阅读说明：本技术 一种五自由度混联机器人模具抛光系统及方法 (Five-degree-of-freedom hybrid robot mold polishing system and method ) 是由 肖聚亮 张通 黄田 刘海涛 孙誉博 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种五自由度混联机器人模具抛光方法,该方法为：基于模具的三维CAD模型图,导出刀触点的位置坐标,设S<Sub>ij</Sub>为第i条轨迹线段上的第j个刀触点,以刀触点{S<Sub>ij</Sub>,S<Sub>ij+1</Sub>,S<Sub>i-1j</Sub>}、{S<Sub>ij</Sub>,S<Sub>i-1j</Sub>,S<Sub>ij-1</Sub>}、{S<Sub>ij</Sub>,S<Sub>ij-1</Sub>,S<Sub>i+1j</Sub>}、{S<Sub>ij</Sub>,S<Sub>i+1j</Sub>,S<Sub>ij+1</Sub>}组成四个相邻的三角形,求得每个三角形的单位法向量<Image he="91" wi="498" file="DDA0002563772550000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>设向量<Image he="80" wi="82" file="DDA0002563772550000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>的中点为H<Sub>1</Sub>,设<Image he="82" wi="82" file="DDA0002563772550000013.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>的中点为H<Sub>2</Sub>,设向量<Image he="82" wi="98" file="DDA0002563772550000014.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>的中点为O,设S<Sub>ij</Sub>的单位法向量为n<Sub>ij</Sub>近似为<Image he="159" wi="121" file="DDA0002563772550000015.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>由此获得刀触点的姿态数据。本发明还公开了一种五自由度混联机器人模具抛光系统。本发明可以精确地确定机器人抛光器具的位姿数据及刀位点轨迹。(The invention discloses a polishing method for a five-degree-of-freedom hybrid robot mold, which comprises the following steps: deriving position coordinates of the tool contact based on the three-dimensional CAD model drawing of the mould, and setting S ij For the jth knife contact on the ith trace segment, with knife contact { S ij ，S ij+1 ，S i‑1j }、{S ij ，S i‑1j ，S ij‑1 }、{S ij ，S ij‑1 ，S i+1j }、{S ij ，S i+1j ，S ij+1 Four adjacent triangles are formed, and the unit normal vector of each triangle is obtained Let vector quantity Has a midpoint of H 1 Is provided with Has a midpoint of H 2 Let a vector The midpoint of (A) is O, set to S ij Has a unit normal vector of n ij Is approximated to Attitude data of the blade contact is thus obtained. The invention also discloses a five-degree-of-freedom hybrid robot mold polishing system. The invention can accurately determine the pose data and the tool location point track of the robot polishing tool.)

1. A polishing method for a five-degree-of-freedom hybrid robot mold is characterized by comprising the following steps:

step 1, establishing a workpiece coordinate system based on a three-dimensional CAD model drawing of a mould; defining the contact point of the polishing tool and the workpiece as a knife contact point, wherein the knife contact point track comprises a plurality of track line segments, and L is set_iIs the ith track segment, i is 1,2,3, …, m; l is₁～L_mThe projections on the XY plane of the workpiece coordinate system are straight lines which are parallel to each other; let S_ijJ is the j-th blade contact on the ith trace segment, and j is 1,2,3, …, n; deriving tool contact S from three-dimensional CAD model drawing_ijThe position coordinates of (a);

step 2, taking the j-1 st knife contact S on the ith track line segment_ij-1J th knife contact S_ijThe j +1 th knife contact S_ij+1Taking the (i-1) th stripJ th knife contact S on track line segment_i-1jTaking the jth knife contact S on the ith +1 track line segment_i+1jI-2, 3, …, m-1, j-2, 3, …, n-1; are respectively expressed by { S_ij，S_ij+1，S_i-1j}、{S_ij，S_i-1j，S_ij-1}、{S_ij，S_ij-1，S_i+1j}、{S_ij，S_i+1j，S_ij+1The vertex of the triangle is correspondingly formed into four adjacent triangles, and the unit normal vector of each triangle is obtained

and 3, defining the center of the polishing tool as a tool location point, and converting the position and posture data of the tool contact into the position and posture data of the tool location point which can be identified by the hybrid robot control system.

