KR101615903B1 - Automatic welding control device - Google Patents

Abstract

The present invention relates to an automatic welding control apparatus for detecting a welding current so as to accurately describe a geometric shape of a base material, thereby easily setting welding conditions and weaving conditions and improving welding accuracy, And generates a current value indicating the geometry of the base material by averaging the generated current data and the current data in the previous motion on the basis of the position to generate a current value based on the generated current value, An arc sensor for generating a width direction correction value and a depth direction correction value; A weaving module for controlling the weaving motion of the robot mechanism based on the width direction correction value and the depth direction correction value generated from the arc sensor; And a welding module for transmitting a current value to be output to the welding machine, receiving a current value from the welding machine, and transmitting the current value to the arc sensor, thereby implementing an automatic welding control device.

Description

[0001] Automatic welding control device [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic welding control apparatus and, more particularly, to an automatic welding control apparatus for acquiring a welding current so as to accurately describe a geometric shape of a base material and easily setting welding conditions and weaving conditions, .

Generally, various types of industrial robots are used in the industrial field, and welding robots are used for automatically welding various kinds of materials such as iron plates. In the welding using the welding robot, the base material to be welded is transported and fixed to the jig. When the welding start point and the welding end point on the welding line to be welded are inputted to the target base material, The torch is driven to perform welding.

Here, arc welding and the like are mainly used for welding the base material. Arc welding is a welding method in which a wire is supplied to a welding torch while a strong current is generated between the welding torch and the welding base material to melt and weld the wire and the base material instantaneously. When arc welding is performed, a predetermined welding condition is set in advance according to the type of the base material and the mutual contact shape of the welding part to be welded. These welding conditions include the welding current, the welding voltage, the distance between the welding torch and the base material, the feed rate of the wire, and the speed of the weaving motion by the welding torch.

Here, the weaving motion means that when the welding robot performs a welding operation, the robot moves in a zig-zag manner in the zig-zag direction, not in a straight line / curved line, but in a zig- .

When arc welding is performed using a welding robot, arc sensing is used for the weaving motion.

The arc sensing is to calculate the welding current value and the deflection value of the torch for the unit motion by acquiring the welding current during the weaving welding of the robot and comparing the welding current value and the deflection value of the torch with the reference current value and the reference deflection value, And adjusting the width direction to keep the welding current and track the weld line. Such arc sensing is widely tried in the field of welding automation because it can be implemented relatively simply by a combination of a device for measuring the welding current and software.

The weld seam tracking performance using the arc sensor is determined by how well the measured current describes the shape of the base material. However, the shape of the welding current obtained due to the fluid behavior of the molten pool, the non-linearity of the arc, the motion command, and the actual positional delay may not be able to represent the geometry of the base material. If the welding current is measured in an extremely skewed form, the computed torch deflection value is also calculated as an extremely skewed result, so that the correction value in the right and left direction may vibrate to a large extent and the system may become unstable. Therefore, in case of using arc sensing, the welding current and the weaving condition are finely adjusted so that the shape of the welding current can be well represented by the shape of the base material, or the tracking performance is lowered in order to improve the stability of the system. It can be difficult to apply.

In general arc sensing, the reference current value and the reference deflection value are measured at the beginning of the arc sensing. If the welding line and the torch have an offset, the reference current value and the reference deflection value are also designated as the offset values, There is a disadvantage in that offset is also applied to trace welding current and weld line.

In order to solve the above problems, a conventionally proposed technique is disclosed in the following Patent Document 1: Korean Patent Laid-Open Publication No. 10-2012-0035969 (Apr. 17, 2012) and Patent Document 2: 10-2012-0033524 (published on Apr. 9, 2012).

