Microswitch corrosion and electric stress application test performance test method

Abstract

The invention belongs to the technical field of microswitch testing, and provides a microswitch corrosion and electric stress application test performance testing method, which comprises the following steps: S1, pretreatment; s2, carrying out an acid salt spray corrosion test; s3, carrying out a damp heat test; s4, performing a second conversion action test on the microswitch under the conversion test electric load; s5, the steps S2, S3 and S4 are cycled for multiple times, and the test cycle times are adjusted according to the type of the microswitch to be tested; and S6, testing whether the contact rebound time of the microswitch is qualified or not. Through a cyclic combination test of acid salt mist-damp heat-electric stress conversion action, the method is close to an actual service environment within the life period of the microswitch, the influence of corrosion and electric stress superimposed effect on the microswitch can be truly reflected, the exposure efficiency of a weak link of the microswitch is effectively improved, and the reliability of the microswitch is improved. And a test basis and a test means are provided for the corrosion environment resistance of the microswitch.

Description

Technical Field

[0001] The invention belongs to the technical field of micro switch testing, and in particular relates to a micro switch corrosion and electrical stress application test performance testing method. Background Art

[0002] Micro switches are widely used in aviation, aerospace, shipbuilding, weapons and other equipment fields. Moreover, micro switches need to face external corrosive environments when used with equipment, which makes the outer surface and internal precision components of micro switch products susceptible to corrosion, reducing the product's ability to withstand environmental use and even causing product failure or malfunction.

[0003] Currently, the primary evaluation of micro switches' suitability for corrosion environments is based on passing salt spray, damp heat, and mold tests. Passing these tests is considered to meet the requirements for corrosion resistance. However, even though micro switches pass these tests in the laboratory, they often experience failures during field use. This is because laboratory testing only serves to expose product weaknesses and does not provide a comprehensive assessment of the product's adaptability to actual service environments. Consequently, significant differences exist between individual laboratory environmental tests and actual field service environments.

[0004] Furthermore, during their service life, micro switches must repeatedly achieve precise, live switching operations. The electrical load test method specified in the standard places greater emphasis on assessing product lifespan. Numerous studies have shown that corrosion and electrical stress have a cumulative effect. While electrical stress can remove corrosion products from the surface of internal contacts, reducing contact resistance, arcing caused by electrical stress increases the roughness of the contact surface, prompting the initiation and rapid progression of corrosion on the switch's internal contacts.

[0005] Existing testing methods for micro switches lack real-world simulations, and environmental testing methods don't account for the switching action of the micro switch's electrical load. This results in a lack of laboratory testing methods that simulate actual product usage. Therefore, a performance testing method for micro switches undergoing corrosion and electrical stress testing is necessary. Summary of the Invention

[0006] In response to the problems existing in the prior art, the present invention provides a method for testing the corrosion and electrical stress application performance of a micro switch. Through a cyclic combination test of acid salt spray-humid heat-electrical stress conversion actions, the method is close to the actual service environment during the life of the micro switch, and can truly reflect the influence of the superposition effect of corrosion and electrical stress on the micro switch, effectively improving the efficiency of exposing the weak links of the micro switch, and providing a test basis and testing means for the corrosion environment resistance of the micro switch.

[0007] The present invention provides a micro switch corrosion and electrical stress application test performance testing method, which includes the following steps:

[0008] S1. Preprocessing: The DC regulated power supply outputs an electric load on the micro switch, and the micro switch is tested for the first switching action. The micro switch contact bounce time is used to determine whether it is in normal working condition. If the bounce time is greater than a set threshold, the micro switch is replaced. If the bounce time is less than or equal to the set threshold, step S2 is executed.

[0009] S2. Conduct acid salt spray corrosion test:

[0010] S21, preparing an acidic salt solution by adding sulfuric acid to a 5% neutral sodium chloride solution for acidification, and detecting the pH value of the sedimentation solution at 35° C. to be within the set range of 3.5±0.5;

[0011] S22. The salt spray box is tested for 16 hours to 24 hours without load. Maintain stable test conditions. Place the micro switch in the shielding box and then put the whole thing into the salt spray box. Keep the micro switch in the salt spray box at 35℃ for 2 hours.

