A kind of intersection line cutting path calculation method

Abstract

This invention discloses a method for calculating the cutting path of an intersection line. The method includes the following steps: 1) establishing mathematical models of the main pipe and branch pipe; 2) obtaining the intersection lines of the outer and inner surfaces of the main pipe and branch pipe respectively, resulting in an outer contour line and an inner contour line; 3) projecting the outer contour line onto the inner surface of the main pipe, resulting in an outer projection line; 4) back-projecting both the outer projection line and the inner contour line onto the outer surface of the main pipe, resulting in an outer path and an inner path; 5) finding the union of the outer path and the inner path to obtain the maximum cutting contour. This invention provides a four-axis pipe cutting machine cutting method using Y and B interpolation of the intersection line. It can be used to cut intersection lines where the angle between the branch pipe and the main pipe is not 90 degrees, when the branch pipe is rotated or offset, or when the branch pipe is a round or square pipe. It eliminates the need for manual cutting of the pipe intersection line, improving processing efficiency and saving processing costs.

Description

Technical Field

[0001] This invention relates to the field of pipe cutting and processing, and in particular to a method for calculating the cutting path of intersecting lines. Background Technology

[0002] Metal pipe fittings have a wide range of applications in modern industrial production, such as in the chemical, sanitary ware, and piping systems industries. Currently, laser pipe cutting machines are commonly used to cut thin metal pipe fittings. While cutting ordinary holes and making cuts on pipes is relatively simple, when connecting pipes, it is necessary to set a cutting intersection line to allow the branch pipe to connect smoothly to the main pipe.

[0003] Most laser tube cutting machines on the market are four-axis tube cutting machines. Their cutting heads have three degrees of freedom (i.e., X-axis, Y-axis and Z-axis). The workpiece is clamped by a chuck and can be rotated through a rotary axis (B-axis).

[0004] The aforementioned types of pipe cutting machines typically employ XY-axis interpolation or YB-axis interpolation for hole cutting. XY-axis interpolation involves keeping the rotating axis stationary while the X and Y axes move to cut the hole. Although this method can cut relatively small 90-degree intersecting holes, it is often difficult to cut the hole properly when the boundary of the intersecting hole is close to the edge of the pipe because the cutting thickness at the edge is inconsistent with the cutting thickness in the middle. Furthermore, when cutting intersecting holes, it is impossible to accurately cut the pipe path, so milling or grinding is required before the branch pipe can be inserted, resulting in low processing efficiency.

[0005] In addition, although a five-axis pipe cutter can be used to achieve better cutting results, it is more expensive and more difficult to operate, resulting in higher costs. Summary of the Invention

[0006] To address the above problems, this invention provides a method for calculating the cutting path of an intersection line.

[0007] According to one aspect of the present invention, a method for calculating the cutting path of an intersection line is provided, comprising the following steps:

[0008] 1) Establish mathematical models for the main pipe and branch pipes;

[0009] 2) Obtain the intersection lines of the outer and inner surfaces of the main pipe and the branch pipe respectively to obtain the outer contour line and the inner contour line;

[0010] 3) Project the outer contour line onto the inner surface of the mother tube to obtain the outer projection line;

[0011] 4) Project both the outer projection line and the inner contour line onto the outer surface of the mother tube to obtain the outer path and the inner path;

[0012] 5) Find the union of the outer path and the inner path to obtain the maximum cutting contour.

[0013] The present invention provides a method for calculating the intersection line cutting path, which is a four-axis pipe cutting machine cutting method using Y and B interpolation of the intersection line. It can be used to cut the intersection line where the angle between the branch pipe and the main pipe is not 90 degrees, the branch pipe is rotated or offset, and the branch pipe is a round or square pipe. It eliminates the need for manual cutting of the pipe intersection line, which not only improves processing efficiency but also saves processing costs.

[0014] In some implementations, in step 1), a mathematical model of the main pipe and the branch pipe is established based on the diameter and thickness of the main pipe, the diameter of the branch pipe, and the angle between the main pipe and the branch pipe. The advantage of this approach is that it describes a specific method for establishing the mathematical model of the main pipe and the branch pipe.

[0015] In some embodiments, in step 2), the intersection line of the outer surfaces of the main pipe and the branch pipe is the outer contour line. The advantage is that a method for obtaining the outer contour line is described.

[0016] In some embodiments, in step 2), the intersection line of the inner surfaces of the main pipe and the branch pipe is the inner contour line. The advantage is that a method for obtaining the inner contour line is described.

