JP2007237220A - Method of controlling welding robot, material welded thereby, and control program of welding robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a welding robot in which cost reduction is possible through a simplified welding process without using an end tab in welding a groove joint, and also to provide a welding method using this controller and a control program of a welding robot. <P>SOLUTION: In a welding robot system 10, in welding a workpiece W1 with the end of grooves open, the controller 40 controls the welding robot 20 for the end of the grooves in the workpiece W1 in the manner that a dam S is formed by stacking weld beads s1, s2, ... and that a dam E is formed by stacking weld beads e1, e2, ... respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for controlling a welding robot that performs end welding of a metal groove joint, a welded material welded by the welding robot, and a control program for the welding robot.

Conventionally, as a method for joining metal materials, a welding method using a welding robot has been implemented. Among the welding methods using this welding robot, for example, as disclosed in Patent Documents 1 and 2, an end tab formed of steel or ceramics is attached to the weld end to perform welding. is there.
Thus, welding can be completed up to the end while preventing the weld metal from flowing out from the weld end by attaching the end tab to the weld end.
Japanese Patent No. 2904149 (registered on March 26, 1999) JP 2002-28780 A (published January 29, 2002)

However, the conventional welding robot control method has the following problems.
That is, the end tab attached to the weld end in order to prevent the welding material from flowing out from the weld end becomes an unnecessary object after welding. For this reason, in order to remove this end tab from a welding part, the operation | work which knocks off or scrapes an end tab is needed, and productivity will fall. As a result, considering that the end tab is a consumable item, the welding method using the end tab becomes a factor that increases the cost required for welding.

  An object of the present invention is to provide a welding robot control method capable of simplifying the welding process and reducing the cost by performing welding without using an end tab when welding a groove joint, and the welding It is to provide a control program for a welded material and a welding robot.

  A method for controlling a welding robot according to a first aspect of the present invention is a method for controlling a welding robot that welds a groove joint with an open end, and includes a welding method including first to third steps. To run. In the first step, a weld bead is formed at the end of the groove joint. In the second step, a weld bead is further formed on the weld bead until the weld bead is equal to or higher than a predetermined height. In the third step, welding is started inside the weld bead.

Here, in the control method of the welding robot that welds the groove joint with the open end, when welding the groove joint with the open end, the welding bead is first set before starting the welding. A weir is formed by laminating a plurality of times.
Here, the weld bead means a belt-like raised portion formed in the welded portion by melting the weld metal. Further, the weir formed by laminating the weld beads has a function of preventing the weld metal from flowing out from the end of the welded portion. Furthermore, the inner side of the weld bead means the side of the groove joint where welding is performed.

  Usually, when welding a groove joint with such an open end, a metal or ceramic end tab is attached to prevent welding metal from leaking from the open end side. Start. However, the conventional welding method using such an end tab requires a finishing process for removing the end tab from the welded portion after the welding is completed, which increases the material cost of the end tab and increases the welding process. It was a factor of up.

As described above, the welding robot control method of the present invention uses a weir formed by laminating weld beads instead of the conventional end tabs at the open end of the groove joint.
As a result, welding can be accurately performed to the end without using the end tab when welding the groove joint with the open end, and the finishing process for removing the end tab after the welding is completed. Is eliminated, and the welding process can be simplified. As a result, the cost can be reduced by omitting the material cost of the end tab and the finishing process for removing the end tab.

A welding robot control method according to a second aspect of the invention is a welding robot control method according to the first aspect of the present invention, in which a groove is opened in a groove joint using a sensor before the first step of forming a weld bead. A fourth step of detecting the previous position and width is further provided.
Here, before the weld beads are stacked to form the weir, the position of the groove portion and the width of the groove in the groove joint are detected by a sensor.

Here, as a sensor for detecting the position or the like of the groove joint, for example, the position of the groove or the like is detected by detecting a short circuit when a voltage is applied to the weld metal and the groove is brought into contact with the groove portion. A touch sensor or the like is included.
Thus, for example, even when a weld bead is stacked on the end of a groove joint having a groove at a position shifted from a groove position registered in advance in the welding robot, the actual groove position is formed. The weir can be formed while detecting the width and correcting the position of the groove registered in the welding robot. Therefore, even when the accuracy of the groove joint varies, the weir can be formed with high accuracy and the occurrence of welding defects can be avoided.

