X-ray tube anode target disc fastening nut structure design and optimization method
By constructing parametric models and simulation analysis methods, the inner and outer diameters and preloading forces of the anode target disk fastening nut of the X-ray tube are optimized, which solves the problem of time-consuming and labor-consuming design and optimization in the prior art, and achieves efficient design and optimization, improving the stability and safety of the equipment.
Patent Information
- Application Number
- CN202411586296.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-03-18
AI Technical Summary
In the prior art, when designing and optimizing the tightening nut of the anode target disk of the X-ray tube, there are problems such as time-consuming, labor-consuming and consumables, and it is difficult to meet the stability and safety requirements of the anode target disk under high temperature and high speed rotation and other operating conditions.
By constructing a parametric model and combining simulation analysis methods, the inner and outer diameters and preloading forces of the fastening nuts are optimized to ensure that the simulation pressure and structural stress of the pressing contact surface meet the design requirements.
The structural size of the fastening nut and the preload force of the bolt are optimized, the structural design efficiency of the X-ray tube anode target disc tightening nut is improved, the R&D cycle is shortened, and the looseness or breaking faults are reduced.
Smart Images
Figure CN119646996A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of research and development of fastening nuts, and in particular to a structural design and optimization method of a fastening nut for an anode target of an X-ray tube. Background Art
[0002] The anode target is the core component for generating X-rays in CT equipment. Its function is to receive high-speed electron impact and generate X-rays. During the operation of the CT equipment, the anode target needs to maintain the following properties for a long time: high X-ray generation efficiency, good high temperature tolerance, high melting point, low evaporation rate, high heat capacity and high thermal conductivity under high temperature, high-speed rotation, multiple start-stop shock and other working conditions. Therefore, when the anode target is working, its fastening nut must maintain high temperature resistance, thermal shock resistance, vibration shock resistance, high mechanical strength, high thermal conductivity and other properties for a long time, and it must also ensure that the anode target has a certain tightening torque to ensure that the anode target is not damaged due to over-tightening, nor loosened due to over-loosening, so as to ensure the stability and safety of the anode target during the operation of the X-ray tube in the CT equipment, thereby ensuring the service life of the X-ray tube.
[0003] At present, there are no related inventions in engineering for the structural design and optimization and improvement of the fastening nuts of the anode target of the X-ray tube. There are many studies on the preload force of the bolts, such as the research on the preload force of standard bolt parts, but these methods are prone to problems such as time-consuming, labor-consuming, and consumables.
[0004] Therefore, a new X-ray tube anode target fastening nut structure design and optimization method is needed. Summary of the invention
[0005] According to one aspect of the present invention, a method for structural design and optimization of a fastening nut of an anode target of an X-ray tube is provided, the method comprising the steps of: obtaining fastening design requirements of an anode target of an X-ray tube, constructing a parameterized model of an anode target and a fastening nut according to two-dimensional design information of a fastening gasket, structural properties of the material at room temperature and at high temperature, thermal properties, and compression and rebound characteristics of the fastening gasket material in the fastening design requirements; constructing a simulation analysis model according to the parameterized model of the anode target and the fastening nut and the design allowable preload of a bolt; determining a simulation analysis result according to the simulation analysis model, the simulation analysis result including a simulated pressure of a compression contact surface of the fastening nut and a simulated structural stress of the fastening nut; if the simulation analysis result does not meet the fastening design requirements, setting simulation variables of the fastening nut according to the parameterized model, including a simulated inner diameter and a simulated outer diameter of the fastening nut, performing simulation variable value search in respective simulation intervals of the simulated inner diameter and the simulated outer diameter, and obtaining a value search result; determining an optimized size, an optimized preload, and an optimized pressing force of the fastening nut according to the value search result.
[0006] Optionally, in the method according to the present invention, the fastening design requirements include a design allowable pressure and a maximum allowable structural stress, and the method further includes: if the simulated pressure of the clamping contact surface is less than the design allowable pressure and / or the simulated structural stress of the fastening nut is greater than the maximum allowable structural stress, then it is judged that the simulation analysis results do not meet the fastening design requirements.
[0007] Optionally, in the method according to the present invention, the simulation interval includes an initial simulation inner diameter interval [a1, b1] and an initial simulation outer diameter interval [a2, b2], and the simulation variable value search is performed in the simulation intervals of the simulation inner diameter and the simulation outer diameter to obtain the value search results, including: determining the median c1 of the initial simulation inner diameter interval and the median c2 of the initial simulation outer diameter interval according to the initial simulation inner diameter interval and the initial simulation outer diameter interval; when the simulation values of the inner and outer diameters of the fastening nut are a1 and a2, c1 and c2, b1 and b2, respectively, determining that the corresponding simulation pressure of the clamping contact surface and the simulation structural stress of the fastening nut are: P a and σ a , P c and σ c , P b and σ b According to P a and σ a , P c and σ c , P b and σ b Determine the correlation between the simulated pressure and simulated structural stress and the inner and outer diameters of the fastening nut.
