KR20230038365A - Method for detecting defect of spot welding employing ultrasonic sensor - Google Patents

Abstract

An embodiment relates to a method for detecting weld defects using an ultrasonic sensor. Specifically, the weld detection method uses an ultrasonic device to inspect the quality of a spot weld, and the device includes an ultrasonic sensor (probe), a flaw detector, and a PC. In this case, the ultrasonic probe uses water as a delay line, probes with a soft silicone membrane with improved durability, and transmits and receives ultrasonic signals just by applying a small amount of liquid. In addition, non-destructive inspection using ultrasonic waves is an inspection method that makes it easy to detect discontinuities inside an inspection object. There are several methods of transmitting ultrasonic waves, but here, quality evaluation is performed by examining a melted part of the spot weld using a reflection method. In one embodiment, good products and defective products are effectively determined based on the echo pulse characteristics of a liquid-applied ultrasonic signal. Therefore, through this, an embodiment provides a spot weld defect inspection and welding quality management method that enables comprehensive inspection, and does not destroy a welded part, directly inspects the welded part without pre- and post-processing processes, and inspects and evaluates the quality of all welded parts in real time, so the reliability of a resistance spot welding process is improved by applying the method directly to the field.

Description

Method for detecting defect of spot welding employing ultrasonic sensor}

The content disclosed herein relates to a technique for determining the quality of a spot weld, and more particularly, when monitoring the quality of a spot weld, collects and analyzes ultrasonic signals from the spot weld to determine whether or not the quality exists. .

Unless otherwise indicated herein, material described in this section is not prior art to the claims in this application, and inclusion in this section is not an admission that it is prior art.

In general, the number of resistant spot welding (hereinafter referred to as spot welding) processes required per car body is about 2,000 to 3,000 points. Although various welding methods such as adhesive bonding and friction stir welding (FSW) are applied, the use rate of spot welding tends to be maintained at least 2,000 points in terms of automation.

In addition, the use rate of advanced high strength steel (AHSS) plates and galvanized steel materials with high specific strength is increasing in order to reduce the weight of the vehicle body and improve corrosion resistance. However, the high alloy composition ratio of high-strength steel sheet is also the cause of many welding defects compared to general low-carbon steel resistance spot welding. In addition, the zinc (Zn) layer plated to improve corrosion resistance accelerates the change in the tip diameter of the spot welding tip and acts as a cause of lowering the current density.

Therefore, it is necessary to perform a non-destructive inspection of the entire spot welded part applied during vehicle manufacturing and to control the welding quality according to the change in tip diameter (inconsistent weldability due to the increase in welding spots).

In particular, welding is a technique of joining two metals by melting the metal and rearranging the crystal structure. Therefore, the shape of the fusion zone, the degree of connection of the weld zone, and the shape of the magnetic field are modified according to the crystal structure of the metal, the shape of the texture, the welding temperature, the pressing force, etc., and the quality of the weld zone can be inspected using these characteristics. Therefore, there is a need for an inspection method that meets field requirements for a fast and highly reliable spot weld inspection using the characteristics of the spot weld as described above.

And, on the other hand, as a method of evaluating the soundness of the spot weld, visual inspection to visually observe the appearance of the weld, destructive test to inspect the weld by artificially twisting it or destroying it using a screwdriver or chisel, and ultrasonic waves An ultrasound scan is used.

In particular, among these methods, the ultrasonic inspection method is a highly reliable non-destructive inspection method and is widely used in various fields.

By the way, this ultrasonic inspection method analyzes the reflected signal after transmitting ultrasonic waves to the welded part to determine the amount or negative of the welded part. influence the test results.

In addition, the prior art literature in this background is only to the extent that the following patent literature comes out.

(Patent Document 1) KR1020020020672 A

For reference, the technology of Patent Document 1 relates to a spot welding quality evaluation method. In order to monitor the quality of a welded part, the representative welding conditions such as welding current, voltage, pressure, and dynamic resistance are measured and the welding quality is known according to the variation. It is a technology that allows

The disclosed content is a welded part using an ultrasonic sensor that can be applied directly to the field to improve the reliability of the resistance point welding process by directly inspecting and evaluating the quality of the welded part in real time without destroying the welded part and without a post-processing process. It is intended to provide a defect detection method.

A welding defect detection method using an ultrasonic sensor according to an embodiment,

An ultrasonic device for quality inspection of a spot weld is used, and this device includes an ultrasonic sensor (probe), a flaw detector, and a PC.