A welding robot control method according to a third invention is a welding robot control method according to the first or second invention, wherein a welding bead is formed when welding is started in the third step. Welding is started at a position spaced from the position.
Here, after welding beads are stacked on the end of the groove joint to form a weir, when starting welding, not from the above weir part formed at the end of the groove joint, but from the weir Welding is started at a spaced position.

Usually, at the beginning of welding, melting of the weld metal is unstable, and there is a problem that poor fusion between the welded material and the weld metal is likely to occur.
In the welding robot control method of the present invention, the welding robot is controlled so that welding is started from an arbitrary position inside the weir by removing the position of the weir on which the weld beads are stacked as the welding starting position. .
Thereby, it is possible to avoid the occurrence of poor fusion between the metal forming the weir and the weld metal and perform high-precision welding.

A welding robot control method according to a fourth invention is the welding robot control method according to any one of the first to third inventions, wherein the groove joint has a groove on four surfaces of the welded portion. is doing.
Here, as a groove joint for welding, a joint in which grooves are formed on four surfaces of the welded portion is used.

Usually, in the welding of a joint in which four grooves are formed in the welded portion as described above, when the end tab is used for welding, there are places where the end tab becomes an obstacle and cannot be welded.
In the method for controlling a welding robot of the present invention, a groove joint in which grooves are formed on four surfaces of a welded portion is welded using a weir in which weld beads are stacked instead of the end tab.
For this reason, it can avoid that the end tab becomes obstructive and the location which cannot be welded like the conventional welding method generate | occur | produces. As a result, it is possible to accurately weld the groove joint in which the groove is formed on the four surfaces of the welded portion.

A control method for a welding robot according to a fifth invention is a control method for a welding robot according to any one of the first to fourth inventions, wherein the formation of a weld bead and welding are performed using the same material. Do.
Here, a weld bead formed at the end of the groove portion instead of the end tab is formed using a material used for welding.
Thereby, when starting welding after forming a weld bead, the process of laminating a weld bead and the process of welding can be carried out continuously without changing the welding material. As a result, the welding process can be carried out with much higher efficiency than before.

A welding robot control program according to a sixth invention causes a computer to execute the welding robot control method according to any one of the first to fifth inventions.
Here, when controlling a welding robot that welds a groove joint with an open end, when welding a groove joint with an open end, first start the welding bead before starting welding. A computer executes a control method of a welding robot that forms a weir by laminating a plurality of times.

As a result, welding can be accurately performed to the end without using the end tab when welding the groove joint with the open end, and the finishing process for removing the end tab after the welding is completed. Is eliminated, and the welding process can be simplified.
As a result, the cost can be reduced by omitting the material cost of the end tab and the finishing process for removing the end tab.

A welded material according to a seventh aspect of the invention is welded by the welding robot control method according to any one of the first to fifth aspects of the invention.
As a result, welding can be accurately performed to the end without using the end tab when welding the groove joint with the open end, and the finishing process for removing the end tab after the welding is completed. Is eliminated, and the welding process can be simplified.

  As a result, it is possible to provide a welded material capable of reducing costs by omitting the material cost of the end tab and the finishing process for removing the end tab.

  According to the welding robot control method of the present invention, the welding process can be simplified and the cost can be reduced.

A welding robot control method, a welded material welded by the welding robot control method according to the embodiment of the present invention, and a welding robot system including a welding robot control program will be described with reference to FIGS. is there.
[Configuration of welding robot system 10 as a whole]
The welding robot system 10 according to the present embodiment welds groove joints of a workpiece (material to be welded) W1 (see FIG. 3) and a workpiece W2 (see FIG. 10 (a), etc.) having a groove portion at an end. As shown in FIG. 1, the system automatically controls the welding robot 20 and includes a welding robot 20, a positioner 30, a controller 40, and a welding power supply device 50.

  In the present embodiment, the workpiece W1 having one groove at the welded portion formed at the portion where the workpiece Wa and the workpiece Wb are joined as shown in FIG. 3, and FIGS. 10 (a) and 10 (b). A workpiece W2 having four grooves at a welded portion formed at a portion where the workpiece Wa and the workpiece Wc are joined will be described as an example of a workpiece to be welded in the welding robot system 10.

