泵叶轮和泵体的测绘

泵损坏后，当购买不到这台泵的备件时，只能实地测绘来解决。泵的测绘主要是泵叶轮和泵体的测绘，因为泵的叶轮和泵体决定了泵的性能，同时泵的叶轮和泵体测绘绘图比较困难。它不但形状是一个曲面，图纸表示方法也很特殊，所以这里主要介绍泵叶轮和泵体的流道水力模型的测绘、绘型方法，而其他零件的测绘绘图同一般机械零件的测绘制图，不作详细介绍。

泵叶轮和泵体的测绘方法很多，下面介绍的方法是我们从实践中总结出来，自行研究的一种方法， 实践证明是一种比较正确方便的方法，并且可以不破坏叶轮而得到。
一、泵叶轮叶片测绘
1.叶片绘型的一些基本知识

(1)叶片工作面和背面:离心泵的叶片，一般都是后弯叶片， 如图7-1(b) 所示，朝着旋转方向的将能量传递给液体的叶片表面称工作面，相对应的反面称为叶片背面。

(2)轴面: 经过叶轮轴心线的平面称为抽面，如图7-1(b)中的0-0、0-1、0-2、3-0 ....等平面。
    (3)轴面投影图:将叶轮的前、后盖板和叶片的进、出口边， 用旋转投影的方法投影到同一轴面上， 例图7-1 (a)称轴面投影图。

(4)轴面截线:某一个轴面与叶片工作面、背面的两条交线称轴面截线。轴面与叶轮工作面的交线称工作面轴面截线，如图7-1 (a) 阴影部分的实线为轴面2 -0的工作面轴面截线。阴影部分的虚线为轴面2-0的背面轴面截线。

对离心泵叶片，轴面截线可分为三种形式:一种是圆柱形叶片，如图7-2 (a) 所示，轴面截线成一条平行于轴线的直线;第二种是斜叶片，如图7-2 (b)所示，轴面截线是一条斜直线;第三种是扭曲叶片，如图7-2 (c)所示，轴面截线是一条曲线。 对圆柱形叶片，只要测出截线上任意点就可以确定其轴面截线， 对于斜叶片，需测出截线上两点(一般为前、后盖板上的两点)就可以确定其轴面极线。面对于扭曲叶片，就必需测出椒线上数点，才能确定轴面截线。
(5)叶片剪裁图(叶片术模图): 叶片模型制作时，有的人习惯用叶片剪裁图(木模图)来制作。叶片剪裁图是一组垂直于叶轮轴心线的平面(或称割面)于叶片工作面和背面的交线(为一条空间曲线) 在平面图上的投影。 用轴面截线可以转给成叶片剪裁图(叶片模型截线)，同样也可以将叶片剪裁图转绘成轴面截线。

用轴面截线绘制叶片剪裁图的方法如下，见图7-3。

①在叶轮叶片的轴面截线图上，作垂直于叶轮轴心线的直线1 -1、2-2、3-3--这些直线实质就是一组垂直于叶轮轴心线的平面，通常称为割面或等高面，它们与叶片的交线就是叶片模型截线。直线1-1、 2 -..可以是等题离的，也可以不等距离的，距离大小视叶片扭曲程度而定，扭曲较大时，距离取得小些。

②作平面投影图，以0点为圆心，作叶轮的外圆，并作中心角为Av的轴面投影线0、1、.... ...40 010~15C. 

③将轴面投影图沿后盖板流线与各叶片工作面截线交点投影到平面图上，又将沿前盖板流线与各叶片工作面截线交点投影到平面图上即为叶片工作面的轮廓曲线。作图方法是:以0点为圆心，以盖板流线与轴面截线的交点到轴心线的垂直距离为半径划弧，与各轴面线的交点用光滑的曲线连接即成叶片工作面的轮廓线。同样方法，可作出叶片背面的轮廓线，布置在另一边。这里要注意的是叶片工作面轮廓线与叶片背面轮廓线左右布置位置与叶片旋转方向的关系。因为从叶轮入口看叶片时，只能看到叶片背面，因此平面视图中叶片背面轮廓线的进口边为叶轮的旋转方向。例图7-3中，从叶轮进口方向看为顺时针旋转。

④作模型截线:例图7-3，1 -1割面的模型截线，1 -1割面与轴面0、I、II的轴面截线相交于c、b、a点，它们到轴心的距离分别为R。、R:、R。，在图7-3 (b)平面投影图上，以0点为圆心，以R。、R、R。为半径分别划弧交于0、1、I轴面于c、b、a点，光滑连接a、b、c,这就是割面1-1叶片背面的模型截线。同样方法，可以作出2-2、3-3、4-4割面叶片背面的模型截线。

同样方法，又可作出叶片工作面的模型截线画于另一边。 这就是叶片截线图或称叶片剪裁图。

叶轮测绘就是要测绘出轴面截线图或叶片截线图。渣浆泵

Mapping of pump impeller and pump body

After the pump is damaged, when the spare parts of the pump cannot be purchased, it can only be solved by field mapping. The mapping of pump is mainly the mapping of pump impeller and pump body, because the impeller and pump body determine the performance of pump, and the mapping of pump impeller and pump body is difficult. It is not only a curved surface, but also a special drawing representation method, so this paper mainly introduces the mapping and drawing method of the hydraulic model of the impeller and the flow passage of the pump body, while the mapping of other parts is the same as that of general mechanical parts, without detailed introduction.