The prior art disclosed in Patent Document 1 sets a first reference point after starting the weaving operation and confirms whether the next weaving index is even when the weaving welding is started. If the weaving index is odd, weaving welding is continued until the weaving index becomes an even number, If it is an even number, it starts DAQ of welding current and if it reaches even index, it performs noise filter for welding current based on DAQ and obtains time delay. This Patent Document 1 can be implemented only by the robot itself without adding any additional measuring equipment, and it is possible to measure without considering the characteristics of the welding machine and the robot controller, and to cope with the noise generated at the welding Thereby minimizing the measurement error with respect to the amount of time delay.

The prior art disclosed in Patent Document 2 controls the welding apparatus and the height between the welding line and the torch by using an algorithm for measuring the welding current generated during arc welding and keeping the distance between the welding line and the torch end constant, The welding is performed in a state where the welding line and the torch are spaced apart from each other at a constant height without precise teaching.

Korean Published Patent Application No. 10-2012-0035969 (Published April 17, 2012) Korean Patent Publication No. 10-2012-0033524 (2012.04.09. Disclosed)

However, in order to effectively use the arc sensing value, the conventional art as described above requires a lot of efforts to precisely set an initial starting position, and has a disadvantage in that the welding line can not be traced in a section for measuring a reference value.

It is an object of the present invention to provide a welding method and a welding method for welding a workpiece by acquiring a welding current so as to accurately describe a geometric shape of a base material, And an automatic welding control device for improving the welding precision.

Another object of the present invention is to provide an automatic welding control device capable of accurately describing the geometry of the base material even when the fluid behavior of the molten pool, the non-linearity of the arc, the motion command, .

In order to achieve the above object, an automatic welding control apparatus according to the present invention generates current data by aligning current current values measured from a welder in the ice-making direction, and generates current data and current data An arc sensor for generating a current value representing a geometric shape of the base material by averaging based on the position and generating a width direction correction value and a depth direction correction value for weaving based on the generated current value; A weaving module for controlling the weaving motion of the robot mechanism based on the width direction correction value and the depth direction correction value generated from the arc sensor; And a welding module that transmits a current value to be output to the welding machine, receives a current value from the welding machine, and transmits the current value to the arc sensor.

The weaving module determines a weaving motion mode and transmits a signal of the index of the unit motion to the arc sensor while controlling the weaving motion by transmitting the position value at which the joint as the welding position should be positioned to the robot mechanism .

Wherein the arc sensor includes a welding data collecting module for sequentially storing the current values of the welding machine transmitted from the welding module during a unit motion.

The arc sensor further includes a noise filter for removing noise from a current value during a recent unit motion stored in the welding data collection module and generating current data when the arc sensor is in a new motion.

The arc sensor further includes an order conversion module for aligning the current data generated from the noise filter with respect to the weaving width direction according to the motion index.

The order conversion module generates the current data aligned in the weaving width direction by reversing the current data only when the motion index is an odd number.

Wherein the arc sensor further comprises a buffer for storing the aligned current data or the current data output from the noise filter as current data for the previous motion.

The arc sensor generates a current value indicating a geometric formation of the base material by sequentially averaging the current data arranged in the weir direction and the current data of the previous motion stored in the buffer through the noise filter or the order conversion module Based average filter that performs a position-based average filter.

Based on the current value output from the position-based averaging filter, the arc sensor calculates a deflection value calculating module for calculating a deflection degree of the torch with respect to the center; And a width direction correction value calculation module for generating a width direction correction value in inverse proportion to the deviation degree calculated by the deviation value calculation module using a preset widthwise proportional gain and transmitting the widthwise correction value to the weaving module.

The arc sensor may further include an average current value calculation module that averages the current values output from the position based average filter to generate an average current value.

In the above, the arc sensor is applied to the following equation (I_mean) using the preset depth direction proportional gain C_zw, the current value I_trg measured by the welding module, and the average current value I_mean generated by the average current value calculation module And a depth direction correction value calculation module for generating a depth direction correction value d_zw for the weaving motion.

<Formula>

According to the present invention, it is possible to easily set the welding condition and the weaving condition by acquiring the welding current so as to accurately describe the geometrical shape of the base material, and it is possible to improve the welding precision by accurately describing the geometric shape of the base material There are advantages to be able to.

