四杆机构 螺纹试题（Four bar mechanism thread examination questions）.doc

四杆机构 螺纹试题（Four bar mechanism thread examination questions） Fill in the blanks (1 cents per hour, 30 points altogether) 1. machines have three characteristics. They are man-made combinations of objects; they have definite relative movements between them; they are used to substitute or reduce human labor to accomplish useful mechanical work. 2. the kinematic pair in planar mechanism is divided into high pair and low pair. 3. when the original number is equal to the number of degrees of freedom mechanism, mechanism has determined relative motion. The calculation formula of DOF of 4. planar mechanism is F=3n-2Pl-PH. 5. cam mechanism consists of three parts: cam, follower frame. 6. threaded connections have four basic types, namely, bolt connection, stud connection, screw connection and fastening screw connection. There are two conditions for the existence of 7. cranks: (1) the sum of the length of the longest rod and the shortest rod is less than or equal to the sum of the remaining two rod lengths; (2) the shortest rod or its adjacent rod shall be a frame. 8. the calculation of freedom should pay attention to such problems as compound hinge, partial freedom and virtual restraint. The basic types of 9. hinged four bar mechanisms are crank rocker mechanism, double crank mechanism and double rocker mechanism. 10. the most common intermittent motion mechanisms are ratchet mechanism, Geneva mechanism, incomplete gear mechanism and cam type intermittent motion mechanism. 11. according to the number of spiral lines, the thread can be divided into single thread and single thread Two. Select (2 points per game, 20 points) 1. the internal combustion engine belongs to the machine (a). A. power part, B. work part, C. drive part, D. control part 2. the kinematic pairs between the wheel and the rail belong to (C). A. revolute pair, B. moving pair, C. plane pair, D. pair, spatial motion pair 3. institutions, in order to ensure that the organization can work normally, must specify th