2. The five-degree-of-freedom hybrid robot mold polishing method according to claim 1, further comprising the following steps before step 3: calculating the track line segment L of two adjacent knife contacts_iAnd L_i+1The maximum value of the normal vector included angles is theta_maxWhen theta is_maxAbove a given threshold, L is reserved_i+1Contact point of knife in (1), otherwise delete L_i+1The blade contact of (1).

3. The five-degree-of-freedom hybrid robot mold polishing method according to claim 1, further comprising the following steps before step 3: get sword contact orbit line segment L_iThree adjacent track points S on_ij-1、S_ij、S_ij+1J ═ 2,3, …, n-1; calculating the point S_ijTo line segment S_ij-1S_ij+1Distance of (2), set point S_ijTo line segment S_ij-1S_ij+1D, if d is less than a given threshold value, the blade contact S is retained_ijOtherwise, delete the knife contact S_ij。

4. The five-degree-of-freedom hybrid robot die polishing method according to claim 1, wherein the step 3 comprises the following substeps:

step 3-1, set α as knife contact S_ijAt an angle of rotation of the axis of the polishing implement about the X-axis of the workpiece coordinate system, let β be the tool contact point S_ijThe angle of rotation of the axis of the polishing tool about the Y axis of the workpiece coordinate system; then there are:

blade contact S obtained in step 2_ijα and β values are obtained by using a normal vector;

let matrix K be knife contact S_ijThe matrix expression of the position and posture matrix of (2) is:

wherein Px, Py and Pz correspond to the blade contact S_ijX, Y, Z coordinates in the workpiece coordinate system;

step 3-2, setting a knife contact S_ijThe unit normal vector of (a) is rotated by an angle psi around the Y-axis of the workpiece coordinate system, and the distance of the radius r of the polishing tool is moved along the Z-axis direction to become a corresponding tool contact S_ijThe unit normal vector of the tool location point; let Q be the corresponding knife contact S_ijThe matrix of the positions and attitudes of the tool positions in (a) then has Q K × T, where T is the transformation matrix:

and 3-3, converting the matrix Q into position coordinates and posture data of the knife location point which can be identified by the hybrid robot control system, and further generating a track point file of the knife location point.

5. The five-degree-of-freedom hybrid robot die polishing method according to claim 4, wherein a robot start-stop, feed speed and interpolation instruction are added to a track point file for generating a tool location point to form a complete processing file, and the processing file is copied to a robot control system.

6. The five-degree-of-freedom hybrid robot mold polishing method according to claim 1, wherein step 3 further comprises the steps of: establishing a relation between the workpiece coordinate system and the robot terminal coordinate system, offsetting the origin of the robot terminal coordinate system to the position of the origin of the workpiece coordinate system, and storing the offset into the robot control system.

7. The five-degree-of-freedom hybrid robot die polishing method according to claim 1, wherein a pitch of the trajectory line segment is not more than 6 mm.

8. A five-degree-of-freedom hybrid robot mold polishing system for implementing the five-degree-of-freedom hybrid robot mold polishing method according to any one of claims 1 to 7, comprising: the polishing machine comprises a hybrid robot body and a floating main shaft arranged on the hybrid robot body, wherein a polishing disc is arranged on the floating main shaft, and the axis of the floating main shaft is vertical to the surface of the polishing disc.

9. The five-degree-of-freedom hybrid robot mold polishing system according to claim 8, wherein the floating main shaft is a pneumatic floating main shaft, a proportional pressure regulating valve is further provided on the hybrid robot body, and the pneumatic floating main shaft is communicated with an air source through the proportional pressure regulating valve.

