POST-PROCESSING METHOD FOR SPECIAL SEVEN-FIVE AXIS LINKAGE MACHINE TOOL

Abstract

The present invention discloses a post-processing method for a special seven-five axis linkage machine tool, comprising: building a multi-body kinematic model according to the structure of the machine tool, and building the multi-body kinematic model according to the sequence of workpiece-turntable-machine tool-cross beam-ram-milling head-cutting tool; establishing position coordinate transformation matrices according to the built multi-body kinematic model to obtain the matrices of cutter location points and tool orientation vectors; solving transformation equations of every motion axis of the machine tool and cutter location point coordinates according to the matrices of cutter location points and tool orientation vectors; building a corresponding relationship between the cutter location point coordinates and every motion axis of the machine tool based on a geometric level, and solving specific values of C-axis rotation angle of milling head and C2-axis rotation angle of the turntable.

Claims

1. A post-processing method for a special seven-five axis linkage machine tool, comprising the following specific steps: step 1: building a multi-body kinematic model according to the structure of the machine tool, and building the multi-body kinematic model according to the sequence of workpiece-turntable-machine tool-cross beam-ram-milling head-cutting tool; step 2: establishing position coordinate transformation matrices according to the multi-body kinematic model built in step 1 to obtain the matrices of cutter location points and tool orientation vectors; step 3: solving transformation equations of every motion axis of the machine tool and cutter location point coordinates according to the matrices of cutter location points and tool orientation vectors; step 4: building a corresponding relationship between the cutter location point coordinates and every motion axis of the machine tool based on a geometric level, and solving specific values of C-axis rotation angle of milling head and C2-axis rotation angle of the turntable; wherein step 4 comprises the following substeps: S1. extracting cutter location point coordinates comprising cutter contact point coordinate (x,y,z) and the tool orientation vector (i,j,k) from a tool path of machining a propeller in CAM software, and measuring a distance between the coordinate point and workpiece coordinate origin to obtain the offset distances of CL.sub.X, CL.sub.Y and CL.sub.Z in X, Y and Z direction in world coordinate system (WCS); S2. measuring and recording the distances between tool setting position coordinate and workpiece coordinate origin after configuring each axis of the machine tool in CAM machining simulation software to obtain the offset distances of ML.sub.X, ML.sub.Y and ML.sub.Z in X, Y and Z direction along the machine tool coordinate system; S3. establishing a geometric map for CL.sub.X, CL.sub.Y, CL.sub.Z, ML.sub.X, ML.sub.Y, ML.sub.Z, cutter contact point coordinate (x, y, z), B-axis rotation angle β of milling head, C-axis rotation angle θ.sub.1 of milling head, rotation angle θ.sub.2 of the turntable and displacements of gantry machine tool linear axes (Y-axis and Z-axis), wherein the geometric map is comprised of two parts: the map in XY plane and YZ plane in machine tool coordinate system; S4. establishing formulas of parameters based on the geometric map, to obtain the relationship between the rotation angle θ.sub.2 of the turntable and C-axis rotation angle θ.sub.1 of the milling head; S5. substituting the relationship between the rotation angle θ.sub.2 of the turntable and the C-axis rotation angle θ.sub.1 of the milling head into the transformation equations of every motion axis of the machine tool and cutter location point coordinates in step 3 to obtain the function equation expression of motion of each axis of the machine tool.

Description

DESCRIPTION OF DRAWINGS

[0019] FIG. 1 is a flow chart of a post-processing method for a special seven-five axis linkage machine tool.

[0020] FIG. 2 is a geometric map of relationships of machine tool motion axes, cutter contact point coordinates and offset distances.

DETAILED DESCRIPTION

[0021] The present invention is described below in detail in combination with drawings and embodiments.

[0022] Aiming at the drawbacks of the existing post-processing method for a special seven-five axis linkage machine tool, the present invention proposes a post-processing method for a special seven-five axis linkage machine tool, to solve the problem that the C-axis rotation angle of the milling head and the C2-axis rotation angle of the turntable cannot be solved separately in solving inverse kinematic for three rotary axes and two linear axes, to generate the NC code for machining the propeller for use by the numerical control machine tool.

[0023] The present invention adopts the technical solution: a post-processing method for a special seven-five axis linkage machine tool comprises the following specific steps:

[0024] step 1: building a multi-body kinematic model according to the structure of the machine tool, and building the multi-body kinematic model according to the sequence of workpiece-turntable-machine tool-cross beam-ram-milling head-cutting tool;

[0025] step 2: establishing position coordinate transformation matrices according to the multi-body kinematic model built in step 1 to obtain the matrices of cutter location points and tool orientation vectors;

[0026] step 3: solving transformation equations of every motion axis of the machine tool and cutter location point coordinates according to the matrices of cutter location points and tool orientation vectors;

[0027] step 4: building a corresponding relationship between the cutter location point coordinates and every motion axis of the machine tool based on a geometric level, and solving specific values of C-axis rotation angle of milling head and turntable rotation (C2-axis) angle.

[0028] Step 4 comprises the following substeps:

[0029] S1. extracting cutter location point coordinates comprising cutter contact point coordinate (x,y,z) and the tool orientation vector (i,j,k) from a tool path of machining a propeller in CAM software, and measuring a distance between the coordinate point and workpiece coordinate origin to obtain the offset distances of CL.sub.X, CL.sub.Y and CL.sub.Z in X, Y and Z direction in world coordinate system (WCS);

[0030] S2. measuring and recording the distances between tool setting position coordinate and workpiece coordinate origin after configuring each axis of the machine tool in CAM machining simulation software to obtain the offset distances of ML.sub.X, ML.sub.Y and ML.sub.Z in X, Y and Z direction along the machine tool coordinate system;

[0031] S3. establishing a geometric map for CL.sub.X, CL.sub.Y, CL.sub.Z, ML.sub.X, ML.sub.Y, ML.sub.Z, cutter contact point coordinate (x, y, z), B-axis rotation angle β of milling head (B/C type of milling head as an example here), C-axis rotation angle θ.sub.1 of milling head, rotation angle θ.sub.2 of turntable and displacements of gantry machine tool linear axes (Y-axis and Z-axis) (Y and Z axis gantry machine tool as an example here), wherein the geometric map is comprised of two parts: the map in XY plane and YZ plane in machine tool coordinate system;

[0032] S4. establishing formulas of parameters based on the geometric map, to obtain the relationship between the rotation angle θ.sub.2 of the turntable and C-axis rotation angle θ.sub.1 of the milling head;

[0033] S5. substituting the relationship between the rotation angle θ.sub.2 of the turntable and the C-axis rotation angle θ.sub.1 of the milling head into the transformation equations of every motion axis of the machine tool and cutter location point coordinates in step 3 to obtain the function equation expression of motion of each axis of the machine tool.

[0034] Compared with the prior, the present invention has beneficial effects as follows:

[0035] The present invention is a post-processing method for a special seven-five axis linkage machine tool, which provides a post-processing method for the machine tool with three rotary axes and two linear axes. The existing conventional post-processing method for the machine tool cannot solve the C-axis rotation angle of the milling head and the C2-axis rotation angle of the turntable. The post-processing method provided by the present invention takes dimension parameters of the machine tool and the milling head in to consideration from the view of the geometric level, simply and effectively solves the problem of calculating the C-axis rotation angle of the milling head and the C2-axis rotation angle of the turntable, and provides a method for post-processing for the machine tool with three rotary axes and two linear axes.