阅读说明：本技术 异种材料钎焊间隙控制方法和系统 (Dissimilar material brazing gap control method and system ) 是由 田英超 田书源 包海涛 唐兆斌 贾晶敏 许和庆 于 2021-06-23 设计创作，主要内容包括：本发明提供了一种异种材料钎焊间隙控制方法和系统,包括：根据待装配的各工件的实际结构预设装配间隙值；确定各工件的性能参数；根据各工件的钎焊结构和钎料填缝要求,确定钎焊缝位置和热结构分析的边界条件；根据热结构分析的边界条件和各工件的性能参数,分析各工件的热位移变化,并求出各工件间钎焊间隙值；根据各工件间钎焊间隙值与钎焊料的预设钎焊间隙范围进行比较和复算,获得工件间最佳的装配间隙范围；根据最佳的装配间隙范围进行工艺试验确定工件间实际装配间隙。本发明通过模拟分析将工件初始装配间隙与钎焊间隙联系起来,实现了异种材料钎焊间隙的数值化控制,保证了产品钎焊质量。(The invention provides a dissimilar material brazing gap control method and a dissimilar material brazing gap control system, which comprise the following steps: presetting an assembly clearance value according to the actual structure of each workpiece to be assembled; determining performance parameters of each workpiece; determining the position of a brazing seam and boundary conditions of thermal structure analysis according to the brazing structure of each workpiece and the brazing filler metal seam filling requirements; analyzing the thermal displacement change of each workpiece according to the boundary conditions of the thermal structure analysis and the performance parameters of each workpiece, and solving the brazing gap value between the workpieces; comparing and recalculating the brazing gap value between the workpieces with the preset brazing gap range of the brazing material to obtain the optimal assembly gap range between the workpieces; and performing a process test according to the optimal assembly clearance range to determine the actual assembly clearance between the workpieces. The invention relates the initial assembly gap and the brazing gap of the workpiece through simulation analysis, realizes numerical control of the brazing gap of dissimilar materials, and ensures the brazing quality of products.)

1. A dissimilar material brazing gap control method is characterized by comprising the following steps:

s1, drawing a three-dimensional graph of each workpiece and establishing a solid geometric model of each workpiece according to the actual structure preset assembly gap value of each workpiece to be assembled;

step S2, determining performance parameters of each workpiece according to the material of each workpiece;

step S3, determining the brazing seam position and the boundary condition of the thermal structure analysis according to the brazing structure of each workpiece and the brazing filler metal joint filling requirement;

step S4, analyzing the thermal displacement change of each workpiece according to the boundary condition of the thermal structure analysis and the performance parameters of each workpiece, and calculating the brazing gap value between the workpieces;

step S5, comparing and recalculating the brazing gap value between the workpieces with the preset brazing gap range of the brazing material to obtain the optimal assembly gap range between the workpieces;

and step S6, performing a process test according to the optimal assembly gap range, comparing the actual brazing gap with a thermal structure analysis result, optimizing boundary condition setting, determining the actual assembly gap between the workpieces, and finally controlling the brazing gap.

2. The dissimilar material brazing gap control method according to claim 1, wherein the performance parameters include density, poisson's ratio, elastic modulus, and linear expansion coefficient.

3. The dissimilar material brazing gap control method according to claim 1, wherein the boundary conditions include an initial temperature, a final temperature, and a constraint state;

wherein the initial temperature is room temperature, the final temperature is a temperature at which the brazing material is completely melted, and the constrained states include a free state, a point constrained state, and a surface constrained state.

4. The dissimilar material brazing gap control method according to claim 1, wherein thermal structure analysis software is used to analyze a thermal displacement change of each workpiece, the thermal displacement change including a displacement value and a deformation map of each workpiece.

5. The dissimilar material brazing gap control method according to claim 1, wherein extreme values of the brazing gaps of the respective workpieces at the initial temperature and the final temperature are separately found at different constraint states, and the maximum brazing gap, the minimum brazing gap and the average brazing gap are obtained based on a difference between the extreme values of the brazing gaps of the respective workpieces.