[0008] Optionally, in the method according to the present invention, according to P a and σ a , P c and σ c , P b and σ b Determine the correlation between the simulated pressure and the simulated structural stress and the inner and outer diameters of the fastening nut: If P c >P a , P c <P b , while σ c >σ a , σ c <σ b , it is determined that the simulated pressure and simulated structural stress are positively correlated with the inner and outer diameters of the fastening nut; if P c <P a and / or σ c <σ a , it is determined that the simulated pressure and simulated structural stress are negatively correlated with the inner and outer diameters of the fastening nut.
[0009] Optionally, the method according to the present invention also includes: if the simulated pressure and the simulated structural stress are positively correlated with the inner and outer diameters of the fastening nut, then determining the second simulated inner diameter interval [b1, c1] according to the median c1 of the initial simulation inner diameter interval and the upper limit b1 of the initial simulation inner diameter interval; determining the second simulated outer diameter interval [b2, c2] according to the median c2 of the initial simulation outer diameter interval and the upper limit b2 of the initial simulation inner diameter interval.
[0010] Optionally, the method according to the present invention also includes: if the simulated pressure and the simulated structural stress are negatively correlated with the inner and outer diameters of the fastening nut, then determining the second simulated inner diameter interval [a1, c1] according to the lower limit value a1 of the initial simulation inner diameter interval and the median value c1 of the initial simulation inner diameter interval; and determining the second simulated outer diameter interval [a2, c2] according to the lower limit value a1 of the initial simulation outer diameter interval and the median value c2 of the initial simulation outer diameter interval.
[0011] Optionally, the method according to the present invention also includes: determining the median of the second simulation inner diameter interval and the median of the second simulation outer diameter interval according to the second simulation inner diameter interval and the second simulation outer diameter interval; redetermining the correlation between the simulation pressure and the simulation structural stress and the inner and outer diameters of the fastening nut according to the second simulation inner diameter interval, the median of the second simulation inner diameter interval, the second simulation outer diameter interval, and the median of the second simulation outer diameter interval; redetermining the simulation inner diameter interval and the simulation outer diameter interval according to the correlation between the simulation pressure and the simulation structural stress and the inner and outer diameters of the fastening nut until the condition for stopping the simulation variable search is reached.
[0012] Optionally, in the method according to the present invention, the step of determining the optimized preload force includes: determining the area of the optimized clamping contact surface according to the optimized size of the fastening nut; and determining the optimized preload force according to the area of the optimized clamping contact surface and the optimized pressure.
[0013] According to another aspect of the present invention, a computing device is provided, comprising: one or more processors; a memory; and one or more devices, wherein the one or more devices include instructions for executing a method for designing and optimizing a fastening nut structure of an anode target of an X-ray tube.
[0014] According to another aspect of the present invention, a computer-readable storage medium stores one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to execute a method for designing and optimizing a fastening nut structure for an anode target of an X-ray tube.
[0015] The invention discloses a method for designing and optimizing the fastening nut structure of an anode target of an X-ray tube. First, according to the fastening design requirements of the anode target and the initial design scheme of the fastening nut, a simulation analysis model of the fastening nut of the anode target is constructed, and the compression contact surface pressure of the fastening nut of the anode target is simulated and analyzed to obtain the compression contact surface pressure and the structural stress of the fastening nut. The compression contact surface pressure and the structural stress of the fastening nut are respectively compared with the corresponding values in the fastening design requirements. When the design requirements are not met, an optimization method is further adopted to optimize the size of the fastening nut, and finally the optimal design scheme of the size of the fastening nut is determined. The method for designing and optimizing the fastening nut structure of an anode target of an X-ray tube proposed by the invention can not only optimize the structural size of the fastening nut, but also optimize the bolt preload. The method adopts a simulation analysis method to optimize the design of the nut structural size and the bolt preload, which can greatly improve the structural design efficiency of the fastening nut of the anode target of an X-ray tube, shorten the research and development cycle, and reduce the loosening of the anode target or the breakage of the fastening nut, and has great scientific research and engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] To achieve the above and related purposes, certain illustrative aspects are described herein in conjunction with the following description and accompanying drawings, which indicate various ways in which the principles disclosed herein can be practiced, and all aspects and their equivalents are intended to fall within the scope of the claimed subject matter. The above and other purposes, features and advantages of the present disclosure will become more apparent by reading the following detailed description in conjunction with the accompanying drawings. Throughout the present disclosure, the same reference numerals generally refer to the same parts or elements.
[0017] Figure 1 A schematic diagram showing a structural design and optimization method of an anode target fastening nut of an X-ray tube according to an exemplary embodiment of the present invention is shown;
[0018] Figure 2 A schematic diagram showing a tightening nut optimization process according to an exemplary embodiment of the present invention is shown;
[0019] Figure 3 A schematic diagram of a tightening contact surface of a fastening nut according to an exemplary embodiment of the present invention is shown;
[0020] Figure 4 A schematic diagram showing the code of a parameterized model according to an exemplary embodiment of the present invention;
[0021] Figure 5 A schematic diagram of a simulation analysis model of a fastening nut according to an exemplary embodiment of the present invention is shown;
[0022] Figure 6 A schematic diagram of a pressure cloud diagram and a structural stress cloud diagram of a compressed contact surface according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION
[0023] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to enable the scope of the present disclosure to be fully conveyed to those skilled in the art. The same reference numerals generally refer to the same components or elements.
