JPS5912385B2 - Netsuden Tatsuseigi Yoga School - Google Patents

Description

[Detailed description of the invention] The present invention relates to a gas welding method.

Gas welding or gas brazing welding is performed by melting the filler rod and melting or heating the base metal using a gas flame such as an oxygen-acetylene flame. Conventionally, as shown in Fig. 1, the welding process is carried out by holding a torch 1 in one hand, a filler rod 4 in the other hand, and using a gas flame 3 sprayed from a nozzle 2 at the tip of the torch 1. The tip of the filler rod 4 was melted, and the molten metal was welded to the welded part 6 of the base material 5, which was being melted or heated by the gas flame 3.

5 Although such manual gas welding is still limited to manual work, efforts are being made to increase the welding speed in order to improve the efficiency of welding work.

There is a close relationship between the amount of heat possessed by the gas flame, the welding speed, and the amount of melting of the filler rod.Especially when welding thin steel plates, the gas flame must be made larger to improve the welding speed (i.e., the gas flame is If the flow rate is increased), the melting amount of the filler rod increases and the base metal heating rate in the welding direction increases, but on the other hand, the molten metal spreads, the bead becomes wider, and the molten metal becomes 15 In addition to vaporization and deterioration of the weld metal, the base metal around the welded part is abnormally overheated, resulting in a major drawback in that good welding results cannot be obtained. The present invention eliminates these drawbacks and provides a method for increasing welding speed without causing spread of molten metal, abnormal overheating of the base metal, or deterioration of weld metal. In general, the temperature of the base material in a direction perpendicular to the weld line centered on the weld line is shown in a diagram as shown in Figure 2.

That is, by increasing the gas flame 25, the temperature of the base metal is distributed over a wide range on both sides of the weld line as shown by the solid line, resulting in an undesirable abnormal overheating state near the weld line. In addition, how the temperature of the base metal surface at any point P on the welding line changes as the torch moves, can be determined by comparing the temperature of the zone that reaches a constant temperature that allows welding in the direction perpendicular to the welding line. Fig. 3 shows the change in width. In FIG. 3, the horizontal axis shows the time course of the welding operation. In other words, in a state before a certain time 35 in which the torch has not yet reached point P, the weldable temperature band width on the base material in the direction perpendicular to the welding line at point P (hereinafter simply referred to as "weldable temperature band width") is still as narrow as point C, as shown on the left side of Figure 3, but as the torch approaches point P, the weldable temperature band width widens.

At the time when the torch reaches point P, the welding temperature band width is T
becomes. However, even after the torch passes through point P, the welding temperature band width at point P continues to expand, and after a certain period of time, it gradually becomes smaller. This is because even when the torch passes through point P, the temperature of the base metal increases due to heating as shown in Figure 2, so the heat transfer from the surrounding base metal to the vicinity of point P has a large effect. , even after the torch has passed, the weldable temperature band width at point P continues to expand over a certain period of time. Such phenomena cause the spread of the molten metal, vaporization of the molten metal, deterioration of the deposited metal, etc., and therefore have a negative effect on the welding results.

Therefore, if cooling gas is supplied to the semi-solidified weld metal and its surroundings, that is, the part where the torch has just passed and the base metal around it, the heat transfer from there will be extremely small, and the heat transfer from there will be extremely small. The change in the base metal surface temperature in the direction perpendicular to the welding line is as shown by the broken line in Figure 3.

By changing the conditions such as the amount of cooling gas supplied and the supply pressure, the temperature at point P of the base material can be arbitrarily set as indicated by broken lines 1, 2, and 3. For example, if T is the optimum temperature at point P, If the temperature band is within the weldable temperature band, it is possible to prevent the band from expanding further. Figure 6 shows the temperature distribution of the base metal when the torch is located at point P on the welding line, as seen from above, using isothermal lines. The case according to the invention method is illustrated by a broken line.

This figure also shows that in the conventional method, the weldable temperature band width is wider at point P' after the torch has passed than at point P where the torch is currently located, which is why the method of the present invention is adopted. It will be seen that by doing so, it is narrowly limited. As is clear from Figures 2, 3 and 6,
In the present invention, by supplying cooling gas to the semi-solidified weld metal and the surrounding base metal, the heating range of the base metal is narrowed and the temperature gradient between the base metal and the weld metal is increased. Since the heat transfer from the surrounding base metal to the welding part can be made very small, it is also possible to narrow the possible welding temperature range in the direction perpendicular to the weld line after passing through the torch to the minimum necessary.

Even if you try to increase the welding speed by increasing the gas flame and increasing the amount of molten metal from the molten metal rod, there will be undesirable problems such as vaporization of the molten metal, enlargement of the bead, and deterioration of the weld metal. Good welding results can now be obtained without any problems.

Next, an embodiment of the method of the present invention will be explained with reference to FIG.

