CN115936257A - A method for optimizing key parameters of wire crimping - Google Patents

Abstract

The invention discloses a method for optimizing key parameters of wire crimping, which comprises the following steps: (1) Setting an evaluation index, wherein the evaluation index is the wire grip strength; (2) setting the required variable of wire crimping; selecting a plurality of design variables from the variables; (3) establishing a single-target optimization model function expression; (3) Generating sample points through experiments, and establishing a proxy model according to the initial sample points; the proxy model comprises an objective function and a constraint condition; (4) Calculating the model precision according to the prediction result of the agent model and the combination of experimental data; (5) detecting whether the model precision meets the requirement; (6) And calculating the parameter value combination of all variables corresponding to the maximum value of the objective function, namely the current optimization result. The invention obtains the input-output relation between the crimping process parameter and the evaluation index by establishing the proxy model, and selects a set of proper crimping process parameter to improve the crimping quality.

Description

A method for optimizing key parameters of wire crimping

technical field

The invention relates to the technical field of optimization of key parameters of wire crimping, and more specifically, to a method for optimizing key parameters of wire crimping.

Background technique

Important intersecting and crossing lines refer to transmission lines crossing the above-mentioned railways, expressways, first-class highways, first- and second-class navigable rivers, etc. In the overhead transmission lines in our country, the connection of the wire terminal and the fixing method of the wire in the tension section mostly adopt the tension clamp. The strain clamp is composed of an aluminum tube and a steel anchor. The steel anchor is used to connect and anchor the steel core. The aluminum tube is used to connect the aluminum wire part of the wire. The aluminum tube and the steel anchor are crimped and molded by pressure, so that the wire and the wire The clamps are combined into a whole, which can bear all the tension of the conductor and the lightning conductor, and play the role of flow. Because the tension tube used as the anchor wire bears all the tension of the wire, it faces severe tests under severe weather conditions such as strong winds and severe ice. In view of the fact that many accidents are caused by the unqualified crimping process and the lack of specific optimization of the crimping process parameters, how to improve the crimping quality of the wire and explore the optimization of the key parameters of the crimping to optimize the crimping quality method is important.

At present, the crimping of wires mainly uses compression type strain clamps. The compression type strain clamp is composed of aluminum tube, steel anchor and drainage plate. The wire crimping process involves many crimping process parameters, some of which have a greater impact on crimping quality. The wire crimping process is shown in Figure 1.

There are relatively few previous studies on the relationship between the crimping process parameters and crimping quality of tension clamps and the optimization methods of crimping quality, and there are certain limitations in blindly adopting existing optimization methods.

Based on the results of previous studies, the present invention proposes a new type of optimization method for the crimping quality of conductors of important cross-over lines, that is, kriging optimization algorithm. For the present invention, the crimping process parameter of the strain clamp is the direct factor affecting the crimping quality of the cross-span line wire, so the present invention will determine the parameters that mainly affect the crimping quality of the strain clamp, and select a suitable Evaluation index, through the establishment of a proxy model to obtain the input-output relationship between crimping process parameters and evaluation indicators, and select a set of suitable crimping process parameters to improve crimping quality and ensure crimping is qualified and reliable. Future research will provide some data support.

Contents of the invention

The purpose of the present invention is to provide a method for optimizing key parameters of wire crimping, which can determine the parameters that mainly affect the crimping quality of strain clamps, select appropriate evaluation indicators, and obtain crimping process parameters and evaluation indicators by establishing a proxy model According to the input-output relationship, a set of suitable crimping process parameters is selected based on the best, so as to improve the quality of crimping, ensure the crimping is qualified and reliable, and provide certain data support for future research.

In order to achieve the above purpose, a method for optimizing key parameters of wire crimping is provided, including the following steps:

(1) Evaluation index is set, and described evaluation index is wire grip strength, and wire grip strength is the maximum load that wire and strain clamp can bear when there is no slipping phenomenon;

(2) Set the required variables for wire crimping; and select several design variables from the variables;

(3) The function expression of the single-objective optimization model is established as follows:

In the formula, _x1 and _x2 are the design variables, F is the optimization target of the evaluation index, X _L and X _U are the lower limit value of the design variable and the upper limit value of the design variable respectively;

(4) produce sample point by experiment, set up proxy model according to initial sample point; Described sample point is in the two-dimensional coordinate system, selects a certain different design variable, the parameter value of the certain design variable of change and wire grip force Corresponding point; Described agent model comprises objective function and constraint condition;

(5) Calculate the model accuracy according to the prediction results of the proxy model combined with the experimental data;

(6) Detect whether the accuracy of the model meets the requirements, and if it is satisfied, perform step (7); if not, re-execute step (3);

(7) The combination of parameter values of all variables corresponding to the maximum value of the calculated objective function is the current optimization result.

