Method and Device for Welding Quality Detection

Abstract

The present application provides a method and apparatus for detecting welding quality. The method comprises the steps of: obtaining a maximum resistance value of a molten core at the end of welding current application (where the resistance value is maximum at the end of current application and the start of cooling); obtaining an initial resistance value and a final resistance value of the molten core during the cooling phase; calculating the difference between the initial resistance value and the final resistance value; determining the diameter of the molten core based on the maximum resistance value and the difference value; and determining welding quality based on the diameter of the molten core. The present application accurately and non-destructively evaluates welding quality by obtaining the maximum resistance value of the molten core at the end of welding current application and the initial and final resistance values ​​of the cooling phase, calculating the difference value, and then determining the diameter of the molten core by combining the maximum resistance value of the molten core at the end of current application.

Description

Technology Field

[0001] This application belongs to the field of molten core detection, and in particular relates to a method and apparatus for detecting welding quality. Background Technology

[0002] Resistance welding is a widely used metal sheet joining technique, and the quality of the weld is directly related to the overall performance and safety of the product. The size of the molten core is one of the important indicators for evaluating weld quality, as it is closely related to the strength and integrity of the molten core. Currently, the methods commonly used in the industry for detecting molten core size are primarily metallographic analysis and stripping tests. However, since these methods are all destructive detection methods, the parts cannot be reused after detection, the detection process is time-consuming, and they are mainly used for sampling inspections, failing to meet the demand for online detection. Although ultrasonic technology can implement non-destructive detection, its widespread application is limited due to issues such as high device costs and slow detection speeds.

[0003] The purpose of the present application is to overcome the defects of the prior art and to provide a method and apparatus for detecting welding quality.

[0004] The present application relates to a welding quality detection method,

[0005] A step of obtaining the maximum resistance value of the molten core when the welding current of the metal material is terminated;

[0006] A step of obtaining the initial resistance value and the final resistance value of the molten core during the cooling phase;

[0007] A step of calculating the difference between the initial resistance value and the final resistance value;

[0008] A step of determining the molten core diameter based on the maximum resistance value and the difference value;

[0009] A welding quality detection method is provided, characterized by including a step of determining welding quality based on the molten core diameter.

[0010] Optionally, the step of obtaining the maximum resistance value of the molten core at the end of the welding current application of the metal material includes the step of measuring the maximum resistance value at the moment of current interruption, which is the final time of the welding current application step;

[0011] The step of obtaining the initial resistance value and the final resistance value of the molten core during the cooling phase includes obtaining the initial resistance value through the T0-T1 time period and obtaining the final resistance value through the T2-T3 time period.

[0012] Optionally, the step of calculating the difference between the initial resistance value and the final resistance value is,

[0013] It includes a step of calculating the arithmetic difference between the initial resistance value and the final resistance value, and having a preset cooling time interval between the T0-T1 and T2-T3 time zones.

[0014] Optionally, the step of determining the molten core diameter based on the maximum resistance value and the difference value is,

[0015] The correspondence between the difference value and the molten core diameter is corrected through multi-element welding experiments, and the multi-element includes a step in which process parameters such as welding current, welding pressure, current application time, electrode size, and cooling water temperature and the process are included.

[0016] Optionally, the step of determining welding quality based on the molten core diameter is,

[0017] Establishing a standard range for the resistance difference value of an acceptable weld point, and the standard includes the step of including process parameters, electrode diameter, and cooling water temperature variables.

[0018] Optionally, when acquiring the initial resistance value and the final resistance value,

[0019] The applied test current intensity is 1 / 10 to 1 / 1000 of the welding current, and the single energization time is controlled to a microsecond (μs) to millisecond (ms) level.