[0024] In order to ensure that the anode target has a certain tightening torque, designers often use methods such as experimental testing, empirical estimation or finite element simulation to carry out the structural design of the fastening nut. In view of the problems of the current prior art, the present invention proposes a structural design and optimization method for the fastening nut of the anode target of an X-ray tube. This structural design method can not only optimize the structural dimensions of the nut, but also optimize the bolt preload. At the same time, the method uses a simulation analysis method to optimize the nut structure and bolt preload design, which can greatly improve the structural design efficiency of the fastening nut of the anode target of the X-ray tube, shorten the research and development cycle, and reduce the loosening of the anode target or the breakage of the fastening nut, and has great scientific research and engineering application value.
[0025] Figure 1 FIG. 1 is a schematic diagram showing a structural design and optimization method of an anode target fastening nut of an X-ray tube according to an exemplary embodiment of the present invention. Figure 1 As shown, firstly, step 110 is executed to obtain the fastening design requirements of the anode target of the X-ray tube, and a parametric model of the anode target and the fastening nut is constructed according to the two-dimensional design information of the fastening gasket in the fastening design requirements, the structural properties of the material at room temperature and high temperature, the thermal properties, and the compression and rebound characteristics of the fastening gasket material.
[0026] According to one embodiment of the present invention, the present invention first collects and organizes the fastening design requirements of the anode target of the X-ray tube, including: the design allowable clamping force of the fastening nut, the design allowable pressure of the clamping contact surface of the fastening nut, the design allowable deformation data of the fastening nut, the initial design scheme of the fastening nut (including the initial design size of the fastening nut, the material compressive strength of the fastening nut) and fastening gasket material and other related information, including two-dimensional design information, structural properties of the material at room temperature and high temperature, thermal properties, and compression and rebound characteristics of the fastening gasket material.
[0027] According to an embodiment of the present invention, the present invention selects a certain type of CT tube, collects the fastening design requirements of the anode target plate and the geometric parameters of the fastening nut in the initial design scheme, including the outer diameter, inner diameter, nut thickness of the compression contact surface of the fastening nut, nut, gasket, anode target plate, and material characteristics, as shown in Table 1;
[0028] Table 1 Example of material properties of anode target fastening nut
[0029] property Room temperature Density / t / mm3 10.170e-9 Young's modulus MPa 320000 Poisson's ratio 0.2 Specific heat / J / tk 0.25e6 Thermal conductivity / W / mm.k 0.122 Thermal expansion coefficient / k 5.3×10-6 Tensile strength / MPa 750 Yield strength / MPa 650
[0030] Then, step 120 is executed to construct a simulation analysis model according to the parameterized models of the anode target plate and the fastening nut and the design allowable preload of the bolt.
[0031] Figure 2 FIG. 2 shows a schematic diagram of a tightening nut optimization process according to an exemplary embodiment of the present invention. Figure 2 As shown in FIG. 1 , after identifying the design requirements for the clamping force of the anode target, the initial design of the clamping size of the fastening nut is also determined, that is, according to the fastening design requirements of the anode target and the initial design size of the fastening nut, the area S of the clamping contact surface of the fastening nut is calculated. 12 . Figure 3 FIG. 2 shows a schematic diagram of a tightening nut compression contact surface according to an exemplary embodiment of the present invention. Figure 3 As shown, the pressing contact surface is a circular ring determined according to r1 and r2.
[0032] The area of the pressed contact surface S 12 It can be calculated according to the following formula:
[0033] S 12 =π*(r2 2 -r1 2 )
[0034] Among them, r1 and r2 are the inner circle radius (inner diameter) and outer circle radius (outer diameter) of the fastening nut, respectively, in mm.
[0035] like Figure 2 As shown, the preload force of the bolts under the initial structure is also calculated, and when the parametric simulation modeling of the fastening nut is performed, a geometric digital model is generated, and then the simulation analysis digital modeling is performed.
[0036] According to the area S of the pressed contact surface 12 And the design allowable pressure P of the clamping contact surface in the fastening design requirements 设计 , calculate the design allowable preload F of the bolt corresponding to the fastening nut 设计 (The design allowable preload is also called the design allowable axial force), the formula is as follows:
[0037] F 设计 =S 12 *P 设计
[0038] F 设计 It is the design allowable preload force, the unit is N.
[0039] Then, according to the following formula, the design allowable preload force F of the bolt is 设计 Converted to the allowable design tightening force T of the bolt 设计 , so as to facilitate installation by installers;
[0040] T 设计 =k*d*F 设计
[0041] Among them, T 设计 is the design allowable clamping force of the bolt, in Nm; d is the nominal thread diameter of the bolt, in m; k is the torque coefficient, which is related to the roughness of the nut seat surface and the pitch and can be determined accordingly.
