JPH0380590B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a trackless self-propelled trolley suitable for continuous horizontal fillet welding around four circumferences of a box-shaped structure.

BACKGROUND TECHNOLOGY When welding ship hulls or bridges, welding often involves welding the corners of steel plates assembled into a box shape. 1st
The figure shows an example of this, in which numeral 1 is a horizontal member, which in the case of a ship's hull would be the bottom of the ship, and numerals 2 and 3 are vertical members, which are reinforcing materials. Vertical members 2 and 3 extending vertically and horizontally
and the horizontal member 1 constitute a rectangular parallelepiped box-shaped structure,
Horizontal fillet welds are made at the abutting portions of these vertical and horizontal members.

Several shapes of self-propelled carts have been considered for performing horizontal fillet welding of such box-shaped structures. Generally, a self-propelled trolley equipped with a pair of tracing rollers and a welding torch only performs welding on straight sections, and when it comes to a corner, it changes direction by input and welds the next straight section. However, with this method, there is a portion at the corner that cannot be welded, that is, a portion that cannot be welded for the length of the self-propelled cart, that is, a portion left unwelded. Therefore, a self-propelled truck has been proposed that eliminates this welding residue and performs intermittent welding or continuous welding on all four circumferences.

An example of intermittent welding is to install a mechanism for rotating or parallelly moving a welding torch on a self-propelled trolley equipped with a pair of copying rollers, and to weld while welding in a straight line in a manner that minimizes the amount of weld left behind during straight welding. When proceeding to straight line welding on a vertical member corresponding to the front wall surface of the front wall, the arc is stopped, the copying roller is retracted and the direction of the cart is changed, and then the copying roller is reset to weld the straight line of the vertical member on the front wall surface. Some require welding.

As an example of four-circle continuous welding, as shown in Fig. 1, it is installed on the welding line side of the self-propelled trolley 4, and is moved between the locked position (shown by the solid line) and the unlocked position (shown by the solid line) against the spring. a pair of guide arms 5 for copying travel which take a position rotated rearward from that point (the state shown by the broken line), and a pair of drive wheels provided on both sides of the truck, one of which is brought into contact with and separated from the motor by an electromagnetic clutch. 6, is provided on the bottom center of the trolley, and is deenergized.
The electromagnet 7 is attracted to the running surface by force, and is released and becomes the center wheel of the cart spin at the intersection of the welding lines.
There is a self-propelled truck that is attached to the truck and includes a welding torch moving device 9 that advances the welding torch 8 toward the welding line (arrow A) and moves it back from there, a front wall detector 10, and casters 11. Straight line welding with this truck is performed while tracing the side plate 2 with the guide arm 5. When the self-propelled truck 4 hits the front wall surface 3, the guide arm 5 is unlocked by a signal from the front wall detector 10, and the electromagnet 7 is attracted. Welding is carried out while moving the welding torch 8 forward and backward by the moving device 9 under computer calculation control according to the rotation angle of the trolley. After 90° rotation welding, the process moves to the above-mentioned straight line welding of the side plate 3 part, and the same goes for four consecutive circumferences. Perform welding.

In a self-propelled truck that performs such continuous or intermittent welding, the guide arm 5 for traveling along the side wall plays an important function. That is, the pair of guide arms 5 allows the carriage 4 to move along the welding line, so that the torch 8 can always aim correctly at the welding line. however,
This copying device has the following problems. That is,
When welding in a straight line, horizontal member 1 and side wall surface 2
If the angle between the is maintained and there are no particular problems. However, if the side wall surface 2 is inclined outwardly or inwardly relative to the horizontal member 1 depending on its location, and the guide arm 5 contacts the side wall surface at a point that has a certain height above the horizontal member 1, then the truck will not align with the weld line. approach or move away, and the welding torch 8
The target position moves forward or backward by ΔR with respect to the weld line, and the fillet weld bead no longer has equal leg length, and in extreme cases, an undercut or undercut bead appears on the side wall surface, resulting in a defective weld.

