KR20140028201A - Spot welding monitoring system and its method - Google Patents

Abstract

The present invention relates to a system and a method for monitoring a spot welding process and, more specifically, to a system and a method for monitoring a spot welding process capable of using welding data to increase quality by storing the welding data including three-dimensional position information, voltage, and current at each welding point in the spot welding process using a robot. According to the present invention, the system for monitoring a spot welding process comprises: the spot welding robot to spot weld a welded object by connecting lower and upper arms to a robot body and a stud gun to the front end of the upper arm; a robot controller to control the operation of the spot welding robot and collecting the three-dimensional position information of the stud gun on the spot welding process; and a monitoring device to receive the three-dimensional position information of the stud gun from the robot controller, measuring and storing the voltage and current of the stud gun as measured welding data, and comparing the reference welding data stored itself with the measured welding data to determine whether or not the spot welding process is abnormal. [Reference numerals] (2) Robot controller; (3) Monitoring device; (AA) Voltage and current; (BB,CC) Position information

Description

Spot welding monitoring system and method {SPOT WELDING MONITORING SYSTEM AND ITS METHOD}

The present invention relates to a spot welding monitoring system and method, and more particularly, in spot welding using a robot, welding data including three-dimensional position information, voltage, and current for each welding point is stored to improve quality. The present invention relates to a spot welding monitoring system and a method thereof.

In general, welding is a metallurgical joining of a metal member by an operation such as heating / pressing. The welding is performed by locally heating / melting joints of both metal members to be joined to melt the filler material and joining them by local casting. fusion welding, and a solder material, which is a nonferrous alloy filler material with a much lower melting point than the base metal to be joined by pressing welding, which is a method of heating the joint to a suitable temperature and applying mechanical pressure thereto, to melt and add And solder joints that achieve the purpose of joining by utilizing the intermolecular attraction during solidification of the molten lead material.

This welding process is able to weld evenly and safe welding technology. Today, the automatic welding device which performs the welding process automatically according to the development of robot and automation technology is widely used in the production line. Giving.

In particular, in the production of large quantities of certain products such as automobile production lines, the welding time is very short compared to other welding, and the working speed is fast, and the heating range is narrow, so there is little residual stress or deformation. This is mainly used.

This spot welding is a welding which performs point joining of a plate without joining a plate through a life preserver like a rivet joint by using the heat generated by the electrical resistance to cause melting of the contact portion and joining the pressure together.

In order to obtain a good welding result in such spot welding, the pressing force, energization time, and current value should be appropriate.

In most cases, the operator decides the tip dressing replacement cycle as a rough rule of thumb, and when there are many welding spots (spots) in one product, it is common to accidentally fail to perform welding.

Conventionally, the spot welding was judged with an abnormal signal from the welder, depending on the number of spots or depending on the setting value of the welder itself.

However, in the method of counting the number of RBIs, when an abnormality occurs during welding, the worker counts the same pointer twice or hits the RBI due to an operation such as performing spot welding again or moving the robot to another point in the teaching mode. There is a possibility of missing without counting.

In addition, when determining whether the welding is abnormal by the signal of the welding machine itself, it is determined by the current and voltage applied to the primary side of the transformer, there is a problem that the accuracy is lowered because the difference occurs with the actual welding current.

Registration No. 20-0312742 (Notice date May 16, 2003) Registration No. 10-0504926 (Announcement date August 01, 2005)

The present invention has been made in order to solve the above problems, it is determined that the welding is completed with the welding at the position (point) to be actually welded, can actually determine how much voltage and current is energized for The present invention aims to provide a spot welding monitoring system and method capable of individual management by welding point.

Spot welding monitoring system according to the present invention for achieving the above object, a spot welding robot for jointing the lower arm and the upper arm to the robot body, the stud gun is connected to the tip of the upper arm spot welding the welding target;

A robot controller which controls the operation of the annoying spot welding robot and collects three-dimensional position information of the stud gun during the spot welding; And

The robot controller receives three-dimensional positional information of the stud gun, measures the voltage and current of the stud gun and stores the measured welding data, and compares the stored reference welding data with the measured welding data to determine whether the spot welding is abnormal (bad). A monitoring device for determining;

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In addition, the monitoring device is characterized in that to store the measurement welding data for each welding point, and includes the welding time in the measurement welding data.

In addition, the monitoring device is characterized in that for measuring the voltage and current of the secondary side of the transformer for supplying power to the stud gun.