6. A dissimilar material brazing gap control system, comprising:

the module M1 is used for drawing a three-dimensional graph of each workpiece and establishing a solid geometric model of each workpiece according to the actual structure preset assembly gap value of each workpiece to be assembled;

the module M2 is used for determining the performance parameters of each workpiece according to the material of each workpiece;

the module M3 determines the brazing seam position and the boundary condition of the thermal structure analysis according to the brazing structure of each workpiece and the brazing filler metal joint filling requirement;

the module M4 analyzes the thermal displacement change of each workpiece according to the boundary condition of the thermal structure analysis and the performance parameters of each workpiece, and calculates the brazing gap value between the workpieces;

the module M5 compares and recalculates the brazing gap value between the workpieces with the preset brazing gap range of the brazing material to obtain the optimal assembly gap range between the workpieces;

and the module M6 carries out a process test according to the optimal assembly gap range, compares the actual brazing gap with the thermal structure analysis result, optimizes the setting of boundary conditions, determines the actual assembly gap between the workpieces and finally controls the brazing gap.

7. The dissimilar material brazing gap control system according to claim 6, wherein the performance parameters include density, Poisson's ratio, modulus of elasticity, and coefficient of linear expansion.

8. The dissimilar material brazing gap control system according to claim 6, wherein the boundary conditions include an initial temperature, a final temperature, and a constraint state;

wherein the initial temperature is room temperature, the final temperature is a temperature at which the brazing material is completely melted, and the constrained states include a free state, a point constrained state, and a surface constrained state.

9. A dissimilar material brazing gap control system according to claim 6, wherein thermal structure analysis software is used to analyze thermal displacement variations of each workpiece, including displacement values and deformation maps of each workpiece.

10. A dissimilar material brazing gap control system according to claim 6, wherein extreme values of the brazing gaps of the respective workpieces at the initial temperature and the final temperature are separately found at different constraint states, and the maximum brazing gap, the minimum brazing gap and the average brazing gap are obtained from difference values of the extreme values of the brazing gaps of the respective workpieces.

Technical Field

The invention relates to the technical field of brazing connection, in particular to a dissimilar material brazing gap control method and system.

Background

Brazing is a material connection method in which a base material is heated at a temperature lower than the melting point of the base material and higher than the melting point of a brazing material, and the liquid brazing material wets, spreads, fills gaps by capillary flow on the surface or in gaps of the base material, and finally solidifies and crystallizes to realize interatomic bonding.

The reasons for the lower strength of the brazing seam are as follows: the chemical reaction between the brazing material and the base material is weak, and the reaction joint surface is only between a few micrometers and dozens of micrometers. Therefore, the strength of the whole joint is required to be improved by increasing the brazing area, and the brazing area is mainly influenced by the joint filling area of the brazing material and the base material, namely the larger the brazing joint filling area is, the higher the strength of the whole joint is under the condition of constant strength per unit area; the caulking capacity is affected by capillary action, excluding material and process factors, and capillary work is dependent on the brazing gap, so controlling the brazing gap is key to improving the performance of the entire brazed joint.

The brazing gap refers to a gap at a position to be brazed of a workpiece when brazing is melted, and the gap is difficult to measure by an effective means at high temperature or the measurement cost is high, and the scheme has poor feasibility of implementation. Therefore, the assembly clearance of the workpiece needs to be preset repeatedly for brazing, and the brazing is finished through metallographic phase or other destruction means after welding, so that the production period is increased, great production waste is caused, more importantly, fuzzification of control data is caused, and the method is not beneficial to popularization and application of similar products. Therefore, an effective and quantifiable method for controlling the brazing gap of dissimilar materials is needed.

Patent document CN107649800B (application number: CN201710885788.2) discloses a lap brazing gap control device and a method for brazing by obtaining an optimum loading force. The lap brazing seam gap control device comprises a workbench, a cooling system, a brazing operation table, a first pressing device and a horizontal maintaining device. Different brazing seam gaps are obtained by controlling different loads, an optimal gap value is determined by utilizing the obtained brazing seam gaps, and then an optimal loading force corresponding to the optimal gap value is obtained; and the fixed loading is used for quantitatively controlling the brazing seam clearance in the batch production process to perform brazing, so that the brazing quality is improved.