10. The five degree-of-freedom series-parallel robot mold polishing system of claim 8, wherein a substrate of the polishing disk is sandpaper, wool, or deer skin.

Technical Field

The invention relates to a die polishing system and a die polishing method, in particular to a die polishing system and a die polishing method of a five-degree-of-freedom hybrid robot.

Background

Polishing is a common mechanical finishing process, the important purpose of which is to achieve the required surface roughness. The polishing process can not only increase the smoothness of the polished surface, but also improve the surface quality and improve the local stress concentration phenomenon.

The surface of the mould is mostly a complex free-form surface, so that most enterprises are still in the manual polishing stage of workers in the current mould polishing, the defects that the processing efficiency is low, the mould processing precision is low, and the consistency of the surface quality is difficult to ensure exist, and the processing quality is very dependent on the experience and skill of technical workers and is difficult to achieve the technical requirements. The robot polishing can replace manual polishing to obtain the required workpiece surface roughness. In essence, robotic polishing techniques are equivalent to digitizing, quantifying, and controlling the motion of the polishing head by a control system, the experience and skill of the process technician. The robot polishing technology adopts a polishing head to process, on one hand, good fit with the surface of a processed workpiece can be realized, and on the other hand, the advantages of high repeated positioning precision and high execution speed of the hybrid robot can be fully exerted. Because the molds are mostly complex free-form surfaces, it is difficult to accurately determine pose data and tool location point tracks of a robot polishing tool such as a polishing disk or a polishing wheel, and a better mold surface cannot be processed.

Disclosure of Invention

The invention provides a five-degree-of-freedom hybrid robot mold polishing system and a method for accurately determining pose data and tool location point tracks of a robot polishing tool to solve the technical problems in the prior art.

The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows: a polishing method for a five-degree-of-freedom hybrid robot mold comprises the following steps:

step 1, establishing a workpiece coordinate system based on a three-dimensional CAD model drawing of a mould; defining the contact point of the polishing tool and the workpiece as a knife contact point, wherein the knife contact point track comprises a plurality of track line segments, and L is set_iIs the ith track segment, i is 1,2,3, …, m; l is₁～L_mThe projections on the XY plane of the workpiece coordinate system are straight lines which are parallel to each other; let S_ijJ is the j-th blade contact on the ith trace segment, and j is 1,2,3, …, n; deriving tool contact S from three-dimensional CAD model drawing_ijThe position coordinates of (a);

step 2, taking the j-1 st knife contact S on the ith track line segment_ij-1J th knife contact S_ijThe j +1 th knife contact S_ij+1Taking the jth knife contact S on the ith-1 track line segment_i-1jTaking the jth knife contact S on the ith +1 track line segment_i+1jI-2, 3, …, m-1, j-2, 3, …, n-1; are respectively expressed by { S_ij，S_ij+1，S_i-1j}、{S_ij，S_i-1j，S_ij-1}、{S_ij，S_ij-1，S_i+1j}、{S_ij，S_i+1j，S_ij+1The vertices of the triangles are correspondingly formed into four adjacent triangles,finding the unit normal vector of each triangleLet vector quantityHas a midpoint of H₁Is provided withHas a midpoint of H₂Let a vectorThe midpoint of (A) is O, set to S_ijHas a unit normal vector of n_ijThen n is_ijIs approximated to

When i is 1, S_1jUnit normal vector of (S)_2jThe unit normal vector of (1); when i is m, S_mjUnit normal vector of (S)_m-1jThe unit normal vector of (1); when j is 1, S_i1Unit normal vector of (S)_i2The unit normal vector of (1); when j is n, S_inUnit normal vector of (S)_in-1The unit normal vector of (1); the unit normal vector of the knife contact is the attitude data of the knife contact;

and 3, defining the center of the polishing tool as a tool location point, and converting the position and posture data of the tool contact into the position and posture data of the tool location point which can be identified by the hybrid robot control system.