[0017] In some implementations, in step 3), the path of the outer contour line is discretized into multiple three-dimensional points, and each three-dimensional point is projected onto the inner surface of the mother tube. The advantage is that a method for obtaining the outer projection line is described.

[0018] In some implementations, in step 4), the paths of the outer projection lines or inner contour lines are discretized into multiple three-dimensional points, and each three-dimensional point and the center point of its corresponding section of the parent tube are used to construct multiple straight lines. The intersection of each straight line with the outer surface of the parent tube is the outer path or inner path. The advantage of this approach is that it describes methods for obtaining the outer and inner paths.

[0019] In some implementations, in step 5), the maximum cutting profile is greater than the size of the solid obtained by Boolean summation of the main pipe and the branch pipe. Its advantage lies in describing the constraint condition for the maximum cutting profile.

[0020] In some implementations, in step 5), YB-axis interpolation is used to cut along the maximum cutting contour. The advantage of this is that it describes a specific cutting method after obtaining the maximum cutting contour. Attached Figure Description

[0021] Figure 1 This refers to the structure of the cutting head of a four-axis pipe cutter in the prior art.

[0022] Figure 2This is a schematic diagram of the mathematical model for establishing a method for calculating the intersection line cutting path according to one embodiment of the present invention.

[0023] Figure 3 for Figure 2 The diagram shows a parent tube surface for calculating the outer and inner contour lines of a method for calculating the intersection line cutting path.

[0024] Figure 4 for Figure 2 The diagram shows a cross-section of the parent tube when back-projecting onto the outer surface of the parent tube, which is a method for calculating the intersection line cutting path.

[0025] Figure 5 for Figure 3 The diagram shows a schematic of the surface of the mother tube, calculated by a method for calculating the cutting path of an intersecting line. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings.

[0027] Figure 1 The structure of the cutting head-related parts of a prior art four-axis pipe cutter is shown. Figure 2 The illustration schematically shows the establishment of a mathematical model for a method of calculating the intersection line cutting path according to an embodiment of the present invention. Figure 3 Showing Figure 2 One method for calculating the intersection line cutting path involves calculating the outer and inner contour lines of the parent tube surface. Figure 4 Showing Figure 2 One method for calculating the intersection line cutting path involves back-projecting the cross-section of the parent pipe onto its outer surface. Figure 5 Showing Figure 2 The surface condition of the mother tube is calculated by a method for calculating the intersection line cutting path.

[0028] like Figure 1 As shown, the cutting head of the four-axis pipe cutter has three degrees of freedom (i.e., X-axis, Y-axis and Z-axis), while the workpiece (also called the mother tube, which includes but is not limited to round tubes) being cut below the cutting head is clamped by a chuck, and the workpiece can be rotated through a rotating axis (B-axis).

[0029] The intersection line cutting path calculation method is used for the above-mentioned four-axis pipe cutting machine, that is, it runs using the X-axis, Y-axis, Z-axis and B-axis, and the corresponding coordinate axes are drawn in each of the attached drawings.

[0030] The calculation method mainly includes two parts: calculating the projection lines and merging the projection lines. Specifically, it can be divided into several steps as described below.

[0031] The first step is to establish mathematical models for the main pipe and branch pipes.

[0032] like Figure 2 As shown, the horizontally positioned section below represents the main pipe to be cut (a circular pipe is used as an example in this embodiment), while the section that can be inserted obliquely into the main pipe is the branch pipe. To calculate the cutting method required for the insertion connection between the two, a mathematical model of the main pipe and the branch pipe needs to be established in space. This mathematical model can be established based on parameters such as the diameter and thickness of the main pipe, the diameter of the branch pipe, and the angle between the main pipe and the branch pipe.

[0033] In the calculation, the main pipe and branch pipe will intersect after Boolean summation. Theoretically, this solid needs to be cut off to connect the main pipe and branch pipe. However, due to the structure of the surrounding cutting machine, more solid material actually needs to be cut off to smoothly insert the branch pipe into the main pipe.

[0034] The second step is to obtain the intersection lines of the outer and inner surfaces of the main pipe and the branch pipe respectively, thus obtaining the outer contour line and the inner contour line.

[0035] like Figure 3 As shown, the intersection lines of the outer and inner surfaces of the main pipe and the branch pipe are calculated respectively. The intersection line of the outer surfaces of the main pipe and the branch pipe is assumed to be the outer contour line (i.e.,...). Figure 3 The solid curve portion in the middle), and the intersection line of the inner surfaces of the main pipe and the branch pipe is set as the inner contour line (i.e. Figure 3 (The dashed curve portion in the text).

