CN116563842A

CN116563842A - Pipe type identification method

Info

Publication number: CN116563842A
Application number: CN202310521818.7A
Authority: CN
Inventors: 王宇峰; 贾帅; 李永俊; 李鹏举
Original assignee: Syntec Technology Suzhou Co Ltd
Current assignee: Syntec Technology Suzhou Co Ltd
Priority date: 2023-05-10
Filing date: 2023-05-10
Publication date: 2023-08-08

Abstract

The invention discloses a pipe type identification method. The method comprises the following steps: 1) Reading a three-dimensional graph of the pipe; 2) Calculating a bounding box, and adjusting the direction and the position of the pipe; 3) Establishing a tangential plane to obtain a useful contour; 4) Obtaining a head line group and a tail line group, projecting the head line group and the tail line group to an XZ plane, screening according to a two-dimensional graph to obtain a parent tube type, extracting characteristic points and storing; 5) The cutting path is stored. The invention provides a method for efficiently identifying common pipe information and cutting paths, which is characterized in that topology relation is not required to be established by traversing each plane, pipe section information can be obtained by only obtaining projection of a head and tail edge line group in the length direction of a pipe, a mathematical pipe model is established, the cutting paths can be accurately and efficiently identified, subsequent processing operation is convenient, and the method is applicable to common pipes such as round pipes, square pipes and elliptical pipes.

Description

Pipe type identification method

Technical Field

The invention relates to the field of laser cutting, in particular to a pipe type identification method.

Background

In CAM software for laser pipe cutting, the need for identifying a three-dimensional model of a pipe, particularly a complex pipe cutting path, is often encountered, and for such a need, it is generally difficult to respond quickly and efficiently.

The general solution to the requirements is to traverse each plane in the three-dimensional model, establish a corresponding topological relation, screen and merge the planes, and then find the tool path corresponding to the outermost contour. This approach is generally time consuming, especially for complex end-face, hole tubing, where the identification efficiency tends to be low because of the very many planes involved.

Disclosure of Invention

In order to solve the problems, the invention provides a pipe type identification method.

According to one aspect of the present invention, there is provided a pipe type identification method comprising the steps of:

1) Reading a three-dimensional graph of the pipe;

2) Calculating a bounding box, and adjusting the direction and the position of the pipe;

3) Establishing a tangential plane to obtain a useful contour;

4) Obtaining a head line group and a tail line group, projecting the head line group and the tail line group to an XZ plane, screening according to a two-dimensional graph to obtain a parent tube type, extracting characteristic points and storing;

5) The cutting path is stored.

In some embodiments, in step 1), information is obtained for all planes in the three-dimensional model of the tubing, including information for the pipe head, pipe tail, bore sidewall surface, pipe inner surface, and pipe outer surface. It is advantageous in that the range and kind of information of the planes in the three-dimensional model obtained in this step are described.

In some embodiments, in step 2), the bounding box is the smallest bounding box that contains all planes, wherein the longest direction of the default bounding box is the tubing stretch direction. It is beneficial in that the meaning of bounding boxes is described.

In some embodiments, in step 2), when adjusting the direction and position of the tube, the end face center in the tube length direction of the minimum bounding box is moved to the zero point position, and the tube length direction is rotated to the Y-axis direction. It is beneficial to describe the specific steps of adjusting the orientation and position of the tubing.

In some embodiments, in step 3), four tangential planes are established that intersect the contours of all planes. It is beneficial to describe a specific method of establishing a tangent plane.

In some embodiments, in step 3), each profile is screened by three features intersecting the tangent plane, intersecting the line parallel to the Y-axis, and non-parallel to the tangent plane, and the face farther from the Y-axis is selected as the useful profile. It is beneficial to describe the specific features of the useful profile and the manner in which the useful profile is obtained.

In some embodiments, in step 4), all edge groups of the plane are head-to-tail adjacent, and are ordered according to the Y value of the bounding box, and the edge groups with the largest and smallest Y values are the head edge group and the tail edge group. It is beneficial to describe a specific method of obtaining the leading and trailing edge groups.

In some embodiments, in step 4), when the parent tube type is obtained, the round tube and the oval tube are first screened, and then the rectangular tube is screened. This has the advantage that the step of obtaining the type of parent tube is described.

