Mechanical drawing for the size of the drawing A0-A4 size are clearly defined, A0 size of 1189mm × 841mm, A1 size of 841mm × 594mm, A2 size of 594mm × 420mm, A3 size of 420mm × 297mm, A4 size of 297mm × 210mm. 210mm.
A. Common Drawing Tools
1. drawing board drawing board is used to fix the rectangular wooden board of the drawing. Requirements:
1) flat, smooth surface;
2) the left side of the "guide" should be straight.
Commonly used board specifications:
0 (900mm × 1200mm), 1 (600mm × 900mm), 2 (450mm × 600mm)
2. T-rule T-rule by the "ruler" and "ruler body
The ruler consists of "head" and "body".
Use:
1) With the drawing board to draw parallel lines.
2) Work with the graph board and triangle board to draw angle lines and vertical lines.
3. Trigonometry A pair of trigonometry boards consists of two trigonometry boards, one 45° and the other 30° (or 60°).
Use:
1) with the butyl ruler to draw perpendicular lines, inclined lines (15o multiples of the angle of the angle line): 45 °, 30 °, 60 °, 75 °, 105 ° and 150 °, etc.;
2) two pieces of triangular board with the parallel or perpendicular line to draw a known line.
4. scale scale commonly known as the "three-pronged ruler", *** there are six commonly used proportional scale, is used to draw different sizes of proportions of the figure.
Note: the scale can not be used as a ruler to draw lines, can only be used to measure the size of different proportions.
5. Curve Board Curve Board is used to draw irregular non-circular curves of the tool (can be used in both positive and negative).
How to use:
1) ensure that at least 4 points (or more than 4 points) and the edge of the curve board coincide with the connection of these 4 points (or more than 4 points);
2) there should be a repetition of the two segments.
Two, commonly used drawing supplies
1. Pencil pencils are divided into: hard, medium and soft three.
Labeling: 6H, 5H, 4H, 3H, 2H, H, HB, B, 2B, 3B, 4B, 5B, 6B **** 13 kinds. Among them: 6H is the hardest, HB is medium hardness, and 6B is the softest.
Selection and use of pencils:
1) When drawing underpainting, H or 2H pencils should be used and sharpened to a sharp conical shape;
2) When drawing shapes, B or HB pencils should be used and sharpened to a quadrangular shape (flat spade shape);
3) Pencils should be used from the end that is not labeled in order to preserve the pencil's softness and hardness markings.
2. Drawing PaperDrawing paper has a front and back side, when drawing, you should choose to use the front side of the drawing.
Recognition method: use an eraser to wipe a few times, it is not easy to hairy side is the front, or using the observation method, the brighter side of the reflection is the front.
Three, commonly used drawing instruments
1. Gauge is used to intercept the size of the gauge, equidistant line segments or circumference of the tool.
How to use: the two needle tips should be aligned when they are together.
2. Circle gauge is used to draw "circle" or "arc" tool.
1) its accessories are: steel pin pins, lead core pins, duckbill pins, extension rods.
2) Its use: the steel pin end of the circular gauge should be the end of the "shoulder"; when drawing a large circle, the shoulder should be kept parallel to the core of the lead, aligned.
In addition to the above drawing tools and supplies, there should be: ruler, protractor, eraser, eraser picture, knife, sandpaper, tape paper and so on.
Four, drawing format and format (GB/T14689-1993)
1. Drawing format in order to ensure that the size of the drawings of the unity of the drawings, in order to facilitate the binding of the drawings, drawings, drawings, drawings, indentation, drawings of the format of the provisions of:
Drawings Format and format (GB/T14689 - 1993)
Drawing size and code: A0, A1, A2, A3, A4, A5
2. Frame format (frame line) drawings in the drawing before the drawing of the frame line must be drawn with a thick solid line, the drawing (graphics) should be within the frame line.
There are two types of frame line format:
(1) do not leave the binding edge format (2) leave the binding edge format.
3. title bar and orientation of the title bar in the direction of the text for the direction of view. Title bar format, content and size in the national standard (GB / T10609.1-1989) has been stipulated, the student mapping work is recommended to use the title bar format shown in the figure.
4. Additional symbols
1) centering symbols: in order to copy or photograph the positioning of the convenience of each side of the midpoint of the centering symbols are drawn.
Starting from the drawing boundary into the frame about 5mm, line width of not less than 0.5mm thick solid line. When centering symbols in the title bar range, then into the title bar part of the omission not to draw.
