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Development of high accuracy classification system for small particles

小颗粒高精度分级系统开发

基本信息

批准号：
14550736
负责人：
MATSUSAKA Shuji
金额：
$ 2.56万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

High accuracy size classification is required to improve the performance of functional particles such as solder balls. In this work, a size classifier with twin rollers has been developed to realize high accuracy size classification of spherical particles. Since the two rollers are arranged at a certain inclination with a small opening angle, particles move along the gap between the rollers, and fall down at a point where the width of the gap exceeds the diameter of the particles. To clarify the dynamic behavior of the moving particles along the gap, microscopic observation was carried out, and images recorded with a high-speed digital camera (1/8000 fps) were analyzed. The particle velocity is proportional both to the angular velocity of the rollers and to the tangent of the inclination angle. The particles are not only rolling but also jumping slightly but continuously. The small jumps are caused by the friction between the particle and the rollers, and the forward movement of particles is due to the axial component of the gravitation. The particle velocity can be formulated with the circumferential velocity of the rollers, inclination angle, and friction coefficient. In addition, the particle movement depends on the operational conditions, i.e. directions and rotational velocities of the rollers, but not on the diameter of the particles if they are several hundred micrometers. For smaller particles, the adhesion between a particle and the roller affects the particle movement. The small surface roughness of the rollers lowers the adhesion and 98% of particles were able to be classified even though the particle diameter is 100 μm, and the accuracy of the size classification was within 1 μm.

为了提高焊锡球等功能性粒子的性能，需要高精度的尺寸分级。为了实现球形颗粒的高精度分级，研制了一种双辊分级机。由于两个辊以一定的倾斜度以小的开度角布置，因此颗粒沿着辊之间的差距移动，并且在差距的宽度超过颗粒直径的点处落下。为了明确沿着差距移动的颗粒的动态行为，进行显微镜观察，并分析用高速数码相机（1/8000 fps）记录的图像。颗粒速度与辊的角速度和倾斜角的正切都成比例。粒子不仅在滚动，而且还在轻微但连续地跳跃。小的跳跃是由颗粒和辊子之间的摩擦引起的，颗粒的向前运动是由于重力的轴向分量。颗粒速度可以用辊的圆周速度、倾角和摩擦系数来表示。此外，颗粒的运动取决于操作条件，即辊的方向和旋转速度，但如果颗粒为几百微米，则不取决于颗粒的直径。对于较小的颗粒，颗粒与辊之间的粘附影响颗粒的运动。小的表面粗糙度降低了粘附力，即使粒径为100 μm的颗粒也能够被分级98%，并且尺寸分级的精度在1 μm以内。