In this case, the ultrasonic transducer uses water as a delay line and uses a soft silicon membrane with improved durability to transmit and receive ultrasonic signals only by applying a small amount of liquid.

In addition, nondestructive inspection by ultrasonic waves is an inspection method in which it is easy to detect discontinuities inside the inspection object, and there are various methods of transmitting ultrasonic waves, but here, the quality evaluation is performed by inspecting the molten part of the spot welding part by the reflection method.

And, at this time, it is characterized in that good products and defective products are effectively determined based on the echo pulse characteristics of the liquid application type ultrasonic signal.

Specifically, such a weld defect detection method,

In the case of spot welding the welding target and monitoring the quality of the spot weld, in the method of determining the quality by collecting and inspecting the ultrasonic wave of the spot weld in the management information processing device,

In the case of determining the quality of the spot weld, a first step of transmitting and receiving ultrasonic signals by applying a small amount of liquid from an ultrasonic sensor having a transducer, a water column for a delay line, and a soft silicon membrane ;

a second step of extracting echo pulse characteristics of the liquid application type ultrasonic signal transmitted and received in the first step;

a third step of comparing the echo pulse characteristics of the liquid application type ultrasonic signal with the echo pulse characteristics for each set good/defective product to determine the quality of the spot welded part; contains,

The third step,

a) As a result of the comparison, when the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set good echo pulse characteristics (the amplitude of the subsequent echo pulse decreases relatively faster than the reference speed), the quality of the spot weld is good. judged by,

b) When the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set first defective echo pulse characteristics (an echo pulse signal smaller than the reference size is received between normal echo pulses), the quality of the spot weld is determined by having a smaller nugget diameter. judge the state,

c) When the echo pulse characteristic of the liquid application type ultrasonic signal corresponds to the set second echo pulse characteristic (the subsequent echo pulse appears long), the quality of the spot welding part is judged to be a stick welding state;

d) When the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set third defective product echo pulse characteristics (echo pulses at short intervals appear long), the quality of the spot welding part is set to a loose state, that is, the welding is It is characterized by judging that it is not.

According to the embodiments, to provide a spot weld defect inspection and welding quality control method capable of total inspection, without destroying the weld, directly inspecting the quality of the weld in real time without prior and subsequent processing, and evaluating the quality of the weld in real time. It is directly applied to improve the reliability of the resistance spot welding process.

1 is a view for conceptually explaining a method for detecting defects in a welded part using an ultrasonic sensor according to an embodiment;
Figure 2 is a view showing a system as a whole to which a welding defect detection method using an ultrasonic sensor according to an embodiment is applied
3 is a block diagram showing the configuration of a management information processing device to which a welding defect detection method using an ultrasonic sensor according to an embodiment is applied.
Figure 4 is a flow chart showing the operation of the weld defect detection method using an ultrasonic sensor according to an embodiment in order

1 is a diagram for conceptually explaining a method for detecting defects in a welding part using an ultrasonic sensor according to an embodiment.

As shown in FIG. 1, a welding defect detection method using an ultrasonic sensor of an embodiment uses an ultrasonic device (Ultrasonic test) for quality inspection of a spot weld, which includes an ultrasonic sensor (transducer) and a flaw detector and includes PC.

In this case, the welding defect detection method according to an embodiment is a method in which an ultrasonic probe uses water as a delay line and transmits and receives ultrasonic signals only by applying a small amount of liquid by probe with a soft silicon membrane.

In addition, the existing membrane-type ultrasonic transducer has a membrane thickness of about 0.1 mm and is not suitable for automatic inspection due to poor durability. Therefore, a silicon membrane with improved durability is provided.

In addition, even when using a membrane-type ultrasonic transducer, there is signal attenuation due to an air gap with the inspection surface, so a small amount of liquid must be applied to the inspection surface, and a post-processing process that must be removed after application is required.

And, at this time, by selecting and combining highly volatile liquids, it is possible to provide a liquid medium for automatic inspection and a liquid ejection device that automatically volatilizes after automatic inspection.

On the other hand, such a welding defect detection method is an inspection method in which non-destructive inspection by ultrasonic waves is an inspection method in which it is easy to detect discontinuities inside the inspection object, and there are various methods of transmitting ultrasonic waves. By doing so, quality evaluation is performed.

In this case, the echo pulse detected by the ultrasonic sensor has a different shape depending on the quality of the spot welded part.

