JPH09206943A - Profile control method for automatic weld profiling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stable high-precision profile control, in a weld profile control method, even in a weld state of short circuiting transfer in which short- circuit/arc is repeated. SOLUTION: In this control method for a automatic weld profiling device in which an arc welding method is used in tracking a weld line with an electrode oscillated or rotated, a pulse peak starting signal P1 is received from a pulse welding machine 2 at the rising time of a peak current, a pulse peak ending signal P2 is received at the falling time, setting a pulse section between the starting P1 signal and the ending P2 signal, detecting a current value within the pulse section at a preset period, setting a detected current value from the current selected at a preset timing among the detected current values thus obtained, thereby making it a positional information in the groove width direction and the wire projecting direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying control method in an automatic welding copying control apparatus for weaving welding using a pulse welding machine or high speed rotary welding.

[0002]

2. Description of the Related Art In conventional weaving welding profile control,
The welding current value and the welding voltage value are synchronized with the weaving operation through a low-pass filter having about twice the weaving frequency, and the welding current value and the welding voltage value are measured at a preset cycle. The measured values are compared on both sides and in the center of each weaving section. That is, at both ends, the detected value in the weaving left section and the detected value in the weaving right section are compared to determine the positional deviation in the groove width direction. Further, the average value of the detected values of the central section of weaving or all the sections of weaving is calculated and compared with a preset value to judge the wire protrusion longitudinal deviation. When each direction deviation is determined, each correction signal is output to the robot controller side.

FIG. 6 is a block diagram showing a structure relating to a conventional welding line tracing control method as described in Japanese Patent Publication No. 53-11502. 1 is a welding torch, 12 is a current detector, and 13 is a current detector. Voltage detector, 2 is a welding machine, 3
Is a robot controller. In the control device 3, the current detector 12 and the voltage detector 13 cause the current detection signal and the voltage detection signal to pass through the low-pass filter-equipped A / D converter 31 through which the frequency component of 1 to 2 times the weaving operation frequency passes. Through 32, an analog signal is converted into a digital signal. In order to command the detection section for detecting the gap width direction deviation and the wire protrusion length direction deviation, the weaving calculator outputs the position information regarding the weaving operation, that is, the weaving signal output at the timing at both ends and the center of the weaving operation. The phase correction value stored in the phase correction value storage section 40 is output from the phase correction value storage section 40 at the same time as being output from the detection section commander 39 to the weaving operation and at the same time correcting the phase shift of the current value signal and the voltage value signal. The time is output to the detection section commander 38. Based on the weaving signal and the phase delay signal, the detection interval command unit 38
Outputs an integration command to the integrators 33 and 34, and the obtained detection current value is calculated by the groove width direction calculator 36 and the wire protrusion length direction calculator 37 in each detection section, and the groove width direction is calculated. The correction signal and the wire protrusion length direction correction signal are output to the robot operation control system 41. A welding contour control method for a pulse welder is disclosed in Japanese Patent Laid-Open No. 7-204853. First, the welding current value is detected, and when it is larger than the preset current value, it is determined that it is the peak pulse portion of the welding current.From the welding current value of only the peak pulse portion and the arc voltage at that time, the welding torch is determined. It is possible to detect the relative position to the object to be welded.

[0004]

However, the Japanese Patent Publication Sho 53
In the prior art such as Japanese Laid-Open Patent Publication No. 11502, the welding current value and the welding voltage value that have passed through the low-pass filter of about twice the weaving frequency are detected at the timing of the weaving signal on the robot control side, that is, at both ends and the center of the weaving signal. , The peak current value (or voltage value) and the base current value (or voltage value) are mixed as the detected value, so it is mainly used in addition to the current value that accompanies the wire protrusion length change as the positional deviation information. Since the current value due to a short circuit that occurs in the base current portion is included, it is not possible to perform accurate welding profile control.

Further, in the control method disclosed in Japanese Patent Laid-Open No. 7-204853, it is determined that the detected current value is the peak pulse portion of the welding current because the detected current value is larger than the preset current value. Under the following conditions, the peak pulse section may be mistakenly recognized. 1) In the base section, since the current value (70A to 120A) is such that the arc does not extinguish, short circuit occurrence concentrates in this section, and a short circuit open current pattern for opening the short circuit is inserted. As a result, when a large short circuit occurs, the current value becomes almost the same as the peak current value. Therefore, the short-circuit open current pattern section is erroneously determined as the peak pulse. 2) When the secondary power cable of the welding machine is long due to the layout of the welding system (for example, ± total cable length 40
m), the inductance of the power cable increases,
It does not rise to the command peak pulse current value. Therefore, the peak pulse section cannot be determined. Furthermore, when the current value in one peak pulse section is detected, the timing of the detachment of the molten droplet at the tip of the wire differs depending on the viscosity of the welding wire and the peak current pattern. A minute short circuit occurs and the short circuit current value is included in addition to the arc current value. The present invention
The present invention has been made in order to solve the above problems, and an object thereof is to provide stable and accurate welding profile control even in a welding state in which a short circuit / arc is repeatedly repeated.