[0012] S23, turn on the automatic spray device and set the continuous spray time to 24 hours;

[0013] S24, after spraying, open the door of the salt spray box, keep the micro switch ventilated and dry at room temperature for 24 hours, during which time, the salt spray deposition rate is detected within the set range of 1 ~ 3mL / (80cm 2 h) and the pH value of the sedimentation solution is within the set range of 3.5±0.5;

[0014] S25, repeat steps S23 and S24, so that the acid salt spray test spray duration is 48 hours, the drying stage duration is 48 hours, and the overall acid salt spray test duration is 96 hours;

[0015] S3. Conduct damp heat test:

[0016] S31. Place the micro switch in a shielded box and place the entire unit in a damp heat chamber at 60°C and 95% relative humidity for 48 hours.

[0017] S32. After the damp heat test, remove the micro switch and place it in a drying oven at 40°C for 4 hours until the micro switch is dried.

[0018] S4. Perform a second switching action test on the micro switch under the switching test electrical load;

[0019] S5, repeat steps S2, S3 and S4 multiple times, and adjust the number of test cycles according to the type of micro switch to be tested;

[0020] S6. Test the contact bounce time of the micro switch. Perform the contact bounce time test under standard electrical load and under actual load respectively. Judge whether the micro switch is qualified by the contact bounce time. If the contact bounce time is less than or equal to the set threshold, the micro switch is qualified; otherwise, the micro switch fails.

[0021] In a preferred embodiment, the shielding box used for the micro switch has through holes with a diameter of 1 cm distributed around it, and there are multiple through holes, with a spacing of 2 cm between the through holes.

[0022] Preferably, the number of first switching actions of the micro switch is set to 10 times, 50 times or 100 times.

[0023] Preferably, the number of second switching actions of the micro switch is set to 50 times, 100 times, 200 times or 500 times.

[0024] Preferably, in step S6, the threshold value of the bounce time of the micro switch is set to 2 ms.

[0025] Preferably, the conversion test electric load output by the DC regulated power supply in step S1 is a voltage of 28 VDC and a current of 0.6 A.

[0026] Preferably, in step S6, the first contact bounce test is performed under the conditions of a standard electrical load voltage of 22 VDC and a current of 3.2 mA, and the second contact bounce test is performed under the conditions of an actual electrical load voltage of 28 VDC and a current of 70 mA.

[0027] Preferably, in step S6, the switch button terminal is repeatedly and periodically pressed in a direction parallel to the movement direction of the micro switch button terminal, the bounce time is displayed on the oscilloscope monitoring interface, and the entire process from the first closure of the internal switch contacts to stable contact is recorded. The rate of cyclic pressing of the switch button terminal is set to 0.025mm±0.01mm times / second, and the maximum value of 10 consecutive contact bounce times is taken as the contact bounce time of the micro switch.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. The present invention's microswitch corrosion and electrical stress performance testing method, through a cyclic combination test of acid salt spray-humid heat-electrical stress conversion action, provides more comprehensive and realistic feedback on the superimposed effects of corrosion and electrical stress on the microswitch under actual service conditions. This allows the microswitch test environment to be aligned with actual working conditions, and can expose failure phenomena and failure modes that often occur under actual service conditions close to those in the field.

[0030] 2. The corrosion and electrical stress application test performance testing method of the micro switch of the present invention, and the superposition effect of corrosion and electrical stress, are beneficial to the development and improvement of micro switches, saving the later maintenance cost of micro switch products, improving the authenticity of micro switch life, and extending the service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of the micro switch corrosion and electrical stress application test performance testing method of the present invention;

[0032] Figure 2 Schematic diagram of the contact bounce test circuit 1 of the present invention;

[0033] Figure 3 Schematic diagram of contact bounce test circuit 2 in the present invention;

[0034] Figure 4a to Figure 4c This is a test result diagram of an embodiment of the micro switch corrosion and electrical stress application test performance testing method of the present invention. DETAILED DESCRIPTION

[0035] To fully describe the technical content, structural features, objectives and effects of the present invention, the following is a detailed description with reference to the accompanying drawings.

