Assembly tolerance analysis method and device for structural part and medium

Abstract

The invention discloses an assembly tolerance analysis method and device of a structural part and a medium, and relates to the technical field of assembly, a three-dimensional model library of the structural part is obtained, a reference part and a to-be-assembled part are determined from the three-dimensional model library, and an assembly model of the reference part and the to-be-assembled part is constructed; adding a deviation range of a deviation item to the assembly model, and establishing a measurement item of the assembly model; performing simulation assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result; determining target measurement items which do not conform to the standard and contribution degrees of the deviation items to the target measurement items according to a tolerance analysis result; the target deviation range of the target deviation item with the contribution degree larger than the preset value is adjusted so that the target measurement item can meet the standard, and the adjusted deviation range serves as the standard of structural part manufacturing and assembling, so that deviation in the actual assembling process can be reduced, and repair caused by deviation after structural part assembling is completed is reduced.

Description

Technical Field

[0001] The present application relates to the field of assembly technology, and in particular to an assembly tolerance analysis method, device and medium for structural parts. Background Art

[0002] With the continuous development of high-speed and heavy-load rail transit vehicles in my country, it is particularly important to improve the energy efficiency of rail vehicles. The high-speed train requires the provision of locomotive traction power on the one hand, and the lightweight of the train on the other hand. The application of new materials is the most important and effective way to lightweight. Composite materials have the material properties of high specific strength, high specific stiffness, corrosion resistance, fatigue resistance, and impact resistance. Composite body design has become the mainstream. With the application of new materials in vehicle sound, new requirements are also put forward for vehicle assembly technology. Due to the accumulation of deviations caused by the processing errors of the structural parts themselves and environmental factors such as temperature and gravity, the transmission of deviation flow during the assembly process, and the possible deformation of the material itself, there are inevitable factors such as loose fitting and inconsistent gaps between parts, which leads to poor structural riveting performance.

[0003] In the existing vehicle body assembly process, the deviation is generally handled by on-site repair, which mainly involves adjusting various deviations in the assembly process by means of tooling compression, adding gaskets, removing materials, etc. The repair process is time-consuming, labor-intensive and costly.

[0004] How to reduce the occurrence of deviations during the actual assembly process and reduce the rework of structural parts due to deviations after assembly is a problem that technical personnel in this field need to solve. Summary of the invention

[0005] The purpose of the present application is to provide a method, device and medium for analyzing the assembly tolerance of a structural part, which are used to solve the problem of requiring rework when deviations occur during the assembly of a vehicle body.

[0006] In order to solve the above technical problems, the present application provides a method for analyzing the assembly tolerance of a structural part, comprising:

[0007] Acquire a three-dimensional model library of structural parts, determine reference parts and parts to be assembled from the three-dimensional model library, and construct assembly models of the reference parts and parts to be assembled;

[0008] adding a deviation range of a deviation item to the assembly model, and establishing a measurement item of the assembly model;

[0009] Performing simulation assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result;

[0010] Determine the target measurement item that does not meet the standard and the contribution of each deviation item to the target measurement item according to the tolerance analysis result;

[0011] Determine a target deviation item whose contribution is greater than a preset value, adjust a target deviation range corresponding to the target deviation item, and output the adjusted deviation range of the target deviation item after the target measurement item meets the standard.

[0012] In a feasible embodiment, the step of constructing the assembly model of the reference part and the part to be assembled includes:

[0013] Determining a first characteristic surface of the reference part and a second characteristic surface of the part to be assembled according to the mating surfaces involved in the assembly of the reference part and the part to be assembled;

[0014] respectively setting three first positioning points on the first characteristic surface and three second positioning points on the second characteristic surface;

[0015] Based on the 3-2-1 positioning reference, the six degrees of freedom of the part to be assembled relative to the reference part are constrained; wherein three degrees of freedom of the part to be assembled are controlled by the X direction of three second positioning points, two degrees of freedom of the part to be assembled are controlled by the Y direction of two second positioning points, and one degree of freedom of the part to be assembled is controlled by the Z direction of one second positioning point;

[0016] The three first positioning points are set as target points, the three second positioning points are set as object points, and each object point is simulated and moved to each target point to construct the assembly model.

[0017] In a feasible embodiment, after adjusting the target deviation range corresponding to the target deviation item, the method further includes:

[0018] After the target deviation range is narrowed to the preset deviation range, if the target measurement item still does not meet the standard, adjusting the assembly method of the assembly model until the target measurement item meets the standard;

[0019] The preset deviation range is a minimum deviation range limited by manufacturing and assembly accuracy.

[0020] In a feasible embodiment, the deviation range of adding the deviation item to the assembly model includes:

[0021] Acquire the assembly process file, obtain the deviation items related to each structural part and the deviation values ​​corresponding to each deviation item;

[0022] The target positioning point and / or target feature surface involved in the deviation item is determined, and the deviation range of the target feature point and / or the target feature surface is added according to the deviation value corresponding to the deviation item.

