ResearchProject Area A
Subproject A5

Subproject A5 Disassembly in the Regeneration Process

Disassembly is a symptomatic contributor to uncertainty in the regeneration chain. Uncertainty is caused by product property changes, for example unknown solidification in the assembly joints, which is quantified in the sub-project A5 for planning disassembly forces. Solidification states, which are assigned to product loads such as operating hours, are learned by a model-based process. Furthermore, the states are decoupled from the product properties to enable product-independent application. The adaptability of the process is addressed using a predefined impact procedure and a corresponding control system, which is part of the whole workplace concept including handling operation.

MOTIVATION AND OBJECTIVE

The disassembly process in the regeneration chain of a turbine blade

Disassembly is a fundamental difference between new production and the regeneration of complex capital goods. In order not to cause additional damage to the components, resulting in a higher repair effort or, in the worst case, in scrap, disassembly has to be performed as carefully as possible. An adaptable disassembly process is used to achieve a maximum component protection, despite an unknown product condition. In contrast to assembly, where joining tolerances are known and therefore joining forces can be determined, disassembly does not allow the limitation of the required disassembly forces due to product stresses during operation, such as thermal or mechanical loads. Particulary, the high-pressure turbine considered in the research project, works with high stress during operation. Thus, after operation the connection between the turbine blades and disk is solidified to an unknown high degree. For disassembly planning, unknown disassembly forces mean that disassembly times and dimensions of the tools can not be accurately estimated.

CURRENT RESEARCH AND OUTLOOK

A method for determining the disassembly forces is developed based on experimental and numerical investigations. Disassembly planning parameters such as tool forces or process time can be derived from the forces. Based on a mechanical modeling of an assembly connection, disassembly forces are handled in a learning process and assigned to product properties such as operating hours, geometric properties and operational loads. On the basis of mechanical modelling, the design properties of a product are decoupled, so disassembly forces can be used for product variants, which leads to an efficient and flexible disassembly planning.

The disassembly process is realized by a piezo stack actuator, in order to generate targeted impacts on the solidified joining partners. The surge amplitudes and frequencies as manipulated variables are implemented from the disassembly planning as feedforward control. With the conceptual implementation of a disassembly workplace, including secondary processes such as handling, a complete disassembly process is created.

Robot-assisted disassembly of turbine blades with an impact tool

PUBLICATIONS

All publications of the Collaborative Research Centre

SUBPROJECT LEADER

Prof. Dr.-Ing. Annika Raatz
Address
An der Universität 2
30823 Garbsen
Building
Room
223
Address
An der Universität 2
30823 Garbsen
Building
Room
223

STAFF

Dipl.-Ing. Julius Wolff
Address
An der Universität 2
30823 Garbsen
Building
Room
115
Address
An der Universität 2
30823 Garbsen
Building
Room
115