[0006]

A welding contour control method of the present invention for achieving the above object is an automatic welding contour control apparatus which follows a welding line while swinging or rotating an electrode using an arc welding method. In the control method, the pulse peak start signal P1 is received from the pulse welding machine at the rising of the peak current, the pulse peak end signal P2 is received at the falling timing, and the pulse peak start signal P1 signal to the pulse peak end signal P2 signal are received. As a pulse section, the current value in the pulse section is detected at a preset cycle, and the current value selected at a preset timing among the obtained detected current values is set as the detected current value, It is characterized in that it is position information in the pre-radiation direction and the wire protruding direction. The present invention, when welding using a pulse welding power source, receives a welding current value (or voltage value) from the welding power source, and receives a peak timing signal from the welding power source.
Detects the current value in the first half, middle part, and second half of the peak part, and based on the current value obtained here, detects the integrated value between the minimum values in both ends and the center part of the weaving section. Since the current value is positional information in the groove width direction and the wire protrusion length direction, it is possible to stably perform the welding copying operation even if a short circuit occurs.

[0007]

1 is a block diagram showing the configuration of an embodiment of the present invention, in which 1 is a welding torch, 12 is a current detector, 13 is a voltage detector, and 2 is a pulse welder. Three
Is a robot controller. In the controller 3, the current detector 12 and the voltage detector 13 convert the current detection signal and the voltage detection signal into analog signals from A / D converters 31 and 32 into digital signals. This converted signal is
The detection command device 35 receives the pulse generation signal sent from the pulse welding machine and the peak pulse timing command signal from the peak pulse timing command device 42 at the time when the pulse generation signal is received and at the peak pulse timing command. In order to detect the signal only during the commanded time, the detection request device 35 outputs the integration request signal to the integrators 33 and 34 for integrating the current value signal / voltage value signal, and the signals are integrated. The current value signal / voltage value signal integrated here is
It is a detection signal selected in each peak pulse section and at a preset timing. This detection signal is used as a groove width direction calculator 36 and a wire protrusion length direction calculator 37.
Sent to Next, in order to command the detection section for detecting the groove direction deviation and the wire protrusion long direction deviation, first, the position information regarding the weaving operation, that is, the weaving signal output at the timing at both ends of the weaving and the central portion is weaved. Detecting section commander 3 from calculator 39
8 and at the same time, the phase delay time is detected from the phase correction value storage unit 40 in which the weaving operation and the phase correction value for correcting the phase shift of the current value signal and the voltage value signal are stored in advance. 38 is output. Based on the weaving signal and the phase delay signal, the detection section commander 38 detects the detected current value obtained in the peak pulse current value section, that is, the detection signal selected at the preset timing in the peak pulse section. In the section, the calculation is performed by the groove width direction calculator 35 and the wire protrusion length direction calculator 36, and the groove width direction correction signal and the wire protrusion length direction correction signal are output to the robot operation control system 40.

The block diagram showing the configuration of the embodiment of the present invention has been described above. Next, a control method particularly different from the conventional control method of the present invention will be described. That is, the present invention pays attention only to the peak current value of the peak section where the arc is generated, not the base current value section where the occurrence of the short circuit is concentrated, in the welding current value of the pulse welding machine. The welding current value is acquired at the timing when the tip of the wire melts and the molten droplet separates from the tip of the welding wire, and is used as positional deviation information of the welding line. Therefore, according to the present invention, the timing of the peak pulse is first received by the robot controller as a discrete signal from the circuit that outputs the welding current command from the welding machine side, so that the peak pulse is read incorrectly (missed) due to various disturbances. ) Is prevented. Furthermore, as a result of analyzing the welding phenomenon of one droplet (drop) per pulse unique to the welding method in the pulse welder, the viscosity of the welding wire, the component of the shield gas, the current pulse pattern (peak current, peak time, base) It has been confirmed by experiments that the timing at which droplets separate from the tip of the welding wire varies depending on factors such as current and base time), and it is possible to reliably detect the current value at the timing at which droplets separate from the molten portion of the welding wire. In the state where no short circuit (including a minute short circuit) has occurred, the arc current value with the highest probability can be extracted as the welding line position deviation information. First, some of the experimental results will be described below.

