Expandable bolt HEICO-TEC®

Coupling bolt connections of gears and shafts, as used in wind turbines, turbines of hydroelectric power plants, gas turbines or in drive technology in general, pose a major challenge for technicians and engineers already in the planning phase. Conventional fitted bolts are traditionally used in order to transmit the greatest possible transverse forces through positive locking. This contradicts the interpretation of the connection, which assumes a clearance-free form-fit. To achieve a clearance-free form-fit, time-consuming and costly additional measures are often required, such as freezing in order to press-fit bolts. Even with careful preparation, it often turns out during assembly that the fitted bolts and bores do not match because the required manufacturing tolerances cannot be achieved. The bores then have to be laboriously reworked on-site. Despite all efforts to achieve a perfect form-fit, clearance reappears in the connection during pre-tensioning, as the fitted bolts contract radially due to transverse contraction. Typically, this is not apparent to the user and leads to micro-movements in the joint under high loads. Even minimal shifting causes the fitted bolts to tilt in the bore. As a result, the coupling flanges are subjected to extreme localized stresses, which can lead to plastic deformations. These increase the clearance in the connection which leads to greater movements in the joint and further increases the clearance - a vicious cycle.