JPH0428695Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a welding robot for weaving welding first and second objects to be welded along a predetermined welding line.

(Conventional technology and its problems) One of the important functions of welding robots is weaving welding. This weaving welding
Predetermined weaving pattern as shown in the figure
This is a welding method in which the welding torch T is moved along the welding line WL while swinging in a direction substantially perpendicular to the welding line WL according to PT (the bold line portion shown is one pattern). Conventionally, when such weaving welding is performed using a welding robot, the weaving amplitude A and pitch P are generally set as constant values in a computer in advance, as shown in FIG. Weaving welding is automatically performed while the tip of the torch T is oscillated according to a weaving pattern determined from a constant weaving amplitude A and pitch P. The welding speed V is the welding line WL
The speed at which the torch T travels in the direction is set in advance in the computer, and when performing weaving welding, the oscillation period (1
The torch T is oscillated at the pattern oscillation time.

However, the workpieces to be welded (referred to as "objects to be welded" in this specification) are two workpieces to be welded together.
The two objects to be welded are respectively expressed as "first" and "second." ), due to variations in cutting accuracy, bending accuracy, assembly accuracy due to bending and distortion of the material, and their accumulated errors, the butt interval and groove width between the first and second workpieces (in this specification) In this book, these are collectively referred to as the "mutual spacing" of the objects to be welded.) are often non-uniform in the weld line direction. Even if such welding objects are weaved by a welding robot using the above-mentioned conventional method, welding is performed with a constant weaving amplitude that ignores non-uniformity of mutual spacing, and welding may occur depending on the location. Over or under welding occurs, resulting in a significant deterioration in welding quality.

In order to solve this problem, the applicant of the present application previously proposed automatic weaving welding with variable amplitude in Japanese Patent Application No. 13292/1983. Weaving welding is performed by the welding robot while the amplitude is automatically changed depending on the non-uniformity of the mutual spacing of the objects to be welded. However, in this case, the welding speed V is preset in the computer as the advancing speed of the torch T in the direction of the welding line WL, as described above, and the advantage is that welding is performed at the desired speed in the direction of the welding line. However, the traveling speed V' of the torch T in the weaving direction changes depending on the weaving amplitude. In other words, the speed in the weaving direction when the amplitude is small
V ₁ ' is relatively small, and when the amplitude is large, the velocity in the weaving direction V ₂ ' becomes relatively large. As a result, the amount of welded metal becomes slightly non-uniform depending on the weaving amplitude, resulting in a problem in that high quality welding accuracy is somewhat hindered.

(Purpose of the invention) The purpose of this invention is to provide a welding robot that can solve the above problems and further improve welding accuracy by making the amount of deposited metal uniform when performing variable amplitude weaving welding. be.

(Means for achieving the object) In order to achieve the above object, this invention provides a welding robot for weaving welding the first and second objects to be welded along a predetermined welding line.
When performing weaving welding while changing the weaving amplitude in accordance with a change in the mutual spacing between the first and second objects to be welded, the advancing speed of the welding torch in the weaving direction is controlled so as to be always constant. I have to.

(Function) Even when weaving welding by changing the weaving amplitude according to changes in the mutual spacing between the first and second objects to be welded, the speed of progress in the weaving direction is always controlled to be constant. , the amount of metal deposited by the welding torch can be uniform.

(Example) Figure 1 shows an X, Y, Z orthogonal coordinate system welding robot used as the welding robot that forms the background of this invention.
It is an overall schematic diagram of RO.

A vertical shaft 1 formed at the end of this welding robot RO (details not shown) supports a first arm 2 so as to be pivotable around the shaft 1 (in the direction of arrow α). Further, a second arm 3 is provided at the tip of the first arm 2 and is supported so as to be pivotable around an oblique shaft 3a (in the direction of arrow β). A welding torch 4 (an MIG welding torch in this embodiment) as an end effector is attached to the tip of the second arm 3.

The shafts 1, 3a, and central axes M of the torch 4 are configured to intersect at one point P. Furthermore, the torch 4 is set so that its welding operating point can coincide with the point P. In such a configuration, by controlling the rotation angle in the directions of the arrows α and β, the attitude angle θ and the turning angle ψ (so-called Euler angle) of the torch 4 with respect to the vertical axis 1 can be controlled by fixing the point P. It's summery.

Device 5 is a welding power supply device. This power supply device 5
The spool 6 is equipped with a spool 6 on which the consumable electrode 4a of the torch 4 is wound up, and the electrode 4a can be drawn out by rotating a feed roller, although details are not shown.

