The adaptive gripper DHDG from Festo handles fruit, bulbs or other pressure-sensitive items quickly and reliably thanks to its ‘Fin Ray effect’, based on the design of the tail fins of a fish.
“If flower bulbs, soft chocolate eggs or fruit are gripped with conventional metal grippers or vacuum functions, the result is a high level of loss and damage,” says Brian Abbott, product manager, Festo. “This goes against the grain of the two central objectives of automation technology: speed and quality.”
In contrast, the DHDG bionic adaptive gripper from Festo is light and flexible. It consists of a pneumatic actuator in the form of bellows and three gripper fingers arranged in the ‘Fin Ray’ pattern of the tail fin of a fish. The basic structure is made up of two flexible bands which meet at one end to form a triangle. Intermediate stays are connected to the bands at regular intervals by articulated joints. This flexible design enables the gripper fingers to adapt to the shape of the product when pressure is applied laterally – just like a human hand, but much faster.
The adaptive gripper DHDG is manufactured using selective laser sintering. In this process, successive layers of polyamide powder are applied and allowed to harden to form a solid component. “This reduces the weight acting on the tool carrier 90% compared with a conventional metal gripper. This means that the adaptive gripper DHDG is able to grip and transport pressure-sensitive products in a more energy-efficient way,” says Abbott.
The advantages of these lightweight and adaptive bionic grippers are currently experienced by Total Systems, a Dutch company producing machines and systems for handling flowers and the world famous Dutch bulbs. The company was developing a new machine for sorting bulbs and chose the adaptive gripper DHDG to sort according to size and quality. The adaptive gripper has proven itself to be quick and efficient, improving productivity at the plant.
This bionic gripper operates on the same principle in a sorting station for chocolate eggs. The gripper fingers fully enclose the chocolate eggs without crushing them or damaging the aluminium wrapping. “The flexible design of the adaptive gripper DHDG even allows the chocolate eggs to be gripped if they are leaning to one side or are incorrectly positioned,” explains Abbott.
The Festo proportional pneumatic valve VPPM ensures that the pressure is correct; which allows individual acceleration and pressure ramps to be applied. The variable flow rates provided by these proportional valves allow the cylinder pressures to be adapted to a given production or sorting process. Everything can be connected to the robotic controller CMXR which controls the tripod robotic handling unit. The tripod moves the adaptive gripper DHDG quickly towards the chocolate eggs. “This type of robot is ideal for handling light loads at high speeds,” adds Abbott, “making it ideal for the food and packaging industry.”
The design of the adaptive gripper DHDG is a result of the innovative Bionic Learning Network from Festo. This programme is focused on learning from nature and has been the recipient of a number of design awards including the Deutsche Zukunftspreis 2010 (German Future Award) for the Bionic Handling Assistant based on an elephant’s trunk. “Through the innovations of the Bionic Learning Network, we are able to design products and automation solutions that help our customers achieve higher productivity levels, in new, exciting ways,” concludes Abbott.
For more information contact Tracy Swart, Festo, +27 (0)11 971 5560, tracy.swart@festo.com, www.festo.co.za
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