Simulation calculation determination method for size of prefabricated hole in hole drawing process

Abstract

The invention relates to the technical field of machining and manufacturing, in particular to a simulation calculation and determination method for the size of a prefabricated hole in a hole drawing process, which comprises a modeling stage, a calculation stage and a determination stage. And a modeling stage: according to the preset sizes of the actual main pipe and the target branch pipe, establishing geometric models of the simulation main pipe and the simulation branch pipe, setting the thermal expansion coefficient of the simulation branch pipe as a negative value, and setting a thermal boundary condition for the simulation branch pipe to input heat to the simulation branch pipe. In the calculation stage, the simulation branch pipes are heated to shrink towards the roots of the simulation branch pipes to form through holes in the simulation main pipe. In the determining stage, the size of the through hole is obtained and serves as the size of the prefabricated hole formed in the actual main pipe in the hole pulling test. According to the simulation calculation determination method for the size of the prefabricated hole in the hole drawing process, a reverse design thought is adopted, the simulation branch pipe is reversely shrunk to finally obtain the predicted size of the prefabricated hole, and a test is performed according to the predicted size, so that the cost can be reduced, and the efficiency can be improved.

Description

Technical Field

[0001] This invention relates to the field of machining and manufacturing technology, and in particular to a method for simulation calculation and determination of pre-made hole size in a hole-drawing process. Background Technology

[0002] The T-Pull process is a pre-forming method for butt welding pipe fittings. When a branch pipe needs to be welded to the side wall of a main pipe, the T-Pull process involves first creating a pre-drilled hole in the side wall of the main pipe, then pulling the branch pipe outward from the pre-drilled hole, and finally butt welding the branch pipe to the branch pipe. The T-Pull process effectively reduces the difficulty of pipe welding and avoids the disadvantages of traditional pipe welding methods, such as stress concentration and poor stability. The size of the branch pipe is estimated based on the size of the branch pipe, and then the size of the pre-drilled hole in the side wall of the main pipe is estimated based on the sizes of the main pipe and the branch pipe. An inappropriate pre-drilled hole size can cause cracking or uneven end faces in the formed branch pipe, directly affecting the butt welding quality between the branch pipe and the branch pipe. Currently, the size of the pre-drilled hole is mainly determined by process experiments and experience, which is not only costly but also inefficient. Summary of the Invention

[0003] The purpose of this invention is to provide a simulation calculation method for determining the size of pre-fabricated holes in a hole-drawing process, which can reduce experimental costs and improve experimental efficiency.

[0004] To achieve this objective, the present invention adopts the following technical solution: A simulation calculation method is provided to determine the pre-drilled hole size in a hole-drawing process, including: Modeling stage: Based on the preset dimensions of the actual main pipe and the target branch pipe, establish the geometric models of the simulated main pipe and simulated branch pipe, set the thermal expansion coefficient of the simulated branch pipe to a negative value, and set thermal boundary conditions for the simulated branch pipe to input heat into the simulated branch pipe; Calculation phase: The simulated branch pipe is configured to contract towards its own root when heated, forming a through hole on the simulated main pipe; Determination stage: Obtain the size of the through hole as the size of the pre-fabricated hole to be opened on the actual main pipe in the hole-pulling test.

[0005] Optionally, the modeling stage further includes: setting pressure boundary conditions for the simulated pipe, and applying a pressure load F1 to the simulated pipe in the later stage of the simulated pipe being heated; The calculation phase further includes: the simulated branch pipe is configured to be subjected to the pressure load F1 in the later stage of heating, so that the simulated branch pipe is compressed to be completely on the same curved surface as the sidewall of the simulated main pipe, forming the through hole.

[0006] Optionally, the modeling stage further includes: establishing a geometric model of the simulated tube, wherein the simulated tube is a rigid tube, the simulated tube is coaxially inserted into the simulated main tube, and the simulated tube contacts the inner wall of the simulated main tube to prevent the simulated main tube from deforming inward.