2) Direction Symbol: When the drawing and reading direction is perpendicular to the direction of the title bar, in order to clarify the direction of the drawing and reading, a direction symbol (equilateral triangle with thin solid lines) is drawn at the centering symbol.
V. Proportion
1. Terminology
(1) Proportion: the ratio of the graphic in the drawing to the linear size of the corresponding elements of the physical object.
Original ratio: the ratio of the ratio of 1, that is, 1:1.
Enlargement ratio: the ratio of the ratio of more than 1, such as 2:1.
Reduction ratio: the ratio of the ratio of less than 1, such as 1:2.
2. Proportion of the series
(1) Preferred in the preferred choice of the series of proportions in Table 1-2, and then choose to allow selection of the proportion of the series.
(2) regardless of the ratio, the size of the labeled values should be the actual size of the physical dimensions. Such as
In order to see the convenience of drawing the drawing. Should be drawn as far as possible in proportion to the original value of the machine parts. If the machine parts are too large or too small, should be drawn using the preferred ratio specified in table 1-2.
Whether the drawing is enlarged or reduced drawing, labeling size, should be according to the actual size of the machine size labeling, and the proportion of the drawing has nothing to do.
3. Proportional labeling
1) labeled in the title bar.
2) labeled below or to the right of the view name. Such as I / 2: 1, B-B / 5: 1, etc..
Six, font (GB/T14691-1993)
Drawing in addition to the expression of the graphics of the machine, but also with the text and figures to explain the size of the machine, technical requirements and other content. In the drawings written font must be: neat font, clear strokes, evenly spaced, neatly arranged.
The number of the font, known as the font height, expressed in h. Its nominal size series: 1.8, 2.5, 3.5, 5, 7, 10, 14, 20mm. such as writing a larger word, the height of the font should be in accordance with the rate of increase.
1. Chinese characters in long imitation Song font
2. Letters and numbers Letters and numbers can be written in italic or straight. Italicized characters are written with the head of the character tilted to the right at 75 degrees from the horizontal datum line.
ABCDEFGHIJKLMNOPQRSTUVWXY Latin Alphabet Example
bcdefghijklmnopqrstuvwxy
ⅠⅡⅢⅣⅤⅥⅦⅧIXIXX Roman Numerals Example
0123456789 Arabic Numerals Example
ABCDEFGHIJKLMNOPQRSTUVWXY
Examples of Greek Letters:
1) Type A and Type B:
Type A font: stroke width = h/14 (h is the height of the character)
Type B font: stroke width = h/10 (h is the height of the character)
2) Straight and italicized (tilted to the right at a 75o angle). ) two kinds.
seven, the line (GB/T17450-1998)
The line is used to draw a variety of types of lines.
1. The form and application of graphic lines (as shown in Table 1-4)
2. The size of the graphic lines graphic lines are divided into thick, thin two kinds. The width of the thick line as a basis, the width of the thin line should be half the width of the thick line. In the various graphic lines listed in Table 1-4, in addition to the thick solid line, the width of various other graphic lines should be half the width of the thick solid line. Figure line width of the recommended series: 0.18, 0.25, 0.35, 0.5, 0.7, 1, 1.4, 2? mm, the width of the thick line is generally in accordance with the size and complexity of the drawing in the 0.5 ~ 2? mm between the choice.
3. Drawing of lines
(1) the same drawing, the width of similar lines should be the same, the length of the line segments and intervals should be approximately equal.
(2) a variety of drawing lines intersect, should be intersected by line segments, and should not be intersected by points or gaps.
(3) Dashed lines should intersect solid lines with gaps. An arc of a dashed line is tangent to an arc of a solid line, and a gap should be left.
(4) the "point" of the dot-drawing line, is a small line segment, not a point. The beginning end of the point drawing line is a straight line segment, and should be beyond the contour line 2 to 5mm.
(5) Drawing the center line of the circle, the center of the circle should be the intersection of the line segments. The ends of the dotted line should be beyond the circle 2~5mm. the center line of a small circle can be used as a thin solid line instead of a dotted line.
(6) When a solid line overlaps a dotted or dashed line, draw a solid line; when a dashed line overlaps a dotted line, draw a dotted line.
(7) Diagram lines shall not overlap or be confused with text, numbers or symbols. When it is unavoidable, the text, figures or symbols should first be ensured to be clear. When some graph lines overlap each other, should be in accordance with the order of thick solid lines, dotted lines, dotted lines, only the first one.