Further, step 3 is preceded by the following steps: calculating the track line segment L of two adjacent knife contacts_iAnd L_i+1The maximum value of the normal vector included angles is theta_maxWhen theta is_maxAbove a given threshold, L is reserved_i+1Contact point of knife in (1), otherwise delete L_i+1The blade contact of (1).

Further, step 3 is preceded by the following steps: get sword contact orbit line segment L_iThree adjacent track points S on_ij-1、S_ij、S_ij+1J ═ 2,3, …, n-1; calculating the point S_ijTo line segment S_ij-1S_ij+1Distance of (2), set point S_ijTo line segment S_ij-1S_ij+1D, if d is less than a given threshold value, the blade contact S is retained_ijOtherwise, delete the knife contact S_ij。

Further, step 3 comprises the following sub-steps:

step 3-1, set α as knife contact S_ijAt an angle of rotation of the axis of the polishing implement about the X-axis of the workpiece coordinate system, let β be the tool contact point S_ijThe angle of rotation of the axis of the polishing tool about the Y axis of the workpiece coordinate system; then there are:

blade contact S obtained in step 2_ijα and β values are obtained by using a normal vector;

let matrix K be knife contact S_ijThe matrix expression of the position and posture matrix of (2) is:

wherein Px, Py and Pz correspond to the blade contact S_ijX, Y, Z coordinates in the workpiece coordinate system;

step 3-2, setting a knife contact S_ijThe unit normal vector of (a) is rotated by an angle psi around the Y-axis of the workpiece coordinate system, and the distance of the radius r of the polishing tool is moved along the Z-axis direction to become a corresponding tool contact S_ijThe unit normal vector of the tool location point; let Q be the corresponding knife contact S_ijThe matrix of the positions and attitudes of the tool positions in (a) then has Q K × T, where T is the transformation matrix:

and 3-3, converting the matrix Q into position coordinates and posture data of the knife location point which can be identified by the hybrid robot control system, and further generating a track point file of the knife location point.

And further, adding a robot start-stop, feed speed and interpolation instruction into a track point file for generating a tool position point to form a complete processing file, and copying the processing file into a robot control system.

Further, step 3 further comprises the following steps: establishing a relation between the workpiece coordinate system and the robot terminal coordinate system, offsetting the origin of the robot terminal coordinate system to the position of the origin of the workpiece coordinate system, and storing the offset into the robot control system.

Furthermore, the distance between the track line segments is less than or equal to 6 mm.

The invention also provides a five-degree-of-freedom hybrid robot die polishing system for implementing the five-degree-of-freedom hybrid robot die polishing method, which comprises the following steps: the polishing machine comprises a hybrid robot body and a floating main shaft arranged on the hybrid robot body, wherein a polishing disc is arranged on the floating main shaft, and the axis of the floating main shaft is vertical to the surface of the polishing disc.

Furthermore, the floating main shaft is a pneumatic floating main shaft, a proportional pressure regulating valve is further arranged on the hybrid robot body, and the pneumatic floating main shaft is communicated with an air source through the proportional pressure regulating valve.

Further, the base material of the polishing disk is sand paper, wool or deer skin.

The invention has the advantages and positive effects that:

the die polishing method provided by the invention can accurately determine the pose data and the tool location point track of the robot polishing device, the tool axis vector and the track point normal vector form a certain angle during polishing, and the soft polishing wheel is adopted, so that after a certain pressure is applied to the polishing wheel, the polishing wheel is changed from point polishing to surface polishing, thereby obviously eliminating tool marks and greatly improving the processing quality of the die surface.

The invention adopts the 5-freedom-degree parallel-serial robot for processing, the robot has large reachable working space and high repeated positioning precision,

the invention adopts the self-adaptive adjustment of the track line segment distance, and ensures the processing efficiency on the premise of ensuring the processing precision.

