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25/08/2010
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A new approach to scoop insertion machine design based on a Rockwell Automation Delta robot solution is offering a contract filler reduced time and cost of product changeovers.
When powder filling equipment machine builder, Albro was approached to design an all-new system for inserting scoops into tins prior to filling with powder, the challenge was to produce a machine that would deliver the flexibility to work with over 30 different combinations of scoop and can, with virtually zero downtime in product changeovers. The solution was a Delta robot-based pick-and-place system, developed in collaboration with Rockwell Automation. It was built on Rockwell Automation's Kinematics robot control software, integrated within the Logix control platform, allowing the entire system to be set up within a single control environment.
Albro's customer, based in New Zealand, offers contract filling services to a number of companies, so the line has to be capable of working with different can sizes and different spoon sizes with a high degree of flexibility, making it viable for short run, on-demand production. This ruled out traditional approaches to machine design, where every different product combination requires reconfiguration of the machine.
Recognising an increasing trend towards robotics in packaging applications, the engineers at Albro were keen to discuss a robot-based solution, and called in the Rockwell Automation global OEM technical consultancy (GOTC) team to explore the viability of such a system. The GOTC team provides a unique resource for machine builders, with over 50 highly-qualified engineers across Europe bringing vital application knowledge and best practice advice to projects, finding the best possible solution to a given challenge and helping the customer to implement that solution.
The answer in this case was to combine Rockwell Automation's newly developed Kinematics robot control software with an off-the-shelf Delta robot, allowing all the motion and control disciplines involved (robotics included) to be handled by a single programming language, in a single programming package. This offered the potential for savings in both the time and cost of development.
Delta robots, also known as spider robots, are a type of parallel robot consisting of three arms connected to universal joints at a base located above the material being moved. The speed and flexibility of Delta robots make them ideal for applications where loads are light and the move distances are short. The robot's geometry allows it to move rapidly within a three dimensional space and orient a load around its vertical axis. And the simple mechanical design results in low noise, long life, low maintenance and easier access to all moving parts.
For Albro, the primary advantage of employing such a robot was its ability to easily switch between different products – in this case the different sizes of scoop ¬– with the potential for complete reconfiguration of the line for a new size scoop at the touch of a button. This also offers reduced downtime in changeovers to different products, and reduction of the cost of the change parts that are required for traditional machinery.
Simplified integration
Rockwell Automation has made robot control much easier, with the newly developed Kinematics robot control software integrated as standard within the Rockwell Automation RSLogix 5000 software.
The Kinematics software minimizes the additional robot controllers, software and special custom function blocks that would be needed when incorporating a robot into an application. Instead, the robot motion can be programmed within the RSLogix software environment utilising the same standard motion logic that is used to program all the other motion components in the application. The Rockwell Automation Allen-Bradley ControlLogix programmable automation controllers (PACs) then handle the transformations of the standard motion commands into robot motion commands.
Rockwell Automation engineer Stuart Ashmore headed up the GOTC team engaged to work with Albro. He comments: "The traditional picture of robot integration is one of multiple programming environments, multiple languages, and some complex synchronisation logic required for handshaking on both sides, adding complexity, time and cost. But the Kinematics robot control software provides a vastly simplified solution. There is just a single programming environment, and no need for synchronisation and handshaking logic because the entire application runs within one controller."
To further simplify implementation, Rockwell Automation provides an extensive Logix application instruction library for Delta robot applications. This includes support for common application functions like pick-and-place path control, ancillary axis control, conveyor tracking algorithms, vision system interface, operator interface teach and learn, position and time-based output control. This library proved key in reducing the overall development time for the new scoop insertion machine, with Rockwell Automation and Albro engineers collaborating to design, develop, build and prove the entire machine in just three months.
In the newly developed machine, scoops are fed gently from a bulk feed hopper onto an infeed conveyor driven by Rockwell Automation's Allen-Bradley PowerFlex inverters, and are scanned by a vision system interfaced to the ControlLogix PAC. At the same time, empty cans are fed alongside using a scroll conveyor driven by Allen-Bradley Kinetix 6000 servo drives. Because the whole system is full integrated using standard networks, communications between all the control devices is seamless. This allows the PAC to track the scoops scanned by the vision system along the moving conveyor in the robot's 'pick zone'. As soon as both the scoop and can are in optimum position, the command is given to the Delta robot to pick up the scoop and drop it gently into the can.
The integrated control system also includes Allen-Bradley Guardmaster safety interlocks on the machine guard doors, giving a high level of protection to the operators. They help prevent the guard doors from being opened during normal machine operation, and provide an emergency stop signal to the machine controller should an operator try to gain access through the guard door.
Offering production speeds in excess of the 120 cans per minute, the machine also provides the big benefit of ease of changeover from one product combination to another. This is now a single-button operation on an Allen-Bradley PanelView touchscreen HMI. An operator has merely to select a given can size and scoop size from the graphical menu, and the production line automatically reconfigures itself for the new combination.
For the customer in New Zealand, all this will equate to a massive reduction in downtime and in the cost of product changeovers. "In terms of the cost of the machine alone," comments Albro sales and marketing director Ian Hillaby, "when you factor in the cost of the change parts, you only have to be looking at six different scoop/can combinations before the capital cost of the new machine falls below that of the traditional methods, and our customer was looking at over 30 different combinations. But when you factor in the cost of the downtime in product changeovers with the traditional approach, the Delta robot solution is cost-effective even at two different scoop/can combinations."
Ian Hillaby concludes: "It has been an extraordinary project. The advice, guidance and development support from Rockwell Automation has been first class, and together we have developed an enormously capable and flexible scoop insertion machine. It is a new technology approach that we have absolute confidence in supplying and supporting. If we didn't, we certainly wouldn't be shipping the first one half way around the world!"
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Author
Rockwell Automation
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