CN109333165B - A kind of grinding method of the non-circular bend glass ornaments based on point cloud data description - Google Patents

Abstract

The present invention relates to a kind of grinding method of non-circular bend glass ornaments based on point cloud data description.The present invention controls the linkage data of workpiece rotational motion and longitudinal tracking feeding by determining, processes to arbitrarily non-circular bend glass workpiece external form profile.The present invention only need to can obtain the linkage data of control workpiece rotational motion and longitudinal tracking feeding according to glass pieces contour point data and the structural parameters of numerically-controlled machine tool.Whether there is or not determining mathematical models can be applicable in for profile, and grinding accuracy is high, and error is small.The disadvantages of preferably overcoming the cumbersome mapping for acquiring special-shaped non-circular profile machining locus by geometrograph in engineering, heavy workload, also overcomes the method for curve matching, and there are error of fitting, formula calculates complicated disadvantage.

Description

A grinding method for non-circular curved glass ornaments based on point cloud data description

technical field

The invention belongs to the technical field of glass ornaments grinding, and relates to a grinding method for non-circular surface glass ornaments described based on point cloud data.

Background technique

Glass is a hard, brittle, transparent material whose optical and physical properties play a vital role in many different industrial applications. Nowadays, all kinds of glass ornaments are widely used in people's daily life. The demand for special-shaped glass ornaments is increasing. However, the traditional processing methods are relatively backward. Glass molds of complex shapes. The manufacturing efficiency and precision of this type of method depend on the experience of technicians, and the degree of automation is low, which can no longer meet the market demand. In addition, for the engineering of grinding and processing special-shaped non-circular rotary parts, geometric drawing is usually used to determine the linkage coordinate point positions of the rotary axis (C axis) and the longitudinal axis (Y axis) one by one. The drawing is cumbersome and the workload is heavy. The other is the method of curve fitting, but this method has fitting errors, and the formula is complicated and the calculation is large. Since non-circular surface grinding technology directly involves the core technology and commercial interests of CNC manufacturers, there are few literatures on non-circular surface grinding models and processes at home and abroad.

With the development of science and technology and industry, the demand for precision manufacturing of various components is increasing, and the numerical control technology is also constantly innovating. Grinding processing is developing towards high speed, high precision and high productivity. For the plane special-shaped non-circular contour, it can be either the contour expressed by the definite mathematical model or the contour given by the discrete point cloud data. Non-circular grinding generally refers to the grinding process in which the trajectory of the grinding point is a non-circular curve in the CNC grinding process. The grinding point tracking technology of C-X axis synchronous grinding is usually adopted. The headstock of the grinding machine is a technology in which the C axis drives the workpiece to rotate, and the grinding wheel frame is a technology in which the X axis tracks the grinding point according to the instructions of the headstock. Using computer numerical control technology, according to the contour shape of the workpiece, the corresponding numerical control program is programmed to control the linkage of the lateral tracking feed (X axis) of the grinding wheel and the rotation (C axis) of the workpiece to process and form the required outline. This full numerical control grinding method can realize rapid processing of products only by changing the numerical control program for different products, and overcomes the problems of easy wear of the mold, difficulty in guaranteeing precision, long production cycle, and difficult operation in traditional processing methods. A series of defects such as cumbersome drawing and heavy workload have the advantages of high precision, high efficiency and high flexibility.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the prior art and the characteristics of glass non-circular surface processing, to provide a non-circular surface glass jewelry grinding method based on point cloud data description, according to the coordinate point data describing the contour shape of the workpiece, using the method based on The grinding point search method of the binary search method is used to obtain the grinding point, so as to obtain the linkage data for controlling the rotary (C-axis) movement of the workpiece and the longitudinal tracking feed (Y-axis).

