Method for measuring static contact resistance of railway signal relay contact

Abstract

The invention relates to the technical field of railway signal relays, and discloses a railway signal relay contact static contact resistance measuring method, which comprises the following steps: selecting a measuring probe with a corresponding shape according to the type of a relay contact to be tested; according to the model of the relay contact, selecting one or more measurement modes from a fixed pressure and fixed current mode, a fixed pressure and current change mode, a fixed current and pressure change mode and a matrix test mode as target measurement modes; in the target measurement mode, a four-terminal resistance measurement method is adopted to measure the static contact resistance of the railway signal relay contact, so that the applied current passes through the measurement probe and the relay contact which are in contact with each other, and the static contact resistance of the railway signal relay contact is measured according to the applied current and the voltage difference between the two sides of the contact position of the measurement probe and the relay contact. The contact resistance between the measuring probe and the relay contact is obtained, and the precision of the measuring result is high.

Description

Technical Field

[0001] The invention relates to the technical field of railway signal relays, and in particular to a method for measuring the static contact resistance of a railway signal relay contact. Background Art

[0002] There are many types of contacts involved in railway signal relays. Although their shape characteristics vary greatly, their preparation processes are very similar. That is, they go through smelting, atomization, extrusion, wire drawing, cold rolling, stress relief, cleaning, polishing, and re-cleaning to finally form the contact products used on relays.

[0003] At present, usually only vernier calipers are used to measure the appearance size parameters of contact nail heads, nail feet, etc., or the surface defects or burrs are observed by naked eyes. There are very few advanced equipment such as scanning electron microscopes to observe and analyze the surface morphology and composition of contacts. There are very few measurements of contact resistance of contact material products. Even if there are, multimeter measurement methods are usually used. This measurement method is not flexible enough and has low measurement accuracy. Summary of the invention

[0004] The object of the present invention is to provide a method for measuring the static contact resistance of a railway signal relay contact, which can improve the measurement accuracy of the static contact resistance of the relay contact.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a method for measuring the static contact resistance of a railway signal relay contact, comprising the following steps:

[0006] According to the type of relay contact to be tested, select a measuring probe of corresponding shape;

[0007] According to the model of the relay contact, one or more measurement modes are selected as target measurement modes from a fixed pressure and fixed current mode, a fixed pressure and current variation mode, a fixed current and pressure variation mode, and a matrix test mode;

[0008] Among them, in the fixed pressure and fixed current mode, the contact pressure and applied current between the measuring probe and the relay contact are fixed; in the fixed pressure and current change mode, the contact pressure is fixed and the applied current is not fixed; in the current and pressure change mode, the contact pressure is not fixed and the applied current is fixed; in the matrix test mode, the contact pressure and applied current are fixed, and the measurement area is the enclosed area formed along the X and Y directions of the measuring probe;

[0009] In the target measurement mode, the static contact resistance of the railway signal relay contacts is measured by the four-terminal resistance measurement method, so that the applied current passes through the measuring probe and the relay contact that are in contact with each other, and the contact resistance between the measuring probe and the relay contact is obtained based on the applied current and the voltage difference generated on both sides of the contact point between the measuring probe and the relay contact.

[0010] In some optional embodiments, the step of selecting a measuring probe of a corresponding shape according to the type of the relay contact to be tested includes:

[0011] If the relay contact is a common static contact, select a test probe with an arched shape;

[0012] If the relay contact is a normal moving contact, select a cylindrical test probe;

[0013] If the relay contact is a reinforced moving contact or a stationary contact, select a curved cylindrical test probe.

[0014] In some optional embodiments, according to the model of the relay contact, one or more measurement modes are selected as the target measurement mode from a fixed pressure and fixed current mode, a fixed pressure and current change mode, a fixed current and pressure change mode, and a matrix test mode, including:

[0015] If the relay contacts are those of the railway signal AX series relay, select the fixed pressure and fixed current mode as the target measurement mode;

[0016] If the relay contacts are other types of contacts other than the railway signal AX series relays, select the fixed pressure and fixed current mode, the fixed pressure and current variation mode, the fixed current and pressure variation mode, and the matrix test mode as the target measurement mode.

