A resistance detection device and method

Abstract

This invention relates to the field of automated production line testing and electrical measurement technology, specifically a resistance detection device and method. It includes a cylinder lifting assembly, dual photoelectric switches, and an outer ring current probe and an inner ring voltage probe sleeved together by independent springs. The device achieves sequential probe contact through cylinder pressing, with the outer ring current probe contacting the object under test first and triggering the photoelectric switch to establish current. The core technology is that when the inner ring voltage probe subsequently contacts the object, the bottom contact slope generates controlled radial sliding under the pressing action, effectively breaking down the surface layer of the object under test. This invention physically decouples current establishment and voltage sampling through mechanical action, eliminating contact uncertainties caused by workpiece tolerances and providing a highly consistent foundation for stable and accurate sampling.

Description

Technical Field

[0001] This invention relates to the field of automated production line testing and electrical measurement technology, specifically to a resistance detection device and method. Background Technology

[0002] In automated production line resistance testing scenarios, measuring equipment needs to acquire electrical performance indicators of the test object at high frequency. The signal acquisition process often uses mechanical probes to press and establish an electrical circuit through direct contact. To measure and calculate electrical parameters, existing solutions generally adopt a single spring probe physical architecture, that is, the probe is driven by a cylinder to directly press the test object, thereby performing test signal acquisition. Although this solution has certain processing capabilities in the testing scenario of conventional workpieces, it is highly dependent on a single pressing action, and the contact pressure is very easy to deviate unexpectedly with changes in workpiece dimensional tolerances, probe wear, and surface adhesion layers. This causes the physical attenuation of contact resistance to exceed the preset time, and the low resistance test results to fluctuate greatly, making it difficult to support the high-frequency measurement cycle requirements of the production line.

[0003] Therefore, how to reduce the uncertainty of mechanical contact state, thereby improving the timeliness and accuracy of resistance measurement output, has become an urgent technical problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a resistance detection device and method. Specifically, the technical solution of the present invention is as follows:

[0005] A resistance detection device, comprising:

[0006] Test base;

[0007] A support column is fixedly connected to the test base at its bottom end and a top plate is fixedly connected to its top end;

[0008] A cylinder is fixedly connected to the top plate, and the piston rod of the cylinder extends vertically downward and is connected to a lifting plate at its end;

[0009] An insulating sleeve is fixedly connected to the lower surface of the lifting plate. A first photoelectric switch and a second photoelectric switch are sequentially arranged on the outer side wall of the insulating sleeve along the vertical direction. The second photoelectric switch is located below the first photoelectric switch.

[0010] The outer ring current probe has an outer cylindrical surface that is clearance-fitted with the inner hole of the insulating sleeve. A first spring is pressed between the top of the outer ring current probe and the inner top surface of the insulating sleeve. A vertical guide groove is formed on the side wall of the insulating sleeve in the vertical direction. A light-shielding plate that extends out of the vertical guide groove is provided on the upper part of the outer side wall of the outer ring current probe.

[0011] The inner ring voltage probe has an outer cylindrical surface that is clearance-fitted with the inner hole of the outer ring current probe. A second spring is pressed between the top of the inner ring voltage probe and the inner top surface of the outer ring current probe. The bottom end face of the inner ring voltage probe is provided with a contact slope.

[0012] In one embodiment, the light-shielding plate is fixedly connected to the upper part of the outer side wall of the outer ring current probe by an interference fit.

[0013] In one embodiment, the inclination angle of the contact bevel at the bottom end face of the inner ring voltage probe is 5°.

[0014] In one embodiment, the outer current probe is a cylindrical structure made of beryllium copper, the inner voltage probe is a cylindrical structure made of tungsten steel, and the insulating sleeve is a hollow cylinder made of polytetrafluoroethylene.

[0015] In one embodiment, the bottom end of the support column is fixedly connected to the test base by bolts, the top end of the support column is fixedly connected to the top plate by welding, and the center hole of the lifting plate is threadedly connected to the end of the piston rod of the cylinder.

[0016] A testing method for a resistance detection device includes:

[0017] S1. Control the cylinder to drive the lifting plate to move downward, thereby causing the insulating sleeve, the outer current probe and the inner voltage probe to descend as a whole;

[0018] S2. The bottom end of the outer ring current probe contacts the surface of the object to be tested. The cylinder continues to descend to compress the first spring. The outer ring current probe slides upward relative to the insulating sleeve and drives the light-shielding plate to move upward to block the first photoelectric switch.

[0019] S3. Obtain the trigger signal of the first photoelectric switch being blocked, control the constant current source to output and inject a constant current into the outer current probe;

[0020] S4. The cylinder continues to descend, and the contact slope of the inner ring voltage probe contacts the surface of the object to be tested and generates a lateral force component under the downward action of the second spring, causing the bottom end of the inner ring voltage probe to slide radially on the surface of the object to be tested.

[0021] S5. As the second spring is further compressed, the light-shielding plate continues to move upward and block the second photoelectric switch, and the reference time point when the second photoelectric switch is blocked is obtained.

[0022] In one embodiment, step S5 is followed by:

[0023] S601. Starting from the reference time point, continuously record the first voltage, the second voltage, and the third voltage at equal time intervals;

[0024] S602. A stable voltage is calculated based on the first voltage, the second voltage, and the third voltage.

[0025] S603. The true resistance of the object under test is calculated by dividing the stable voltage by the constant current.

[0026] In one embodiment, step S602 specifically includes: subtracting the second voltage from the third voltage and squaring the difference to obtain the numerator; summing the first voltage and the third voltage and subtracting twice the second voltage to obtain the denominator; when the absolute value of the denominator is determined to be greater than or equal to a preset effective threshold, dividing the numerator by the denominator to calculate the voltage compensation amount; subtracting the voltage compensation amount from the third voltage to obtain the true voltage drop, and using the true voltage drop as the stable voltage.

[0027] In one embodiment, during step S3, when a constant current is injected into the outer current probe, the inner voltage probe is in an open-circuit state before it comes into contact with the object under test.

[0028] In one embodiment, step S603 is followed by: S701, controlling the cylinder to retract the lifting plate to the initial position; S702, cutting off the constant current source output to complete the test cycle.

[0029] The present invention has the following beneficial effects:

[0030] 1. The present invention provides a resistance detection device, which adopts a structure in which the outer cylindrical surface of the inner ring voltage probe and the inner hole of the outer ring current probe are fitted with a gap, and sequential pressing is achieved with the help of a first spring and a second spring; when the cylinder presses down, the outer ring current probe first contacts the object to be tested and blocks the first photoelectric switch to control the output of the constant current source and inject a constant current into the outer ring current probe; the inner ring voltage probe then contacts, and the contact slope at its bottom end generates a lateral force component under the action of pressing down, so that the bottom end of the inner ring voltage probe produces radial sliding on the surface of the object to be tested, which can effectively break the surface adhesion layer; the device decouples the constant current injection and the recording voltage in mechanical action, eliminates the contact uncertainty caused by the workpiece tolerance of a single probe, and provides a highly consistent physical basis for stable sampling;

[0031] 2. The testing method provided by this invention ensures the uniformity of the mechanical contact state at the sampling starting point by using a reference time point determined by the second photoelectric switch being blocked. Starting from the reference time point, a first voltage, a second voltage, and a third voltage are continuously recorded at equal time intervals. Based on the first voltage, the second voltage, and the third voltage, a stable voltage after removing the transient contact voltage drop is calculated. The stable voltage is then divided by the constant current to obtain the true resistance. This testing method directly eliminates the long delay waiting process of physical attenuation of contact resistance in traditional testing. While eliminating low-resistance test fluctuations, it significantly shortens the time consumption of single-piece testing, meeting the preset measurement cycle requirements of automated production lines. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the device;

[0033] Figure 2 This is a schematic diagram of the insulating sleeve and the first and second photoelectric switches of the device.

