Hello, students. We now learn the basics of mechanical mapping: size note, basic scale. This is a part of our follow-up study. Sizes are indicated in the figure. The drawings are used in the actual production, and the graphics on the drawings represent the shape of the parts and the size of the parts. The complete drawing must have dimensions. Size is the main basis for manufacturing parts. When size labels are wrong, incomplete or unreasonable, they can cause difficulties in processing, testing, assembly, etc., and even economic damage to waste products. Therefore, in mechanical mapping studies, attention must be paid to size labels, which are consistent with national standards and comply with national standards. See size note method (gb/t4458. 4 - 2003). Part i. Basic requirements for marking size 1, correct: the relevant provisions of national standards are to be met. Complete: to mark all the dimensions required for the manufacture of the spare parts, without omission or repetition. 3. Clarity: the size of the configuration should be clear, clear and readable. Reasonable: the dimensions indicated shall meet the design and process requirements. Part ii. The true size of the underlying machine, the size of which is indicated, should be based on the size values indicated on the drawing, and is not related to the size of the graphic and the accuracy of the drawing. Where the dimensions in the pattern are in mm, the code or name of the unit of measure shall not be required; if other units are used, the corresponding unit of measure shall be indicated by the code or name. The dimensions indicated in the pattern are those of the final completion of the equipment shown in the sample, otherwise described. Each size of the package shall normally be indicated only once and on the most clear graphics reflecting the structure. (c) seek to simplify the labels, while ensuring that they do not give rise to misunderstandings and do not give rise to an understanding of multidimensionality. The size configuration is reasonable. Part iii. A full dimension of the dimensions indicated includes size limits, size lines, size line terminals and size numbers. 1 the dimensions limit is the line indicating the dimensions. The size limits are: a, drawn with fine lines; b, derived from the contours, axes or symmetry of the graphics, which can also be used directly as size lines; c, size lines should generally be vertically linked to size lines; d, when marking in smooth transitions, the contours must be extended with fine lines and the size limits must be drawn from their nodal points; e, size limits should be in excess of around 2-5 mm. 2. Size line a, which shall be drawn with a fine line; b, which shall not be drawn on an extended line of other drawing lines; c, linear dimensions, which shall be parallel to the specified size segment; and d, size lines, and size lines, or between dimensions and dimensions, which shall be avoided as far as possible. Please learn more about size lines. 3. Size-based terminals are important components of size. What are size terminals? There are generally three structural forms: arrows, 45° line and dots. Of these: arrows apply to all types of engineering drawings; 45° fine slash applies to building drawings, where the size line and the size line must be vertically linked; and dots are often used as size terminals in mechanical size mappings that mark small areas of narrowness. 4. Numbers of sizes are an important component of sizes and are written in standard fonts, and in the same image the height of words should be consistent. No drawings can pass through size numbers. A. Linear size figures are usually stated above or at the break of the size line; b. Angle dimensions are written horizontally; c. Size numbers are not allowed to be passed by any drawing line, otherwise the drawing is to be severed or indicated; in this chart, the centre line is disconnected. D. The note direction for linear size numbers is as follows: the size of a horizontal direction is up, the size of a vertical direction is up, the size of a vertical direction is up, the size of a vertical direction is up, the size of a tilt is above; the size of a 30° range is avoided; the fourth part, the common size note is 1 and the angle size line is to be drawn into a circle arc, the centre of which is the top of the angle. The dimension boundary follows the path. Angle numbers are written horizontally. 2. When arc long size 3 and diameter sizes are indicated in diameter sizes, a symbol shall be added to the size numbers. When marking the diameter size of a circle or a circle larger than half a circle, the dimensions are defined by the circle, with the size line passing through the centre of the circle, and a diameter symbol is added to the size number. The diameter size of the arc should be drawn to slightly more than the centre of the circle, with only arrows pointing to the arc at the end of the arc. When indicating the diameter of the face of the ball, the symbol s4 and the radius dimensions shall be indicated in front of the symbol, the symbol r shall be marked in front of the dimensions less than or equal to half a circle, the size line shall be drawn from the centre to the arc with only one arrow, and the symbol r's large arc radius shall be marked in front of the dimensions when the radius is too large, or if it is not possible to mark its centre position within the drawing area, it may be indicated in the manner indicated in the left chart, but the size line may only be rotated once at the most; if it is not necessary to mark its centre position, it may be indicated in the manner indicated in the right chart. It should be indicated in the view of the arc. When indicating the face radius, the symbol s should be preceded by the symbol r. 5. The small size of the narrow part does not have sufficient position to draw arrows between the dimensions, and the length of the dots instead of the arrow is the same as the width of the tail of the arrow. 6 the symmetrical representation method, part v, simplifys the size of the scalding tank by the size representation method of the square of the hole in the cone: the square is a square symbol and is attached to the long side size number. Part vi, the symbols and abbreviations commonly used for markings, are expected to be remembered and read and written. Job: identification error. It is hoped that the students will carefully compare the two maps and that, based on the knowledge gained during this course, they will indeed be able to master the method of mapping the sizes of the machines。