To achieve the above object, the present invention adopts the following technical solutions:

Including the following steps:

Step 1: Determine the linkage data for controlling the C-axis movement of the workpiece rotation and the Y-axis for longitudinal tracking feed. Specific steps are as follows:

(1), the equation of the outer circle of the known grinding wheel is: (xX)^2+(y-Y')^2=R^2, where: (X, Y') is the coordinate of the grinding wheel center O ₁ , R is the radius of the grinding wheel; store the coordinate point data describing the contour of the workpiece in the array Array1, and store the coordinates of the first coordinate point into the end of the array again, and the length of the array is k. Let i be the subscript of the array, i=0,1,2,3,...,k-1, the initial position i=0; the coordinate of the workpiece center O is (X, Y), from which each workpiece can be calculated L _i and θ _i corresponding to the coordinate points of the contour: where L _i is the distance from the coordinate point of each workpiece contour to the workpiece center O, Lmax is the maximum value among all L _i , and Lmin is the minimum value among all L _i , θ _i is the angle between the line connecting each coordinate point to the workpiece center O and the line connecting the previous coordinate point to the workpiece center, θ ₀ =0. Copy the array Array1 to the array Array2.

⑵. Perform rotation processing on all coordinate point data in the array Array2:

Rotate all the coordinate points in the array Array2 counterclockwise around the center of the workpiece, the rotation angle is θ _i corresponding to the i-th coordinate point, and obtain a new set of coordinate points ( _xi ', y _i ') through the coordinate rotation formula, and Store the calculation result in the backup array Array3. After the rotated coordinates of all the points in the array Array2 are calculated, the array Array3 is copied to the array Array2, and then go to step (3). The calculation formula of the rotated coordinates ( _xi ', y _i ') is shown in formula (1) and formula (2):

x _i '=(x _i -X)*cosθ _i -(y _i -Y)*sinθ _i +X (1);

y _i '=(x _i -X)*sinθ _i +(y _i -Y)*cosθ _i +Y (2);

⑶. Calculate respectively the center ordinates Y ₁ , Y ₂ , Y ₃ of the grinding wheel during the movement of the grinding wheel along the axis, where Y ₁ =YL _i -R, Y ₂ =Y-Lmax-R; the initial value of Y ₁ is Obtained according to Li corresponding to the _i -th coordinate point in the array _Array1 , its value is the vertical coordinate Y of the workpiece center minus Li, and then minus the radius R of the grinding wheel; the initial value of Y ₂ is a certain value, and its value is the center of the workpiece The ordinate Y minus Lmax, and then minus the grinding wheel radius R; Y ₃ is the average of Y ₁ and Y ₂ .

(4) Calculate the value d of the proximity of the grinding wheel:

Y ₃ ＝(Y ₁ +Y ₂ )/2, after substituting, the equation of the circle (xX)^2+(yY ₃ )^2=R^2 is obtained, and the expression of the value d for judging the proximity between the workpiece and the grinding wheel is as follows: (3):

d=(xX)^2+(yY ₃ )^2-R^2 (3);

If there are coordinate points such that d<0, it means that the contour of the workpiece intersects with the outer circle of the grinding wheel; if all points make d>0, it means that the contour of the workpiece is separated from the outer circle of the grinding wheel; when d=0, it means that the contour of the workpiece and the outer circle of the grinding wheel Tangent; when |d| is approximately equal to 0, it indicates that the contour of the workpiece is approximately tangent to the outer circle of the grinding wheel;

(5) Substitute all coordinate points ( _xi ', y _i ') in Array2 into formula (3) respectively, and obtain the minimum value dmin of d.

When |dmin|>Δ, Δ is a value set according to the error requirement. When this condition is satisfied, the corresponding point at this time is considered to be an approximate tangent point. The smaller Δ is set, the smaller the error will be, but the corresponding calculation amount will be larger, adjust the value of Δ according to the error requirements; if dmin<0, set Y ₁ =Y ₃ , and turn to step (4 ); as dmin>0, make Y ₂ =Y ₃ , and turn to step (4);

When |dmin|<=Δ, the ordinate Y ₃ of the grinding wheel center at this time is assigned to Y _i ', which is the required result, and skips to step (6);

(6) According to the ordinate Y _i ' obtained from the calculation result of step (5), calculate the distance D _i from the center of the workpiece O to the center of the grinding wheel at this time, that is, D _i =YY _i '. According to the calculated angle θ _i between D _i and the workpiece rotating around its center, the linkage data for controlling the C-axis movement of the workpiece rotation and the Y-axis for longitudinal tracking feed are determined.

