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Investigation of friction drive for night closing door

By Sissela Svärd


ASSA Abloy Entrance Systems design and manufacture automatic sliding-, swingand revolving doors. A regular revolving door is often equipped with night closing doors on the outside, which are used to close the entrance when, for example, the store or workplace is closed for the evening. This prevents unwanted guests or litter to enter the space between the revolving door blades. This Master’s thesis focus on the small driving unit that is used for driving the night closing door blades back and forth during opening and closing. The force transmission between the driving unit and the door blades is based on the friction in the contact surfaces between the different components. The dimensions of each component are very limited since the space intended for the friction drive unit is very small. In this Master’s thesis, the night closing door friction drive is studied and developed to endure the high forces that act on the components. The dimensions are evaluated by considering, for example, the Hertzian contact pressure and creep ratio. Different material- and surface treatment combinations are considered to decrease stresses and fatigue wear. Other factors, such as different profile geometries of the rollers, were considered as well, to reduce the stresses. A bearing shaft with a logarithmic profile yielded a rather good result, where the edge stresses were reduced significantly. Both steel SS 2541 with Corr-i-Dur treatment and steel SS 2940-03 with gas nitriding surface treatment had some positive effects on the fatigue life. Literature studies and numerical finite element simulations were used to draw conclusions about the night closing door friction drive. Practical tests were also performed, but due to the Covid-19 pandemic the planned extent of these tests unfortunatly came out very limited.The door blades in an automatic door can be driven back and forth by taking advantage of the friction between components. Similar to a train on a track, cylindrical shafts and rods can be combined and used as a transmission system for moving the door blades in horizontal direction. This concept can be used when driving the night closing doors placed on the outside of a revolving door. However, due to high loads and high constraints on the dimensions, it is easily worn out and will eventually fail. In this Master’s thesis, the friction drive is investigated and several improvements, such as a change of forces, dimensions and material are evaluated. The goal is to improve the friction drive to the extent that it is not worn out when the doors are opened and closed repetitively

Topics: Hertzian Contact Pressure, Rolling Friction, Finite Element Analysis, Fatigue, Material, Technology and Engineering
Publisher: Lunds universitet/Hållfasthetslära
Year: 2020
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