Rational Barrel handling in chemical companies

Drastic reduction in truck unloading times with mobile vacuum lifting device which can be driven onto semi-trailers.

Barrels and similar containers made of sheet metal or plastic are still widely used in many sectors of industry for the packing, transport and handling of liquids and powders. This is particularly true of the chemical industry, which transports its raw materials and additives in barrels.

A very good example of this is a company with more than 900 employees worldwide which produces paint and plastic additives and is one of the market leaders in this sector. The amount of chemical products which goes through its factories is correspondingly high, and most of these are transported in 216-litre barrels. This, in turn, means that the company needs large numbers of empty barrels, and these are delivered on trucks and semi-trailers. Each semi-trailer is loaded with 160 barrels, each weighing 17.8kg, which are stacked in three layers and almost completely fill the available space.

However, these three layers are possible only if the barrels are stacked without intermediate spacers or pallets. If these were used, only two layers would be possible and the number of semi-trailers, trips and personnel needed to transport the required quantities would be far higher. Although dispensing with pallets permits one additional layer to be carried in each vehicle, it also makes unloading of the barrels more difficult because each single barrel has to be lifted from the stack, moved out of the semi-trailer, transported to the storage location for the internal material flow and, finally, moved from there to the filling station. In the past, this was done by 3-4 persons: the first removed a barrel from the stack and passed it down to the second person, who rolled it down a gangway to the third person. He then rolled the barrel to the lading point of a conveyor belt, where the fourth person received it and placed it on the conveyor belts of the internal material-flow system.

From inefficient hard work by four men...

 When the management decided to erect a new building and reorganize the production in the in-house logistics, the planning work for the future material flow resulted in the idea of flexibly unloading barrels from semi-trailers with the aid of an industrial truck equipped with a barrel gripper, BYK looked for a solution which would take the various requirements into account. The hardest task fell to the application engineers at Schmalz (represented by Millsom Materials Handling in Australia & New Zealand), since the vacuum gripper system had to be designed such that it could safely grip, lift, transport and position between three and seven barrels at once, using only a single gripper system. A further problem was the fact that the three layers of barrels left a space of only 250mm between the top ends of the upper barrels and the roof of the semi-trailer, which meant that the overall height of the gripper could not exceed 180mm. Using components from their standard range of VacuMaster vacuum lifting devices, the engineers developed a suitable vacuum lifting device for a maximum load of 140kg, which was then mounted on a suitably adapted electrically powered, manually guided lifting truck of the Type Ameise EJB 16. The gripper system comprises two cross-beams, each with seven suction pads, where the suction-pad positions can be adjusted on the cross-beams to the best position for gripping the barrels.

...to automate barrel handling with lifting truck and vacuum lifting device

The suction pads are made of the hard-wearing but flexible material NBR (buna N) and adapt themselves well to the surface of the barrels. Each pad has a diameter of 160mm. In order to ensure quick and safe gripping of one or two rows of barrels, the suction pads are mounted flexibly, on spring plungers with a length of 40mm and on flexible joints. This combination can compensate for varying barrel heights and also permits tilted barrels to be gripped securely. It also permits suction pads which happen to be placed on the rim of a barrel to be withdrawn in order to prevent them from being damaged. The 2 x 7 = 14 suction pads on the two cross-beams are divided into five vacuum circuits so that the vacuum can be disconnected from pads which are not in contact with a barrel. This arrangement also ensures that the barrels, which are often stacked haphazardly, can be gripped and transported reliably and safely. The five separate vacuum circuits permit the following gripping configurations: one row of four barrels and one row of three; one row of three barrels and one row of four; one (front) of three barrels; one (front) row of four barrel. The vacuum can be switched off in all five circuits to release all gripped barrels. The vacuum circuits are controlled by the driver of the industrial truck from a multi-function operator panel on the truck. Releasing of the barrels requires two-hand operation.

An optical display on the truck shows which of the suction pads are actually in contact with barrels. The vacuum is generated by a robust, maintenance-free vacuum pump followed by a large-volume vacuum reservoir to permit rapid evacuation of the gripper system. The VacuMaster vacuum lifting device is equipped with many safety elements to ensure maximum safety under all operating conditions. These include the optical indication of the suction-pad coverage, two manometers for monitoring the vacuum levels, an electronic (audible) warning device which sounds in the case of a low vacuum or a power failure, two-hand operation for releasing the barrels, and a safety inspection in accordance with the applicable regulations before it leaves the factory. The very flat design of the cross-beams permits reliable and safe gripping of barrels in the top layer. The adjustable limit switches of the lifting truck permit rapid and damage-free insertion of the lifting device into the available space.

Maximum flexibility and safety thanks to an intelligent suction-pad system

The barrels can be stacked with either end at the top, and the operator does not need to worry about the positions of the bungholes. The adjustable proximity switch for stopping the lifting motion ensures that the device automatically detects when the suction pads come into contact with the barrels. This prevents damage to the lifting system and the barrels and means that the operator does not have to take care not to press the suction pads too hard against the barrels. Once the barrels have been gripped, the truck is moved from the semi-trailer to a conveyor belt.

Here, the barrels are placed on a bench, labels are attached to them, and they move via a roller conveyor to the filling station. The success of this vacuum-based barrel-handling system has by far exceeded the expectations, the foreman in the area raw-materials stockroom/production says: "We now need only one person to unload the semi-trailers, rather than the 3-4 persons previously needed. The time needed for this has been reduced by up to 75%, depending on how far we have to move the barrels. The new ergonomical and safe barrel-handling system has eliminated the risk of injuries caused by incorrect lifting which frequently occurred in the past. With only slight modification, the system can also be used to load semi-trailers, permitting further rationalization effects. And last but not least, the technical benefits are accompanied by economic benefits, since the investment in the mobile vacuum-handling system for barrels paid for itself within only six months".

For further information visit Millsom Materials Handling at http://www.millsom.com.au