[0007] Optionally, the modeling stage further includes: applying a pressure load F2 to the outer wall of the simulated main pipe to prevent the simulated main pipe from bulging outward when the simulated branch pipe contracts or is compressed.

[0008] Optionally, the temperature constraint of the analog tube is a reference temperature T1, so that the temperature of the analog tube is limited within a preset range.

[0009] Optionally, the thermal boundary condition set for the simulated branch pipe is to input heat at the edge of the simulated branch pipe away from the simulated main pipe.

[0010] Optionally, the heat input to the simulated distribution pipe gradually increases as the simulation calculation proceeds.

[0011] Optionally, the modeling stage further includes setting the mechanical properties of the simulation main tube and the simulation branch tube.

[0012] Optionally, the mechanical properties of the simulated main pipe and the simulated branch pipe are set to be consistent.

[0013] Optionally, the thermodynamic properties of the simulated main pipe and the simulated branch pipe are set to be consistent.

[0014] The beneficial effects of this invention are: This invention provides a simulation calculation method for determining the pre-drilled hole size in a hole-pulling process, comprising a modeling stage, a calculation stage, and a determination stage. In the modeling stage: based on the preset dimensions of the actual main pipe and the target branch pipe, geometric models of the simulated main pipe and simulated branch pipe are established. The thermal expansion coefficient of the simulated branch pipe is set to a negative value, and thermal boundary conditions are set for the simulated branch pipe to input heat. In the calculation stage: the simulated branch pipe is configured to contract towards its root upon heating, forming a through hole on the simulated main pipe. In the determination stage: the size of the through hole is obtained as the size of the pre-drilled hole to be opened on the actual main pipe in the hole-pulling test. This simulation calculation method for determining the pre-drilled hole size in a hole-pulling process adopts a reverse design approach, obtaining the predicted size of the pre-drilled hole by reverse contraction of the simulated branch pipe. Using the predicted size as the size of the pre-drilled hole in the main pipe in the hole-pulling test reduces the number of tests, thereby reducing costs and obtaining the final pre-drilled hole size more quickly, thus improving efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the model at the start of the calculation phase provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the model simulating the contraction of the branch section during the calculation stage provided in the embodiment of the present invention; Figure 3 This is a schematic diagram of a model simulating further contraction of the branch tube but without force during the calculation stage provided in this embodiment of the invention; Figure 4 This is a schematic diagram of the model after simulating the force on each pipe in the calculation stage provided in the embodiment of the present invention.

[0016] In the picture: 1. Simulated main pipe; 11. Through hole; 2. Simulated branch pipe; 21. Edge; 3. Simulated pipe. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings, not all of them.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0019] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0020] The T-Pull process is a pre-forming method for butt welding pipe fittings. When a branch pipe needs to be welded to the side wall of a main pipe, the T-Pull process involves first creating a pre-drilled hole in the side wall of the main pipe, then pulling the branch pipe outward from the pre-drilled hole, and finally butt welding the branch pipe to the branch pipe. The T-Pull process effectively reduces the difficulty of pipe welding and avoids the disadvantages of traditional pipe welding methods, such as stress concentration and poor stability. The size of the branch pipe is estimated based on the size of the branch pipe, and then the size of the pre-drilled hole in the side wall of the main pipe is estimated based on the sizes of the main pipe and the branch pipe. An inappropriate pre-drilled hole size can cause cracking or uneven end faces in the formed branch pipe, directly affecting the butt welding quality between the branch pipe and the branch pipe. Currently, the size of the pre-drilled hole is mainly determined by process experiments and experience, which is not only costly but also inefficient.

[0021] Therefore, this embodiment provides a simulation calculation method for determining the pre-drilled hole size in the hole-drawing process to solve the above problems. This simulation calculation method for determining the pre-drilled hole size in the hole-drawing process can reduce experimental costs and improve experimental efficiency.