[0034] Figure 3 This is a schematic diagram of the internal structure of the probe assembly;

[0035] Figure 4 This is a flowchart of the method of the present invention.

[0036] In the diagram: 1. Test base; 2. Support column; 3. Top plate; 4. Cylinder; 5. Piston rod; 6. Lifting plate; 7. Insulating sleeve; 8. First photoelectric switch; 9. Second photoelectric switch; 10. Outer ring current probe; 11. First spring; 12. Light shield; 13. Inner ring voltage probe; 14. Second spring; 15. Contact slope; 16. Vertical guide groove. Detailed Implementation

[0037] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0038] Example 1:

[0039] like Figures 1 to 3 As shown, a resistance detection device includes:

[0040] Test base 1;

[0041] Support column 2 is fixedly connected to test base 1 at its bottom end and fixedly connected to top plate 3 at its top end;

[0042] Cylinder 4 is fixedly connected to top plate 3; wherein, piston rod 5 of cylinder 4 extends vertically downward and is fixedly connected to lifting plate 6 at its end;

[0043] An insulating sleeve 7 is fixedly connected to the lower surface of the lifting plate 6; wherein, a first photoelectric switch 8 and a second photoelectric switch 9 are sequentially arranged on the outer side wall of the insulating sleeve 7 along the vertical direction, and the second photoelectric switch 9 is located below the first photoelectric switch 8.

[0044] The outer ring current probe 10 has an outer cylindrical surface that is clearance-fitted with the inner hole of the insulating sleeve 7; wherein, a first spring 11 is pressed between the top of the outer ring current probe 10 and the inner top surface of the insulating sleeve 7, and a vertical guide groove 16 is provided on the side wall of the insulating sleeve 7 in the vertical direction, and a light shield 12 is provided on the upper part of the outer side wall of the outer ring current probe 10 that extends out of the vertical guide groove 16.

[0045] The inner ring voltage probe 13 has an outer cylindrical surface that is clearance-fitted with the inner hole of the outer ring current probe 10; wherein, a second spring 14 is pressed between the top of the inner ring voltage probe 13 and the inner top surface of the outer ring current probe 10, and a contact slope 15 is provided on the bottom end face of the inner ring voltage probe 13.

[0046] In existing automated production lines, resistance testing often uses a single spring probe to directly press the object to be tested under the drive of a cylinder 4. The contact pressure is prone to unexpected deviations due to changes in workpiece dimensional tolerances, probe wear, and surface adhesion layers. As a result, the contact resistance still needs to undergo a period of attenuation after pressing before it can stabilize.

[0047] If the process is delayed to wait for stabilization, it will increase the single-piece testing time; if sampling is performed directly at the initial contact stage, the low-resistance test results are prone to fluctuation.

[0048] The resistance detection device provided in this embodiment uses a combination of a coaxial layered probe structure, a dual-spring sequential compression structure, and a dual photoelectric switch physical timing triggering structure to separate current establishment and voltage sampling in mechanical action, and to make the voltage probe form a repeatable small radial slip when in contact, thereby providing a stable physical basis for subsequent voltage decay calculation.

[0049] The test base 1 is used to support the whole machine. It is preferably made of metal plate structure with a thickness of 12mm to 30mm to ensure the rigidity of the whole machine when the cylinder 4 reciprocates. The support column 2 is set to 2 or 4, which are fixedly arranged along the upper surface of the test base 1. The support column 2 and the top plate 3 form a vertical frame to limit the installation height and movement axis of the cylinder 4.

[0050] Cylinder 4 is fixedly connected to top plate 3, piston rod 5 extends vertically downward, and lifting plate 6 is fixed to the end of piston rod 5. The extension and retraction of cylinder 4 is converted into the vertical linear motion of lifting plate 6.

[0051] Cylinder 4 can be a standard pneumatic cylinder 4, and the stroke can be set from 20mm to 80mm according to the height of the object to be measured, the amount of probe compression and the safety margin, and the action speed can be set from 50mm / s to 300mm / s.

[0052] The insulating sleeve 7 is fixedly connected to the lower surface of the lifting plate 6 and is used to provide insulation guidance for the outer ring current probe 10. The insulating sleeve 7 here refers to a hollow component that serves both mechanical guidance and electrical isolation. Its inner hole axis is consistent with the movement axis of the cylinder 4 to ensure that the probe moves in the set direction when it is pressed.

[0053] The first photoelectric switch 8 and the second photoelectric switch 9 are arranged vertically on the outer wall of the insulating sleeve 7, with the second photoelectric switch 9 located below the first photoelectric switch 8. This vertical distribution corresponds to two different displacement positions of the outer ring current probe 10 after it is compressed. By directly converting the displacement threshold into a photoelectric blocking signal, the error caused by relying solely on software timing can be avoided.

[0054] The outer cylindrical surface of the outer current probe 10 is clearance-fitted with the inner hole of the insulating sleeve 7 for sliding vertically within the insulating sleeve 7; here, clearance fit refers to a fit relationship that restricts radial swing while ensuring smooth axial sliding, and preferably the single-sided clearance is 0.01mm to 0.05mm.

[0055] A first spring 11 is pressed between the top of the outer current probe 10 and the inner top surface of the insulating sleeve 7. The first spring 11 provides a downward preload force so that the outer current probe 10 remains extended before contacting the test object and can retract relative to the insulating sleeve 7 after contacting the test object.

[0056] The light-shielding plate 12 is fixed to the upper part of the outer wall of the outer ring current probe 10 and extends through the side wall of the insulating sleeve 7. Since the light-shielding plate 12 moves synchronously with the outer ring current probe 10, the displacement of the outer ring current probe 10 can be directly identified by the state of the light-shielding plate 12 blocking the first photoelectric switch 8 or the second photoelectric switch 9.

[0057] The inner ring voltage probe 13 is disposed in the inner hole of the outer ring current probe 10, and its outer cylindrical surface is clearance-fitted with the inner hole of the outer ring current probe 10; this coaxial sleeve structure constitutes spatial separation of the current channel and the voltage sampling channel; wherein, the outer ring current probe 10 is responsible for establishing the current loop, and the inner ring voltage probe 13 is responsible for acquiring the voltage drop;

[0058] A second spring 14 is pressed between the top of the inner ring voltage probe 13 and the inner top surface of the outer ring current probe 10. The second spring 14 provides an axial downward pressure independent of the first spring 11, so that the inner ring voltage probe 13 continues to complete a secondary contact after the outer ring current probe 10 contacts it. A contact slope 15 is provided on the bottom end face of the inner ring voltage probe 13.

[0059] The contact slope 15 here refers to the working end face that is inclined relative to the vertical end face of the probe axis. When axially pressed, it can generate a tangential component force, causing the probe tip to slip slightly on the surface of the object to be measured.

[0060] The sliding is not actively controlled by an additional drive mechanism, but is a passive movement formed by the axial pressure of the contact slope 15 and the second spring 14. It can break the oxide layer and dust layer and improve the conductivity consistency of the contact interface.

[0061] When the device is working, the cylinder 4 presses down to drive the insulating sleeve 7, the outer current probe 10 and the inner voltage probe 13 to approach the object under test as a whole; the outer current probe 10 contacts the object under test first and retracts relatively; when the light shield 12 reaches the position of the first photoelectric switch 8, it outputs the first trigger signal to establish a constant current.

[0062] After the pressure continues to be applied, the inner ring voltage probe 13 is pressed against the object under the action of the second spring 14, and its contact slope 15 produces micro-scratching. When the light shield 12 continues to move to the position of the second photoelectric switch 9, it outputs a second trigger signal to determine the reference time point for voltage sampling.