When i=k-1, it means that all the grinding points have been determined at this time, and proceed to step (7); otherwise, proceed to step (2) to rotate the next coordinate point data;

(7) At the end, all the grinding points are obtained.

Step 2. Grinding the outline of any non-circular curved glass ornament to be processed according to the linkage data obtained in step 1 to control the workpiece rotation C-axis movement and longitudinal tracking feed Y-axis.

Compared with the prior art, the method of the present invention has the beneficial effect that the control of workpiece rotation (C axis) motion and longitudinal tracking feed (Y axis) can be obtained only according to the contour point data of the glass workpiece and the structural parameters of the numerically controlled machine tool. ) linkage data. It can be applied with or without a definite mathematical model on the contour, with high grinding precision and small error. It better overcomes the disadvantages of cumbersome drawing and heavy workload in engineering to obtain the machining trajectory of special-shaped non-circular contours by geometric drawing method, and also overcomes the shortcomings of curve fitting method, which has fitting errors and complicated formula calculations .

Description of drawings

Fig. 1 is the position relationship figure of emery wheel and workpiece profile in the grinding process of the present invention;

Fig. 2 is a schematic diagram of coordinate rotation;

Fig. 3 is a schematic diagram of the outline of the grinding wheel gradually approaching the grinding point.

Detailed ways

The present invention is described below in conjunction with accompanying drawing.

As shown in Figures 1 to 3, a non-circular curved glass jewelry grinding method based on point cloud data is used to process any non-circular curved glass workpiece. The number 1 in the figure is a non-circular curved glass workpiece, and 2 is a grinding wheel. , O is the center of the workpiece, O ₁ is the center of the grinding wheel.

Step 1: Determine the linkage data for controlling the C-axis movement of the workpiece rotation and the Y-axis for longitudinal tracking feed. Specific steps are as follows:

(1), the equation of the outer circle of the known grinding wheel is: (xX)^2+(y-Y')^2=R^2, where: (X, Y') is the coordinate of the grinding wheel center O ₁ , R is the radius of the grinding wheel; store the coordinate point data describing the contour of the workpiece in the array Array1, and store the coordinates of the first coordinate point into the end of the array again, and the length of the array is k. Let i be the subscript of the array, i=0,1,2,3,...,k-1, the initial position i=0; the coordinate of the workpiece center O is (X, Y), from which each workpiece can be calculated L _i and θ _i corresponding to the coordinate points of the contour: where L _i is the distance from the coordinate point of each workpiece contour to the workpiece center O, Lmax is the maximum value among all L _i , and Lmin is the minimum value among all L _i , θ _i is the angle between the line connecting each coordinate point to the workpiece center O and the line connecting the previous coordinate point to the workpiece center, θ ₀ =0. Copy the array Array1 to the array Array2.

⑵. Perform rotation processing on all coordinate point data in the array Array2:

Rotate all the coordinate points in the array Array2 counterclockwise around the center of the workpiece, the rotation angle is θ _i corresponding to the i-th coordinate point, and obtain a new set of coordinate points ( _xi ', y _i ') through the coordinate rotation formula, and Store the calculation result in the backup array Array3. After the rotated coordinates of all the points in the array Array2 are calculated, the array Array3 is copied to the array Array2, and then go to step (3). The calculation formula of the rotated coordinates ( _xi ', y _i ') is shown in formula (1) and formula (2):

x _i '=(x _i -X)*cosθ _i -(y _i -Y)*sinθ _i +X (1);

y _i '=(x _i -X)*sinθ _i +(y _i -Y)*cosθ _i +Y (2);