[0036] The micro switch corrosion and electrical stress application test performance test method of the present invention is as follows: Figure 1 As shown, it includes the following steps:

[0037] S1. Preprocessing: The DC regulated power supply outputs an electric load on the micro switch, and the micro switch is tested for the first switching action. The contact bounce time of the micro switch is used to determine whether it is in a normal working state. If the bounce time is greater than the set threshold, the micro switch is replaced. If the bounce time is less than or equal to the set threshold, step S2 is executed.

[0038] In a preferred embodiment, the conversion test electric load output by the DC regulated power supply in step S1 is 28VDC, 0.6A, and the number of first conversion actions of the micro switch is set to 10 times, 50 times or 100 times.

[0039] S2. Conduct acid salt spray corrosion test:

[0040] S21. Prepare the acidic salt solution by adding sulfuric acid to a 5% neutral sodium chloride solution for acidification until the pH value of the sedimentation solution is within the set range of 3.5±0.5 at 35°C.

[0041] S22. The salt spray box is tested at no-load for 16 hours to 24 hours, and stable test conditions are maintained. The micro switch is placed in a shielding box and then placed in the salt spray box as a whole. The micro switch is kept in a salt spray box at 35°C for 2 hours.

[0042] S23. Turn on the automatic spray device and set the continuous spray time to 24 hours.

[0043] S24, after spraying, open the door of the salt spray box, keep the micro switch ventilated and dry at room temperature for 24 hours, during which time, the salt spray deposition rate is detected within the set range of 1 ~ 3mL / (80cm 2 h) and the pH value of the sedimentation solution is within the set range of 3.5±0.5.

[0044] S25. Repeat steps S23 and S24 to make the acid salt spray test spray duration 48 hours, the drying stage duration 48 hours, and the overall acid salt spray test duration 96 hours.

[0045] S3. Conduct damp heat test:

[0046] S31. Place the micro switch in a shielded box and place the entire box in a damp heat box at a temperature of 60°C and a relative humidity of 95%. The test lasts for 48 hours.

[0047] S32. After the damp heat test is completed, take out the micro switch and place it in a drying oven at 40°C for 4 hours until the micro switch is dried.

[0048] S4. Perform a second switching action test on the micro switch under the switching test electrical load.

[0049] The second switching action times of the micro switch are set to 50 times, 100 times, 200 times or 500 times.

[0050] S5. Repeat steps S2, S3 and S4 multiple times, and adjust the number of test cycles according to the type of micro switch to be tested.

[0051] S6. There are two ways to test the contact bounce time of the micro switch. The first way is to test the contact bounce time under a standard electrical load. The second way is to test the contact bounce time under an actual load. The contact bounce time is used to determine whether the micro switch is qualified. If the contact bounce time is less than or equal to the set threshold, the micro switch is qualified, otherwise the micro switch fails.

[0052] In a preferred embodiment, in step S6, the first contact bounce test is performed under the standard electrical load conditions of 22 VDC and 3.2 mA, and the second contact bounce test is performed under the actual electrical load conditions of 28 VDC and 70 mA, and the set threshold of the bounce time of the micro switch is 2 ms.

[0053] The shielding box used for the micro switch is distributed with through holes with a diameter of 1 cm around it, and there are multiple through holes, with a spacing of 2 cm between the through holes.

[0054] like Figure 2 As shown, the DC voltage source outputs 22V±2V. The circuit features two 6.8kΩ resistors connected in series, with the oscilloscope connected in parallel to the first 6.8kΩ resistor. When testing a microswitch, the microswitch is connected in parallel with the second 6.8kΩ resistor. Because the microswitch's internal resistance is in the milliohm range, when the microswitch is connected to the circuit, the current no longer flows through the second 6.8kΩ resistor but flows almost entirely through the microswitch. Therefore, the current flowing through the microswitch is calculated to be 22V / 6.8kΩ = 3.2mA.