[0063] Through the above structural combination, the mechanical contact action, current establishment action and voltage sampling action are all limited by different physical thresholds, which reduces the contact uncertainty caused by direct pressing of a single probe and keeps the deviation of subsequent actual resistance calculation within the set tolerance range.

[0064] The light-shielding plate 12 is fixedly connected to the upper part of the outer side wall of the outer ring current probe 10 by interference fit;

[0065] To ensure a one-to-one correspondence between the displacement signal of the outer current probe 10 and the photoelectric detection signal, this embodiment provides a vertical guide groove 16 on the side wall of the insulating sleeve 7. Here, the vertical guide groove 16 refers to a narrow opening extending along the axial direction of the insulating sleeve 7, the length of which covers the entire effective stroke of the outer current probe 10 and restricts the movement direction of the light shield 12.

[0066] The width of the guide groove is preferably 0.05 mm to 0.20 mm greater than the thickness of the light shield 12 to balance smooth sliding and lateral restraint capability. If the guide groove is too wide, the light shield 12 may swing during reciprocating motion, affecting the consistency of the position of the shielding edge. If the guide groove is too narrow, the light shield 12 may rub against the groove wall and get stuck, affecting the response of the outer ring current probe 10.

[0067] The light shield 12 is fixedly connected to the upper part of the outer wall of the outer ring current probe 10 by an interference fit; here the interference fit means that the actual size of the mounting hole or mounting groove of the light shield 12 is smaller than the size of the corresponding mounting part of the outer ring current probe 10, and a stable connection is formed by press fitting.

[0068] The interference fit can be set from 0.005mm to 0.03mm to ensure that the light shield 12 does not loosen under high-frequency reciprocating conditions. Compared with screw connection or adhesive connection, the interference fit does not increase the number of exposed fasteners, is less likely to produce eccentric mass, and is less likely to change the shielding position due to the aging of the adhesive layer.

[0069] After the light-shielding plate 12 is fixed to the upper part of the outer wall of the outer ring current probe 10, the light-shielding plate 12 and the outer ring current probe 10 move synchronously throughout the entire life cycle, ensuring that the blocking moment recognized by the photoelectric switch directly corresponds to the actual displacement state of the outer ring current probe 10.

[0070] In actual assembly, the insulating sleeve 7 can be slotted after turning or injection molding, and the groove wall of the guide groove is parallel to the axis of the inner hole of the insulating sleeve 7; the light shield 12 can be made of opaque metal sheet or opaque polymer sheet, and the thickness can be set to 0.2mm to 1.0mm.

[0071] When the outer ring current probe 10 is in the freely extended position, the light shield 12 is located below the first photoelectric switch 8 and the second photoelectric switch 9; when the outer ring current probe 10 contacts the object to be tested and retracts, the light shield 12 moves upward along the guide groove and enters the detection area of ​​the two photoelectric switches in sequence.

[0072] Due to the constraint of the guide groove on the light shield 12, the position of the light shield 12 passing through the photoelectric switch beam is stable, which can convert the probe displacement into a digital trigger signal that meets the set displacement accuracy.

[0073] This structure enables the first photoelectric switch 8 to establish a current loop displacement threshold corresponding to the outer ring current probe 10, and enables the second photoelectric switch 9 to reach the set contact pressure displacement threshold corresponding to the inner ring voltage probe 13, thereby improving the consistency of subsequent timing control and sampling timing.

[0074] The inclination angle of the contact slope 15 at the bottom end face of the inner ring voltage probe 13 is set to 5°.

[0075] The contact slope 15 at the bottom end face of the inner ring voltage probe 13 is tilted at an angle of 5° to generate a controlled lateral force under the action of axial clamping force, thereby causing the end of the inner ring voltage probe 13 to produce a small radial slip on the surface of the object to be measured; here, 5° is the angle value of the contact slope 15 relative to the horizontal end face.

[0076] If the angle is less than 2°, the lateral component of the axial pressure decomposition cannot reach the force threshold for stably breaking the surface oxide layer; if the angle is greater than 10°, the radial slip increases, causing the contact position to deviate beyond the set target test area, thereby affecting repeated positioning and aggravating probe wear.

[0077] When the tilt angle is set to 5°, a balance can be achieved between contact stability and scraping effect. In the mechanical action, the outer ring current probe 10 first contacts the object to be tested, and the inner ring voltage probe 13 continues to descend with the lifting plate 6 and is pressed against the object to be tested under the action of the second spring 14. Since the bottom end is a 5° contact slope 15, the reaction force of the object to be tested on the probe end can be decomposed into axial and radial components.

[0078] The axial component is used to compress the second spring 14, and the radial component drives the contact point of the inner ring voltage probe 13 to produce a micro-displacement on the surface of the object to be measured; the amount of micro-displacement is related to the compression of the second spring 14, the angle of the contact slope 15, and the friction conditions of the contact interface.

[0079] Within the commonly used compression range of 0.1 mm to 0.5 mm, a 5° inclined plane can create a surface scraping displacement on the order of micrometers to tens of micrometers. This displacement is sufficient to remove oxide films and dust adhering to the metal surface without causing significant damage to the surface of the test object.

[0080] Specifically, under the ideal rigid body kinematic model that does not consider end elastic deformation, the radial slip can be estimated by multiplying the axial compression of the second spring 14 by the tangent of the inclination angle of the contact slope 15.

[0081] For example, when the cylinder 4 is pressed down, causing the second spring 14 to generate an axial compression of 0.3 mm, the theoretical radial slippage generated by the 5° contact slope 15 is approximately 0.3 mm multiplied by 0.0875, which is 0.026 mm.

[0082] This level of micro-scraping can effectively destroy oxide layers with a thickness of several nanometers to tens of nanometers, while avoiding excessive slippage that could cause the probe to slide out of the test pad area of ​​the test object, thus ensuring the reliability of the contact in terms of physical mechanism.

[0083] Using a 5° contact slope 15 also helps to make the contact resistance decay process exhibit a stable single exponential change trend; the reason is that the probe does not experience random contact jitter in the initial contact stage, but rather undergoes constrained micro-movements in a defined slope direction, and the tiny protrusions on the contact surface gradually enter a stable conductive state under the combined action of pressing and scraping.

[0084] Based on this physical process, multiple voltage values ​​are collected within a short period of time after the second photoelectric switch 9 is triggered, and the stable voltage can be estimated by calculation. Thus, while participating in mechanical film removal, the 5° contact slope 15 ensures the stable attenuation of contact resistance from a physical mechanism, which has a direct effect on shortening the test waiting time.

[0085] The outer ring current probe 10 has a cylindrical structure made of beryllium copper, the inner ring voltage probe 13 has a cylindrical structure made of tungsten steel, and the insulating sleeve 7 has a hollow cylinder made of polytetrafluoroethylene.

[0086] This embodiment limits the material and structural form of key components to take into account conductivity, mechanical durability, insulation performance and processing feasibility; the outer ring current probe 10 adopts a circular tube structure made of beryllium copper; beryllium copper material has conductivity that meets the requirements of constant current injection, elastic recovery capability that meets the preset deformation and wear resistance that meets the service life, and is suitable as a current injection component in high-frequency contact conditions.

[0087] The outer current probe 10 is set as a circular tube structure. On the one hand, an inner hole can be formed in its center to accommodate the inner voltage probe 13 and achieve coaxial arrangement. On the other hand, the wall thickness of the circular tube can be set from 0.3mm to 1.5mm according to the current and structural strength to ensure that the temperature rise is controllable and sufficient rigidity is maintained during constant current injection.

