Research Of Dynamic Unbalance Detection And Adjustment Method In HDDs

Dynamic balance is the key process in the assembly of Hard Disk Drives, and the unbalance value will affect the performance of HDDs such as vibration, thermal, read & write of head, etc.. So the unbalance measurement of HDDs is the key process in HDDs assembly. The unbalance values of disk, base motor and couple value of disk & base motor are got by the unbalance measurement system. In the HDDs assembly, there is a little shift after disk mounting on spindle, so the technologies of unbalance measurement and adjustment of disk and motor systems are very improtant. The research work of unbalance measurement and adjustment will improve the stability, reduce the vibration in HDDs running and the performances of HDDs.In the thesis a measurement system is built based on the influencing coefficient method. Research work is carried out including the mechanism design of unbalance measurement, the method of signal acquisition and process, the process of mathematic model measurement for HDDs unbalance measurement. Then the function of unbalance measurement system is obtained by the least square method and influencing coefficient method with the software of MINITAB. For unbalance adjustment of HDDs, the disk position is adjusted with additional hitting by PZT to reduce the unbalance value.For experimental verification of the unbalance measurement system, accuracy and precision of system are calibrated by using the 6σ method. The function of measurement system between values of vibration signal and unbalance value are built by analysis of the experimental data. The system accuracy is calibrated by the bisa of test results and the precision is calibrated by the Gauge R&R of test result. Unbalance adjustment pass ratio and efficiency of HDDs are evaluated by comparison of two different control methods. The hitting angle and disk holding force of unbalance adjustment system are adjusted in advance.