Chapter 9 End Effectors ff ff 275 Copyright Goodheart-Willcox Co., Inc. SCHUNK Intec Inc. Figure 9-5. This two-fi internal gripper is hydraulically operated with parallel motion and finger is designed to grasp heavy loads. PHD, Inc. Figure 9-6. A rotary joint gives this gripper one additional degree of freedom. To handle objects with different shapes, fi ngers can be fi interchanged. For grasping cylindrical objects, V-shaped fingers are recommended, fi Figure 9-7. The V shape has 7 7 two points of contact on each fi nger, ensuring that the fi object is centered. Self-aligning, padded fi ngers are used fi to grip fl at objects. Fingers may also have cavities of more fl than one size or shape. Multi-cavity fi ngers may be neces- fi sary if an object changes shape or size during processing. Three-Finger Grippers. Three-fi grippers sim- finger ulate the action of the human thumb, index fi nger, and fi third fi nger, fi Figure 9-8. This confi is better than figuration that of two-fi grippers for grasping curved, spheri- finger cal, or cylindrical workpieces. Four-Finger Grippers. Four-fi grippers can finger grasp square and rectangular parts. The four fi ngers fi close simultaneously to permit easier part orientation. Four-fi grippers are often constructed from a pair of finger two-fi grippers. finger Collet Grippers Collet grippers are end effectors used to pick and place cylindrical parts that are uniform in size. Unlike fi nger fi grippers, collet grippers deliver 360° of clamping contact. They have a strong clamping force that allows rapid part