For example, a spot welded part of a good product has high attenuation characteristics of ultrasonic waves, so that subsequent echo pulses decrease relatively quickly, but a spot welded part of a defective product has a small echo between echo pulses, or repeats long echo pulses with low attenuation characteristics, or echo pulses are It appears in the form of a narrow gap.

Thus, an ultrasound examination quality evaluation algorithm according to an embodiment is provided based on the echo pulse characteristics.

2 is a diagram showing a system as a whole to which a method for detecting weld defects using an ultrasonic sensor according to an embodiment is applied.

As shown in Figure 2, the system of one embodiment includes a 6-DOF multi-joint industrial inspection robot system (including a management information processing device) and an inspection robot end device for multi-sensing.

Additionally, the system according to an embodiment provides various additional services through external linkage by connecting to the management information processing device, and includes a troubleshooting information processing device (not shown).

And, in this case, the system connects each device to each other through its own network, and, for example, connects to either serial (RS232, RS485) or wireless (LoRA, RF, BT, BLE) through a network.

The 6-DOF articulated industrial inspection robot system (including management information processing device) can take any position and posture in a 3-dimensional space in a 6-degree of freedom articulated industrial robot, so it can be used for car body frames, doors, and doors. Spot welds are inspected in response to various structures and shapes, such as And, in this case, joint control of the inspection robot is premised on receiving coordinates from the spot welding robot, but position correction can be performed after teaching by direct teaching in case of emergency. In addition, when the ultrasonic signal of the spot welding part is received from the ultrasonic device, the management information processing device additionally determines the quality of the spot welding part from the welding part defect detection algorithm according to an embodiment, thereby improving the reliability of the spot welding process. .

The inspection robot end device is attached with a device for multiple sensing, and to this device, small linear actuators are attached at intervals of 120° in the circumferential direction, and to each linear actuator, a device such as an optical camera for visual inspection and an ultrasonic inspection Fix the ultrasonic sensor (transducer) and magnetic sensor for magnetic leakage test. And, in this case, the inspection surface of each sensor is located on the same concentric circle at the center of the device, and each sensor makes it easy to control the inspection position through the translational motion of the linear actuator and the rotational motion of the end joint of the inspection robot. In addition, a force sensor is applied between the device and the distal joint of the robot to detect the contact pressure of the ultrasonic probe during ultrasonic inspection and maintain an appropriate pressure.

3 is a block diagram showing the configuration of a management information processing device to which a method for detecting weld defects using an ultrasonic sensor according to an embodiment is applied.

As shown in FIG. 3, the management information processing device according to an embodiment includes an I/F unit 301 connected to an ultrasonic device and a main processing unit 302 that performs a quality inspection using ultrasonic signals of the ultrasonic device; database 303.

Additionally, the management information processing device 300 according to an embodiment includes a key signal input unit 304 receiving various setting information according to user key manipulation and a display unit 305 displaying welding defect monitoring information and the like.

The I/F unit 301 connects the ultrasonic device with a small amount of liquid application type ultrasonic device to collect ultrasonic signals of a spot welding part desired by a manager. And, at this time, additionally, the I/F unit 301 receives a manager control signal under the control of the main processing unit 302, for example, a power-on signal of the ultrasonic device when the quality inspection of the spot welding part is started. It is also provided as a device.

The main processing unit 302 improves the reliability of the spot welding process by determining the quality of the spot weld from the weld defect detection algorithm according to an embodiment when the ultrasonic signal of the spot weld is received from the ultrasonic device. In this case, the welding defect detection algorithm evaluates quality using the echo pulse characteristics of the ultrasonic signal, that is, the ultrasonic signal generated by the liquid application type ultrasonic device.

The database 303 stores actual data such as the registration information of each device and the ultrasonic signal of the spot welding part, so that previous data can be accumulated and used when determining the quality of the spot welding part.

4 is a flow chart illustrating operations of a method for detecting defects in a welded part using an ultrasonic sensor according to an embodiment in order.

As shown in FIG. 4, in the method for detecting defects in a welding part according to an embodiment, when the quality of a spot welding part is monitored by first spot-welding a welding target, the management information processing device collects and inspects ultrasonic waves of the spot welding part to check the quality. The method of determination is premised (same as the existing method).

In this state, when the quality of the spot weld is determined according to an embodiment, a small amount of liquid is applied only from an ultrasonic sensor having a water column for a transducer, a delay line, and a soft silicon membrane to detect to transmit and receive ultrasonic signals.