(Welding robot 20)
As shown in FIG. 1, the welding robot 20 is a device that welds a workpiece W while feeding a welding wire 22 from a welding torch portion provided at the tip of a robot arm 21, and includes a robot arm 21, a traveling beam 23, A ceiling-mounted traveling carriage 24 and a traveling platform 25 are provided.
The robot arm 21 melts the welding wire 22 while feeding the welding wire 22 from the welding torch portion provided at the tip thereof, welding the welded portion of the workpiece W, welding beads s1, s2,. A weir S or a weir E (see FIG. 3) in which the beads e1, e2,. Further, the robot arm 21 uses a welding torch to accurately grasp the welding positions of the workpieces W1 and W2 held by the holding portions 31 and 32 of the positioner 30 described later, and to form and weld the weirs S and E. A short circuit that occurs when a voltage is applied to the fed welding wire 22 to contact the groove portion is detected. Thereby, the welding wire 22 sent out from the welding torch can be used as a wire touch sensor for detecting the position, width, shape and the like of the groove portion.

The traveling beam 23 is a beam member extending in a direction substantially perpendicular to the longitudinal direction of the positioner 30. The welding robot 20 moves along the traveling beam 23 and moves in a direction substantially perpendicular to the positioner 30.
The ceiling suspension traveling carriage 24 moves along the traveling base 25 parallel to the longitudinal direction of the positioner 30, thereby moving the welding robot 20 to an arbitrary position with respect to the workpieces W <b> 1 and W <b> 2 held by the positioner 30.

(Positioner 30)
As shown in FIG. 1, the positioner 30 is disposed in front of the welding robot 20 and holds the workpiece W between the pair of holding portions 31 and 32. The positioner 30 moves the workpieces W1 and W2 held between the holding units 31 and 32 to arbitrary positions by moving the holding units 31 and 32 in the longitudinal direction, and rotates the holding units 31 and 32. By doing so, the direction of the workpieces W1, W2 can be changed.

Thereby, the groove part of the workpiece | work W hold | maintained in the positioner 30 can be moved to the position which can be welded within the movement range of the welding robot 20. FIG.
(Controller 40)
As shown in FIG. 2, the controller 40 is connected to the welding robot 20, the positioner 30, and the welding power supply device 50. The controller 40 controls driving of the drivable members 21 and 24 included in the welding robot 20 and the holding portions 31 and 32 of the positioner 30.

  The controller 40 stores groove position data and groove width data corresponding to the workpieces W1 and W2 in the internal storage unit 40a. The welding robot 20 grasps the position and shape of the groove based on the groove position data and groove width data stored in the storage unit 40a. And when laminating weld beads e1, e2,... Etc. to form the weir E etc., after correcting the groove position to be described later, the position and shape of the groove are accurately recognized. The weir E can be formed with high accuracy.

(Welding power supply 50)
The welding power supply device 50 feeds the welding wire 22 placed on the traveling platform 25 included in the welding robot 20, and performs arc welding by flowing a high current.
<Control of welding robot in welding robot system 10>
In the welding robot system 10 of the present embodiment, as described above, the workpiece W1 shown in FIG. 3 and the workpiece W2 shown in FIG. 10A are welded while controlling the operation of the welding robot 20 by the controller 40.

(Welding of workpiece W1 with one groove)
As shown in FIG. 3, the workpiece W1 is a workpiece to be welded obtained by joining the ends of the workpieces Wa and Wb, which are two plate members, and a groove on one surface is formed at the end on the workpiece Wb side. Has been. And when welding this workpiece | work W1, the controller 40 is welded so that the weirs S and E may be formed by laminating the weld beads s1 to s4 and e1 to e4 on both ends of the welded portion of the workpiece W1, respectively. The robot 20 is controlled.

Specifically, first, the workpieces Wa and Wb temporarily fixed with the backing material Z in a state where the welded portions of the workpieces Wa and Wb are opposed to each other between the holding portions 31 and 32 of the positioner 30. Hold.
Thereafter, correction of the reference point for accurately detecting the position and shape of the groove portion forming the weirs S and E, which is performed before forming the weirs S and E, is shown in FIGS. It will be as follows if it demonstrates using the side view of 4 (b), and the flowchart shown in FIG.

  That is, in step S1, four points P1, P2, P3, and P4 that form groove portions stored in the storage unit 40a of the controller 40, a groove width w at a height h, and an intermediate position P0 (FIG. 4). In order to accurately detect the actual groove position, shape, etc., as shown in FIG. 4A, a welding wire 22 fed from the welding torch of the robot arm 21 is used as shown in FIG. The groove center position P0 ′ and the groove width w ′ of the groove portion to be actually welded are detected by the wire touch sensor. More specifically, the controller 40 moves the robot arm 21 downward until the tip of the welding wire 22 contacts the bottom surface of the groove portion, and raises the robot arm 21 by a height h therefrom. Thereafter, the robot arm 21 is reciprocated in the groove width w direction while maintaining the position of the height h, and the welding wire 22 and groove portions (wall surfaces P1 ′, P3 ′ and wall surface P2 ′ in the width direction). , P4 ′) is detected. Then, based on the detected contact positions on both sides in the width direction, a groove center position P0 'that is an intermediate point is detected.