Also, according to the present invention, even if the fluid behavior of the molten pool, the non-linearity of the arc, the motion command, and the delay of the actual position exist, the shape of the welding current can well describe the geometry of the base material, There are advantages to be able to.

1 is a block diagram of an automatic welding control apparatus according to a preferred embodiment of the present invention;
FIGS. 2A to 2C are explanatory diagrams for explaining a process of emphasizing the geometric characteristics of a base material in the present invention,
3 is a locus explanatory diagram of a robot weaving motion for a fillet joint in the present invention,
4 is a diagram of a typical welding current data form for weaving motion,
FIG. 5 is a diagram showing a welding current data form in which the geometrical characteristics of the base material according to the present invention are shown;
Fig. 6 is an illustration of welding current data at a welding distance of 170 mm,
Fig. 7 is a first example of the welding current data of the arc sensing in which the reference value measurement is not used,
Fig. 8 is a second example of welding current data of arc sensing in which reference value measurement is not used; Fig.

Hereinafter, an automatic welding control apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an automatic welding control apparatus according to a preferred embodiment of the present invention.

The automatic welding control apparatus according to the preferred embodiment of the present invention includes an arc sensor 100, a weaving module 200, a robot mechanism 300, a welder 400, and a welding module 500.

The robotic mechanism 300 operates the weaving motion of the welding torch according to the control of the weaving module 200. The welding machine 400 is operated based on the welding current generated by the welding module 500, Arc welding.

Here, the welding machine 400 and the robot mechanism 300 are components essential to a welding robot, which is generally known or referred to in the prior art, and are well known in the art, so a detailed description thereof will be omitted.

The welding module 500 transfers a current value I_trg to be output by the welding machine 400 to the welding machine 400 at each sampling time based on parameters required for preliminarily stored welding, And receives the current value I_act and transmits it to the arc sensor 100.

The arc sensor 100 generates current data I_dir (1: n) by aligning the present current value I_act measured from the welder 400 in the ice width direction and outputs the current data I_dir (1: n) representing the geometrical shape of the base material by averaging the current data I_dir (1: n) 'of the current data I_dir Value and a depth direction correction value and transmits it to the weaving module 200.

The arc sensor 100 includes a welding data collection module 102 for sequentially storing a current value I_act of the welding machine 400 transmitted from the welding module 500 during a unit motion; A noise filter for removing noise from a current value I_act (1: n) during a recent unit motion stored in the welding data collection module 102 and generating current data I_w (1: n) (103).

The arc sensor 100 further includes an order conversion module 105 for aligning the current data I_w (1: n) generated from the noise filter 103 with respect to the ice-making direction in accordance with the motion index (even and odd) ). &Lt; / RTI &gt; Here, the order conversion module 105 reverses the current data I_w (1: n) only when the motion index is an odd number and outputs the sorted current data I-dir (1: n) .

The arc sensor 100 outputs the current data I_dir (1: n) or the current data I_w (1: n) output from the noise filter 103 to the current A buffer 107 for storing data as data; The current data I-dir (1: n) 'of the previous motion stored in the buffer 107 and the current data arranged in the upper I-biquadratic direction outputted through the noise filter 103 or the order conversion module 105 Based average filter 106 that generates a current value I_go (1: n) representing the geometric shape of the base material by averaging in order.

Preferably, the arc sensor 100 calculates a deflection value calculation (e.g., a deflection value calculation) that calculates the degree of deflection (W) of the welding torch against the center, based on the current value I_go Module 109; Directional correction value that is inversely proportional to the deflection degree W calculated by the deflection value calculation module 109 using the preset widthwise proportional gain C_yw and transmits the widthwise correction value to the weaving module 200 0.0 &gt; 110 &lt; / RTI &gt;

More preferably, the arc sensor 100 calculates an average current value I_mean by averaging the current values I_go (1: n) output from the position-based averaging filter 106 ); And calculates the average current value I_mean generated by the average current value calculation module 108 and the current current value I_trg measured by the welding module 500 in accordance with a predetermined depth direction proportional gain C_zw, And a depth direction correction value calculation module for generating a depth direction correction value d_zw.