The invention adopts the pneumatic floating main shaft to realize constant-force polishing, improves the problems of poor quality and poor consistency of the polished surface and improves the quality and the precision of the polished surface.

Drawings

FIG. 1 is a schematic view of a five-DOF hybrid robot mold polishing system;

FIG. 2 is a schematic diagram of a tool contact trajectory of a workpiece;

FIG. 3 is a schematic view of polishing of a polishing pad.

In the figure, 1-workbench, 2-mould, 3-polishing disc, 4-floating spindle, 5-hybrid robot body, 6-control system and 7-control cabinet.

Ψ is the angle of rotation of the unit normal vector of the tool contact about the Y-axis of the workpiece coordinate system, and r is the polishing implement radius.

Detailed Description

For further understanding of the contents, features and effects of the present invention, the following embodiments are enumerated in conjunction with the accompanying drawings, and the following detailed description is given:

referring to fig. 1 to 3, a method for polishing a five-degree-of-freedom hybrid robot mold includes the following steps:

step 1, establishing a three-dimensional model of a mould 2 by adopting three-dimensional CAD software, and establishing a workpiece coordinate system based on a three-dimensional CAD model drawing of the mould 2; the three-dimensional model of the mold 2 can be established through three-dimensional drawing software such as Por/E, MasterCAM, UG, CAXA manufacturing engineers and the like, a polishing path parallel to the X axis of the workpiece coordinate system is arranged in the three-dimensional model drawing, and then the position coordinates of each knife contact point in the polishing path under the workpiece coordinate system are directly derived through the three-dimensional drawing software.

The polishing mould 2 of the polishing device such as a polishing disk, a polishing wheel and the like can be adopted, the contact point of the polishing device and the workpiece is defined as a knife contact point, the track of the knife contact point comprises a plurality of track line segments, and L is set_iIs the ith track segment, i is 1,2,3, …, m; l is₁～L_mThe projections on the XY plane of the workpiece coordinate system are straight lines which are parallel to each other; let S_ijJ is the j-th blade contact on the ith trace segment, and j is 1,2,3, …, n; deriving tool touch from three-dimensional CAD model drawingPoint S_ijThe position coordinates of (a); let the knife contact position coordinate be denoted as S_ij(X, Y and Z), wherein X is the X-axis value of the robot coordinate system, Y is the Y-axis value of the robot coordinate system, and Z is the Z-axis value of the robot coordinate system.

Step 2, taking the j-1 st knife contact S on the ith track line segment_ij-1J th knife contact S_ijThe j +1 th knife contact S_ij+1Taking the jth knife contact S on the ith-1 track line segment_i-1jTaking the jth knife contact S on the ith +1 track line segment_i+1jI-2, 3, …, m-1, j-2, 3, …, n-1; are respectively expressed by { S_ij，S_ij+1，S_i-1j}、{S_ij，S_i-1j，S_ij-1}、{S_ij，S_ij-1，S_i+1j}、{S_ij，S_i+1j，S_ij+1The vertex of the triangle is correspondingly formed into four adjacent triangles, and the unit normal vector of each triangle is obtained

Let vector quantity

Has a midpoint of H₁Is provided withHas a midpoint of H₂Let a vectorThe midpoint of (A) is O, set to S_ijHas a unit normal vector of n_ijThen n is_ijIs approximated toWhen i is 1, S_1jUnit normal vector of (S)_2jThe unit normal vector of (1); when i is m, S_mjUnit normal vector of (S)_m-1jThe unit normal vector of (1); when j is 1, S_i1Unit normal vector of (S)_i2The unit normal vector of (1); when j is n, S_inUnit normal vector of (S)_in-1The unit normal vector of (1); knife contact unitThe normal vector is the attitude data of the tool contact.