[0020] The present application also relates to a welding quality detection device,

[0021] Welding clamp voltage and current signal collection device connected to upper and lower welding electrodes;

[0022] A signal processing module connected to a collection device that performs filtering and amplification on voltage and current signals;

[0023] An A / D conversion module connected to a signal processing module that converts analog signals into digital signals;

[0024] It includes a network communication module connected to an A / D conversion module to transmit digitized signals and implement inter-device interconnection.

[0025] Optionally, the voltage and current channels of the A / D conversion module are each connected to the two working surfaces of the welding electrode.

[0026] Optionally, the data transmitted by the network communication module includes a sequence of resistance measurements R_max, R_initial, and R_final.

[0027] Optionally, the welding clamp voltage signal and current signal acquisition device synchronously acquires the welding circuit signal at a 1 MHz sampling rate, and the A / D conversion module completes the maximum resistance value freezing calculation within 5 ms after the welding current is cut off.

[0028] The beneficial effects of the present application are as follows. The present application provides a method for detecting welding quality, which accurately and non-destructively evaluates welding quality by obtaining the maximum resistance value during welding and the initial and final resistance values ​​of the cooling phase, calculating the difference between them, and then combining the maximum resistance values ​​to determine the molten core diameter. Brief explanation of the drawing

[0029] FIG. 1 is a schematic diagram of a flowchart of a welding quality detection method according to the present application; FIG. 2 is a schematic diagram of an embodiment of a welding quality detection device according to the present application. Specific details for implementing the invention

[0030] Exemplary embodiments of the present disclosure are described in more detail below with reference to the drawings. Although exemplary embodiments of the present disclosure are illustrated in the drawings, it will be understood that the present disclosure is not limited to the embodiments described herein and can be implemented in various forms. The embodiments are intended to provide a clearer understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0031] In the metal welding process, the dynamic characteristics of the molten core formation and cooling phases determine the welding quality. The detection method of the present application captures the molten core resistance value in real time at the end of welding current application and combines it with an analysis of resistance changes during the cooling phase to enable accurate calculation of the molten core size and quality determination.

[0032] Referring to FIG. 1, a welding quality detection method according to an embodiment of the present application comprises the following steps:

[0033] S101, a step of obtaining the maximum resistance value of the molten core when the welding of the metal material ends;

[0034] When the welding current is fully applied and cut off according to a preset time, the molten core reaches its maximum size and begins cooling. At this time, the Hall voltage sensor and Rogowski coil current sensor integrated into the welding clamp electrode synchronously collect signals including voltage and current signals.

[0035] For example, the voltage signal has a measurement range of 0-5.0V and an accuracy of ±0.1%, and removes power interference through a 50Hz power frequency and a 1000Hz intermediate frequency notch filter. The current signal has a measurement range of 0-20kA and a bandwidth of 1MHz, and suppresses high-frequency noise through a 10kHz low-pass filter.

[0036] Calculate resistance values ​​in real time according to Ohm's Law:

[0037]

[0038] Data is frozen within 5ms after current cutoff to prevent interference with the initial resistance drop during cooling.

[0039] S102, a step of obtaining the initial resistance value and the final resistance value of the molten core during the cooling phase;

[0040] Initial resistance value (R initial ) measurement:

[0041] The time period from 0 to 10 ms after the start of cooling is set as the T0-T1 time period and used as the time period for measuring the initial current resistance value. A microcurrent at a level of 1 / 10 to 1 / 1000 of the welding current (e.g., a 10 A test current corresponding to a 10 k A welding current) is applied, and the pulse width is 10 to 50 μs.

[0042] Measure current and voltage synchronously and calculate as follows:

[0043]

[0044] Termination resistance value (R final ) measurement:

[0045] Set 110-120ms after the start of cooling as the T2-T3 time zone, use it as the time zone for measuring the end resistance value, and set it at an interval of 100ms from T0-T1;

[0046] Obtain the current and voltage at the same level of microcurrent and calculate as follows:

[0047]

[0048] R initial and R final is the average value of the measurements.

