第一章 制图基本知识

CHAPTER ONE    BASIC KNOWLEDGE OF HYDRAULIC ENGINEERING DRAWING

学习目标 Objects of learning

1.掌握绘图工具的正确使用方法。Master the usage of drawing tools.

2.熟记基本制图标准中的各项规定。Keep in mind regulations of drawing.

3.能按正确的绘图方法和步骤，遵循制图标准，准确的抄画各种平面图形。

Copy drawings based on drawing standards and master methods and steps.

4.掌握徒手画线的技巧。Freehand drawing

       正确使用绘图工具、了解制图标准的基本规定、掌握平面图形的画图方法和步骤是学习工程制图首先应具备的基本知识。

       One should get to know some basic regulations of drawing standards and master drawing methods and construction steps.

第一节 仪器绘图常用的工具           SECTION ONE USAGE OF DRAWING TOOLS

一、图板和丁字尺 DRAWING BOARD AND T-SQUARE

       图板用来铺放和固定图纸。图板的短边为工作边，绘图时，用胶带纸将图纸固定在图板的适当位置，如图 1-1 所示。图板要求工作边平直，板面光滑、平整、洁净。使用图板时板面和工作边不得损坏，否则将会影响绘图质量。

        The board is used to layout and fix drawing sheet. Its short edge can be used for working

edge. Drawing sheet is fixed in proper place with adhesive tape, as shown in figure 1-1. The

board is flat, smooth and clean. Drawing board surface and edges shall not be damaged, or

will affect the drawing quality.

       丁字尺与图板配合使用，主要用来画水平线。丁字尺由尺头和尺身两部分组成。使用丁字尺画水平线时，左手握尺头将尺头内侧紧靠图板左工作边，右手扶尺身，上下滑动将尺身上边对准所要画线的位置，左手按住尺身，右手持铅笔自左向右画线，如图 1-2 所示。

      With the help of T-square and drawing board, one can easily draw a horizontal line. A T-square is composed of two parts.one is its head; the other is its body. While drawing, place the head of the T-square in contact with the left edge of the drawing board with the left hand and move the T-square to the desire position, then draw lines from left to right, as shown in figure 1-2.

二、三角板 TRIANGULAR PLATE

（1）与丁字尺配合画垂直线。画线时，自下而上画铅垂线，如图 1-3 所示。

      With the help of T-square, draw vertical lines. Draw vertical lines from bottom to up, as shown in fig1-3.

（2）与丁字尺配合画 15°倍角的斜线。图线在三角板左边自下而上画线，在三角板右边自上而下画线，如图 1-4 所示。It can draw oblique lines as shown in fig1-4.

（3）两块三角板配合画任意直线的平行线或垂直线。画线时其中一块三角板起定位作用，另一块三角板沿定位边移动并画直线，如图 1-5 所示。

      Two triangular plates can be used for drawing parallel line or vertical line, as shown in figure 1-5.

三、铅笔 PENCILS

       绘图铅笔的铅芯有软硬之分，用 B 和 H 表示。B、2B…4B 数字越大表示铅芯越软且色浓黑；H、2H…4H 数字越大表示铅芯越硬且色浅淡；HB 介于 H 和 B 之间。绘图时常用 H 的铅笔画底稿和加深细线；用 HB 的铅笔写字；用 HB 或 B 的铅笔加深粗直线；将 B 或 2B 铅笔的铅芯装入圆规的铅芯插脚内，用来加深粗线的圆及圆弧，以保证与直线的颜色深浅程度一致。

      There are black and hard cores of pencil. Letter b and letter h are its symbols. B, 2B ... 4B bigger numbers show that the core of pencil is softer and the color is blacker. H, 2H ... 4H bigger numbers that show that the core of pencil is harder and the color is lighter; the type of HB is between hard and soft. Utilization of pencil and HB pencil is used to draw thick lines .H and HB pencil is drawn thin lines. 2H pencil is used to write Chinese character, letters and numbers and so on.