A computer 7, known as a control device for this entire embodiment, includes a CPU and a memory.
A power supply device 5 is connected to the bus line B of the computer 7. Bus line B also has
The X-axis servo system SX of the robot RO is connected, and this servo system SX includes the X-axis power MX and an encoder EX that outputs its position information. Similarly, the bus line B has a Y-axis servo system SY, a Z-axis servo system SZ, and
An α-axis servo system Sα and a β-axis servo system Sβ are connected.

The remote control panel 8 has a numeric keypad TK for data input.
In addition, a group of switches (not shown) (for example, a switch for manual operation of the torch 4, a switch for speed command,
It consists of switches for setting various welding conditions, a start switch, etc.).

On the other hand, the workpiece WK in this example is the first
As shown in the figure, each of two horizontal plates W1 and W2 as the first and second objects to be welded has a groove B.
It is assumed that horizontal plates W1 and W2 are butted and welded together. However, as shown in the figure, the spacing between the butts is uneven for some reason.
It is assumed that although they are in contact with each other at the lower end in the figure, they are slightly open toward the top (far away).

Next, the operation of the embodiment of this invention will be explained, focusing on the parts related to this invention. The operator's first task is teaching, and the teaching points can be, for example, eight points P ₁ to _{P 8} shown in FIG. P ₁ and P ₈ are the retraction points, P ₂ is the welding start point, and P ₇ is the welding end point. In addition, P ₃ and P ₄ are pattern points (P ₂ , P ₂ , and P ₄ teach one weaving pattern), and P ₅ and P ₆ are dummy points (P ₃ to _P6
The change in groove width is defined by the four points. The operator uses the remote control panel 8 to sequentially position the torch 4 at each of the above points P ₁ to _{P 8} in manual mode, and operates each predetermined data acquisition switch to teach the computer 7 the position information of each point. . At this time, welding conditions such as welding current, welding voltage, and welding speed, as well as all other necessary information, are taught. The welding conditions may be set in advance as a menu depending on the type of workpiece and selected using the numeric keypad TK, or may be individually entered using the numeric keypad TK. In any case, before actual welding, determine the optimal welding speed V _c for the workpiece.
is set. This welding speed V _c defines the speed at which the torch 4 moves in the weaving direction.

When the teaching is completed and the operator turns on the start switch on the remote control panel 8, the welding port RO executes actual weaving welding under the control of the computer 7. Figures 2 and 3
The dotted line in the figure shows the trajectory F of the tip of the torch 4 during actual weaving welding. The torch 4 moves from point P ₁ to P ₂ by direct interpolation, and from point P ₂
Starting from welding, the section from points P ₃ and P ₄ to point P ₇ is weaved while changing the weaving amplitude. At this time, the advancing speed of the torch 4 in the weaving direction is always maintained at the preset optimal speed V _c regardless of changes in the weaving amplitude, and as a result, the amount of welded metal remains constant regardless of changes in the groove width. As a result, high quality weaving welding is achieved. When welding is completed at point P ₇ , the torch 4 moves to point P ₈ by linear interpolation, thereby completing a series of welding processes.

In addition, in the above embodiment, variable amplitude weaving was explained in the case where the mutual spacing was non-uniform as it linearly widened as it progressed, but this invention is applicable to any kind of mutual spacing with variable amplitude weaving It can also be applied to cases of non-uniformity. Furthermore, the method of teaching the non-uniformity is arbitrary, and does not necessarily have to be carried out by setting the specific position of the torch 4 as described above. You can also select and input using the menu method. This invention is not affected by such differences in teaching methods.

(Effect of the invention) As described above, the welding robot according to the invention is controlled so that the advancing speed of the welding torch in the weaving direction is always kept constant even if the weaving amplitude changes. If this advancing speed is set in advance to an optimal value according to the type of workpiece, welding will be performed while the optimal speed is always maintained, and the required amount of weld metal will be distributed over the entire welding surface. It can be formed uniformly, resulting in excellent welding accuracy.

[Brief explanation of drawings]

Figure 1 is an overall view of the welding robot that is the background of this invention, Figures 2 and 3 are explanatory diagrams showing the teaching point and torch trajectory in an embodiment of this invention, and Figures 4 to 6 are weaving welding. FIG. RO...Welding robot, 4...Torch, 8...
Remote control panel, WL...Welding line, W1, W2...Horizontal plate material.

Claims (1)

[Scope of utility model registration request] A welding robot for weaving welding a first and a second workpiece along a predetermined welding line, the welding robot changing the weaving amplitude according to a change in the mutual spacing between the first and second workpieces. A welding robot characterized in that when performing weaving welding, the advancing speed of a welding torch in the weaving direction is controlled to always be constant.