[0042] According to one embodiment of the present invention, based on the anode target plate fastening design requirements and the nut design dimensions, the tightening contact area of the fastening nut is calculated as S = π*(20^2-10^2) = 942 mm 2 ; Since the design allowable pressure of the compression contact surface = 50MPa, the design allowable axial force of the bolt (i.e., the design allowable preload) F 设计 =S*P 设计 =47100N; According to the axial force and torque conversion formula, the axial force is converted into the clamping force T, taking k = 0.15, d = 0.01m, then T = F 设计 *0.15*0.01=70.65NM.
[0043] According to one embodiment of the present invention, the present invention can use CAD and CAE software tools to construct a parametric model of the anode target plate and the fastening nut based on the two-dimensional design information in the fastening design requirements, the structural properties of the material at room temperature and high temperature, the thermal properties, and the compression and rebound characteristics of the fastening gasket material.
[0044] Figure 4 A schematic diagram showing the code of a parameterized model according to an exemplary embodiment of the present invention is shown. Figure 4 As shown, the variables can be defined through the code of the parametric model, and then the variables are optimized cyclically. For example, the inner diameter and outer diameter of the fastening nut are defined as variables. In each round of optimization cycle, the inner diameter and outer diameter are changing, so that the fastening nut product corresponding to the parametric model is also changing. Then determine the constraint boundary of the bolt preload (including the yield strength of the material, the diameter and length of the bolt, the friction coefficient between the bolt and the nut, etc.), and apply the design allowable preload in the parametric model; then, based on the parametric model, use the finite element simulation analysis method to build a simulation analysis model.
[0045] Figure 5 FIG. 1 is a schematic diagram of a simulation analysis model of a fastening nut according to an exemplary embodiment of the present invention. Figure 5As shown, the simulation analysis model can be used to carry out simulation analysis of the clamping force of the anode target plate fastening nut, and extract the pressure of the clamping contact surface of the fastening nut and the structural stress data and deformation data of the fastening nut. Figure 6 A schematic diagram of a pressure cloud diagram and a structural stress cloud diagram of a compressed contact surface according to an exemplary embodiment of the present invention is shown.
[0046] According to one embodiment of the present invention, CAD and CAE software tools are used to construct a parametric model of the anode target plate and the fastening nut based on the collected information; then the pre-tightening force of the bolt of 47100N is applied to the parametric model, and then a simulation analysis model is constructed based on the parametric model using the finite element simulation analysis method; the simulation analysis model is used to carry out simulation analysis of the clamping force of the anode target plate fastening nut and extract the clamping contact surface pressure of the fastening nut, the structural stress data of the fastening nut, and the deformation data, etc. Among them, the tensile strength of the target plate cap material of 750MPa is used as the fault criterion for fracture, that is, when the maximum stress of the target plate cap structure reaches 750MPa, the fastening nut structure will crack.
[0047] Then, step 130 is performed to determine the simulation analysis results according to the simulation analysis model, and the simulation analysis results include the simulated pressure of the compression contact surface of the fastening nut and the simulated structural stress of the fastening nut. If the simulated pressure of the compression contact surface is less than the design allowable pressure and / or the simulated structural stress of the fastening nut is greater than the maximum allowable structural stress, it is judged that the simulation analysis results do not meet the fastening design requirements.
[0048] According to one embodiment of the present invention, based on the simulation analysis results of the compression stress of the anode target plate and the fastening nut, it can be further determined whether the pressure, structural stress and deformation of the compression contact surface of the fastening nut meet the tightening design requirements; when the simulated pressure of the compression contact surface of the fastening nut obtained by simulation is greater than the design allowable pressure, and the simulated structural stress of the fastening nut obtained by simulation is greater than the design requirement, the problem that the deformation data obtained by simulation is greater than the design allowable deformation data is solved, and an optimization algorithm, such as binary search method, Newton method, quasi-Newton method, conjugate gradient method, genetic method and other algorithms, is used to optimize the structural design parameters of the fastening nut and the bolt preload.
[0049] Subsequently, step 140 is executed. If the simulation analysis result does not meet the fastening design requirements, the simulation variables of the fastening nut are set according to the parameterized model, including the simulated inner diameter and the simulated outer diameter of the fastening nut, and the simulation variables are searched for values in the simulation intervals of the simulated inner diameter and the simulated outer diameter to obtain the search results.
[0050] The simulation interval includes an initial simulation inner diameter interval [a1, b1] and an initial simulation outer diameter interval [a2, b2]. The simulation variable value search is performed in the respective simulation intervals of the simulation inner diameter and the simulation outer diameter to obtain the value search results, including: determining the initial simulation inner diameter interval median c1 and the initial simulation outer diameter interval median c2 according to the initial simulation inner diameter interval and the initial simulation outer diameter interval;
[0051] According to the simulation values of the inner and outer diameters of the fastening nut are a1 and a2, c1 and c2, b1 and b2, the corresponding simulated pressure of the clamping contact surface and the simulated structural stress of the fastening nut are determined as follows: P a and σ a , P c and σ c , P b and σ b .
