【作者】 姚华平；

【导师】 黄平；

【作者基本信息】 华南理工大学 ， 机械设计及理论， 2009， 博士

【摘要】 随着日益增加的大量信息及数据的需要和科学技术的飞速发展,计算机硬盘不断地在更新换代,硬盘技术的发展一方面希望通过减小头盘间隙以提高磁盘记录密度,另一方面又要求磁头在整个磁盘工作区域内保持稳定的头盘间隙,以获得稳定的信号电压和较强的抗干扰能力。磁头在盘面上的飞浮特性,成为影响硬盘存储性能的重要因素。本文以带时间项的FK-Boltzmann修正模型的广义雷诺方程和三个自由度的动力学方程联立的动态控制方程为理论基础,用时域分析法和频域分析法分析了磁头的动态特性。最后,本文还进行了实际硬盘的动态实验研究。首先,对超薄气膜动态润滑控制方程求解方法进行了分析,本文在原有数值求解过程中采用的迎风格式以剪切流项为迭代主项解决大轴承数计算失稳问题的基础上加入迎风格式对时间项处理,较好地解决了动态润滑方程计算稳定性问题。并沿用在整个润滑区域引入调和流量因子改变大阶梯下流量变化,以减小计算偏差。通过将一维近似解析解、平均算法和本算法的计算结果进行对比表明:本算法与近似解析解更接近,并用本方法对现在正在使用的几种不对称磁头进行计算,每种都得到很好的收敛性,进一步说明了本方法的收敛性和准确性。然后,将动态润滑方程和动力学方程联立组成了超薄气膜动态特性控制方程组。通过采用有限差分法联立求解控制方程组对超薄气膜的动态时域特性和频域特性进行了分析,并编制了具有自主版权的分析软件。在时域分析中,通过求解方程得到在受到不同外界激励下,磁头的飞行姿态和气膜润滑性能随时间的变化规律。结果显示在受到外界微小扰动后,磁头会在一定时间内恢复到初始平衡状态。磁头在受到上下方向振动和俯仰方向的波动时,磁头的动态润滑特性影响比较大。另外对磁头的越障能力进行了分析,结果表明磁头能够顺利地飞越微小障碍物,之后以一定频率做衰减运动,最后回到初始平衡状态。在频域分析中,采用摄动法对气膜的刚度系数和阻尼系数进行了分析计算,得出了气膜刚度系数和阻尼系数随频率的变化的规律。气膜上下方向的厚度和俯仰方向的角度对气膜刚度的影响比较大,而侧翻角和磁盘转速对其也有一定的影响。最后,对磁头的动态润滑特性进行了实验研究。通过将激振器与实验硬盘连接,搭建了硬盘振动实验装置。利用硬盘生产厂家的动态飞高测试仪和动态电性能测试机测试了不同转速下磁头的飞高和电压信号输出值,从而获得电压差值与磁头飞高振动幅度的关系曲线图。然后,对生产厂家生产的同型号硬盘进行了不同频率振动下的测试。通过引线获取了硬盘磁信号的输出值,并通过分析讨论了振动频率对信号输出的影响。用前面电压差值和磁头飞高振动幅度的关系曲线,定量判断了磁头飞高的振动幅度。最后,对冲击实验结果和理论计算结果进行了分析比较,得出了两种结果趋势一致的结论。更多还原

【Abstract】 With the development of computer technology and increase of the need for large amounts of information and data, hard drives are being upgraded continually. There are two important aspects to consider during the development process of the hard disk driver. One is that the reduction of clearance between head and disk can increase the recording density, and the other is that in order to obtain stable signal voltages and better capacities of resisting disturbance the clearance between the head and disk must keep stable. Flight characteristics of head become important factors that can affect memory property of the hard disk driver. This dissertation analyzes dynamic characteristics of the head by using time domain analysis and frequency domain analysis based on the time dependent FK-Boltzmann modified Reynolds equation and the three degree freedom dynamic equations.Firstly, the method of solving ultra-thin lubricating control equation was analyzed. In this dissertation, upwind scheme was adopted. The destabilization in calculating caused by a large bearing number was overcome by taking shear flow and time item as the principal iterative terms. Moreover, the harmonic flow factor was imported in the whole lubricating region to alter the variation of flow rate at the big steps in order to diminish calculated deviation. Compared the results of present scheme with the results of mean algorithm and one dimensional approximate analytic solution, it was showed that the results of the present scheme is more approximate to the analytic solution. Then this method was used to calculate the pressure distribution of several dissymmetry disk heads. All calculations have good convergence. The results confirmed the convergence and the accuracy of this scheme.Then the simultaneous control equations were built up. The dynamic characteristics of the ultra-thin gas film in time domain and frequency domain were analyzed by using finite difference method to solve the control equations. Based on the work, analysis software with the autonomous copyright was produced. In the time domain analysis, the rules for variation of flying pose of the magnetic head and lubricant performance of the gas-film with time was obtained through solving the equations. The results show that the magnetic head can recover to equilibrium in a certain time after undergoing a slight disturbance from outside and that the vibration in the height direction and fluctuation in the pitch direction have strong impact on dynamic lubricant property of the head. In addition, the obstacle-passing capacity of the head was analyzed. The results indicate that the head can surpass small obstacles successfully and then get back to equilibrium after a period of decaying oscillation at a certain frequency.In the frequency domain analysis, the calculated analysis on the stiffness coefficient and damping coefficient of the gas-film was conducted using perturbation method. Rules for variation of the stiffness coefficient and damping coefficient with frequency were gained. The rules show that the gas-film stiffness relies heavily upon the gas-film thickness along the height direction and the angle in pitch direction, and it is somewhat dependent on the rolling angle and the rotation velocity of the headAt last, the dynamic experiments on real hard disks were carried out in the present dissertation. A vibration experiment table for the hard disk was set up by connecting the hard drive with a vibration exciter. The values of the flight height and the output voltage of signal on different rotate speeds were tested by using the dynamic flying height tester and dynamic electric tester provided by the disk manufactory. The relational curves between output voltage differences and vibration amplitudes of heads were gained. Then hard disks of same type were tested under different vibrating frequencies. Magnetic signals were acquired via the lead wires. The influence of vibrating frequency on signal was discussed in addition. Fluctuation ranges were quantitatively judged by utilizing the flight height curve varying with voltage. After comparing the results of impact experiment and simple harmonic vibration experiment with the theoretical results respectively, we may safely draw the conclusion that the experimental results are consistent with the theoretical results.更多还原