[0088] By using a beryllium copper tube, the outer current probe 10 can form a stable current loop when it comes into contact with the object under test, without significantly increasing the overall motion mass, which is beneficial for high-frequency reciprocating testing.

[0089] The inner ring voltage probe 13 adopts a cylindrical structure made of tungsten steel. The hardness and wear resistance parameters of tungsten steel can meet the requirement of maintaining the stability of the end shape under the continuous micro-scraping condition of the contact slope 15. If the end geometry changes more than the preset deformation threshold during long-term use, the lateral component force and slippage law generated by the slope will drift, affecting the contact repeatability.

[0090] With the adoption of tungsten steel cylindrical structure, the probe tip can maintain the 5° contact slope 15 parameter for a long time, reducing the change of algorithm input conditions caused by wear; the inner ring voltage probe 13 serves as a voltage sampling component, and the current passing through it does not exceed the preset measurement current threshold. Tungsten steel mainly plays the role of shape retention and wear resistance at this position.

[0091] The insulating sleeve 7 is a hollow cylinder made of polytetrafluoroethylene (PTFE). PTFE has insulation resistance that meets the requirements for electrical isolation, a coefficient of friction that meets the requirements for sliding guidance, and chemical stability. It can not only provide electrical isolation for the outer ring current probe 10, but also facilitate the smooth sliding of the outer ring current probe 10 along the inner hole.

[0092] The hollow cylindrical structure forms a guide hole inside that corresponds to the outer cylindrical surface of the outer ring current probe 10, while also facilitating the setting of guide grooves and the installation of photoelectric switches on the side wall; the low friction characteristics of polytetrafluoroethylene material can reduce the resistance during the retraction and reset process of the outer ring current probe 10, and improve the displacement response speed formed by the spring and cylinder 4.

[0093] By combining beryllium copper tubes, tungsten steel cylinders, and polytetrafluoroethylene hollow cylinders, the current injection path, mechanical scraping path, and insulation guiding path are optimized respectively.

[0094] The outer current probe 10 focuses on conductivity and retraction, the inner voltage probe 13 focuses on wear resistance and bevel contact, and the insulating sleeve 7 focuses on guidance and isolation. This combination not only meets the structural assembly requirements, but also provides repeatable mechanical conditions for sequential contact and stable sampling of the dual probes.

[0095] The bottom end of the support column 2 is fixedly connected to the test base 1 by bolts, and the top end of the support column 2 is fixedly connected to the top plate 3 by welding. The center hole of the lifting plate 6 is connected to the end of the piston rod 5 of the cylinder 4 by thread.

[0096] This embodiment limits the overall installation and connection relationship to improve assembly accuracy, structural rigidity and maintenance convenience; the bottom end of the support column 2 is fixedly connected to the test base 1 by bolts;

[0097] The bolt fixing method facilitates leveling and disassembly. During equipment installation, the verticality of the support column 2 can be corrected by adjusting the shims or the flatness of the base, so that the top plate 3 and the test base 1 remain parallel.

[0098] The number of bolts can be 2 to 4 per column, and the bolt specifications can be selected from M6 to M12 according to the load; after adopting this method, the support column 2 can be disassembled and replaced or the height of the whole machine can be adjusted during production line maintenance;

[0099] The top plate 3 is fixedly connected to the top of the support column 2 by welding; the welding connection makes the top plate 3 and the support column 2 form a rigid frame, which is beneficial to withstand the inertial load brought by the high-frequency up and down movement of the cylinder 4 and reduce the micro displacement of the top plate 3 relative to the support column 2.

[0100] If the top plate 3 and the support column 2 are detachably connected, the connection may loosen after long-term reciprocating operation, affecting the consistency between the cylinder 4 axis and the probe axis; by adopting the welding method, the deformation of the mounting surface of the top plate 3 during use can be effectively limited, which helps to maintain the stability of the cylinder 4 mounting posture.

[0101] The center hole of the lifting plate 6 is connected to the end of the piston rod 5 of the cylinder 4 by a thread; the threaded connection facilitates the adjustment of the installation height and axial position of the lifting plate 6, and the initial distance between the lower end of the insulating sleeve 7 and the clamp of the object to be tested can be finely adjusted by screwing in the depth during assembly to adapt to different product heights.

[0102] The thread specifications can be from M8 to M16, and a lock nut can be used to prevent loosening during operation; since the lifting plate 6 is directly connected to the piston rod 5 of the cylinder 4, the axial displacement and thrust output by the cylinder 4 are transmitted to the insulating sleeve 7, the outer ring current probe 10 and the inner ring voltage probe 13 through the lifting plate 6; the coaxial thread connection of the center hole is also conducive to keeping the axis of the moving parts consistent and reducing the off-center load when the probe is pressed.

[0103] The above connection methods work together to form a stable force transmission path from the bottom to the execution end, consisting of the test base 1, support column 2, top plate 3, cylinder 4, and lifting plate 6.

[0104] Bolted connections meet installation and maintenance needs, welded connections improve frame rigidity, and threaded connections meet the needs of height adjustment. The displacement and force transmitted through this path can reliably act on the probe assembly, keeping the photoelectric trigger position, spring compression, and contact pressure within the set range.

[0105] Example 2:

[0106] like Figure 4 As shown, a testing method for a resistance detection device includes:

[0107] Step S1: Control cylinder 4 to drive lifting plate 6 to move downward, causing insulating sleeve 7, outer current probe 10 and inner voltage probe 13 to descend as a whole;

[0108] Step S2: Based on the condition that the bottom end of the outer ring current probe 10 contacts the surface of the object to be tested, control the cylinder 4 to continue to descend to compress the first spring 11, so that the outer ring current probe 10 slides upward relative to the insulating sleeve 7 and drives the light shield 12 to move upward to block the first photoelectric switch 8.

[0109] Step S3: Obtain the trigger signal of the first photoelectric switch 8 being blocked, control the constant current source output and inject a constant current into the outer current probe 10;

[0110] Step S4: Based on the condition that the cylinder 4 continues to descend, the contact slope 15 of the inner ring voltage probe 13 contacts the surface of the object to be tested, and under the downward pressure of the second spring 14, a lateral force component is generated, controlling the bottom end of the inner ring voltage probe 13 to produce radial sliding on the surface of the object to be tested.

[0111] Step S5: Based on the condition of further compression of the second spring 14, the light-shielding plate 12 continues to move upward and block the second photoelectric switch 9, and the characteristic time point when the second photoelectric switch 9 is blocked is recorded as the reference time point.

[0112] This embodiment provides a test method for the above-mentioned resistance detection device, which establishes a repeatable contact sequence through the correspondence between mechanical action and electrical signal control.

[0113] In step S1, the control cylinder 4 drives the lifting plate 6 to move downward, causing the insulating sleeve 7, the outer current probe 10, and the inner voltage probe 13 to descend as a whole. During this stage, the relative positions of the three remain basically unchanged. The outer current probe 10 remains extended under the action of the first spring 11, and the inner voltage probe 13 also remains extended relative to the outer current probe 10 under the action of the second spring 14. The downward speed of the cylinder 4 can be set to 80mm / s to 200mm / s to meet the production cycle requirements of approaching the test object, while avoiding high-speed impact that could cause a rebound.

[0114] In step S2, after the bottom end of the outer current probe 10 contacts the surface of the object to be tested, the object to be tested applies an upward reaction force to the outer current probe 10; as the cylinder 4 continues to descend, the insulating sleeve 7 continues to descend with the lifting plate 6, while the outer current probe 10 slides upward relative to the insulating sleeve 7 due to the obstruction of the object to be tested, and the first spring 11 is compressed.