[0022] like Figure 1 As shown, the simulation calculation method for determining the pre-drilled hole size in the hole-pulling process of this embodiment includes a modeling stage, a calculation stage, and a determination stage. In the modeling stage: based on the preset dimensions of the actual main pipe and the target branch pipe, geometric models of the simulated main pipe 1 and simulated branch pipe 2 are established. The thermal expansion coefficient of the simulated branch pipe 2 is set to a negative value, and thermal boundary conditions are set for the simulated branch pipe 2 to input heat. In the calculation stage: the simulated branch pipe 2 is configured to contract towards its root upon heating, forming a through hole 11 on the simulated main pipe 1. In the determination stage: the size of the through hole 11 is obtained as the size of the pre-drilled hole to be opened on the actual main pipe in the hole-pulling test.

[0023] The simulation calculation method for determining the pre-drilled hole size in this hole-pulling process adopts a reverse design approach. That is, the thermal expansion coefficient of the simulated branch pipe 2 is set to a negative value, and heat is input into the simulated branch pipe 2 to cause it to shrink under heat and form a through hole 11 on the main pipe. The size of the through hole 11 can be used as the predicted size of the pre-drilled hole. Using this predicted size as the size of the pre-drilled hole in the main pipe during the hole-pulling test can reduce the number of tests, thereby reducing costs and obtaining the final pre-drilled hole size more quickly, thus improving efficiency.

[0024] The dimensions of the target branch pipe are generally related to those of the branch pipe and can be selected based on the actual needs of butt welding between the branch pipe and the branch pipe. Furthermore, it should be understood that the dimensions mentioned in this embodiment include shape, size, thickness, etc.

[0025] Since the simulated manifold 2 will still have slight protrusions during the later stages of thermal contraction, to speed up the process and completely smooth out these protrusions, the modeling stage may optionally include setting pressure boundary conditions for the simulated manifold 2, applying a pressure load F1 to the simulated manifold 2 during the later stages of heating. Correspondingly, the calculation stage also includes configuring the simulated manifold 2 to be subjected to the pressure load F1 during the later stages of heating, so that the simulated manifold 2 is compressed to be completely flush with the sidewall of the simulated main pipe 1, thus forming a through-hole 11 on the simulated main pipe 1.

[0026] Therefore, the simulation calculation method for determining the pre-drilled hole size in this hole-pulling process first inputs heat into the simulated branch pipe 2, causing it to begin shrinking, such as... Figure 2 As shown. Figure 3 As shown, during the later stage of heating of simulated pipe 2, it is flattened and shaped to make simulated pipe 2 as shown. Figure 4 When fully contracted, the simulated main pipe 1 is on the same curved surface as the sidewall of the simulated main pipe 1, thus obtaining an elliptical through hole 11 on the simulated main pipe 1, and thus obtaining the predicted size of the pre-made hole.

[0027] To prevent the simulated main pipe 1 from being stressed during the heating or contraction of the simulated branch pipe 2, the modeling stage may optionally include establishing a geometric model of the simulated pipe 3. The simulated pipe 3 is a rigid pipe, coaxially inserted into the simulated main pipe 1, and in contact with the inner wall of the simulated main pipe 1. When the simulated branch pipe 2 is heated or stressed, the simulated pipe 3 can support the simulated main pipe 1 to prevent the simulated main pipe 1 from deforming inward.

[0028] Optionally, the modeling stage also includes applying a pressure load F2 to the outer wall of the simulated main pipe 1 to prevent the simulated branch pipe 2 from bulging outwards when it contracts or is under pressure. During the contraction of the simulated branch pipe 2, there may be material accumulation at the root of the simulated branch pipe 2, and the simulated main pipe 1 connected to it is at risk of bulging outwards. Therefore, by applying a pressure load F2 to the outer wall of the simulated main pipe 1, the bulging outwards of the simulated main pipe 1 can be prevented, ensuring that the final shape of the simulated main pipe 1 is a normal tubular shape, which is consistent with the shape of the actual main pipe in the hole-pulling process.

