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Automated overhead conveyance of wood board bundles

27.10.2020 von Achim Altmann

An important part of the highly modern production is the internal material transport between the individual production lines. In total, seven automatic cranes from ALTMANN are operated here.

The automatic cranes comply with the following performance data:

Lifting capacity: up to 12,500 kg
Crane speed: 120 m/min
Trolley speed: 60 m/min
Lifting speed: 40 m/min
Positioning accuracy: +/- 1 mm in each axis

Warehouse crane

Automatic warehousecrane

Illustration 1: Automatic crane for wood stack transport


On a storage space of nearly 6,000 m2, chipboard bundles with lengths from 2,800 mm to 5,800 mm, widths from 1,830 mm to 2,825 mm and heights from 100 mm to 1,500 mm are stacked up to a level of 11 m fully automatically.

Orders are transmitted to the crane control via a higher-level process control system, where they are double-checked and processed. Of course, this takes place within fractions of a second.

These are the crucial requirements for the automatic crane system:

- Safe picking up of the different chipboard stacks
To avoid faulty conditions in stock accounting, the stacks are measured when being picked up and compared to the order data.
Deviations are accepted up to a certain tolerance and taken into account when storing and removing.
Outside the tolerance, a corresponding deviation message is transferred to the process control system.

- Reliable 24-hour operation
An efficient production must be operative around the clock and seven days a week. If the automatic crane failed, the whole flow of goods in the factory would come to a standstill.
To prevent that from happening, the automatic crane is designed for high availability in all assemblies.

- Highest precision when stacking
The completely filled warehouse is not accessible anymore for people and machines due to the optimum use of space. Faulty stacking or unstable towers, in the worst case even overturning towers, would make the warehouse unusable for weeks.

The automatic crane must be capable of compensating all tolerances of the manufacturing process, from the production of the single board through bundle stacking up to transportation to the point of transfer in the warehouse. At the same time, positioning accuracy must meet the highest requirements in order to guarantee a faultless and accident-free handling of the chipboard bundles.

- Flexible adaptation to changed stack towers
Depending on storage duration, the towers may settle down by some centimetres. When removing items from stock, the gripper of the automatic crane must not approach the position it used when storing. It must rather be able to recognize these changes and respond adequately.

- Integrated warehouse management system
This system is indispensable for order verification. It is necessary to avoid under all circumstances that collisions occur because a storage location is already occupied, and the stack must not be deposited in the air.



Automatic crane clamshell bucket motor gripper

Illustration 2: Automatic crane clamshell bucket motor gripper

Performance data:

Lifting capacity: 12,500 kg
Crane speed: 120 m/min
Trolley speed: 60 m/min
Lifting speed: 40 m/min
Lifting height: 16,000 mm
Positioning accuracy: +/- 1 mm in each axis
Gripper volume: 14 m3
Output: 300 m3/h

A chip silo with a capacity of approx. 18,600 m3 supplies the required raw material to the production facility.

The automatic crane stores the material delivered by truck in the storage silo and removes it as required into a container, where the further transport is done by a screw conveyor.

Due to various emptying programs to be defined by the control station, it is possible to empty the silo sectionally and thus to prevent smouldering fires caused by pressure and friction.

The control on the automatic crane is equipped with a self-releasing fire-fighting system.

Electricity and data are wired to the gripper via a reeling energy chain which is driven by a motor and synchronised with the hoist. What makes this even more remarkable is that the synchronisation of the hoist always has to consider the changing diameter of the energy chain when regulating!

The hoist design and the gripper suspension have received particular attention. The gripper operation is the most difficult application for a hoist and a rope drive.
By means of four separately controlled rope drums which are synchronised exactly to the millimetre, a frame with flexible gripper suspension is lifted by the hoist. This enables balancing of cross forces and twisting when the gripper is closed. The hoist ropes are thus considerably discharged and diagonal force is avoided.


Double rail overhead trolley

Illustration 3: Automatic crane Shuttle for wood stack transport

Performance data:

Lifting capacity: 12,500 kg
Crane speed: 120 m/min
Trolley speed: 60 m/min
Lifting speed: 40 m/min
Positioning accuracy: +/- 1 mm in each axis

The internal transport of board bundles between the individual production sites or to the buffer locations is made via five shuttles in total.
Where they act in the hazard zone of people, they are equipped with a multi-part fall protection system which secures the bundles during travelling and lifting.
The gripper with fall protection must grip and handle the different board sizes as safely as the automatic crane in the warehouse.

For the operability of the automatic shuttle, the permanent communication with the higher-level process control system is extremely important. Here, the integration into the complex safety technology of the rest of the factory is of particular significance.


Altmann_Automatic Crane Visualization User Interface

Each facility is provided with a visualisation which on the one hand supplies the user with all important status information and on the other hand directs the maintenance staff quickly and purposefully. It offers all options for installing and adapting the automatic crane.

The user interface is three-lingual in order to allow all participants to call up information in their native language. Of course, all visualised information is also transmitted to the process control system.