Welding quality detection method and device

Abstract

The invention provides a welding quality detection method and device. The method comprises the steps that the maximum resistance value of a nugget at the end of metal material welding electrification (the maximum resistance value at the beginning of cooling at the end of electrification) is obtained; the initial resistance value and the final resistance value of the nugget are obtained in the cooling stage; calculating a difference value between the initial resistance value and the final resistance value; determining the nugget diameter based on the maximum resistance value and the difference value; and the welding quality is judged according to the nugget diameter. According to the method, the maximum resistance value of the nugget at the end of welding electrification and the initial resistance value and the final resistance value of the cooling stage are obtained, the difference value is calculated, and the diameter of the nugget is determined by combining the maximum resistance value of the nugget at the end of electrification, so that the welding quality is accurately and nondestructively evaluated.

Description

Technical Field

[0001] This application belongs to the field of nugget detection, and particularly relates to a welding quality detection method and device. Background Art

[0002] Resistance welding, as a widely used metal sheet connection technology, the quality of its welding directly affects the overall performance and safety of the product. The size of the nugget is one of the important indicators for measuring welding quality, as it is closely related to the strength and integrity of the nugget. Currently, the commonly used methods for detecting nugget size in the industry mainly include metallographic analysis and peel test. However, these methods are all destructive tests, that is, the workpiece after detection cannot be used again, and the detection process takes a long time, and is mostly used for sampling inspection, which cannot meet the requirements of on-line detection. Although ultrasonic technology can achieve non-destructive detection, there are problems such as expensive equipment and slow detection speed, which limit its wide application. Summary of the Invention

[0003] The purpose of this application is to overcome the defects in the above-mentioned prior art and provide a welding quality detection method and device.

[0004] This application provides a welding quality detection method, including:

[0005] Obtaining the maximum resistance value of the nugget at the end of the welding power-on of the metal material;

[0006] Obtaining the initial resistance value and the final resistance value of the nugget during the cooling stage;

[0007] Calculating the difference between the initial resistance value and the final resistance value;

[0008] Determining the nugget diameter based on the maximum resistance value and the difference;

[0009] Judging the welding quality according to the nugget diameter.

[0010] Optionally, obtaining the maximum resistance value of the nugget at the end of the welding power-on of the metal material includes: measuring the maximum resistance value at the moment of current cut-off at the final moment of the welding power-on stage;

[0011] Obtaining the initial resistance value and the final resistance value of the nugget during the cooling stage includes: obtaining the initial resistance value through the TO-T1 time window and obtaining the final resistance value through the T2-T3 time window.

[0012] Optionally, calculating the difference between the initial resistance value and the final resistance value includes:

[0013] The arithmetic difference between the initial resistance value and the final resistance value, and there is a preset cooling time interval between the TO-T1 and T2-T3 windows.

[0014] Optionally, determining the nugget diameter based on the maximum resistance value and the difference value includes:

[0015] The corresponding relationship between the difference value and the nugget diameter is calibrated through multi-factor welding experiments. The multi-factors include: process parameters: welding current, welding pressure, energization time, electrode size, and cooling water temperature and flow rate.

[0016] Optionally, determining the welding quality according to the nugget diameter includes:

[0017] Establishing a standard for the resistance difference range of qualified solder joints, and the standard covers process parameters, electrode diameter, and cooling water temperature variables.

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

[0019] The applied test current intensity is in the order of 1 / 10 to 1 / 1000 of the welding current, and the single energization time is controlled in the microsecond to millisecond level.

[0020] This application also provides a welding quality detection device, including:

[0021] A welding tong voltage signal and current signal acquisition device, connected to the upper and lower welding electrodes;

[0022] A dual-channel signal processing module, connected to the acquisition device, for filtering and amplifying the voltage signal and the current signal;

[0023] A dual-channel A / D conversion module, connected to the signal processing module, for converting analog signals into digital signals;

[0024] A network communication module, connected to the A / D conversion module, for transmitting digital signals and realizing device interconnection.

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

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

[0027] Optionally, the welding tong voltage signal and current signal acquisition device synchronously acquires welding loop signals at a sampling rate of 1 MHz, and the dual-channel 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 this application are:

[0029] This application provides a welding quality detection method, including: obtaining the maximum resistance value of the fusion nucleus during the welding of metal materials; obtaining the initial resistance value and the final resistance value of the fusion nucleus during the cooling stage; calculating the difference between the initial resistance value and the final resistance value; determining the diameter of the fusion nucleus based on the maximum resistance value and the difference; and determining the welding quality according to the diameter of the fusion nucleus. This application accurately and nondestructively evaluates the welding quality by obtaining the maximum resistance value during welding and the initial and final resistance values during the cooling stage, calculating their difference, and then combining the maximum resistance value to determine the diameter of the fusion nucleus. Description of the Drawings

[0030] Figure 1 is a schematic diagram of the welding quality detection process in this application;

[0031] Figure 2 is a schematic diagram of the fusion nucleus detection device in this application. Detailed Embodiments

[0032] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it can be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, the embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0033] During the welding process of metal materials, the formation and dynamic characteristics of the fusion nucleus during the cooling stage directly determine the welding quality. The detection method proposed in this application realizes the accurate calculation of the fusion nucleus size and quality determination by capturing the resistance value of the fusion nucleus at the end of welding power-on in real time and analyzing the resistance change during the cooling stage.