Next, in step S2, the controller 40 reads the groove center position P0 and the groove width w stored in advance in the storage unit 40a.
In step S3, a correction vector Vs for correcting the groove center position to the actual position connecting the groove center positions P0 and P0 ′ is calculated.
In step S4, the groove width correction amount dW is calculated based on the following relational expression (1).

dW = (w′−w) / 2 (1)
In step S5, a correction unit vector Vk1 in the groove width direction of points P1 and P2 is calculated. The correction unit vector Vk1 is calculated by dividing the vector connecting the points P1 and P2 by the length.
In step S6, based on the correction vector Vs, the groove width correction amount dW, and the correction unit vector Vk1, the points P1, P2 stored in the storage unit 40a according to the following relational expressions (2), (3): The points P1 ′ and P2 ′ corrected by the above are calculated.

P1 ′ = P1 + Vs−dw · Vk1 (2)
P2 ′ = P2 + Vs + dw · Vk1 (3)
In step S7, as in step S5, a correction unit vector Vk2 in the groove width direction of points P3 and P4 is calculated. This correction unit vector Vk2 is calculated by dividing a vector connecting points P3 and P4 by its length.

In step S8, as in step S6, based on the correction vector Vs, the groove width correction amount dW, and the correction unit vector Vk2, the following relational expressions (4) and (5) are stored in the storage unit 40a. Points P3 ′ and P4 ′ obtained by correcting the obtained points P3 and P4 are calculated.
P3 ′ = P3 + Vs−dw · Vk2 (4)
P4 ′ = P4 + Vs + dw · Vk2 (5)
Here, in steps S1 to S8 as described above, the points P1 to P4 which are the reference points of the grooves are corrected according to the actual groove positions to obtain corrected points P1 ′ to P4 ′. .

  Furthermore, in the welding robot system 10 of the present embodiment, after correcting the reference point described above, the molten welding wire 22 or the like does not flow out from both end portions of the groove where the welded wire 22 or the like is opened at both ends of the welded portion of the workpiece W1. The weirs S and E for doing so are formed. Here, the formation of the weirs S and E will be described as follows with reference to the side view of FIG. 4C and the flowchart shown in FIG.

That is, in step S11, a vector V0 that connects the midpoint of the corrected points P1 ′ and P2 ′ and the midpoint of the points P3 ′ and P4 ′ is calculated. The vector V0 is calculated by adding a vector connecting the points P1 ′ and P3 ′ and a vector connecting the points P2 ′ and P4 ′ and dividing by two.
In step S12, vectors connecting point P3 ′ and point P1 ′ and vectors obtained by dividing point P4 ′ and point P2 ′ by the length of V0 are calculated as V1 and V2.

In step S13, as shown in FIG. 4C, the height d from the groove bottom is set to 0 in order to sequentially stack the weld beads e1, s1 from the groove bottom.
In step S14, welding positions Q0, Q1, and Q2 are calculated based on the following relational expressions (6), (7), and (8).
Q1 = P1 ′ + d · V1 (6)
Q2 = P2 ′ + d · V2 (7)
Q0 = (Q1 + Q2) / 2 (8)
In step S15, the controller 40 performs welding by the welding robot 20 in the order of the point Q1, the point Q2, and the point Q0 from the center point Q0 of the both end points Q1 and Q2 in the groove width direction.

In step S16, it is determined whether or not the height d is larger than the absolute value of V0. If the height d is smaller than V0, the process proceeds to step S17. On the other hand, when the height d exceeds the absolute value of V0, it means that the weirs S and E having a height high enough to cover the end of the groove are formed. The process of forming is terminated.
In step S17, d is accumulated by one layer ΔD (the thickness of the weld bead), and the processes from step S14 to step S17 are repeated.

  Finally, in the welding robot system 10 according to the present embodiment, the weirs S and E are formed after forming the weirs S and E at both ends of the opened groove through the processing from step S11 to step S17 described above. Weld the groove part between. Here, the welding between the weirs S and E will be described with reference to the side view of FIGS. 7A and 7B, the flowchart shown in FIG. 8, and the plan view shown in FIG. is there.

