JPS61276775A - Wire feeding device for tig arc welding - Google Patents

Abstract

PURPOSE:To perform a stabilized melting control even in automatic TIG welding by changing the wire feeding speed corresponding to the size of the extension and by providing the extension section to hold the reference feeding speed in the TIG welding adding a wire. CONSTITUTION:The reference feeding speed is provided in the wire feeding speed and extension in the wire feeding device for TIG welding made so as to decided the feeding speed of a wire corresponding to the size of the extension of the wire. For example, the wire feeding speed is taken at the value 0.25 times of the reference feeding speed in case of more than 40mm extension and at the value 1.75 times in case of less than 10mm extension. In case of the extension within the range 20-30mm the reference feeding speed is taken.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a wire feeding device, and more particularly to a wire feeding device suitable for semi-automatic hot wire TIG (tungsten inert gas) arc welding. .

[Prior art]

FIG. 4 is a diagram for generally explaining the prior art, and shows a hot wire TIG welding device, which is a type of automatic TIG welding, and feeds the additive wire while heating it with electricity.

As shown in the figure, an arc power source 3 for DC welding is connected to the tungsten blade 1 and the base metal 2, and an arc 4 is formed in argon shield ψ gas with the tungsten electrode 1 as the negative electrode. Addition wire 5 is routed from wire feeder 6 to conduit 7
The wire passes through a wire guide 9 consisting of a connected contact tip 8 and the like, and is guided to an arc generating part and comes into contact with the base material 2. In this case, a wire power source 10 is connected between the contact tip 8 and the base material 2, and direct current or alternating current is passed through the additive wire 5 to generate Joule heat.

This increases the melting rate of the additive wire 5.

By the way, 1. In normal manual TIG welding.

The additive rod (for example, diameter 2 nn, length 600 mm+) is held in one hand and the TIG torch is held in the other hand while supplying the metal to be welded with one hand, or welding is performed without additive metal. On the other hand, in 1. normal automatic TIG welding, the additive metal is supplied by a wire feeding device that automatically feeds the wire, but the wire guide and TIG arc torch are both fixedly held on a stand, etc., and then attached to a welding cart. Welding is carried out after mounting the machine.

Semi-automatic TIG welding employing both of these configurations is known, and FIG. 5 shows a commercially available semi-automatic TIG welding torch. A hand-held TIG torch main body 11 and a wire guide 9 are semi-fixedly attached, and the wire 5 is automatically fed at a predetermined speed by a wire feeding device (not shown). Since the tip of the wire 5 needs to be added to the correct position in the molten pool 12 formed by the arc 4, an adjuster 13 is attached to the TIG torch body 11 to finely adjust the wire addition position. A person can hold such a torch 14 in one hand, adjust the torch position, and use the other hand to operate a knob on the remote control box of the wire feeding device (not shown) to adjust the wire feeding speed. I can do it. In the case of the cold wire method in which the wire 5 is not heated with electricity, the wire 5 is normally fed from the welding direction side as shown in FIG. On the other hand, in the hot wire method in which the wire 5 is heated with electricity.

Usually, the wire 5 is added from the rear in the direction of welding progress.

By the way, when trying to change the welding direction during WI welding, it is necessary to change the wire addition position as well. Therefore, it would be good if the addition position of the wire 5 could be adjusted by adjusting the adjuster 13.

TIG arc 4 requires delicate arc length control
However, it is difficult to perform these operations simultaneously. In the end, the adjuster 13 cannot be used during welding, and the wire guide is fixed to the torch body 11 in order to change the direction of the welding progress by changing the direction of the entire welding torch 14 in semi-automatic TIG welding. , the torch 14 becomes directional, which significantly impairs the flexibility of welding operations.

Therefore, if you try to weld by holding the torch body 11 in one hand and the wire guide 9 in the other hand, you will not be able to perform remote control such as adjusting the feeding speed of the additive wire 5 or adjusting the arc current. arise.

In addition, when welding by holding the additive rod with one hand, the melting of the additive rod can be adjusted freely, but the additive wire 5 is not automatically fed at a predetermined constant speed, but in semi-automatic welding, the additive wire 5 is stretched. A balance must be maintained with the actual melting speed of the wire, and as a result, the distance between the tip of the wire guide 9 and the base metal, that is, the extension e, gradually increases, making it difficult to sustain welding.

Furthermore, in the case of normal hot wire 'r IG welding,
The arc 4 is caused by the wire heating current flowing through the additive wire 5.
Since so-called magnetic blowing occurs, if the torch body 11 and wire guide 9 work separately, the magnetic blowing situation will not be determined and a stable welding result cannot be expected.