[0055] like Figure 3 As shown in the figure, according to the microswitch product specifications, the actual operating load conditions for the microswitch are 28VDC and 70mA. Specifically, the DC voltage source output voltage is 28V, two 400Ω resistors are connected in series in the circuit, and the oscilloscope is connected in parallel with the first 400Ω resistor. When testing the microswitch, the microswitch is connected in parallel with the second 400Ω resistor. Since the microswitch's internal resistance is in the milliΩ range, when the microswitch is connected to the circuit, the current no longer flows through the second 400Ω resistor, but instead flows almost entirely through the microswitch. Therefore, the current flowing through the microswitch is calculated to be 28V / 400Ω = 70mA.

[0056] Further integration Figure 3 The DC voltage source output is adjusted to 28V. Ohm's law is used to calculate the circuit resistance under the actual electrical load of the microswitch. The actual circuit load is adjusted to 400Ω in series with 400Ω. The oscilloscope and microswitch are each connected in parallel with two 400Ω load resistors. When using an oscilloscope to test the microswitch contact bounce time, press the microswitch to close its normally open contacts. When closed, due to the low contact resistance of the microswitch, which is only in the ohm range, the current flows essentially entirely through the microswitch's internal circuit. At this point, the voltage across the switch is 28VDC and the current is 70mA. The oscilloscope test waveform shows the bounce waveform during the microswitch contact operation.

[0057] The following is a further description of the micro switch corrosion and electrical stress test performance testing method of the present invention in conjunction with the embodiments:

[0058] The mission characteristics of micro switches during their life cycle are in a cyclical working state, such as aircraft parked on the ground and in the air, cars parked in a garage and running on the road, ships docked and sailing at sea. Micro switches are cyclically in a stopped and working state. In the stopped state, the equipment will face corrosive environments such as high humidity and high salt spray. In the working state, the micro switch is in a live switching action.

[0059] Taking a certain type of WWK series micro switch as the object, we first conducted product appearance inspection and basic electrical performance tests, and the results were all qualified. The average initial value of the product contact resistance was 6.373mΩ, the average initial value of the contact bounce time was 1.2ms, and the threshold was 2ms.

[0060] Five micro switches of this model were preconditioned and subjected to 200 switching cycles under a switching test load, with the switches pressed 200 times. A 20cm*20cm*20cm transparent acrylic box was designed with 1cm diameter circular holes distributed around the perimeter, arranged in four rows and six columns on each side, with a spacing of approximately 2cm between each hole. The micro switches were placed within the acrylic box and tested according to the following test profile, as shown in Figure 4. A total of four test cycles were performed.

[0061] After the test, the test data results are as follows:

[0062]

[0063]

[0064] The test results of the contact bounce time of the test piece are as follows: Figures 4a to 4c shown.

[0065] Figure 4a This is a typical test output graph of the normal micro switch contact bounce time, which is the test result of the normal contact bounce time of the micro switch after leaving the factory and before testing.

[0066] Figure 4b and Figure 4c After undergoing four cycles of corrosion-electrical stress combination tests, the contact bounce time of the microswitch increased significantly, directly from the initial value of about 80us to about 800us, a full increase of 10 times. This is basically similar to the conclusion that after a microswitch fails in actual use, the re-measured contact bounce time is 8 times the initial value.

[0067] The contact bounce time of three of the five micro switches did not meet the requirements, and the test waveforms were distorted. 0.6A and 50 switching operations had a certain improvement on the contact bounce time. However, judging from the specific waveforms, the contact bounce burr peaks were significantly deteriorated compared to the initial state. Moreover, from repeated tests, if the combined corrosion and electrical stress application tests are continued, the probability of micro switch failure detection can be effectively improved.

[0068] The micro switch corrosion and electrical stress application test performance testing method of the present invention, through a cyclic combination test of acid salt spray-humid heat-electrical stress conversion action, is close to the actual service environment during the service life of the micro switch. It can truly reflect the influence of the micro switch on the superposition effect of corrosion and electrical stress, effectively improve the efficiency of exposing the weak links of the micro switch, and provide a test basis and testing means for the corrosion environment resistance of the micro switch.