The welding operation between the weirs S and E is performed using the same welding wire 22 as that for forming the weirs S and E.
That is, in step S21, the number of welding passes is set to 1, and the height d from the groove bottom is set to 0.
In step S22, as shown in FIG. 7A, with reference to the corrected groove reference points Ps1 ′ to Ps4 ′, the welding positions Qs0, Qs1, Qs2 at the height d of the weir S and FIG. ), The welding positions Qe0, Qe1, and Qe2 at the height d of the weir E are calculated on the basis of the corrected groove reference points Pe1 ′ to Pe4 ′.

In step S23, on the line connecting the welding position Qs0 and the welding position Qe0, a position Qs3 that is inside by a distance L from the welding position Qs0 and a position Qe3 that is inside by a distance L from Qe0 are calculated (see FIG. 9). The inner side from the welding positions Qs0 and Qe0 means the inner side of the welded portion sandwiched between the weirs S and E as shown in FIG.
In step S24, as shown in FIG. 9, welding is started from position Qs3, and welding in the vicinity of weir S is performed in the order of Qs1, Qs2, and Qs3.

In step S25, as shown in FIG. 9, welding is performed between the weirs S and E while the welding robot 20 is weaved from the position Qs3 to the opposite position Qe3.
In step S26, welding is performed by welding robot 20 in the order of positions Qe3 to Qe1, Qe2, and Qe3, and the crater is terminated.
In step S27, it is determined whether or not the number of welding passes has reached a predetermined number. Here, when the number of welding passes has reached the designated number of passes, the processing is terminated. On the other hand, if the number of welding passes has not reached the specified number of passes, the process proceeds to step S28.

In step S28, the number of welding passes is set to +1, the height d is accumulated by one layer ΔD, and the processing from step S22 to step S28 is repeated again.
In the welding robot system 10 of the present embodiment, as described above, when welding the workpiece W1 having a groove portion with both ends released, first, the weld beads s1, .. are stacked a plurality of times to form a weir E by stacking the weir S and the weld beads e1, e2,. And after formation of the weirs S and E, the welding part between them is welded.

  Accordingly, the welded material (the welding wire 22 and the melted portion of the workpiece W1) leaks from the open portion without using an end tab which has been conventionally used when welding a groove having open portions at both ends. Can be prevented, and high-precision welding can be performed. Furthermore, since the welding is performed without using the end tab, a process for removing the end tab from the welded portion after the welding becomes unnecessary, and the efficiency of the welding process can be improved.

And when forming the weirs S and E, formation of the weirs S and E is started after detecting the position and width of an actual groove part using a wire touch sensor.
Thereby, even when the position and shape of the groove vary for each workpiece W1, the weirs S and E can be formed after accurately recognizing the position of the groove.
Furthermore, by performing the formation of the weirs S and E and the welding operation between the weirs S and E using the same welding wire 22, the work W1 can be more efficiently welded.

(Welding of workpiece W2 with 4 groove)
As shown in FIGS. 10A and 10B, the workpiece W2 is a workpiece to be welded obtained by joining the ends of the workpieces Wa and Wc, which are two plate members, and is provided on the workpiece Wc side. A four-sided groove is formed at the end. When welding the workpiece W2, the controller 40 stacks the weld beads s1 to s4 and e1 to e4 on both ends of the welded portion of the workpiece W2, respectively, and sets the weirs S1, S2 and the weirs E1, E2. The welding robot 20 is controlled to form.

The correction of the reference position for forming the weir, the formation of the weir, and the welding work between the weirs for the workpiece W2 are basically the same as the processing for the workpiece W1 described above. For this reason, the process part different from the process with respect to the workpiece | work W1 mentioned above is demonstrated here.
Specifically, as shown in FIG. 11, first, the workpiece W <b> 2 (work Wa and workpiece Wc) is held by the positioner 30 in accordance with the welding position by the welding robot 20. And the direction of the workpiece | work W2 is changed by rotating the positioner 30, and the weirs S1, S2 and the weirs E1, E2 are formed.

