Example 4: Application to the Watch Bearing
In Chap. 10, we have briefly described the design of a surface tension based gripper to be used in the placement of 0.3- or 0.5-mm diameter balls of a watch ball bearing. Chapter 19 has described the characterization of this gripper and the contact angles made by liquids that could be used (isopropanaol, water, and oil). This chapter aims at detailing the results of the typical micromanipulation task, illustrated in Figs. 20.1 and 20.2. The 0.5-mm diameter ball “floats” by surface tension on a spherical cap-shaped water drop posed on a steel substrate (Fig. 20.1a), the gripper (ripper D, see Table 19.1 for details) is aligned above the ball (Fig. 20.1b) and then moved downwards until contact with the ball. The result of the pick operation can be seen in Fig. 20.1c. Then the gripper is moved toward the ball bearing (Fig. 20.1d) and positioned above the cavity in which the ball is to be placed (Fig. 20.2a). The ball is positioned in its final location (Fig. 20.2b) and the release takes place by moving the gripper radially outwards (Fig. 20.2c and d).
KeywordsContact Angle Capillary Force Ball Bearing Internal Channel Placement Error
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