[0023] In a feasible embodiment, the measurement items for establishing the assembly model include:

[0024] Determine the type of the measurement item; wherein the type of the measurement item includes a point-to-point measurement item, a point-to-plane measurement item, and a plane-to-plane measurement item;

[0025] According to the type of the measurement item, measurement points and / or measurement surfaces are added to the reference part and the part to be assembled corresponding to the assembly model, and the error tolerance range is set for each measurement item according to the product inspection requirements.

[0026] In a feasible embodiment, the adjusting the assembly mode of the assembly model includes:

[0027] determining a target axis that has the greatest impact on the stability of the assembly model;

[0028] Determine a first set of positioning points for controlling the rotation of the part to be assembled relative to the reference part around the target axis;

[0029] A second group of positioning points of the assembly model involved in the target measurement item is determined, and a position of each positioning point in the second group of positioning points is adjusted to reduce a distance between each positioning point in the second group of positioning points and a plane where the first group of positioning points are located.

[0030] In a feasible embodiment, performing simulation assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain the tolerance analysis result includes:

[0031] Changing the deviation item under the condition that each deviation item satisfies the corresponding deviation range;

[0032] Performing simulated assembly calculation on the assembly model after each change of the deviation item according to the measurement item;

[0033] The tolerance analysis result is obtained by performing statistical analysis on multiple simulated assembly calculation results.

[0034] The present application also provides a structural component assembly tolerance analysis device, comprising:

[0035] A construction module is used to obtain a three-dimensional model library of structural parts, determine reference parts and parts to be assembled from the three-dimensional model library, and construct assembly models of the reference parts and parts to be assembled;

[0036] An adding module, used for adding a deviation range of a deviation item to the assembly model and establishing a measurement item of the assembly model;

[0037] A simulated assembly calculation module, used for performing simulated assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result;

[0038] A determination module, used to determine the target measurement item that does not meet the standard and the contribution of each deviation item to the target measurement item according to the tolerance analysis result;

[0039] The deviation range adjustment module is used to determine the target deviation item whose contribution is greater than a preset value, adjust the target deviation range corresponding to the target deviation item, and output the deviation range after the target measurement item meets the standard.

[0040] The present application also provides an assembly tolerance analysis device for a structural part, comprising a memory for storing a computer program;

[0041] A processor is used to implement the steps of the assembly tolerance analysis method of the structural parts when executing the computer program.

[0042] The present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the assembly tolerance analysis method of a structural component are implemented.

[0043] The present application provides an assembly tolerance analysis method for a structural part, including: obtaining a three-dimensional model library of the structural part, determining a reference part and a part to be assembled from the three-dimensional model library, and constructing an assembly model of the reference part and the part to be assembled; adding a deviation range of a deviation item to the assembly model, and establishing a measurement item of the assembly model; performing a simulated assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result; determining a target measurement item that does not meet the standard and a contribution of each deviation item to the target measurement item according to the tolerance analysis result; determining a target deviation item whose contribution is greater than a preset value, adjusting a target deviation range corresponding to the target deviation item, and outputting the adjusted deviation range of the target deviation item after the target measurement item meets the standard. The assembly model is obtained by simulating the assembly of the structural part, and the tolerance analysis result is obtained by simulating the assembly of the assembly model, and the target measurement item that does not meet the standard and the target deviation item that has a greater impact on the target measurement item are determined according to the tolerance analysis result, and the target deviation range of the target deviation item is adjusted to make the target measurement item meet the standard, and the adjusted deviation range is used as the standard for manufacturing and assembling the structural part, so as to reduce the generation of deviations in the actual assembly process and reduce the rework of the structural part due to deviations after the assembly is completed. In addition, adjusting the target deviation range corresponding to the target deviation item that has a greater impact on the target measurement item, rather than blindly adjusting the deviation range of all deviation items, can reduce unnecessary adjustments and improve overall work efficiency. It also avoids the risk of introducing new problems by adjusting the deviation range of deviation items with smaller impacts.

[0044] The beneficial effects of the assembly tolerance analysis device and medium of the structural parts provided in the present application correspond to the method, and the effects are as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 A flowchart of a method for analyzing assembly tolerance of a structural component provided in an embodiment of the present application;

[0047] Figure 2 A schematic diagram of a base frame and end wall assembly provided in an embodiment of the present application;

[0048] Figure 3 A first schematic diagram of a positioning point of an end wall component provided in an embodiment of the present application;

[0049] Figure 4 A second schematic diagram of a positioning point of an end wall component provided in an embodiment of the present application;

[0050] Figure 5 A schematic diagram of a positioning point constraint degree of freedom provided in an embodiment of the present application;

[0051] Figure 6 A schematic diagram of a base frame component positioning point provided in an embodiment of the present application;

[0052] Figure 7 A structural diagram of an assembly tolerance analysis device for a structural part provided in an embodiment of the present application;

[0053] Figure 8 A structural diagram of another structural component assembly tolerance analysis device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] The core of this application is to provide a method, device and medium for analyzing the assembly tolerance of structural parts, which are used to reduce the generation of deviations in the actual assembly process and reduce the rework of structural parts due to deviations after assembly.