And 3, defining the center of the polishing tool as a tool location point, and converting the position and posture data of the tool contact into the position and posture data of the tool location point which can be identified by the hybrid robot control system 6.

Further, step 3 may also include the following steps before: calculating the track line segment L of two adjacent knife contacts_iAnd L_i+1The normal vector angle of two points with the same X coordinate value, i is 1,2, …, m-1; let the maximum value of the included angles of the normal vectors be theta_maxWhen theta is_maxAbove a given threshold, L is reserved_i+1Contact point of knife in (1), otherwise delete L_i+1The blade contact of (1). By deleting the path line segment of the contact point of the cutter, the self-adaptive adjustment of the line spacing is realized, and the processing efficiency can be ensured on the premise of ensuring the processing precision.

Further, step 3 may also include the following steps before: get sword contact orbit line segment L_iThree adjacent track points S on_ij-1、S_ij、S_ij+1I is 1,2,3, …, m; j ═ 2,3, …, n-1; calculating the point S_ijTo line segment S_ij-1S_ij+1Distance of (2), set point S_ijTo line segment S_ij-1S_ij+1D, if d is less than a given threshold value, the blade contact S is retained_ijOtherwise, delete the knife contact S_ij. By deleting the knife contact points in the track line segment, redundant points of the track can be removed, data simplification is realized, and the processing efficiency is improved.

Further, step 3 may comprise the following substeps:

step 3-1, set α as knife contact S_ijAt an angle of rotation of the axis of the polishing implement about the X-axis of the workpiece coordinate system, let β be the tool contact point S_ijThe angle of rotation of the axis of the polishing tool about the Y axis of the workpiece coordinate system; then there are:

blade contact S obtained in step 2_ijα and β values are obtained from the normal vector.

Let matrix K be knife contact S_ijThe matrix expression of the position and posture matrix of (2) is:

wherein Px, Py and Pz correspond to the blade contact S_ijX, Y, Z coordinates in the object coordinate system.

Step 3-2, setting a knife contact S_ijThe unit normal vector of (a) is rotated by an angle psi around the Y-axis of the workpiece coordinate system, and the distance of the radius r of the polishing tool is moved along the Z-axis direction to become a corresponding tool contact S_ijThe unit normal vector of the tool location point; let Q be the corresponding knife contact S_ijThe matrix of the positions and attitudes of the tool positions in (a) then has Q K × T, where T is the transformation matrix:

and 3-3, converting the matrix Q into position coordinates and posture data of the knife location point which can be identified by the hybrid robot control system 6, and further generating a track point file of the knife location point.

The difference between the main shaft vector of the generated track point and the normal vector of the discrete point of the curved surface of the die 2 is a fixed angle psi, and in addition, the constant pressure in the machining process is ensured by controlling the constant pressure of the floating main shaft 4 cylinder, so that the machining quality of the workpiece is better ensured.

Further, a robot start-stop, feed speed and interpolation instruction can be added to the track point file for generating the tool location point to form a complete processing file, and the processing file is copied to the robot control system 6.

Further, step 3 may further include the steps of: and establishing a relation between the workpiece coordinate system and the robot terminal coordinate system, offsetting the original point of the robot terminal coordinate system to the position of the original point of the workpiece coordinate system, and storing the offset into the robot control system 6.

Furthermore, the distance between the track line segments can be less than or equal to 6 mm. The distance between the track line segments refers to the distance between the projection line segments of two adjacent track line segments on the XY plane of the workpiece coordinate system, the linear distance between two adjacent points on the same track is defined as the step length, and the distance between the track line segments and the set step length are small in size, so that the calculated normal vector can be more accurate, and the machining precision of the complex curved surface is improved.