In particular, the experiment of the step (4) is in accordance with the provisions of the overhead transmission line construction and acceptance specification for the hydraulic connection of the wire and the fittings: the tensile test of the test piece should be carried out before the wiring construction, and the test pieces should not be less than 3 groups. The test holding strength shall not be less than 95% of the designed breaking force of the wire.

In particular, in the step (4), the initial sample point is generated through experiments, and the specific method of establishing the proxy model according to the initial sample point is:

(1) Select computer experimental design methods to generate sample points for design variables;

(2) Use a high-precision analysis model to analyze these sample points to obtain a set of input and output data;

(3) Estimating and training model parameters based on input and output data, using maximum likelihood estimation and cross-validation methods to determine model parameters;

(4) Test and validate the proxy model.

In particular, the verification agent model is verified by simulation.

In particular, the variables include pipe penetration depth, die width, aluminum pipe inner diameter, side-to-side distance, stack die width, and grip value.

In particular, the design variables include the pipe penetration depth and the inner diameter of the aluminum pipe.

In particular, in the step (6), meeting the requirements means that the model accuracy meets an error of less than 5%.

In particular, the agent model is a Kriging agent model.

Working principle of the present invention and beneficial effect are as follows:

The unqualified wire crimping quality is mainly manifested in the following two points:

(1) The depth of the pipe penetration is unqualified: if the depth of the pipe penetration is too small, the contact area between the steel core and the steel pipe will be reduced, and the friction between the two will be further reduced, thereby reducing the grip between the wire and the tension clamp .

(2) Inappropriate selection of the inner diameter of the aluminum tube: The force transmission between the two components at the crimping part actually depends on the friction between the deformed tube and the single wire. As shown in Figure 2, the cross-section of the aluminum tube before compression is a ring, and after compression, the outer side becomes a regular hexagon inscribed in the circle, and the inner diameter of the inner side is also reduced accordingly until it fits the outer surface of the aluminum stranded wire. If the inner diameter of the aluminum tube is too small, the wire is easy to get stuck when passing through the tube. If the inner diameter of the aluminum tube is too large, the crimping will not be true. During the grip test, there will be slippage due to insufficient friction between the crimping tube and the wire . Therefore, the ideal grip force can be obtained by determining the appropriate inner diameter of the aluminum tube, which facilitates the transmission of force between the hardware and the wire.

In summary, the depth of pipe penetration and the inner diameter of the aluminum pipe are the key process parameters of the present invention.

A method for optimizing the key parameters of wire crimping proposed by the present invention, through a large number of research and analysis, aimed at the problems of crimping quality of cross-span line tension clamps, a new optimization method is proposed, with crimping quality as the research In this paper, the important parameters that affect the crimping quality are studied, and the grip force value is proposed as the evaluation index, and the kriging optimization algorithm is used to establish the depth of the pipe penetration, the width of the die, the inner diameter of the aluminum pipe, the distance between the sides, the width of the stack die and The surrogate model of the input-output relationship of the grip value, the Kriging surrogate model established based on the strain clamp crimping tensile test data has higher precision, the method that the present invention adopts can realize under the situation of few samples to strain Clamp crimp quality is optimized. The inner diameter of the aluminum tube and the depth of the tube have a significant impact on the grip strength. The present invention selects a suitable evaluation index, obtains the input-output relationship between the crimping process parameters and the evaluation index by establishing a proxy model, and screens out a set of suitable crimping process parameters to improve the crimping quality and ensure the quality of crimping. Qualified and reliable, providing certain data support for future research.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a wire crimping flowchart in the background technology of the present invention;

Fig. 2 is the sectional view before and after compression of the aluminum tube of content of the present invention;

Fig. 3 is the main flowchart of the optimization method of the embodiment of the present invention;

Fig. 4 is the experimental graph of the inner diameter of the aluminum tube of the embodiment of the present invention;