Then, in one embodiment, in particular, echo pulse characteristics of the liquid application type ultrasonic signal transmitted and received in this way are extracted.

Therefore, the quality of the spot welding part is determined by comparing the echo pulse characteristics of the liquid application type ultrasonic signal with the echo pulse characteristics for each set good/defective product.

Specifically, this quality judgment is as follows.

a) First, as a result of the comparison, when the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set good echo pulse characteristics (the amplitude of the subsequent echo pulse decreases relatively faster than the reference speed), the quality of the spot weld is good. judge the state

b) When the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set first defective echo pulse characteristics (an echo pulse signal smaller than the standard size is received between normal echo pulses), the quality of the spot weld is determined as the nugget diameter judged by this small state.

c) In addition, when the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set second irregular echo pulse characteristics (the subsequent echo pulse appears long), the quality of the spot welding portion is determined to be a stick welding state.

d) When the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set third defective product echo pulse characteristics (echo pulses at short intervals appear long), the quality of the spot weld is set to a loose state, that is, It is judged as non-welded.

Therefore, through this, the reliability of the resistance spot welding process is improved by directly applying it to the field by directly inspecting and evaluating the quality of the welded part in real time without destroying the welded part and without a post-processing process.

As described above, one embodiment uses an ultrasonic device for quality inspection of a spot weld, and this device includes an ultrasonic sensor (probe), a flaw detector, and a PC.

In this case, the ultrasonic transducer uses water as a delay line and uses a soft silicon membrane with improved durability to transmit and receive ultrasonic signals only by applying a small amount of liquid.

In addition, nondestructive inspection by ultrasonic waves is an inspection method in which it is easy to detect discontinuities inside the inspection object, and there are various methods of transmitting ultrasonic waves, but here, the quality evaluation is performed by inspecting the molten part of the spot welding part by the reflection method.

At this time, good products and defective products are effectively determined based on the echo pulse characteristics of the liquid coating type ultrasonic signal.

Therefore, through this, one embodiment improves the reliability of the resistance spot welding process by directly applying it to the field by directly inspecting and evaluating the quality of the welded part in real time without destroying the welded part and without a pre-processing process.

On the other hand, in addition to this, in the case of providing various types of information in this way, the method of detecting defects in welding parts keeps databases consistent with each other, thereby providing services quickly and conveniently.

To this end, the management information processing device performs the following operations.

a) First, the ultrasonic device and a table storing device registration information and data are equally provided to each other, and matching relationships with the tables are previously set and registered.

b) Therefore, when information in the tables is mutually changed, the tables are synchronized according to the matching relationship.

c) And, when synchronizing the tables, databases are matched by diversifying information for each data type for a number of different equipment types and manager device types.

On the other hand, additionally, when providing various information to the management side, this method of detecting weld defects ensures real-time connection to manager terminals in the vicinity, so that the information is quickly and easily transmitted to the manager.

To this end, the management information processing device performs the following operations.

a) First, when the management information processing device communicates with the registration manager terminal, it first checks whether or not the registration local communication network is connected. Connect as an admin public account.

b) As a result of the check, if the local communication network is not connected, whether or not the registered wireless communication network is connected is secondarily checked, and if the wireless communication network is connected as a result of the check, the individual IP address is connected.

c) As a result of the check, if the wireless communication network is not connected, the connection is made using the terminal identification number of the registered mobile communication network, so that the connection with the manager terminal is secured.

On the other hand, in case of real-time connection with the administrator terminal, the IP table is used to monitor the registered IP and monitor (or log) the access of an unauthorized person for the security of the connection.

a) Specifically, for this purpose, an IP table in which a common manager account of the local communication network and an individual IP address of the wireless communication network are registered is configured in advance.

b) And, when the alarm is provided to the manager terminal, a HELLO message of the corresponding communication network is transmitted to extract the IP address of the next hop switch in the response result.

c) Next, the same switch IP address as the next hop switch IP address is checked in the switch neighbor connection relationship list.

d) As a result of the above check, if there is a switch IP address identical to the next hop switch IP address, it is checked whether the corresponding manager public account or individual IP address is also present in the IP table, so whether an unauthorized person is connected is checked.

e) As a result of the above check, if the corresponding manager common account or individual IP address is also present in the IP table, the JOIN/PRUNE message is sent, so the corresponding communication network is connected.

On the other hand, as a form different from these, this method of detecting defects in welding parts analyzes the cause of failure for each device in the case of monitoring in this way, so that maintenance targets and parts are quickly and smoothly maintained.