The invention also provides an embodiment of a five-degree-of-freedom hybrid robot mold polishing system adopting the five-degree-of-freedom hybrid robot mold polishing method, and the system comprises: the polishing machine comprises a hybrid robot body 5, a control system 6 for controlling the hybrid robot body 5 to operate, a floating main shaft 4 arranged on the hybrid robot body 5, a polishing disc 3 arranged on the floating main shaft 4, and the axis of the floating main shaft 4 is vertical to the surface of the polishing disc 3. The control system 6 is arranged in a control cabinet 7, and the mould 2 is placed on the working table 1.

The floating main shaft 4 can be a pneumatic floating main shaft, a proportional pressure regulating valve can be further arranged on the hybrid robot body, and the pneumatic floating main shaft is communicated with an air source through the proportional pressure regulating valve. The pressure of the proportional valve is adjusted by the control system 6, so that the pressure of the cylinder of the floating main shaft 4 and the rotating pressure of the main shaft are controlled. The pneumatic floating main shaft is an air pressurization type floating main shaft, and the pressure of a cylinder 4 of the floating main shaft and the rotating pressure of the main shaft are changed by adjusting the air pressure.

Further, the base material of the polishing pad 3 may be sandpaper, wool, deer skin, or the like. Due to the adoption of the soft polishing wheel, after a certain pressure is applied to the polishing wheel, the polishing wheel is changed from point polishing to surface polishing, so that the knife lines can be obviously eliminated, and the processing quality of the surface of the die is greatly improved.

The working principle of the invention is further illustrated below by a preferred embodiment of the invention:

step 1: a three-dimensional model of the die 2 is established by adopting three-dimensional CAD software, a polishing path parallel to the X axis of a workpiece coordinate system is arranged in the three-dimensional model, and the position coordinates of each knife contact in the polishing path under the workpiece coordinate system and the posture data of the knife contact are obtained.

And establishing a three-dimensional model of the die 2 through three-dimensional CAD software such as Por/E, MasterCAM, UG and CAXA manufacturing engineers, establishing a workpiece coordinate system, enabling the transverse direction of the die 2 to be parallel to the X axis of the workpiece coordinate system, enabling the longitudinal direction of the die 2 to be parallel to the Y axis of the workpiece coordinate system, and enabling the Z axis of the workpiece coordinate system to be vertical to the plane of the workbench. A three-dimensional model of the die 2 is established through three-dimensional drawing software, and then the position coordinates of each knife contact in the polishing path under a workpiece coordinate system are directly derived through the three-dimensional drawing software.

Is provided with L_iIs the ith track segment, i is 1,2,3, …, m; l is₁～L_mThe projections on the XY plane of the workpiece coordinate system are straight lines which are parallel to each other; let S_ijJ is the j-th blade contact on the ith trace segment, and j is 1,2,3, …, n. Obtaining the corresponding tool contact S from the three-dimensional model of the die 2_ijPosition vector p of_ij。

Step 2: acquiring attitude data of a knife contact, specifically comprising the following steps:

step 2-1, taking the j-1 th knife contact S on the ith track line segment_ij-1J th knife contact S_ijThe j +1 th knife contact S_ij+1Taking the jth knife contact S on the ith-1 track line segment_i-1jTaking the jth knife contact S on the ith +1 track line segment_i+1jI-2, 3, …, m-1, j-2, 3, …, n-1; are respectively expressed by { S_ij，S_ij+1，S_i-1j}、{S_ij，S_i-1j，S_ij-1}、{S_ij，S_ij-1，S_i+1j}、{S_ij，S_i+1j，S_ij+1The vertex of the triangle is correspondingly formed into four adjacent triangles, and the unit normal vector of each triangle is obtained

Let vector quantityHas a midpoint of H₁Is provided withHas a midpoint of H₂Let a vector

The midpoint of (A) is O, set to S_ijHas a unit normal vector of n_ijThen n is_ijIs approximated to

When i is 1, S_1jUnit normal vector of (S)_2jThe unit normal vector of (1); when i is m, S_mjUnit normal vector of (S)_m-1jThe unit normal vector of (1); when j is 1, S_i1Unit normal vector of (S)_i2The unit normal vector of (1); when j is n, S_inUnit normal vector of (S)_in-1The unit normal vector of (1); the unit normal vector of the knife contact is the attitude data of the knife contact.