[0017] In some optional embodiments, before measuring the static contact resistance of the railway signal relay contact using the four-terminal resistance measurement method, the method further includes:

[0018] Determine the number of times the relay contacts are tested according to the model of the relay contacts.

[0019] In some optional embodiments, the method of measuring the static contact resistance of the railway signal relay contact using a four-terminal resistance measurement method includes:

[0020] If the relay contact is a railway signal AX series relay contact, the static contact resistance of the railway signal relay contact is measured using a four-terminal resistance measurement method with an applied current of 10mA to 1000mA, an applied voltage of 20mV to 200mV, and a contact pressure of 10mN to 1000mN as measurement conditions.

[0021] In some optional embodiments, the method of measuring the static contact resistance of the railway signal relay contact using a four-terminal resistance measurement method includes:

[0022] After aligning the measuring probe with the middle position of the relay contact, the static contact resistance of the railway signal relay contact is measured using the four-terminal resistance measurement method.

[0023] In some optional embodiments, after obtaining the contact resistance between the measuring probe and the relay contact, the method further includes:

[0024] If the static contact resistance of the relay contact is less than or equal to 2mΩ, the relay contact is considered qualified;

[0025] If the static contact resistance of the relay contact is greater than 2mΩ and less than or equal to 5mΩ, re-measure the static contact resistance of the relay contact;

[0026] If the static contact resistance of the relay contact is greater than 10mΩ, the relay contact is judged to be unqualified.

[0027] In some optional embodiments, before measuring the static contact resistance of the railway signal relay contact using the four-terminal resistance measurement method, the method further includes:

[0028] Put the relay contact into any card slot in a pre-obtained card tray, wherein the card tray includes a plurality of card slots having the same size as the relay contact;

[0029] Make sure the relay contacts are fixed in the slots and in reliable contact.

[0030] The method for measuring the static contact resistance of railway signal relay contacts provided by the present invention has at least the following beneficial effects:

[0031] The present invention not only selects a measuring probe of a corresponding shape for the type of relay contact to be tested, but also selects a corresponding measuring mode for the type of relay contact, and then uses a four-terminal resistance measurement method to measure the static contact resistance of the railway signal relay contact in the selected measuring mode, so that the applied current passes through the measuring probe and the relay contact that are in contact with each other, and according to the applied current and the voltage difference generated on both sides of the contact point between the measuring probe and the relay contact, the contact resistance between the relay contact and the selected measuring probe is measured, and the measurement result of the static contact resistance of the relay contact can be obtained. A more suitable measuring tool and measuring method are selected for different types of relay contacts, which can effectively improve the measurement accuracy of the static contact resistance of the railway signal relay contact, thereby ensuring the quality and reliability of the relay product. In addition, the measuring modes are diverse, and a measuring mode suitable for the relay contact can be selected according to the model of the relay contact to be tested, and the measuring method is flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] One or more embodiments are exemplarily described by the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments.

[0033] Figure 1 It is a flow chart of a method for measuring the static contact resistance of a railway signal relay contact provided according to an embodiment of the present invention;

[0034] FIG. 2( a ) is a specific schematic diagram of an arched circular test probe provided according to an embodiment of the present invention;

[0035] FIG2( b ) is a specific schematic diagram of a cylindrical test probe provided according to an embodiment of the present invention;

[0036] FIG2( c ) is a detailed schematic diagram of a curved cylindrical test probe provided according to an embodiment of the present invention;

[0037] FIG3( a ) is a schematic diagram of calibration of a test voltage provided according to an embodiment of the present invention;

[0038] FIG3( b ) is a schematic diagram of calibration of a test current provided according to an embodiment of the present invention;

[0039] FIG. 3( c ) is a schematic diagram of calibration of a test resistor provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the embodiments of the present invention, many technical details are proposed in order to enable the reader to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined and referenced with each other without contradiction.