[0115] The light-shielding plate 12, which is fixedly connected to the outer ring current probe 10, moves upward synchronously and blocks the first photoelectric switch 8. This action means that the outer ring current probe 10 has formed mechanical contact with the object to be tested and has reached the set minimum clamping displacement. By establishing the triggering condition on the actual displacement of the probe, rather than on the theoretical stroke of the cylinder 4, the influence of workpiece size tolerance on the triggering time can be reduced.

[0116] The minimum clamping displacement here refers to the axial retraction of the outer ring current probe 10 from its free extension position to the position where the first photoelectric switch 8 is blocked, representing the minimum contact clamping state required before the current path is established.

[0117] The displacement threshold can be determined by the installation height of the first photoelectric switch 8, the initial position of the light shield 12, and the free extension length of the outer ring current probe 10. During assembly, the outer ring current probe 10 can be in a free state first, and then the position of the first photoelectric switch 8 can be adjusted so that the upper edge of the light shield 12 enters the beam area when the outer ring current probe 10 retracts a predetermined distance.

[0118] The role of this threshold in the control process is to limit the start-up timing of the constant current source. Only after the outer current probe 10 reaches the predetermined contact displacement is it allowed to proceed to step S3.

[0119] In step S3, the trigger signal of the first photoelectric switch 8 being blocked is obtained, and the constant current source is controlled to output and inject a constant current into the outer current probe 10. Here, the constant current source refers to a power supply module that maintains a stable output current within a set range. The output current can be set from 10mA to 5A according to the resistance value of the object under test.

[0120] After the outer current probe 10 contacts the object under test, the current loop is established, and the constant current source injects test current into the object under test. Since the inner voltage probe 13 has not yet formed a stable contact with the object under test at this time, the voltage measurement branch does not participate in the conduction. Therefore, the current establishment action and the voltage measurement action can be separated to reduce the impact of contact transient on sampling.

[0121] The preferred trigger signal here is the edge signal when the first photoelectric switch 8 switches from the unshielded state to the shielded state. After receiving the edge signal, the controller enables the constant current source and starts recording the subsequent timing.

[0122] To avoid repeated triggering due to photoelectric jitter, a continuous hold judgment can be set in the control program. For example, the occlusion state must be considered a valid trigger after it lasts for more than a preset confirmation time. The preset confirmation time can be set to 0.05ms to 2ms.

[0123] The confirmation duration is used to filter out the instantaneous jitter when the edge of the light shield 12 passes through the light beam. Its source can be preset according to the response time of the photoelectric switch, the movement speed of the cylinder 4 and the sampling period of the controller. In terms of data flow and interaction, the digital level signals output by the first photoelectric switch 8 and the second photoelectric switch 9 are connected to the hardware interrupt pin or high-speed digital input port of the controller through the opto-isolation module.

[0124] When using hardware interrupt mode, the light-shielding plate 12 blocks the edge signal generated by the photoelectric switch, which directly triggers the highest priority interrupt service subroutine of the controller. The controller sends a digital high-level command to the enable control terminal of the constant current source within a microsecond delay, completing the data flow from mechanical displacement signal to electrical drive command.

[0125] This ensures strict synchronization between the current injection action and the actual physical displacement of the probe; at the same time, the trigger signal of the second photoelectric switch 9 also records the current microsecond-level timestamp through the hardware timer capture function. This timestamp is stored in the designated memory address of the controller as a reference time point for subsequent voltage sampling tasks to read and align, thereby clarifying the processing path of data from acquisition, transmission to application between modules.

[0126] In step S4, the cylinder 4 continues to descend, and the contact slope 15 of the inner ring voltage probe 13 contacts the surface of the object to be tested; as the second spring 14 is compressed, the contact slope 15 converts the axial pressure into an axial clamping component and a lateral force component; the lateral force component drives the bottom end of the inner ring voltage probe 13 to produce radial sliding on the surface of the object to be tested.

[0127] The radial slip here refers to a small displacement in the lateral direction relative to the probe axis, and its displacement path is determined by the spatial orientation of the contact slope 15. This slip will break the oxide layer, adsorption layer and dust layer on the surface of the test object, and gradually increase the number of micro-contact points, and the contact resistance will decrease from a high state to a stable state.

[0128] Since radial slip is determined by the slope geometry and spring compression, no additional servo actuator or force sensor is required; the lateral force component is determined by the geometry of the contact slope 15 and the compression state of the second spring 14, and is generated under the condition that the inner voltage probe 13 contacts the object under test and the second spring 14 is continuously compressed.

[0129] Furthermore, the logical relationship between steps S4 and S5 can be understood as follows: when the inner voltage probe 13 begins to contact the object under test, it enters the contact establishment stage; during this stage, the compression of the second spring 14 gradually increases from zero, and the micro-scratching caused by the contact inclined surface 15 occurs simultaneously.

[0130] As cylinder 4 continues to press down, the overall retraction of the probe assembly continues to accumulate. Only when the accumulated displacement reaches the threshold corresponding to the second photoelectric switch 9 is it considered that the contact establishment process has entered the predetermined contact depth range that can be used as the sampling starting point.

[0131] Therefore, the second photoelectric switch 9 does not correspond to a simple time delay, but rather to a mechanical threshold event characterized by the displacement of the cylinder 4, the compression of the first spring 11, the compression of the second spring 14, and the contact state of the probe.

[0132] In step S5, as the second spring 14 is further compressed, the outer ring current probe 10 continues to retract relative to the insulating sleeve 7, and the light shield 12 continues to move upward and block the second photoelectric switch 9; the characteristic time point when the second photoelectric switch 9 is blocked is obtained and recorded as the reference time point;

[0133] The reference time point here is the physical moment when the mechanical contact reaches the predetermined pressure state, which is used as the starting point for subsequent voltage sampling and calculation. Since this time point is determined by the actual displacement of the outer ring current probe 10 and has a corresponding relationship with the pressing depth of the inner ring voltage probe 13, the timing error caused by simple software delay can be eliminated, and the accuracy of timing triggering can be improved.

[0134] With the help of steps S1 to S5, the system can start the subsequent sampling process under uniform physical conditions even when there are deviations in the geometric dimensions of the object to be measured.

[0135] The predetermined pressure state here refers to the axial displacement state of the probe assembly corresponding to the second photoelectric switch 9. It is not directly measured by the pressure sensor, but is indirectly characterized by the pre-calibrated relationship between the installation height of the second photoelectric switch 9 and the spring parameters.

[0136] During calibration, a standard thickness block or a standard resistor can be selected to repeatedly press the device down to the trigger position of the second photoelectric switch 9, record the corresponding compression amount of the first spring 11, the compression amount of the second spring 14, or the total retraction amount of the probe, and determine the contact depth range represented by the second photoelectric switch 9 accordingly.

[0137] In the control process, the event that the second photoelectric switch 9 is blocked serves as the sole input for determining the start of subsequent sampling. Therefore, the source of the reference time point clearly corresponds to the moment when the probe reaches the contact depth range, rather than being derived from empirical estimation.

[0138] Furthermore, steps S1 to S5 sequentially form a sequence of approaching the object under test, confirming the minimum clamping of the outer current probe 10, establishing a constant current, forming the scraping contact of the inner voltage probe 13, and confirming the sampling reference time, wherein the output state of the previous event serves as the allowable condition for the next event.

[0139] Because the triggering link consists of two physical displacement thresholds and a constant current establishment action connected in series, the current establishment action precedes the voltage sampling action, and the voltage sampling action occurs within the known contact depth range, thus making the physical contact conditions corresponding to the subsequent sampling values ​​clearer.

[0140] In actual equipment configuration, to ensure that the radial sliding in step S4 is stable and controllable, the stiffness coefficient of the second spring 14 is preferably set to 0.5 N / mm to 2.0 N / mm;

[0141] When the cylinder 4 continues to descend, causing the probe assembly to reach the displacement threshold corresponding to the second photoelectric switch 9, the compression of the second spring 14 is usually between 0.2 mm and 0.8 mm, thereby establishing an axial clamping force of 0.1 N to 1.6 N on the contact interface.