In addition, a limit switch is used as the side wall detector 10 that detects when the traveling truck hits the front wall surface, and this detects the front wall surface and spins the truck,
When changing the running direction, if the front wall surface is tilted with respect to the horizontal member, the welding torch will still deviate from the aimed position, and unless corrected, a good fillet weld bead will not be obtained. This is a problem because it is required to always accurately maintain the aiming position of the welding torch in fillet welding with long legs due to the recent downsizing of shipbuilding.

Furthermore, such a simple limit switch mechanism has the following problems. In other words, if the angle between the side wall surface 2 and the front wall surface 3 is completely 90 degrees, the rotation angle of the cart at the corner may be 90 degrees, and with this 90 degree rotation, it is possible to move on to the next straight section welding. Less than or equal to 90°
If it is more than 90°, the required rotation angle of the cart is 90° or more.
The following is true. In addition, if the angle formed by the side wall surface 2 and the front wall surface 3 is 90°, the center position of the rotation axis of the cart at the corner is on these sides, on the corner of the square that includes the front wall surface (side, on the opposite side of the corner where the front walls intersect) angle), but if it is more than or less than 90°, it will shift back or forth. With a simple limit switch mechanism, when the limit switch comes into contact with the front wall, it simply rotates 90 degrees.
The above points cannot be corrected. One solution to this problem is to temporarily fix the side walls and front wall so that they intersect at a correct 90° angle, but in large structures it is difficult to obtain the right angle. be. However, since it is rare for a deviation from 90° to be significant, it is not unthinkable to ignore deviation from 90° as an error. It has been found that when the rotation angle of the cart 4 is kept constant at 90 degrees with the same lock type, the guide arm 5 cannot be locked after rotation, and it may not be possible to shift to stable side wall surface tracing.

OBJECT OF THE INVENTION The present invention solves such problems and provides accurate control of the trolley and torch even when the vertical members change their inclination angle with respect to the horizontal members, and even when the angle between the vertical members is not a perfect right angle. Weld line copying and corner rotation are performed.
It is an object of the present invention to provide a trackless self-propelled truck for welding that can shift to stable side wall surface following movement after corner rotation and can always perform good fillet welding.

Composition of the Invention The present invention provides a side wall surface copying mechanism having a pair of rotatable and lockable guide arms projecting laterally from the front and rear sides of the bogie, a front wall surface detection mechanism, and a weaving mechanism for weaving the tip of a torch with respect to a welding line. It is equipped with a torch swinging mechanism and a control device, and when it detects the front wall while tracing the side wall, it changes the traveling direction and continues tracing the front wall using the front wall as the side wall, and during this time it continuously traces the horizontal fillet. In a trackless self-propelled trolley for welding a box-shaped structure, the front wall surface detection mechanism includes a limit switch, a potentiometer, and an operating end of the limit switch disposed opposite to the front wall surface. The operating end of the potentiometer is arranged laterally apart, the torch swinging mechanism is equipped with a weaving end detection mechanism, and the control device is configured to detect the operating end of the limit switch while the trolley is moving straight from the side wall surface copying mechanism. When the potentiometer hits the front wall and detects the front wall, the front wall inclination angle is calculated based on the amount of retreat of the operating end of the potentiometer that hit the front wall and retreated, and the cart is moved to a predetermined angle according to the inclination angle. The present invention is provided with a means for rotating the welding current at an angle and moving the torch forward or backward so that the fluctuation state of the welding current value at the weaving end reaches a predetermined state so that the torch follows the welding line while weaving. Next, this will be explained with reference to examples.

Embodiments of the Invention The present invention is applicable when the angle (tilt angle) formed by the vertical member with respect to the horizontal member is not 90°, and when the angle (tilt angle) formed between the vertical members (side wall member and front wall member) is 90°.
First, countermeasures against tilting of the side wall surface will be explained. In Fig. 2, 1 is a horizontal member, 2 is a side wall member, and 4 is a horizontal member.
0 is a copying roller attached to the tip of the guide arm 5. If the welding torch 8 is set correctly as shown in the solid line when the side wall 2 is perpendicular to the horizontal member 1 as shown by the solid line, the side wall member will be tilted as shown by the broken line 2', that is, the side wall 2' will be perpendicular to the horizontal member 1. If it falls inward by an angle α with respect to 1, it will copy at the height H from the top surface of the horizontal member 1 to the copying roller 40, so when viewed from the welding line 1a, the traveling trolley 4 has retreated by a distance Δx, and the welding The torch 8 deviates from the correct position by a distance ΔR. To prevent this, it is necessary to move the torch forward by a distance ΔR and correct the torch to the position 8' shown by the broken line.