[0041] An embodiment of the present invention relates to a method for measuring the static contact resistance of a railway signal relay contact. The implementation details of the method for measuring the static contact resistance of a railway signal relay contact of this embodiment are specifically described below. The following content is only the implementation details provided for ease of understanding and is not necessary for implementing this solution.

[0042] The specific process of the method for measuring the static contact resistance of the railway signal relay contact of this embodiment can be as follows: Figure 1 As shown, including:

[0043] Step 101: Select a measuring probe of a corresponding shape according to the type of the relay contact to be tested.

[0044] Specifically, if the relay contact is an ordinary static contact, that is, a cylindrical contact with a diameter of 1.6 mm and a length of 5 mm, also called a silver wire contact, then an arched circular test probe is selected, and the specific schematic diagram of the arched circular test probe is shown in Figure 2(a), wherein 1 represents the arched circular measuring probe, 2 represents the fixing device of the silver wire contact, 3 represents the installation position of the arched circular measuring probe, and 4 represents the silver wire contact.

[0045] If the relay contact is an ordinary moving contact, that is, a hollow cylindrical contact processed from a thin sheet of metal, a cylindrical test probe is selected, and the specific schematic diagram of the cylindrical test probe is shown in Figure 2(b), wherein 1 represents an ordinary moving contact, 2 represents a fixing device for the cylindrical test probe, 3 represents a fixing device for the ordinary moving contact, and 4 represents a cylindrical test probe.

[0046] If the relay contact is a reinforced moving contact or static contact, that is, a rivet-type contact, a curved cylindrical test probe is selected, and the specific schematic diagram of the curved cylindrical test probe is shown in Figure 2(c), wherein 1 represents a fixing device of the curved cylindrical test probe, 2 represents the curved cylindrical test probe, 3 represents a reinforced moving contact or static contact, and 4 represents a fixing device of the reinforced moving contact or static contact.

[0047] Step 102 , according to the model of the relay contact, one or more measurement modes are selected as target measurement modes from a fixed pressure and fixed current mode, a fixed pressure and current variation mode, a fixed current and pressure variation mode, and a matrix test mode.

[0048] Specifically, if the relay contacts are contacts of the railway signal AX series relays, the fixed pressure and fixed current mode is selected as the target measurement mode; if the relay contacts are contacts of other models other than the railway signal AX series relays, the fixed pressure and fixed current mode, the fixed pressure and current change mode, the fixed current and pressure change mode and the matrix test mode are selected as the target measurement modes.

[0049] Among them, in the fixed pressure and fixed current mode, the contact pressure and applied current between the measuring probe and the relay contact are fixed, that is, the contact pressure is fixed to a specific value, generally based on the lower limit of the contact pressure value specified for the railway signal relay as a fixed value, and the applied current is fixed to a specific value, generally based on the load value of the railway signal relay in the specified electrical life test as a fixed value, and then under the conditions of fixed pressure and fixed applied current, the static contact resistance of the relay contact is tested.

[0050] In the fixed pressure and current variation mode, the contact pressure is fixed and the applied current is not fixed, that is, the contact pressure is fixed to a specific value, generally based on the lower limit of the contact pressure value specified for the railway signal relay, and the applied current is set to different values, generally based on the actual current passing through the contact of this model in different railway signal circuits, and then the static contact resistance of the relay contact is tested under the conditions of fixed pressure and variable applied current.

[0051] In the current and pressure change mode, the contact pressure is not fixed and the applied current is fixed, that is, the applied current is fixed to a specific value, generally based on the load value of the railway signal relay in the specified electrical life test. Different pressure values ​​are applied, generally set according to the adjustment range value of the railway signal relay, and then the static contact resistance of the relay contact is tested under the conditions of fixed applied current and pressure change.

