JPH0429474B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention performs arc welding from a predetermined teaching point to the next teaching point over multiple layers, and for at least the first layer, the welding torch is moved to a predetermined position. The present invention relates to a multilayer welding method in which arc welding is performed from a predetermined teaching point to the next teaching point while swinging in the groove width direction in a swinging pattern.

(Prior art) Conventionally, in the aforementioned arc welding, the positional deviation of the welding torch is detected based on changes in the welding current signal while the welding torch is oscillating, and the welding torch is made to follow the welding line by correcting this positional deviation. Welding method (hereinafter referred to as "earn sensor")
There is.

However, in multi-layer welding, although the arc center described above can be used for the first layer, this arc sensor cannot be used for the second and subsequent layers because they are affected by the weld bead, and accurate tracing cannot be performed. One of the attempts to overcome this drawback is a welding method as disclosed in Japanese Patent Application Laid-Open No. 188572/1983. In the case of this welding method, when welding the first layer, the coordinates actually passed by the welding torch at each teaching point are stored in the storage means, and
When welding subsequent layers, the welding path is determined by interpolating the coordinates obtained by adding a predetermined shift amount to the actually measured coordinates stored above at each teaching point using an appropriate line.

(Problems to be Solved by the Invention) In the case of the welding method disclosed in the above-mentioned Japanese Patent Laid-Open No. 58-188572, only the teaching point can be reflected in the first layer from the second layer onwards. Therefore, when the distance between teaching points is long, the cumulative correction by the arc sensor during that time becomes large, and the position correction at each teaching point from the second layer onwards is rapid, distorting the bead shape.

(Means for solving problems and their effects) The multilayer welding method according to the present invention detects the positional deviation of the welding torch every time a swing pattern is executed during welding of the first layer, and changes the position of the welding torch by the detected amount. Welding is carried out while making corrections, and at the same time, each predetermined number of times the oscillation pattern is performed, the cumulative detected amount of positional deviation that has occurred for each oscillation pattern during the predetermined number of times is memorized. Every time the welding torch moves a distance corresponding to the distance of movement of the welding torch in the welding line direction by a predetermined number of swing patterns when welding a layer, the distance from the predetermined teaching point is determined during welding of the second and subsequent layers. Welding is performed while correcting the position of the welding torch by the cumulative detection amount at a position corresponding to the position of the welding torch. Therefore, an additional operation required during teaching is to set the predetermined number of times N _T of the rocking pattern. This N _T
The smaller the value, the better the followability of welding passes for the second and subsequent layers, but the optimum value is determined by considering the expected individual differences between workpieces, workpiece installation errors, the amount of positional deviation due to thermal distortion, and the memory capacity of the storage means. Determine.

(Example) Hereinafter, a detailed description will be given based on the embodiments shown in the drawings.

1 is a rectangular coordinate (X-axis, Y-axis, Z-axis) type welding robot adopted in carrying out the present invention, and is capable of rotating around the vertical axis 2 (arrow α) at the lower end of the vertical axis 2 configured at the terminal. A first arm 3 is attached to the end of the first arm 3, and a second arm 5 is attached to the tip of the first arm 3 so as to be pivotable about an oblique axis 4 (arrow β). Furthermore, the second
A welding torch 6 (MIC welding torch in this embodiment) as an end effector is attached to the tip of the arm 5. The central axis 2a of the vertical shaft 2, the oblique axis 4, and the central axis 6a of the torch 6 are configured to intersect at a point P, and the point P is connected to the torch 6.
This is made to coincide with the welding operating point of the tip of the electrode 7 protruding from the Thus, by controlling the rotation angles in the α and β directions, the attitude angle θ and the turning angle Ψ (so-called Euler angle) of the torch 6 with respect to the vertical axis 2 can be controlled by fixing the point P.

8 is a welding power supply device; 9 is an electrode supply device attached to the welding power supply device 8, which rotates a feed roller (not shown) to supply the electrode 7 to the torch 6; A welding power source 10 and a current detector 11 are connected in series between the workpiece W and the workpiece W.