In some embodiments, an inscribed ellipse is constructed with a bounding rectangle of a two-dimensional pattern, if all patterns are contained within the inscribed ellipse, then a circular or elliptical tube is determined, based on whether the bounding box is equal in length and width. The method has the advantages that the concrete mode of screening circular pipes and elliptical pipes is described.

In some embodiments, a ray is drawn from the origin to four corners of the bounding box, and the intersection point of each ray and the two-dimensional graph is obtained, and if the distances from the four intersection points to the origin are the same, the rectangular tube is formed. It is beneficial to describe the specific way of rectangular tube.

Drawings

FIG. 1 is a flow chart of a tubing type identification method according to an embodiment of the present invention;

FIG. 2 is a schematic illustration of a method of identifying a type of tubing in FIG. 1 in which a tangential plane is established;

FIG. 3 is a schematic illustration of a method of identifying a type of tubing to obtain a useful profile as shown in FIG. 1;

FIG. 4 is a schematic diagram of a screening round tube and oval tube of the tube type identification method of FIG. 1;

FIG. 5 is a schematic diagram of a rectangular tube screening method of the type identification method of FIG. 1;

fig. 6 is a schematic diagram of extracted feature points of the pipe type recognition method shown in fig. 1.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings.

As shown in fig. 1, the pipe type identification method comprises the following steps for acquiring pipe section information, establishing a pipe mathematical model and identifying a cutting path, wherein the following steps are mainly included, and are respectively described below.

And a first step of reading a three-dimensional graph of the pipe, so as to obtain information of all planes in a three-dimensional model of the pipe, wherein the information mainly comprises information of a pipe head face, a pipe tail face, a hole side wall face, a pipe inner surface, a pipe outer surface and the like.

And secondly, calculating a bounding box, and adjusting the direction and the position of the pipe.

The bounding box is the smallest bounding box that contains all planes, where the longest direction of the default bounding box is the tubing stretch direction. When the direction and the position of the pipe are adjusted, the center of the end face of the minimum bounding box in the length direction of the pipe is moved to the zero position, and the length direction of the pipe is rotated to one of the directions of the axes (the Y axis is taken), so that the subsequent processing path can be conveniently extracted.

Third, a tangential plane is established to obtain a useful profile.

As shown in fig. 2, four tangential planes are established, each as follows:

the normal vector is (0, BX), and passes through the plane of (0, 0);

the normal vector is (BZ, 0, BX), passing through the plane of (0, 0);

the normal vector is (BZ, 0), and passes through the plane of (0, 0);

the normal vector is (BZ, 0, -BX), passing through the plane of (0, 0).

Wherein BX is the length of the bounding box in the X-axis direction, and BZ is the length of the bounding box in the Z-axis direction.

And the useful profile is the profile that needs to be used when identifying the outer surface of the pipe. Wherein intersecting each tangent plane with the contours of all planes, three features of useful contours can be obtained, namely: intersecting the tangential plane (or most of the hole sidewall surface), intersecting the parallel Y-axis (or small portion of the hole sidewall surface, the tube head surface, and the tube tail surface), and non-parallel to the tangential plane.

After screening for the above features, only the tube inner surface and the tube outer surface remain in the remaining flat surface. As shown in fig. 3, the surface farther from the Y axis is selected at this time, that is, among the profiles 1 and 2, the profile 1 is selected as a useful profile,

and fourthly, obtaining a head line group and a tail line group, projecting the head line group and the tail line group to an XZ plane, screening according to a two-dimensional diagram to obtain a parent tube type, extracting characteristic points and storing.

And all edge groups of the plane are adjacent head and tail, and are ordered according to Y values of the bounding boxes, wherein the edge groups with the largest and smallest Y values are the head edge group and the tail edge group.

And after the head and tail edge line group shadows are formed on the XZ plane to form a two-dimensional graph, the two-dimensional graph can be used for judging the pipe interface information according to the two-dimensional graph, so that the type of the parent pipe is obtained through screening. Wherein, first screening pipe and oval pipe, then screening rectangular pipe.

When screening round pipes and oval pipes, constructing an inscribed ellipse by using surrounding rectangles of two-dimensional patterns, if all patterns are contained in the inscribed ellipse, then judging whether the round pipes or the oval pipes are equal according to the length and the width of the surrounding boxes.