The weaving module 200 controls the weaving motion of the robot apparatus based on the width direction correction value and the depth direction correction value generated from the arc sensor 100. The weaving module 200 determines a weaving motion mode (a motion mode, a new motion) while controlling the weaving motion by transmitting a position value to which the joint, which is a welding position, should be positioned, to the robot mechanism 300, (Even and odd) of the arc sensor 100 to the arc sensor 100.

1, reference numerals 101 and 104 denote switches.

The operation of the automatic welding control apparatus according to the preferred embodiment of the present invention will now be described in detail.

Basically, the welding robot includes a robot mechanism 300 and a welding machine 400, and the weaving module 200 and the welding module 500 perform control on the robot mechanism 300 and the welding machine 400. At this time, parameters required for weaving and parameters necessary for welding by the robot program are transmitted to the weaving module 200 and the welding module 500, respectively.

The weaving module 200 transmits a value th (1: 6) to which the joints 1 to 6 should be positioned to the robot mechanism 300 for each sampling time, and the welding module 500 transmits the value th (1: (I_trg) to the welder (400) and receives the current value (I_act) from the welder (400).

In addition, the weaving module 200 controls the weaving motion so that the weaving motion mode indicating whether the weaving motion (in motion) or the new weaving motion should be planned (new motion), the motion index indicating whether the index of the unit motion is an even or odd number And transmits the signal to the arc sensor 100.

If the weaving motion mode generated by the weaving module 200 is "during motion", the arc sensor 100 sets the current value I_act received from the welding module 500 as a unit The welding current (I_act (1: n)) during motion is stored in the internal buffer in order.

Next, when the weaving motion mode indicates "new motion ", the arc sensor 100 generates a width direction correction value and a depth direction correction value for adjusting the weaving motion of the welding torch and transmits it to the weaving module 200, Here, if the weaving motion mode is "in motion ", the weaving module 200 controls the weaving motion of the robot mechanism 300 using the previously obtained width direction correction value and depth direction correction value as they are.

When the weaving motion mode is the "new motion ", the noise filter 103 outputs current data (I_act (1: n)) obtained by removing the fundamental noise from the current data I_act I_w (1: n)).

The arc sensor 100 determines whether the motion index outputted from the weaving module 200 is an odd number or an even number and outputs current data I_w (1: n) output from the noise filter 103 If the motion index is an odd number, the sequence conversion module 105 reverses the current data I_w (1: n) and generates current data I_dir (1: n) aligned in the weaving width direction Where the weaving width direction is defined as the direction of motion when the motion index is an even number.

Here, the current measurement values for the unit motion are complexly intertwined with the geometry of the base material, various phenomena related to the arc characteristics, the behavior of the molten pool, and the motion generation. It is actually difficult to separate only the geometric characteristics of the parent material from the current values measured in the unit motion. In addition, even if the arc characteristics and the characteristics of the behavior of the melt pool are defined in various ways, the value may no longer be used in another welding environment. However, since these factors have a similar tendency for the welding, if the welding current value of the previous unit motion and the welding current value of the corresponding motion are averaged with respect to the position, the phenomena other than the geometrical influence are canceled to a great extent and the influence of the geometric shape Can be the main data. Since the processed welding current data shows the characteristics of the geometric shape of the base material well, it is possible to use less effort to adjust the welding condition and weaving condition in using arc sensing, and the system with high stability and high tracking performance This is very useful for implementing welding automation using arc sensing.