To this end, the management information processing device performs the following operations.

First, when the management information processing device performs a failure diagnosis for each device, an actual failure cause is estimated because device components substantially affecting the current failure are detected from the following failure cause analysis format.

At this time, the failure cause analysis format is performed as follows.

a) First, when detecting device components, the failure cause analysis format calculates respective influences from basic device characteristics for each of a plurality of different device components in order of high failure rates.

For example, when an abnormality occurs in an ultrasonic device and the cause of a failure is analyzed, the basic housing, line equipment, and peripheral devices are first calculated in order.

b) And, the degree of influence (Zt) of the device components is calculated according to the following [Equation 1].

[Equation 1]

Zt = η1Zt-1 + η2Zt-2 + ... + ηpZt-p + ιt - ι1κt-1 - ... - ιqκt-q

(Where Zt is the overall current influence of the device component (t), Zt-n is the current influence of each major state factor (t-1, t-2, ... , t-p) of the device component (t) , η is the basic influence correlation coefficient for each major state factor, κ is the error between the moving average influence for each major state factor and the current influence (Zt-n), ι is the basic error correlation coefficient for each major state factor)

For example, in the case of a basic housing, the main condition factors are a surface condition, a color condition (related to deformation), a friction (or abrasion) condition, a temperature condition, and the like.

So, for the influence of this specific device component, for example, in the case of a basic housing, the total sum of the current influence of the surface state, etc., and the average value, that is, the influence of the moving average influence and the error between the current influence and the influence of the main state Total sum for each factor. Then, the result value is obtained by adding the respective summation results again.

At this time, the degree of influence is, for example, the basic correlation degree of the surface state, that is, the default value and weight (see below) for how much it basically affects when diagnosing the surface state, and the effect proportional to the current surface state multiply by degrees

Therefore, through this, when the degree of influence (Zt) is greater than the set reference value, it is determined that the corresponding device component has an effect on the current abnormality, and thus the cause of the failure is identified.

In addition, in this case, by discriminating the cause of the failure using the order of high failure probability, it is also possible to prioritize rapid repair for the cause of the failure that has a great influence.

c) Next, the aforementioned weight, that is, the basic influence correlation coefficient includes different weights in proportion to the degree of basic influence correlation for each main state factor.

For example, in the case of the basic screen as described above, the highest weight is given to the surface state, and the next largest value is given to the friction (or abrasion) state and the temperature state in order. Then, the next largest weight is assigned to the color state (transformation related).

d) Next, the moving average range of [Equation 1] is determined as follows.

That is, when the basic wear of the device component is less than the reference value, it is reduced by the moving average interval value calculated according to [Equation 2] from the standard moving average interval value, and when it is greater than the reference value, calculated according to [Equation 2] Increase by the value of the moving average interval.

[Equation 2]

Moving average interval = [{|current wear - set wear rate|/unit wear difference value} ㅧ unit moving average interval]

Therefore, through this, the moving average section is set differently according to the degree of wear for each different device component.

On the other hand, in addition to this, when the ultrasonic signal is analyzed in this way, the ultrasonic signal is automatically analyzed from the following configuration so that the manager conveniently and effectively detects defects related to the weld.

To this end, this weld defect detection method has the following weld defect detection model, and this configuration is as follows.

a) First, in the case of analyzing the ultrasonic signal, the ultrasonic signal is classified and learned according to the time zone information for performing the work using ambient conditions, for example, temperature and humidity, dust level, vibration, etc. for each of a number of different places, and also stabilized ultrasonic signals Define a model that uses In addition, in this case, it is classified in a little more detail by welding object, material, size, work state/circumstance, etc.

In this case, the ultrasonic signal is converted into a stabilized signal so that a desired value can be obtained.

For example, when an ultrasonic signal is received, each section of the reflected ultrasonic signal is first linearized using spline interpolation.

Next, the average rate of change between the minimum and maximum values for each section of the first-order linearization is calculated.

In addition, a plurality of average change rate values are obtained by applying a predetermined weight differently according to the difference in the average rate of change.

Next, a plurality of moving average values are obtained by performing a moving average on the plurality of average change rate values.

Thus, a stabilized ultrasonic signal is obtained by quadratic linearizing each curve section to which a plurality of moving averages are applied.

