Siemens sinumerik 840D sl Function Manual

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Detailed description2.2 Face millingSpecial functions: 3D Tool Radius Compensation (W5)24 Function Manual, 11/2006, 6FC5397-2BP10-2BA06LQJXODUSRLQWFigure 2-13 Change in the machining point on the tool surface close to a point in which surfacenormal vector and tool orientation are parallelThe problem is basically solved as follows: If the angle d between the surface normal vectorn F and tool orientation w is smaller than a limit value (machine data) δ min, then the side angley on tools with a flat end face (e.g. torus cutter or cylindrical mill) must be 0. This restrictiondoes not apply to tool types with a spherical end face (e.g. ball end mill, die sinker) sinceangular changes close to the singular point do not lead to abrupt changes in the machiningpoint on the surface of such tools. If δ now becomes 0, i.e. the sign of lead angle b changes,the machining point moves from its current position to the opposite side of the tool. Thismovement is executed in an inserted linear block.The machining operation is aborted with an alarm if an attempt is made to machine withinthe illegal angular range for the side angle y (i.e. δ < δ min and γ , 0).The insertion of linear blocks makes it necessary to split the original blocks at the singularpoints. The partial blocks created in this way are treated as if they were original, whichmeans, for example, that a concave path containing a singularity is treated like an insidecorner, i.e. there is no contour violation. Each new partial block must contain at least one toolcontact point since this is always calculated on the basis of adjacent traversing blocks.Singularities do not just occur at isolated points, but along whole curves. This is the case, forexample, if the curve to be interpolated is a plane curve (i.e. a curve with a constantosculating plane) and the tool is constantly aligned in parallel to the binormal vector, i.e.perpendicular to the osculating plane. A simple example is a circular arc in the x-y plane thatis machined by a tool aligned in parallel to the z axis. On paths of this type, the tool offset isreduced to a tool length compensation, i.e. the tool is moved so that its tip FS is positionedon the programmed path.On transition between singular and non-singular curves, linear blocks must be inserted in thesame way as for isolated singular points so that the machining point on the tool can movefrom the tool tip FS to the periphery (on outside corners and convex surfaces) or the pathsmust be shortened to avoid contour violations (on inside corners and concave surfaces).