Abstract: This paper analyzes and studies the production process of a carton packaging machine in an automatic bottling packaging line, applies the Siemens servo motion control system to this equipment, and explains the advantages of this control system.
0 Introduction
Heat shrink film packaging offers advantages such as safety, reliability, and ease of transportation and sales, and has been widely used in the domestic beverage industry. However, glass bottles used in beer production are easily damaged by impacts, and the limitations of heat shrink film cannot fully meet the production needs of the beer industry and other related glass bottle packaging industries. Therefore, cardboard box packaging is a high-end, high-specification packaging option for beverages and beer, easily solving the problems associated with long-distance transportation and effectively compensating for the shortcomings of heat shrink film packaging. The two complement each other and are indispensable packaging methods in the modern beverage and beer packaging industry. Previously, my country's cardboard box packaging machines had a packaging capacity of only 35 boxes/min, which could only meet the needs of beverage and beer packaging production lines with a capacity of 20,000 bottles/hour. This paper improves and upgrades existing carton packing machine technology, drawing on the characteristics of domestic and foreign carton packing machines, and successfully develops a fully automatic carton packaging machine with a production capacity of 60 boxes/min using a servo motion control system, effectively solving the production needs of the beverage and beer industry.
1. Introduction to Siemens SIMOTION
In the field of motion control, general motor drivers offer rich motion control functions, but their logic control and complex calculation functions are quite weak. While general PLCs provide comprehensive logic control functions, they rarely possess all the functions required for motion control. The traditional approach is to use a PLC in conjunction with a servo controller, but this presents challenges in high-speed data transmission, data synchronization, and precise control.
Siemens has introduced SIMOTION, a new generation motion control platform. SIMOTION is designed for machines where motion control plays a leading role. It integrates logic control and motion control and can independently perform all the functions of a traditional PLC plus motor speed controller. It is mainly used in fields with complex control requirements, high control speed, and precise motion requirements.
I. SIMOTION is a simple and flexible control system that integrates motion control, logic control, and process control. It has the following advantages:
1. The combination of logic control and motion control eliminates independent interfaces that affect response time.
2. It saves on the investment in programming and diagnostics for these intermediate interfaces.
3. The programming and diagnostics of the entire machine are not only standardized, but also open and transparent, just like a PLC.
II. The SIMOTION system has three components:
1. Engineering Development System
The engineering development system can solve all motion control, logic and process control problems with a single development environment, and it can also provide all the necessary tools, from programming to parameter setting, from testing to fault diagnosis.
2 Real-time software module
These modules offer a wide range of motion control and process control functions. Specific modules can be flexibly selected based on the functions required by a particular machine.
3 Hardware Platform SIMOTIOND
SIMOTIOND's functionality is integrated into the control module of the new SINAMICSS120 multi-axis drive system, making it a compact system with both controller and drive. This integration of motion control and drive enables extremely fast system response. SIMOTIOND is available in several specifications, depending on the performance requirements.
2. Technical Structure and Working Principle of Paper Packaging Machine
2.1 Composition of the control system
The R60 carton packaging machine from Keshimin uses a B&R (B&R) control system. The main control PLC is a CP476 that communicates with all drive servos via a CAN fieldbus. The host computer panel is a PP451, which is also connected via a CAN bus and uses an EX470 to expand remote I/O.
Figure 1. B&R control system diagram for carton packaging machine
The Ethernet address of the PP451 host interface is 01; the CAN fieldbus address of the 3IF771.9 communication card is 09; the CAN fieldbus address of the bottle pusher servo driver is 01; the CAN fieldbus address of the bottle splitting 1 servo driver is 02; the CAN fieldbus address of the bottle splitting 2 servo driver is 03; the CAN fieldbus address of the outlet servo driver is 04; the CAN fieldbus address of the paper suction servo driver is 05; and the CAN fieldbus address of the EX470 bus controller is C6.
The CAN fieldbus number corresponding to each device must be absolutely correct; otherwise, the system will not function properly. Under normal circumstances, after the system is powered on, the CAN communication indicator light on the IF771 will flash rapidly, and the two communication indicator lights on the AC110 communication cards of each servo driver will remain constantly lit; otherwise, communication will be abnormal.