In addition, the spot welding monitoring method according to the present invention, the step of storing the reference welding data including the three-dimensional position information of the stud gun of the spot welding robot, the secondary side voltage and current of the stud gun in the monitoring device for each welding point;

Receiving actual three-dimensional positional information of the stud gun during spot welding from a robot controller, and receiving a digitally converted value by measuring the actual voltage and current of the transformer secondary side supplied to the stud gun;

Storing the measurement welding data including the three-dimensional position information and the digitally converted voltage and current for each welding point;

Determining whether spot welding is abnormal (defective) by comparing reference welding data and measured welding data for each welding point; And

Outputting an abnormal signal through an output unit including a display, a speaker, a buzzer, and an LED when it is determined that the spot welding is abnormal;

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According to the above-mentioned means for solving the problem, it is possible to read the current coordinate value of the robot to know where the welding is made, and to analyze the welding characteristics at the corresponding position with the secondary voltage and current of the transformer to analyze the reliability of the welding. It is possible to improve welding quality and customer reliability by managing welding data for each point based on coordinate values.

1 is a schematic diagram of a spot welding monitoring system according to the present invention.
2 is a block diagram of the monitoring apparatus shown in FIG.
3 is a flowchart of a spot welding monitoring method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

It is to be noted that the same components of the drawings are denoted by the same reference numerals and symbols as possible even if they are shown in different drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Also, when a part is referred to as "including " an element, it does not exclude other elements unless specifically stated otherwise.

1 is a schematic diagram of a spot welding monitoring system according to the present invention.

As shown, the spot welding monitoring system includes a spot welding robot 1, a robot controller 2, and a monitoring device 3.

In the spot welding robot 1, the lower arm 11 and the upper arm 12 are jointly connected to the robot main body 17 on the base 10 mounted on the floor, and two welds are connected to the tip of the upper arm 12. A finger, that is, a stud gun 13 is connected, while the servo motor 16 is provided on the stud gun 13 and the welding tips 14 and 15 are attached to the top and bottom of the stud gun 13, respectively. to be.

Each of the arms 11 and 12 can be rotated through a plurality of axes so that the finger of the upper arm 12 can move in three dimensions to pick up the metal member to be welded and spot weld.

The operation of the spot welding robot 1 operated in this way is dependent on the program input to the robot controller 2, which is made by the basic coordinate system.

That is, the robot controller 2 controls the spot welding robot 1 by a control signal and a set program by a user operation, and the spot welding robot 1 operates by the control signal of the robot controller 2 and is internally controlled. A mechanical device is incorporated in the apparatus, and a stud gun 13 is provided at the tip to weld the metal member to be welded.

At this time, the robot controller 2 receives the three-dimensional position information (coordinate value) of the stud gun 13 from the spot welding robot 1 and transmits it to the monitoring device 3 by wireless communication.

The stud gun 13 is connected to the secondary side of the transformer (not shown) for converting and outputting the voltage by the winding ratio of the primary side and the secondary side to operate as a power output from the transformer, the monitoring device 3 is The actual voltage and current of the secondary side of the transformer supplying power to the stud gun 13 are measured.

The monitoring apparatus 3 stores and manages welding data such as three-dimensional position information, voltage, and current for each welding point.

In this case, the monitoring device 3 may include a timer therein and set the welding time to a time at which a voltage and a current of a predetermined magnitude or more are detected, and include the same in the welding data.

In addition, the monitoring device compares the actual measured values (three-dimensional position information and voltage and current, etc.) with a preset reference value (three-dimensional position information, voltage and current, etc.) to determine whether the welding is abnormal (defect), If it is determined that the abnormality (bad), the abnormal signal is output by the screen, sound, lighting (or flashing), etc. to inform the surrounding users.

2 is a block diagram of the monitoring apparatus shown in FIG.

As shown, the monitoring device 3 includes a voltage sensor 31 and a current sensor 32, a wireless communication unit 33, an A / D converter 34, an input unit 35, a memory 36, and a microprocessor ( 37) and the output unit 38 is configured.

The voltage sensor 31 and the current sensor 32 are provided in the stud gun 13 of the spot welding robot 1 to measure the secondary voltage and current of the transformer for supplying power to the stud gun 13 to measure the A / A. Output to the D converter 34.

In this case, the output line and the current sensor are connected to each other by passing one of the output lines on the secondary side of the transformer through the measurement hall in the current sensor. There are generally two types of CT (Current Transformer) and Hall Current sensor, and the current sensor 32 The current value measured through) is output to the microprocessor 37 through the A / D converter 34.

In the case of the voltage sensor 31, the voltage value measured by the voltage sensor 31 by connecting the voltage sensors 31 in parallel to both ends of the transformer is transferred to the microprocessor 37 through the A / D converter 34. Is output.

The A / D converter 34 converts the analog voltage and current measured by the voltage sensor 31 and the current sensor 32 into digital voltage and current to facilitate data management and comparison.

The A / D converter 34 may be separately connected to the voltage sensor 31 and the current sensor 32 to convert the voltage and the current into digital and then output the digital signal to the microprocessor 37.

The wireless communication unit 33 wirelessly receives the three-dimensional position information (coordinate value) from the robot controller 2 and outputs it to the microprocessor 37.