[0056] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0057] Figure 1 A flowchart of a method for analyzing assembly tolerance of a structural component provided in an embodiment of the present application is shown in FIG. Figure 1 As shown in the figure, the assembly tolerance analysis method of structural parts includes:

[0058] S10: Acquire a three-dimensional model library of the structural parts, determine the reference parts and the parts to be assembled from the three-dimensional model library, and construct an assembly model of the reference parts and the parts to be assembled.

[0059] Taking the car body as an example, the structural parts of the car body include the roof, side walls, end walls and chassis, etc. The 3D models of these structural parts are imported into the tolerance analysis software. Taking the end wall assembly process in the whole vehicle assembly process as an example, the chassis can be used as the reference part and the end wall as the part to be assembled. Of course, there is no specific limit on the number of reference parts and parts to be assembled.

[0060] Regarding how to construct the assembly model of the reference part and the part to be assembled, the assembly features of the reference part and the part to be assembled can be determined respectively, and the assembly model is constructed based on the assembly features. Assembly features include feature faces and feature points, etc. Feature faces are established on the mating surfaces of each part (reference part and part to be assembled), positioning points are selected on the feature faces according to the assembly process, and the positioning points are set as feature points. The positioning points of the reference part are set as target points, and the positioning points on the part to be assembled are set as object points. Assembly is achieved by corresponding each object point to each target point, thereby constructing the assembly model of the reference part and the part to be assembled.

[0061] S11: Add a deviation range of the deviation item to the assembly model, and establish a measurement item of the assembly model.

[0062] Deviation items include manufacturing deviation and assembly deviation. Manufacturing deviation refers to the error of a part before assembly occurs, such as the contour of the part surface and the size of the part itself (length, thickness, etc.); assembly deviation refers to the error introduced by the part during the assembly process, such as the offset of the positioning point and the floating of the hole axis of the upper and lower assembly holes. For manufacturing deviation, it is generally added directly on the feature surface of the part. Taking the contour as an example, the contour adding scheme for a certain part is: select the surface to be assembled of the part, add the contour deviation item and the deviation range corresponding to the contour deviation on the established feature surface. For assembly deviation, taking the hole position deviation as an example, it is generally added by adding the circular deviation of the XY plane and the deviation range corresponding to the circular deviation to the assembly feature point. This set of circular deviations reflects the fluctuation of the hole within a range in the XY plane.

[0063] After completing the deviation definition, according to the product inspection items marked in the assembly process file, select reasonable measurement points or measurement surfaces on each part (reference parts and parts to be assembled) to create measurement items, that is, establish measurement items on the assembly model. According to the measurement items marked in the process file, they are divided into: point-to-point measurement items, point-to-surface measurement items, and surface-to-surface measurement items. According to the type of measurement items, add a group of measurement points or measurement surfaces on the parts (reference parts and parts to be assembled) corresponding to the assembly model, and set the error tolerance range for each measurement item according to the product inspection requirements.

[0064] S12: Performing simulation assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result.

[0065] After the assembly features, deviation items, and measurement items are added, the assembly model is simulated and calculated 10,000 times based on the Monte Carlo method. The deviation items are changed when all deviation items meet their corresponding deviation ranges. The assembly model is simulated and calculated after each deviation item is changed according to the measurement items. The tolerance analysis results are obtained by statistically analyzing the results of multiple simulated assembly calculations. Each simulated assembly calculation randomly changes any one or more deviation items, but the changed deviation items need to meet their corresponding deviation ranges. For example, the deviation range of the flatness of the bottom surface of the end wall is ≤2mm. No matter how the flatness of the bottom surface of the end wall is changed, its deviation from the standard data needs to be less than or equal to 2mm.

[0066] The calculation results of each simulated assembly include measurement items that do not meet the requirements. How to determine whether a measurement item does not meet the requirements? Specifically: after the simulated assembly is completed, the measurement data of each measurement item can be detected, and the deviation of the measurement item can be obtained based on the measurement data and the standard data of the measurement item. If the deviation is within the allowable error range of the measurement item, the measurement item meets the requirements. If the deviation is not within the allowable error range of the measurement item, the measurement item does not meet the requirements.

[0067] S13: Determine the target measurement items that do not meet the standards and the contribution of each deviation item to the target measurement item according to the tolerance analysis results.

[0068] Each simulation assembly calculation result can determine the measurement items that do not meet the requirements. According to the simulation assembly calculation results, the number of times each measurement item does not meet the requirements is counted, and then the deviation rate of each measurement item is determined. According to the deviation rate, the target measurement items that do not meet the standards are determined. If a measurement item does not meet the requirements 5000 times in 10000 simulation assembly calculation results, the deviation rate of the measurement item is 5000 / 10000=50%. If the deviation rate is set to exceed 20% as non-compliant, then the measurement item is determined as a target measurement item that does not meet the standards.