[0029] Optionally, the temperature constraint of the simulation tube 3 is the reference temperature T1, which ensures that during the calculation phase, the simulation tube 3 can continuously absorb a large amount of heat transferred from the simulation branch tube 2 to the simulation main tube 1, so that the temperature of the simulation main tube 1 is limited within a preset range and the temperature of the simulation branch tube 2 will not increase significantly.

[0030] It can be seen that the simulation tube 3 has multiple functions. It can not only support the simulation main tube 1 and prevent the simulation main tube 1 from being concave and deformed, but also assist the simulation branch tube 2 in being flattened and shaped. In addition, it can ensure that the temperature of the simulation main tube 1 and the simulation branch tube 2 are within the preset range, ensuring that the calculation is carried out normally.

[0031] Optionally, the thermal boundary condition set for the simulated branch pipe 2 is to input heat at the edge 21 of the simulated branch pipe 2 away from the simulated main pipe 1, and then conduct the heat through the simulated branch pipe 2 so that the lower part of the simulated branch pipe 2 also gradually contracts.

[0032] Optionally, the heat input to the simulated pipe 2 gradually increases as the simulation calculation progresses, so that the simulated pipe 2 can continuously contract. Specifically, if the temperature at the edge 21 of the simulated pipe 2 is kept constant or the heat input efficiency is kept constant, a heat transfer equilibrium will eventually be reached. The temperature from the high temperature at the edge 21 of the simulated pipe 2 to the temperature of the area in contact with the simulated pipe 3 of the isothermal body will reach equilibrium, at which point the contraction of the simulated pipe 2 will stop. Therefore, in order for the simulated pipe 2 to contract fully, it is necessary to further increase the temperature at the edge 21 of the simulated pipe 2 or increase the heat input so that the simulated pipe 2 can continue to contract.

[0033] Optionally, the modeling stage also includes setting the mechanical properties of the simulated main pipe 1 and simulated branch pipe 2. The parameters of the mechanical properties include Poisson's ratio, yield strength, sculpted strength (or stress-strain curve), elastic modulus, and mass density.

[0034] Optionally, the mechanical properties of the simulated main pipe 1 and the simulated branch pipe 2 are set to be consistent. During the contraction process, the simulated branch pipe 2 maintains a stress-strain balance with the simulated main pipe 1. If the mechanical properties of the simulated main pipe 1 and the simulated branch pipe 2 are inconsistent, the through-hole shapes formed by them will be inconsistent.

[0035] Optionally, the thermodynamic properties of the simulated main pipe 1 and the simulated branch pipe 2 are set to be consistent. Thermodynamic property parameters include coefficient of thermal expansion, specific heat capacity, and thermal conductivity. The coefficients of thermal expansion for both simulated main pipe 1 and simulated branch pipe 2 are negative. It should be noted that the values ​​of the thermodynamic property parameters used in the modeling are not related to the actual material constitutive model. Based on the input heat value, under the aforementioned thermodynamic material constitutive model, the simulated branch pipe 2 should generate a sufficiently large "shrinkage deformation." Only with a sufficiently large shrinkage deformation can the simulated branch pipe 2 gradually approach a flat state. Setting the coefficient of thermal expansion of the simulated main pipe 1 to a negative value allows for slight shrinkage near the simulated branch pipe 2, closely resembling the process of material thinning during the hole-pulling process.