Reference numeral 12 denotes a known computer as a control means for comprehensively controlling the entire welding robot 1. The computer 12 includes a CPU and memory,
The bus line B of the computer 12 is connected to the power supply 1.
0 and a current detector 11 are connected.

Bus line B is further connected to the X-axis servo system SX of robot 1, and this servo system SX
It includes the shaft power MX and an encoder EX that outputs its position information. Similarly, bus line B has Y-axis servo systems SY and Z configured in the same way.
Axis servo system SZ, α-axis servo system Sα, and β-axis servo Sβ are connected.

Reference numeral 13 denotes a remote control panel, which includes a manual operation snap switch group SW for manually moving the torch 6, a speed command rotary switch SV for commanding speeds other than welding, and three types of modes (manual mode M, test mode). Mode selector switch SM for switching to TE and auto mode A), numeric keypad TK, condition setting selector switch SE for setting various conditions at each switching position described below by operating the numeric keypad TK, and operation in each mode. Start switch used to start teaching and import teaching contents into memory
Equipped with STA etc.

The changeover switch SE has seven changeover positions SE ₁ to SE ₇ as shown below.

(1) Switching position SE ₁ ...Equipped with three display lamps for linear interpolation "L", circular interpolation "C", and arc sensing "A _s ", press key numbers "1" to "3" on the numeric keypad TK respectively. You can make a selection by lighting up each indicator lamp.

(2) Switching position SE ₂ ...has a display section for the welding condition number WNo., and the welding voltage E, welding current I, and welding speed are stored in the memory of the computer 12 for each number in advance.
Vw is stored as a set, and can be called up by pressing the key number on the numeric keypad TK that corresponds to the desired set.

(3) Switching position SE ₃ ...Has a display section for the function number FNo. In this embodiment, by operating key number "7" of the numeric keypad TK, the current position of the welding torch 6 is set to a dummy instead of the teaching point of the movement position. Teach that it is a point.

(4) Switching position SE ₄ ...Has a display section for the correction method number AUXNo. In this embodiment, when the key numbers "01", "02", and "03" of the numeric keypad TK are pressed, the display shown in FIG. As shown in a, b, and c, the weld joint shapes of downward fillet, horizontal fillet, and rectangular groove can be selected.

(5) Switching position SE ₅ ...has a pattern display section, and in this embodiment, the swing pattern is set using a four-digit number. For example, the 4th to 1st digits are the amplitude m (movement distance in the groove width direction) of the swing pattern, and the height h (downward fillet and re-shaped opening as shown in Figure 2 a, b, and c). For the first part, it is the distance from the welding line to the swinging surface, and for the horizontal fillet, it is the leg length), pitch PC (the distance traveled in the direction in which the welding line extends during a half cycle of the swinging pattern, as shown in Figure 3) , the number of increments n (the number of movement divisions in a half cycle of the swing pattern, which determines the frequency), and each menu number is set.

(6) Switching position SE ₆ ...Equipped with a timer display section so that the stopping time at the left and right ends of the swing can be set using the menu number.

(7) Switching position SE ₇ ...Has a pattern number display section,
It is possible to set with a key number how many times (N _T ) of the oscillation pattern the cumulative detected amount of positional deviation of the welding torch detected by the arc sensor of the first layer L1 is to be stored in the memory.
In this embodiment, the memory takes in the cumulative value of the detected amount of positional deviation occurring in each rocking pattern in Nr rocking patterns as the cumulative detected amount. For example, when Nr=3, the detected amount of positional deviation in the first swing pattern is a, the detected amount in the second swing pattern is b, and the detected amount in the third swing pattern is c.
If so, a+b+c is taken into the memory as the cumulative detected amount. Here, the detected amounts a, b, and c are not necessarily positive numbers, and may be 0 or negative numbers. Furthermore, in the case of arc welding, the detected amounts a, b, and c are generally numbers on the order of 1/10 mm, such as 0.2 mm or 0.3 mm.

Now, as shown in Fig. 1, the workpiece W has a vertical member W2 temporarily attached to the upper surface of the elongated horizontal member W1, and the right-angled corner formed by these members W1 and W2 is moved from one end to the other. It is intended to be continuously welded in three layers up to the edge.

