粗糙度 ra 标准是什么
Ra 3.2=表面光洁度6级。
Ra是美国标准的粗糙度符号。
表面光洁度是表面粗糙度的旧标准,它们的对应关系:
1、表面光洁度14级=Ra 0.012,表面光洁度13级=Ra 0.025,表面光洁度12级=Ra 0.050
2、表面光洁度11级=Ra 0.1,表面光洁度10级=Ra 0.2,表面光洁度9级=Ra 0.4
3、表面光洁度8级=Ra 0.8,表面光洁度7级=Ra 1.6,表面光洁度6级=Ra 3.2
4、表面光洁度5级=Ra 6.3,表面光洁度4级=Ra 12.5,表面光洁度3级=Ra 25
5、表面光洁度2级=Ra 50,表面光洁度1级=Ra 100
以上表面粗糙度单位均为μm,即微米=10^-6米。
扩展资料
表面粗糙度对零件的影响主要表现在以下几个方面:
1、影响耐磨性。表面越粗糙,配合表面间的有效接触面积越小,压强越大,摩擦阻力越大,磨损就越快。
2、影响配合的稳定性。对间隙配合来说,表面越粗糙,就越易磨损,使工作过程中间隙逐渐增大;对过盈配合来说,由于装配时将微观凸峰挤平,减小了实际有效过盈,降低了连接强度。
3、影响疲劳强度。粗糙零件的表面存在较大的波谷,它们像尖角缺口和裂纹一样,对应力集中很敏感,从而影响零件的疲劳强度。
4、影响耐腐蚀性。粗糙的零件表面,易使腐蚀性气体或液体通过表面的微观凹谷渗入到金属内层,造成表面腐蚀。
5、影响密封性。粗糙的表面之间无法严密地贴合,气体或液体通过接触面间的缝隙渗漏。
6、影响接触刚度。接触刚度是零件结合面在外力作用下,抵抗接触变形的能力。机器的刚度在很大程度上取决于各零件之间的接触刚度。
7、影响测量精度。零件被测表面和测量工具测量面的表面粗糙度都会直接影响测量的精度,尤其是在精密测量时。
参考资料:百度百科-表面粗糙度
参考资料:百度百科-ra(美国标准的粗糙度符号)
轮廓算术平均偏差Ra是指在曲阳长度L内,轮廓偏距绝对值的算术平均值。
表面粗糙度(surface roughness)是指加工表面具有的较小间距和微小峰谷的不平度[1] 。其两波峰或两波谷之间的距离(波距)很小(在1mm以下),它属于微观几何形状误差。表面粗糙度越小,则表面越光滑。 表面粗糙度一般是由所采用的加工方法和其他因素所形成的,例如加工过程中刀具与零件表面间的摩擦、切屑分离时表面层金属的塑性变形以及工艺系统中的高频振动等。由于加工方法和工件材料的不同,被加工表面留下痕迹的深浅、疏密、形状和纹理都有差别。 表面粗糙度与机械零件的配合性质、耐磨性、疲劳强度、接触刚度、振动和噪声等有密切关系,对机械产品的使用寿命和可靠性有重要影响。一般标注采用Ra。 相关的规范有“GB/T 1031-2009《表面结构 轮廓法 表面粗糙度参数及其数值》”和“GB/T 131-2006 (ISO 1302:2002)《表面结构的表示法》”。
这是中国国家标准,是针对于表面粗糙的标准,还有rx,ry等,建议找<机械设计手册>,上面有详细的介绍!
轮廓算术平均偏差值。
是中国国家标准,《机械制图》中有详细内容介绍。
看来英文的标准还是有的啊
ASME Y14.36M-1996
ISO 1302:2001
In the United States, surface finish is usually specified based on the ASME Y14.36M-1996 standard. Other standards also exist, including ISO 1302:2001.
Roughness Parameters
Each of the roughness parameters is calculated using a formula for describing the surface.
There are many different roughness parameters in use, but Ra is by far the most common. Other common parameters include Rz, Rq, and Rsk. Some parameters are used only in certain industries or within certain countries. For example, the Rk family of parameters is used mainly for cylinder bore linings, and the Motif parameters are used primarily within France.
Since these parameters reduce all of the information in a profile to a single number, great care must be taken in applying and interpreting them. Small changes in how the raw profile data is filtered, how the mean line is calculated, and the physics of the measurement can greatly affect the calculated parameter.
By convention every 2D roughness parameter is a capital R followed by additional characters in the subscript. The subscript identifies the formula that was used, and the R means that the formula was applied to a 2D roughness profile. Different capital letters imply that the formula was applied to a different profile. For example, Ra is the arithmetic average of the roughness profile, Pa is the arithmetic average of the unfiltered raw profile, and Sa is the arithmetic average of the 3D roughness.
Each of the formulas listed in the tables assumes that the roughness profile has been filtered from the raw profile data and the mean line has been calculated. The roughness profile contains n ordered, equally spaced points along the trace, and yi is the vertical distance from the mean line to the ith data point. Height is assumed to be positive in the up direction, away from the bulk material.
粗糙度 ra 标准是什么视频
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