[0052] According to P a and σ a , P c and σ c , P b and σ b Determine the correlation between the simulated pressure and the simulated structural stress and the inner and outer diameters of the fastening nut, including: if P c >P a , P c <P b , while σ c >σ a , σ c <σ b , it is determined that the simulated pressure and simulated structural stress are positively correlated with the inner and outer diameters of the fastening nut; if P c <P a and / or σ c <σ a , it is determined that the simulated pressure and simulated structural stress are negatively correlated with the inner and outer diameters of the fastening nut.
[0053] If the simulated pressure and the simulated structural stress are positively correlated with the inner and outer diameters of the fastening nut, the second simulated inner diameter interval [b1, c1] is determined according to the median c1 of the initial simulation inner diameter interval and the upper limit b1 of the initial simulation inner diameter interval; the second simulated outer diameter interval [b2, c2] is determined according to the median c2 of the initial simulation outer diameter interval and the upper limit b2 of the initial simulation inner diameter interval.
[0054] If the simulated pressure and the simulated structural stress are negatively correlated with the inner and outer diameters of the fastening nut, the second simulated inner diameter interval [a1, c1] is determined according to the lower limit value a1 of the initial simulation inner diameter interval and the median value c1 of the initial simulation inner diameter interval; the second simulated outer diameter interval [a2, c2] is determined according to the lower limit value a1 of the initial simulation outer diameter interval and the median value c2 of the initial simulation outer diameter interval.
[0055] Determine the median of the second simulation inner diameter interval and the median of the second simulation outer diameter interval according to the second simulation inner diameter interval and the second simulation outer diameter interval; redetermine the correlation between the simulation pressure and the simulation structural stress and the inner and outer diameters of the fastening nut according to the second simulation inner diameter interval, the median of the second simulation inner diameter interval, the second simulation outer diameter interval, and the median of the second simulation outer diameter interval; redetermine the simulation inner diameter interval and the simulation outer diameter interval according to the correlation between the simulation pressure and the simulation structural stress and the inner and outer diameters of the fastening nut, until the condition for stopping the simulation variable search is reached.
[0056] According to one embodiment of the present invention, the present invention first organizes the input data of the parameterized model variables: sets the simulation intervals of the fastening nuts r1 and r2, such as the initial simulation interval [a1, b1] of r1, such as the initial simulation interval [a2, b2] of r2, wherein b1 and b2 are the initial upper bounds b, and a1 and a2 are the initial lower bounds a; sets the maximum pressure of the clamping contact surface of the fastening nut; sets the maximum structural stress of the fastening nut; sets the maximum number of cycles n, such as n=100; sets the optimization accuracy, such as setting it to f(simulation inner diameter interval upper limit, simulation outer diameter interval upper limit)-f(simulation inner diameter interval lower limit, simulation outer diameter interval lower limit)<1.0 -3 ;
[0057] Subsequently, the objective function of the simulation analysis model is set to function f(x) = f(fastening nut r1, fastening nut r2), and the obtained function value f(x) is the function value of the maximum pressure on the tightening contact surface of the fastening nut and the maximum structural stress of the fastening nut. The function value can be obtained through images and data of the simulation results of the simulation analysis model.
[0058] Calculate the midpoint of the value range of the parameters to be optimized r1 and r2, such as the midpoint of r1 c1 = (a1 + b1) / 2, the midpoint of r2 c2 = (a2 + b2) / 2;
[0059] When the values of r1 and r2 of the fastening nut are both taken as the lower bound, the simulation analysis model is used to perform simulation analysis to determine the value of the objective function f(a1, a2), and the simulation analysis results are obtained: the simulation pressure P of the tightening contact surface of the fastening nut a and simulated structural stress σ a ; When the values of r1 and r2 of the fastening nut are both taken as the midpoint, the simulation analysis model is used to perform simulation analysis to determine the value of the objective function f(c1, c2), and the simulation analysis results are obtained: the simulation pressure P of the tightening contact surface of the fastening nut c and the simulated structural stress σ of the fastening nut c ; When the values of r1 and r2 of the fastening nut are both taken as the upper bound, the simulation analysis model is used to perform simulation analysis to determine the value of the objective function f(b1, b2), and the simulation analysis results are obtained: the simulation pressure P of the tightening contact surface of the fastening nutb and the simulated structural stress σ of the fastening nut b ;
[0060] According to the simulation analysis results, the search space of r1 and r2 is narrowed down by the following steps:
[0061] According to the derivative calculation principle Determine the simulation analysis results P a and σ a , P c and σ c , P b and σ b The correlation between the simulated pressure, simulated structural stress and the inner and outer diameters of the fastening nut (including positive and negative correlations), x k-1 and x k-1 +Δ is the independent variable of the objective function f(x) of the simulation analysis model, and Δ is the increment of the independent variable.