At this time, since the groove is formed on the four surfaces of the welded portion in the workpiece W2, in order to form an effective weir for the leakage of the molten material at the end of the opened welded portion, As shown in FIGS. 12 (a) to 12 (d), it is necessary to form weirs S1, S2 and weirs E1, E2 between the groove portions.
For this reason, when welding the workpiece W2, as shown in FIG. 11, the angle of the workpiece W2 by the positioner 30 with respect to the welding position using the welding wire 22 fed from the tip of the robot arm 21 of the welding robot 20. 12 (a) to 12 (d), the weld beads are stacked to form four weirs S1, while being inclined at an angle of 45 degrees between the two groove surfaces, as shown in FIGS. S2, E1, and E2 are formed one by one. In addition, about the formation method of each weir S1, S2, E1, and E2 here, it is the same as the formation method shown in FIG.4 (c) mentioned above.

After forming the weirs S1, S2, E1, and E2, as shown in FIGS. 13 (a) to 13 (d), the robot arm 21 of the welding robot 20 is moved to perform welding between the weirs. Weld the parts. In addition, about the welding method between each weir here, it is the same as that of the welding method shown in FIG. 9 etc. which were mentioned above.
Thereby, even when welding the workpiece | work W2 which has four groove | channels in a welding part, welding work can be implemented, without using the conventional end tab. As a result, an operation for removing the end tab after the welding operation is completed becomes unnecessary, so that highly accurate welding can be performed while improving the workability of the welding operation.

[Features of Control Method of Welding Robot 20 in Welding Robot System 10]
(1)
In the welding robot system 10 of the present embodiment, when welding the workpiece W1 with the end portion of the groove portion opened, the controller 40 is connected to the end portion of the groove portion in the workpiece W1 with reference to FIG. As shown in FIGS. 4A to 4C, the weld beads s1, s2,... Are stacked to form the weir S, and the weld beads e1, e2,. The welding robot 20 is controlled to form each.

  Thereby, without attaching the end tab attached to the open end in the welding method using the conventional welding robot to the open end side in the groove portion of the workpiece, while preventing leakage of the molten welding material, Welding can be performed. As a result, since the operation for removing the end tab from the welded portion is not required after the welding is completed, the efficiency of the welding operation can be greatly improved as compared with the conventional case. Furthermore, by not using the end tab, the cost of the end tab, which is a consumable item, can be reduced and the cost can be reduced.

(2)
In the welding robot system 10 of the present embodiment, when the weirs S and E are formed in order to prevent the welding material from leaking out from the open tip portion described above, FIGS. 4A and 4B are used. As shown, a controller is used to detect the actual groove position, groove width, etc., using a wire touch sensor that applies a voltage to the welding wire 22 fed from the tip of the robot arm 21 of the welding robot 20. 40 controls the welding robot 20.

  As a result, even when there is a deviation between the groove position and the like registered in advance in the storage unit 40a and the actual groove positions of the workpieces W1 and W2, information such as the groove position is accurately acquired by the wire touch sensor. Then, formation of the weirs S and E and welding work between the weirs S and E can be performed. As a result, even when the positions and shapes of the grooves of the workpieces W1 and W2 vary, the weirs S and E are formed with high accuracy and the welding operation is performed, thereby preventing the occurrence of poor welding and the product yield. Can be improved.

(3)
In the welding robot system 10 of the present embodiment, as described above, when the welding operation is started after the weirs S and E are formed at the open end of the groove, as shown in FIG. The controller 40 controls the welding robot 20 so as to start welding at a position separated from the formation position of, and finish the welding operation at a position separated from the weirs S and E.

Normally, at the start of welding and at the end of welding, the molten state of the welding wire sent out from the welding torch at the tip of the robot arm becomes unstable, and there is a possibility that welding failure may occur.
For this reason, in this embodiment, the welding start position and the welding end position at which this melting tends to become unstable are set at positions separated from the weirs S and E formed in the pre-welding stage.
Thereby, compared with the case where welding is started from the vicinity of the weirs S and E, it is possible to effectively prevent the occurrence of welding defects due to poor melting in the portions of the weirs S and E.

(4)
In the welding robot system 10 of the present embodiment, as shown in FIGS. 10A and 10B, the controller 40 performs welding so as to weld the workpiece W2 having grooves formed on the four surfaces of the welded portion. The robot 20 is controlled.
Here, in the welding method using the conventional end tab, when welding the workpiece | work with which the groove | channel was formed in the four surfaces of a welding part, an end tab will become obstructive and the location which cannot be welded will generate | occur | produce.

  In contrast, in the present embodiment, as shown in FIGS. 11 and 12A to 12D, one weir S1, S2, E1, and E2 is provided while the workpiece W2 is rotated by the positioner 30. Since they are formed one by one, it is possible to weld all four groove portions between the weirs S1, S2, E1, and E2. As a result, it is particularly effective to apply the control method of the welding robot 20 according to the present embodiment to the welding of the workpiece W2 having grooves on the four surfaces of the welded portion shown in FIG.

