KR20050047232A - Appratus of inspecting welding quality and method thereof - Google Patents

Abstract

The present invention relates to a welding quality inspection apparatus and method that can detect the physical quantity that influences the welding quality by using a sensor and to make a data to evaluate the welding quality in an online state, the present invention, for more accurate welding quality management The welding current and the welding voltage are detected on the secondary side of the transformer, the pressing force is detected using a sensor for detecting the pressure of the pneumatic cylinder, and the amplified physical quantity is amplified and processed and dataized. In addition, in the case of resistance welding machine, several welding machines divide various tasks into individual processes and combine them to implement the whole product. Therefore, for quality control of welding, the output data of the interface parts of individual welding machines are collected and statistical techniques are used. Information management is performed using.

Description

Apparatus of inspecting welding quality and method

The present invention relates to a welding quality inspection apparatus, and in particular, when the production of the product by the welding method welding quality inspection apparatus and method that can evaluate the quality of the product during the production process by detecting and inspecting the factors affecting the quality of the welding It is about.

1 is a view showing the configuration of a conventional separate resistance welding machine.

As shown therein, a transformer (transformer) 13 which supplies a suitable voltage to the S-type gun 11 and the J-type gun 12, the S-type gun 11 and the J-type gun 12, which are welding guns, are provided. And a power switch 14, a beam 15, a rail 16, a trolley 17, a hanger 18, a spring balancer 19, a secondary cable 20 which is a power supply cable.

Figure 2 is a view showing the configuration of a conventional static resistance welder in the form of a separate resistance welder combined as one structure as described above.

As shown therein, the power switch 21, the timer contactor 22 as a power control device, a transformer 23 for supplying a suitable voltage, a pneumatic cylinder 24, a solenoid valve 25, a push button 26 And an electrode 27, a holder 28, and a foot switch 29.

In the figure, reference numeral 30 denotes a coolant inlet, and 31 denotes a coolant outlet.

3 is a schematic configuration diagram of a conventional resistance welding robot system in which only a welding gun and a transformer are integrated and a timer contact is separated.

This is a schematic diagram of a general resistance welding robot system using a resistance welding machine mounted on a robot.

As shown therein, the controller box 41, the timer contactor 42 of the resistance welder, the relay box 1 43, the support 44, the transformer 45, the resistance welding gun 46, the robot body 47 ), Tip dress 48, relay box 2 (49) and the like.

In the general resistance welding robot system configured as described above, the resistance welding gun and the transformer are integrally formed, and the timer contactor is separated.

All three systems described above represent a resistance welding system using resistance welding.

In general, when the product is produced by the resistance welding method as used in the automotive industry, there is a fracture test method for measuring the quality of non-destructive test and tensile strength. This method is to assess the quality of a product after its production. Therefore, this method has a disadvantage in that the quality cannot be evaluated during the production process, as in the case of mass production of products.

Therefore, in recent years, the method of detecting the quality of resistance welding in the production process of a product is proposed.

Here, three main factors that determine the quality of resistance welding are welding current, energization time, and pressing force. When this physical quantity is detected and compared with a preset reference value, it is possible to determine the conditions of the process in which resistance welding is performed. Techniques capable of detecting these physical quantities are known techniques.

Until now, the method of detecting the welding current and the energization time among these physical quantities has been used on the primary side of the transformer or on the output side of the timer contact. This is because it is economically advantageous to incorporate a function for detecting a welding current from the output of the timer contact, which is a power control device for welding, and the energization time from the timer contact.

However, when the welding current is detected by this method, the current leakage in the path and the conversion loss on the secondary side of the transformer cause a difference from the amount of current when the welding is performed. In order to compensate for such a difference, a system having a function of measuring or calculating the amount of difference and compensating for the difference has been proposed.However, this also sets a predetermined amount of information to be compensated. There is a disadvantage that it is not practically possible to properly compensate for each reflection.

As is well known, the welding current, energization time, and pressing force information detected at the primary side of the transformer or at the output of the timer contactor are used as a criterion for judging whether the quality is good or bad by comparing with a preset reference value. In this case, it is possible to determine the welding quality online on the spot. However, since the welding quality is compared with a preset reference value, if the reference value is strictly applied, there is a high possibility that a lot of defects will occur. On the contrary, if the reference value is applied low, a good result may later work poorly.

Accordingly, an object of the present invention is to provide an apparatus and method for evaluating welding quality in an on-line state by detecting a physical quantity that influences welding quality using a sensor and converting the data into data.

