The robot that can handle any drink
Jointed-arm robot palletizes beverage trays
At the Carlsberg brewery in Sweden, a six-axis jointed-arm robot stacks trays
of PET bottles. Although the robot is a KR 500, the largest KUKA robot, it takes
up significantly less space than the layering palletizer that was used
previously. What is more, this heavy-duty robot – with a load-bearing capacity
of 500 kg – can be reconfigured quickly for new bottle sizes by making small
program changes. Thanks to its high degree of flexibility, the KR 500 can
“handle” any drink.
Founded in 1847, the Carlsberg group has a range of products which includes the
beer brands Carlsberg and Tuborg, drunk in over 140 countries. The headquarters of
today’s Carlsberg A/S are still at the same location in Copenhagen where its first
brewery building was erected over 150 years ago.
In May 2000, Carlsberg and the Norwegian company Orkla ASA merged their
breweries to form Carlsberg Breweries A/S, with the Danes holding 60 percent of the
shares. Carlsberg Breweries is one of the world leaders in the brewing industry. This
is borne out by annual production of 60 million hectoliters of beer, net sales of more
than 30 billion Danish kroner per year, and a workforce of over 29,000.
Carlsberg Sverige AB, a subsidiary of Carlsberg Breweries, was formed in February
2001 through the acquisition of the Pripps and Falcon breweries. At that time Pripps
was already the most important Swedish brewery, whose products included the bestselling domestic brand of strong beer, Pripps Blå. The Falcon brewery, on the other
hand, had received a license to brew Carlsberg beers back in 1985. Carlsberg
Sverige produces beers of various strengths, modern soft drinks, Pepsi-Cola and
mineral waters, including the renowned premium brand, Ramlösa. The largest plant
and headquarters is in Bromma, west of Stockholm. Here the company produces
191 million liters of beer and soft drinks annually, thus meeting 16 percent of the
Swedish demand. The beverages are filled into glass bottles, disposable and
returnable PET bottles, and cans.
40,000 bottles per hour
In 2001, the then Pripps brewery invested in a production line for disposable PET
bottles. This line operates on two levels and has a capacity of 40,000 half-liter bottles
per hour. At present it can fill 34 products into bottles ranging from 0.33 to 2.0 liters.
The spectrum of beverages encompasses “still” and carbonated soft drinks, beer,
and fruit juices which are filled while hot – a diverse range of products which the
company plans to extend still further.
The manufacturing system operates in two shifts. After the bottles have been packed
on trays, they are transferred by means of a spiral conveyor to a height of about
three meters, where they are fed on buffer segments to the KUKA KR 500 heavyduty robot. This six-axis jointed-arm robot, as well as the complete production line,
from the arrival of empties right through to shipping, was supplied by KHS
Maschinen- und Anlagenbau AG, Worms, Germany. KHS, which specializes in the
beverage industry, is a system partner of KUKA Roboter GmbH, Augsburg,
Germany. The KR 500, commissioned in November, 2001, replaced a layering
palletizer.
Flexibility in a minimum of space
The robot, supplied at customer request with a light blue paint finish, combines a
markedly reduced floor space requirement with the advantage of quick adaptation to
new bottle sizes by means of simple program changes. Other remarkable features of
the six-axis robot are its long reach and the enhanced flexibility provided by its
custom-tailored gripper. The KR 500 also stands out for its short cycle times,
positioning accuracy, low maintenance requirements, easy operator control and high
availability (well over 95 percent). Its load-bearing capacity of 500 kg is necessary in
this case, since entire layers are always palletized at a time. With a weight of just
2,350 kg (light in relation to its payload), the heavy-duty robot is also easy to
integrate into manufacturing systems. This is equally true for operation in moist
environments, since the KR 500’s wrist has a protection rating of IP 65.