The input unit 35 may set reference values by inputting reference values for three-dimensional position information, voltage, current, time, etc. for each welding point by an external input of the user.

The microprocessor 37 stores various reference values input by the input unit 35 in the memory 36 and provides the 3D position information received through the wireless communication unit 33 and the A / D converter 34. The received voltage and current are stored in the memory 36 to store and manage welding data for each welding point.

That is, the three-dimensional position information for each welding point and the voltage, current, time, etc. in the position is stored and managed.

The memory 36 stores not only reference values and measured values, but also programs necessary for overall control and execution of the monitoring device 3.

The microprocessor 37 analyzes the welding state by comparing the reference value with the measured value, and determines that the welding abnormality (defect) when the measured value is out of the reference value.

In the case of the welding abnormality (defect), the abnormality signal is output to the output unit 38 so that the user can be notified of the abnormality.

The output unit 38 may include a display indicating that there is an abnormality under the control of the microprocessor 37, a speaker or buzzer indicating a sound, and an LED indicating lighting or flashing of light.

In addition, the output unit 38 may display a reference value input by the input unit 35 or a measured value measured on the display screen.

3 is a flowchart of a spot welding monitoring method according to the present invention.

As shown in the drawing, when a user inputs reference values (reference welding data) for three-dimensional position information, voltage, and current for each welding point through the input unit 35 provided in the monitoring apparatus 3, the microprocessor 37 may input the reference values. The input reference value is confirmed and stored in the memory 36 (S302).

When spot welding the welding target using the spot welding robot 1, the robot controller 2 receives the three-dimensional position information (coordinate value) of the stud gun 13 from the spot welding robot 1 and receives the radio communication unit ( 33, receiving the three-dimensional positional information of the actual stud gun 13 during welding in the monitoring device (3) (S304).

At this time, the voltage sensor 31 and the current sensor 32 measures the voltage and current of the transformer secondary side supplied to the stud gun 13 and transmits it to the A / D converter 34 (S306).

The A / D converter 34 converts the voltage value and the current value obtained through the voltage sensor 31 and the current sensor 32 into digital values and provides them to the microprocessor 37 (S308).

The microprocessor 37 includes three-dimensional positional information of the actual stud gun 13 input through the wireless communication unit 33 and a digital voltage and a current of the secondary side of the transformer input through the A / D converter 34. The measured value (measurement welding data) is stored in the memory 36 for each welding point to be managed (S310).

In addition, the microprocessor 37 analyzes the welding state by comparing the reference value (reference welding data) and the measurement value (measurement welding data) for each welding point (S312), and the welding abnormality (defect) when the measured value deviates from the reference value. It is determined whether or not (S314).

When it is determined that the welding is abnormal, the abnormal signal is output through the output unit 38 to inform that there is an abnormality in the spot welding (S316).

If spot welding continues by the spot welding robot after the abnormal signal output or after determining that there is no abnormality (S318), the process returns to the step S304 and the above steps are repeated until the spot welding is completed.

1: Spot welding robot 2: Robot controller
3: monitoring device 13: stud gun
31: voltage sensor 32: current sensor
33: wireless communication unit 34: A / D converter

Claims (4)

A spot welding robot jointly connected to a lower arm and an upper arm to a robot body, and a stud gun connected to a tip of the upper arm to spot weld a welding target;
A robot controller which controls the operation of the annoying spot welding robot and collects three-dimensional position information of the stud gun during the spot welding; And
The robot controller receives three-dimensional positional information of the stud gun, measures the voltage and current of the stud gun and stores the measured welding data, and compares the stored reference welding data with the measured welding data to determine whether the spot welding is abnormal (bad). A monitoring device for determining;
Spot welding monitoring system comprising a. The method of claim 1,
The monitoring device stores the spot welding data for each welding point, the spot welding monitoring system comprising a welding time in the measurement welding data. The method of claim 1,
The monitoring device spot welding monitoring system, characterized in that for measuring the voltage and current of the secondary side of the transformer for supplying power to the stud gun. Storing reference welding data including the three-dimensional position information of the stud gun of the spot welding robot, the secondary side voltage and the current of the stud gun in the monitoring apparatus for each welding point;
Receiving actual three-dimensional positional information of the stud gun during spot welding from a robot controller, and receiving a digitally converted value by measuring the actual voltage and current of the transformer secondary side supplied to the stud gun;
Storing the measurement welding data including the three-dimensional position information and the digitally converted voltage and current for each welding point;
Determining whether spot welding is abnormal (defective) by comparing reference welding data and measured welding data for each welding point; And
Outputting an abnormal signal through an output unit including a display, a speaker, a buzzer, and an LED when it is determined that the spot welding is abnormal;
Spot welding monitoring method comprising a.

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