机械制图（Mechanical drawing）.doc

机械制图（Mechanical drawing） With the origin of map like chronicle very early, such as China song Su Song Written by Zhao Gonglian and the astronomical timekeeping instrument has a new instrument to image method in the pattern, the Ming Dynasty Song Yingxing book Heavenly Creations is also a large number of mechanical drawing, but it is not rigorous. In 1799, the French scholar Mongolia published the descriptive geometry works, since in the mechanical drawing graphics began in strict accordance with the drawing projection theory of descriptive geometry. Standard. To make people on the patterns involved in the format, text, graph, line graph simplification and symbolic meaning of common understanding, and gradually develop a unified specification, and developed into mechanical drawing standards. Many countries have their own national standards, international organization for standardization to develop international standards. Chinese national mechanical drawing standards formulated in 1959, in 1974 and 1984 after the revised two times. The provisions in the standard of mechanical drawing of the project are: drawings and format, proportion, font and line chart. In the drawings and format specified in the corresponding frame size drawing standard format size and the drawings. Refers to the proportion of the size and length of drawing parts of the actual size ratio, except as permitted in the proportion of 1:1 drawings, Only allow provisions in the standards used for scale and scale drawing. In China, provisions must be written according to the long long Chinese characters words, letters and numbers according to the provisions of the writing structure. Line provisions are nine kinds of specifications, such as for drawing visible contour thick solid line, dotted line, not for rendering visible contour line for fine lines, draw the axis and the center line of symmetry for drawing lines and section lines of thin lines etc.. Mechanical drawings are the main parts drawing and as