      削铅笔时应从无记号的一端开始，以便使用时识别。被削去的笔杆长度约 25mm左右，铅芯露出约 8～12mm 为宜，太长了容易折断，太短不宜修磨。画粗线的铅芯前端的扁平部分一般磨成 3～5mm 长。绘图铅笔的选用及削磨形状见表 1-1 所示。

     There are two kinds of pencil sharpening. The core form is used to draw manuscript and dimension. The wedge form is used for deepening and thickening lines.

      使用铅笔画线时，应保持笔杆前后方向与纸面垂直，向运动方向自然倾斜，用力均匀、匀速前进。绘图铅笔的铅芯有软硬之分，用 B 和 H 表示。According to the cone of pencil, Drawing pencils can be defined B and H.

                                                        表 1-1 铅笔和铅芯的选用与削磨形状

四、圆规 COMPASS

      圆规用于画圆和圆弧，并可以兼作分规用。圆规的一条腿有固定插脚可装钢针，钢针两端的形状不同，带台阶的一端用于画圆和圆弧时定圆心，台阶可以防止图纸上的圆心扩大，以免影响绘图的准确性。圆规的另一条腿端部能拆卸，根据需要可分别装入铅芯插脚、延长杆（画大圆用）和刚针插脚（做分规用），如图 1-6 所示。

       A compass is used to draw circles and arcs. The leg of the compass with a step pin should be facing downward and the pencil tip on the other leg should have similar height to the pin. When draw circles or arcs with different diameter or radius, adjust the pin and the pencil of the compass as necessary, as shown in fig 1-6.

五、比例尺 SCALE

       比例尺用于直接缩小（或放大）图形。比例尺只用于量取尺寸，不能用来画线。常用的比例尺有两种：一种是三棱尺，另一种是比例直尺，如图 1-8 所示。画图时直接从比例尺上量取所需的长度，可以省去繁琐的计算。

       使用比例尺的方法有两种:一种方法是将比例尺放在图纸上直接量取图线的长度；另一种方法是用分规从比例尺上量取尺寸后再移到图纸上，后一种方法适用于截取大量重复尺寸。读比例尺上刻度的方法，如图 1-9 所示。当用 1:100 的比例画图时，尺上刻度 1m实际长度是 1cm，也就是说已将实际 1m 的长度缩短为百分之一。在比例尺 1:100 的刻度上，也能读出 1:10、1:1000 等比例的尺寸。在比例尺 1:200 的刻度上，也能读出1:20、1:2000 等比例的尺寸。

        Scale is directly used to reduce (or enlarge) graphics drawing. One should know it is used for measuring the size and cannot be used to draw lines. Each kind of scale is calculated in proportion to the length. Users can get the size from the desired length conveniently and don't need to calculate.

六、曲线板 CURVE DRAWING TEMPLATE

       曲线板用于加深非圆曲线。用曲线板画曲线时，应先徒手轻轻地将各点用细线连成光滑的曲线，然后在曲线板上选择与曲线吻合的部分，尽量多吻合一些，一般应不少于四点，从起点到终点按顺序分段加深。加深时应将吻合段的未尾留下一段暂不加深，待下一段加深时重合，以使曲线连接光滑，如图 1-10 所示。

       A Curve drawing template is for drawing non circular curves. First of all, connect all the points with pencil slightly, then select the curve part coincident to the line and deepen the line along the curve plate. Be sure to make the line smooth during deepening the curve line.

七、擦图片和模板 ERASING TEMPLATEAND DRAWING TEMPLATE

      擦图片用于加深时擦除错误的图线。使用擦图片时，应将要擦去的图线从擦图片的孔中露出来，然后用橡皮擦去，这样可避免擦掉其它部分的图线。

      It is used to erase error lines during deepening drawings. One should make the wrong line expose from the drawing then wipe it out. With the help of the error plate, one can correct lines easily.

      模板用于画各种常用符号和标准图例。使用模板时，应将模板上相应的符号或图例放到图纸上需要绘制处，用笔在符号或图例内画一周即可。如尺寸箭头、立面高程符号等。

      Drawing template can be used to draw all kinds of labels and cut lines of standard. Put the related symbols in the location of the drawing and copy them. In this way, one can get arrows of dimensions and elevation symbol so on.