[0142] The clamping force, in conjunction with the 5° contact slope 15, generates a lateral force component that can overcome the static friction between the probe and the surface of the object under test and induce micro-motion without causing mechanical indentation or damage to the substrate.

[0143] This configuration, based on a strict match between spring stiffness and displacement threshold, enables open-loop mechanical control to also possess highly repeatable contact quality.

[0144] Step S5 and the following steps include:

[0145] Step S601: Starting from the reference time point, continuously record the first voltage, the second voltage, and the third voltage at preset time intervals;

[0146] Step S602: Extract the first voltage, the second voltage, and the third voltage to calculate the stable voltage;

[0147] Step S603: Divide the stable voltage by the constant current to calculate the true resistance of the object under test;

[0148] After the reference time point is determined, this embodiment further calculates the actual resistance of the test object using early dynamic voltage data to reduce the time required for the contact to fully stabilize.

[0149] In step S601, starting from the reference time point, the first voltage, the second voltage, and the third voltage are continuously recorded at a preset time interval; the preset time interval is the time length between two adjacent voltage samples to maintain consistency, preferably set to 0.1ms to 5ms.

[0150] If the time interval is too short, the difference in sampling noise between adjacent sampling points may be close to the contact resistance attenuation; if the time interval is too long, it may reduce the early calculation's timing advantage; voltage sampling can be done by an analog-to-digital converter, with a resolution preferably not less than 16 bits to accommodate the detection of small voltage drops in low-resistance measurements.

[0151] The first voltage, the second voltage, and the third voltage correspond to the first, second, and third equally spaced sampled values ​​after the reference time point, respectively.

[0152] The first voltage, second voltage, and third voltage here refer to the instantaneous voltage drop sampled between the inner ring voltage probe 13 and the reference terminal under constant current. Physically, they include the actual voltage drop of the test object and the additional transient contact voltage drop when the contact is not yet fully stable.

[0153] The preset time interval can be determined by pre-calibration, that is, continuously collecting the voltage decay curve after contact for the target test object type, selecting a sampling interval that can distinguish the continuous decay trend without causing adjacent sampling points to be too close to the noise floor as the control parameter, and keeping it fixed during formal operation, so as to ensure that the three sampling values ​​are comparable.

[0154] In step S602, the first voltage, the second voltage, and the third voltage are extracted to calculate the stable voltage; here, the stable voltage refers to the estimated value of the actual voltage drop of the test object under constant current after the contact interface has completely stabilized.

[0155] This estimate does not rely on long waiting times, but rather utilizes the changing pattern of contact resistance decay over a short period of time, and is mathematically extrapolated through three consecutive sampling points;

[0156] This is because after the inner ring voltage probe 13 forms a repeatable micro-scratching under the action of the contact slope 15, the change in contact resistance from the initial state to the steady state can be approximated as a single decay process. Therefore, the steady limit value can be calculated using a finite number of sampling values.

[0157] The input sources for this calculation process are the three equally timed sample values ​​obtained in step S601 and the constant current state that the constant current source has established and maintained in step S3.

[0158] The processing sequence can be broken down into the following logical steps: The controller compares the magnitudes of the first voltage, the second voltage, and the third voltage to confirm that the sampling sequence conforms to the basic trend of gradual decrease in contact resistance; Under normal circumstances, the three sampled values ​​should decrease or tend to level off over time.

[0159] The controller uses the attenuation relationship between the first two intervals to evaluate the remaining deviation of the third voltage from the final stable value; the controller subtracts this deviation from the third voltage to obtain an estimate of the stable voltage; the final output of this process is the stable voltage, which is passed to step S603 as the input for the actual resistance calculation.

[0160] If the three sampled values ​​do not meet the expected attenuation trend, for example, if the later point is higher than the previous point and exceeds the allowable noise range, it can be determined that the contact process is disturbed. At this time, a resampling can be performed, or the waiting time can be extended before measurement to avoid sending abnormal data into subsequent calculations. Furthermore, the calculation used in step S602 is a short-sequence compensation model based on the assumption of gradual attenuation of contact pressure drop.

[0161] The purpose of this model is to estimate the remaining contact voltage drop that has not disappeared after the third sampling time by using the relative change relationship between the three early sampling points when it is impossible to wait for the contact interface to be completely still, and to remove it from the currently measured voltage.

[0162] The model logically includes a trend judgment unit, a residual deviation estimation unit, and a stable value output unit; the trend judgment unit receives the first voltage, the second voltage, and the third voltage, and determines whether they meet the basic conditions of decreasing or approximately decreasing.

[0163] When the trend is established, the residual deviation estimation unit uses the premise that the relative spacing of the three sampling points is the same to evaluate the tail deviation that still exists in the third voltage relative to the final stable voltage; the stable value output unit subtracts the estimated tail deviation from the third voltage and outputs the stable voltage.

[0164] The model as a whole represents the causal process of the contact interface transitioning from an initial high contact voltage drop to a stable low contact voltage drop under the action of compression and fretting. The time progression causes the transient contact voltage drop to gradually decrease, while the voltage drop of the test object remains basically unchanged under constant current. Therefore, the total sampling voltage shows a trend of approaching the stable limit value.

[0165] In step S603, the stable voltage is divided by the constant current to calculate the true resistance of the test object; the true resistance here refers to the resistance value of the test object in the corresponding stable conduction state after deducting the contact transient effect; since the constant current source has established a stable output in step S3, the stable voltage and constant current satisfy the ohmic relationship, so the resistance can be directly calculated.

[0166] By completing sampling and calculation early in the contact period before it is fully stable, the traditional waiting time can be shortened from tens of milliseconds to milliseconds, thereby accelerating the response speed of test signal acquisition. At the same time, the reference time point is determined by the mechanical threshold corresponding to the second photoelectric switch 9, ensuring that the three voltage sampling values ​​have uniform initial contact conditions, and keeping the calculation input consistent between different test cycles.

[0167] The actual resistance output here can be further compared with the qualified range set by the process to generate a judgment result of qualified, out of tolerance or retest. However, this judgment is a subsequent application of the output result of step S603 and does not affect the calculation logic of step S603 itself.

[0168] Furthermore, step S601 outputs three equally spaced original voltage sample values, step S602 outputs a stable voltage estimate after compensation for the remaining contact voltage drop, and step S603 converts the stable voltage into a real resistance value by matching it with the constant current setting value.

[0169] Since step S603 only performs ohm conversion on the already compensated stable voltage, its output result is directly related to the compensation effect of step S602; and precisely because step S602 first removes the contact transient component, the resistance value obtained in step S603 is closer to the resistance value of the object under test.

[0170] Step S602 specifically includes:

[0171] The numerator is obtained by subtracting the second voltage from the third voltage and calculating the square of the difference.

[0172] The denominator is obtained by summing the first voltage and the third voltage and then subtracting twice the second voltage.

[0173] When the absolute value of the denominator is greater than or equal to the preset effective threshold, the voltage compensation amount is calculated by dividing the numerator by the denominator.

[0174] The true voltage drop is obtained by subtracting the voltage compensation amount from the third voltage, and the true voltage drop is set as the stable voltage.