[0062] If P c >P a , P c <P b , while σ c >σ a , σ c <σ b , then P a and σ a , P c and σ c , P b and σ b The simulation pressure and the simulation structural stress are positively correlated with the inner and outer diameters of the fastening nut. The optimal solution of r1 is determined to be in the interval [c1, b1]. Let a1 = c1 and update the optimization interval. The optimal solution of r2 is determined to be in the interval [c2, b2]. Let a2 = c2 and update the optimization interval.
[0063] If P c <P a and / or σ c <σ a , then P a and σ a , P c and σ c , P b and σ b The parameter simulation pressure and simulation structural stress are negatively correlated with the inner and outer diameters of the fastening nut. The optimal solution of r1 is determined to be in the interval [a1, c1]. Let b1 = c1 and update the optimization interval. The optimal solution of r2 is determined to be in the interval [a2, c2]. Let b2 = c2 and update the optimization interval.
[0064] Repeat the above steps, recalculate the midpoints c1 and c2 each time and calculate the corresponding objective function values, and then adjust the search intervals of r1 and r2 according to the objective function values;
[0065] According to one embodiment of the present invention, the condition for stopping the simulation variable value search is the maximum number of cycles, such as n=100, or setting the optimization accuracy, such as 1.0 -3 .
[0066] like Figure 2 As shown, the present invention determines whether the average pressure of the simulated contact surface, i.e., the pressure, meets the design requirements. If so, the optimized size is output and the design result is verified by experiment. If not, the fixed nut design parameter optimization model is continued. Design constraints, such as size, are constructed, a clamping objective function is constructed, and an optimal algorithm is selected for optimization and solution. During the solution process, it is determined whether the average pressure of the simulated contact surface meets the design requirements each time.
[0067] According to one embodiment of the present invention, the present invention organizes the optimization parameter input data: setting the value intervals of the fastening nuts r1 and r2, that is, the interval of r1 is [8,14] mm, and the value interval of r2 is [18,24] mm; setting the maximum clamping contact surface pressure of the fastening nut to 50 MPa; setting the maximum structural stress of the fastening nut to 750 MPa; setting the maximum number of cycles, such as n = 100; setting the optimization accuracy, such as 1.0 -3 .
[0068] Calculate the midpoint of the interval of the parameters to be optimized, that is, the midpoint of r1 is c1=(a1+b1) / 2=11mm, and the midpoint of r2 is c2=21mm; when the values of the fastening nuts r1 and r2 are both the midpoints c1 and c2, the simulation analysis model is used to perform simulation analysis and obtain the simulation analysis results, including the simulation pressure P of the pressing contact surface. c and the simulated structural stress σ of the fastening nut c When the values of the tightening nuts r1 and r2 are both the lower limit points a1 and a2, the simulation analysis model is used to perform simulation analysis to obtain the simulation analysis results, including the simulation pressure P of the pressing contact surface. a and simulated structural stress σ a When the values of the tightening nuts r1 and r2 are both taken as the upper limit points b1 and b2, the simulation analysis model is used to perform simulation analysis to obtain the simulation analysis results, including the simulation pressure P of the pressing contact surface. b and the simulated structural stress σ of the fastening nut b ;
[0069] According to the simulation analysis results a and σ a , P c and σ c , P b and σb , narrow the search space of r1 and r2 by following the steps below:
[0070] According to the derivative calculation principle, the simulation analysis result P is determined a and σ a , P c and σ c , P b and σ b The correlation between the simulated pressure and the simulated structural stress and the inner and outer diameters of the fastening nut (including positive and negative correlations);
[0071] If P c >P a , P c <P b , while σ c >σ a , σ c <σ b , then P a and σ a , P c and σ c , P b The and σb are positively correlated with the parameter simulation pressure and simulation structural stress and the inner and outer diameters of the fastening nut. The optimal solution of r1 is determined to be in the interval [c1, b1]. Let a1 = c1 and update the optimization interval of r1 to [11, 14] mm. The optimal solution of r2 is determined to be in the interval [c2, b2]. Let a2 = c2 and update the optimization interval of r2 to [21, 24] mm.
[0072] If P c <P a and / or σ c <σ a , then P a and σ a , P c and σ c , P b and σ b The parameter simulation pressure and simulation structural stress are negatively correlated with the inner and outer diameters of the fastening nut. The optimal solution of r1 is determined to be in the interval [a1, c1]. Let b1 = c1, and update the optimization interval of r1 to [8, 11] mm; the optimal solution of r2 is determined to be in the interval [a2, c2]. Let b2 = c2, and update the optimization interval of r2 to [18, 21] mm.
