1. A design method of an electric contact joint is characterized by comprising the following steps:

s1, placing the standard electric contact joint in a typical service environment H₁Lower service time T₀Then, detecting and acquiring a characteristic parameter set A of the oxide layer on the surface of the standard electrical contact joint₁；

Placing a standard electrical contact joint in a typical service environment H₂Lower service time T₀Then, detecting the characteristic parameter set A of the oxide layer on the surface of the standard electric contact joint₂；

……

Placing a standard electrical contact joint in a typical service environment H_MLower service time T₀Then, detecting the characteristic parameter set A of the oxide layer on the surface of the standard electric contact joint_M；

Wherein, the elements of the characteristic parameter set comprise a plurality of elements of the thickness, the composition and the surface roughness of an oxide layer; the service life of the standard electric contact joint in a typical service environment is not shorter than the service time T₀The electrical contact terminal of (1); m is a positive integer not less than 2;

s2, establishing a corresponding relation database between the typical service environment and the characteristic parameter set according to the data obtained in S1;

s3, designing N types of electric contact connectors, wherein the N types of electric contact connectors are made of different materials;

wherein N is a positive integer not less than 3;

s4, preparing L types of electric contact joints with different initial surface roughness aiming at each type of the N types of electric contact joints, and obtaining N x L types of electric contact joints;

wherein L is a positive integer not less than 3;

s5, preparing at least M electrical contact terminals for each of the N x L electrical contact terminals;

respectively preparing oxidation layers with the characteristic parameter sets under the corresponding typical service environments on the surfaces of the M electrical contact terminals according to the corresponding relation database between the typical service environments and the characteristic parameter sets to obtain at least N x L x M electrical contact terminals;

s6, conducting an electric contact friction test on the at least N X L M electric contact joints respectively, and recording the friction times when the contact resistance exceeds a preset failure value;

s7, checking whether the types of the electric contact joints meeting the service life requirement under the target typical service environment exist according to the test result of S6, and if more than 1 type exists, selecting the globally optimal type of the cost and the service life by using a particle swarm optimization algorithm; and if not, repeating S2-S6 until the electric contact joint meeting the service life requirement under the target typical service environment is designed.

2. The design method according to claim 1, wherein in S1, the parameter indexes of the typical service environment include several of temperature, humidity, air quality parameters, and annual rainfall; further, the temperature is an annual average temperature, the air quality parameter is a PM2.5 content, and the humidity is an annual average relative humidity.

3. The design method of claim 1, wherein in S1, the standard electrical contact is made of a copper alloy.

4. The design method according to claim 1, wherein in S3, the material of the N-type electrical contact terminal is copper alloy; further, the copper alloy with different formulas of N types in total is obtained by adopting a hyper-Latin matrix.

5. The design method of claim 1, wherein in S3, the N-type electrical contact terminal is one that has been screened for structural strength, processability, and electrical conductivity.

6. The designing method as set forth in claim 1, wherein the electrical contact terminal is ground using sand paper to obtain the electrical contact terminal having a target initial surface roughness in S4.

7. The design method according to claim 1, wherein in S5, for each of the N x L kinds of electrical contact terminals, N x M electrical contact terminals are prepared; and n is a natural number not less than 1.

8. The design method of claim 1, wherein in S5, the method for preparing the oxide layer with the corresponding characteristic parameter set under typical service environment is as follows: oxidizing the surface of the electrical contact joint, and controlling the thickness of an oxide layer by controlling the temperature and time of the oxidation treatment; further controlling the composition of the oxide layer by regulating and controlling the oxidizing atmosphere; and after the oxidation treatment, polishing the oxide layer to control the surface roughness of the oxide layer.

9. The designing method according to claim 1, wherein in S6, an electric contact friction test is performed by an electric contact fretting friction tester, and the number of times of friction when the contact resistance exceeds a preset failure value is recorded.

10. The design method of claim 1, wherein in step S7, if there is no electric contact terminal type meeting the service life requirement of the target typical service environment, the material of the electric contact terminal is redesigned or the service life expectancy is reduced, and steps S2-S6 are repeated until an electric contact terminal meeting the service life requirement of the target typical service environment is designed.

Background

Electrical contacts are an essential component of all power electronics, and their reliability is of paramount importance. Due to the differences of load types, contact areas and environmental conditions, the materials are various, so that extremely complex physical and chemical processes exist in the electrical contact. The basic requirements of the electrical contact material are: (1) good electric and heat conduction performance; (2) low contact resistance and temperature rise; (3) resistance to fusion welding and to environmental agents.

