JPS6313668A - Welding conditions control method - Google Patents

Abstract

PURPOSE:To correctly control welding conditions by detecting a certain constant length from a welding start point and the temp. area of a molten pool and performing a heat input controlling with the average value thereof as the reference temp. area. CONSTITUTION:A molten pool 15 is observed by an infrared rays camera, a multivalue constant temp. line diagram is made by an infrared rays pick-up device 18 and the bivalent picture image shown in the figure is made by segmenting the diagram at >= a constant temp. by an image processing device 8. For a certain constant length after starting the welding this operation is subjected to a sampling on each a fixed time and its averaged one is taken as the reference temp. area. And this value is compared with the reference value by a computer 16, the welding speed deviation and welding current deviation are calculated and outputted via a welding control device 4. The effect of the material, plate thickness, groove shape, etc. is allowed to include the reference temp. area, so a correct welding control can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the control of welding conditions in narrow gap hot wire TIG welding, and in particular to a welding method suitable for controlling heat input of a molten pool. Related to condition control method.

[Conventional technology]

Conventional welding control methods, as described in JP-A-58-16774, detect the surface temperature of the molten pool and control welding conditions according to the detected temperature.6 However, This surface temperature is affected by the characteristics of the welded material (material thickness, groove shape) and the number of weld layers, so it is necessary to determine the reference temperature each time, and when controlling the welding conditions, It required a huge amount of data.

[Problem that the invention seeks to solve]

The above conventional technology does not take into consideration the effects of material, plate thickness, groove shape, and number of weld layers when setting the reference temperature.In order to set the reference temperature including these effects, It was necessary to conduct a large amount of experiments and collect data.

One aspect of the present invention is that even if the material, plate thickness, groove shape, and number of welding layers of the welded object change without conducting a large number of welding experiments, the standard temperature area can be set and the welded object and welding conditions can be adjusted. The objective is to perform heat input control in accordance with the

[Means for solving problems]

The above purpose is 7W contact point or 1゛; a certain length,
This is achieved by detecting the temperature surface I of the molten pool, finding the average value of Vll, and using this as the reference temperature area.

[Effect]

Even if the characteristics of the workpiece (material, plate thickness, groove shape), number of welding layers, or welding conditions change, the reference temperature area can be set online.

〔Example〕

An embodiment of the present invention will be described below.

First, the overall configuration of the present device will be explained with reference to the general diagram of the present device shown in FIG.

This device holds and opens (:I
) A welding drive device 2 that can be controlled to any position within the tip 12, a wire feeding device 3 that feeds the wire 14 to the welding part, a welding power source 6 that supplies power to the welding torch 1, and a heating device that heats the wire 14. A TIG welding device consisting of a mold g5 and a welding condition control device 4 that directly controls these, an infrared camera 7 that observes the molten pool 15, and signals from the molten pool]-
The system includes an image processing device 8 that calculates H1 of the temperature distribution of 5, and a system control panel 9 that sends and receives signals between the welding condition control device 4 and the welding condition control device 5.

Next, the operation will be explained.

As shown in FIG. 3, the infrared camera 7 is fixed to the torch 1 and observes the molten pool 15 from diagonally above.

The welding drive device 2 has three orthogonal operating axes,
As shown in FIG. 3, the welding torch 1 can be moved up and down, right and left, forward and backward nine times with respect to the groove 1.

The welding wire 14 is connected to a feeding motor 16 of the wire feeding device 3.
It is fed to the molten pool 15 by this.

The welding wire 14 is connected to the power supply chip 1 in order to increase the amount of welding.
It is electrically heated by the heating power supply 5 via the heating power supply 7 .

Next, the content of welding control of this device, including its operation, will be explained with reference to FIG. 4.

By observing the molten pool 15 with the infrared camera 7, the infrared imaging device 18 displays a multivalued isomixture diagram of the molten pool 15 as shown in FIG. 5 on the internal monitor 20 with a 16-level gray code. , outputs an image signal 19 of a multivalued isotherm diagram as shown in FIG. 13 to the outside.

The image processing device 8 uses the internal microcomputer 1 to generate a binary image as shown in FIG. 6, which is a multivalued isothermal diagram of the molten pool cut out at a certain temperature or higher.

Next, from this binary image, the microcomputer calculates the position within the groove of one heave 1 and the welding heat input.

Based on this calculated value, computer 1 in the system control panel
6, the welding speed deviation compared to the reference value.

The welding current deviation is calculated and outputted to the welding condition control device 4 as information 17 on the welding conditions and torch position.

Upon receiving this signal, the welding condition control device controls the position of the torch 1, controls the feed speed by the motor control device, and controls the heat input to the molten pool 15 via the welding power source 6 and heating power source 5. control.