The trays of PET bottles are fed to the robot by means of three conveyor segments
and a roller table. They are distributed onto two conveyors in accordance with the
specified stacking pattern, i.e. the controller counts the trays and causes them to be
rotated if necessary. A pusher them moves them from the table onto the so-called
“roller carpet” of the robot gripper. The KR 500 centers the trays and holds them
securely while moving them. Depending on the size of the bottles, the robot picks up
either ten trays with 3 x 5 bottles each, or nine trays with 6 x 4 bottles each. In
addition to these usual packages, the six-axis machine occasionally handles smaller
ones with 2 x 4 or 2 x 3 bottles. The number of layers is likewise based on the size of
the bottles (maximum of six layers for 0.5-liter bottles), while the stacking pattern is
varied continually in order to increase stability. The specific program is selected by
the operator.
Gentle handling
The KR 500, which can also pick up smaller film-wrapped packages without trays,
sets the bottles gently down on Europallets or half pallets. To do this, it retracts its
gripper’s roller carpet. The trays are centered on the pallet by an external axis, which
is also guided by the PC-based KUKA KR C2 robot controller. If necessary,
cardboard slipsheets are inserted by an automatic external device. After leaving the
robot area, the pallets move along a roller conveyor to an automatic film wrapping
device. Half pallets are separated before wrapping, then brought together again and
placed on a Europallet waiting on a lower-level conveyor. The two half pallets are
positioned in a station which holds them in place laterally until the Europallet rises to
meet them. Finally, the pallets are picked up at two removal positions using forklift
trucks and taken to the warehouse.
Stacking is faster than filling
About a year before the KR 500 heavy-duty robot, KHS had supplied two KR 350s to
Carlsberg Sverige in Bromma. Since 2000, KHS has installed a total of 36 KUKA
robots in Denmark, Norway and Sweden. Independently of this, the company has
also installed KUKA PC-based controllers for use with its own in-house robot arms.
Commissioning of the KR 350s took place in February 2001. These robots are
components of two filling lines for 0.33 and 0.5-liter cans, which Carlsberg uses
primarily for beer in various-sized packages. Each of the two robots has a loadbearing capacity of 350 kg, and palletizes 48,000 cans per hour in three-shift
operation while also inserting the necessary number of slipsheets. The potential
stacking capacity of the KR 350s is 15 percent greater than the maximum output of
the lines.
The trays of cans are transferred to the robotic cells by means of special belt
conveyors. These “pack routers” are equipped with mechanical devices which rotate
or shift the trays into the positions called for in the programmed layer pattern. The
trays are then brought to the pickup position of the corresponding six-axis robot,
where they are centered. There, the KR 350 picks up the trays using its suction
gripper, which was designed by KHS and weighs 200 kg. It also uses this gripper to
handle the slipsheets. Each can is held by a separate suction cup. Using an
integrated vacuum monitoring system, the controller verifies that all of the gripper’s
suction cups are generating sufficient vacuum. Whenever the vacuum drops below
the specified tolerance limit, the KR 350 stops automatically and a message
indicating the fault appears on the monitor of the operator panel.
Directed by a KUKA KR C1 controller, the robot sets the cans down on half pallets,
which in turn rest on a Europallet. Here too the pattern is varied in each layer in order
to provide greater stability. Following palletization, the half-pallets are separated,
wrapped, reunited on a Europallet, and brought to the warehouse by forklift trucks.
Carlsberg either operates both lines with the same product simultaneously, or with
two different beers and/or package sizes.
Flexibility as insurance for the future
Thanks to their flexibility, the filling lines installed by KHS for PET bottles and cans,
including the robots employed in the lines, have been built with the future in mind,
thus enabling the user to respond quickly to changing market conditions.
This is of particular importance given the complicated nature of the Swedish beer
market. Despite high taxes on beer, breweries there are trying to tap every
opportunity to attract customers to domestic brews. Importation of beer by private
individuals amounts to about a million hectoliters per year, and if the breweries were
to succeed in minimizing these imports they could achieve growth of up to 20
percent.
Author: Jürgen Warmbold, freelance technical journalist, 27327 Martfeld, Germany