2.2 Composition and Working Principle of Automatic Carton Packaging Machine
The fully automatic high-speed carton packaging machine mainly consists of cardboard feeding, bottle conveying, cardboard board picking, bottle sorting, cardboard board conveying, bottle pushing, carton folding and forming, glue spraying, and sealing. The cardboard board feeding system comprises a cardboard board storage warehouse, cardboard board waiting stations, horizontal cardboard board conveying, main cardboard board supply fork, secondary cardboard board supply fork, and detection switches. It primarily supplies cardboard boards to the packaging machine, meeting the uninterrupted cardboard board supply requirements of high-speed packaging machines, ensuring smoother cardboard board supply. Bottle conveying is divided into two parts: one part uses frequency conversion speed regulation to control the motor speed, conveying bottles on the packaging line in a regular manner according to requirements, with bottle shortage detection ensuring continuous bottle supply to the packaging machine; the other part uses a main drive to mechanically convey bottles according to the machine's operating rhythm. Cardboard board picking is driven by a servo motor, operating synchronously with the main drive in a driven manner. It has two sets of suction cups that alternately pick up cardboard, achieving high-speed cardboard board picking and a cardboard board supply rate of 60 cartons/min. Bottle sorting is controlled by bottle sorting servo motors 1 and 2, along with the main drive motor, to systematically group bottles into 3x4 groups. Cardboard conveying transports the collected cardboard through several stations to the bottle loading area, powered by the main drive. Detection of missing cardboard and double-layer cardboard ensures a normal supply. The bottle pushing mechanism arranges the bottles after sorting, pushing them with push rods. As the bottles pass through the unpowered transition plate, they are arranged closely together, improving packaging quality. Carton folding, glue spraying, and sealing complete the packaging of beer and beverages. The glue spraying location is determined based on the carton structure, and the sealing is adjusted appropriately to ensure sealing quality. Figure 2 shows the workflow diagram of the paper packaging machine.
Figure 2 Production Flow Chart of R60 Automatic Carton Packaging Machine
3 Control System Design
3.1 Main Controller
The main controller primarily controls analog signals, sensors, light sources, drives, positioning, pneumatics, process parameters, processes, operational faults, product quality, and safety. It employs a PLC (Programmable Logic Controller) and related auxiliary systems to achieve real-time and accurate control.
3.2 Multi-motor synchronization technology and servo technology
Packaging materials are conveyed via the main drive system, while auxiliary packaging materials are conveyed via a feeding system. Their interactions require coordination and consistent control. The multi-motor servo control system uses a PLC for control. Detection between different workstations is achieved through peripheral proximity switches, enabling contactless signal input and coordinated electrical, optical, mechanical, and pneumatic actions of the control system. By appropriately adjusting the positions of the bottle separator, sealing cylinder, glue spraying cylinder, and shaping cylinder, packaging of cartons of different sizes can be performed.
3.3 Operating System Design
By utilizing frequency conversion technology and a human-machine interface (HMI), the packaging equipment can be controlled to operate at different speeds in various working modes, including manual, automatic, and debugging modes. The frequency converter communicates via an RS-485 interface, allowing relevant parameters to be displayed and set on the HMI.
4 Control System Scheme
The control system of the high-speed carton packaging machine mainly consists of a motion controller EX470, a PP451 human-machine interface, detection elements, execution elements, servo drivers, and servo motors. The motion controller EX470 controls the servo drivers and servo motors via a CAN bus. Operating parameters are set and controlled via the CAN bus.
The machine's operating position detection and packaging cycle setting are handled by servo control. The servo motor is equipped with a rotary encoder, and the servo controller performs closed-loop control of the servo motor based on the feedback signal from the rotary encoder. An incremental encoder is selected, which generates electrical pulse signals with a frequency proportional to the motor speed. The servo controller counts these pulses and controls the servo motor accordingly. Data is transmitted to the EX470 via a dedicated encoder interface, and the data values indicate the machine's operating position. During packaging, a bottle pusher pushes out a group of bottles to complete one packaging cycle. A detection switch is installed at the point where the bottle pusher passes, used to reset the encoder data recorded in the EX470. This periodic change in data, as recorded in the EX470, indicates the position data within the packaging cycle. Within each packaging cycle, there is a one-to-one correspondence between the data for actions such as picking up cardboard, placing cardboard, and separating bottles and the data in the EX470. Each action of the machine is controlled based on this one-to-one correspondence.
