JPH07102462B2 - Multi-layer welding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multi-layer welding method using a welding robot.

[Conventional technology]

Instead of conventional welding work that relies on the experience and intuition of workers,
Welding robots have been popularized for the purpose of saving labor, improving quality, and improving environmental conditions such as welding work. Among welding operations performed by a welding robot, multi-layer welding is a very important operation for securing the strength of the welded portion, but it is technically difficult in many cases.

In Japanese Patent Laid-Open No. 187270/1983, the movement locus of the first layer is stored, the shift width ΔS is given as a parameter, and the shift directions of the second and subsequent layers are obtained from the stored data of the first layer. A method of performing multi-layer welding by obtaining the motion loci of the second and subsequent layers from the shift width is described.

However, this method is teaching on the XY plane, and is a method within the constraint of setting the shift amount in an arc shape and only in one direction.

However, in practice, it is difficult to define the welding locus on the XY plane, and the shift direction of the multi-layer welding must be considered three-dimensionally instead of two-dimensionally.

For this reason, it is impossible to perform multi-pass welding by the above method.

Further, JP-A-57-50279 discloses a welding robot capable of calculating a welding torch tip position from predetermined constants and variables and controlling the welding torch tip to follow a desired trajectory. Sequentially change the preset amount,
There is described a welding robot capable of performing multi-layer welding by moving the tip of the welding torch from a desired locus by the preset amount.

[Problems to be Solved by the Invention]

However, in this welding robot, since the position control is performed by obtaining the angles of the two axes of the wrist from the scaling shift amount, the robot mechanism is limited and is not general-purpose. Further, since the wrist is composed of two axes, there is a problem that the degree of freedom of the torch posture, which is indispensable for welding, is poor (at least three degrees of freedom are required for the wrist to increase the degree of freedom).

The present invention has been made in view of such conventional problems, and an object of the present invention is to automatically perform multi-layer welding automatically by only setting a simple shift amount after the second layer by an operator. To do.

[Means for Solving the Problems]

In order to achieve this object, the multi-layer welding method of the present invention,
When teaching the first layer, teach the reference point and set the horizontal shift amount and vertical shift amount of each layer as parameters. From the teaching start point, end point, and reference point, the scaling shift direction is horizontal and vertical. Is obtained, the operation locus of the second and subsequent layers is calculated from the scaling shift direction and the shift amount, and multi-layer welding is performed.

[Action]

In the present invention, the motion loci of the second and subsequent layers are calculated based on the teaching points and the reference points of the first layer. FIG. 1 is an explanatory diagram showing a method of obtaining an offset direction and an offset amount, which are the basis for obtaining the motion loci of the second and subsequent layers according to the present invention.

First, P ₁ point and P ₂ taught as welding start and end points
Point, a reference point specified to define the offset direction
From R ₁ and R ₂ , the direction cosine ,, is obtained by the following procedure.

i) Obtain from P ₁ and P ₂ .

ii) Obtain from P ₁ and P ₂ .

iii) Perform an operation to obtain the cross product with and obtain

iv) R ₂ is on either side of the plane formed by R ₁ , P ₁ and P ₂ (
Direction from the right side to the left side), R ₂
Turn to the side with.

Next, the offset amount RA on the robot coordinates is obtained from the offset amount setting value A. That is, the calculation RA = A × is performed.

Similarly, the offset amount RB on the robot coordinates is obtained from the offset amount setting value B. That is, RB = B ×
Is calculated.

By the above, the offset direction and offset amount are obtained, and the motion locus of the second layer Can be obtained. Even in the third and subsequent layers, the motion locus can be obtained by similarly obtaining the offset direction and the offset amount.

〔Example〕

 Hereinafter, the present invention will be specifically described based on Examples.

FIG. 2 is a block diagram showing a configuration example of a robot controller for carrying out the multi-layer welding method of the present invention, and FIG. 3 is a flowchart showing a processing procedure.

In FIG. 2, reference numeral 1 denotes a robot controller, which is a position data storage memory 2, an offset amount storage memory 3, an offset amount conversion unit 4, a scaling calculation unit 5, and a robot interpolation calculation unit 6.
Is equipped with.

The processing by the robot controller 1 of FIG. 2 will be described with reference to the flowchart of FIG.

First, the working point and the reference point are taught to the robot (steps 10 and 20). The position data obtained by the teaching is stored in the position data storage memory 2. Next, the offset amount is set in the offset amount storage memory 3 (step 30).
As the offset amount, a vertical offset amount and a horizontal offset amount are given. Since the position data and the offset amount are given as data in the absolute coordinate system, the offset amount conversion unit 4 uses the calculation method described with reference to FIG. Convert to an offset amount (step 40).
Next, the calculation of scaling, that is, the calculation of each point of the motion locus of each layer is performed, and the calculation result is stored in a memory area different from the position data storage memory 2 (step 5).
0). The robot interpolation calculation unit 6 in FIG. 2 performs interpolation calculation based on the obtained start point coordinates and end point coordinates, and performs robot work based on the data (step 60).

〔The invention's effect〕

As described above, in the present invention, when teaching the first layer, the reference point is taught, the horizontal shift amount of each layer,
The vertical shift amount is set as a parameter, the direction cosine in the horizontal and vertical directions, which is the scaling shift direction, is found from the teaching start point, end point, and reference point, and the movement locus of the second and subsequent layers is determined from this scaling shift direction and shift amount. Since the reference point is taught to the first layer and the shift amount is set to the second layer or later, the subsequent multi-layer welding can be automated and the operation by the operator becomes extremely easy. Further, since the shift in the vertical direction is also taken into consideration, the three-dimensional shift can be easily performed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a method of obtaining an offset direction and an offset amount, which is a basis for obtaining a motion locus of the second and subsequent layers according to the present invention, and FIG. 2 is a robot for carrying out a welding method according to the present invention. FIG. 3 is a block diagram showing a configuration example of the control device, and FIG. 3 is a flowchart showing a processing procedure according to the present invention. 1: Robot controller 2: Position data storage memory 3: Offset amount storage memory 4: Offset amount conversion unit 5: Scaling calculation unit 6: Robot interpolation calculation unit

Claims (1)

[Claims] 1. When teaching the first layer, a reference point is taught, the horizontal shift amount and the vertical shift amount of each layer are set as parameters, and the scaling shift direction starts from the teaching start point, the end point, and the reference point. A multi-layer welding method characterized in that the horizontal and vertical direction cosines are obtained, and the operation loci of the second and subsequent layers are calculated from the scaling shift direction and the shift amount to perform multi-layer welding.