In order to perform this correction, the present invention utilizes the current of the welding torch that performs weaving. Figure 3~
To explain this with reference to FIG. 9, FIG. 3 shows an example in which the torch 8 is swung parallel to the horizontal member 1 as shown by the arrow 100, and FIG.
An example is shown in which a torch swinging mechanism (not shown) is mounted on the movable plate 16 in FIG. 5, as shown in FIG. show. P ₀ P indicates the center of these fluctuations. FIG. 5 shows a torch swinging mechanism attached to the traveling carriage 4, and 15 is a torch holder with a movable plate 1.
6, and 19 is a frame that is attached to the trolley 4 and supports the pair of guide shafts 17 and feed screw shaft 18 of the movable plate 16, their drive motor 13, potentiometer 14, and the like. When the motor 13 rotates, the feed screw shaft 18 also rotates, and the nut member (not shown) of the movable plate 16 that is threadedly engaged with the feed screw shaft moves, and as a result, the movable plate 16, the torch holder 15 attached thereto, and the nut member (not shown) of the movable plate 16 are moved. The torch 8 moves. When the motor 13 is rotated in the forward and reverse directions, the torch 8 swings, and this swinging motion is caused by the reference signal and the potentiometer 14.
Feedback control using the current torch position output by the controller as a feedback signal allows the control to be performed at any amplitude and speed.

Since we use a welding power source with constant voltage characteristics,
As shown by straight line B in FIG. 9, power supply voltage V exhibits a substantially constant value regardless of welding current A. Curves l ₁ , l ₂ ,
l ₃ shows arc voltage and current characteristics when the arc lengths are l ₁ , l ₂ , l ₃ (here l ₁ > l ₂ > l ₃ ), and the intersection of these curves and power supply characteristic B is the operating point. Become. Now, if the normal operating point is voltage V ₂ and current A ₂ , then if the arc length becomes larger than this (when l ₂ becomes l ₁ ), the current will be
When A decreases to ₁ and becomes small (if l ₂ becomes l ₃ ), the current increases to A ₃ . Because of this relationship, when the torch 8 is oscillated as shown in Fig. 3, the welding current A changes as shown in Fig. 6, and when the torch 8 is oscillated as shown in Fig. 4, the welding current A changes as shown in Fig. 7. It fluctuates like that.
That is, in the case of Fig. 3, since the torch 8 moves in parallel from the position _P1 to beyond _P0 , there is no change in the distance between the torch tip and the members 1 and 2, and the current A is almost constant (however, (high frequency components are removed)
However, when the torch aiming position comes to be on the vertical member 2, the distance becomes shorter, so the welding current increases and reaches its maximum at the swing end _P2 . After that, it decreases, then increases again, and repeats this as the torch oscillates. In the case of Fig. 4, the torch oscillation plane is inclined, so when the torch 8 aims at the welding line (the intersection of 1 and 2), the above-mentioned interval is at its maximum, and even if it deviates in any direction, the above-mentioned interval becomes smaller. Therefore, the welding current A peaks at the swing limits P ₁ and P ₂ as shown in FIG.

Therefore, when the torch is oscillated parallel to the horizontal member 1 as shown in Fig. 3, the oscillation amplitude is constant but the oscillation position is variable, and when the torch is moved from P ₁ to P ₂ direction, the welding current is The torch is advanced until it becomes equal to the current value at the swing end _P2 when the torch aiming position is normal, as shown in Fig. _6A5 , and at this position it is moved back by a predetermined swing width, and at that point it is reversed. When the oscillation control is performed, the torch 8 automatically always follows the welding line while weaving. Alternatively, the swinging can be performed autonomously, and the current value _A5 at the swinging end _P2 on the vertical member side is compared with the set value As, and As
If it is smaller (or larger), the next vertical member side swing limit is advanced (or retracted) by a certain value Δx, and A ₅
You can make the torch follow the welding line by repeating this until it becomes As.