2 and 3 are diagrams modeling the welding current waveform and the time course of the molten state at the tip of the welding wire. FIG. 2 shows the case of the welding wire a and FIG. 3 shows the case of the welding wire b, in which the components of silicon, manganese and sulfur are different, the viscosity of the welding wire is different, and
Has a relatively low viscosity as compared with the welding wire b and is free flowing. Shielding gas _{(Ar80% + CO 2 20%} ), welding speed, welding current value, a welding voltage value, a pulse waveform and the like are the same conditions, it is only the results of experiments conducted while varying the welding wire. As can be seen from this figure, the timing at which the droplets separate from the tip of the welding wire is different. That is, in FIG. 2, the time from the start of droplet formation to the droplet detachment is 2.2 msec, and the droplet detachment is one detachment within one pulse period. Further, in FIG. 3, the time from the start of droplet formation to the droplet detachment is 2.86 msec, and the droplet detachment is not completed by one detachment but is about two droplet detachments. This is because the conditions are almost the same except for the welding wire, so that the droplets melted with the same heat input amount can be smoothly separated in the welding wire a having low viscosity, but the welding wire b has high viscosity. It can be seen that due to the surface tension of the droplets and the like, the welded wire fusion zone and the droplets do not easily break, and the detachment is not performed smoothly.

From these results, it was explained that the relationship between the timing of droplet detachment and the period of the pulse current differs depending on the welding wire or the like. Therefore, the peak pulse timing command value is stored in advance in the peak pulse timing command storage unit 43 for each of various welding wires, various pulse welding machines, various shield gases, etc. By outputting to the timing command device 42, it is possible to reliably acquire the welding current value and the welding voltage value in the peak pulse section and in the state where the droplet has separated. In addition, based on the current value and voltage value acquired here, the current value and voltage value are calculated in each detection section of the groove radial direction deviation and wire protrusion longitudinal direction deviation, and the groove radial direction correction signal and wire The protruding longitudinal correction signal can be obtained. Further, as described above, when the droplet detachment timing is not uniquely determined under various conditions, that is, when the droplet detachment timing fluctuates, first aim at the actual welding line without any positional deviation. Stores the detected current value during the entire peak pulse section during welding. Next, welding is performed so as to intentionally cause a positional deviation from the actual welding line, and similarly the detected current value in the entire peak pulse section is stored, and the current between the stored detected current values with and without the positional deviation is stored. The detection timing in the peak pulse having the most different value distribution is obtained, stored in the peak pulse timing command value storage unit 43, and the above processing is performed.

Further, when the droplets are separated, the droplets inevitably fall into the molten pool, so that the molten pool vibrates due to the velocity, volume, weight, etc. of the droplets, and the molten value and the wire melting portion are generated. Since the welding current value changes transiently due to the vibration of the arc, in order to eliminate the effect, at least 2
This is a method that employs an average value of more than one detected current value or detected voltage value. This process is performed by the groove width direction calculator 36 and the protrusion length direction calculator 37 to perform the above process. Next, even if the current value and the voltage value are acquired at the timing as described above, the detection method corresponds to the case where a minute short circuit occurs in the peak section. In such a case,
It mainly occurs when the distance between the chip base materials becomes short at both ends of the weaving. In such a case, since the current value as the arc component is smaller than the short-circuit component, the minimum detected current value is adopted as the positional deviation information in the groove width direction detection section, and the above processing is performed. .

Further, in the conventional welding profile control, the LPF is used.
The welding current value passed through the (low-pass filter) was calculated, and the position information was acquired from the change in the current. in this case,
In the detection of the current value, the current value is detected at the timing of the weaving signal on the robot control side, that is, at both ends and the central portion of the weaving signal. However, in this case, since the short-circuit current value is included in the current value component in addition to the current value associated with the wire protrusion length as the positional deviation information, accurate welding copying control cannot be performed. Therefore, in the embodiment of FIG. 4, the detected current value used as the positional deviation information is set to a preset time t1 from the rise of the peak current of the pulse welding power source.
By detecting after a lapse of time, only the arc current is taken in to detect the current value associated with the wire protrusion length change, and highly accurate welding profile control that is not affected by disturbance such as short-circuit current is performed.