For these reasons, a torch 14 in which a torch body 11 and a wire guide 9 are integrated as shown in FIG. 5 is actually used, and although semi-automatic TIG welding is in great demand, Due to various problems, it was not widely adopted.

Therefore, the present applicant previously proposed a semi-automatic TIG welding method using hot wire switching TIG welding. Here, the hot wire switching TIG welding method is as shown in FIG.

Using a pulsed arc, the wire current is not passed during the peak arc current period TP, but the wire current is passed during the base current period Tb, where the arc current is very low, to eliminate arcing, which is a serious problem in hot wire TIG welding. This virtually eliminates magnetic blowing. There, the special application 1983-
The hot wire switching TIG power supply disclosed in Japanese Patent Application No. 177124 is used, and the wire heating power is controlled by the method of Japanese Patent Application No. 186998/1982.

This is done by controlling the wire energization period tw based on the idea of supplying wire heating power commensurate with the wire feeding speed. In addition, the wire voltage and wire current between the extensions are detected and input into a dividing circuit to obtain the wire resistance value between the extensions. The relationship shown in Figure 7 applies over a wide range regardless of factors such as mild steel, wire diameter l.

2nn example) is established, and the size of the extension and the resistance value are related.

Based on the correspondence between the extension and the resistance value of the wire detected in this way, the wire feeding speed is changed in accordance with the size of the extension as shown in FIG.
I tried semi-automatic TIG welding in this way.

Using this device, it has become very easy to weld by holding a TIG arc torch in one hand and a hot wire feeding guide in the other, but the wire extension can be kept constant using the torch in hand. Since it is quite difficult to maintain the melting rate of the wire, there is a tendency for the melting rate of the wire to fluctuate constantly, which makes it rather difficult to form a beat with a stable shape.

[Purpose of the invention]

This invention was made in view of the above-mentioned problems, and in TIG welding where the wire is automatically fed, one hand holds the wire feeding guide and the other hand holds the TIG arc welding.
An object of the present invention is to provide a wire feeding device for TIG welding that has a relationship between wire extension and feeding speed so that semi-automatic TIG welding with a torch can be more easily performed.

[Key points of the invention]

In short, this invention enables automatic TIG welding by providing an extension section in which the wire feeding speed is changed according to the size of the extension and maintaining a predetermined standard feeding speed in TIG welding in which wire is added. This allows for stable melting control.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention implemented using a hot wire switching T I Gil source suitable for semi-automatic TIG welding.

3 is a flowchart showing the operating steps of the device. The present invention will be described in detail below based on two flowcharts.

First, for welding, specify arbitrary values such as arc current and standard wire feed speed suitable for the target workpiece, and perform TIG
The arc is started by holding the torch body 11 in the right hand and the wire guide 9 that automatically feeds the additive wire 5 in the left hand. When the base material reaches t81 km and a molten pool 12 is formed, the wire guide 9 is brought closer and the tip of the additive wire 5 is inserted into the molten pool 12. Then, it is detected that the wire 5 and the base material 2 are in contact with each other, and a command signal is outputted to start wire feeding.

On the other hand, the wire is energized periodically as shown in Fig. 6, and the wire current waveform and the wire voltage waveform generated between the contact tip 8 and the base material 2 are detected and the 1 division circuit is used. The resistance value at the long extension of the doped wire 5 between the contact tip 8 and the base material 2 is determined.

As shown in Figure 2, when the extension is 40 m or more, the wire feeding speed is set to 0.25 of the standard feeding speed.
If the extension is 10+s or less, the value will be multiplied by 1.75, and if the extension is 2011I
When the extension was within 30 mm from I+, the reference feeding speed was maintained, and when the extension was 10 to 201 m, or 30 to 40+w+, the relationship was made by connecting each with a straight line as shown in FIG.

Welders can now specify their desired wire feed speed as the standard feed speed before starting welding. In this way, the wire feeding speed is determined in accordance with the extension by providing a polygonal relationship. on the other hand.

The relationship between the wire heating power and the wire melting rate when the wire is heated with electricity in the absence of an arc is a linear relationship as shown in FIG. 9. However, during actual arc welding, due to radiant heat from the arc, heat transfer from the molten pool, and contact with the arc plasma.

Even in a so-called cold wire state where no current is applied to the wire, the wire melts to a small extent. It is known that the maximum melting speed at which the wire can be properly melted in that state varies considerably depending on the wire insertion position and direction, as well as the A1 current value. and.

In the case of a hot wire, it is known that as the wire melting rate increases, it approaches the value shown in FIG. Here are the results of these experiments.