[0175] This embodiment elaborates on the specific calculation process of the stable voltage; let the first voltage be... The second voltage is The third voltage is The sampling time intervals among the three are the same and are all obtained by step S601;

[0176] During the calculation, first subtract the second voltage from the third voltage to obtain the difference value. Then, the square of the difference is calculated to obtain the numerator; the numerator reflects the quadratic relationship of the attenuation between the last two sampling points, and is related to the remaining amount that has not yet been attenuated under a single attenuation trend;

[0177] Continue summing the first voltage and the third voltage to obtain Subtract twice the second voltage, that is The denominator is obtained; this denominator essentially reflects the quadratic change at three equally timed sampling points, and is used to characterize the curvature of the decay curve.

[0178] If the contact voltage shows a decreasing trend within the sampling interval, then the denominator is a non-zero quantity that can be used for compensation calculation; divide the numerator by the denominator to obtain the voltage compensation amount; here, the voltage compensation amount is the estimated residual deviation of the third voltage relative to the stable voltage.

[0179] Then, subtract the voltage compensation amount from the third voltage to obtain the true voltage drop, and set the true voltage drop as the stable voltage; expressed in words, the stable voltage is equal to the third voltage minus the square of the difference between the second and third voltages divided by the sum of the first and third voltages minus twice the second voltage.

[0180] This calculation method relies on only three consecutive sampled values, eliminating the need to fit the entire curve or pre-store large amounts of historical data. It is suitable for real-time execution on production line controllers or embedded test boards. Specifically, the mathematical formulas corresponding to the above calculation process are as follows:

[0181]

[0182] in, This represents a stable voltage. The following is an explanation based on a specific quantitative deduction example: Assume that under the action of a constant current of 1A, the contact interface is in the resistance decay period of micro-scraping.

[0183] The controller acquires three consecutive voltage values ​​at a preset time interval of 1ms: the first voltage... The second voltage is 50.0mV. It is 40.0mV, the third voltage. The value is 34.0 mV; based on the above logic, the molecule is calculated as follows: The denominator is calculated as follows: Voltage compensation amount is The final calculated stable voltage is: ;

[0184] In this simulation, the remaining 9.0mV transient deviation that had not yet completely decayed was removed through calculation, and a stable voltage of 25.0mV was obtained.

[0185] To improve the reliability of this method in practical applications, a denominator threshold judgment can be set in the actual control program. When the absolute value of the calculated denominator is less than the preset threshold, it can be determined that the change in the sampled value is lower than the preset change threshold or the noise amplitude is higher than the preset noise threshold. At this time, a resampling can be added or a third voltage can be used as an approximate stable voltage.

[0186] The preset threshold can be set according to the resolution and range of the analog-to-digital converter, for example, it can be set to 0.001% to 0.01% of the full range. Through the above processing, the feasibility of the calculation is guaranteed, and the instability of the value due to the denominator being too small is avoided.

[0187] When this calculation process is used in conjunction with the aforementioned mechanical structure, it can obtain a near-steady-state voltage drop before the contact has completely stopped, which can be used for rapid measurement of low resistance.

[0188] The above calculation process can be further broken down according to the controller execution sequence as follows: First, read the output of step S601. , , First, check if the three samples come from the same sampling interval condition; if the sampling clock is abnormal, the current sampling data is determined to be invalid; second, calculate the attenuation between the last two sampling points, and construct a calculation numerator with the attenuation amount to characterize the degree to which the attenuation has not yet ended at the current time.

[0189] The third step is to construct a calculation denominator using the quadratic change formed by the three sampling points to determine whether the attenuation curve has sufficient curvature to support the calculation; the fourth step is to execute the compensation calculation when the absolute value of the calculation denominator is greater than or equal to the preset threshold and the three sampling points meet the predetermined trend conditions; the fifth step is to subtract the compensation from the third voltage, output a stable voltage, and pass the stable voltage to step S603.

[0190] The preferred trend conditions here are: ,and When the difference between two adjacent values ​​is less than the noise allowable range, they can also be considered equal. The noise allowable range can be set according to the quantization step of the analog-to-digital converter, the zero drift of the front-end amplifier, and the historical no-load noise test results. For example, the voltage range corresponding to 3 to 10 quantization code values ​​can be taken.

[0191] The purpose of using this trend judgment is to first confirm that the three sampling points do indeed reflect the contact voltage drop attenuation process before proceeding with the compensation calculation, thereby avoiding incorrect extrapolation of non-attenuation anomaly data;

[0192] When determining the preset threshold and noise allowable range, it can be obtained through prototype calibration. Specifically, several standard parts with known resistance values ​​can be selected, and the test cycle can be repeatedly executed under the same constant current. The range of changes in the three sampling points at the initial contact stage, the no-load noise, the voltage fluctuation after stable contact, and the change range can be statistically analyzed. Based on this, parameters that can identify the true attenuation and suppress the amplification of random noise can be set. Thus, the sampled values ​​are first judged for validity, and then the compensation value is obtained to output a stable voltage.

[0193] Furthermore, the above compensation calculation can be understood as a multi-point data extrapolation method for the monotonic decay tail. Its purpose is not to reconstruct the complete decay curve, but to estimate the remaining part that has not yet decayed after the third sampling point by using the correspondence between the decay amount and the curvature of the curve before and after the three sampling points with equal time intervals.

[0194] Because the voltage drop of the test object is basically constant under constant current conditions, while the contact transient voltage drop decays over time, the difference between the three sampling points mainly comes from this transient component. Furthermore, since the numerator represents the current decay intensity between the last two points and the denominator represents the decay bending characteristics formed by the three points, the compensation obtained by dividing the two can be used as an estimate of the residual deviation that the third voltage is still higher than the stable voltage. Based on this, the controller subtracts the residual deviation from the third voltage and outputs the stable voltage.

[0195] In step S3, based on the condition of injecting a constant current into the outer current probe 10, the inner voltage probe 13 is forced to be in an open circuit state without contacting the object under test.

[0196] This embodiment emphasizes that when the constant current source output is established in step S3, the inner voltage probe 13 remains in an open circuit state without contacting the object under test; the open circuit state here means that the inner voltage probe 13 and the object under test have not yet formed a conductive contact, and the voltage sampling input terminal does not bear the contact current impact at the moment of injection.

[0197] This state is naturally achieved by the mechanical structure. That is, the outer current probe 10 first contacts the object under test and compresses the first spring 11. After the first photoelectric switch 8 is blocked, it immediately triggers the constant current source output. At this time, the inner voltage probe 13 still maintains a physical isolation gap or is only in a non-conductive approach state due to the existence of the second spring 14 and the coaxial height difference. Through this sequential contact relationship, the contact between the current-passing contact and the voltage-measuring contact can be separated instantly.

[0198] In low resistance testing, if the voltage probe simultaneously undertakes a current build-up process exceeding its threshold at the moment of contact, the probe tip may experience transient discharge or micro-ablation due to the local contact area not meeting the stable conduction requirements. After long-term operation, this will change the probe tip morphology and contact resistance.

[0199] By forcing the inner voltage probe 13 to remain in an open circuit state, the constant current source output can first form a stable current path through the outer current probe 10 and the device under test. After the current is established, the inner voltage probe 13 then contacts the device under test with a preset measurement load, and only undertakes the voltage sampling function. This can reduce the wear caused by current-carrying contact at the end of the voltage probe and improve the long-term measurement consistency.

[0200] In terms of control implementation, no additional electronic actuator is needed to actively lift the inner ring voltage probe 13; being forced into an open circuit state means that by utilizing the outer ring current probe 10, the inner ring voltage probe 13, the first spring 11, the second spring 14, and their axial relative positional relationship, the inner ring voltage probe 13 must not have been in contact with the object under test at the moment the first photoelectric switch 8 is triggered.

[0201] To ensure this relationship, the initial height difference between the bottom of the outer ring current probe 10 and the bottom of the inner ring voltage probe 13 can be set during the design, for example, 0.1mm to 1.0mm. Combined with the installation position of the first photoelectric switch 8 and the compression amount of the first spring 11, the retraction displacement of the outer ring current probe 10 when the constant current source is triggered is less than the displacement required for the inner ring voltage probe 13 to reach contact.

