Des ponts bipoutre ABUS en Suède dans la cimenterie "Dahlgrens AB"
You might be excused if you think of giant lego pieces when you see the concrete blocks made by Dahlgrens Cementgjuteri (www.dahlgrenscement.se), a company dealing in precast concrete at Skellefteå in the far north of Sweden. The same logic is actually used for these concrete blocks as for lego making it easy and affordable to build wall elements. The family-run company was founded in 1935 by John Dahlgren and employs 30 staff today. Other precast concrete elements made by Dahlgrens are wells, pipes, retention walls, and elements for walls and bridges. Customers include the building industry, municipal enterprises, and the Swedish ministry of transport. Pipes are produced with diameters between 225 and 2000 mm. Well elements may reach maximum diameters of 3500 mm. Dahlgrens Cementgjuteri AB together with other companies of the sector forms part of a developing association whose aim it is to promote product development and to open up new distribution channels for the sales of concrete products in all of Sweden.
A further production hall with a surface of 760 m² and a height of 7.8 metres was built and brought into operation in order to be able to build yet larger elements for wells, walls, and bridges. The production of the pipe elements remained in the existing building where an old ASEA crane was replaced by an ABUS single girder EOT crane type ELV with a load capacity of 5 tonnes. The new production plant saw two double girder EOT cranes type ZLK installed with spans of 16.85 metres and SWL of 12.5 and 20 tonnes respectively well able to handle the much larger and heavier elements.
All three cranes are operated via radio remote control. The crane user is able to keep an eye on cranes and loads while being at a safe distance thanks to the radio remote controls. A large LED load indicator informs the crane user reliably of the loads suspended in the hooks even at greater distances: The load indicator is visible from up to 50 metres distance depending on the visibility on site. Transporting filled concrete casting buckets requires very sensitive crane and trolley movements and very smooth transitions when changing between slow and fast travelling speeds. This smooth transition between two speeds is achieved by using the ABUS smooth starting unit AZS and the smooth switching relay SU-2. A patented process in the switchover relay detects automatically the right moment to influence the transition of the fast travelling speed onto the low one or from the fast travelling speed to zero in such a way that load sway is minimised, an essential prerequisite for the transport of sensitive or large goods. Individual acceleration ramps may be set in the device in accordance with the application.
Project planning and development, installation, and commissioning of the cranes were carried out by the Swedish subagency of ABUS, the company CARLHAG (www.carlhag.se) at Luleå.