[0073] Repeat the above steps, recalculating the midpoint c and recalculating P each time a and σ a , P c and σ c , P b and σ b, and then adjust the search interval according to the objective function value;
[0074] Then determine whether the termination condition is met. The termination condition is when the number of cycles is ≥ 100, or when it is less than the optimization accuracy, such as 1.0 -3 , terminate the loop;
[0075] Finally, step 150 is executed to determine the optimal size, optimal preload and optimal clamping force of the fastening nut according to the search result. According to one embodiment of the present invention,
[0076] When the cycle ends, the values of the parameters at this time are output, including the nut size (including the values or intervals of r1 and r2), the pressure of the tightening contact surface of the nut, and the maximum stress of the nut structure; when the difference between the upper and lower bounds of the interval of r1 and r2 is less than the preset threshold, any value in the upper or lower bound is output as the corresponding value, without outputting an interval. Otherwise, the interval of r1 and r2 is output.
[0077] According to the output nut size (including r1, r2) and the pressure of the tightening contact surface of the nut, the optimized preload force Foptimization of the bolt is first calculated by the formula:
[0078] F 优化 =S12*P 优化 ;
[0079] S 12 =π*(r2 2 -r1 2 );
[0080] Then, the optimized bolt clamping force Toptim is calculated by the following formula:
[0081] T 优化 =k*d*F 优化 ;
[0082] Among them, T 优化 is the optimized tightening force of the bolt, in Nm; F 优化 is the optimized preload force of the bolt, in N; d is the nominal diameter of the thread, in m; k is the torque coefficient, which is related to the roughness of the nut seat surface and the pitch.
[0083] According to one embodiment of the present invention, when the present invention is cycled 7 times, the difference between the upper and lower limits of the simulated inner diameter interval or the difference between the upper and lower limits of the simulated outer diameter interval is < the optimized accuracy. At this time, the values of r1 and r2 are 9 mm and 22 mm, and the pressure value of the tightening contact surface of the nut and the maximum stress value of the nut structure are 42 MPa and 560 MPa.
[0084] According to the output nut size (including r1 = 9mm, r2 = 22mm) and the compression contact surface pressure of the fastening nut (42MPa), the optimized bolt preload F is first calculated by the formula 优化 :
[0085] F 优化 =S12*P 优化 ; F 优化 The calculated value is 53147N.
[0086] S 12 =π*(r2 2 -r1 2 );
[0087] Then, the optimized bolt clamping force Toptim is calculated by the following formula:
[0088] T 优化 =k*d*F 优化 ; T 优化 The calculation is 79.72
[0089] The excellent effect of the present invention is that in the field of digital design optimization of X-ray tubes and products, the original size design scheme of the product, structural load and other key features are comprehensively considered, and parametric modeling, numerical simulation and other technologies are fully utilized to efficiently, scientifically and accurately realize the size design and optimization of the anode target plate clamping force and the fastening nut. Therefore, the method can greatly improve the structural design efficiency of the anode target plate fastening nut of the X-ray tube, shorten the research and development cycle, and reduce the loosening of the anode target plate or the breakage of the fastening nut.
[0090] The present invention clarifies the initial design preload and nut compression contact area according to the anode target plate contact surface compression design requirements and the initial design size of the fastening nut compression contact surface for the first time; then, with the help of numerical simulation analysis method, an anode target plate bolt preload simulation analysis model is constructed, and the anode target plate bolt compression contact surface pressure simulation analysis is carried out to obtain the compression contact surface pressure and the compression force, and compare them with the design values and the material compressive strength to verify the preload; at the same time, the compression performance of the nut pad is considered during the simulation verification; when the compression force or the compression contact surface pressure does not meet the design requirements, an optimization method is further used to optimize the bolt preload and the fastening nut structural size, and finally the optimal design scheme for the nut structural size and the preload is determined. The anode target fastening nut structural design optimization method proposed in this patent can not only optimize the nut structural dimensions, but also optimize the bolt preload; therefore, this method uses simulation analysis methods to optimize the nut and preload design, which can greatly improve the X-ray tube anode target fastening nut structural design efficiency, shorten the research and development cycle, and reduce the anode target loosening or fastening nut breakage failures, and has great scientific research and engineering application value. The present invention has been verified through simulation analysis and physical tests. The test results show that the anode target fastening nut with optimized dimensions and preload has significantly enhanced contact pressure and preload, and the problems of anode target loosening and nut breakage are significantly improved. The results of some test schemes are shown in Table 2 below:
[0091] Table 2 Test results
[0092]
[0093] It should be noted that the storage medium (computer-readable medium) mentioned above in the present application may be a computer-readable signal medium or a non-transitory computer-readable storage medium or any combination of the above two. The non-transitory computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of non-transitory computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.
[0094] In the present application, a non-transitory computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, apparatus, or device. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a non-transitory computer-readable storage medium, which may send, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (radio frequency), etc., or any suitable combination of the above.
[0095] The computer-readable medium may be included in the electronic device, or may exist independently without being incorporated into the electronic device.
[0096] The above description is only a partial embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.
[0097] In addition, although each operation is described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the application. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.
[0098] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.