(5)
In the welding robot system 10 of the present embodiment, the formation of the weirs S and E and the welding operation between the weirs S and E are performed using the same welding wire 22.
As a result, even when welding between the weirs S and E is performed, there is no need to change the welding material, and the welding operation can be immediately performed. As a result, it is possible to carry out the welding work more efficiently and accurately.

(6)
Workpieces (materials to be welded) W1 and W2 by the welding robot system 10 of the present embodiment are welded by the above-described method of controlling the welding robot 20 by the welding robot system 10.
Thus, as described above, the work efficiency is improved compared with the conventional welding method using the end tab, and the cost of the end tab is reduced, and the workpiece W1, which is welded with high accuracy at low cost, is reduced. W2 can be obtained.

[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.
(A)
In the above embodiment, as shown in FIG. 4A and the like, the position of the groove portion is determined using a wire touch sensor that applies a voltage to the welding wire 22 fed from the distal end portion of the robot arm 21 of the welding robot 20. After detecting the shape and the like, an example in which the weld beads s1, s2,... Or the weld beads e1, e2,. However, the present invention is not limited to this.

For example, when the groove joint is precisely formed, it seems that there is no variation in the position, shape, etc. of the groove portion. First, a predetermined position, etc. is input to the control unit side of the welding robot. In this case, it is not necessary to detect the groove position or the like every time before the welding beads are stacked and the weir is formed as in the above embodiment.
However, considering the fact that the yield of the product is reduced when forming the groove joint with high accuracy, after detecting the position of the groove portion for each groove joint as in the above embodiment, More preferably, the welding beads are stacked.

(B)
In the above embodiment, the weld beads s1, s2,... And the weld beads e1, e2,. In the above description, the welding is started from the inside by the distance L between the formation portions of the weirs S and E, and the welding is finished at the inside by the distance L between the formation portions of the weirs S and E. However, the present invention is not limited to this.

The position where the welding is started and ended is not limited to a little inside of the weirs S and E. For example, the welding may be started and ended at a central portion between the weirs and the weirs.
However, when welding is started from the central portion between the weir S and the weir E, the efficiency of the welding process may be reduced. Therefore, as in the above embodiment, the weirs S and E are slightly inside. More preferably, welding is started from the beginning.

(C)
In the above embodiment, as shown in FIG. 4A and the like, a welding wire sent out from the tip portion of the robot arm 21 of the welding robot 20 as a sensor for detecting the position and groove width of the groove portion of the groove joint. An example using a wire touch sensor that detects a contact position with a groove portion by applying a voltage to 22 and detecting a short circuit due to contact with the groove portion has been described. However, the present invention is not limited to this.

For example, other sensors such as a non-contact type sensor including an infrared sensor can be used as a sensor for detecting the position and shape of the groove portion.
However, it is more preferable to use a welding wire as a sensor as in the above embodiment in that the position of the groove portion and the like can be detected without increasing the number of components such as an infrared sensor.

(D)
In the above embodiment, the welding beads s1, s2, ... or the welding beads e1, e2, ... are stacked to form the weirs S, E, and the welding process of welding the weirs S, E. An example in which processing is performed using the same welding material (welding wire 22) has been described. However, the present invention is not limited to this.

For example, different materials may be used in the welding bead laminating process and the welding process.
Even in this case, it is possible to obtain the same effect as described above that the groove joint can be efficiently welded without using an end tab.
However, when the above two steps are performed with different materials, work such as material replacement work is required at the start of welding, and work efficiency is reduced. More preferably, the same material is used as in the embodiment.

(E)
In the said embodiment, as shown in FIG.3, FIG.10 (a) and FIG.10 (b), the workpiece | work W1 in which the groove | channel was formed in 1 surface in the edge part of a groove joint, or groove | channel on 4 surfaces. An example using the workpiece W2 formed with the above has been described. However, the present invention is not limited to this.

For example, it is naturally possible to apply the present invention to welding of a material to be welded in which a groove is formed on only two surfaces or three surfaces at the end of the groove joint.
However, in the conventional welding method using the end tab, when welding a material to be welded having four grooves formed on the four surfaces, a portion that cannot be welded occurs because the end tab becomes an obstacle. For this reason, it is particularly effective in comparison with the conventional welding method to apply the present invention to welding of a groove joint having grooves formed on four surfaces as in the above embodiment.

