Method for calculating limit speed of double NURBS paths in free-form surface machining

A curved surface processing and limit speed technology, applied in the direction of electrical program control, digital control, etc., can solve the problem that the machining accuracy of the tool cannot be uniquely determined, and achieve the effect of avoiding the decline of workpiece accuracy, smoothing the rotation speed of the tool shaft, and smoothing the moving speed

Pending Publication Date: 2020-10-02
TIANJIN UNIV
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Problems solved by technology

Langeron[4] proposed to use two NURBS curves to fit the tool axis point and the tool center point trajectory to generate the tool machining path respectively. The double NURBS curves generated by this method are not equidistant, so the tool posture cannot be uniquely determined to affect the machining accuracy

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  • Method for calculating limit speed of double NURBS paths in free-form surface machining
  • Method for calculating limit speed of double NURBS paths in free-form surface machining
  • Method for calculating limit speed of double NURBS paths in free-form surface machining

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Embodiment Construction

[0029] The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

[0030] The present invention protects a method for calculating the limit speed of double NURBS paths in free-form surface processing, see Figure 6 , as follows: 1. Generate equidistant dual NURBS toolpaths

[0031](101) tool tip point fitting curve;

[0032] For the known discrete tool nose data points, the 3-degree NURBS curve can be written according to the definition and properties of the B-spline curve:

[0033]

[0034] Among them, u i Indicates the parameter value of the i-th interpolation point, u i+1 Indicates the parameter value of the i+1th interpolation point, u indicates that in [u i ,u i+1 ] parameter values ​​in the range, p j Indicates the jth control vertex,...

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Abstract

The invention discloses a method for calculating the limit speed of a double NURBS path in free-form surface processing. The method comprises the following steps: (1) calculating a control vertex anda node vector of an NURBS curve according to data points of a known discrete tool nose file, defining a fitting curve of a tool nose point track, calculating data points (cutter axis points for short)participating in cutting in the cutter axis direction through a linear relation, and defining a fitting curve of a track of the point by using the same method, so as to generate the double NURBS path; and (2) solving the curve length of an interpolation road section on a definition domain by integrating a first-order guide vector function of a tool nose point NURBS fitting curve, traversing the whole processing path, and calculating a key point of which the curvature radius reaches a local extreme value under the limitation of geometric error constraint and kinematics constraint so as to obtain the limit speed at the key point.

Description

technical field [0001] The invention belongs to the field of numerical control processing, and in particular relates to a calculation method for the limit speed of double NURBS paths in free-form surface processing. Background technique [0002] The development of key fields such as aerospace equipment and high-end manufacturing equipment has put forward urgent requirements for efficient and high-precision manufacturing of key complex parts, manufacturing quality evaluation and control technology. These complex parts are often constructed from complex surfaces, and the geometric quality of these complex surfaces directly affects the performance of the corresponding functional parts. NURBS path planning is one of the core technologies of NC machining. At present, only a few foreign companies such as Japan's FANUC, Germany's SIEMENS and HEIDENHAIN have mastered relatively complete key technologies of NURBS tool paths. Research on key numerical control technical issues includi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G05B19/416G05B19/4103G05B19/19
CPCG05B19/416G05B19/4103G05B19/19
Inventor 何改云吕逸倩桑一村姚成霖王偲潼
Owner TIANJIN UNIV
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