Tree trunk gripper with dynamically high load bearing Wippermann chains
The first step in the paper processing industry is the processing of wood as a raw material. In order to be able to load wood as safely and efficiently as possible, several manufacturers of construction machines have specialised in the handling of tree trunks.
After felling and removing the branches, the trees are then transported or stacked for further processing. Special machines with gripper mechanisms are used for this purpose. For this application, the chains must loop around the entire tree trunk packages, and secure them safely.
The Wippermann leaf chain (series U), which has been designed for the highest loads and strains, is used for loading wood by means of special machinery. Our leaf chains are mainly used to fixate the upper part of the tree trunk package. Due to smart kinematics, the force affecting the gripper mechanism is optimally used. Thus up to 15 tree trunks can be safely taken up at the same time.
Since no trunk is like the other, the forces acting on the chain are very different. The Wippermann leaf chains employed here must therefore have sufficient load reserves.
Contrary to the standard leaf chain with press fit on the outer plates and sliding seat on the inner plates, U-series leaf chains have a sliding seat on every plate. The plates are fixated by special washers. This Wippermann construction has the advantage that the load on the plates is distributed more evenly, which improves the dynamic behaviour of the chain considerably. This construction increases the dynamic life cycle of the leaf chain by up to 30%.
Apart from the constructive characteristics of our chains, the quality of the materials matters a lot. Pins and plates of our leaf chains are made of high-quality steel grades. In order to ensure consistent quality and stability of the different chain components, we rely on continuous process monitoring during heat treatment to control final strength and ductility.