[0069] How to determine the contribution of each deviation item to the target measurement item can be determined based on the Monte Carlo method. Specifically: (1) Define the problem and variables: First, it is necessary to clarify the target measurement item and the various deviation items that may affect the target measurement item. (2) Build a model: Construct a mathematical model to describe the relationship between the target measurement item and the deviation item. This model should be able to capture the impact mechanism of each deviation item on the target measurement item. (3) Generate random samples: Generate a large number of random samples for each deviation item. The deviation items corresponding to the samples need to meet their respective deviation ranges. (4) Simulate and calculate: For each group of randomly generated deviation item samples, use the established model to calculate the value of the target measurement item, so that a group of simulated target measurement item values ​​will be obtained. (5) Statistical analysis: Perform statistical analysis on the simulated target measurement item values ​​to determine the contribution of each deviation item to the target measurement item. This can be achieved by calculating the change range, variance or standard deviation of the target measurement item value when each deviation item changes. The target deviation item is the one with a contribution greater than the preset value.

[0070] S14: determining a target deviation item whose contribution is greater than a preset value, adjusting a target deviation range corresponding to the target deviation item, and outputting the deviation range after the target measurement item meets the standard.

[0071] Adjust the target deviation range corresponding to the target deviation item, and re-simulate the assembly calculation of the assembly model based on the deviation range after the target deviation item is adjusted, until the tolerance analysis result determines that the target measurement item meets the standard, and then output the deviation range after the target deviation item is adjusted.

[0072] The present application provides an assembly tolerance analysis method for a structural part, including: obtaining a three-dimensional model library of the structural part, determining a reference part and a part to be assembled from the three-dimensional model library, and constructing an assembly model of the reference part and the part to be assembled; adding a deviation range of a deviation item to the assembly model, and establishing a measurement item of the assembly model; performing a simulated assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result; determining a target measurement item that does not meet the standard and a contribution of each deviation item to the target measurement item according to the tolerance analysis result; determining a target deviation item whose contribution is greater than a preset value, adjusting a target deviation range corresponding to the target deviation item, and outputting the adjusted deviation range of the target deviation item after the target measurement item meets the standard. The assembly model is obtained by simulating the assembly of the structural part, and the tolerance analysis result is obtained by simulating the assembly of the assembly model, and the target measurement item that does not meet the standard and the target deviation item that has a greater impact on the target measurement item are determined according to the tolerance analysis result, and the target deviation range of the target deviation item is adjusted to make the target measurement item meet the standard, and the adjusted deviation range is used as the standard for manufacturing and assembling the structural part, so as to reduce the generation of deviations in the actual assembly process and reduce the rework of the structural part due to deviations after the assembly is completed. In addition, adjusting the target deviation range corresponding to the target deviation item that has a greater impact on the target measurement item, rather than blindly adjusting the deviation range of all deviation items, can reduce unnecessary adjustments and improve overall work efficiency. It also avoids the risk of introducing new problems by adjusting the deviation range of deviation items with smaller impacts.

[0073] Based on the above embodiments, the embodiments of the present application construct an assembly model of a reference part and a part to be assembled, including: determining the first characteristic surface of the reference part and the second characteristic surface of the part to be assembled according to the mating surfaces involved in the assembly of the reference part and the part to be assembled; setting three first positioning points on the first characteristic surface and three second positioning points on the second characteristic surface respectively; constraining the six degrees of freedom of the part to be assembled relative to the reference part based on the 3-2-1 positioning reference; wherein the three degrees of freedom of the part to be assembled are controlled by the X direction of the three second positioning points, the two degrees of freedom of the part to be assembled are controlled by the Y direction of the two second positioning points, and one degree of freedom of the part to be assembled is controlled by the Z direction of one second positioning point; setting the three first positioning points as target points, setting the three second positioning points as object points, and simulating the movement of each object point to each target point to construct an assembly model. Wherein, the mating surface refers to the surface on which two or more parts contact and mate.