Welding quality inspection apparatus of the present invention for achieving this object,

A welding quality inspection apparatus for a resistance welding robot system having a transformer and a pneumatic cylinder, comprising: a current sensor and a voltage sensor provided at an output side of the transformer to detect a welding current and a welding voltage; A pressure sensor provided at an output side of the pneumatic cylinder and detecting a pressing force; Amplify each signal output from the current sensor, voltage sensor and pressure sensor, convert it into digital data, convert it into a predetermined form, and store it in a memory, and store the stored data in the form of serial communication. An interface unit for converting the output unit; A communication controller which performs timing and control of data output from the interface unit; It characterized in that it comprises a SPC (Statistical Process Control) server for determining the welding quality by statistically analyzing and inspecting the information output from the communication control during the production process.

In addition, the welding quality inspection method of the present invention,

In the welding quality inspection method of a resistance welding robot system having a transformer and a pneumatic cylinder, the welding current and the welding voltage are detected on the secondary side of the transformer, the pressing force of the pneumatic cylinder is detected, and the welding current and the welding voltage. Amplifying the detection signals of the pressing force, converting the amplified detection signals into digital data, storing them in a memory, performing timing and control of the data, and statistically analyzing and inspecting the output information during the production process to weld quality. It characterized in that it comprises a step comprising determining.

Hereinafter, described in detail with reference to the accompanying drawings, preferred embodiments of the present invention according to the technical spirit as described above.

In the present invention, the current sensor, the voltage sensor, and the pressure sensor use those of a generally known technique. The information received from them is converted into information that can be transmitted to the communication control device. In this case, the transducers are used one by one to welder quality information. Since many production processes use several to tens or hundreds of welding machines, communication control devices are implemented in a serial connection structure so that welding quality information from them can be simultaneously analyzed and inspected.

4 is a block diagram showing the configuration of a welding quality inspection device according to the present invention.

As shown therein, a current sensor 101 and a voltage sensor 102 provided at the output side of the transformer to detect the welding current and the welding voltage, and a pressure sensor 103 provided at the output side of the pneumatic cylinder to detect the pressing force; After amplifying the respective signals output from the current sensor 101, the voltage sensor 102, and the pressure sensor 103, performing signal processing, converting them into digital data, converting them into a predetermined form, and converting them into a memory. An interface unit 110 for storing and converting the stored data into a form capable of serial communication, and a communication controller 120 for timing and controlling data output from the interface unit 110; It consists of a statistical process control (SPC) server 130 to statistically analyze the information output from the communication control unit 120 and performs an inspection function.

Figure 5 is a block diagram showing an embodiment configuration of the interface unit 110 and the communication control unit 120 of the welding quality inspection apparatus according to the present invention.

As shown therein, the interface unit 110 amplifies each signal output from the current sensor 101, the voltage sensor 102, and the pressure sensor 103, performs signal processing, and then outputs an analog signal. In the sensor circuit module 111, the analog / digital conversion module 112 for converting the analog signal output from the sensor circuit module 111 to the corresponding digital data, and in the analog / digital conversion module 112 A data storage module 113 for converting the digital data output to a predetermined form and storing it in a memory, and a communication for converting the data stored in the data storage module 113 into a form capable of serial communication and outputting the converted data. Module 114.

In addition, the communication control unit 120 is connected to the communication module 114 in the interface unit 110, the communication connection module 121 for receiving data interface, and the data is connected and transmitted to the communication connection module 121 It consists of a communication control module 122 to perform the timing and control of.

Looking at the action of the welding quality inspection apparatus according to the present invention configured in this way in more detail as follows.

First, the current sensor 101 and the voltage sensor 102 are connected to the output terminal of the secondary side of the welding machine transformer (see FIG. 3), and detect the current and voltage outputted to the secondary output terminal to the interface unit 110. To pass.

In addition, the pressure sensor 103 is installed in a suitable place that can detect the air pressure in order to detect the pressing force of the welding gun (see Fig. 3), by using a pressure gauge to detect the pressing force of the welding gun by the interface unit 110 To pass). The pressure sensor 103 is preferably provided at a suitable place on the input side of the pneumatic cylinder (see Fig. 3), and the pressure is preferably measured.

Since the detected current, voltage, and pressure detection values are minute signals, the sensor circuit module 111 in the interface unit 110 amplifies the minute current, voltage, and pressure detection values to a predetermined level to enable signal processing at a later stage. After performing the process of filtering and so on, it is converted into a signal form that can be processed in the later stage and output as an analog signal.

The analog / digital conversion module 112 converts the analog signal output from the sensor circuit module 111 into a digital signal through a sampling process and transfers the analog signal to the data storage module 113 as welding quality determination data.

The data storage module 113 converts the delivered welding quality determination data into a predetermined form and stores the data in the internal memory. If necessary, the data storage module 113 extracts the welding quality determination data stored in the memory and the server 130. And converts the data into a form that can be transmitted to the communication module 114.

