Simulation-driven Design in the Development of High-performance Tools - Intrim Report

Developing a product to attain market maturity is a long process. Within this process it is important to make the right decisions, especially when conflicting goals arise. These are typically defined by ambitious product requirements in partly competing dimensions.

In the development of electric tools and accessories, such as those produced in a mechanical engineering enterprise like Hilti, lightweight construction, long-life cycle, robustness, high performance and low costs are typical targets. Regarding so called combis and breakers (see Figure 1) there exist corresponding key values, which help the customer to assess the product: single impact energy, weight, rated power, operator’s comfort, vibration level. The implication of these user oriented requirements present the most challenging task for development in generating a lightweight design having high performance and robustness. The task is especially demanding due to high dynamics inherent in the tools, causing very complex impact loads.

Combis and breakers achieve their huge performance from the so called electro-pneumatic hammering mechanism: ‘the heart of the tool.’ It consists of several pistons that achieve high velocities and a pneumatic spring which generates high pressures. The interaction of these different machine parts leads to very high stresses for the tool components, requiring a particularly robust design.

In this project we will perform a case study of a simulation based design, where we will pick up a real-life problem from industry, the so called chuck of a combi-hammer. As mentioned above, throughout its entire life time the chuck is frequently loaded by high impact. During our development process we have to ensure that the chuck subassembly reaches the lifetime target in a robust and reliable design. We will also practice team-based strategies to master all the unexpected difficulties arising in any complex collaborative development process.

The structure of the workshop will be a sequence of short introductory lectures, student’s research and intensive discussion phases.