(F)
In the said embodiment, when welding the workpiece | work W2 which has four groove | channels in a welding part, the example which forms the weirs S and E in the substantially perpendicular direction in the state which inclined the workpiece | work W2 45 degree | times is given. explained. However, the present invention is not limited to this.
For example, the weirs S and E may be formed at the open ends of the workpieces W2 without tilting the workpieces with the grooves held substantially horizontally.

However, for the workpiece W2 having grooves on four sides, the number of necessary weirs S and E may be set to a minimum of four by forming a weir at 45 degrees with respect to each groove as described above. It is more preferable to form a weir as in the above-described embodiment.
(G)
In the said embodiment, the example which welds with respect to the workpiece | work W1, W2 from which the both ends of groove | channel were open | released was given and demonstrated. However, the present invention is not limited to this.

For example, it is possible to perform welding by applying the present invention to a workpiece in which only one end of the groove is opened.
Even in this case, it is possible to perform a highly accurate welding operation while preventing the molten material from leaking from the open end portion.
(H)
In the said embodiment, the example which applied this invention with respect to the welding robot system 10 which performs the control method of a welding robot was given and demonstrated. However, the present invention is not limited to this.

  For example, the present invention can also be applied to a welding robot control program that causes a computer to execute the welding robot control method described in the above embodiment.

  Since the welding robot control method of the present invention performs welding without using an end tab when welding a groove joint, the welding process can be simplified and the cost can be reduced. It can be widely applied to various welding apparatuses and welding robots for welding groove joints.

1 is a perspective view showing a schematic configuration of an entire welding robot system according to an embodiment of the present invention. The control block diagram formed in the welding robot system of FIG. The perspective view which shows an example of the to-be-welded object welded in the welding robot system of FIG. (A)-(c) is sectional drawing which shows the motion of the welding robot at the time of detecting the position, shape, etc. of the groove | channel in the to-be-welded object of FIG. 4, and laminating | stacking a weld bead. The flowchart which shows the flow of a process at the time of correct | amending the welding position etc. by the welding robot system of FIG. The flowchart which shows the flow of a process at the time of forming a dam in the edge part of the groove part by the welding robot system of FIG. (A) And (b) is sectional drawing which shows a motion of the welding robot at the time of welding between the dams formed in the to-be-welded object of FIG. The flowchart which shows the flow of a process at the time of welding between the weirs by the welding robot system of FIG. FIG. 5 is a plan view showing a rod carrying method when welding the workpiece of FIG. 4. (A) And (b) is the side view and top view which show the other example of the to-be-welded object welded in the welding robot system of FIG. The perspective view which shows the positional relationship of the welding robot at the time of welding the to-be-welded object shown to Fig.10 (a) and FIG.10 (b), and a to-be-welded object. (A)-(d) is a side view which shows the flow at the time of forming a weir with respect to the to-be-welded object shown to Fig.10 (a) and FIG.10 (b). (A)-(d) is a side view which shows the flow at the time of welding between a dam with respect to the to-be-welded object shown to Fig.10 (a) and FIG.10 (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Welding robot system 20 Welding robot 21 Robot arm 22 Welding wire (welding material)
23 traveling beam 24 ceiling suspended traveling vehicle 25 traveling platform 30 positioner 31, 32 holder 40 controller 50 welding power source device e, s welding bead E, S weir W work (material to be welded)
Z backing material

Claims (7)

A method for controlling a welding robot for welding a groove joint whose end is opened,
A first step of forming a weld bead at an end of the groove joint;
A second step of further forming a weld bead on the weld bead until the weld bead is greater than or equal to a predetermined height;
A third step of starting welding inside the weld bead;
A welding robot control method for causing a welding robot to execute a welding method including: Before the first step of forming the weld bead, further comprising a fourth step of detecting the position and width of the groove in the groove joint using a sensor;
The method for controlling a welding robot according to claim 1. When starting welding in the third step, welding is started at a position spaced from the position where the weld bead is formed.
The method for controlling a welding robot according to claim 1 or 2. The groove joint has a groove on four sides of the welded portion,
The control method of the welding robot of any one of Claim 1 to 3. The welding bead formation and the welding are performed using the same material.
The control method of the welding robot of any one of Claim 1 to 4. The control method of the welding robot according to any one of claims 1 to 5,
A welding robot control program to be executed by a computer.   A welded material welded by the welding robot control method according to claim 1.

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