[0049] The T0-T1 time interval captures the rapid drop in resistance during the initial cooling of the molten core, and the T2-T3 time interval reflects the termination state after stable shrinkage. By setting the interval time, ΔR is made to better represent the material phase transition process.

[0050] S103, a step of calculating the difference between the initial resistance value and the final resistance value;

[0051] Resistance change ΔR=R initial － R final Calculate.

[0052] Microcurrent testing prevents secondary heating of the molten core, thereby ensuring the integrity of the component. At the same time, ΔR can effectively distinguish between cold solder joints and sputtering.

[0053] S104, a step of determining the molten core diameter based on the maximum resistance value and the difference value;

[0054] Qualitative model (D1): Pre-saved formula D1 = 0.05R max R based on + 2.0 max Map to the melt core diameter.

[0055] Quantitative model (D2): The cooling shrinkage effect is corrected using D2 = 0.1ΔR + 1.5.

[0056] First, calculate the melt core size using a qualitative model. R max If it does not exceed the preset range, the melt core size is calculated using a quantitative model.

[0057] R max If relying solely on it, the error is high due to the unpredictability of welding quality;

[0058] If relying solely on ΔR, it is not possible to distinguish differences in the initial size of the molten core (e.g., the ΔR of the cold solder joint and the passing weld point may overlap).

[0059] Rmax directly reflects the maximum size at the moment of molten core formation, and ΔR reflects the shrinkage effect during the cooling process. Combining the two values ​​can offset the deviation of a single parameter measurement.

[0060] S105 includes a step of determining welding quality based on the molten core diameter.

[0061] R maxIf it exceeds the preset range, it is determined to be a direct quality abnormality.

[0062] R max R of the normal weld point max Cold solder joints and sputtering are qualitatively determined by deviations from the range, and R max A normal R max If it is larger than the range, it is determined to be cold solder joint, and if it is smaller, it is determined to be sputtering.

[0063] The acceptable weld point is molten core ≥ (t is the plate thickness, in mm) must be satisfied; and ΔR must be within ±15% of a preset value.

[0064] The judgment result (pass / cold solder / sputtering / cooling abnormality) is transmitted to the welding controller in real time via the Modbus-TCP protocol;

[0065] Data packets are timestamps, R max It is synchronously uploaded to the MES system including parameters such as , ΔR, and D.

[0066] Referring to FIG. 2, the welding quality detection device according to the present application includes a welding clamp voltage signal acquisition device (201), a current signal acquisition device (202), a signal processing module (203), an A / D conversion module (204), a processor (not shown), and a network communication module (205);

[0067] The voltage signal acquisition device (201) and current signal acquisition device (202) of the welding clamp are connected to the welding clamp electrode. Specifically, a Hall voltage sensor and a Rogowski coil current sensor are integrated into the working surface of the welding gun electrode to synchronously capture the voltage / current signals of the welding circuit at a sampling rate of 1 MHz.

[0068] The signal processing module (203) is connected to the voltage signal acquisition device (201) and the current signal acquisition device (202) to perform filtering and amplification on the voltage signal and the current signal, which removes interference using a 50 Hz power frequency and a 1000 Hz intermediate frequency notch filter, and includes adding a 10 kHz low-pass filter to the voltage channel. The signal processing module (203) includes a program-controlled amplifier unit that applies a 100x fixed gain to the voltage signal and a 50x self-adaptive gain to the current signal.

[0069] The A / D conversion module (204) is connected to the signal processing module to convert the analog signal into a digital signal, which includes two 16-bit A / D converters each performing synchronous digital processing at a sampling rate of 250 kSPS. The voltage channel is connected to the electrode positive through the signal processing module, and the current channel removes common mode noise through the differential input.