The teaching operation by the operator and the processing executed by the computer 12 in connection therewith will be explained below.

(T1) Select manual mode M by operating switch SM. Then, by operating the switch SW, the torch 6 is positioned at a teaching point _P0 , which is an arbitrary point near one end of the right angle corner. Next, change the selector switch SE to switch position SE ₁ , and press the numeric keypad.
By operating TK to set linear interpolation "L" and operating switch STA, computer 12 uses the position information (X ₀ , Y ₀ , Z ₀ , θ ₀ , and Ψ ₀ ) of teaching point P ₀ and linear interpolation. Take "L" as the first step.

(T2) Torch 6 is set to 1 by operating the switch SW.
Position the welding start teaching point _P1 of layer L1 in a posture suitable for welding.

Next, by operating the numeric keypad TK to set the arc sensing "A _s " while leaving the switching position of the changeover switch SE unchanged, and by operating the switch STA, the computer 12 will receive the position information of the teaching point _P1 and the arc sensing "A _s ". Take it in as the next step.

(T3) Move the torch 6 to any point within the coordinate quadrant surrounded by members W1 and W2 by operating the switch SW.
_P2 (referred to as dummy point).

Next, the switching positions of the changeover switch SE are set to SE ₁ , SE ₃ ,
In SE ₄ , set "A _s ", "7", and "02" respectively by operating the numeric keypad TK. Among these, FNo.
"7" is the designation of the dummy point, and AUX No. "02" is the designation of the horizontal fillet as the weld joint shape (second
(see figure). Furthermore, the switching position of the changeover switch SE is set to SE ₅ .
Now, use the numeric keypad TK to set the amplitude m, height h, pitch PC, and number of increments n that constitute the swing pattern described above using four-digit menu values. After that, by operating the switch STA, the computer 12 will take the position information of the dummy point _P2 , the arc sensing "A _s ", F No. "7", AUX No. "02", and the swing pattern information as the next step. take in.

(T4) Turn torch 6 to 1 by operating switch SW.
It is positioned at the welding end teaching point P ₃ (not shown) of layer L1 in a posture suitable for welding. Then switch switch
At SE switching positions SE ₁ , SE ₂ , SE ₄ , SE ₆ , and SE ₇ , "As" and "As" are selected by operating the numeric keypad TK, respectively.
Set “01”, “10”, “1”, and “3”. In this,
W No. "01" is the start teaching point P ₁ to the welding end teaching point
This is a menu number with the optimal welding conditions (welding voltage, welding current, etc.) up to _P3 . Furthermore, AUX No. "10" means that the position is corrected using swing pattern data obtained in advance from another work. Timer "1" specifies a menu number suitable for temporarily stopping the welding torch 6 at the left and right ends of the swing. Furthermore, N _T "3" means that the cumulative detection amount detected by the arc sensor is loaded into the memory every third time the pattern is completed. Now, if you operate Switch STA, computer 1
2 takes in the position information of the welding end teaching point _P3 , arc sensing "A _s ", W No. "01", AUX No. "10", timer "1", and N _T "3" as the next step.

(T5) By operating the switch SW, position the torch 6 at an arbitrary retreat teaching point _P4 that can be moved linearly from the welding end teaching point _P3 . Then, switch the selector switch SE to switch position SE ₁ , and press the numeric keypad.
If you set linear interpolation "L" by operating TK and operating switch STA, the computer 12 will
Take in the position information of _P4 and linear interpolation "L" as the next step.

The teaching of the first layer L1 has been described above, but the second layer L2 and the third layer L3 are taught in the same way. To explain only the points that are different from the first layer L1, in (T2), the arc sensing "A _s " is selected using only the position information of the welding start teaching points P ₅ and P ₇ of the second layer L2 and the third layer L3. Remove from. At (T3), remove the arc sensing "A _s ", and at (T4), remove the 2nd layer L2 and 3
Instead of teaching the position information of welding end teaching points P ₆ and P ₈ (both not shown) of layer L3 and removing arc sensing “A _s ”, AUX No. “10”, and N _T “3”, For example, select AUX No. "11". This AUX No.
"11" reads out the cumulative detection amount stored in the memory every N _T number of patterns taught in the first layer L1, every Nr of the same pattern in this second layer L2 and third layer L3, This means that the position is corrected using this cumulative detected amount.