Next, when the welding heat input is controlled by the temperature area in the vicinity of the molten pool, as proposed in this patent, a method for determining the reference temperature area will be described below.

Varies depending on the situation.

As a specific example, FIGS. 6 and 8 show how the size of the binary image changes as the number of welded layers changes.

In other words, the area Si of the binary image when welding the i-th layer in FIG. 7 and the area S l+1 of the binary image when welding the i+1 layer in FIG. The layers are larger.

Therefore, when trying to weld the five layers 11 and i -1-1, lf # 11 & under the same welding conditions, a certain reference value is set in advance as described above, and -r r;
Since the size of the binary image changes, the welding condition control panel controls the welding conditions so that the area of the binary image of the molten pool is equal to the area of the reference value. The welding conditions will be different from the actual welding conditions.

Therefore, it is necessary to set reference values that include the effects of these welded product characteristics and the number of welded layers.

This method will be explained below with reference to FIGS. 11 and 12.

As shown in Fig. 11, during the learning period and the welding condition control period for full weld length and welding, reference values including the effects of the welding material characteristics and the number of weld layers are set during welding during the learning period. This is how to set it.

The control method in this case will be described below using the welding condition control flowchart 1- in FIG. 12.

First, input data such as welding conditions are incorporated and the data is checked. When this data is OK, welding is started, and when it is No, the data is reset.

Next, welding is started, and during the welding learning period, the area of the binarized image of the molten pool is sampled at regular intervals, and at the same time, although not mentioned in this patent, the torch is applied to the groove. The position of the torch is detected and the torch position is corrected. This is to prevent the temperature area from changing if the torch is biased against the groove during welding compared to when the torch is in the center of the groove.

Next, after the welding learning period is over, as shown in Fig. 10 of the welding condition control law, the standard area upper limit S 1ma
+may= (1+K) S −, S 5−s−=(
Calculate and set as 1+K)S. Here, K is a constant determined empirically.

Thereafter, the heat input state and the torch position are detected, and the heat input and torch position are corrected and controlled until welding is completed.

FIG. 14 shows a control flowchart for welding heat input.

The left side of the figure represents the case where the welding heat input is larger than the allowable range, and the right side represents the state when it is smaller than the allowable range.

As can be seen from the figure, welding heat input is controlled by welding speed
, base current ■B, base wire speed WB, peak current 1. I), with peak wire speed WP.

The control order of welding conditions is welding speed, base current, base wire speed, peak current, and peak wire current.

[Effects of the Invention] According to the present invention, the standard temperature area that serves as a reference when controlling welding conditions includes the influence of the characteristics of the welded product such as material, plate thickness, and groove shape. It is now possible to accurately control welding conditions when welding two pieces of the same weld line.

[Brief explanation of drawings]

Fig. 1 is an overall view of one embodiment of the present invention, Fig. 2 is a sectional view of a (1υ narrow gap), Fig. 3 is a configuration diagram of the welding head, and Fig. 4
The figure is a configuration diagram of this device, and Figure 5 is a multi-value equimixture diagram of the molten pool.
Figure 6 is a binary image of the molten pool when the i layer is welded, Figure 7
The figure is a cross-sectional view of the groove when layer i is welded, and Figure 8 is j+1.
A binary image diagram of the molten pool when the layers are welded, Figure 9 is i +
A cross-sectional view of the groove when one layer is welded, Figure 10 is the i layer and j layer.
Diagram showing the change in temperature area when +1 layer is welded, 1st
FIG. 1 is a state diagram of control of a welded object, FIG. 12 is a control flowchart of welding conditions, FIG. 13 is an image signal diagram, and FIG. 14 is a flowchart of welding heat input control. 1... Welding torch, 2... Welding drive device, 4...
Welding condition control device, 5... Heating power source, 6... Welding power source, 7... Infrared camera, 8... Image processing device, 9
...System control panel, 15... Molten pool.

Claims (1)

[Claims] 1. A flat welding torch, a welding drive device that holds it and can move it to any position within the groove, a wire feeding device that feeds the wire, and a welding power source that supplies power to the welding torch. , a welding device consisting of a heating power source to heat the wire, a welding condition control device to control welding conditions, an infrared camera to observe the molten pool, and an image to calculate the temperature area of the molten pool from the signals from this. This welding device consists of a processing device and a system control panel that sends and receives signals between this and the welding condition control device.The welding device determines the area of the molten pool above a certain temperature and performs welding while controlling the welding heat input. Welding conditions characterized in that the temperature area of the molten pool, which serves as a reference for control, is obtained by sampling and averaging the temperature area of a certain length from the welding start point, and using this as the reference temperature area. Control method.