[0034] Please refer to Figure 1 as shown, this application provides a welding quality detection method, including:

[0035] S101. Obtain the maximum resistance value of the fusion nucleus at the end of the welding power-on of the metal material;

[0036] When the welding current completes power-on and is cut off according to the preset time, the fusion nucleus reaches the maximum size and begins to cool. At this time, the Hall voltage sensor and the Rogowski coil current sensor integrated on the welding electrode synchronously collect signals, including: voltage signals and current signals.

[0037] For example: Voltage signal: range 0 - 5.0V, accuracy ±0.1%, passing through a 50Hz power frequency and 1000HZ intermediate frequency notch filter to eliminate power supply interference; Current signal: range 0 - 20kA, bandwidth 1MHz, suppressing high-frequency noise through a 10kHz low-pass filter.

[0038] Calculate the resistance value in real time according to Ohm's law:

[0039]

[0040] And freeze the data within 5 ms after the current is cut off to avoid interference from the resistance drop at the initial stage of cooling.

[0041] Step S102: Obtain the initial resistance value and the final resistance value of the fusion core during the cooling stage;

[0042] Initial resistance value (R initial ) measurement:

[0043] Set the time period from 0 - 10 ms after the start of cooling as the T0 - T1 window, which serves as the measurement window for the initial current resistance value; Apply a micro - current in the order of 1 / 10 to 1 / 1000 of the welding current (for example, a 10 kA welding current corresponds to a 10 A test current), and set the pulse width to 10 - 50 μs.

[0044] Simultaneously measure the current and voltage, and calculate:

[0045]

[0046] Final resistance value (R final ) measurement:

[0047] Set the time period from 110 - 120 ms after the start of cooling as the T2 - T3 window, which serves as the measurement window for the final resistance value, with a 100 ms interval from T0 - T1;

[0048] Obtain the current and voltage under the same - order micro - current and calculate:

[0049]

[0050] The said R initial and the said R final can both be the measurement means.

[0051] The T0 - T1 window captures the rapid resistance drop during the initial cooling of the fusion core, and the T2 - T3 window reflects the final state after stable contraction. The designed interval time enables ΔR to better characterize the material phase - change process.

[0052] Step S103: Calculate the difference between the initial resistance value and the final resistance value;

[0053] Calculate the resistance change value ΔR = R initial - R final .

[0054] The micro - current test avoids secondary heating of the fusion core and ensures the integrity of the workpiece. At the same time, ΔR can effectively distinguish between false soldering and spatter.

[0055] Step S104: Determine the diameter of the fusion core based on the maximum resistance value and the difference value;

[0056] Qualitative model (D1): Based on the pre - stored formula D1 = 0.05R max + 2.0, map R max to the nugget diameter.

[0057] Quantitative model (D2): Use D2 = 0.1ΔR + 1.5 to correct the cooling shrinkage effect.

[0058] First, use the qualitative model to calculate the nugget size. If R max does not exceed the preset range, then use the quantitative model to calculate the nugget size.

[0059] If only relying on R max , due to the unpredictability of welding quality, the error is relatively high;

[0060] If only relying on ΔR, it is impossible to distinguish the difference in the initial size of the nugget (for example, the ΔR of a lack - of - fusion weld and a qualified solder joint may overlap).

[0061] R max directly reflects the maximum size at the moment of nugget formation, while ΔR reflects the shrinkage effect during the cooling process. The combination of the two can offset the measurement deviation of a single parameter.

[0062] Step S105: Determine the welding quality according to the nugget diameter.

[0063] If R max exceeds the preset range, directly determine that the quality is abnormal.

[0064] R max deviates from the R of a normal solder joint max range to qualitatively determine lack - of - fusion welds and spatter. When R max is greater than the normal R max range, it is determined as a lack - of - fusion weld; when it is less, it is determined as spatter.

[0065] Qualified solder joints need to meet (t is the thickness of the plate, unit: mm); ΔR is within the ±15% interval of the preset value.

[0066] The determination result (qualified / lack - of - fusion weld / spatter / cooling anomaly) is transmitted to the welding controller in real - time through the Modbus - TCP protocol;

[0067] The data packet is synchronously uploaded to the MES system, including parameters such as timestamp, R_max, ΔR, D, etc.

