Design of Electrical Control System for Paper Core Continuous Automatic Honeycomb Paperboard Production Line

Abstract: The production technology of horizontal honeycomb, longitudinal cutting and paper core continuous honeycomb paperboard can increase production efficiency and achieve full automatic production. Based on PLC with PID regulation of frequency control and tension adjustment closed-loop control system design program, to meet the paper core continuous automatic production control requirements.

Key words: honeycomb paperboard production line; paper core continuous; PLC; speed synchronization; tension; control system design

0 Preface

Honeycomb paperboard is an emerging environmentally friendly and economical packaging material based on paper for wood in the packaging industry. At present, domestic and foreign companies basically adopt longitudinal paper coating and transverse cutting paper core discontinuous production technology for production. Due to the process itself, its production equipment is limited in terms of automation, paper core width, and production efficiency. If horizontal gluing, longitudinal cutting, and continuous paper core production processes are adopted, many shortcomings of the traditional production process can be overcome. However, it is necessary to solve the tension change during the multi-layer paper feeding process, the deviation of the glue strip position and the production line. Segment equipment speed chain synchronization and other process control issues. If these problems are not solved, it is difficult to achieve a continuous production process of the paper core. The electrical control system scheme introduced in this paper solves the above problems and successfully realizes the continuous automatic production of paper cores.

1 production process and control requirements

The production process of paper core continuous automatic honeycomb paperboard production line is:

(1) Feeding 6-layer paper feeding mechanism; (2) Horizontal gluing in accordance with the formation of a honeycomb-shaped rubber strip interval gluing; (3) Laminating processing Pressing together the glued 6-layer paper (4) slitting and gluing slitting into six layers of paper strips of the same size according to the requirements of the thickness of honeycomb paperboard products, and coating each strip after slitting to form strips of honeycomb; (5) strips of paper Polymerization bonds the stripped honeycomb paper strips together to form a multi-layered honeycomb paper core; (6) The core of the paper draws and pulls the paper core to form a honeycomb and shape; (7) The paper core composite surface will be shaped After the opened honeycomb paper core cover the paper surface; (8) roll press molding to cover the surface of the paper after the paperboard pressure fixing; (9) cutting board according to the requirements of honeycomb paperboard product size requirements such as cutting. Each of the above processes is completed by an independent dedicated equipment, in which: (1) to (5) processes are continuous paper core production equipment, and (6) to (9) are cardboard production equipment. All process equipment of the production line must not only fulfill the operational requirements of this section of the process, but also coordinate with the equipment of the front and back process sections. Therefore, the electrical control system needs to have: (1) automatic control and single manual adjustment; (2) run/stop, run speed up/down control and digital display speed function; (3) tracking speed chain Synchronization function; (4) tension automatic adjustment function; (5) automatic cutting board and human-machine interface monitoring function.

2 control system solutions and hardware configuration

In order to meet the process requirements, in accordance with the principle of simple operation, reasonable design, reliable operation and easy maintenance, in accordance with the requirements of the above production process on the control system, the system has selected the medium-scale FP10s programmable controller manufactured by Panasonic Electric Works as the main control. The unit's electrical control system is shown in Figure 1. In Figure 1, the control system hardware can be divided into the following five parts.

2.1 Automatic control and manual control The control system is divided into two parts: centralized control and manual control. In the automatic control, the entire console is controlled by the master console. The master console is composed of a touch screen and button switches such as total start, total stop, and operation. The 1-9 control panel is the operating panel of the 1-9 process sections, which are respectively installed on the equipment in the corresponding process section. It is used to manually control and adjust the operation of the equipment in this section and display the status of the equipment in the section, such as speed adjustment, Automatic manual conversion, start, stop, emergency stop, speed display, fault alarm, etc.

2.2 Frequency Control System

There are a total of 9 devices across the board. The devices 1 to 8 are driven by variable frequency motors, and the device 9 is a cutting device. Due to the requirements of the production process, the 1 to 5 paper core production equipment is a speed synchronization section, and the 6 to 9 paperboard production equipment is another speed synchronization section, and it is required that the sectional equipment have the functions of synchronous speed increase and synchronous speed reduction respectively. A closed loop control variable frequency speed regulation scheme with PID adjustment function was adopted [1-3].

According to the requirements of PID closed-loop control, the hardware configuration of each frequency conversion speed control system of each device consists of a rotary encoder, a high-speed counting module, a digital-analog conversion module, and a public FPIOs CPU. The system structure is shown in Figure 2.