[0202] With the help of this mechanical timing constraint, the timing requirement of applying current before measuring voltage can be repeatedly achieved in each test cycle.

[0203] Step S603 and the following steps include:

[0204] Step S701: Control cylinder 4 to drive lifting plate 6 to retract to the initial zero position;

[0205] Step S702: Cut off the constant current source output to complete the test cycle;

[0206] After the actual resistance calculation is completed, this implementation method ends a single test cycle by retraction and power-off actions, in preparation for the next test.

[0207] In step S701, the control cylinder 4 drives the lifting plate 6 to retract to the initial zero position; the initial zero position here means that the lifting plate 6, the insulating sleeve 7, the outer current probe 10 and the inner voltage probe 13 return to the standby position before contacting the object under test.

[0208] During the retraction process, the supporting effect of the test object on the outer current probe 10 and the inner voltage probe 13 is released, the first spring 11 and the second spring 14 release elastic potential energy, so that the outer current probe 10 is reset downward relative to the insulating sleeve 7, and the inner voltage probe 13 is also restored to the free extension state relative to the outer current probe 10.

[0209] As the light-shielding plate 12 moves downward along with the outer ring current probe 10, it sequentially exits the detection areas of the second photoelectric switch 9 and the first photoelectric switch 8, and the two photoelectric switches return to the unshielded state, providing initial judgment conditions for the next test cycle.

[0210] The retraction speed of cylinder 4 can be set to be the same as or slightly higher than the downward speed, such as 100mm / s to 250mm / s, to balance the timing and mechanical impact. To avoid vibration when retracting to the end, the speed can be reduced at the end near the zero position, or the impact can be reduced by the cushioning structure of cylinder 4.

[0211] After returning to the zero position, the control system can read the origin sensor, cylinder 4 magnetic switch or stroke count signal to confirm that the return is complete; if it does not return to the set position, it can trigger fault protection to prevent the next test from being performed in a non-initial state.

[0212] In step S702, the constant current source output is cut off to complete the test cycle. Disconnecting the constant current source can prevent the probe from being continuously powered in a non-measurement contact state, reduce unnecessary heat generation and energy consumption, and also avoid tailing current during the process of the probe leaving the test object.

[0213] The cut-off time can be set to be executed immediately after the actual resistance calculation is completed, or it can be set to be executed when the lifting plate 6 begins to retract, as long as the voltage measurement is completed before the subsequent probe leaves the object under test.

[0214] By combining steps S701 and S702, each test cycle ends with uniform mechanical and electrical initial conditions, ensuring that the triggering time of the first photoelectric switch 8, the reference time point of the second photoelectric switch 9, and the acquisition conditions of the three voltage sampling values ​​remain consistent in the next cycle, thereby improving the repeatability of continuous batch testing.

[0215] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A resistance detection device, characterized in that, include: Test base (1); A support column (2) is fixedly connected to the test base (1) at its bottom end and a top plate (3) is fixedly connected to its top end. The cylinder (4) is fixedly connected to the top plate (3). The piston rod (5) of the cylinder (4) extends vertically downward and is connected to the lifting plate (6) at the end. An insulating sleeve (7) is fixedly connected to the lower surface of the lifting plate (6). The outer side wall of the insulating sleeve (7) is provided with a first photoelectric switch (8) and a second photoelectric switch (9) in sequence along the vertical direction. The second photoelectric switch (9) is located below the first photoelectric switch (8). The outer ring current probe (10) has an outer cylindrical surface that is clearance-fitted with the inner hole of the insulating sleeve (7). A first spring (11) is pressed between the top of the outer ring current probe (10) and the inner top surface of the insulating sleeve (7). A vertical guide groove (16) is provided on the side wall of the insulating sleeve (7) in the vertical direction. A light shield (12) that passes through the vertical guide groove (16) is provided on the upper part of the outer side wall of the outer ring current probe (10). The inner ring voltage probe (13) has an outer cylindrical surface that is clearance-fitted with the inner hole of the outer ring current probe (10). A second spring (14) is pressed between the top of the inner ring voltage probe (13) and the inner top surface of the outer ring current probe (10). The bottom end face of the inner ring voltage probe (13) is provided with a contact slope (15).

2. The resistance detection device according to claim 1, characterized in that, The light-shielding plate (12) is fixedly connected to the upper part of the outer wall of the outer ring current probe (10) by interference fit.

3. The resistance detection device according to claim 1, characterized in that, The inclination angle of the contact slope (15) at the bottom end face of the inner ring voltage probe (13) is 5°.

4. The resistance detection device according to claim 1, characterized in that, The outer ring current probe (10) is a cylindrical structure made of beryllium copper, the inner ring voltage probe (13) is a cylindrical structure made of tungsten steel, and the insulating sleeve (7) is a hollow cylinder made of polytetrafluoroethylene.

5. The resistance detection device according to any one of claims 1 to 4, characterized in that, The bottom end of the support column (2) is fixedly connected to the test base (1) by bolts, and the top end of the support column (2) is fixedly connected to the top plate (3) by welding. The center hole of the lifting plate (6) is connected to the end of the piston rod (5) of the cylinder (4) by thread.

6. A testing method applied to the resistance detection device according to claim 1, characterized in that, include: S1. Control the cylinder (4) to drive the lifting plate (6) to move downward, thereby causing the insulating sleeve (7), the outer ring current probe (10) and the inner ring voltage probe (13) to descend as a whole; S2, the bottom end of the outer ring current probe (10) contacts the surface of the object to be tested, the cylinder (4) continues to descend to compress the first spring (11), the outer ring current probe (10) slides upward relative to the insulating sleeve (7) and drives the light shield (12) to move upward to block the first photoelectric switch (8). S3. Obtain the trigger signal of the first photoelectric switch (8) being blocked, control the constant current source to output and inject a constant current into the outer ring current probe (10); S4. The cylinder (4) continues to descend, and the contact slope (15) of the inner ring voltage probe (13) contacts the surface of the object to be tested and generates a lateral force component under the downward pressure of the second spring (14), causing the bottom end of the inner ring voltage probe (13) to slide radially on the surface of the object to be tested. S5. As the second spring (14) is further compressed, the light-shielding plate (12) continues to move upward and block the second photoelectric switch (9), and the reference time point when the second photoelectric switch (9) is blocked is obtained.

7. The test method according to claim 6, characterized in that, Step S5 is followed by: S601. Starting from the reference time point, continuously record the first voltage, the second voltage, and the third voltage at equal time intervals; S602. A stable voltage is calculated based on the first voltage, the second voltage, and the third voltage. S603. The true resistance of the object under test is calculated by dividing the stable voltage by the constant current.

8. The test method according to claim 7, characterized in that, The steps of S602 specifically include: taking the difference between the second voltage and the third voltage, and squaring the difference to obtain the numerator; and subtracting twice the second voltage from the sum of the first voltage and the third voltage to obtain the denominator. When the absolute value of the denominator is determined to be greater than or equal to a preset effective threshold, the numerator is divided by the denominator to calculate the voltage compensation amount; the third voltage is subtracted from the voltage compensation amount to obtain the true voltage drop, and the true voltage drop is used as the stable voltage.

9. The test method according to claim 6, characterized in that, In step S3, when a constant current is injected into the outer current probe (10), the inner voltage probe (13) is in an open-circuit state before it comes into contact with the object under test.

10. The test method according to claim 7, characterized in that, The steps following S603 include: S701, controlling the cylinder (4) to drive the lifting plate (6) back to the initial position; S702, cutting off the constant current source output to complete the test cycle.

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