Fig. 5 is the experimental graph of the penetration depth of the embodiment of the present invention;

Fig. 6 is a curve diagram of the optimization result of the inner diameter of the aluminum tube of the embodiment of the present invention;

FIG. 7 is a load synchronization diagram of an embodiment of the present invention;

Fig. 8 is the total deformation result figure after the simulation of the embodiment of the present invention;

Fig. 9 is the stress diagram of aluminum strand 1 of the embodiment of the present invention;

Fig. 10 is a stress diagram of the steel core 1 of the embodiment of the present invention;

Fig. 11 is the stress diagram of aluminum strand 2 of the embodiment of the present invention;

Fig. 12 is a stress diagram of the steel core 2 of the embodiment of the present invention;

Fig. 13 is a schematic diagram of grip force calculation according to an embodiment of the present invention;

Fig. 14 is a schematic diagram of grip force calculation according to an embodiment of the present invention;

Fig. 15 is a graph showing the optimization results of the pipe penetration depth according to the embodiment of the present invention.

Detailed ways

The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to define the protection scope of the present invention more clearly.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

It should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner" and "outer" are Based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship that the inventive product is usually placed in use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must Having a particular orientation, being constructed and operating in a particular orientation, and therefore not to be construed as limiting the invention. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are absolutely horizontal or overhanging, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", and it does not mean that the structure must be completely horizontal, but can be slightly inclined.

A method for optimizing key parameters of wire crimping according to an embodiment of the present invention includes the following steps:

(1) Set the evaluation index, the evaluation index is the wire holding force, and the wire holding force is the maximum load that the wire and the tension clamp can bear without slippage;

(2) Set the required variables for wire crimping; and select several design variables from the variables; the variables include pipe penetration depth, die width, aluminum pipe inner diameter, side-to-side distance, stack die width and grip value. Design variables include penetration depth, aluminum tube inner diameter.

(3) The function expression of the single-objective optimization model is established as follows:

In the formula, _x1 and _x2 are the design variables, F is the optimization target of the evaluation index, X _L and X _U are the lower limit value of the design variable and the upper limit value of the design variable respectively;

(4) Generate sample points through experiments, and establish a proxy model based on the initial sample points. The proxy model is the Kriging proxy model. The sample point is in the two-dimensional coordinate system, selects a different design variable, and the parameter value of the changed certain design variable corresponds to the point of the wire grip; the proxy model includes an objective function and constraint conditions; the initial sample is generated through experiments Example point, the specific method of establishing a proxy model based on the initial sample point is:

(4-1) Select computer experimental design methods to generate sample points for design variables;

(4-2) Use a high-precision analysis model to analyze these sample points to obtain a set of input and output data;

(4-3) Estimating and training model parameters based on input and output data, using maximum likelihood estimation and cross-validation methods to determine model parameters;

(4-4) Test and validate the proxy model. The verification agent model is verified by simulation.

The experiment is in accordance with the provisions of the overhead transmission line construction and acceptance specification for the hydraulic connection of the wire and the fittings: the tensile test of the specimen should be carried out before the construction of the wire, and the specimen should not be less than 3 groups, and the test holding strength should not be less than the design of the wire. 95% of breaking force.

(5) Calculate the model accuracy according to the prediction results of the proxy model combined with the experimental data;

(6) Detect whether the accuracy of the model meets the requirements, and if yes, execute step (7); if not, re-execute step (3); meeting the requirements means that the accuracy of the model meets the error of less than 5%.

(6) The combination of parameter values of all variables corresponding to the maximum value of the calculated objective function is the current optimization result.

Specifically, change the value levels of the depth of the pipe penetration, the width of the die, and the inner diameter of the aluminum pipe, respectively control the change of one of the parameters, and keep the other two parameters unchanged. According to the national standard, the value range of the pipe penetration depth is 50-100mm, and a value is taken at an interval of 10mm. The 5 test pieces obtained are numbered 1-5 in turn, and the width of the die is 40mm, and the obtained test piece is numbered 6; The range of the inner diameter of the aluminum tube is 30.5mm, 32.5mm, 34.5mm and 36mm, and the obtained 4 test pieces are numbered 7-10. The crimping tensile test was carried out on the wire-clip, and the experimental results of each test piece are shown in Table 1:

Table 1 Crimp tensile test data table

From the experimental data, it can be seen that the grip force of the inner diameter of the aluminum tube and the depth of the pipe penetration have obvious changes under different sizes, and then the experimental curves of the inner diameter of the aluminum tube, the depth of the pipe penetration and the grip force are drawn, as shown in Figure 4 and Figure 5. It can be seen from the figure that the inner diameter of the aluminum tube and the depth of the tube penetration should have their own thresholds.

