261 Каталог PRAMET 2016 Инструментальная оснастка для металлорежущих станков Стр.260

Каталог PRAMET 2016 Инструментальная оснастка Стр. 260 0261 Lab2u

EFFECTS OF IMBALANCE ON MACHINE SPINDLES, TOOLHOLDERS AND TOOLS Imbalance An imbalance produces a centrifugal force during the rotation of the spindle impeding the smooth running of the tool. This imbalance influences the working process and the life span of the spindle bearings. The centrifugal force (F) increases linearly with the imbalance (U) and squared with the number of revolutions according to the formula below. Counter balancing To compensate for unwanted centrifugal forces, the symmetrical distribution of mass must be restored with the aim of eliminating any centrifugal forces influencing the spindle bearing. Tool holders generally have compensation holes or areas which assist in directing the total amount of all centrifugal forces influencing the axis towards zero (see DIN ISO 1940). Eccentricity of center of gravity The imbalance of a spindle causes its center of gravity to deviate a certain distance from the rotating axis in direction of the imbalance. This distance is called rest-eccentricity (e) or eccentricity of center of gravity. The heavier the weight of the balance body mass (m), the greater the rest-imbalance (U) permissible. / Calculation imbalance Imbalance is a measure, specifying how much measure of distance „e" determines the distance of unsymmetrical distributed mass deviates radially from the center of gravity of an element to the rotating the rotating axis. Imbalance is measured in gmm. The axis. Imbalance is calculated as follows: U = mxr U = imbalance in gmm r = eccentricity of center of gravity in m m = mass in kg 260