V (g/m1n) =0.05 P (W)-0,0
5I am (A) ie.

P(W)=20V(g/l1lin) Iam(A)
A control circuit was constructed to determine the wire heating power according to the following empirical formula. Here, ■ is the melting rate of the wire, P
is the applied power for wire heating and 1 am is the average arc current. Then, compare it with the temporal average value of the actual wire heating power obtained as the product of the detected wire current waveform and wire voltage waveform, and increase or decrease the wire energization time.
The power applied to the wire is controlled by feedback.

Also, although the wire current is within the period during which wire energization is instructed, the wire current is zero, that is, the base material 2 and the wire 5 are not in contact, which often occurs during actual work. In this case, the original wire feeding speed was maintained for 1 second, and the circuit was configured to stop wire feeding when the wire was still not energized. Then, when starting the next welding operation, set the wire to an appropriate protrusion length.

After another 2 seconds had elapsed from the wire feeding stop state, the wire feeding motor was reversed to move the wire back about 10 mm.

Since the present invention has such a configuration, welders can now perform semi-automatic TIG welding very easily while controlling the wire feed speed in exactly the same way as TIG welding with a regular additive weld. . In particular, by providing an extension section that maintains the standard wire feeding speed, welders can maintain a constant standard speed even if their hands move slightly involuntarily, and can actively change the extension to feed the wire as desired. It is now possible to increase the feed speed and then easily return to the original standard feed speed.

[Other embodiments of the invention]

The present invention is not limited to application to hot wire switching TIG welding.
Even in welding, it was sufficiently applicable when the wire current was relatively low. Furthermore, the wire is not intended for heating;
It is also possible to conduct semi-automatic TIG welding using a cold wire by passing a very low current just to detect the resistance value of the extension part.

Furthermore, the polygonal line relationship between the extension and the wire feeding speed is not limited to the one shown in Part 2, but as shown in Figure 3, when the extension is small, the feeding speed is slowed down, and when the extension is When the size is large, the feeding speed can be increased. In this case, the feed speed will be controlled in the opposite way to the welder's normal welding work sense, but if the welder's hand movement is a little too fast, it will compensate for the movement. It has an effect. That is, when pulling up the hand to increase the wire feeding speed and increase the extension, if the hand is pulled up too quickly, the tip of the wire may separate from the base material and the wire cannot be energized. As the wire feeding speed increases, such a situation becomes less likely to occur.

[Effects of the Invention] According to the present invention, semi-automatic T.I.
Since Gl welding has become very easy to perform, TIGfl has a high quality and can be applied to welding work in any position, and has a wide range of applications, but it has the problem of low work efficiency. The work efficiency of TIG welding is greatly improved, and the field of application of TIG welding can be significantly expanded.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the configuration of the present invention. 2 and 3 are characteristic diagrams showing the relationship between the extension and wire feeding speed according to the present invention, and FIG. 4 is an explanatory diagram of a generally used hot wire TIG welding device,
Figure 5 is an explanatory diagram of a conventional semi-automatic TIG welding torch, Figure 6
Figures (a) * (b) are arc current characteristic diagrams and wire current characteristic diagrams, Figure 7 is a characteristic diagram showing the relationship between extension and resistance value, and Figure 8 is a characteristic diagram showing the relationship between extension and wire melting rate. 9 are characteristic diagrams showing the relationship between wire heating power and wire melting rate. 5... Addition wire, 3... Wire feeding device, 11... Torch body, 14...
torch. Figure 1 Figure 2 Figure 3 Extension (mm) Figure 6 Figure 7 Extension (mm) Figure 8 Extension (mm)

Claims (1)

[Claims] 1. In a wire feeding device for TIG arc welding configured such that the wire feeding speed is determined in accordance with the size of the wire extension, there is no reference between the wire feeding speed and the extension. A wire feeding device for TIG arc welding, characterized in that a feeding speed is provided, and where the extension changes from that section, the wire feeding speed is changed depending on the size of the extension. 2. In claim 1, where the wire feeding speed is shorter than the section between the wire feeding speed and the extension where the reference feeding speed is provided, the wire feeding speed is set higher than the section where the extension is shorter than the section between the wire feeding speed and the extension. A wire feeding device for TIG arc welding, characterized in that it is equipped with a mechanism that slows down the wire feeding speed where the wire feeding speed is large. 3. In claim 1, where the wire feeding speed is shorter than the section between the wire feeding speed and the extension where the reference feeding speed is provided, the wire feeding speed is lowered and the extension is larger than the section. By the way, a wire feeding device for TIG arc welding is characterized by being equipped with a mechanism for increasing the wire feeding speed.