In order to ascertain the respective thresholds of the inner diameter of the aluminum tube and the penetration depth of the tube, and find the corresponding parameter combination when the grip strength is the best, the kriging surrogate model is used to optimize the above parameters. When the depth of the pipe penetration is 100mm, the width of the die is 60mm, the distance between the sides is 13.96mm, and the width of the stack mold is half of the upper mold, let the inner diameter of the aluminum pipe be changed as a single parameter, and within the range of the experimental interval (28.5, 36), each interval is 0.1 Take a value of mm, normalize the inner diameter of the aluminum tube and the grip force, and then establish the kriging proxy model, and the optimization results are shown in Figure 6.

It can be seen that the fitting curve of the inner diameter of the aluminum tube is relatively accurate, and the highest point of the fitting curve is the optimal point of the grip force when the inner diameter of the aluminum tube changes only, and the grip strength is 108.30kN. The parameter threshold of the inner diameter of the aluminum tube is 34.7mm, and the grip strength at this time is 100.71kN, and the grip strength greater than this threshold will not meet the requirements. The inflection point of the fitting curve occurs when the inner diameter of the aluminum tube is 34.5 mm. Considering that the inner diameter of the aluminum tube is too small and it is easy to get stuck, the inflection point of the fitting curve, that is, the inner diameter of the aluminum tube is 34.5 mm, is selected as the optimization result. The parameter threshold of the inner diameter of the aluminum tube is verified by simulation, which is the same as the simulation method for verifying the experimental data, and the load steps are set as shown in Figure 7.

The number of result points is set to 96, that is, the 24 large intervals of the load step are divided into 96 sub-intervals, and three new result points are added in each large interval, the purpose is to find the exact moment of slippage and facilitate the calculation of grip strength. The total deformation result after simulation is shown in Fig. 8.

The parts where the wires are crimped are named aluminum strand 1 and steel core 1, and the parts outside the crimping area are named aluminum strand 2 and steel core 2. Figures 9 to 12 show the stress conditions of aluminum strand 1, steel core 1, aluminum strand 2, and steel core 2, respectively.

Extract the slip data of all result points, and draw the slip curve as shown in Figure 13.

As shown in Figure 14, the workbench shows that the result points set by the dynamics are located in the load interval and are evenly distributed on the curve. The No. 75 slip point is located in the middle of step 19, which is 90%-95% of the curve midpoint position.

By substituting the time-displacement coordinates of the points corresponding to 90% and 95%, the expression of the curve is obtained as y=2590x+0.07, and substituting the time of No. 75 slip point to obtain the force corresponding to No. 75 slip point The size is 95.9kN, so the grip force obtained by simulation under the parameter threshold of the inner diameter of the aluminum tube is 34.7mm is 95.9KN. Through fitting before, the grip force under the parameter threshold of the inner diameter of the aluminum tube is 34.7mm is 100.71kN. The simulation The error between the two fittings is 4.78%.

In the experiment, the grip strength value when the depth of the pipe is 60mm is relatively abnormal, and there is no sample with the grip strength <= 95% RTS at the depth of the pipe, so the depth of the pipe is 40mm and 60mm for simulation calculation. Because the simulation method of the pipe penetration depth of 40mm and 60mm is completely consistent with the simulation method of the experimental verification and the threshold value verification of the inner diameter parameter of the aluminum pipe, through simulation calculation, it can be obtained in the same way that the grip force corresponding to the pipe penetration depth of 40mm and 60mm is 91.6kN respectively , 107.12kN. When the width of the die is 60mm, the inner diameter of the aluminum tube is 28.5mm, the distance between the sides is 13.96mm, and the width of the stack mold is half of the upper mold, let the depth of the pipe penetration be changed as a single parameter within the range (40-100) at intervals of 1mm Take a value, normalize the depth of the pipe penetration and the grip force, and then establish the kriging proxy model, and the optimization results obtained are shown in Figure 15.