Before or during use, the electrical contact (electrical contact terminal) is not an absolutely clean polished surface in most cases due to the complicated storage method or working environment. The surface of the contact is often covered with a certain amount of oxide layer and its roughness is large. Therefore, it is necessary to design the electrical contact structure in consideration of the performance influence of the surface oxide layer on the pre-designed structure.

Meanwhile, because the electronic equipment is difficult to avoid various severe environments such as external vibration, magnetostriction, pulse and the like in the use process, the relative motion with extremely small relative displacement amplitude, namely 'micro motion' is inevitable at the connection part of the electronic components. The damage of the micro-motion phenomenon to the electrical contact performance of the electrical components is extremely fatal.

Part of special electric contact equipment needs complicated working environment in service, and a certain amount of oxide can exist on the surface in service. The oxide will directly affect the electrical contact performance of the electrical contact material in the required working environment, and deteriorate the signal transmission stability during the operation of the electronic device. If the material is selected without consideration of the effects of material oxidation, direct selection of the material for the electrical contact structure by only intrinsic parameters such as hardness and conductivity of the material may suffer from unpredictable degradation problems.

Disclosure of Invention

In view of the defects of the prior art, the present invention provides a design method of an electrical contact terminal, so as to obtain a design scheme of an electrical contact terminal suitable for a service environment and having a stable conductive function within a target service life, and solve the problem of failure of the electrical contact terminal caused by different surface roughness and oxide layers of the electrical contact terminal.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a design method of an electric contact joint comprises the following steps:

s1, placing the standard electric contact joint in a typical service environment H₁Lower service time T₀Then, detecting and acquiring a characteristic parameter set A of the oxide layer on the surface of the standard electrical contact joint₁；

Placing a standard electrical contact joint in a typical service environment H₂Lower service time T₀Then, detecting the characteristic parameter set A of the oxide layer on the surface of the standard electric contact joint₂；

……

Placing a standard electrical contact joint in a typical service environment H_MLower service time T₀Then, detecting the characteristic parameter set A of the oxide layer on the surface of the standard electric contact joint_M；

Wherein, the elements of the characteristic parameter set comprise a plurality of elements of the thickness, the composition and the surface roughness of an oxide layer; the service life of the standard electric contact joint in a typical service environment is not shorter than the service time T₀The electrical contact terminal of (1); m is a positive integer not less than 2;

s2, establishing a corresponding relation database between the typical service environment and the characteristic parameter set according to the data obtained in S1;

s3, designing N types of electric contact connectors, wherein the N types of electric contact connectors are made of different materials;

wherein N is a positive integer not less than 3;

s4, preparing L types of electric contact joints with different initial surface roughness aiming at each type of the N types of electric contact joints, and obtaining N x L types of electric contact joints;

wherein L is a positive integer not less than 3;

s5, preparing at least M electrical contact terminals for each of the N x L electrical contact terminals;

respectively preparing oxidation layers with the characteristic parameter sets under the corresponding typical service environments on the surfaces of the M electrical contact terminals according to the corresponding relation database between the typical service environments and the characteristic parameter sets to obtain at least N x L x M electrical contact terminals;

s6, conducting an electric contact friction test on the at least N X L M electric contact joints respectively, and recording the friction times when the contact resistance exceeds a preset failure value;

s7, checking whether the types of the electric contact joints meeting the service life requirement under the target typical service environment exist according to the test result of S6, and if more than 1 type exists, selecting the globally optimal type of the cost and the service life by using a particle swarm optimization algorithm; and if not, repeating S2-S6 until the electric contact joint meeting the service life requirement under the target typical service environment is designed.

Further, in S1, the parameter indexes of the typical service environment include several of temperature, humidity, air quality parameters, and annual rainfall; further, the temperature is an annual average temperature, the air quality parameter is a PM2.5 content, and the humidity is an annual average relative humidity.

Further, in S1, the standard electrical contact is made of a copper alloy.

Further, the service life of the standard electric contact joint in a typical service environment is not shorter than the service time T₀The number of effective switching times is not less than P times; m is a positive integer not less than 2; p is the service time T of the standard electric contact joint in a typical service environment₀In this case, the minimum value of the effective switching times, P is a positive integer, and further P is 200-500.

Further, in S3, the material of the N-type electrical contact terminal is a copper alloy; further, the copper alloy with different N types of formulas is obtained by adopting a super Latin matrix. Optionally, the copper alloy is the same series of copper alloys (the same element composition but different element mixture ratio) or different series of copper alloys (both the element composition and the element mixture ratio are different).