4.1 Bottle dividing motor control system
The bottle-splitting motor drive system consists of two sets of bottle-holding grippers driven by separate bottle-splitting motors. On the packaging machine, bottle transport in the packaging section is achieved via the main drive motor. Bottle sorting involves dividing regularly arranged, closely packed bottles into 3×4 groups or other sizes of combined bottles. On the conveyor chains of the two bottle-splitting motors, two sets of bottle-holding grippers at equal intervals are installed, and the two motors operate alternately at different speeds. This divides the neatly arranged bottles into 3×4 groups, which are then transported to the next workstation via the main drive motor.
The bottle-dividing motors are controlled in a regular alternating pattern, operating at varying speeds. The key feature is that the pulse count of the main drive motor serves as the synchronization signal (X-direction), while the pulse count of the bottle-dividing motor itself (Y-direction) follows a pre-defined motion curve. In other words, the bottle-dividing motors only operate as slave motors, running synchronously along a specific curve, when the main motor is running.
The setting of the synchronization position parameters of the bottle-separating motor determines that the bottle-separating motor operates according to a certain pattern. The start and stop positions of the operation must have a reference position, which can be set on the HMI PP451. The position relative to a certain reference point varies depending on the product and packaging, resulting in different reference positions and motor switching points.
4.2 Cardboard Board Supply System
The cardboard board supply system mainly consists of two parts: horizontal cardboard board supply and vertical cardboard board supply.
Horizontal cardboard board supply. The horizontal cardboard board supply is driven by a horizontal supply motor, which controls the motor by detecting the status of the cardboard board conveyor chain. The cardboard boards are transported from the initial stacking point to the cardboard board waiting station. When the auxiliary fork supports the cardboard board, the main fork descends to the initial position, and the control motor transports the waiting cardboard board to the vertical station, completing one horizontal cardboard board supply cycle.
The carton board supply is vertical. Vertical carton board supply is driven by a vertical supply motor; one motor drives the main support fork, and another motor drives the auxiliary support fork. The main support fork primarily supplies carton boards. When the carton board supply decreases to a certain quantity, the auxiliary support fork supports the remaining carton boards, and the main support fork descends to wait for the remaining boards. Once the carton boards are in position, the auxiliary support fork is withdrawn, and the main support fork resumes normal supply, completing the replenishment of one set of carton boards. This ensures an uninterrupted carton board supply, achieving high-speed packaging.
4.3 Composition and Control of the Paperboard Picking System
Composition of the cardboard tray picking system. The cardboard tray picking system consists of a drive shaft, a synchronous toothed belt, and a driven shaft. The synchronous toothed belt is equipped with two sets of suction cups, and the servo motor and the main drive motor run synchronously back and forth to achieve high-speed cardboard tray picking.
The core control of the cardboard tray picking system is the control of the servo motor. The servo motor drives a synchronous toothed belt, on which two sets of suction cups are installed to pick up the cardboard. When the servo motor rotates forward, the first set of suction cups releases the cardboard tray when it reaches the cardboard placement position, and simultaneously the second set of suction cups moves to pick up the cardboard tray, completing one cardboard tray picking cycle. When the servo motor rotates in reverse, the second set of suction cups releases the cardboard tray when it reaches the cardboard placement position, and simultaneously the first set of suction cups picks up the cardboard tray, completing the next cardboard tray picking cycle.
5 Conclusion
The application of servo control systems makes control more precise; the system is more complete, flexible, stable, and reliable. Using servo motors not only reduces the damage to equipment caused by mechanical shocks, but also significantly reduces the failure rate of equipment using traditional control methods.
This project has been widely applied to paper packaging machines produced by Keshimin Packaging Equipment Co., Ltd., and the produced carton packaging machines are exported to Europe, America, Southeast Asia and other regions and countries.