[0052] In the matrix test mode, the contact pressure and applied current are fixed, and the measurement area is the enclosed area formed along the X and Y directions of the measuring probe, that is, within the enclosed area in the X and Y directions of the measuring probe, the static contact resistance of the relay contact is measured under the conditions of fixed contact pressure and fixed current.

[0053] Step 103, in the target measurement mode, the static contact resistance of the railway signal relay contact is measured by a four-terminal resistance measurement method, so that the applied current passes through the measuring probe and the relay contact that are in contact with each other, and the contact resistance between the measuring probe and the relay contact is obtained based on the applied current and the voltage difference generated on both sides of the contact point between the measuring probe and the relay contact.

[0054] Among them, the measurement principle of the four-terminal resistance measurement method is: when a stable current Ic passes through the measuring probe and relay contacts that are in contact with each other, a contact potential difference Vc will be generated on both sides of the contact. As long as Ic and Vc are accurately measured, the contact resistance Rc between the measuring probe and the relay contact can be calculated.

[0055] In one example, when measuring the contact resistance between the relay contact and the measuring probe, it is first necessary to determine the measurement conditions of the static contact resistance of the relay contact, which are divided into electrical conditions and mechanical conditions. Among them, the electrical condition is that the measurement is carried out under direct current conditions, and the measurement conditions used are: a) the measurement current is 10mA~1000mA; b) the measurement voltage is 20mV~200mV; the mechanical condition is: the measurement is carried out under the preset contact pressure conditions, and the contact pressure to be used is 10mN~1000mN. Therefore, this embodiment specifically uses the measurement current of 10mA~1000mA, the measurement voltage of 20mV~200mV and the contact pressure of 10mN~1000mN as the measurement conditions to measure the contact resistance between the relay contact and the measuring probe.

[0056] In one example, before measuring the contact resistance between a relay contact and a measuring probe, the test voltage, test current, test resistance, and test pressure of the measuring system should first be calibrated.

[0057] The test voltage calibration is as follows: a) the calibration instrument probe should be reliably connected to the measuring port of the measuring device, as shown in Figure 3(a); b) the test voltage value set by the measuring device host computer should be consistent with the display of the measuring device slave computer and the calibration instrument; c) the minimum scale value of the test voltage is 1mV. The test current calibration is as follows: a) the calibration instrument probe should be reliably connected to the measuring port of the measuring device, as shown in Figure 3(b); b) the test current value set by the measuring device host computer should be consistent with the display of the measuring calibration instrument; c) the minimum scale value of the test current is 1mA. The test resistance calibration is as follows: a) The measuring device port should be reliably connected to the corresponding terminals of the corresponding standard resistors C1, C2, P1, and P2, as shown in Figure 3(c); b) The upper computer of the measuring device sets the test current value to be output to the input terminal of the standard resistor, and the lower computer of the measuring device collects the voltage value at the terminals P1 and P2 of the standard resistor, uploads it to the upper computer, and converts it to display the resistance value on the upper computer; c) The resistance value displayed on the upper computer of the measuring device should be consistent with the actual resistance value of the standard resistor; d) The test resistance accuracy is not less than 0.02%. The test pressure calibration is as follows: a) The calibration instrument for the test pressure should be placed horizontally on the table of the measuring device; b) The test pressure value is set on the upper computer of the measuring device, and the test probe is adjusted so that the probe tests the center position of the instrument for the test pressure; c) The minimum scale value of the test resistance is 0.1mΩ.

[0058] Before measuring the contact resistance between the relay contact and the measuring probe, the measuring probe and the test chuck need to be cleaned, including the following cleaning steps: a) For new contacts and probes that have not been used, use non-woven cotton cloth dipped in anhydrous ethanol to lightly wipe their surfaces, and use a deerskin towel to wipe back and forth at least five times to ensure that they are clean. After wiping, the surface to be tested should not be touched by hand to prevent secondary contamination of the contact and probe surfaces; b) For the contacts of the used relay, use an ear cleaning ball to clean their surfaces, and keep the contacts in their original state during the treatment process; c) Use non-woven cotton cloth dipped in anhydrous ethanol to clean each station of the test chuck to ensure that there are no foreign objects in the stations.