Further, the copper alloy is H62 brass alloy. The H62 brass alloy has the following element composition: 60-64% of Cu; fe0.008-0.012%; pb 0.06-0.10%; 0.13 to 0.17 percent of P; 0.003 to 0.007 percent of S; 0.001 to 0.003 percent of Bi; the balance of Zn (each percentage is mass percent).

Further, in S3, the N-type electrical contact terminal is an electrical contact terminal that has been screened to meet structural strength design requirements, processability requirements, and conductivity requirements.

Further, in S4, the electrical contact terminal is ground with sandpaper to obtain an electrical contact terminal having a target initial surface roughness. For example, the electrical contact terminals may be sanded with different types of sandpaper to provide electrical contact terminals having different surface roughnesses.

Further, in S5, for each of the N × L electrical contact terminals, N × M electrical contact terminals are prepared; and n is a natural number not less than 1. Namely, n electric contact joints are respectively prepared aiming at each of M typical service environments, and when n is more than or equal to 2, a plurality of parallel electric contact joints exist.

Further, in S5, the method for preparing the oxide layer having the characteristic parameter set under the corresponding typical service environment is as follows: oxidizing the surface of the electrical contact joint, and controlling the thickness of an oxide layer by controlling the temperature and time of the oxidation treatment; further controlling the composition of the oxide layer by regulating and controlling the oxidizing atmosphere; and after the oxidation treatment, polishing the oxide layer to control the surface roughness of the oxide layer.

Further, in S6, an electric contact friction test is performed by an electric contact fretting friction tester, and the number of times of friction when the contact resistance exceeds a preset failure value is recorded.

Further, in S6, during the electrical contact friction test, the test environment was kept in conformity with each typical use environment.

Further, in S7, if there is no electric contact terminal type meeting the service life requirement in the target typical service environment, redesigning the material of the electric contact terminal or reducing the service life expectancy, and repeating S2-S6 until an electric contact terminal meeting the service life requirement in the target typical service environment is designed.

The invention designs the electric contact joint considering the influence of the oxide layer, so that the electric contact joint has a stable electric conduction function in a preset use environment and service life.

Further, the electrical contact terminal is an electrical contact terminal for a rail transit vehicle.

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

the method can effectively help designers to evaluate the influence of typical service environment and an oxidation layer in the early stage, screens out the process design parameters of the material and the surface roughness of the electric contact joint meeting the requirements of various typical service environments and service lives by changing the roughness of the electric contact surface and the material composition design of the electric contact joint and by means of a simulation test method, avoids the failure problem in the service cycle, is beneficial to obtaining more and more excellent electric contact joint design schemes, and has engineering practical value.

Drawings

FIG. 1 is a graph of the surface roughness of electrical contact joints of different initial roughness after different oxidation treatments.

FIG. 2 is a graph of the mean contact resistance of electrical contact joints of different initial roughness after different oxidation treatments.

Detailed Description

The present invention will be described in detail with reference to examples. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

Example 1

This embodiment takes an electrical contact of an electronic product made of a common copper alloy material as an example, and further describes a typical service environment H in detail₁The design method of the lower electric contact joint specifically comprises the following steps:

and S0, establishing a typical service environment database of the electric contact joint, wherein M typical service environments are available, and M is 3. The parameter indexes of the typical service environment comprise temperature, humidity, air quality parameters and annual rainfall; the temperature is an annual average temperature, the air quality parameter is PM2.5 content, and the humidity is annual average relative humidity, which is specifically shown in Table 1.

TABLE 1 typical service Environment database

S1, placing the standard electric contact joint in a typical service environment H₁Lower garmentService time T₀(T₀3 months), detecting and acquiring a characteristic parameter set A of the oxide layer on the surface of the standard electric contact joint₁；

Placing a standard electrical contact joint in a typical service environment H₂Lower service time T₀Then, detecting the characteristic parameter set A of the oxide layer on the surface of the standard electric contact joint₂；

Placing a standard electrical contact joint in a typical service environment H₃Lower service time T₀Then, detecting the characteristic parameter set A of the oxide layer on the surface of the standard electric contact joint₃；

Wherein, the elements of the characteristic parameter set comprise a plurality of elements of the thickness, the composition and the surface roughness of an oxide layer; the service life of the standard electric contact joint in a typical service environment is not shorter than the service time T₀And the number of effective switching times is not less than P times (P is 300 times); p is the service time T of the standard electric contact joint in a typical service environment₀The minimum value of the number of effective switching times is obtained, and P is a positive integer;

s2, establishing a corresponding relation database between the typical service environment and the characteristic parameter set according to the data obtained in S1, wherein the corresponding relation database is specifically shown in Table 2;

