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Chapter6 Surface Roughness 表面粗糙度

Chapter6 Surface Roughness 表面粗糙度. Surface roughness 表面粗糙度概念 Evaluation parameters for surface roughness 表面粗糙度评定参数 Symbols of surface roughness 表面粗糙度的符号 Marking the roughness 表面粗糙度在图样中的标注 Selecting the roughness value 表面粗糙度数值的选用 Exercises 练习题. Surface Roughness 表面粗糙度概念.

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Chapter6 Surface Roughness 表面粗糙度

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  1. Chapter6 Surface Roughness表面粗糙度 Surface roughness 表面粗糙度概念 Evaluation parameters for surface roughness 表面粗糙度评定参数 Symbols of surface roughness 表面粗糙度的符号 Marking the roughness 表面粗糙度在图样中的标注 Selecting the roughness value 表面粗糙度数值的选用 Exercises练习题

  2. SurfaceRoughness表面粗糙度概念 The microscopic geometrical property formed by the small clearance and the rise and fall on the machined surface is called surface roughness. 零件加工表面上具有的较小间距和峰谷所形成的微观几 何形状特性称为表面粗糙度。

  3. Yi Yn Evaluation parameters for surface roughness 表面粗糙度评定参数 （1）Contour arithmetic mean deviation Ra轮廓算术平均偏差Ra Ra is the absolute arithmetic mean of contour deviated distance (distance between each point of the contour surface and the base line ox) within a sample range of the part surface.Ra是在零件表面的一段取样长度内,轮廓偏 距y（表面轮廓上点至基准线Ox的距离）的绝对值的算术平均值。 Ra =1/L Ra

  4. Evaluation parameters for surface roughness 表面粗糙度评定参数 （2） Ten-point height average Rz微观不平度十点高度Rz Rzis defined as the sum of average of 5 contour peak heights and the average of 5 contour bottom depths.Rz是在取样长度内,5个最大轮廓峰高的平均值与5个最大轮廓谷深的平均值之和。 Rz （3）Maximum contour height Ry轮廓最大高度Ry Ryis defined as the distance within the sample length from the peak line to the bottom line.Ry是在取样长度内,轮廓峰顶线和轮廓谷底线之间的距离。 Ry Rz

  5. Symbols of surface roughness表面粗糙度的符号 （1）The surface roughness symbol表面粗糙度的符号 The surface is treated by removing the material. 用去除表层金属方法获得 The surface is obtained without removing the material. 用不去除表层金属的方法获得 Basic symbol基本符号 （2）The location for specifying the surface roughness and related symbols表面粗糙度数值及有关规定在符号中注写的位置 a: Code and value of roughness height (unit: µm);Ra的最大允许值,若写为a1/a2则为最 大允许值/最小允许值;Ra字母可省,若是Rz或Ry时, 应在数值前注明Rz或Ry(单位:m)。 b: Machining requirements, plating, coating, surface treatment, or other requirements. 加工方法代号(如：车、铣、镀涂或其他表面处理等)。 c: Sample length(unit: mm)or waves (unit: µm);取样长度(单位:mm)。 d: Symbolof machining veins;加工纹理方向符号(如：M等)。 e: Allowance(unit: mm) ;加工余量(单位:mm)。 f: Clearance value of roughness (unit: mm) or contour supporting length rate. 粗糙度间距参数值(单位:mm)或轮廓支承长度率。

  6. Marking the roughness表面粗糙度在图样中的标注 • In the same drawing, one surface is only marked once with related symbol (code). It should be marked on contours, dimension lines, dimension boundaries or their extension lines and should be as close as possible to related dimension lines. • 在同一图样中, 每一表面一般只标注一次粗糙度代（符）号, 应注在可见 • 轮廓线、尺寸线、尺寸界线或它们的延长线上, 并尽可能靠近有关尺寸线。 • The tip of roughness symbol should point to the surface from outside and should touch the surface contours. • 粗糙度符号的尖端必须从材料外指向零件表面，并与表面轮廓接触上。 • Roughness symbol should be moveable or revolvable in accordance • with position variation, but shouldn’t be turned over or be distorted. The • number size of roughness value should be the same as that of • dimensions. It is moveable or revolvable in accordance with roughness • symbol and is in accordance with its dimension direction. • 粗糙度符号可随加工表面的位置不同平移或旋转，但不能翻转和变形； • 粗糙度数值中数字的大小应与同一图样的尺寸数字一致，可随粗糙度符号旋 • 转而旋转，但应与该处尺寸标注的方向一致。 • If various surfaces require the same roughness, the most common symbols can be marked on the top-right corner and with ‘The rest’. • 多个表面具有相同粗糙度要求时，对其中使用最多的一种代（符）号， • 可以统一标注在图纸的右上角，并加注“其余”字样。 5) If there are various requirements on the same surface, fine solid line is required to represent their boundary lines, and related roughness symbol (code) and dimension should be shown. 一表面上有不同要求时，需用细实线画出其分界线，并标注相应粗糙度代 （符）号和尺寸。 若全部表面的粗糙 度相同，则可直接 在图的右上角注明

  7. 字头向上或向左 SurfaceRoughness表面粗糙度 无论符号的方向怎么变化，其形状不变 符号尖端从材料外指向其表面

  8. 用简单符号或字母表示不同的加工纹理方向 纹理方向。 SurfaceRoughness表面粗糙度

  9. SurfaceRoughness表面粗糙度 英国某公司图纸

  10. Selecting the roughness value表面粗糙度数值的选用 （1）Ra values and their corresponding machining methods 表面粗糙度的表面特征及其经济加工方法

  11. Selecting the roughness value表面粗糙度数值的选用 （2）Principles for selecting surface roughness parameters 表面粗糙度参数值的选用原则 1) The first series is preferred.选用优先采用的数值。 2) parameters on working surfaces are smaller than that on non-working surfaces. Parameters on the moving surface are smaller than on still surfaces.工作表面比非工作表面参数值小, 运动表面比静止表面参数值小。 3) Select parameters according to production cost. Surface roughness should be as large as possible to reduce machining cost, provided design or usage requirements are met.在满足设计或使用要求的前提下， 其表面粗糙度的参数值尽可能大，以降低加工成本。

  12. Exercises练习题 1. Point out the surface roughnesssymbols which are incorrectly. 找出图中粗糙度代号标注方法上的错误并改正之。 2. Indicate the surface roughnesssymbols. 在图中标注表面粗糙度。

  13. 缺少其余“字样”，位置应放到图的右上方 粗糙度符号的尖端应与表面接触上 Ra应省略 12.5 数字字头应向左 12.5 (milled) 铣字应注在横线上 同一表面重复标注, 且字头不应向下 12.5 分界线应为细实线 粗糙度符号的长边画错 粗糙度符号的尖端应从材料外指向表面 12.5 1.Point out the surface roughnesssymbols which are incorrectly. 找出图中粗糙度代号标注方法上的错误并改正之。 (milled)

  14. 25 其余 3.2 6.3 2×8 12.5 2. Indicate the surface roughnesssymbols. 在图中标注表面粗糙度。 20孔的表面粗糙度为Ra3.2,8孔的表面粗糙度为Ra6.3， 底面的表面粗糙度为Ra12.5，其余表面均为Ra25。  20

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