[0059] When measuring the contact resistance between the relay contact and the measuring probe, the relay contact needs to be placed in a chuck, which includes multiple slots that are consistent with the size of the relay contact. The relay contact is then placed in any slot in the pre-obtained chuck to ensure that the relay contact is accurately positioned, reliably contacted, and has no offset in each workstation.

[0060] Before measuring the contact resistance between the relay contact and the measuring probe, the parameters must be set according to the following requirements: a) When measuring the railway signal AX series relay contacts, 10 contacts should be randomly selected from a batch of contacts for testing; b) When testing the contacts, the test standard head should be aligned with the middle position of the contact for testing, that is, the measuring probe needs to be aligned with the middle position of the relay contact, and then the contact resistance between the relay contact and the measuring probe should be measured; c) When measuring the railway signal AX series relay contacts, the test should be conducted 10 times under the test conditions of measuring voltage 20mV, measuring current 500mA, and contact pressure 150mN; d) When measuring new models and types of contacts, the open circuit voltage, test current, contact pressure and number of tests can be defined as needed.

[0061] In one example, after obtaining the measurement result of the static contact resistance of the relay contact, if the static contact resistance of the relay contact is less than or equal to 2mΩ, the relay contact is judged to be qualified; if the static contact resistance of the relay contact is greater than 2mΩ and less than or equal to 5mΩ, the static contact resistance of the relay contact is remeasured; if the static contact resistance of the relay contact is greater than 10mΩ, the relay contact is judged to be unqualified. It should be noted that for new models and new types of relay contacts, the measurement results should be statistically analyzed without the above threshold determination.

[0062] In the specific implementation, after measuring the contact resistance between the relay contact and the measuring probe, the following measurement contents should be recorded: a) model, specification size, material brand, status description, etc. of the relay contact; b) material, shape, specification, etc. of the measuring probe; c) pairing condition, contact pressure, measurement voltage, and measurement current; d) measurement results; e) test ambient temperature and humidity; f) influencing conditions that occur during the measurement process; g) measurement date and measurement personnel, and finally a test report is issued based on the above test contents.

[0063] In this embodiment, only for the type of relay contact to be tested, a measuring probe of a corresponding shape is selected for it, and a corresponding measuring mode is selected for it according to the model of the relay contact, and then in the selected measuring mode, a four-terminal resistance measurement method is used to measure the static contact resistance of the railway signal relay contact, so that the applied current passes through the measuring probe and the relay contact that are in contact with each other, and according to the applied current and the voltage difference generated on both sides of the contact between the measuring probe and the relay contact, by measuring the contact resistance between the relay contact and the selected measuring probe, the measurement result of the static contact resistance of the relay contact can be obtained, and more suitable measuring tools and measuring methods are selected for different types of relay contacts, which can effectively improve the measurement accuracy of the static contact resistance of the railway signal relay contact, thereby ensuring the quality and reliability of the relay product. In addition, the measuring modes are diverse, and the measuring mode suitable for the relay contact can be selected according to the model of the relay contact to be tested, and the measuring method is flexible.

[0064] The steps of the above methods are divided only for clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are within the protection scope of the present invention.