[0070] The A / D conversion module (204) inputs current and voltage signals into a processor (not shown in FIG. 2) and performs the following processing:

[0071] R max Real-time calculation: Complete resistance value freezing capture within 5ms after welding current interruption;

[0072] ΔR Dynamic Detection: Automatically extracts resistance characteristic values ​​according to preset T0-T1 and T2-T3 time intervals. And R max Welding quality is determined based on , ΔR and D.

[0073] Network communication module (205): {R containing a timestamp via the Modbus-TCP protocol max A data sequence of , ΔR, D} is transmitted to a welding controller, and a welding quality detection device shares the quality judgment result with the welding controller to implement closed-loop control.

[0074] The above embodiments are intended to enable those skilled in the art to understand and apply the present invention. Those skilled in the art may make various modifications to the above embodiments and may apply the general principles described herein to other embodiments without creative effort. The present invention is not limited to the above embodiments. All improvements and modifications made by those skilled in the art in accordance with this disclosure must be within the scope of protection of the present invention.

Claims

Claim 1 A welding quality detection method comprising: a step of obtaining a maximum resistance value of a molten core when welding metal materials is terminated; a step of obtaining an initial resistance value and a final resistance value of the molten core during a cooling step; a step of calculating a difference value between the initial resistance value and the final resistance value; a step of determining a molten core diameter based on the maximum resistance value and the difference value; and a step of determining welding quality according to the molten core diameter. Claim 2 A welding quality detection method according to claim 1, wherein the step of obtaining the maximum resistance value of the molten core at the end of welding current application of the metal material includes the step of measuring the maximum resistance value at the moment of current interruption, which is the final time of the welding current application step; and the step of obtaining the initial resistance value and the end resistance value of the molten core in the cooling step includes the step of obtaining the initial resistance value through the T0-T1 time period and obtaining the end resistance value through the T2-T3 time period. Claim 3 A welding quality detection method according to claim 2, wherein the step of calculating the difference between the initial resistance value and the final resistance value includes the step of calculating the arithmetic difference between the initial resistance value and the final resistance value, and the step of having a preset cooling time interval between the T0-T1 and T2-T3 time periods. Claim 4 A welding quality detection method according to claim 1, wherein the step of determining the molten core diameter based on the maximum resistance value and the difference value comprises the step of correcting the correspondence relationship between the difference value and the molten core diameter through a multi-element welding experiment, and wherein the multi-element includes process parameters such as welding current, welding pressure, current application time, electrode size, and cooling water temperature and process. Claim 5 A welding quality detection method according to claim 1, wherein the step of determining welding quality according to the molten core diameter includes establishing a standard for a resistance difference value range of an acceptable welding point, and the standard includes process parameters, electrode diameter, and cooling water temperature variables. Claim 6 A welding quality detection method according to claim 1, characterized in that when obtaining an initial resistance value and a final resistance value, the applied test current intensity is at a level of 1 / 10 to 1 / 1000 of the welding current, and the single current application time is controlled to a level of microseconds (μs) to milliseconds (ms). Claim 7 A welding quality detection device comprising: a welding clamp voltage signal and current signal acquisition device connected to upper and lower welding electrodes; a signal processing module connected to the acquisition device and performing filtering and amplification on the voltage signal and current signal; an A / D conversion module connected to the signal processing module and converting an analog signal into a digital signal; and a network communication module connected to the A / D conversion module and transmitting the digitized signal and implementing inter-device interconnection. Claim 8 A welding quality detection device according to claim 7, characterized in that the voltage channel and the current channel of the A / D conversion module are each connected to two working surfaces of the welding electrode. Claim 9 A welding quality detection device according to claim 7, characterized in that the data transmitted by the network communication module includes a sequence of resistance measurement values ​​of R_max, R_initial, and R_final. Claim 10 A welding quality detection device according to claim 7, wherein the welding clamp voltage signal and current signal acquisition device synchronously acquires welding circuit signals at a 1 MHz sampling rate, and the A / D conversion module completes the maximum resistance value freezing calculation within 5 ms after the welding current is cut off.

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