency conversion control system is the best control system for corrugated paper cutting machines.
introduction
QP-II corrugated paper cross cutting machine is a computer-wide AC servo frequency conversion control system developed by the company. After two major improvements, it has become the most advanced corrugated paper cross cutting machine control system in China. The composition of its system is as follows:
The cross cutting machine computer control system is mainly composed of the upper computer, the lower computer, the servo actuator, the signal acquisition element and the transformation circuit, and the man-machine dialogue control cabinet.
1. The basic functions and configuration of the host computer
The system adopts two-level computer control. The host computer mainly completes data provision, screen display and some management and control functions. It can arrange hundreds of groups to cut orders and record production data, and is equipped with self-learning software to compensate and correct each The shear error caused by this condition. The upper computer adopts the industrial control computer suitable for the industrial site, and the keyboard adopts a membrane keyboard with dustproof. Has the characteristics of adapting to the dust on the scene environment. Its communication with the lower computer is through the RS-232/422 serial port communication module, which has the characteristics of strong anti-interference ability.
2. The lower computer (central processing unit) adopts the programmable controller of Japan Mitsubishi, which is the core of the entire control system. Responsible for processing the collected signals, issuing instructions in accordance with the principle of servo control, to complete a series of controls.
3. The speed and position detection components of the spindle drive and servo control of this system adopt rotary encoders. Its high precision and high reliability provide the possibility of high precision servo control.
4, the implementation of the system uses AC servo drive and high-power AC servo motor. Its large starting torque and high speed accuracy provide a guarantee for high speed, high precision production.
5. The knife holder adopts a computer cross cutting knife with no eccentric device, and the connection between the motor and the knife holder is a deceleration mechanism with no clearance.
6. The paper feed motor (ie spindle drive) adopts variable frequency servo control. In this way, the paper feeding speed can be stabilized, the cutting accuracy of the paperboard can be improved, and the braking power can be shared with the motor of the cross cutting machine to realize the communication. Servo regenerative braking saves more than 30% energy compared to mechanical knives.
Investment and return
The cost of a computerized knife that is changed from a mechanical knife to a QP-II AC servo controlled by a corrugated paper cutting machine is ¥32,0000.00.
With a 1.6 m watt line, a monthly production value of ¥5000000.00 and an electricity fee of ¥1.00, the production cycle is calculated every day for 8 hours:
A) The cutting accuracy of the mechanical knife is +/-5MM or more, the cutting accuracy of the computer knife is +/-1~2MM, the average cardboard length is 1200MM, and the side increases the cutting accuracy by one monthly cost savings:
Output value*accuracy/average board length=output value*0.005=Â¥25000.00
B) The power consumption of the double-sided machine of the 1.6-metre mechanical knife is about 25KW/H, while the power consumption of the double-serve and cross-cutting machine of the AC servo computer knife is only 10KW/H or less, and the production is calculated every day for 8 hours. The monthly electricity fee is: (25-10)*8*30*1.00=3600.00
C) mechanical knife to ensure the accuracy of +/- 5MM, the general production speed can not be greater than 80 meters / minute, and the AC servo frequency conversion computer knife can produce speeds up to 100 ~ 120 meters / min, plus its replacement single quick This greatly improves the production efficiency, and also reduces the heating, pressurization, and transmission energy consumption of single-sided machines, gluing machines, and double-sided machines.
Based on the above, the investment in retrofitting the crosscutting machine can be recovered within one year.
Ningbo Wellcome Trading Co., Ltd. , https://www.huike-homecare.com