99级MMT重考考卷.doc

1. Questions: (1) What are the differences between the pitch circle and the reference circle? What are the differences between the working pressure angle (’ and the pressure angle (?(4%) (2) What are the advantages and disadvantages of helical gears?(4%) (3) Why is the mid-diameter of a worm defined as a standard value?(3%) (4) What measures must be taken to prevent a Geneva wheel from free rotating during dwell time?(3%) (5) What are the functions of a flywheel? Where should the flywheel be mounted?(4%) 2. Locate all instant centres of the linkage for the position shown. (4%) 3. Draw the kinematic diagrams of the mechanism using a suitable scale.(4%) 4. In the cam-linkage shown below, the driving crank AB rotates together with the cam about the shaft A. By designing the cam profile correctly, the revolute centre C can move along a predetermined locus. Analyze the motion transmission route and draw its structural block diagram. What is the combination pattern of the combined mechanism?(6%) 5. Calculate the degree of freedom of the mechanism shown. In this mechanism, ABCD EF. Indicate compound hinge, passive DOF, redundant constraint before the calculation of the DOF.(6%) 6. The first line of the subroutine RRP, RPR, and LINK is: SUB RRP(M,YB,LAB,XA,YA,VAX,VAY,AAX,AAY,QAB,WAB,EAB) SUB RPR(XA, YA, VAX, VAY, AAX, AAY, XC, YC, VCX, VCY, ACX, ACY, Q, W, E) SUB LINK(XA,YA,VAX,VAY,AAX,AAY,Q,W,E,LAB,XB,YB,VBX,VBY,ABX,ABY), respectively. In the quick-return mechanism shown below, XA=XB=0, YA=YF=-4, YB=6, LBC=19mm, LDA=9.5mm, LDF=29mm. The crank BC rotates at a constant speed of 10 rad/sec. A main program is required to analyze the output motions of the point F. The mechanism will be analyzed for the whole cycle when the driver BC rotates from 0( to 360( with a step size of 5(.(12%) 7(1). In an offset slider-crank mechanism ABC, the crank AB is a driver. The length of the crank LAB=25mm. The offset e=10mm. The maximum pressure angle (MAX=30(. Design the offset slider-cra