Study of the dependence of the natural frequencies of a rotor system with a vertically positioned rotor on the preload

Abstract

The article discusses the possibility of using a method for determining the preload force for trust and radial bearings of spindle assemblies for high-speed milling. Previously, a method was developed and tested for determining the preload force of bearing supports on high-speed grinding electrospindles with a horizontal spindle.
 The object of study is a support with angular contact bearings 7004 ACD_P4A SKF and a vertical rotor. An information-measuring system has been developed, which consists of PCB 352C34 vibration acceleration sensors, a Vishay 614 force sensor, an NI-cRIO-9056 controller, NI 9250, NI 9237 and NI 9481 modules, and software written in the National Instruments Labview language.
 The system of test actions has been improved due to its automation. Test effects began to be carried out using a solenoid with a core, which was controlled by an NI controller and developed software. Due to this, the same time delay was formed between the test action and the start of recording the vibration acceleration signal.
 Vibration acceleration signals are obtained for the entire preload range. To study the controllability of the unit, two vibration acceleration sensors were used: with a parallel and perpendicular arrangement of the axes of the direction of vibration and test action. For the first and second groups of vibration accelerations, spectral transformations were carried out, and the amplitude-frequency characteristics of the assembly were obtained for the entire range of preload values.
 As a result of the work, it was concluded that the presented methodology and criteria are applicable to high-speed milling spindle assemblies with a vertical rotor. It is also shown that this technique can be automated.