The communication module 114 converts the transmitted welding quality determination data into a form capable of serial communication (RS422) and transmits the data to the communication controller 120.

Herein, the present invention is designed to have a daisy chain structure as shown in FIG. 4 so that several interface units can be simultaneously processed by one SPC server. And it is desirable to install the interface as close as possible to each sensor module.

A communication line should be created so that the output of several interface units can be simultaneously processed by one SPC server.

Therefore, the output of the communication module 114 in the interface unit 110 is transmitted to the communication control module 122 via a connector box called a communication connection module 121 in the communication control unit 120. The communication control module 122 performs the timing and appropriate control of the welding quality determination data transmitted according to a predetermined rule and transmits it to the server 130. In this case, the communication connection module 121 is installed together with the interface unit 110, and the communication control module 122 is installed at a suitable place to easily connect with several interface units.

The server 130 statistically analyzes the information obtained from each sensor module transmitted and performs a test. Here, the SPC performs process control by a known statistical technique, and a detailed description thereof will be omitted. In addition, the SPC server may be placed in any place, such as a production process or an office, depending on the user's environment and situation.

In the preferred embodiment of the present invention described above, only the welding voltage and the welding current and the pressure is detected as a welding condition, and the welding quality is inspected using the same. However, the present invention is not limited thereto. Pressure may optionally be used to check weld quality.

According to the present invention as described above, by detecting the welding voltage and current on the secondary side of the welding transformer, by detecting the pressing force of the pneumatic cylinder, it is possible to analyze and determine the information of the welding conditions during the production process It works.

In addition, it is possible not only to determine the welding quality on the spot during the production process, but also to statistically analyze and inspect the welding quality information.

In addition, there is an advantage that the welding quality inspection can be performed in real time, it is also possible to statistically analyze the variation of the welding conditions.

1 is a view showing the configuration of a conventional separate resistance welder,

2 is a view showing the configuration of a conventional static resistance welding machine,

3 is a view showing the configuration of a conventional resistance welding robot system,

4 is a block diagram showing the configuration of a welding quality inspection apparatus according to the present invention,

FIG. 5 is a block diagram illustrating a configuration of each part of FIG. 4.

<Explanation of symbols for the main parts of the drawings>

101 ..... Current sensor

102 ..... Voltage sensor

103 ..... Pressure sensor

110 ..... Interface

111 ..... Sensor circuit module

112 ..... analog / digital conversion module

113 ..... Data storage module

114 ..... Communication Module

120 ..... Communication Control Unit

130 ..... Server

Claims (5)

In the welding quality inspection device of a resistance welding system having a transformer and a pneumatic cylinder, A current sensor and a voltage sensor provided at an output side of the transformer to detect a welding current and a welding voltage; A pressure sensor provided at an output side of the pneumatic cylinder and detecting a pressing force; Amplify each signal output from the current sensor, voltage sensor and pressure sensor, convert it into digital data, convert it into a predetermined form, and store it in a memory, and store the stored data in the form of serial communication. An interface unit for converting the output unit; A communication controller which performs timing and control of data output from the interface unit; And a SPC (Statistical Process Control) server for determining the welding quality by statistically analyzing and inspecting the information output from the communication control unit during the production process. The method of claim 1, wherein the interface unit, The welding quality inspection apparatus, characterized in that each of the signals output from the current sensor, the voltage sensor and the pressure sensor to take selectively or all taken as the welding condition information for welding quality inspection. The method of claim 1, wherein the interface unit, A sensor circuit module for amplifying each signal output from the current sensor, the voltage sensor, and the pressure sensor, processing the signal, and outputting the signal as an analog signal; An analog / digital conversion module for converting an analog signal output from the sensor circuit module into digital data corresponding thereto; A data storage module for converting the digital data output from the analog / digital conversion module into a predetermined form and storing the same in a memory; Welding quality inspection device comprising a communication module for converting and outputting the data stored in the data storage module in a form capable of serial communication. The method of claim 1, The communication control unit, A communication connection module for connecting with a communication module in the interface unit to receive data; And a communication control module configured to perform timing and control of data transmitted in connection with the communication connection module.        In the welding quality inspection method of a resistance welding robot system having a transformer and a pneumatic cylinder, Welding current and welding voltage are detected on the secondary side of the transformer, Detecting the pressing force of the pneumatic cylinder, Amplifying the detection signals of the welding current, welding voltage, and pressing force; Converting the amplified detection signal into digital data and storing the same in a memory; And determining the welding quality by statistically analyzing and inspecting the information output by performing timing and control of the data during a production process.