Disclosure of Invention

In view of the defects in the prior art, the invention aims to provide a dissimilar material brazing gap control method and system.

The method for controlling the brazing gap of the dissimilar materials provided by the invention comprises the following steps:

s1, drawing a three-dimensional graph of each workpiece and establishing a solid geometric model of each workpiece according to the actual structure preset assembly gap value of each workpiece to be assembled;

step S2, determining performance parameters of each workpiece according to the material of each workpiece;

step S3, determining the brazing seam position and the boundary condition of the thermal structure analysis according to the brazing structure of each workpiece and the brazing filler metal joint filling requirement;

step S4, analyzing the thermal displacement change of each workpiece according to the boundary condition of the thermal structure analysis and the performance parameters of each workpiece, and calculating the brazing gap value between the workpieces;

step S5, comparing and recalculating the brazing gap value between the workpieces with the preset brazing gap range of the brazing material to obtain the optimal assembly gap range between the workpieces;

and step S6, performing a process test according to the optimal assembly gap range, comparing the actual brazing gap with a thermal structure analysis result, optimizing boundary condition setting, determining the actual assembly gap between the workpieces, and finally controlling the brazing gap.

Preferably, the performance parameters include density, poisson's ratio, modulus of elasticity, and coefficient of linear expansion.

Preferably, the boundary conditions include an initial temperature, a final temperature, and a constraint state;

wherein the initial temperature is room temperature, the final temperature is a temperature at which the brazing material is completely melted, and the constrained states include a free state, a point constrained state, and a surface constrained state.

Preferably, thermal structure analysis software is used to analyze thermal displacement changes of each workpiece, including displacement values and deformation maps of each workpiece.

Preferably, in different constraint states, extreme values of the brazing gaps of the workpieces at the initial temperature and the final temperature are respectively obtained, and the maximum brazing gap, the minimum brazing gap and the average brazing gap are obtained according to the difference value of the extreme values of the brazing gaps of the workpieces.

According to the dissimilar material brazing gap control system provided by the invention, the dissimilar material brazing gap control system comprises:

the module M1 is used for drawing a three-dimensional graph of each workpiece and establishing a solid geometric model of each workpiece according to the actual structure preset assembly gap value of each workpiece to be assembled;

the module M2 is used for determining the performance parameters of each workpiece according to the material of each workpiece;

the module M3 determines the brazing seam position and the boundary condition of the thermal structure analysis according to the brazing structure of each workpiece and the brazing filler metal joint filling requirement;

the module M4 analyzes the thermal displacement change of each workpiece according to the boundary condition of the thermal structure analysis and the performance parameters of each workpiece, and calculates the brazing gap value between the workpieces;

the module M5 compares and recalculates the brazing gap value between the workpieces with the preset brazing gap range of the brazing material to obtain the optimal assembly gap range between the workpieces;

and the module M6 carries out a process test according to the optimal assembly gap range, compares the actual brazing gap with the thermal structure analysis result, optimizes the setting of boundary conditions, determines the actual assembly gap between the workpieces and finally controls the brazing gap.

Preferably, the performance parameters include density, poisson's ratio, modulus of elasticity, and coefficient of linear expansion.

Preferably, the boundary conditions include an initial temperature, a final temperature, and a constraint state;

wherein the initial temperature is room temperature, the final temperature is a temperature at which the brazing material is completely melted, and the constrained states include a free state, a point constrained state, and a surface constrained state.

Preferably, thermal structure analysis software is used to analyze thermal displacement changes of each workpiece, including displacement values and deformation maps of each workpiece.

Preferably, in different constraint states, extreme values of the brazing gaps of the workpieces at the initial temperature and the final temperature are respectively obtained, and the maximum brazing gap, the minimum brazing gap and the average brazing gap are obtained according to the difference value of the extreme values of the brazing gaps of the workpieces.