[0074] For ease of understanding, the tolerance analysis simulation process is briefly described below using the end wall assembly process in the vehicle assembly process as an example. Figure 2 A schematic diagram of a base frame and end wall assembly provided in an embodiment of the present application, Figure 3 A first schematic diagram of a positioning point of an end wall component provided in an embodiment of the present application, Figure 4 A second schematic diagram of a positioning point of an end wall component provided in an embodiment of the present application, Figure 5 A schematic diagram of a positioning point constraint degree of freedom provided in an embodiment of the present application, Figure 6 This is a schematic diagram of a base frame component positioning point provided in an embodiment of the present application. Figure 2 As shown in the figure, the base frame is the reference part and the end wall is the part to be assembled. Figure 3 and Figure 4 As shown, the "3-2-1" positioning reference method is used to constrain the six degrees of freedom of the end wall relative to the base frame component. The mating surface at the edge of the bottom surface of the end wall is the second characteristic surface, and three second positioning points (dq-2, dq-3, dq-4) are set at the second characteristic surface; dq-2 is located on the bottom side of the end wall, and dq-3 and dq-4 are located on the bottom surface of the end wall. The three degrees of freedom of the end wall part (translation along the Z axis, rotation around the X axis, and rotation around the Y axis) are controlled by the X direction of the three positioning points, and two degrees of freedom (translation along the X axis and translation along the Y axis) are controlled by the Y direction of two of the positioning points. The remaining one degree of freedom (rotation around the Z axis) is controlled by the Z direction of one positioning point. For ease of understanding, as shown in Figure 4 As shown, the freedom constraints are explained. Figure 5 Primary means the main positioning surface. The three positioning points in the X direction form a main positioning surface to control the translation of the part along the Z axis, the rotation around the X axis, and the rotation around the Y axis. Figure 5 The Secondary in the figure represents the secondary positioning surface, which is formed by two points in the Y direction and controls the translation along the X axis and the translation along the Y axis. Figure 5 The Tertiary in represents the third positioning surface, which is formed by the Z direction of a positioning point and controls the rotation around the Z axis. Figure 6 As shown, the mating surface between the edge of the chassis and the end wall is the first characteristic surface, and three first positioning points (dj-2, dj-3, dj-4) are set on the first characteristic surface, where dj-3 and dj-4 are located on the upper surface of the chassis side beam, and dj-2 is located on the outer surface of the chassis cross beam. The three second positioning points of the end wall component correspond one-to-one to the three first positioning points of the chassis component, and the assembly of the end wall and the chassis is carried out according to the "three-point positioning" scheme, following the "3-2-1" positioning principle. The positioning and constraints of the reference parts and the parts to be assembled in the embodiment of the present application are realized by the "3-2-1" positioning reference principle, which can ensure accurate assembly and motion control between the reference parts and the parts to be assembled. The three first positioning points are set as target points, the three second positioning points are set as object points, and each object point is simulated and moved to each target point to realize the simulated assembly of the assembly model. Through simulated assembly, the embodiment of the present application can discover potential design problems and assembly errors before actual manufacturing, thereby reducing errors and rework in actual assembly. Reducing trial and error and modifications in actual assembly can significantly reduce material waste and labor costs.

[0075] Based on the above embodiment, after adjusting the target deviation range corresponding to the target deviation item, the embodiment of the present application further includes: after narrowing the target deviation range to a preset deviation range, if the target measurement item still does not meet the standard, adjusting the assembly method of the assembly model until the target measurement item meets the standard; wherein the preset deviation range is a minimum deviation range limited by manufacturing and assembly accuracy.

[0076] The embodiment of the present application takes into account that the target deviation range corresponding to the target deviation item cannot be reduced blindly in order to make the target measurement item meet the standard, and the accuracy that can be achieved in actual manufacturing and assembly should also be considered. For example, after the deviation range of the flatness of the bottom surface of the end wall is reduced to less than 0.1mm, the target measurement item meets the standard. However, in the actual manufacturing process, when the manufacturing machine manufactures the end wall, it cannot meet the deviation range of the flatness of the bottom surface of the wall less than 0.1mm. Then, the deviation range of the flatness of the bottom surface of the wall is less than 0.1mm, which will not be able to guide the actual production and manufacturing. Therefore, after the target deviation range is reduced to the preset deviation range, the target measurement item in the embodiment of the present application still does not meet the standard, and the assembly method of the assembly model is further adjusted. The embodiment of the present application does not specifically limit how to adjust the assembly method of the assembly model. The assembly model of the reference part and the part to be assembled is constructed based on the assembly features of the reference part and the assembly features of the part to be assembled. The assembly features include a feature surface located on the feature surface. The positioning point, and the assembly method of the assembly model can be adjusted to adjust the position of the positioning point on the feature surface, or add a new positioning point on the feature surface.

[0077] Based on the above embodiments, the embodiments of the present application add a deviation range of a deviation item to an assembly model, including: obtaining an assembly process file to obtain deviation items related to each structural part and a deviation value corresponding to each deviation item; determining the target positioning points and / or target feature surfaces involved in the deviation items, and adding a deviation range of the target feature points and / or target feature surfaces according to the deviation values ​​corresponding to the deviation items.

[0078] After the assembly model is established, it is necessary to add deviation items and deviation values ​​corresponding to the deviation items on the feature surfaces and / or feature points of the corresponding parts in the model according to the dimensional tolerance and form and position tolerance information provided by the actual assembly process process information. For the assembly process of the end wall and the base frame involved, the deviation values ​​that need to be considered are shown in Table 1.

[0079] Table 1 Deviations that need to be defined

[0080]

[0081] How to add a deviation range is explained using some positioning points on the chassis. For positioning point dj-2, which is located on the side of the chassis end beam and is affected by the flatness of the end beam, in order to reflect the flatness deviation, the positioning point dj-2 is bound to the characteristic surface of the side of the end beam, and a flatness deviation range of ≤2mm is added to the characteristic surface of the side of the end beam; at the same time, the positioning point dj-2 is also affected by the error in the length direction of the chassis tooling positioning accuracy, so it is also necessary to add a 2mm deviation range along the length direction for the positioning point dj-2. Since the side beam and the end beam plane positioning point have a deviation of (-1, 1) mm, it is necessary to add a circular deviation range with a radius of 1mm in the side plane of the end beam for the positioning point dj-2 to reflect the fluctuation of the positioning point within the side range.