At this time, the point for acquiring the plurality of average rate of change determines a predetermined weight according to the difference in the average rate of change, and applies the weight to the average rate of change to obtain the stabilized ultrasound signal.

b) Next, a dataset representing characteristics according to state information and welding work time zone information around a plurality of different places is extracted.

c) Then, the data set is attributed by reflecting a plurality of different places and time zones, surrounding conditions, and situation information, for example, work situation information and surrounding situation information.

d) Then, based on the attribution information, attributes of data according to state information around each place and welding time zone information are determined for each learning model.

e) Next, normalize the decision information.

f) So, based on the normalization information, data according to the state information around each place and welding work time zone information is set for each learning model. So, in order to be able to grasp whether the ultrasonic signal is normal through this, the ultrasonic signal is normal or not as an independent variable, and various information and work information about the welding target according to the status information around each place and the welding work time zone information are set as dependent variables respectively.

g) Then, create this setting information as learning and training data.

h) Therefore, a deep learning-based weld defect detection model is generated from the generated information.

300: management information processing device
301: I/F unit 302: main processing unit
303: database 304: key signal input unit
305: display unit

Claims (4)

In the case of spot welding the welding target and monitoring the quality of the spot weld, in the method of determining the quality by collecting and inspecting the ultrasonic wave of the spot weld in the management information processing device,
In the case of determining the quality of the spot weld, a first step of transmitting and receiving ultrasonic signals by applying a small amount of liquid from an ultrasonic sensor having a transducer, a water column for a delay line, and a soft silicon membrane ;
a second step of extracting echo pulse characteristics of the liquid application type ultrasonic signal transmitted and received in the first step; and
a third step of comparing the echo pulse characteristics of the liquid application type ultrasonic signal with the echo pulse characteristics for each set good/defective product to determine the quality of the spot welded part; contains,

The third step,
a) As a result of the comparison, when the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set good echo pulse characteristics (the amplitude of the subsequent echo pulse decreases relatively faster than the reference speed), the quality of the spot weld is good. judged by,
b) When the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set first defective echo pulse characteristics (an echo pulse signal smaller than the reference size is received between normal echo pulses), the quality of the spot weld is determined by having a smaller nugget diameter. judge the state,
c) When the echo pulse characteristic of the liquid application type ultrasonic signal corresponds to the set second echo pulse characteristic (the subsequent echo pulse appears long), the quality of the spot welding part is judged to be a stick welding state;
d) if the echo pulse characteristics of the liquid application type ultrasonic signal correspond to the set third defective product echo pulse characteristics (echo pulses at short intervals appear long), determining the quality of the spot welded part as a loose state; Welding defect detection method using an ultrasonic sensor, characterized in that. The method of claim 1,
The management information processing device
a) The ultrasonic sensor and the table storing the device registration information/data are equally provided to each other, and a matching relationship for the table is set and registered in advance,
b) when information in the table is changed with each other, the tables are synchronized according to the matching relationship;
c) When synchronizing the table, matching databases by diversifying information for each data type for a plurality of different equipment types and manager device types; Welding defect detection method using an ultrasonic sensor, characterized in that. The method of claim 2,
The management information processing device
a) Provides quality information of the spot welding monitored by communicating with the registration manager terminal, and when providing the quality information of the spot welding, first checks whether or not the registration local communication network is connected, and as a result of the check, the local When the communication network is connected, it is connected as a setting manager common account corresponding to different management work locations;
b) As a result of the check, if the local communication network is not connected, secondarily check whether the registered wireless communication network is connected, and if the wireless communication network is connected as a result of the check, connect to an individual IP address,
c) as a result of the check, if the wireless communication network is not connected, it is connected with the terminal identification number of the registered mobile communication network, thus securing a connection with the manager terminal; Welding defect detection method using an ultrasonic sensor, characterized in that. The method of claim 3,
The management information processing device
a) pre-configuring an IP table in which an administrator public account of the local communication network and an individual IP address of the wireless communication network are registered;
b) When an alarm is provided to the manager terminal, a HELLO message of the corresponding communication network is transmitted to extract the IP address of the next hop switch in the response result;
c) confirming the same switch IP address as the next hop switch IP address in the switch neighbor connection relationship list;
d) As a result of the check, if there is a switch IP address identical to the next hop switch IP address, it is checked whether the corresponding administrator public account or individual IP address is also present in the IP table, so it is checked whether an unauthorized person is connected,
e) As a result of the confirmation, if the corresponding manager public account or individual IP address is also present in the IP table, a JOIN/PRUNE message is sent, so connecting to the corresponding communication network; Welding defect detection method using an ultrasonic sensor, characterized in that.

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