Transformation scheme of the hottest corrugated pa

2022-08-26
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Corrugated paper crosscutting machine transformation plan

today's corrugated paper crosscutting machine is mainly divided into mechanical knife and computer knife. From the control system, computer knife has DC system and AC frequency conversion system

the mechanical knife is mainly driven by the main motor at the same time, and the cutting length is adjusted by adjusting the transmission ratio of the mechanical stepless speed regulation box between the main motor and the crosscutting machine. This determines that the mechanical knife has the following disadvantages:

1. When changing the work order, the transmission ratio of the mechanical stepless speed regulation box and the eccentric device of the mechanical knife must be adjusted. It will take a long time to change work orders and increase waste products

2. Since the length of the paperboard is adjusted by the transmission ratio of the speed governing box, once the speed governing box is mechanically worn, the gear gap is too large, and the belt of the double-sided machine slips, the accuracy of the paperboard is difficult to guarantee. Therefore, after using the mechanical knife for about a year, the length error of paperboard will be too large. The higher the production speed of paperboard, the greater the length error. Generally, the length error of paperboard is greater than 5mm

3. The speed regulation of the mechanical knife depends on the slip motor used by the main motor. Due to the poor low-speed torque and low efficiency of the slip motor, compared with the variable-frequency speed regulation 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 crosscutting machine are driven by different motors respectively. The crosscutting machine consists of a speed closed-loop control system composed of a computer, a speed regulation system and a detection wheel. The detection wheel detects the speed of the cardboard and sends it to the computer. The computer calculates the speed command of the crosscutting machine according to the speed of the cardboard and the preset length of the cardboard according to the inherent algorithm, and sends the speed command to the speed regulation system, The speed control system controls the knife speed of the crosscutting machine to realize the synchronous control of paper speed and knife speed

according to the different speed regulation systems, the computer knife is divided into DC speed regulation system and AC servo speed regulation system. Compared with the mechanical knife, it has the following advantages:

1. The computer knife controls the crosscutting knife alone, and the length of the paperboard is implemented by adjusting the knife speed of the crosscutting machine with a predetermined algorithm. Therefore, there is no mechanical adjustment when changing orders, so as to reduce scrap and improve productivity

2. The mechanical structure of the computer knife is much simpler than that of the mechanical knife. The accuracy of the paperboard is not achieved by mechanical accuracy, and there are no problems such as mechanical wear of the speed box. The accuracy of the cardboard of the computer knife can mainly ensure the time-division infinite closedown of the experiment. The accuracy value depends on the resolution and control algorithm of the electrical components such as the detection wheel (rotary encoder), speed regulation system (DC, AC servo) and so on. Its accuracy will be much more reliable than the precise use of the mechanical knife. The accuracy of the cardboard of the computer knife is generally within +/- 1~2mm

3. The slip of the detection wheel will also lead to the poor length accuracy of the paperboard, but the slip of the detection wheel is much lighter and easier to eliminate than that of the double-sided machine belt

the DC speed regulation system and AC servo speed regulation system of the computer knife control the accuracy and production efficiency of the paperboard of the crosscutting machine, but the DC speed regulation system has the following disadvantages:

1, the cost is about 20% higher than the AC frequency conversion speed regulation system

2, the power consumption is about 10~15% higher than the AC frequency speed regulation system

3, the DC system has a dead zone at low speed, resulting in unstable control

4 The carbon brush of DC motor must be maintained and replaced regularly. Therefore, the full computer AC variable frequency control system is the best control system of corrugated paper crosscutting machine at present

system introduction

qp-ii corrugated paper crosscutting machine full computer AC servo frequency conversion control system is developed by our company. After two major improvements, it has become the most advanced corrugated paper crosscutting machine control system in China. The composition of the system is as follows:

the computer control system of the crosscutting machine is mainly composed of upper computer, lower computer, servo actuator, signal acquisition components and transformation circuit, man-machine dialogue control cabinet and other parts:

1. The basic functions and configuration of the upper computer

this system 1. First, daily maintenance adopts two-level computer control, and the upper computer mainly completes the data setting, The screen display and some management control functions can arrange hundreds of groups of cutting orders and record production data, and are configured with self-learning software to compensate and correct the cutting errors caused by various conditions. The upper computer adopts the industrial control computer suitable for industrial site, and the keyboard adopts the membrane keyboard with dust prevention. It is suitable for the site environment with large dust. It communicates with the lower computer through rs-232/422 serial port communication module, which has strong anti-interference ability

2. The lower computer (central processing unit) adopts the programmable controller of Mitsubishi Corporation of Japan, which is the core of the whole 6.4 speed control system. Be responsible for processing the collected signals, sending instructions according to the principle of servo control, and completing a series of controls

3. The speed and position detection components of the spindle drive and servo control of the system adopt rotary encoder. Its characteristics of high precision and high reliability provide feasibility for servo high-precision control

4. The actuator of the system adopts AC servo frequency converter and high-power AC servo motor. Its characteristics of large starting torque and high speed accuracy provide guarantee for high-speed and high-precision production

5. The knife rest adopts the computer cross cutting knife without eccentric device, and the connection between the motor and the knife rest is a reduction mechanism with clearance elimination

6. The paper feeding motor (i.e. spindle drive) adopts variable-frequency servo control, which can stabilize the speed of paper feeding and improve the shearing accuracy of paperboard. In addition, it can share the braking power with the motor of the crosscutting machine to realize AC servo regenerative braking. Compared with the mechanical knife, the energy saving can reach more than 30%

investment and return

the cost of changing the corrugated paper crosscutting machine from mechanical knife to qp-ii AC servo frequency conversion controlled computer knife is ¥ 320000.00

take 1.6m corrugated wire and monthly output value as ¥ 00. The electricity charge is ¥ 1.00, and the calculation return period is 8 hours per day:

a) the cutting accuracy of the machine knife is more than +/-5mm, and the cutting accuracy of the computer knife is +/-1~2mm. Based on the average paperboard length of 1200mm, improving the cutting accuracy on the side can save costs every month:

production value * poor accuracy/average paperboard length = output value *0.005= ¥ 25000.00

b) the power consumption of the double-sided machine of the 1.6m line machine knife is about 25kw/h, However, the power consumption of the double-sided machine and the crosscutting machine of the AC servo variable-frequency computer knife is only below 10kw/h. Based on the production of 8 hours per day, the monthly electricity saving charge is: () *8*30*1.00=3600.00

c) the accuracy of +/-5mm should be guaranteed for the mechanical knife, and the general production speed cannot be greater than 80 m/min. however, the production speed of the AC servo variable-frequency computer knife can reach 100~120 M/min. coupled with its fast order change, this greatly improves the production efficiency, At the same time, it also reduces the heating, pressurization and transmission energy consumption of single-sided machine, gelatinizer and double-sided machine

based on the above, the investment in transforming the crosscutting machine can be recovered within one year

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