Packaging
Robot-supported processing of fish and seafood
Monday 18. April 2011 - The path is the goal
With its robot-supported processing and packing system for fish and shrimps Cabinplant A/S has followed a completely new path: Products are no longer processed in individual, linked steps. Instead, all processing is performed on the path from the conveyor belt to the package. The technical basis of this system is the ELAU PacDrive technology, which unifies motion control, PLC, and robotics on one single control platform.
Cabinplant A/S, with headquarters in the Danish town of Haarby, specializes in machines and production lines for processing and packing of fish and vegetables, as well as for manufacture of convenience food products. The company, which was founded in 1969 and is still privately owned, has more than 230 employees and has subsidiaries in Germany, Spain, Russia and Poland. Cabinplants products range from individual machines to turn-key systems. The core competences of the company are a. o. within the weighing, filling, and packing technologies.
Cabinplant A/S has made a completely new approach by combining food processing and packing in a robot-supported system processing and packing fish or shrimps. All processing steps (cutting off heads and tails, removal of viscera) are performed during the pick-and-place operation, by which a robot transports individual products from a feed conveyor into a package. At a single stroke this procedure eliminates a number of the handling steps required to link individual processing stations by traditional methods, which also take up extra time and space. The new system provides an integrated process with an uninterrupted automatic sequence and setting of new standards as to space-saving and throughput rate.
Fully stainless steel design – including robots
The compact system has easy access from all sides and consists of a bunker with an elevator belt, a vibratory conveyor, a robot cell with a continuous conveyor belt, and an image processing system throughout the feeding area of the conveyor belt. A variable number of integrated Delta 3 robots, all equipped with identical multifunction tools, can approach the conveyor belt. A conveyor chain runs on both sides of the belt to deliver and remove the packages. The entire system, including the robots, is designed in stainless steel to facilitate cleaning.
The process begins in the bunker, in which the fishes or shrimps are kept as bulk material. An elevator belt takes the products from the bunker to the vibratory conveyor. On this belt the product layer is spread to cover the entire width of the conveyor belt, and the single products are pre-aligned. On delivery to the conveyor belt, a camera records the position of each individual product and determines its length. Based on this length a software algorithm developed by Cabinplant A/S calculates the weight without the use of scales.
The continuous conveyor belt transports the products into the work envelope of the robot. The robot picks up the products individually and makes use of the multifunction tool to perform all the processing steps: A cutting tool removes heads and tails (only heads for shrimps). A suction tool is inserted to remove the viscera. The system calculates the position of each product based on camera information and belt movements. One vision system is sufficient for up to five robots. Another system is required for a larger number of robots.
The robot places the fully processed and properly aligned products into the package, which is continuously filled and moved along the conveyor. The single or multiple robots are capable of cross-packing the sardines with belly side upwards into cans on both sides of the conveyor belt. The products can be packed in alternating directions to facilitate space utilization and to create a more appetizing presentation of the contents. Several types of cans can be used, including Dingley and Club cans.
Giveaway reduced by up to 12 percent
The filling process is controlled by weight, similar to the principle of a multihead weigher, although it is based exclusively on the data obtained from an optical measurement/weight calculation. To minimize giveaway when filling the package, the robot combines products, the joint weight of which is as close as possible to the minimum weight. A further advantage is that the cutting of sardines is carried out individually, enabling cutting in the best possible position. According to Mr Henning Ingemann Hansen, R&D Director at Cabinplant A/S, the use of this method can reduce the giveaway by 10 – 12 percent compared to traditional solutions. Depending on product type, size, and weight, the robot can process and pack 40 – 50 products per minute. Using cascading multiple robots the total input of the machine can be increased in a linear ratio to the number of robots.
The modular machine design is based on a PacDrive automatic solution created by ELAU, a subsidiary of Schneider Electric. A central PacDrive controller with motion control, PLC, and robotic functions controls all mechatronics of the machine as well as the robot or robots. Further the controller makes calculations to determine the weight of each product. The robots communicate with the controller via SERCOS. The speed-controlled conveyor belt drives are directly connected to the PacDrive controller I/O, and so are all other sensors and actuators, too. The control unit and the image processing system are linked to the controller via Ethernet.
All ELAU PacDrive P4 pick-and-place robots are equipped with iSH servomodules. iSH servomodules are integrated drives, which combine servomotor and drive electronics in one single assembly. Each robot is connected to the shared power supply and the motion logic controller in a flexible design, each with only one hybrid cable and a self-configuring distribution box. The SERCOS interface, power supply, and all other motor signals are led through one single cable, using two-sided pluggable hybrid cables. Thus one pluggable cable provides the electrical and communication connection for integration of each robot into the system.
Integrated drives reduce control cabinet size
iSH technology and the absence of separate servodrives reduce the number of components needed for the robotics and the control system in the control cabinet. The only components required are the controller and the shared power supply. One major advantage of the modular machine design is that the integration of ten robots requires only three power supplies more than for the pilot version with only one robot. The robots can be integrated into the automation solution by one single pluggable cable. Additional self-configuring distribution boxes on the machine frame provide the needed number of sockets.
The software design is based on the PacDrive programming template, which allows users to map software modules to the corresponding mechanical modules on the machine. The IEC machine program was created by using IEC 61131-3-compliant Function Blocks both for the mechatronics and the robots. Each additional robot is integrated into the machine program as a software module. The vision system is incorporated using Function Blocks from the universal VisionLib library for popular image processing systems.
Regardless of the number of robots involved, the machine can be equipped with the usual options: A check weigher double-checks the package weight, if needed, and a printer applies product data to the package, enabling batch tracing.
Mr Henning Ingemann Hansen believes that there is a big international market for above machine design. He says: “The elimination of transfer steps between the processing steps saves time. Moreover, the system is extremely compact relative to its output. According to our calculations the investment costs for such a machine will be amortized after only 1 -1½ years”. Cabinplant A/S is currently designing a system to process sardines for a customer in Greece. Plans for this system include 10 P4 robots, which will be sufficient for a throughput rate of 400 – 500 products per minute. “This will give an output of 80 – 120 cans per minute, depending on the fish size” says Mr Hansen.
Modular expandable performance
As Mr Hansen explains, an expansion of the system to 10 robots is not a problem from a technical point of view. “The machine is completely modular, not only speaking mechanics and software, but also with regard to the electronics. As the robots have iSH drives, expansions to the system need no additional wiring in the control cabinet. Operation with 10 robots requires only another few power supplies. We designed the PacDrive program structure-based software to be modular right from the start, enabling flexibility as to the integration of more robots.”