FIGS. 2A to 2C are conceptual diagrams showing that various phenomena other than the geometric characteristics of the base material are mixed with the welding current values measured in the unit motion, and the geometric characteristics of the base material are left by canceling them. 2A and 2B can be regarded as current data measured while moving in the width direction with respect to the center of the base material, but the data is not located at the center and is somewhat delayed (the horizontal axis indicates the width direction position and the vertical axis indicates the current Lt; / RTI &gt; Taking the average value of the data measured over these two times as the position reference, a current value as shown in FIG. 2C can be obtained. The data is centered and the concave is emphasized. That is, the geometric characteristics of the base material are well visible.

To this end, in the present invention, current data I_dir (1: n) aligned in the weaving width direction is extracted using the position-based averaging filter 106 in order to emphasize the geometrical characteristics of the base material for the motion, And the current data I_dir (1: n) 'in the previous motion stored in the buffer 107 are averaged according to the order (location basis) as shown in the following equation (1) (I_go (1: n)). Here, the current data I_dir (1: n) aligned with the weaving direction is stored in the buffer 107 for use in the next motion.

Another aspect of the present invention is to provide a welding control apparatus for omitting a process of measuring a reference current value and a reference deflection value. Even though the welding torch has the welding line and offset at the beginning of the arc sensing, the welding torch is converged on the welding line through the arc sensing using the arc sensor proposed in the present invention, so that the initial starting position is not precisely set, It is advantageous to extend the duration of the operation.

For example, the deflection value calculation module 109 uses the current value I_go (1: n) to generate the degree of deviation (W) of the welding torch with respect to the center. The method of obtaining the degree of deflection of the welding torch with respect to the center is as shown in the following equation (2), and it is preferable to apply the method used in the conventional arc sensor as it is.

Next, the width direction correction value calculation module 110 generates the width direction correction value d_yw in inverse proportion to the deflection degree W using the preset widthwise proportional gain C_yw, 200). Here, the reference deflection value is not used for calculating the widthwise correction value, and the widthwise proportional gain (C_yw) is defined by the user. Although the basic control method is used here, in some cases, an integral gain or differential gain can be used.

Meanwhile, the average current value calculation module 108 generates the average current value I_mean of the corresponding motion using the current value I_go (1: n) output from the position-based averaging filter 106. The depth direction correction value calculation module 111 calculates the depth direction proportional gain C_zw and the average welding current I_mean of the motion and the target current value I_trg in the welding module 500 according to the following mathematical formula (3)] to generate a correction value d_zw in the weaving depth direction, and transmits the correction value d_zw to the weaving module 200. Where the depth direction proportional gain (C_zw) is defined by the user. Although the basic control method is used here, in some cases, an integral gain or differential gain can be used.

The weaving module 200 applies the width direction correction value and the depth direction correction value to generate the next unit motion, and repeats this process to track the welding line.

On the other hand, the present inventor has experimented to prove the effect of the proposed automatic welding control apparatus.

Fig. 3 shows the locus of the vertical fillet joint and the weaving motion under test. The starting position of the welding is -2.5 mm offset in the weaving width direction from the center of the fillet, and the order of the unit motion is specified from 1. In the present invention, an even number of motion directions is defined as a weaving width direction, but an odd number is defined as a weaving width direction in the following test data. The implementation of this was as described in the present invention, but due to the nature of the program plotting the data, the following was reversed.

Fig. 4 shows general welding current data for weaving motion, and Fig. 5 shows welding current data showing the geometrical characteristics of the base material to which the proposal of the present invention is applied.

In FIG. 4, a method of measuring the reference deflection value and the reference current value is applied, and the measurement position is a welding distance of about 15 mm. The horizontal axis is the sampling order arranged in the weaving width direction and the vertical axis is the ADC value of the current data. The legend represents the index of the unit motion. In Fig. 4, the behavior of the molten pool, the arc characteristic, and the motion characteristic are mixed in addition to the shape characteristic of the base material. When this data is used to calculate the deflection value of the corresponding motion, it becomes unstable. 5 shows the data processed by the method of the present invention. The geometric shape of the expected joint is reflected, and a concave shape appears in the left part of the center (about 50 on the horizontal axis).