⑶. Calculate respectively the center ordinates Y ₁ , Y ₂ , Y ₃ of the grinding wheel during the movement of the grinding wheel along the axis, where Y ₁ =YL _i -R, Y ₂ =Y-Lmax-R; the initial value of Y ₁ is Obtained according to Li corresponding to the _i -th coordinate point in the array _Array1 , its value is the vertical coordinate Y of the workpiece center minus Li, and then minus the radius R of the grinding wheel; the initial value of Y ₂ is a certain value, and its value is the center of the workpiece The ordinate Y minus Lmax, and then minus the grinding wheel radius R; Y ₃ is the average of Y ₁ and Y ₂ .

(4) Calculate the value d of the proximity of the grinding wheel:

Y ₃ ＝(Y ₁ +Y ₂ )/2, after substituting, the equation of the circle (xX)^2+(yY ₃ )^2=R^2 is obtained, and the expression of the value d for judging the proximity between the workpiece and the grinding wheel is as follows: (3):

d=(xX)^2+(yY ₃ )^2-R^2 (3);

If there are coordinate points such that d<0, it means that the contour of the workpiece intersects with the outer circle of the grinding wheel; if all points make d>0, it means that the contour of the workpiece is separated from the outer circle of the grinding wheel; when d=0, it means that the contour of the workpiece and the outer circle of the grinding wheel Tangent; when |d| is approximately equal to 0, it indicates that the contour of the workpiece is approximately tangent to the outer circle of the grinding wheel;

(5) Substitute all coordinate points ( _xi ', y _i ') in Array2 into formula (3) respectively, and obtain the minimum value dmin of d.

When |dmin|>Δ, Δ is a value set according to the error requirement. When this condition is satisfied, the corresponding point at this time is considered to be an approximate tangent point. The smaller Δ is set, the smaller the error will be, but the corresponding calculation amount will be larger, adjust the value of Δ according to the error requirements; if dmin<0, set Y ₁ =Y ₃ , and turn to step (4 ); as dmin>0, make Y ₂ =Y ₃ , and turn to step (4);

When |dmin|<=Δ, the ordinate Y ₃ of the grinding wheel center at this time is assigned to Y _i ', which is the required result, and skips to step (6);

(6) According to the ordinate Y _i ' obtained from the calculation result of step (5), calculate the distance D _i from the center of the workpiece O to the center of the grinding wheel at this time, that is, D _i =YY _i '. According to the calculated angle θ _i between D _i and the workpiece rotating around its center, the linkage data for controlling the C-axis movement of the workpiece rotation and the Y-axis for longitudinal tracking feed are determined.

When i=k-1, it means that all the grinding points have been determined at this time, and proceed to step (7); otherwise, proceed to step (2) to rotate the next coordinate point data;

(7) At the end, all the grinding points are obtained.

Step 2. Grinding the outline of any non-circular curved glass ornament to be processed according to the linkage data obtained in step 1 to control the workpiece rotation C-axis movement and longitudinal tracking feed Y-axis.

Claims (1)