This completes the teaching work. When proceeding to automatic welding, first set the switch SM to auto mode A, and operate the switch STA to continuously execute the program created by the teaching described above. The flow of processing executed by the computer 12 at this time is shown in the flowchart of FIG.

Welding robot 1 performs the following operations based on command output from computer 12. First, the torch 6 is positioned at the teaching point _P0 , and the torch 6 is moved by linear interpolation toward the welding start teaching point _P1 of the first layer L1. When the torch 6 reaches the teaching point _P1 , the processing PR
6, arc weaving is started, and horizontal fillet welding is performed toward welding end teaching point _P3 based on welding condition W No. "01". The movement locus of the torch 6 at this time will be explained with reference to FIG.

The computer 12 creates and outputs an isosceles triangular swing pattern PT whose base is the pattern reference line PL1 connecting welding start teaching point P ₁ and welding end teaching point P ₃ as the first swing pattern (N=1). do.

Therefore, in process PR7, the torch 6 moves from teaching point P ₁ → point P ₁₁ → point P ₁₂ , and the computer 12
During the movement, the arc sensor detects the positional deviation, so the point is further moved by the detected amount in the direction perpendicular to the pattern reference line PL ₁ from point _P12 .
Leading up to P ₁₃ .

The second execution swing pattern starts from point ₁₃ .
P ₁₃ →P ₁₄ →P ₁₅ →P ₁₆ (P ₁₅ →P ₁₆ is the detected amount of positional deviation)
Draw like this. The torch 6 moves as the third swing pattern from point P ₁₆ → P ₁₇ → P ₁₈ → P ₁₉ (P ₁₈ → P ₁₉ is the positional deviation detection amount), and when it reaches point P ₁₉ , the computer 12 is N=3 in processing PR8
(=N _T ), and the cumulative detected amount △δ ₁ (distance from pattern reference line PL ₁ to point P ₁₉ ) as the sum of the detected amounts of each positional deviation in the swing patterns of N = 1 to 3. Import into memory.

Next, Torch 6 performs a new 1st, 2nd, and 3rd
Execute the oscillation pattern for the 3rd time and reach the 3rd end point P ₂₈
When the computer 12 reaches the new N=1 to 3
The cumulative detected amount Δδ ₂ (distance from the pattern reference line PL ₂ passing through the point P ₁₉ to the point P ₂₈ ) as the sum of the detected amounts of each positional deviation in the swing pattern is taken into the memory.

In this way, the computer 12 controls each _N
The cumulative detected amount as the sum of the detected amounts of positional deviation for =3 (=N _T ) times is taken into the memory as Δδ ₁ , Δδ ₂ , . . . Δδn.

After welding the first layer L1, the torch 6 welds the second layer L1.
Arc weaving welding is performed without an arc sensor from the welding start teaching point _P5 in step 2. That is,
Torch 6 is used for the first time (P ₅ → P ₅₁ → P ₅₂ ) and the second time (P ₅₂
→P ₅₃ →P ₅₄ ), the third swing pattern (P ₅₄ →P ₅₅ →P ₅₆ ) is executed, and when the point P ₅₆ is reached, the computer 12 performs processing PR17 to set N=3 (=N _T ).
The process moves to process PR19, reads out the first cumulative detection amount △δ ₁ stored in the memory, and uses this △δ ₁ to weld the current point P ₅₆ with the welding start teaching point P ₅ of the second layer L2. Pattern reference line connecting end teaching point P ₆
Outputs a command to correct the position in the direction perpendicular to PL ₁ ′. Therefore, the torch 6 moves from point P ₅₆ → P ₅₇ ,
Draw the next pattern starting from point P ₅₇ . Then, when a new N=3 (=N _T ) oscillation pattern is executed, the computer 12 again calculates the next cumulative detection amount
In order to read δ ₂ from the memory and output a command to correct the position at this △δ ₂ , the torch 6 moves to the current point P ₆₃
was displaced by △δ ₂ in the direction perpendicular to the new pattern reference line PL ₂ ′ connecting the point P ₅₇ and the welding end teaching point P ₆ .
Move to P ₆₄ and make corrections. In this way, the torch 6 is N=
Arc weaving is continued while correcting the position every 3 (=N _T ) swing pattern executions, and the second layer L
2 welding is completed. Regarding the third layer L3, 2
As with layer L2, without an arc sensor, N _T
Welding is performed while correcting the position each time the swing pattern is executed.