6 shows the welding current data measured at a welding distance of about 170 mm in the welding. 5, the geometry of the joint is reflected, and a concave shape appears in the left part (about 50 on the horizontal axis) at the center. However, since the method of measuring the reference deflection value and the reference current value and using the method to obtain the correction value is used, it can be seen that the welding started at an offset of about 2.5 mm is maintained even after 170 mm.

FIGS. 7 and 8 are graphs showing a relationship between a welding current value and a welding current value for a weaving motion when a correction value is calculated using the data processing method proposed in the present invention, and an arc sensing method in which a reference deflection value and a reference welding current are not measured is used . The initial offset was -2.5 mm in the weaving width direction as in the above test. (Fig. 7) and 170 mm (Fig. 8), respectively. In both cases, it can be seen that the geometric characteristics of the base material are well represented. However, since the arc sensing method which does not measure the reference deflection value and the reference welding current is used, the graph is deflected from the center to the left in the vicinity of 15 mm, but converges to the center in the case of 170 mm.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

The present invention is effectively applied to welding robot technology capable of precisely describing the geometry of the base material and precisely controlling the weaving motion without measuring the reference deflection value and the reference current value.

100: arc sensor
102: welding data acquisition module
103: Noise filter
105: order conversion module
106: Location-based average filter
108: Average current value calculation module
109: Deflection value calculation module
110: Width direction correction value calculation module
111: Depth direction correction value calculation module

Claims (10)

Generates the current data by aligning the current value measured from the welder in the ice width direction, generates the current data representing the geometry of the base material by averaging the generated current data and the current data in the previous motion based on the position, An arc sensor for generating a width direction correction value and a depth direction correction value for weaving based on a current value;
A weaving module for controlling the weaving motion of the robot mechanism based on the width direction correction value and the depth direction correction value generated from the arc sensor;
And a welding module for transmitting a current value to be output to the welding machine, receiving a current value from the welding machine, and transmitting the current value to the arc sensor,
Wherein the arc sensor comprises: a welding data collection module for storing current current values of a welding machine delivered from the welding module in order during a unit motion; A noise filter for removing noise from the current value during the recent unit motion stored in the welding data collection module and generating current data; And an order conversion module for aligning the current data generated from the noise filter with respect to the weaving width direction according to the motion index.
[2] The method of claim 1, wherein the weaving module determines a weaving motion mode by transmitting a position value to which the joint, which is a welding position, should be positioned, to the robot mechanism to control the weaving motion, To the automatic welding control apparatus.
delete delete The automatic welding control apparatus as claimed in claim 1, wherein the order conversion module generates current data sorted in the upwind direction by reversing the current data only when the motion index is odd.
The automatic welding control apparatus according to claim 1, wherein the arc sensor further comprises a buffer for storing the aligned current data or the current data output from the noise filter as current data for previous motion.
The arc sensor according to claim 6, wherein the arc sensor sequentially averages the current data of the previous motion stored in the buffer and the current data aligned in the weaving width direction outputted through the noise filter or the order transformation module to indicate geometric formation of the base material Further comprising a position based average filter for generating a current value.
8. The apparatus of claim 7, wherein the arc sensor comprises: a deflection value calculation module that calculates an extent to which the welding torch is deflected relative to a center based on a current value output from the position-based averaging filter; Further comprising a width direction correction value calculation module for generating a widthwise correction value in inverse proportion to the deviation degree calculated by the deviation value calculation module using a preset widthwise proportional gain and transmitting the widthwise correction value to the weaving module. Control device.
The automatic welding control apparatus according to claim 7, wherein the arc sensor further comprises an average current value calculation module for averaging the current values output from the position-based average filter to generate an average current value.
The arc sensor according to claim 9, wherein the arc sensor has a predetermined depth direction proportional gain (C_zw), a current value (I_trg) measured by the welding module, and an average current value (I_mean) Further comprising: a depth direction correction value calculation module for applying the depth direction correction value (d_zw) for the weaving motion to the depth direction correction value (d_zw).
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