Flexible e-chains and cables for grippers in BD Rowa picking systems

Long service life of the cable guidance with 180° bend radii and multidimensional movements

Many chemists no longer get medicine fetched from drawers, but rely instead on automated warehousing.  In these cases, there is always an automated storage and order picking system behind it - and often it is one from the company CareFusion | Rowa. The company based in the Eifel has been a pioneer in the field of chemist's shop automation since 1996 and is now well established in the market. The chainflex cables and energy chains from igus supply energy and signals reliably to the highly mobile grippers.

Profile

  • Requirements: Cable solution for multi-dimensional movements of the energy and signal supply with special requirement profile, S-shaped movements, bend radii of more than 180°, long service life with minimum noise development.
  • Industry: Mechanical engineering, chemist's warehouse
  • Success for the customer: Individually created solution for cables and cable guidance, tests in the igus laboratory, particularly flexurally resistant cables without core ruptures and with minimal wear, particularly compact type
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Vmax order picking system with chainflex The automated storage and order picking has been implemented – thanks to Rowa – in the chemist's shops. The latest generation Rowa Vmax system.

Problem

In 1996, the newly founded Rowa Automatisierungssysteme GmbH launched the first fully automated storage and order picking system for chemist's shops. In the meantime, Rowa has installed more than 5,000 of these systems; and with around 3,000 installed systems in Germany, Rowa has even secured a market share of around 70 percent. From the chemist's point of view, automation saves a lot of space and even more time. It also creates the right conditions for a reduction in inventory levels and thus capital commitment.
The gripper system is the heart of the machines. The latest generation of the patented HD-Multi-Picking gripper can simultaneously move up to eight packages - of the same variety or even different ones.  In the narrow aisle of the storage system, two gripper systems can work in parallel and without collision, which doubles the picking performance and allows the grippers to make very complex coordinated movements to store and retrieve the desired goods as quickly as possible.
However, the high freedom of movement also includes high requirements for the energy and signal supply as well as the cables. These have to follow the multi-dimensional movements without any problems, which places significantly greater demands on the energy chains and cables than in most other automation applications. For example, the cable guidance must allow S-shaped movements with very tight bend radii and be able to stretch in the opposite direction.
Despite the heavy loads, a long service life was a particular core concern for the customer. And a no less important development goal was to keep noise emissions as low as possible. The increased service life was not to be at the expense of noise generation.

Solution

Today, Rowa uses the igus product range for energy and signal supply systems as well as cables.
Even though the chainflex cables were explicitly developed for very high stresses and intensive movements, the systems represented a special requirement profile.  The frequent bending beyond a bending angle of 180 degrees and the simultaneous use of a very small radius puts a lot of stress on the cables. In order to find the optimum solution, Rowa provided the igus team with two gripper systems.  Endurance tests were run in the igus laboratory and the electrical specifications of the cables were tested - with the result that in some cases different core cross sections were chosen. The focus was clearly placed on the service life so that the systems can run maintenance-free.
Specifically, chainflex cables of the CF10 type are used as energy and control cables as well as cables from the CF11 series as data cables. In all series, according to the tests, the conductors have an extremely bending-resistant design and construction, the special stranding ensures a lasting flexibility in multiple dimensions without core ruptures and with minimum wear. In some applications, where the cables have extremely small radii, a control cable of the CF99 series with an alloy conductor is used, because even smaller radii are now possible.
For the energy chain, which is subjected to the same stresses as the cables, the radius of the chain had to be individually adapted due to the installation space. Here, the igus designers have done detailed work to achieve maximum availability.  The E2 series energy chains are used here in enclosed and open design on the gripper and the 2500 series for the longitudinal travel of the complete gripper system along the racks.
"We prefer to use high-quality standard components - not only for cost reasons, but also because of the availability. We have concluded service contracts for most plants and are therefore in such a position that no standstill occurs. "
 
Stephan Brokonier, Team Manager of Electrical Design at CareFusion | Rowa
Gripper with energy chain The grippers are characterised by special mobility and can grip up to eight packages at once.
energy chain Chain and cables accomplish maximum performance in the Rowa grippers. Here a drylin lead screw module from igus is also used.

Further collaboration between Rowa and igus

This development cooperation was not the first for igus and CareFusion | Rowa. Andreas Pauli: "For many years we have been working together with igus and we appreciate both the accuracy with which our concerns and requests are processed, as well as the flexibility and speed, for instance, when performing tests."  Consequently, we currently have further development projects. One relates to a new series of sorters that identifies and separates the medicine packets to be stored and assigns them a location for storage. Here movable cameras are used – and igus has the appropriate expertise in data cables used in image processing applications. In matters of bus technology CareFusion | Rowa is planning the next steps and can procure from igus the appropriate flexible cables, for example for Ethernet and other data standards. A significant advantage here is that due to the variety of qualities of the bus cables, one can make exactly the right choice in order to get exactly the cable that is needed.
Another topical issue at present for CareFusion | Rowa is the qualification of plants according to the North American UL/CSA standards. By belonging to CareFusion, additional opportunities are opening up for the Rowa systems in the American market, which requires particular approval of cable types. Andreas Muckes: "The main focus of European standards is on the materials used and wall thicknesses, but the UL/CSA follow a different approach and focus on the flammability of components. This requires new tests and documentation tailored to them. " The used igus components cause little additional work in this task: they are already available  as a UL/CSA certified solution.
Storage system with energy chain The igus energy chains and cables are also used in the fully automated Rowa ProLog storage systems, which automatically identify the medicines and specify a storage location.
chainflex The chainflex cables have been developed from the ground up for mobile applications. Therefore, the special stranding is part of their design features.