In addition to the embodiments described above, the present invention can also be modified as described below.

() In the above embodiment, the frequency of position correction for the second and subsequent layers was set to N _T =3, but the prediction of positional deviation due to individual differences in workpieces, installation errors, and thermal distortion,
You can set the number of times as appropriate depending on the size and shape of the swing pattern and memory capacity.
_NT may be 1.

() In Fig. 5, the shapes and sizes of the swing patterns of the first layer L1 and the second layer L2 are shown to be exactly the same, but if the pitch PC is the same, the amplitude m
The number of increments n can be arbitrarily set for each layer. As an extreme example, for the second and subsequent layers, the amplitude m may be set to "0" and welding without weeping may be performed. In this case, for the second and subsequent layers, it is not possible to specify the moving distance of the welding torch in the welding direction based on the number of swing patterns, so the welding torch is The moving distance in the welding direction is calculated, and each time the welding torch moves a distance corresponding to the calculated moving distance in the second and subsequent layers, the distance from the predetermined teaching point is calculated for the second and subsequent layers. The cumulative detection amount at a position corresponding to the position of the welding torch during welding is read from the storage means.

() In the above embodiment, the swing pattern has an amplitude m,
The pitch PC and height h are set by key input for teaching, but it is also possible to actually position the torch at the welding start point and teach one of the swing patterns using this welding start point as the starting point. good.

() Robots can also be implemented with mechanical configurations other than rectangular coordinate systems.

(Effects of the Invention) As explained above, according to the multilayer welding method of the present invention, the arc sensor is used to perform copy welding in the first layer, and the positional deviation is accumulated by the arc sensor every predetermined number of swing patterns. The detected amount was memorized, and from the second layer onwards, the cumulative detected amount was read out every time the welding line direction distance corresponding to the predetermined number of times was moved, and the position was corrected using this, so the arc sensor could not be used on the second layer. Even after welding, it is possible to perform trace welding as accurately as using an arc sensor.

[Brief explanation of drawings]

Fig. 1 is an overall schematic diagram of a welding robot that employs the multilayer welding method of the present invention, Fig. 2 is a schematic diagram showing various weld joint shapes, Fig. 3 is an explanatory diagram of the swing pattern, and Fig. 4 is a flowchart. , FIG. 5 is an explanatory diagram of the execution of the swing pattern. In the figure, 1 is a welding robot, 6 is a welding torch, 1
2 is a computer, 13 is a remote control panel, and W is a workpiece.

Claims (1)

[Claims] 1 Arc welding from a predetermined teaching point to the next teaching point is performed over multiple layers, and at least one
Regarding layers, in a multilayer welding method in which arc welding is performed from a predetermined teaching point to the next teaching point while the welding torch is oscillated in the groove width direction in a predetermined oscillation pattern, when welding the first layer, , the positional deviation of the welding torch is detected every time a swing pattern is executed, and the welding is performed while correcting the position of the welding torch by the detected amount; When welding each layer after the second layer, the cumulative detected amount of positional deviation that occurred during welding is stored, and when welding each layer from the second layer onwards, the distance corresponding to the movement distance of the welding torch in the welding line direction by a predetermined number of swing patterns during welding the first layer is stored. Each time the welding torch moves a distance, the cumulative detection amount at a position corresponding to the position of the welding torch during welding of the second and subsequent layers is calculated for the distance from the predetermined teaching point.
A multilayer welding method characterized by performing welding while correcting the position of the welding torch.