In the case of Figure 4, find the current values A ₆ and A ₇ at the swing ends P ₁ and P ₂ when the torch aiming position is normal, and then reverse the swing direction when the current reaches these values. By doing so, the torch can be made to follow the welding line. Alternatively, the current difference ΔA=A ₆ −A ₇ may be monitored, and when this becomes small, the torch is moved backward, and when it becomes large, the torch is moved forward. That is, when the swinging torch approaches the vertical member 3, the current A ₇ at the position P ₂ increases, so ΔA becomes small, and in this case, the torch can be moved backward. When the torch moves away from the vertical member, the opposite is true; _A7 decreases, so the difference ΔA becomes large; in this case, it is sufficient to move the torch forward. The amount of forward and backward movement can be set as a unit amount, and a method such as continuing forward and backward movement until the normal value is reached can be used. In general, it is better to aim the torch in horizontal fillet welding so that the center of the swing width is approximately 1 to 2 mm in front of the weld line for better results in terms of isolateral fillet leg length, etc. Therefore, it is preferable to set the current value in consideration of this point.

If the vertical member 2 falls inward as shown at 2' in Fig. 8, the torch must move forward, and if it falls outward as shown at 2'', it is necessary to move the torch back. It is also compatible with the torch, allowing for accurate torch tracing.

When the trolley 4 rotates at the corner of the vertical members 2 and 3, the torch must move forward, and when it passes the corner, it must retreat, and this forward and backward control can also be performed automatically by the above-mentioned current monitoring.

The rotation angle of the truck at the corner differs depending on whether or not the members 1 and 2 are perpendicular to each other, as described above. To explain this point with Figure 10, Figure 10a
is the case where the angle between the side wall surface ′ and the front wall surface ″ is wider than 90 degrees by δθ degrees, and Fig. 10 b shows the side wall surface
It is a diagram illustrating the rotation center of the self-propelled bogie and the rotation angle relationship when the angle between AB'' and the front wall surface B''D'' is narrower than 90 degrees by δθ degrees. O is the rotation center of the self-propelled bogie, and A is the start of rotational welding. If the side wall surface is AB and the front wall surface is BD, and the angle ABD formed by these walls is a right angle, then point A is BA=OA, quadrilateral ABCO is a square, and point O is This is the corner of the square opposite to corner B. If the cart is rotated by θ _E = 90 degrees around point O, the tip of the welding torch will draw an arc AC, and will follow the front wall BD from point C. Tracing travel and straight line welding on the front wall are possible, but if the front wall
If AB′D′ is (90° + δθ) or AB″D″ is (90° − δθ) in B′D′ or B″D″, the cart rotation angle is θ _E ′ = 90° for the former. −δθ, the latter is θ _E ″=90°+
δθ
The former is C′, and the latter is a straight line welding along the front wall after C″. Here, C′ and C″ are
Two straight lines AB′ intersect with circles with radius OA
This is the point where B'D' or AB'' and B''D'' are in contact, and the bogie rotation center O needs to be selected in this way, that is, so that a circle with radius OA is inscribed in the two intersecting straight lines.
Since this change in the center of rotation and the rotation angle is caused by a deviation from 90° in the angle between the side wall and the front wall, it is necessary to detect the front wall inclination angle in order to correct this change.

To measure the front wall inclination angle, for example, place two
Attach the arms of the book horizontally so that when they hit the front wall, they will be pushed back, and find the difference in arm protrusion length when both arms hit the front wall. Bye. However, with this method, it is difficult to determine the position of the rotation center O. FIG. 11 shows a detection device that allows the position and inclination angle of the center of rotation O to be easily determined. As shown in FIG. 10, the basics of the device shown in FIG. 11 is that a limit switch LS (more specifically, the operating end of the limit switch LS) is mounted on a straight line passing through the center of rotation O of the cart and parallel to the side wall, so that the above-mentioned point C etc. can be detected. In addition, a potentiometer POT (similarly, this is its operating end in detail, but this will be omitted from the explanation as appropriate) is installed at a position laterally shifted from this point, so that it is possible to detect points such as point D, and these POT and This is because the LS is linked.