TABLE 2 database of correspondences between typical service environments and feature parameter sets

S3, designing N types of electric contact connectors, wherein the N types of electric contact connectors are made of different materials; the N-type electrical contact joint is made of copper alloy in the same series; adopting a super Latin matrix, and performing discrete value distribution on each alloy within a reasonable proportion range to obtain copper alloys with the same N element compositions and different element proportions; the material of the N-type electric contact joint and the standard electric contact joint are copper alloys in the same series; wherein N is 2;

s4, preparing L types of electric contact joints with different initial surface roughness aiming at each type of the N types of electric contact joints, and obtaining N x L types of electric contact joints;

wherein L ═ 4;

s5, preparing M ═ 3 electrical contact terminals for each of the N × L electrical contact terminals;

respectively preparing oxidation layers with the characteristic parameter sets under the corresponding typical service environments on the surfaces of the M electrical contact terminals according to the corresponding relation database between the typical service environments and the characteristic parameter sets to obtain at least N x L x M electrical contact terminals;

s6, performing an electrical contact friction test on each of the at least N × L × M electrical contact terminals, and recording the number of times of friction when the average contact resistance exceeds a preset failure value (1000M Ω), as shown in table 3;

TABLE 3 conditions of the electric contact Friction test

S7, checking whether the types of the electric contact joints meeting the service life requirement under the target typical service environment H1 exist according to the test result of S6, if 6 types exist, selecting the globally optimal type of the cost and the service life by using a particle swarm algorithm, wherein the globally optimal type for the typical service environment H1 in the table 3 is H₁-N1-L3, i.e. the material and initial surface roughness of the electrical contact joint can be designed with the initial surface roughness indicated by N1 class H62 brass alloy and L3; and if not, repeating S2-S6 until the electric contact joint meeting the service life requirement under the target typical service environment H1 is designed.

At S3, there is an electrical contact terminal among the N-type electrical contact terminals that satisfies structural strength design requirements, workability requirements, and electrical conductivity requirements.

At S4, the electrical contact is sanded with sandpaper to obtain an electrical contact having a target initial surface roughness.

In S5, the method for preparing the oxide layer having the characteristic parameter set under the corresponding typical service environment is as follows: placing the electric contact joint in a sintering furnace for oxidation treatment, and controlling the thickness of an oxidation layer by controlling the temperature and time of the oxidation treatment; further controlling the composition of the oxide layer by regulating and controlling the oxidizing atmosphere, such as increasing the air quality pollutant components in the target service environment in the sintering furnace and/or regulating and controlling the concentration of the air quality pollutant components; and after the oxidation treatment, polishing the oxide layer to control the surface roughness of the oxide layer. As shown in fig. 1, the oxidized surface roughnesses formed by performing different oxidation treatments on 4 surface roughnesses of N1 copper alloy were selected from those corresponding to the characteristic parameters of the oxide layer formed in a typical environment.

In S6, performing an electric contact friction test through an electric contact fretting friction tester, and recording the friction times when the contact resistance exceeds a preset failure value;

meanwhile, the test environment is kept in accordance with each typical service environment. As shown in fig. 2, the mean contact resistance of the oxide layers after different heat treatments at different surface roughness of the N1 copper alloy electrical contact joint was monitored in real time for changes in contact resistance in the electrical contact fretting test, and whether the preset failure value (1000m Ω) was exceeded or not was evaluated.

In S7, if the type of the electric contact joint which meets the service life requirement under the target typical service environment H1 does not exist, the material of the electric contact joint is redesigned/selected or the service life expectancy is reduced, and S2-S6 are repeated until the electric contact joint which meets the service life requirement under the target typical service environment H1 is designed.

In S7, the service life in each typical service environment is characterized by the effective switching times of the electrical contact terminal in the service life cycle.

In S7, the particle swarm optimization takes two variables of cost and service life as optimization targets, takes the minimum value of service life (10 years, the switching frequency is 1.08 ten thousand times) as a constraint variable, and takes the material and the surface roughness of the electric contact joint as multi-input variables to perform global optimization calculation.

The foregoing examples are set forth to illustrate the present invention more clearly and are not to be construed as limiting the scope of the invention, which is defined in the appended claims to which the invention pertains, as modified in all equivalent forms, by those skilled in the art after reading the present invention.