That is, in FIG. 4, the pulse welding power source 57 controls the current with a current waveform as shown in FIG. The welding power source 57 sends the signal 10 to the peak signal transmitter 56.
Outputs 1. The peak signal transmitter 56 that receives the signal 101 outputs the peak signal 102. The peak signal 102 is sent to the position correction amount creation unit 55, and the position correction amount creation unit 55 detects the current value 103 from the current detector 58 after t1 time has elapsed since the arc signal 102 was input. Store. The current value detection operation is performed during a certain fixed time T, and after the fixed time T ends, the position correction amount creation unit 55 determines whether to perform position correction based on the stored current value. . When the correction is performed, the correction signal 104 is output to the torch drive control unit 54. The torch drive control unit 54 sends an operation command 105 to the torch drive unit 53 based on the correction signal 104, and the torch drive unit 5
Reference numeral 3 controls the trajectory of the torch 52 with respect to the work 51.
If the position is not corrected, do nothing. In this way, there is an effect that highly accurate welding contour control can be performed without being affected by disturbance such as short-circuit current.

[0014]

As is apparent from the above description, the arc welding profile control method using the pulse welding machine of the present invention is based on the pulse peak signal from the pulse welding machine power source. The current value detected only in the peak section, not in the section, and in the section with a very high probability as position information at the peak section is taken out, and the current obtained in the groove width direction detection section and the wire protruding direction section Since the average value is used only for the minimum value and the detected current value or detected voltage value distribution with or without positional deviation is selected and the detected value selected at the timing of the pulse interval is used, The positional deviation information can be stably obtained without being affected by the short circuit, and the welding line can be accurately followed.

[Brief description of drawings]

FIG. 1 is a control block diagram showing an embodiment of the present invention.

FIG. 2 is a welding current waveform and a melting state diagram of the tip of the welding wire in the case of the welding wire a.

FIG. 3 is a welding current waveform and a melting state diagram of the tip of the welding wire in the case of the welding wire b.

FIG. 4 is an explanatory diagram showing a welding copying system according to an embodiment of the present invention.

5 is a chart diagram of a current waveform, a peak signal, and a current detection process in the system of FIG.

FIG. 6 is a control block diagram of a conventional method.

[Explanation of symbols]

1: Torch, 2: Welder, 3: Robot controller, 3
1, 32: A / D converter 33, 34: Integrator 35: Detection command device 36: Groove width direction calculator 37: Wire protrusion length direction calculator 38:
Detection section commander 39: Weaving calculator 40: Phase correction value storage unit 41: Robot operation control system 42: Peak pulse internal timing command device 43: Peak pulse internal timing command value storage unit 51: Work 52: Torch 53: Torch drive Part 54: Torch drive control part 55: Position correction amount creation part 56: Peak signal transmitter 57: Welding power supply 58: Current detector 101: Signal 102: Peak signal 103: Current value 104; Position correction information 105: Operation command

Front page continuation (72) Inventor Seiichiro Fukushima 2-1, Kurosaki Shiroishi, Hachimannishi-ku, Kitakyushu, Fukuoka Prefecture Yasukawa Electric Co., Ltd.

Claims (5)

[Claims] 1. In a control method in an automatic welding copying apparatus that follows an welding line while swinging or rotating an electrode by using an arc welding method, a pulse peak start signal P1 is received from a pulse welding machine at the rise of a peak current. , The pulse peak end signal P at the falling timing
2 is received, the pulse interval between the pulse peak start signal P1 signal and the pulse peak end signal P2 signal is set as a pulse interval, and the current value in the pulse interval is detected at a preset cycle, and the obtained detected current value is detected. The current value selected at the preset timing in the detected current value,
A profile control method in an automatic welding profiler, which uses position information of a groove radial direction and a wire protrusion direction. 2. A copying control method in an automatic welding copying apparatus according to claim 1, wherein an average of at least two or more detected current values in the pulse section is used as position information as a detected current value. . 3. The position information in the groove width direction is a groove radial direction detection section which is detected at both ends of the groove of the rocking or rotating operation, and the position information in the wire protruding length direction is rocking or swinging. In both of the detection sections which are the wire protrusion length direction detection sections detected at the central portion of the rotation operation, the minimum detected current value in each section among the detected current values is used as the position information. A copying control method in the automatic welding copying apparatus according to claim 1. 4. Welding is carried out in the case where there is a positional deviation in the groove width direction and the wire protruding direction from the actual welding line, and the detected current values in the pulse section and both detection sections are measured by welding. Once stored, find the distribution of the detected current value when there is a position deviation and the distribution of the detected current value when there is no position deviation, and set the timing within the pulse interval to acquire the detected current value so that the two distributions are the most different. 2. The position information is selected as the detected current value in the pulse section and the detected current value in both detection sections based on the detected current value obtained at the selected timing. Control method in the automatic welding copying apparatus of the present invention. 5. In a copying control method in an automatic welding copying apparatus that follows a welding line while weaving an electrode by using an arc welding method, a current value used as position information is preset from a rise of a peak current of a pulse welding power source. 2. The copying control method in the automatic welding copying apparatus according to claim 1, wherein the detection is performed after a lapse of time t1.