igus® bearing technology in automated blister centre
 

Profile

• What was needed: drylin W -profile guides and drylin high helix thread with plastic nut
• Requirements: Maximum service life in 24/7 operation, low abrasion due to conveyance of unpackaged medicines, complete lubrication-free linear and curved guidance, tight curve radii, minimised vibration and low noise
• Industry: Medical technology
• Success for the customer: The material combination of drylin W and iglidur J ensures maintenance-free and wear-free operation of the circulation system over a long period of time. This is confirmed by the tests performed so far by Rowa with the first prototypes of the circulating system.

Problem

Several hundred patients, who spend seven days in hospital on average, have to be given the correct medicines 24/7. This is a task that every hospital pharmacy has to master. It is a challenge involving considerable effort in terms of organisation, administration, personnel and checking techniques. Private pharmacies also face the challenge of providing care facilities and elderly people with a large number of medications according to increasingly individualised medication plans. In future, this effort can be simplified considerably and made safer - with the new Rowa Dose system, developed by Becton Dickinson Rowa Germany GmbH.
 
Prerequisite for the fast and error-free delivery of the medicines to the blister unit is a "fast" circulating system, which must also be characterised by a high degree of availability. The list of requirements specified by the Rowa design engineers therefore included a service life that was to be as long as possible with the machine operating 24/7, as well as a low degree of abrasion, given that the downpipes transport medicines that are not separately packaged.
 
For the same reason, a completely lubrication-free linear and curve guidance system was required. Further important selection criteria were not only the ability to move through small curve radii but also to keep friction as little as possible in order to decrease the amount of drive energy needed, minimise vibrations and keep the noise level low.
 

Solution

Not for the first time in the development of Rowa systems, the solution was found in igus' modular system for bearing and drive technology engineering. For horizontal guidance of the down pipes, drylin W profile guides made of hard-anodised aluminium are used, albeit in the form of an extra wide and extra tall version that can absorb greater tilting forces and always ensures stable guidance of the down pipe.  igus has now incorporated this version into its standard range of products.
 
A "real" custom-made solution is used on the narrow sides of the circulating system. Here, 180^o-curves with a radius of 80 mm had to be implemented. This is only possible with customised machined parts that igus makes specially for this application. Moving through tight curves also necessitates specific plastic sliders that maintain stability during movement into the tight curve even at high speeds.
 
The individual design also made it possible to implement a further special function: on the narrow sides, the guides can be opened in order to replace individual bearings. This presupposes a production with a very high degree of precision because the bearings pass over this section every time - and they do so at a high frequency as several hundred guide elements of the type drylin W 10 with liners made of the high-performance maintenance-free polymer iglidur J are built into each Rowa Dose system.  

drylin W profile guides guide the down pipes horizontally. The extra wide profiles were initially a special size but have now been incorporated into the standard range of products.

A three-digit number of these guide elements is built into each Rowa Dose system - with two maintenance-free drylin W linear bearings for each element and liners made from the high-performance polymer iglidur J.

The heart of the Rowa Vmas system is the patented "Picking Head". In the gripper system the drylin high helix thread with plastic nut is used.  It ensures precise linear movement on the shelf.