[0069] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A micro switch corrosion and electrical stress test performance test method, characterized in that: It includes the following steps: S1, pre-processing: the DC regulated power supply outputs an electric load on the micro switch, performs the first switching action test on the micro switch to be tested, and judges whether it is in a normal working state by the contact bounce time of the micro switch. If the bounce time is greater than the set threshold, replace the micro switch; if the bounce time is less than or equal to the set threshold, execute step S2; S2. Conduct acid salt spray corrosion test: S21, preparing the acidic salt solution, adding sulfuric acid to a 5% neutral sodium chloride solution for acidification, until the pH value of the sedimentation solution is detected to be within the set range of 3.5±0.5 at 35°C; S22. The salt spray box is tested for 16h to 24h without load, and stable test conditions are maintained. The micro switch is placed in the shielding box and then placed in the salt spray box as a whole. The micro switch is kept in the salt spray box at 35℃ for 2h; S23, turn on the automatic spray device and set the continuous spray time to 24 hours; S24, after spraying, open the cover of the salt spray box, keep the micro switch ventilated and dry at room temperature for 24 hours, during which time, the salt spray deposition rate is detected within the set range of 1~3mL / (80cm 2 h) and the pH value of the sedimentation solution is within the set range of 3.5±0.5; S25, repeating steps S23 and S24, so that the acid salt spray test spray duration is 48 hours, the drying stage duration is 48 hours, and the overall acid salt spray test duration is 96 hours; S3. Conduct damp heat test: S31. Place the micro switch in a shielded box and place the whole in a damp heat box at a temperature of 60°C and a relative humidity of 95%. The test lasts for 48 hours. S32. After the damp heat test, take out the micro switch and place it in a drying oven at 40°C for 4 hours until the micro switch is dried; S4. Perform a second switching action test on the micro switch under the switching test electrical load; S5, repeat steps S2, S3 and S4 multiple times, and adjust the number of test cycles according to the type of micro switch to be tested; S6. Test the contact bounce time of the micro switch. Perform the contact bounce time test under standard electrical load and under actual load respectively. Judge whether the micro switch is qualified by the contact bounce time. If the contact bounce time is less than or equal to the set threshold, the micro switch is qualified, otherwise the micro switch fails.

2. The micro switch corrosion and electrical stress application test performance testing method according to claim 1 is characterized in that: The shielding box used for the micro switch is provided with through holes with a diameter of 1 cm distributed around it, and a plurality of through holes are provided, and the spacing between the through holes is 2 cm.

3. The micro switch corrosion and electrical stress application test performance testing method according to claim 1 is characterized in that: The number of first switching actions of the micro switch can be set to 10, 50 or 100 times.

4. The micro switch corrosion and electrical stress application test performance testing method according to claim 1 is characterized in that: The second switching action times of the micro switch are set to 50 times, 100 times, 200 times or 500 times.

5. The micro switch corrosion and electrical stress application test performance testing method according to claim 1 is characterized in that: In step S6, the threshold value of the bounce time of the micro switch is set to 2 ms.

6. The micro switch corrosion and electrical stress application test performance testing method according to claim 1 is characterized in that: In step S1, the conversion test electric load output by the DC regulated power supply is a voltage of 28VDC and a current of 0.6A.

7. The micro switch corrosion and electrical stress application test performance testing method according to claim 1 is characterized in that: In step S6, a first contact bounce test is performed under the conditions of a standard electrical load voltage of 22 VDC and a current of 3.2 mA, and a second contact bounce test is performed under the conditions of an actual electrical load voltage of 28 VDC and a current of 70 mA.

8. The micro switch corrosion and electrical stress application test performance testing method according to claim 1 is characterized in that: In step S6, the switch button terminal is repeatedly and periodically pressed in a direction parallel to the movement direction of the micro switch button terminal. The bounce time is displayed on the oscilloscope monitoring interface, and the entire process from the first closure of the internal contacts of the switch to stable contact is recorded. The rate of cyclic pressing of the switch button terminal is set to 0.025mm±0.01mm times / second, and the maximum value of 10 consecutive contact bounce times is taken as the contact bounce time of the micro switch.

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