[0036] Optionally, the simulation calculation method for determining the pre-drilled hole size in this hole-drawing process can be performed using MSC.Marc finite element simulation software. The geometric models of the simulated main pipe 1 and simulated branch pipe 2 are consistent with the preset dimensions of the actual main pipe and target branch pipe, such as... Figure 1 As shown, no significant shrinkage of simulated branch pipe 2 was observed at the beginning of the calculation phase. Figure 2As shown, after the calculation has been running for a period of time, the simulated branch pipe 2 shows a significant contraction. Figure 3 As shown, after the calculation continued for a period of time, the simulated branch pipe 2 shrank to almost flush with the wall of the simulated main pipe 1. Figure 4 As shown, under the combined effects of thermal contraction and pressure from the outside in, the simulated branch pipe 2 becomes completely flush with the wall of the simulated main pipe 1, forming an elliptical through hole. By measuring this through hole, the size of the pre-fabricated hole opened on the actual main pipe in the hole-pulling test can be obtained.

[0037] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for determining the size of pre-fabricated holes in a hole-drawing process through simulation calculation, characterized in that, include: Modeling stage: According to the preset dimensions of the actual main pipe and the target branch pipe, establish the geometric model of the simulated main pipe (1) and the simulated branch pipe (2), set the thermal expansion coefficient of the simulated branch pipe (2) to a negative value, and set the thermal boundary conditions for the simulated branch pipe (2) to input heat into the simulated branch pipe (2); Calculation phase: The simulated branch pipe (2) is configured to shrink towards its own root when heated, forming a through hole (11) on the simulated main pipe (1). Determination stage: Obtain the size of the through hole (11) as the size of the pre-fabricated hole opened on the actual main pipe in the hole-pulling test.

2. The method for determining the pre-fabricated hole size in the hole-drawing process according to claim 1, characterized in that, The modeling stage also includes: setting the pressure boundary conditions of the simulated pipe (2), and applying a pressure load F1 to the simulated pipe (2) in the later stage of the simulated pipe (2) being heated; The calculation phase further includes: the simulated branch pipe (2) is configured to be subjected to the pressure load F1 in the later stage of heating, so that the simulated branch pipe (2) is compressed to be completely on the same curved surface as the sidewall of the simulated main pipe (1), forming the through hole (11).

3. The method for determining the pre-drilled hole size in the hole-drawing process according to claim 2, characterized in that, The modeling stage also includes: establishing a geometric model of the simulated tube (3), wherein the simulated tube (3) is a rigid tube, the simulated tube (3) is coaxially inserted into the simulated main tube (1), and the simulated tube (3) contacts the inner wall of the simulated main tube (1) to prevent the simulated main tube (1) from being concave and deformed.

4. The method for determining the pre-drilled hole size in the hole-drawing process according to claim 3, characterized in that, The modeling stage also includes applying a pressure load F2 to the outer wall of the simulated main pipe (1) to prevent the simulated main pipe (1) from bulging outward when the simulated branch pipe (2) contracts or is compressed.

5. The method for determining the pre-drilled hole size in the hole-drawing process according to claim 3, characterized in that, The temperature constraint of the analog tube (3) is the reference temperature T1, so that the temperature of the analog tube (1) is limited within a preset range.

6. The method for determining the size of pre-fabricated holes in the hole-drawing process according to any one of claims 1-5, characterized in that, The thermal boundary condition set for the simulated branch pipe (2) is to input heat at the edge (21) of the simulated branch pipe (2) away from the simulated main pipe (1).

7. The method for determining the size of pre-fabricated holes in the hole-drawing process according to any one of claims 1-5, characterized in that, The heat input to the simulated pipe (2) gradually increases as the simulation calculation proceeds.

8. The method for determining the pre-fabricated hole size in the hole-drawing process according to any one of claims 1-5, characterized in that, The modeling stage also includes setting the mechanical properties of the simulation main tube (1) and the simulation branch tube (2).

9. The method for determining the size of pre-fabricated holes in the hole-drawing process according to claim 8, characterized in that, The mechanical properties of the simulated main tube (1) and the simulated branch tube (2) are set to be consistent.

10. The method for determining the pre-fabricated hole size in the hole-drawing process according to any one of claims 1-5, characterized in that, The thermodynamic properties of the simulated main pipe (1) and the simulated branch pipe (2) are set to be consistent.

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