[0036] During cutting, because each cutting point is perpendicular to the cylindrical surface of the main pipe and points towards its axis, if only the outer and inner contour lines are cut, interference will still occur when inserting the branch pipe, preventing it from being smoothly inserted into the main pipe. The specific areas requiring cutting need further calculation based on the outer and inner contour lines. For example, the material at the intersection of the outer and inner contour lines also needs to be removed during cutting.

[0037] The third step is to project the outer contour line onto the inner surface of the mother tube to obtain the outer projection line.

[0038] During this projection, the path of the outer contour line is discretized into multiple three-dimensional points, and each three-dimensional point is projected onto the inner surface of the mother tube. The resulting projection line is called the outer projection line.

[0039] Let the radius of the cylindrical surface be R, then its equation is:

[0040] .

[0041] Let the coordinates of a point on the outer contour line be (x, y, z). Then, when projected onto the inner surface, the projected coordinates are (x0, y0, z0), where the x-axis and y-axis coordinates remain unchanged. 0= x, y0 = y, and z0 is calculated as follows:

[0042] .

[0043] The fourth step is to back-project both the outer projection line and the inner contour line onto the outer surface of the mother tube to obtain the outer path and the inner path.

[0044] In this invention, YB axis interpolation cutting is proposed to be used for cutting. In this cutting method, the cutting head and the outer surface of the mother tube are tangent. Therefore, it is necessary to back-project the outer projection line and inner contour line obtained above onto the outer surface of the mother tube to obtain two projection paths, which are called the outer path and the inner path, respectively.

[0045] During this back projection, the external projection line or inner contour line path is discretized into multiple three-dimensional points, and each three-dimensional point is projected onto the outer surface of the mother tube. The specific back projection method is as follows: each three-dimensional point and the center point of the mother tube section where it is located are respectively constructed into multiple straight lines, and the intersection of each straight line with the outer surface of the mother tube is the external path or inner path.

[0046] like Figure 4 As shown, let the coordinates of a certain three-dimensional point be (x1, y1, z1), then the coordinates of the center point of the cross section of the parent pipe where it is located are (0, y1, 0). Connecting the two points can construct a straight line m. The intersection point of the straight line m and the outer surface of the parent pipe, i.e., the point (x2, y1, z2), is the point on the desired outer or inner path.

[0047] Step 5: Calculate the maximum cutting profile.

[0048] like Figure 5 As shown, by taking the union of the outer and inner paths obtained in the above steps, the maximum cutting contour can be obtained, which is the actual cutting path required (i.e., Figure 5 (The curved portion in the diagram). The maximum cut profile is larger than the size of the solid obtained by Boolean summation of the main pipe and branch pipes.

[0049] After obtaining the maximum cutting contour, the YB axis interpolation cutting method is used to cut along the maximum cutting contour. This will ensure that after cutting, the branch pipe is inserted into the main pipe and fits perfectly against the inner surface of the main pipe.

[0050] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for calculating the cutting path of an intersection line, characterized in that: Includes the following steps 1) Establish mathematical models for the main pipe and branch pipes; 2) Obtain the intersection lines of the outer and inner surfaces of the main pipe and the branch pipe respectively to obtain the outer contour line and the inner contour line; 3) Project the outer contour line onto the inner surface of the mother tube to obtain the outer projection line. The path of the outer contour line is discretized into multiple three-dimensional points, and each three-dimensional point is projected onto the inner surface of the mother tube. 4) Project both the outer projection line and the inner contour line onto the outer surface of the mother tube to obtain the outer path and the inner path. The path of the outer projection line or the inner contour line is discretized into multiple three-dimensional points, and each three-dimensional point and the center point of the mother tube section where it is located are respectively constructed into multiple straight lines. The intersection of each straight line with the outer surface of the mother tube is the outer path or the inner path. 5) Find the union of the outer path and the inner path to obtain the maximum cutting contour, and use the YB axis interpolation cutting method to cut along the maximum cutting contour.

2. The method for calculating the cutting path of an intersection line according to claim 1, characterized in that: In step 1), a mathematical model of the main pipe and the branch pipe is established based on the diameter and thickness of the main pipe, the diameter of the branch pipe, and the angle between the main pipe and the branch pipe.

3. The method for calculating the cutting path of an intersection line according to claim 1, characterized in that: In step 2), the line of intersection of the outer surfaces of the main pipe and the branch pipe is the outer contour line.

4. The method for calculating the cutting path of an intersection line according to claim 1, characterized in that: In step 2), the intersection line of the inner surfaces of the main pipe and the branch pipe is the inner contour line.

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