关于APPOX BY TOL+LENGTH

请教一下各位高手，在Cimatron里，差不多每一个刀路参数里面，在右下角都有一行APPOX。BY TOL+LENGTH    MAX，TRI，LEN。请问，这个参数是什么意思，该怎样配合使用。谢！

   一般在曲面坡度较小时,使用该选项.

简单讲 使用APPROX. BY TOL + LENGTH 减少过切, 但计算时间长了.

哦，原来如此！！ 多谢斑竹

darkbit,我的理解没有太大的问题吧。

还有一些注意点
  
Approximation Surface Milling Option Notes:
Milling is done in three stages:
  
1.
Surfaces are approximated by triangular planes whose vertices lie on the parametric curves of the surface.
  
2.
It is possible to control the approximation both by the surface tolerance and by the triangle length. The triangles will be created according to the tolerance, but will not be larger than the defined length. This option should be used to improve the surface quality of surfaces with a large radius of curvature.
  
3.
Milling is done on the triangles which approximate the surface.
Enter SRF. TOL, the maximum distance permitted between each triangular plane and the surface. The smaller the tolerance value, the longer the execution time.

对这问题兄弟们不要瞎猜了，我的解释应该对的，可能我没说清。下面抄一段CIM附带的HELP中的原文，请参考：
  
APPROX. BY TOL.
Select this option to determine the maximum allowable deviation between the surface and the triangular planes used for surface approximation.
  
APPROX. BY TOL + LENGTH
The approximation process will be executed according to the more stringent of the two criteria.
For example, both criteria are needed for approximating a long, nearly horizontal surface curved along a large radius.

这个参数对加工时，加工公差和对造型公差设定相差时应用这个参数会起到更好地逼近加工设的公差的作用我是这样理解的！

还有别的意思？
  
我的理解是 你设计时候的精度是否和长度有关系，应该做什么样的计算
  
不知道理解可不可以

by len 是为高速洗准备的
普通机床用BY TOL 旧可以了