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robotics Designing the Mechanisms for Automated Machinery Part 3

Tham khảo tài liệu 'robotics designing the mechanisms for automated machinery part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 2.4 The Kinematic Layout 55 run in series one after the other this is the usual way to think about a manufacturing process . Figure 2.16b illustrates the simultaneous running of the operations to economize the production time. The example shown in Figure 2.10 conforms to this approach. Exercises Show the timing diagrams for the following automatic processes 1. Four-stroke internal combustion engine. Use the circular approach. 2. Washing machine any washing regime . Use the diagram given in Figure 2.15. 3. Sewing machine. Use the linear approach. 4. Spring-producing machine Figure 2.4 for the spring shown in Figure 2.3c . 5. Automatic record player. 2.4 The Kinematic Layout After the processing layout and timing diagram are finished comes the turn of the kinematic layout. At this stage the designer has to choose the means by which to effect the required movements of tools as defined in the processing layout. A variety of mechanical concepts are at the designer s disposal for this purpose. These may be known and established concepts on the other hand sometimes new concepts must be found. Any mechanism chosen for carrying out a specific movement needs a drive. We will now consider and compare those most commonly used beginning with mechanical drives. See Table 2.1. TABLE 2.1 Mechanical Systems Advantages 1. Relative clarity of the mechanical layout compared with an electric circuit for instance . 2. Absence of the need for a specific power supply. 3. Possibility of implementing different kinds of movement or different displacement laws. 4. Relative ease of achieving accurate displacements. 5. Rigidity of the mechanical links. 6. High accuracy of ratios in movement transmission. Disadvantages 1. For spatially extended constructions cumbersomeness of the kinematic solution. 2. Difficulties in creating relatively rapid movements. 3. Difficulties in generating very large forces. 4. The necessity for special protective devices to avoid breakage of expensive links. TEAM LRN