As shown in fig. 4, the outer rectangle is a surrounding rectangle, the middle dotted line part is an inscribed ellipse, and the inner layer is a two-dimensional graph. Wherein, the two-dimensional figures in (a) are all in the inscribed ellipse and the length and width of the bounding box are unequal, thus being elliptical tubes; (b) The two-dimensional patterns in the two-dimensional pattern matrix are all in the inscribed ellipse, and the length and the width of the bounding box are equal, so the two-dimensional pattern matrix is a circular tube; the two-dimensional patterns in (c) and (d) are not elliptical, and thus are not circular or elliptical.

Then, drawing a ray to four corners of the bounding box through the origin, and solving intersection points of each ray and the two-dimensional graph, wherein if the distances from the four intersection points to the origin are the same, the rectangular pipe is adopted, and otherwise, the rectangular pipe is other pipes, such as a U-shaped pipe and the like.

As shown in fig. 5, (a), the rays L1, L2, L3, L4 in (a) are rectangular pipes because the distances from points a, B, C, D to the origin O are the same as the intersection points of the two-dimensional graph; in the case of (B), the distances from the points a, B, C, and D, which are the intersection points of the two-dimensional patterns, to the origin O are not the same, and thus the rays L1, L2, L3, and L4 are not rectangular pipes.

Then, the feature points are extracted and stored according to the obtained tube shape. As shown in fig. 6, the characteristic points of the circular tube or the elliptical tube are points of intersection of the graph with the X axis and the Z axis, namely points a, B, C and D in the graph.

Finally, the cutting path is stored. The 3D point positions on the edge groups can be unfolded to a 2D plane according to the tubular and size information and stored, so that subsequent process path calculation such as cutter guiding wires can be conveniently carried out

What has been described above is merely some embodiments of the present invention. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit of the invention.

Claims

1. A pipe type identification method is characterized in that: comprises the following steps

1) Reading a three-dimensional graph of the pipe;

3) Establishing a tangential plane to obtain a useful contour;

5) The cutting path is stored.

2. A method of identifying a pipe type according to claim 1, wherein: in step 1), information of all planes in the three-dimensional model of the pipe is obtained, including information of the pipe head, the pipe tail, the hole side wall surface, the pipe inner surface and the pipe outer surface.

3. A method of identifying a pipe type according to claim 2, wherein: in step 2), the bounding box is the smallest bounding box that contains all planes, wherein the longest direction of the default bounding box is the tubing stretch direction.

4. A method of identifying a pipe type according to claim 3, wherein: in step 2), when the direction and position of the tube are adjusted, the center of the end face of the minimum bounding box in the tube length direction is moved to the zero point position, and the tube length direction is rotated to the Y axis direction.

5. A method of identifying a pipe type according to claim 1, wherein: in step 3), four tangential planes are established so as to intersect the contours of all planes.

6. A method of identifying a pipe type according to claim 1, wherein: in step 3), each profile is screened by three features intersecting the tangent plane, intersecting the line parallel to the Y-axis, and non-parallel to the tangent plane, and the face farther from the Y-axis is selected as the useful profile.

7. A method of identifying a pipe type according to claim 1, wherein: in step 4), all edge groups of the plane are adjacent head and tail, and are ordered according to Y values of bounding boxes, and the edge groups with the largest and smallest Y values are the head edge group and the tail edge group.

8. A method of identifying a pipe type according to claim 1, wherein: in step 4), when the type of the parent tube is obtained, the round tube and the oval tube are first screened, and then the rectangular tube is screened.

9. The method for identifying a pipe type according to claim 8, wherein: an inscribed ellipse is constructed by a surrounding rectangle of a two-dimensional graph, if all graphs are contained in the inscribed ellipse, the inscribed ellipse is a circular tube or an elliptical tube, and then whether the circular tube or the elliptical tube is judged according to whether the length and the width of the surrounding box are equal or not.

10. The method for identifying a pipe type according to claim 9, wherein: and drawing a ray to four corners of the bounding box through the origin, and solving intersection points of each ray and the two-dimensional graph, wherein if the distances from the four intersection points to the origin are the same, the bounding box is a rectangular pipe.