There are many surveying and mapping methods for pump impeller and pump body. The method introduced below is a method that we have summed up from practice and researched by ourselves. It has been proved to be a more correct and convenient method in practice, and it can be obtained without damaging the impeller.

I. mapping of pump impeller blades

1. Some basic knowledge of blade drawing

(1) working face and back face of blade: the blades of centrifugal pump are generally backward curved blades. As shown in Figure 7-1 (b), the surface of the blade that transfers energy to the liquid in the direction of rotation is called the working face, and the corresponding back face is called the back face of the blade.

(2) shaft surface: the plane passing through the impeller shaft axis is called the extraction surface, as shown in 0-0, 0-1, 0-2, 3-0... And other planes in Figure 7-1 (b).

(3) axial projection: the front and rear cover plates of impeller and the inlet and outlet sides of blades are projected on the same axial plane by the method of rotary projection. For example, Figure 7-1 (a) is called axial projection.

(4) axial section line: the two intersecting lines between a certain axial surface and the working surface and the back of the blade are called the axial section line. The intersection line between the shaft surface and the impeller working surface is called the cutting line of the working surface. As shown in Figure 7-1 (a), the solid line of the shaded part is the cutting line of the working surface of the shaft surface 2-0. The dashed line in the shadow part is the back axis section of axis 2-0.

For centrifugal pump blades, the axial section line can be divided into three forms: one is cylindrical blade, as shown in Figure 7-2 (a), the axial section line is a straight line parallel to the axis; the second is inclined blade, as shown in Figure 7-2 (b), the axial section line is an oblique straight line; the third is twisted blade, as shown in Figure 7-2 (c), the axial section line is a curve. For cylindrical blades, as long as any point on the section line is measured, the axial section line can be determined. For inclined blades, two points on the section line (generally two points on the front and rear cover plates) can be measured to determine the axial polar line. In the face of the twisted blade, it is necessary to measure the number of points on the pepper line to determine the axial section.

(5) blade cutting drawing (blade technical model drawing): some people are used to making blade cutting drawing (wood model drawing) when making blade model. The blade cutting drawing is the projection of a set of plane (or cut plane) perpendicular to the axis line of the impeller on the plane of the intersection line (a space curve) between the working face and the back face of the blade. It can be transferred to the blade cutting drawing (blade model cutting line) by using the axial cutting line, and it can also be transferred to the axial cutting line.

The method of drawing blade cutting diagram with axial section is as follows, as shown in Figure 7-3.

① on the sectional drawing of the axial surface of the impeller blade, make lines 1-1, 2-2, 3-3 perpendicular to the axial line of the impeller -- these lines are essentially a group of planes perpendicular to the axial line of the impeller, usually called the cutting surface or the contour surface, and the intersection line between them and the blade is the sectional line of the blade model. The straight lines 1-1, 2 -.. can be equidistant or equidistant. The distance depends on the degree of blade twist. When the twist is large, the distance is smaller.

② make the plane projection drawing, take point 0 as the center, make the outer circle of the impeller, and make the axial projection line 0, 1,...... 40 010 ~ 15C with the center angle of AV

(3) the profile curve of the blade working surface is projected on the plan along the intersection of the streamline of the rear cover plate and the section line of each blade working surface, and on the plan along the intersection of the streamline of the front cover plate and the section line of each blade working surface. The drawing method is as follows: take point 0 as the center, take the intersection point of the streamline of the cover plate and the intercept line of the shaft surface to the vertical distance of the axis line as the radius to draw an arc, and connect the intersection point with each axis line with a smooth curve to form the contour line of the blade working surface. In the same way, the contour line on the back of the blade can be made and arranged on the other side. What should be noted here is the relationship between the left and right position of blade working face contour and blade back contour and blade rotation direction. Because only the back of the blade can be seen when looking at the blade from the impeller inlet, the inlet edge of the blade back contour in the plan view is the rotation direction of the impeller. For example, in Figure 7-3, clockwise rotation is seen from the impeller inlet direction.

④ make model section line: for example, figure 7-3 shows the model section line of cutting plane 1-1. The section lines of cutting plane 1-1 and axis planes 0, I and II intersect at points c, B and a. the distances from them to the axis are respectively R. R:, R. , on the plane projection of figure 7-3 (b), take point 0 as the center, and take R. R, R. Make arc intersection on axis 0, 1, I at points c, B, a for radius respectively, and connect a, B, C smoothly, which is the model section line on the back of blade cutting surface 1-1. In the same way, the model lines on the back of blades with 2-2, 3-3 and 4-4 cutting surfaces can be made.

In the same way, the model section line of blade working face can be drawn on the other side. This is the blade screenshot or blade clipping.

Impeller mapping is to map out the shaft section or blade section. Slurry pump