This presentation was made at the 2019 NAFEMS World Congress in Quebec Canada
Joints such as hinges are present in many areas of our everyday life. Even before reaching our work place in the morning, subconsciously we use hinges of various types when we enter our bath room, open cabinets or get into the car. A typical and rather demanding application of furniture hinges are kitchen cabinets, as shown in Figure 1. Customers expect a large choice of different hinges to choose from, each suitable for a specific application, featuring an attractive exterior and a high durability. Various cabinet dimensions, a wide range of door sizes and a large selection of handle bars and materials need to be covered. At the same time, hinges should be easy to install and convey a pleasant sensation while in use.
When designing a new hinge, two main functions need to be considered: First, the cabinet door needs to close autonomously once a specified closing angle has been reached. Secondly, a damping mechanism capable of large closing velocities is required. Obviously, these requirements are not independent: The power of the self-closing mechanism affects the design of the damping-mechanism and vice-versa.
While the design of a closing-mechanism is rather straight forward in terms of technical aspects, such as force and stiffness of the spring and the shape of the integrated cam, the design of a damper is far more challenging: First of all, the damper cannot be designed independently, as its behavior strongly depends on the closing-mechanism. Due to the smallness of some parts the functionality of typical hydraulic dampers is very sensitive to manufacturing tolerances, which need to be factored in. Furthermore, the amount of energy that needs to be absorbed varies greatly. It is given by the kinetic energy of the cabinet door, which in turn depends on the closing speed and on the total weight of the door, including all attached equipment such as kitchen utensils.
Due to these challenges a design process that exclusively relies on physical testing is very expensive, both in terms of costs and time. Thus, a CAE-based alternative is established: By using an MBS-model the behavior of the door including the hinges is reproduced, and the damping-characteristics can then be explored in the virtual world. Moreover, due to the underlying relationship between the damping-force and its geometry not only the damping-characteristics, but more importantly the actual design of the damper is obtained as well.
This presentation outlines the principal setup of the multi-body dynamics (MBD) model and focuses on its application. An automated workflow using this model has been implemented to derive the optimal design of each particular damper.
|Date||18th June 2019|
|Organisation||Julius Blum GmbH|