In the figure, numerals 11 to 16 indicate parts corresponding to numerals 1 to 6 in FIG. In this embodiment, a cooling gas such as nitrogen gas is supplied to the base material 1 from a nozzle 17 provided near the crater 12.
The weld metal 18 in a semi-solid state located immediately after the welding part 16 on 5 and the surrounding base metal 15' are supplied to the weld metal 18 and the surrounding base metal 15' to remove excessive heat input to the weld metal and the surrounding base metal. ing.

In addition to nitrogen gas, cooling gases include air, carbon dioxide,
Hydrogen, argon, helium, etc. can be used. Such cooling gas is applied to the weld metal 18 and the surrounding base material 1.
5' and remove excess heat input, gas flame 13
By increasing the strength of the filler rod, even if the welding speed is increased by increasing the amount of molten metal in the filler rod and increasing the heating rate of the base metal, it is possible to prevent a negative effect on the welding result. Manual gas welding as described above requires considerable skill and has the disadvantage that it is difficult to expect uniform welding results.

Therefore, in order to eliminate such drawbacks, the present applicant has invented an automatic or semi-automatic gas welding method and device in which a long filler rod is continuously supplied to the welding part through the center of the gas flame (patent application). (Sho 47-1123920).

The method of the present invention is even more effective when applied to the method of the present invention. In other words, since the method of the previous invention is an automatic or semi-automatic method, it is easier to increase the welding speed than manual welding. Since excessive heat input to the weld metal can be removed and heat transfer to the weld metal can be controlled, the welding speed can be further increased compared to manual welding. FIG. 5 is an explanatory diagram when the method of the present invention is applied to the above automatic or semi-automatic gas welding method.

The long filler rod 24 is fed into the torch 21 through a guide tube (not shown) by a pair of rollers 29 driven by a feeding device such as a motor, and the gas flame 23 injected from the nozzle 22 is The welded part 26 of the base metal 25 is melted or heated, and the tip of the filler rod 24 that is continuously supplied through the center of the gas flame 23 is melted, and the welded part 26 that has been melted or heated as described above is melted. Welded as gold. Nitrogen as a cooling gas is supplied from a nozzle 27 provided near the crater 22 to the semi-solidified weld metal 28 located immediately after the welding part 26 and to the surrounding base metal 25'. Even if the welding speed is increased by increasing the flame 23 to increase the heating rate of the base metal 25 and the amount of melting of the filler rod 24, a good welding result can be obtained. If done manually, you would operate the filler rod with one hand and the torch with the other, so even if you increase the welding speed by increasing the gas flame, there is a certain limit, but if you use automatic or semi-automatic, especially automatic, you can do this. By applying the method of the present invention, it becomes possible to significantly improve the welding speed.

In addition, when welding is not done on a horizontal plane, such as upward welding or downward welding, there is a problem of dripping of molten metal, which makes automation extremely difficult. By supplying it to a certain weld metal and its surroundings, it is possible to prevent dripping, so it has the great advantage of being able to automate welding work in any position.

In order to supply cooling gas to the semi-solidified weld metal and the surrounding base metal, in the embodiments shown in FIGS. 4 and 5, a separate gas supply nozzle is provided near the crater at the tip of the torch. Alternatively, cooling gas supply holes may be bored in the crater body.

The number of these cooling gas supply holes may be one or more. Furthermore, by changing the cooling gas supply angle, supply amount, supply pressure, and other conditions such as the shape and position of the supply nozzle (supply hole), the amount of heat input to the weld metal and the surrounding base material can be adjusted as desired. This not only allows the welding speed to be increased accordingly, but also
The bead shape of the weld metal can also be freely selected. As described in detail above, the method of the present invention does not adversely affect the welding result by the simple operation of supplying cooling gas to the semi-solidified weld metal on the base metal and the surrounding base metal. , there is a great benefit that can improve the welding speed of gas welding.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the conventional gas welding method, Figure 2 is a diagram showing the relationship between the distance from the welding line and the base metal temperature, and Figure 3 is the relationship between the torch position and the weldable temperature bandwidth of the base metal. FIG. 4 is an explanatory diagram of the gas welding method of the present invention, FIG. 5 is an explanatory diagram of the gas welding method in another embodiment of the present invention, and FIG. 6 is an isothermal diagram when the base material is viewed from above. It is an explanatory diagram of a line. 11...torch, 12...crater, 13
...gas flame, 14...melting rod, 15
...Base metal, 16...Welded part, 17...
...Tuzzle, 18...Welded metal.

Claims (1)

[Claims] 1. In the gas welding method in which a filler rod is melted and welded with a gas flame such as an oxygen-acetylene flame, welding is performed on the base material located behind the welding part with respect to the traveling direction of the gas flame moving on the welding line. Continuously supplies cooling gas only to the semi-solidified weld metal and the surrounding base metal to force excessive heat input that transfers heat from the surrounding area to the base metal and semi-solid weld metal after passing through the flame. A gas welding method characterized by performing welding while limiting the welding temperature band width on the base metal to a predetermined value.