Compared with the prior art, the invention has the following beneficial effects:

1. the method mainly determines the relation between the direction and the expansion of the assembly clearance of the workpiece according to the use requirements of the dissimilar welding seams, compares the expansion amounts of the dissimilar workpieces in different directions by adopting a thermal structure analysis method, performs necessary operation on the difference value of the expansion amounts and an expected value (brazing clearance recommended by brazing materials), and calculates the assembly clearance of the workpiece; and then, carrying out a process test by utilizing the assembly gap to obtain an actually measured brazing gap, comparing the actually measured brazing gap with an analysis method, optimizing boundary conditions, and obtaining the assembly gap through reverse thrust of the actual brazing gap to form a better capillary action condition, thereby ensuring the brazing quality of the product.

2. The invention solves the problems that the brazing gap of the dissimilar materials is difficult to predict and the brazing quality cannot be effectively ensured, and associates the initial assembly gap of the workpiece with the brazing gap through simulation analysis, thereby realizing numerical control of the brazing gap of the dissimilar materials and ensuring the brazing quality of products.

3. The method can save production cost, quantify brazing gap indexes, avoid repeated tests, improve the predictability of the brazing gaps of dissimilar materials and ensure the quality of welding seams.

4. The invention combines simulation analysis and a small amount of destructive tests, can greatly reduce the cost of materials, processing and tests, and has the significance of popularization and reference for similar structures or materials.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic structural diagram of a finite element model of an example workpiece;

FIG. 2 is a graph showing the change in the elastic modulus of the superalloy at different temperatures in the example;

FIG. 3 is a graph showing the change in expansion coefficient of the superalloy at different temperatures in the example;

FIG. 4 is a displacement cloud of the workpiece in the free state in the example;

FIG. 5 is a displacement cloud diagram of the workpiece in the three-point constrained state in the example.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

Example (b):

the embodiment relates to a dissimilar material brazing gap control method, for example, a tube plate structure of a certain product is taken as an example, wherein a tube is sleeved outside a plate, and brazing is in an overlapping mode, the method comprises the following steps:

step 1, presetting a common diameter assembly gap upper limit (such as a unilateral assembly gap of 0.08mm) according to actual structures of a pipe structure and a plate structure to be assembled, drawing a proe three-dimensional graph of each part, establishing a solid geometric model, and carrying out necessary simplification on the model, wherein the actual structures are shown in figure 1.

And 2, inquiring material performance parameters through a material manual aiming at the part material (the pipe structure is made of high-temperature alloy material, and the plate structure is made of stainless steel material), wherein the elastic modulus and the thermal expansion coefficient are obviously changed along with the temperature. If there is no relevant data, it can be obtained by linear extrapolation according to the existing data, as shown in fig. 2 and 3.

And 3, determining the position of the brazing seam and the heated constraint state of the workpiece according to the brazing structure of each workpiece and the brazing filler metal joint filling requirements, wherein the constraint state of the workpiece is generally divided into a free state, a point constraint state and a surface constraint state. The initial temperature (room temperature) and the final temperature (temperature at which the brazing material is completely melted) are selected as boundary conditions for subsequent thermal structure analysis.

Take a tube sheet structure (tube is made of high temperature alloy material, and plate is made of stainless steel material) as an example.

Initial temperature: 20 ℃; final temperature: 1150 ℃.