[0068] Please refer to Figure 2 As shown, the present application also provides a welding quality detection device, including:

[0069] A welding - torch voltage signal and current signal acquisition device, connected to the welding electrode;

[0070] A dual-channel signal processing module, connected to the acquisition device, for filtering and amplifying voltage signals and current signals;

[0071] A dual-channel A / D conversion module, connected to the signal processing module, for converting analog signals into digital signals;

[0072] A network communication module, connected to the A / D conversion module, for transmitting digitalized signals and realizing device interconnection.

[0073] Integrate a Hall voltage sensor and a Rogowski coil current sensor on the working surface of the welding torch electrode to synchronously capture voltage / current signals of the welding circuit at a sampling rate of 1 MHz.

[0074] Dual-channel signal processing module: Use a 50Hz power frequency and 1000HZ intermediate frequency notch filter to eliminate interference, and add a 10kHz low-pass filter to the voltage channel.

[0075] Programmable gain amplifier module: Implement a fixed gain of 100 times for voltage signals and an adaptive gain of 50 times for current signals.

[0076] Dual-channel A / D conversion module: A dual-channel 16-bit A / D converter performs synchronous digital processing at a sampling rate of 250kSPS. The voltage channel is directly connected to the two poles of the electrode, and the current channel eliminates common-mode noise through differential input; calculate R in real time max : Complete the freezing and capture of the resistance value within 5ms after the welding current is cut off.

[0077] ΔR dynamic detection: Automatically extract resistance characteristic values according to the preset time windows of T0-T1 and T2-T3.

[0078] Network communication module: Transmit the {R max , ΔR, D} data sequence including timestamps through the Modbus-TCP protocol, and share the quality determination result with the welding controller to achieve closed-loop control.

[0079] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art based on the disclosure of the present invention should fall within the protection scope of the present invention.

Claims

1. A welding quality detection method, characterized in that: include: Obtain the maximum resistance value of the weld nugget when the power is turned on for metal material welding; Obtaining an initial resistance value and a final resistance value of the nugget during the cooling stage; Calculating the difference between the initial resistance value and the final resistance value; determining a nugget diameter based on the maximum resistance value and the difference; The welding quality is determined based on the nugget diameter.

2. A welding quality detection method as claimed in claim 1, characterized in that: Obtaining the maximum resistance value of the weld nugget when the power is turned on for the metal material welding, including: measuring the maximum resistance value at the moment when the current is cut off at the last moment of the welding power-on stage; Acquiring the initial resistance value and the final resistance value of the weld core in the cooling stage includes: acquiring the initial resistance value through a T0-T1 time window, and acquiring the final resistance value through a T2-T3 time window.

3. A welding quality detection method as claimed in claim 2, characterized in that: Calculating the difference between the initial resistance value and the final resistance value includes: The arithmetic difference between the initial resistance value and the final resistance value, and there is a preset cooling time interval between the TO-T1 and T2-T3 windows.

4. A welding quality detection method as claimed in claim 1, characterized in that: Determining a diameter of a weld nugget based on the maximum resistance value and the difference value includes: The corresponding relationship between the difference and the diameter of the weld core is calibrated through a multi-factor welding experiment, and the multi-factors include: process parameters: welding current, welding pressure, power-on time, electrode size, and cooling water temperature and flow.

5. A welding quality detection method as claimed in claim 1, characterized in that: The welding quality is determined according to the nugget diameter, including: A resistance difference range standard for qualified solder joints is established, which covers process parameters, electrode diameter, and cooling water temperature variables.

6. A welding quality detection method as claimed in claim 1, characterized in that: To obtain the initial resistance value and the final resistance value: The intensity of the applied test current is on the order of 1 / 10 to 1 / 1000 of the welding current, and the single power-on time is controlled in the microsecond to millisecond level.

7. A welding quality detection device, characterized in that: include: A welding clamp voltage signal and current signal acquisition device connected to the upper and lower welding electrodes; A dual-channel signal processing module, connected to the acquisition device, for filtering and amplifying the voltage signal and the current signal; A dual-channel A / D conversion module, connected to the signal processing module, for converting analog signals into digital signals; The network communication module is connected to the A / D conversion module and is used to transmit digital signals and realize device interconnection.

8. A welding quality detection device as claimed in claim 7, characterized in that: The voltage channel and the current channel of the dual-channel A / D conversion module are respectively connected to the two working surfaces of the welding electrode.

9. A welding quality detection device as claimed in claim 7, characterized in that: The data transmitted by the network communication module includes a resistance measurement value sequence of R_max, R_initial and R_final.

10. A welding quality detection device as claimed in claim 7, characterized in that: The welding clamp voltage signal and current signal acquisition device synchronously acquires welding circuit signals at a sampling rate of 1 MHz, and the dual-channel A / D conversion module completes the maximum resistance value freezing calculation within 5 ms after the welding current is cut off.

Images