Claims
1. A method for designing and optimizing the structure of a fastening nut for an anode target of an X-ray tube, the method comprising the steps of: Obtain the fastening design requirements of the anode target of the X-ray tube, and build a parametric model of the anode target and the fastening nut according to the two-dimensional design information of the fastening gasket, the structural properties of the material at room temperature and high temperature, the thermal properties, and the compression and rebound characteristics of the fastening gasket material in the fastening design requirements; Constructing a simulation analysis model according to the parameterized model of the anode target plate and the fastening nut and the design allowable preload of the bolt; Determining simulation analysis results according to the simulation analysis model, wherein the simulation analysis results include a simulated pressure of a compression contact surface of the fastening nut and a simulated structural stress of the fastening nut; If the simulation analysis result does not meet the fastening design requirements, then setting the simulation variables of the fastening nut according to the parameterized model, including the simulated inner diameter and the simulated outer diameter of the fastening nut, performing simulation variable value search in the simulation intervals of the simulated inner diameter and the simulated outer diameter, and obtaining the value search results; The optimized size, optimized preload force and optimized clamping force of the fastening nut are determined according to the value search results.
2. The method of claim 1, wherein: The fastening design requirements include design allowable pressure and allowable maximum structural stress, and the method further includes: If the simulated pressure of the clamping contact surface is less than the design allowable pressure and / or the simulated structural stress of the fastening nut is greater than the maximum allowable structural stress, it is determined that the simulation analysis result does not meet the fastening design requirements.
3. The method according to claim 1 or 2, wherein: The simulation interval includes an initial simulation inner diameter interval [a1, b1] and an initial simulation outer diameter interval [a2, b2]. The simulation variable value search is performed in the simulation intervals of the simulation inner diameter and the simulation outer diameter, and the value search results obtained include: Determine an initial simulation inner diameter interval median c1 and an initial simulation outer diameter interval median c2 according to the initial simulation inner diameter interval and the initial simulation outer diameter interval; According to the simulation values of the inner and outer diameters of the fastening nut are a1 and a2, c1 and c2, b1 and b2, the corresponding simulated pressure of the clamping contact surface and the simulated structural stress of the fastening nut are determined as follows: P a and σ a , P c and σ c , P b and σ b ; According to P a and σ a , P c and σ c , P b and σ b Determine the correlation between the simulated pressure and simulated structural stress and the inner and outer diameters of the fastening nut.
4. The method of claim 3, wherein: According to P a and σ a , P c and σ c , P b and σ b Determine the correlation between the simulated pressure and the simulated structural stress and the inner and outer diameters of the fastening nut including: If P c >P a , P c <P b , while σ c >σ a , σ c <σ b , it is determined that the simulated pressure and simulated structural stress are positively correlated with the inner and outer diameters of the fastening nut; If P c <P a and / or σ c <σ a , it is determined that the simulated pressure and simulated structural stress are negatively correlated with the inner and outer diameters of the fastening nut.
5. The method of claim 4, further comprising: If the simulated pressure and the simulated structural stress are positively correlated with the inner and outer diameters of the fastening nut, the second simulated inner diameter interval [b1, c1] is determined according to the median value c1 of the initial simulated inner diameter interval and the upper limit value b1 of the initial simulated inner diameter interval; The second simulation outer diameter interval [b2, c2] is determined according to the median value c2 of the initial simulation outer diameter interval and the upper limit value b2 of the initial simulation inner diameter interval.
6. The method of claim 4, further comprising: If the simulated pressure and the simulated structural stress are negatively correlated with the inner and outer diameters of the fastening nut, the second simulated inner diameter interval [a1, c1] is determined according to the lower limit value a1 of the initial simulated inner diameter interval and the median value c1 of the initial simulated inner diameter interval; The lower limit value a1 of the initial simulation outer diameter interval and the median value c2 of the initial simulation outer diameter interval determine the second simulation outer diameter interval [a2, c2].
7. The method according to claim 5 or 6, further comprising: Determine a second simulation inner diameter interval median and a second simulation outer diameter interval median according to the second simulation inner diameter interval and the second simulation outer diameter interval; Re-determine the correlation between the simulated pressure and the simulated structural stress and the inner and outer diameters of the fastening nut according to the second simulated inner diameter interval, the median of the second simulated inner diameter interval, the second simulated outer diameter interval, and the median of the second simulated outer diameter interval; The simulation inner diameter interval and the simulation outer diameter interval are re-determined according to the correlation between the simulation pressure and the simulation structural stress and the inner and outer diameters of the fastening nut until the condition for stopping the simulation variable value search is reached.
8. The method of claim 7, wherein: The step of determining the optimized preload force comprises: Determine the area of the optimized pressing contact surface according to the optimized size of the fastening nut; The optimized preload force is determined according to the area of the optimized pressing contact surface and the optimized pressure.
9. A computing device comprising: one or more processors; Memory; as well as One or more devices comprising instructions for performing any of the methods according to claims 1 to 8.
10. A computer-readable storage medium storing one or more programs, the one or more programs comprising instructions which, when executed by a computing device, cause the computing device to perform any of the methods according to claims 1 to 8.