[0082] Based on the above embodiments, the embodiment of the present application establishes measurement items of the assembly model, including: determining the type of measurement items; wherein the types of measurement items include point-to-point measurement items, point-to-surface measurement items, and surface-to-surface measurement items; adding measurement points and / or measurement surfaces to the reference parts and the parts to be assembled corresponding to the assembly model according to the types of measurement items, and setting the error tolerance range for each measurement item according to the product inspection requirements. That is, measurement points and / or measurement surfaces can be added to the reference parts, and correspondingly, measurement points and / or measurement surfaces can be added to the parts to be assembled.

[0083] After the deviation is defined, determine the calculation results that need to be output by the tolerance analysis according to the measurement items required by the process file, and define them through the "Measurement" option in the software. If it is a point-to-point measurement item, add the first measurement point on the reference part corresponding to the assembly model, and add the second measurement point on the part to be assembled corresponding to the assembly model to establish the point-to-point measurement item of the assembly model. For example: In order to calculate the deviation of the center line of the end wall width center and the end beam width center in the vehicle body width direction, establish a measurement point 1 at the top center of the end wall door frame, and establish a measurement point 2 at the corresponding position of the chassis end beam. In the "Measurement" tab, establish a point-to-point measurement item between these two measurement points, and add an error tolerance range of (-2, 2) mm.

[0084] Based on the above embodiments, the embodiments of the present application adjust the assembly method of the assembly model, including: determining the target axis that has the greatest impact on the stability of the assembly model; determining a first group of positioning points that control the rotation of the part to be assembled relative to the reference part around the target axis; determining a second group of positioning points of the assembly model involved in the target measurement item, and adjusting the position of each positioning point in the second group of positioning points to reduce the distance between each positioning point in the second group of positioning points and the plane where the first group of positioning points are located.

[0085] Since the distribution of positioning points determines the stability of each part when it rotates around a specific axis, when designing positioning points, priority is usually given to controlling the rotation of axes that can provide stability. For ease of understanding, the following example illustrates that for the deviation of the end wall width and the center line of the buffer beam in the vehicle width direction, the deviation rate of the difference between the center of the end wall width and the center of the buffer beam in the vehicle width direction is about 35%. The qualified rate of assembly according to the existing positioning method is low and needs to be adjusted. Through tolerance simulation analysis, it can be seen that under this positioning method, the difference between the center line of the end wall and the chassis cannot meet the requirements of the process file, and the positioning method needs to be adjusted. According to the positioning method defined in the assembly model, the layout of the three groups of positioning points has a great influence on the assembly deviation of the parts. Two of the three groups of positioning points (dq-2, dj-2), (dq-3, dj-4) and (dq-4, dj-3) are located in the XY plane, and one group is located in the YZ plane. The rotation of the end wall relative to the chassis around the X axis is only controlled by the group of positioning points dq-2 and dj-2. The center line deviation rate of the end wall width center and the buffer beam center in the vehicle body width direction is large. Therefore, it is considered to adjust a group of positioning points dq-3 and dj-4 on the XY plane to be close to the YZ plane to control the rotation of the X axis and improve stability. After the positioning method is adjusted, the end wall and chassis assembly model under the existing positioning method is simulated and calculated 10,000 times. The tolerance analysis results show that the deviation rate is 1.04%, which is greatly improved compared with the original positioning method, proving that the assembly state is stable and can meet the requirements of the process file. It can be considered that the adjusted positioning method has achieved the optimization of the deviation problem in the assembly process.

[0086] In the above embodiments, the assembly tolerance analysis method of the structural parts is described in detail, and the present application also provides an embodiment corresponding to the assembly tolerance analysis device of the structural parts. It should be noted that the present application describes the embodiments of the device part from two perspectives, one is based on the functional module perspective, and the other is based on the hardware perspective.

[0087] Figure 7 A structural diagram of an assembly tolerance analysis device for a structural part provided in an embodiment of the present application, such as Figure 7 As shown, a structural component assembly tolerance analysis device comprises:

[0088] The construction module 10 is used to obtain a three-dimensional model library of structural parts, determine the reference parts and the parts to be assembled from the three-dimensional model library, and construct assembly models of the reference parts and the parts to be assembled.

[0089] The adding module 11 is used to add the deviation range of the deviation item to the assembly model and establish the measurement item of the assembly model.

[0090] The simulated assembly calculation module 12 is used to perform simulated assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result.

[0091] The determination module 13 is used to determine the target measurement items that do not meet the standards and the contribution of each deviation item to the target measurement item according to the tolerance analysis result.

[0092] The deviation range adjustment module 14 is used to determine the target deviation item whose contribution is greater than a preset value, adjust the target deviation range corresponding to the target deviation item, and output the deviation range after the target measurement item meets the standard.