The control principle of the speed synchronization is: the first process control is controlled by comparing the speed setting value obtained by manual speed adjustment on the touch screen or a 1 point control screen with the actual rotation speed of the motor; in the subsequent processes, before the monitoring The speed difference between the motor speeds of one process and the current process is corrected by PID control to reduce the speed difference between the two. Through this control method, it is possible to achieve smooth linkage between various processes, to meet the requirement of speed synchronization of the process, and to achieve the purpose of improving product quality.
2.3 Tension Adjustment In the paper feeding mechanism, in order to achieve evenness of the rubber strip coated on the 6-layer paper, the feed tension of the 6-layer paper must be consistent, so as to ensure the formation quality of the honeycomb paper core. The tension adjustment system in the system is composed of a tension sensor, a tension transmitter, an ADC module, a DAC module, a power amplifier, and a magnetic powder clutch [4, 5], as shown in FIG. 3 .

The magnetic clutch acts as a damper and is mounted on the roll holder shaft. During work, the tension signal measured by the tension sensor is sent to the A/D module of the PLC by the tension transmitter. The CPU compares the measured tension data with the set value, and completes the tension feedback PID adjustment after the PID calculation ( See Figure 4), and then output 4~20mA current signal through PI C's D/A module, and after being amplified by the power amplifier, control the magnetic powder clutch to adjust so as to control the torque of the rotating shaft to achieve the purpose of controlling the tension of the fed paper. .

2.4 Board

Cutting board is the last process in the production line. In this process, it is required to cut and output according to the size of the product and require statistical production. The basic configuration of the panel system is: rotary encoder, high-speed counting module, pneumatic actuator and output control unit. The working principle of the cutting board system is as follows: When the measuring length is equal to the product size set on the touch screen, the cutting cylinder is driven to perform cutting, the control unit is driven to move, the product is removed, and the production is counted once.

2.5 Human Machine Interface

The system has selected the Panasonic SV52 touch screen as the man-machine interface, installed on the general console, and the operator can monitor the working status of the entire line through the touch screen. In the man-machine interface, a number of pictures are designed, including the overall picture, fault display, speed display at each point, production statistics display, and various parameter settings and other monitoring screens.

3 system software

The control software is mainly composed of an initialization module, an analog quantity acquisition module, a filtering module, a PID calculation module, and a switch quantity control input and output module.

3.1 Initialization module

During initialization, the program mainly assigns initial values ​​to the relevant variables, such as setting the timer's time constant, PID parameters, and so on.

3.2 Speed ​​Measurement and Adjustment Module

The system has a total of 8 rotary encoders, which are respectively connected to the 8 input channels of the high-speed counting module. The PLC calculates the front-end motor rotor speed V1/r·min-1 and the current motor rotor speed V2/r·min-1. According to the following formula, the linear velocity of each driving roller is calculated as V line = kvπD/m · min-1, where k is the transmission ratio of the motor rotor speed, and D is the transmission roller diameter/m. The line speed of the front drive roller is used as the line speed setting (SP) of the current drive roller, and the line speed of the current drive roller is used as the measured value (PV). The PID command provided by the FPIOS is used to calculate the speed. The D/A module Output 4 ~ 20 mA current signal, sent to the input of the inverter to adjust.

3.3 Analog acquisition, filtering and tension adjustment module The system has 6 channels of tension transmitter input analog measurement feedback signal, are 4 ~ 20 mA, by two 4-way analog-to-digital conversion module for A / D Conversion. Digital filtering is used in the sampling, removing a maximum and a minimum and then averaging as the filtering result (PV). In order to improve the dynamic and steady-state performance of the system, the control tuning uses a PID algorithm with insensitive zones [6]. The algorithm makes the following limitations on the standard PID control output. SV is the set value, e is the difference between the set value (SV) and the measured value (PV), and D is the bandwidth of the insensitivity zone. When D is zero, it is the standard PID algorithm; when D is not zero, if lel>D, then the PID algorithm is executed. If le l≤D, the control output value U0 is the set value SV. In this control system, the size of D is determined by the maximum deviation of the tension of the 6-fed human paper during stable production.

4 Concluding remarks The paper core continuous automatic honeycomb paperboard production line has a relatively large electrical control system. The switch quantity I/0 has more than 300 points, but only when the tension of the multilayer paper feeding process is changed, and the speed chain of each segment of the production line is synchronized. Problems can be achieved in continuous automatic production of paper core [6]. The above-mentioned electrical control system scheme has been successfully used in a continuous automatic paper honeycomb paperboard production line and has met the design requirements.

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Reprinted from: Department of Electrical Engineering, Anyang Institute of Technology