The limit switch LS is set to close when it comes into contact with the front wall, the potentiometer POT is movable in a straight line parallel to the side wall, and is always in a protruding state due to a spring. Since the deviation (deviation) is within ±10°, the POT should be set so that it contacts the front wall first even at the maximum inclination angle. As is clear from Fig. 10, when the front wall forms an angle of 90°±δθ with the side wall, the LS operating position must be advanced by ΔC from the position C when the angle is 90°. ∆C forward movement is performed by the POT protruding forward from the LS being pushed backward by the bogie movement.

In FIG. 11, 20 is a detector base, to which a sliding bearing 21 is fixed, and a front wall detection roller RD,
The support 22 and a pair of sliding shafts 23 are supported by the bearing 21 so as to be movable back and forth. A spring 24 is attached to one of the sliding shafts between the support 22 and the bearing 21, and keeps the roller RD etc. in a protruding state at all times. POT is the aforementioned potentiometer, and its fixed part is fixed to the base 20, and its movable part is attached to the support 22.
The protrusion length of the roller RD is measured.
A sliding bearing 28 is also fixed to the base 20, and a sliding piece 30 having a sliding shaft 29 is movably attached thereto, and the aforementioned limit switch is attached to this sliding piece.
The LS is fixed and the front wall detection roller RC, its support 26 and sliding striker 27 are movably mounted. Gears 33, 34 and a cam 37 are further attached to the base 20 by shafts 35, 36,
These gears mesh, and gear 33 meshes with a rack 32 attached to the other side of the sliding shaft 23,
The cam 37 rotates together with the gear 34. This cam 37 is always in contact with the end surface 38 of the sliding piece 30,
This is due to a spring 39 mounted on the sliding shaft 29 between the bearing 28 and the end face 38.

The rack 32, gears 33, 34, and cam 37 are used to interlock the POT and LS. That is, the spring 24 causes the POT operation roller RD to
protrudes, and as a result, the LS operating roller RC also protrudes via the rack, gear, and cam mechanism, but is at a position retreated from the roller RD. This is Laura
RC and RD are not in contact with the front wall. When the cart moves forward in this state and approaches the front wall, the first thing it comes into contact with is the roller RD, and as the cart moves forward, the roller
As RD retreats, roller RC also retreats, but if the front wall inclination angle is 90° or more, roller RC will eventually come into contact with the front wall, and limit switch LS will also turn on. At this time, the cart starts rotating, reads the output of the potentiometer POT to determine the protrusion length, calculates the front wall inclination angle from this, and determines the angle θ _E , etc. at which the cart should rotate.

When the front wall inclination angle is 90°-δθ as shown in Fig. 10b, the retreat of roller RD continues even if RC and RD are laterally aligned, and after roller RC is laterally aligned with RD, It stops moving backwards and moves forward, eventually hitting the front wall and turning on the limit switch LS. Now the cart starts rotating, potentiometer
The reading of POT, etc. is performed in the same way as in the above case. If the front wall is perpendicular to the side wall, when rollers RC and RD are lined up, roller RC will also come into contact with the front wall, the limit switch LS will be turned on, and the cart will start rotating.

In the above description, it is assumed that the front wall is perpendicular to the horizontal member, but if the front wall is tilted with respect to the horizontal member like the side wall 2, it is necessary to correct the torch tracing position. This is done by current tracing as explained in FIGS. 3 and 4. Note that the correction of the position of the rotation center for the deviation δθ of the inclination angle from 90° is small, and when the directional running angle of the traveling trolley 4 is set to 4 degrees, the deviation δθ is ±
It was found that no correction is necessary for angles up to about 3 degrees, and therefore no front wall inclination angle detection function is required, and only the front wall detection limit switch LS is required. In particular, if the tip of the welding torch is made to follow the above-mentioned current, the deviation will be automatically corrected and will not adversely affect the bead shape.