1. A grinding method based on a non-circular surface glass ornament described by point cloud data, is characterized in that: comprises the steps: Step 1. Determine the linkage data for controlling the C-axis movement of the workpiece rotation and the Y-axis longitudinal tracking feed; the specific steps are as follows: (1), the equation of the outer circle of the known grinding wheel is: (xX)^2+(y-Y')^2=R^2, where: (X, Y') is the coordinate of the grinding wheel center O ₁ , R is the radius of the grinding wheel; store the coordinate point data describing the contour of the workpiece in the array Array1, and store the coordinates of the first coordinate point into the end of the array again, and the length of the array is k; let i be the subscript of the array, i= 0,1,2,3,...,k-1, the initial position i=0; the coordinates of the workpiece center O are (X, Y), from which the corresponding L _i and θ _i : where L _i is the distance from the coordinate point of each workpiece outline to the workpiece center O, Lmax is the maximum value of all L _i , Lmin is the minimum value of all L _i , θ _i is each coordinate point to the workpiece The angle between the connection line of the center O and the connection line between the previous coordinate point and the workpiece center, θ ₀ =0; copy the array Array1 to the array Array2; ⑵. Perform rotation processing on all coordinate point data in the array Array2: Rotate all the coordinate points in the array Array2 counterclockwise around the center of the workpiece, the rotation angle is θ _i corresponding to the i-th coordinate point, and obtain a new set of coordinate points ( _xi ', y _i ') through the coordinate rotation formula, and Store the calculation results in the backup array Array3; after the calculation of the rotated coordinates of all points in the array Array2, copy the array Array3 to the array Array2, and turn to step (3); the rotated coordinates (x _i ', y _i ' ) calculation formula see formula (1) and formula (2): x _i '=(x _i -X)*cosθ _i -(y _i -Y)*sinθ _i +X (1); y _i '=(x _i -X)*sinθ _i +(y _i -Y)*cosθ _i +Y (2); ⑶. Calculate respectively the center ordinates Y ₁ , Y ₂ , Y ₃ of the grinding wheel during the movement of the grinding wheel along the axis, where Y ₁ =YL _i -R, Y ₂ =Y-Lmax-R; the initial value of Y ₁ is Obtained according to Li corresponding to the _i -th coordinate point in the array _Array1 , its value is the vertical coordinate Y of the workpiece center minus Li, and then minus the radius R of the grinding wheel; the initial value of Y ₂ is a certain value, and its value is the center of the workpiece The ordinate Y minus Lmax, and then minus the grinding wheel radius R; Y ₃ is the average value of Y ₁ and Y ₂ ; (4) Calculate the value d of the proximity of the grinding wheel: Y ₃ ＝(Y ₁ +Y ₂ )/2, after substituting, the equation of the circle (xX)^2+(yY ₃ )^2=R^2 is obtained, and the expression of the value d for judging the proximity between the workpiece and the grinding wheel is as follows: (3): d=(xX)^2+(yY ₃ )^2-R^2 (3); If there are coordinate points such that d<0, it means that the contour of the workpiece intersects with the outer circle of the grinding wheel; if all points make d>0, it means that the contour of the workpiece is separated from the outer circle of the grinding wheel; when d=0, it means that the contour of the workpiece and the outer circle of the grinding wheel Tangent; when |d| is approximately equal to 0, it indicates that the contour of the workpiece is approximately tangent to the outer circle of the grinding wheel; (5), all coordinate points ( _xi ', y _i ') in Array2 are substituted in formula (3) respectively, and obtain the minimum value dmin of d; When |dmin|>Δ, Δ is a value set according to the error requirement. When this condition is satisfied, the corresponding point at this time is considered to be an approximate tangent point; the smaller Δ is set, the smaller the error will be, but The larger the corresponding calculation amount, adjust the Δ value according to the error requirements; if dmin<0, set Y ₁ =Y ₃ , and turn to step (4); if dmin>0, set Y ₂ =Y ₃ , And turn to step (4); When |dmin|<=Δ, the ordinate Y ₃ of the grinding wheel center at this time is assigned to Y _i ', which is the required result, and skips to step (6); (6), according to the ordinate Y _i ' obtained from the calculation result of step (5), calculate the distance D _i from the workpiece center O to the center of the grinding wheel at this time, that is, D _i =YY _i '; according to the obtained D _i and the workpiece Rotate the angle θ _i around its center, so as to determine the linkage data for controlling the workpiece rotation C-axis movement and longitudinal tracking feed Y-axis; When i=k-1, it means that all the grinding points have been determined at this time, and proceed to step (7); otherwise, proceed to step (2) to rotate the next coordinate point data; (7), end, get all grinding points; Step 2. Grinding the outline of any non-circular curved glass ornament to be processed according to the linkage data obtained in step 1 to control the workpiece rotation C-axis movement and longitudinal tracking feed Y-axis.