The fitting curve of the pipe penetration depth is also more accurate and follows the trend of the experimental curve as a whole. The highest point of the fitting curve is the optimal point of the grip strength with a single change in the depth of the pipe, and the grip strength is 108.30kN. The inflection point of the fitting curve occurs when the pipe penetration depth is 60mm. The parameter threshold of the pipe penetration depth is 50mm. At this time, the grip strength is 99.5kN. If the grip strength is less than this threshold, the grip strength will not meet the requirements.

Since the depth of the pipe penetration and the inner diameter of the aluminum pipe are independent of each other, based on the above-mentioned experimental and optimized data results, in order to make the aluminum strands through the pipe more convenient in actual engineering while still satisfying a high grip force, the embodiment of the present invention selects the aluminum pipe The inner diameter is 34.5mm, the pipe penetration depth is 100mm, the die width is 60mm, the width across the edge is 13.96mm, and the stack die width is half of the upper die as the optimal parameter combination.

Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, the patent owner can make various deformations or modifications within the scope of the appended claims, as long as they do not exceed the scope of protection described in the claims of the present invention, all should Within the protection scope of the present invention.

Claims (8)

1. A wire crimping key parameter optimization method is characterized by comprising the following steps: the method comprises the following steps:

(1) Setting an evaluation index, wherein the evaluation index is the wire grip, and the wire grip is the maximum load which can be borne when the wire and the tension-resistant wire clamp do not slip;

(2) Setting required variables for wire crimping; selecting a plurality of design variables from the variables;

(3) Establishing a single-target optimization model function expression as shown in the following formula:

find DV＝(x ₁ ，x ₂ ) ^T

in the formula, x ₁ And x ₂ For design variables, F is the optimization goal of the evaluation index, X _L And X _U Respectively a lower limit value of the design variable and an upper limit value of the design variable;

(4) Generating sample points through experiments, and establishing a proxy model according to the initial sample points; the sample point is a point in a two-dimensional coordinate system, a certain different design variable is selected, and the parameter value of the changed certain design variable corresponds to the wire grip strength; the proxy model comprises an objective function and a constraint condition;

(5) Calculating the model precision according to the prediction result of the agent model and the combination of experimental data;

(6) Detecting whether the model precision meets the requirement, and if so, executing the step (7); if not, re-executing the step (3);

(7) And calculating the parameter value combination of all variables corresponding to the maximum value of the objective function, namely the current optimization result.

2. The method for optimizing the key parameters of wire crimping according to claim 1, wherein the method comprises the following steps: the experiment of step (4) is according to the rules of overhead transmission line construction and acceptance criteria to the hydraulic connection of wire and gold utensil: and (3) carrying out a test piece tensile test before stringing construction, wherein the test pieces are not less than 3 groups, and the holding strength of the test is not less than 95% of the designed breaking force of the lead.

3. The method for optimizing key parameters of wire crimping according to claim 1, wherein the method comprises the following steps: in the step (4), initial sample points are generated through experiments, and a specific method for establishing the proxy model according to the initial sample points is as follows:

(1) Selecting a computer experiment design method to generate sample points of design variables;

(2) Analyzing the sample points by using a high-precision analysis model to obtain a group of input and output data;

(3) Estimating and training model parameters based on input and output data, and determining the model parameters by using a maximum likelihood estimation and cross validation method;

(4) The proxy model is tested and validated.

4. The method for optimizing the key parameters of wire crimping according to claim 3, wherein the method comprises the following steps: the verification agent model adopts simulation verification.

5. The method for optimizing key parameters of wire crimping according to claim 1, wherein the method comprises the following steps: the variables include the depth of pipe penetration, the width of the pressing die, the inner diameter of the aluminum pipe, the opposite edge distance, the width of the overlapped die and the holding force value.

6. The method for optimizing key parameters of wire crimping according to claim 1, wherein the method comprises the following steps: the design variables include the depth of penetration and the inner diameter of the aluminum tube.

7. The method for optimizing key parameters of wire crimping according to claim 1, wherein the method comprises the following steps: in the step (6), meeting the requirement means that the model precision meets the error less than 5%.

8. The method for optimizing key parameters of wire crimping according to claim 1, wherein the method comprises the following steps: the agent model is a Kriging agent model.

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