In this way, in the bogie of the present invention, the welding torch movement locus due to the side wall tracing run and the bogie spin at the corner portion is used as the basic trajectory, and the welding wire target position is corrected by current tracing control when the vertical member is tilted or tilted. , horizontal fillet welding with good isopodality is performed continuously on the weld line following the straight running part, corner rotation part, and straight running part. Note that if there are scallops at the corners, such as in shipbuilding parts, current tracing alone cannot be applied, but in this case, measures such as skipping the scallops on the basic torch movement trajectory and then starting welding by current tracing again are recommended. Just take it.

FIGS. 12 and 13 are flowcharts showing the operation procedure of the control section for making such corrections.
Fig. 12a shows an example of the current tracing correction using the current values at the _two points P, where the welding current _A5 at _{the two} points P is taken in and the difference ΔA from the reference value As is calculated.
If = 0, the target position deviation Δx is 0 and no correction is made, and if ΔA is positive or negative, the torch is set forward and the amount of backward movement is set to Δx. Figure 12b shows the current values at the _P1 and _P2 points.
An example of using A ₆ and A ₇ is shown, and the difference ΔA = A ₆ - A ₇ is calculated. If it is the reference value As, Δx = 0, and if ΔA > As or ΔA < As, the torch is forward and the backward movement amount is set to Δx. do.

A potentiometer (not shown) is attached to the cart 4, with a stator and a movable element attached to the shaft of the electromagnet 7 in FIG. 1 and the cart 4, and this potentiometer outputs the cart spin angle θ. do. 1st
As explained in Figure 0, the necessary bogie spin angle θ _E at the corner depends on whether the front wall inclination angle is 90°, 90° + δθ, or 90
°
−δθ, respectively, θ _E =90°, θ _E ′,
θ _E ″, but in both cases, the amount of torch aiming position correction (this means that the torch tip is not aiming at a circle with radius R, but rather aiming at two intersecting straight lines ABC, AB′C′, AB″C″) (This is not the correction amount for the tilt angle of the vertical member) ∆l increases until θ _E /2 and decreases thereafter. Therefore, when correcting the torch aiming position by detecting the front wall inclination angle instead of current tracing, θ _E /2
It is necessary to change the correction procedure after this point. 13th
The judgment block θ90°±δθ/2 in figure a checks this boundary, and up to the boundary (Y) is Δl
=R(1/cos θ-1), and after the boundary (N), the correction amount (torch movement amount) Δl is calculated as Δl=R{1/sin(θ-δθ)-1}. To correct the torch aiming position by tilting the side wall or front wall, the rotation radius R is R+
It can be processed as if the correction amount was (Δx ₁ +Δx ₂ +...). Of course, Δx will be negative if the side walls fall outward. Figure 13b shows a routine to instruct the cart to finish spinning, and the cart spin angle θ is the required angle θ _E
If so, a spin stop is commanded and the flag F is reset to 0.

FIG. 9c shows a routine for correcting the welding speed. If the torch is aimed at two intersecting straight lines ABC, etc., and the cart spin speed is constant, the welding speed will vary greatly (maximum at corners). To prevent this, it is best to adjust the cart spin speed so that the welding speed is constant, and FIG. 13c shows such control. Again, detect the spin angle θ, check whether it is before or after (90°±δθ)/2, and if it is before (Y) then set the bogie spin speed v to v=rV ₀ /Rcos ² θ, if it is after (N ) This is set as v=rV ₀ /Rsin ² (θ−δθ), and this is output as the command speed. However, r indicates the distance between the cart spin center 0 and the wheel 6 as shown in FIG.

