cad╱cam.doc

华南农业大学期末考试试卷（A卷）ONE. Completion. Fill in the blanks with English or Chinese words to make the following passage correct. (21 Scores)1. The full terms of PDM, CIMS and BOM are .2. Curves can be described mathematically by or equations.3. Synthetic curves represent a curve-fitting problem to construct a smooth curve that passes through the given data points. The typical form of these curves is a .4. Major CAD/CAM systems provide three types of synthetic curves: cubic spline, bezier curve, and curve.5. CAD/CAM systems provide designers with both and surfaces entities6. The simplest method to display surfaces is to generate a on the surface by holding one parameter constant at a time.7. CAD systems offer two approaches to creating solid models: and .8. A solid model of an object consists of both the data and data of the object.9. A B-rep model of an object consists of , , , loops, and handles. 10. To assure to produce the qualified product more efficiently, shop-floor operators must fulfill all the operation according to the file strictly. 11. Variant CAPP systems classify and code all existing parts into many families of parts on principle of .12. Most of the existing machine tools use coordinate systems.TWO. Terms Interpretation (12 Scores)1. Homogenous Coordinates2. CAPP3. FMSTHREE. True or False (18 Scores)1. CAD/CAM software utilizes a data array to save the geometry and topology of geometric models.2. A solid model is a complete, unique, and unambiguous representation of an object.3. A revolution feature is used to create axisymmetric models. It requires a cross section and an angle of revolution.4. A sweep feature is used to create a model with a constant cross section along a nonlinear axis. It is a generalization of the extrusion feature. It requires a cross section and a sweep curves.5. The fillet and chamfer features are used to change the vertex of a model.6. The shape of Bezier surface can be modified by either changing some points of its polyhedron or by keeping the polyhedron fixed and specifying multiple coincident points of some vertices.7. Analytic curve entities are points, lines, arcs and circles, fillets and chambers, and conics. Synthetic curve entities include various types of spline and Bezier curves.8. The cubic spline curve passes through the data points. Bezier and B-spline curves also pass through the given data points.9. Cones and cylinders are examples of ruled surfaces, and the plane surface is considered the simplest of all ruled surfaces.10. Disadvantages of variant CAPP are that the quality of the process plan still depends on the knowledge and background of a process planner.11. Most often, we hear terminology such as 2.5-axis, 3-axis, or 5-axis milling machines.These axes refer to the possible axes of translation that the machine tool can control simultaneously.12. Tool compensation allow a program to be written to perform milling, drilling, tapping, or boring without presetting the tool to a specific length.Four. Short Answer Questions (37 Scores)1. What is a 2.5D model? Sketch some examples. (5 Scores)2. Why NURBS curve and surface were researched? Please point out their features. (4 Scores)3. Explain how surfaces can aid in creating solid models, that is, when must you use surfaces in solid modeling? (5 Scores)4. CAD/CAM systems use parametric representation for surfaces as they do for curves. Explain how a surface is represented. (5 Scores)5. What is the difference between linear and nonlinear sweeps? (5 Scores)6. What is the input and output to CAPP? (4 Scores)7. What is the difference between NC, CNC, and DNC? (5 Scores)8. What is the benefit of using tool offset in NC programming? (4 Scores)Five. Analytic problems. Solve following problems in English or in Chinese. (12 Scores)1. Analyze how to automatically generate a NC program with CAM software, point out the process planning problems you must consider for each step. (2 Scores)2. Explain purpose of Tool Path Verification. (2 Scores)3. Read following NC