Thus, the position vector p of the contact point of the robot knife can be obtained_ijSum normal vector n_ij。

Step 2-2: calculating the track line segment L of two adjacent knife contacts_iAnd L_i+1In the method, the normal vector included angle of two points with the same X coordinate value is set as theta_maxWhen theta is_maxGreater than a given threshold value theta_sThen, L is reserved_i+1Contact point of knife in (1), otherwise delete L_i+1The blade contact of (1). In addition, limiting conditions are set simultaneously, so that the distance between two adjacent paths is not more than 6 mm.

Step 2-3: get a single path L_iThree adjacent track points S on_ij-1、S_ij、S_ij+1(j-2, 3, …, n-1), calculate point S_ijTo line segment S_ij-1S_ij+1Is recorded as d, if d is smaller than a given threshold value d_sThen the middle knife contact S is reserved_ijOtherwise, the middle knife contact S is removed_ij. Traversal of path L in this way_iAll the trace points on.

And step 3: and acquiring the attitude data of the tool location point, and converting the position and attitude data of the tool contact into the position and attitude data of the tool location point which can be identified by the hybrid robot control system.

Step 3-1, set α as knife contact S_ijAt an angle of rotation of the axis of the polishing implement about the X-axis of the workpiece coordinate system, let β be the tool contact point S_ijAbout the axis of the polishing toolThe angle of rotation of the Y axis of the coordinate system; then there are:

blade contact S obtained in step 2_ijα and β values are obtained by using a normal vector;

let matrix K be knife contact S_ijThe matrix expression of the position and posture matrix of (2) is:

wherein Px, Py and Pz correspond to the blade contact S_ijX, Y, Z coordinates in the workpiece coordinate system;

step 3-2, setting a knife contact S_ijThe unit normal vector of (a) is rotated by an angle psi around the Y-axis of the workpiece coordinate system, and the distance of the radius r of the polishing tool is moved along the Z-axis direction to become a corresponding tool contact S_ijKnife location point G_ijThe unit normal vector of (1); let Q be the corresponding knife contact S_ijKnife location point G_ijThen Q is K × T, where T is the transformation matrix:

and 3-3, converting the matrix Q into position coordinates and posture data of the knife location point which can be identified by the hybrid robot control system 6, and further generating a track point file of the knife location point. Converting the obtained position coordinates and posture data of the tool position point into a data format of the position coordinates and posture of the tool position point which can be recognized by the hybrid robot control system 6, such as G_ij(X, Y, Z, A, B). And connecting the track points in sequence to form a polishing track path of the robot.

And 4, step 4: and adding related instructions such as robot start-stop, feed speed, air inlet valve opening and closing, interpolation and the like into the generated track point file of the tool location point to form a complete processing file which can be identified by the robot control system 6.

And 5: the robot is powered up, the air pump is opened, and the process file is copied to the robot control system 6.

Step 6: establishing a relation between a mold workpiece coordinate system and a robot tail end coordinate system, shifting the robot tail end coordinate system to the position of the origin of the workpiece coordinate system, and recording the offset to the corresponding position of the control system 6.

And 7: the cylinder pressure of the floating main shaft 4 is set to 0.15MPa by the control system 6, and the rotation pressure of the floating main shaft 4 is set to 0.63 MPa.

And 8: and operating the machining instruction to enable the tail end of the robot to move according to the preset path track until the set workpiece machining is completed.

And step 9: and returning the robot to the zero point, powering down the robot control system 6 and closing the air pump.

The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to carry out the same, and the present invention shall not be limited to the embodiments, i.e. the equivalent changes or modifications made within the spirit of the present invention shall fall within the scope of the present invention.