Figure 14 shows the control device mounted on the traveling trolley 4.
The main parts of CNT are shown. 50 is a welding current detection shunt 61 is a potentiometer that outputs distance R;
62 is a potentiometer that outputs the cart spin angle θ, and 63 is a potentiometer that sets the cart running speed V ₀ . POT is limit switch LS
This is also a potentiometer used for calculating the above-mentioned front wall angle ±δθ. These are selected by a multiplexer 71, analog-to-digital converted by an A/D converter 72, and taken into a microprocessor MPU (not shown) via a bus 73. 64 is a motor for driving the truck 4, 66 and 65
is a pulse generator and a speed generator connected to the motor, and the speed generator 65 is used for closed loop speed control of the travel motor 64. Command speed is MPU
from the D/A converter 7 through the bus 73.
4, the signal is converted from digital to analog and input to the motor 64, specifically its control device. The output pulses of the pulse generator 66 are supplied to the linear bus 73, and are used for detecting the traveling distance of the bogie, the speed of the bogie, and the like. 6
7 is a torch moving motor, 68 is a potentiometer that detects the amount of movement (torch forward and backward movement amount);
When the above-mentioned correction amount Δl is sent from the MPU through the bus 73, it is D/A converted by the converter 69 and then used as the operating reference value, and together with the feedback amount from the potentiometer 68, the torch tip position is adjusted accurately by the amount Δl. Fix it. 51 and 52 are welding torch swinging ends P ₁ ,
P ₂ sensor. 70 is the operation pendant,
The operator gives various commands using this. Control of the cart spin and correction of the torch aiming position are performed as described above in response to the outputs of the respective potentiometers.

Effects of the Invention As explained above, according to the present invention, a profile welding device that continuously performs horizontal fillet welding by spinning a cart at a corner can be used to continuously perform horizontal fillet welding even when the side wall portion and front wall portion are tilted. Even if the angle formed by the front wall deviates from 90°, the spin and torch aiming position can be accurately corrected to perform highly accurate fillet welding, which is extremely effective.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of four continuous fillet welds using a spin-type traveling trolley, Figure 2 is an explanatory diagram of the side wall tracing section,
Figures 3 and 4 are explanatory diagrams of torch oscillation, and Figure 5
The figures are side views of the torch swing mechanism, Figures 6 and 7.
The figure is a welding current waveform diagram in the case of Figures 3 and 4, Figure 8 is an explanatory diagram of the tilting of the vertical member, Figure 9 is a welding voltage current characteristic diagram, and Figure 10 is an explanatory diagram of the cart spin angle. FIG. 11 is an explanatory diagram of the front wall inclination angle detection mechanism, FIGS. 12 and 13 are flowcharts showing the processing procedure, and FIG. 14 is a block diagram showing the main part configuration of the processing device. In the drawing, 5 is a side wall surface copying mechanism, 10, LS is a front wall surface detection mechanism, 13, 16 to 18 are torch swing mechanisms, CNT is a control device, 4 is a self-propelled trolley, 5 is a guide arm, LS is a limit switch, POT is a potentiometer, 51 and 52 are weaving end detection mechanisms,
7 is an electromagnet for spinning the cart, and A ₅ to _{A 7} are welding current values.

Claims (1)

[Scope of Claims] 1. A side wall surface copying mechanism having a pair of rotatable and lockable guide arms protruding laterally from the front and rear sides of the bogie, a front wall surface detection mechanism, and a weaving mechanism for weaving the tip of the torch with respect to the welding line. The torch is equipped with a torch swinging mechanism and a control device, and when it detects the front wall surface while tracing the side wall surface, it changes the traveling direction and continues tracing the front wall surface as the side wall surface, and during this period it continuously traces the horizontal fillet. In a trackless self-propelled trolley for welding a box-shaped structure, the front wall surface detection mechanism includes a limit switch, a potentiometer, and an operating end of the limit switch disposed opposite to the front wall surface. The operating end of the potentiometer is arranged laterally apart, the torch swinging mechanism includes a weaving end detection mechanism, and the control device detects the operating end of the limit switch while the trolley is moving straight from the side wall surface copying mechanism. When the potentiometer hits the front wall and detects the front wall, the front wall inclination angle is calculated based on the amount of retreat of the operating end of the potentiometer that hit the front wall and retreated, and the cart is moved to a predetermined angle according to the inclination angle. The present invention is provided with a means for rotating the welding current at an angle and moving the torch forward or backward so that the fluctuation state of the welding current value at the weaving end reaches a predetermined state so that the torch follows the welding line while weaving. A trackless self-propelled cart for welding featuring the following.