[0093] In a feasible embodiment, the building blocks include:

[0094] A first determining unit, used to determine a first characteristic surface of the reference part and a second characteristic surface of the part to be assembled according to the mating surfaces involved in the assembly of the reference part and the part to be assembled;

[0095] A setting unit, used for setting three first positioning points on the first characteristic surface and three second positioning points on the second characteristic surface respectively;

[0096] A constraint unit is used to constrain the six degrees of freedom of the part to be assembled relative to the reference part based on the 3-2-1 positioning reference; wherein three degrees of freedom of the part to be assembled are controlled by the X direction of three second positioning points, two degrees of freedom of the part to be assembled are controlled by the Y direction of two second positioning points, and one degree of freedom of the part to be assembled is controlled by the Z direction of one second positioning point;

[0097] The construction unit is used to set the three first positioning points as target points, set the three second positioning points as object points, and simulate moving each object point to each target point to construct an assembly model.

[0098] In a feasible embodiment, it also includes:

[0099] The assembly mode adjustment module is used to adjust the assembly mode of the assembly model until the target measurement item meets the standard after the target deviation range is narrowed to the preset deviation range, if the target measurement item still does not meet the standard; wherein the preset deviation range is the minimum deviation range limited by the manufacturing and assembly accuracy.

[0100] In a feasible embodiment, the adding module includes:

[0101] An acquisition unit is used to acquire assembly process files, obtain deviation items related to each structural part and deviation values ​​corresponding to each deviation item;

[0102] The first adding unit is used to determine the target positioning point and / or target feature surface involved in the deviation item, and add the deviation range of the target feature point and / or target feature surface according to the deviation value corresponding to the deviation item.

[0103] In a feasible embodiment, the adding module includes:

[0104] A second determining unit is used to determine the type of the measurement item; wherein the type of the measurement item includes a point-to-point measurement item, a point-to-plane measurement item, and a plane-to-plane measurement item;

[0105] The second adding unit is used to add measuring points and / or measuring surfaces to the reference parts and the parts to be assembled corresponding to the assembly model according to the types of the measuring items, and to set the error tolerance range for each measuring item according to the product inspection requirements.

[0106] In a feasible embodiment, the assembly mode adjustment module includes:

[0107] A third determination unit is used to determine the target axis that has the greatest impact on the stability of the assembly model;

[0108] A fourth determination unit, used to determine a first set of positioning points for controlling the rotation of the part to be assembled relative to the reference part around the target axis;

[0109] The fifth determining unit is used to determine a second group of positioning points of the assembly model involved in the target measurement item, and adjust the position of each positioning point in the second group of positioning points to reduce the distance between each positioning point in the second group of positioning points and the plane where the first group of positioning points are located.

[0110] In a feasible embodiment, the simulation assembly calculation module includes:

[0111] A change unit, used to change the deviation item when each deviation item satisfies the corresponding deviation range;

[0112] A simulated assembly calculation unit is used to perform simulated assembly calculation on the assembly model after each deviation item is changed according to the measurement item;

[0113] The statistical analysis unit is used to perform statistical analysis on multiple simulation assembly calculation results to obtain tolerance analysis results.

[0114] Since the embodiments of the apparatus part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the apparatus part, which will not be repeated here.

[0115] Figure 8 A structural diagram of another structural component assembly tolerance analysis device provided in an embodiment of the present application, such as Figure 8 As shown, the assembly tolerance analysis device for a structural part comprises: a memory 20 for storing a computer program;

[0116] The processor 21 is used to implement the steps of the assembly tolerance analysis method of the structural parts in the above embodiment when executing the computer program.

[0117] The assembly tolerance analysis device for a structural component provided in this embodiment may include, but is not limited to, a smart phone, a tablet computer, a laptop computer, or a desktop computer.

[0118] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 can be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0119] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 20 is at least used to store the following computer program 201, wherein, after the computer program is loaded and executed by the processor 21, it can implement the relevant steps of the assembly tolerance analysis method of the structural parts disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 202 may include Windows, Unix, Linux, etc. Data 203 may include but is not limited to a three-dimensional model library, etc.

[0120] In some embodiments, the assembly tolerance analysis device for a structural component may further include a display screen 22 , an input / output interface 23 , a communication interface 24 , a power supply 25 , and a communication bus 26 .

[0121] Those skilled in the art will understand that Figure 8 The structure shown in the figure does not constitute a limitation on the assembly tolerance analysis device of the structural member, and may include more or less components than those shown in the figure.

[0122] The assembly tolerance analysis device of a structural part provided in an embodiment of the present application includes a memory and a processor. When the processor executes a program stored in the memory, the method can be implemented as follows: obtaining a three-dimensional model library of the structural part, determining a reference part and a part to be assembled from the three-dimensional model library, and constructing an assembly model of the reference part and the part to be assembled; adding a deviation range of a deviation item to the assembly model, and establishing a measurement item of the assembly model; performing a simulated assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result; determining a target measurement item that does not meet the standard and a contribution of each deviation item to the target measurement item according to the tolerance analysis result; determining a target deviation item whose contribution is greater than a preset value, adjusting a target deviation range corresponding to the target deviation item, and outputting the adjusted deviation range of the target deviation item after the target measurement item meets the standard.