[0065] Those skilled in the art can understand that the above embodiments are specific embodiments of the present invention, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the embodiments of the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention, so the protection scope of the embodiments of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for measuring the static contact resistance of a railway signal relay contact, characterized in that: include: According to the type of relay contact to be tested, select a measuring probe of corresponding shape; According to the model of the relay contact, one or more measurement modes are selected as target measurement modes from a fixed pressure and fixed current mode, a fixed pressure and current variation mode, a fixed current and pressure variation mode, and a matrix test mode; Among them, in the fixed pressure and fixed current mode, the contact pressure and applied current between the measuring probe and the relay contact are fixed; in the fixed pressure and current change mode, the contact pressure is fixed and the applied current is not fixed; in the current and pressure change mode, the contact pressure is not fixed and the applied current is fixed; in the matrix test mode, the contact pressure and applied current are fixed, and the measurement area is the enclosed area formed along the X and Y directions of the measuring probe; In the target measurement mode, the static contact resistance of the railway signal relay contacts is measured by the four-terminal resistance measurement method, so that the applied current passes through the measuring probe and the relay contact that are in contact with each other, and the contact resistance between the measuring probe and the relay contact is obtained based on the applied current and the voltage difference generated on both sides of the contact point between the measuring probe and the relay contact.

2. The method for measuring the static contact resistance of railway signal relay contacts according to claim 1, characterized in that: The step of selecting a measuring probe of a corresponding shape according to the type of the relay contact to be tested comprises: If the relay contact is a common static contact, select a test probe with an arched shape; If the relay contact is a normal moving contact, select a cylindrical test probe; If the relay contact is a reinforced moving contact or a stationary contact, select a curved cylindrical test probe.

3. The method for measuring the static contact resistance of railway signal relay contacts according to claim 1, characterized in that: According to the model of the relay contact, one or more measurement modes are selected as the target measurement mode from the fixed pressure and fixed current mode, the fixed pressure and current change mode, the fixed current and pressure change mode and the matrix test mode, including: If the relay contacts are those of the railway signal AX series relay, select the fixed pressure and fixed current mode as the target measurement mode; If the relay contacts are other types of contacts other than the railway signal AX series relays, select the fixed pressure and fixed current mode, the fixed pressure and current variation mode, the fixed current and pressure variation mode, and the matrix test mode as the target measurement mode.

4. The method for measuring the static contact resistance of railway signal relay contacts according to claim 1, characterized in that: Before the four-terminal resistance measurement method is used to measure the static contact resistance of the railway signal relay contact, the method further includes: Determine the number of times the relay contacts are tested according to the model of the relay contacts.

5. The method for measuring the static contact resistance of railway signal relay contacts according to claim 4, characterized in that: The method of measuring the static contact resistance of the railway signal relay contact by using a four-terminal resistance measurement method comprises: If the relay contact is a railway signal AX series relay contact, the static contact resistance of the railway signal relay contact is measured using a four-terminal resistance measurement method with an applied current of 10mA to 1000mA, an applied voltage of 20mV to 200mV, and a contact pressure of 10mN to 1000mN as measurement conditions.

6. The method for measuring the static contact resistance of railway signal relay contacts according to claim 5, characterized in that: The method of measuring the static contact resistance of the railway signal relay contact by using a four-terminal resistance measurement method comprises: After aligning the measuring probe with the middle position of the relay contact, the static contact resistance of the railway signal relay contact is measured using the four-terminal resistance measurement method.

7. The method for measuring the static contact resistance of railway signal relay contacts according to claim 1, characterized in that: After obtaining the contact resistance between the measuring probe and the relay contact, the method further includes: If the static contact resistance of the relay contact is less than or equal to 2mΩ, the relay contact is considered qualified; If the static contact resistance of the relay contact is greater than 2mΩ and less than or equal to 5mΩ, re-measure the static contact resistance of the relay contact; If the static contact resistance of the relay contact is greater than 10mΩ, the relay contact is judged to be unqualified.

8. The method for measuring the static contact resistance of railway signal relay contacts according to claim 1, characterized in that: Before the four-terminal resistance measurement method is used to measure the static contact resistance of the railway signal relay contact, the method further includes: Put the relay contact into any card slot in a pre-obtained card tray, wherein the card tray includes a plurality of card slots having the same size as the relay contact; Make sure the relay contacts are fixed in the slots and in reliable contact.

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