The performance parameters of the tube (material: high temperature alloy) material are as follows:

density: 8.33g/cm³(ii) a Poisson ratio: 0.35;

modulus of elasticity: 220000MPa (20 ℃), 155500MPa (1150 ℃);

coefficient of linear expansion: 1.47^-5/℃(20℃)，1.9E^-5/℃(1150℃)；

Material Performance parameters of the plate (plate: stainless Steel):

density: 7.85g/cm³(ii) a Poisson ratio: 0.3;

modulus of elasticity: 198000MPa (20 ℃), 102000MPa (1150 ℃);

coefficient of linear expansion: 1.66^-5/℃(20℃)，2.04E^-5/℃(1150℃)；

And 4, analyzing the displacement and deformation cloud pictures of each workpiece by using a thermal structure Analysis software according to the boundary conditions (including the initial temperature, the final temperature and the constraint state) and the material performance parameters, and solving the limit values of the brazing parts of each part at the initial temperature and the final temperature, wherein the maximum brazing gap, the minimum brazing gap and the average brazing gap are obtained according to the limit difference value of the brazing parts of each part, as shown in fig. 4 and 5, fig. 4 is a deformation cloud picture of each part of the workpiece in a free state, and fig. 5 is a deformation cloud picture of each part of the workpiece in a three-point constraint state.

Take the free state as an example (considering the limit state at the time of assembly):

initial average fit clearance: 0.08 mm; maximum brazing gap: 0.1119 mm; minimum brazing gap: 0 mm; average brazing gap: 0.0119 mm.

Take three-point constraint as an example (considering uniform positioning constraint during assembly):

initial assembly clearance: 0.08 mm; maximum brazing gap: 0.08mm (at the constraint point); minimum brazing gap: 0.005 mm; average brazing gap: 0.0319 mm.

Step 5, in the actual brazing production process, the workpiece is usually restrained and positioned, so that only the restraint state is considered in the implementation. Assembly gap (which means the gap and half in the diameter direction between the parts before welding and heating), brazing gap (which means the gap and half in the diameter direction between the parts when welding and heating to a predetermined temperature), average brazing gap (which means the gap and half in the diameter direction between the parts on the entire arc surface when welding and heating to a predetermined temperature). The reference recommended braze gap range of 0.03-0.07mm, based on an average braze gap of 0.0319mm, which is about 0.05mm smaller than the initial fit gap, is near the lower limit, thus increasing the initial fit gap from 0.08mm to 0.1 mm. The recalculation results are as follows:

initial assembly clearance: 0.1 mm; maximum brazing gap: 0.1mm (at the constraint point); minimum brazing gap: 0.025 mm; average brazing gap: 0.0519 mm.

Considering that the average brazing gap is near the median of the recommended brazing gap, the minimum brazing gap is 0.025 and is close to 0.03mm, and the requirement of brazing material wetting and filling can be met. The brazing gap at the constraint points is 0.10mm at the maximum, but is limited to the constraint points, and the gap variation is continuous and can be disregarded. Therefore, the assembly clearance of the brazing part of the structural workpiece is controlled to be about 0.1mm, and the assembly clearance is determined to be in the range of (0.1-X) - (0.1+ Y) according to the part machining difficulty, wherein (X, Y is the machining tolerance of the brazing matching parts of the two workpieces to be welded respectively) is determined according to the material and the structure of the tube plate part to distribute the machining tolerance of the brazing matching parts of the parts.

And 6, obtaining the optimal assembly gap range according to analysis, designing and processing the simplified workpiece, carrying out multi-point sectioning on the welded seam after brazing, determining the average brazing gap through welding seam observation, comparing with a thermal analysis result, optimizing boundary condition setting, and determining the actual assembly gap of the workpiece. Specifically, after brazing, 6-point sectioning is carried out on a welding line along the center, observation is carried out through a body type microscope and the like, a brazing gap is actually measured, the actually measured result is compared with structural thermal analysis data, and an initial assembly gap is adjusted.

In order to effectively control the brazing gap and ensure the quality of the welding seam, the invention provides the dissimilar material brazing gap control method, which can save the production cost, quantify the brazing gap index, avoid repeated tests, improve the predictability of the dissimilar material brazing gap and ensure the quality of the welding seam.

Aiming at the characteristics and the use requirements of the brazing structure, the invention obtains brazing gap data through simulation analysis, compares the brazing gap data with the recommended gap of the brazing material, calculates the assembly gap of the workpiece, determines the optimal assembly gap through test verification and analysis methods, and finally controls the assembly gap of the workpiece.

Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.