[0123] Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps recorded in the assembly tolerance analysis method of a structural part in the above method embodiment are implemented.

[0124] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0125] The above is a detailed introduction to the assembly tolerance analysis method, device and medium of a structural part provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0126] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A method for analyzing assembly tolerance of a structural part, characterized in that: include: Acquire a three-dimensional model library of structural parts, determine reference parts and parts to be assembled from the three-dimensional model library, and construct assembly models of the reference parts and parts to be assembled; adding a deviation range of a deviation item to the assembly model, and establishing a measurement item of the assembly model; Performing simulation assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result; Determine the target measurement item that does not meet the standard and the contribution of each deviation item to the target measurement item according to the tolerance analysis result; Determine a target deviation item whose contribution is greater than a preset value, adjust a target deviation range corresponding to the target deviation item, and output the adjusted deviation range of the target deviation item after the target measurement item meets the standard.

2. The assembly tolerance analysis method of a structural component according to claim 1, characterized in that: The step of constructing the assembly model of the reference part and the part to be assembled comprises: Determining a first characteristic surface of the reference part and a second characteristic surface of the part to be assembled according to the mating surfaces involved in the assembly of the reference part and the part to be assembled; respectively setting three first positioning points on the first characteristic surface and three second positioning points on the second characteristic surface; Based on the 3-2-1 positioning reference, the six degrees of freedom of the part to be assembled relative to the reference part are constrained; wherein three degrees of freedom of the part to be assembled are controlled by the X direction of three second positioning points, two degrees of freedom of the part to be assembled are controlled by the Y direction of two second positioning points, and one degree of freedom of the part to be assembled is controlled by the Z direction of one second positioning point; The three first positioning points are set as target points, the three second positioning points are set as object points, and each object point is simulated and moved to each target point to construct the assembly model.

3. The assembly tolerance analysis method of a structural component according to claim 2, characterized in that: After adjusting the target deviation range corresponding to the target deviation item, the method further includes: After the target deviation range is narrowed to the preset deviation range, if the target measurement item still does not meet the standard, adjusting the assembly method of the assembly model until the target measurement item meets the standard; The preset deviation range is a minimum deviation range limited by manufacturing and assembly accuracy.

4. The assembly tolerance analysis method of a structural component according to claim 2, characterized in that: The deviation range of adding the deviation item to the assembly model includes: Acquire the assembly process file, obtain the deviation items related to each structural part and the deviation values ​​corresponding to each deviation item; The target positioning point and / or target feature surface involved in the deviation item is determined, and the deviation range of the target feature point and / or the target feature surface is added according to the deviation value corresponding to the deviation item.

5. The assembly tolerance analysis method of a structural component according to claim 1, characterized in that: The measurement items for establishing the assembly model include: Determine the type of the measurement item; wherein the type of the measurement item includes a point-to-point measurement item, a point-to-plane measurement item, and a plane-to-plane measurement item; According to the type of the measurement item, measurement points and / or measurement surfaces are added to the reference part and the part to be assembled corresponding to the assembly model, and the error tolerance range is set for each measurement item according to the product inspection requirements.

6. The assembly tolerance analysis method of a structural component according to claim 3, characterized in that: The adjusting the assembly mode of the assembly model includes: determining a target axis that has the greatest impact on the stability of the assembly model; Determine a first set of positioning points for controlling the rotation of the part to be assembled relative to the reference part around the target axis; A second group of positioning points of the assembly model involved in the target measurement item is determined, and a position of each positioning point in the second group of positioning points is adjusted to reduce a distance between each positioning point in the second group of positioning points and a plane where the first group of positioning points are located.

7. The assembly tolerance analysis method of a structural component according to claim 1, characterized in that: The step of performing simulation assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result includes: Changing the deviation item under the condition that each deviation item satisfies the corresponding deviation range; Performing simulated assembly calculation on the assembly model after each change of the deviation item according to the measurement item; The tolerance analysis result is obtained by performing statistical analysis on multiple simulated assembly calculation results.

8. A structural component assembly tolerance analysis device, characterized in that: include: A construction module is used to obtain a three-dimensional model library of structural parts, determine reference parts and parts to be assembled from the three-dimensional model library, and construct assembly models of the reference parts and parts to be assembled; An adding module, used for adding a deviation range of a deviation item to the assembly model and establishing a measurement item of the assembly model; A simulated assembly calculation module, used for performing simulated assembly calculation on the assembly model according to the deviation range of the deviation item and the measurement item to obtain a tolerance analysis result; A determination module, used to determine the target measurement item that does not meet the standard and the contribution of each deviation item to the target measurement item according to the tolerance analysis result; The deviation range adjustment module is used to determine the target deviation item whose contribution is greater than a preset value, adjust the target deviation range corresponding to the target deviation item, and output the deviation range after the target measurement item meets the standard.

9. An assembly tolerance analysis device for a structural part, characterized in that: comprising a memory for storing a computer program; A processor is used to implement the steps of the assembly tolerance analysis method of a structural component as claimed in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the assembly tolerance analysis method of a structural component according to any one of claims 1 to 7 are implemented.

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