JPS5944149B2 - Dual heating high speed welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for heating a material to be welded by interposing an electrode between the groove surfaces of the material, a welding material heating means for energizing the material to be welded, and a groove surface heating means for energizing an induction coil. This relates to the original heating high speed welding method.

In the conventional electroslag welding method, a core wire serving as an electrode and flux are inserted into the gap between the groove surfaces, and the welding material is melted between the groove surfaces by utilizing the resistance heat generation of the core wire and molten slag due to energization. Continuous welding is performed by creating a pool of molten metal, applying a patch plate to the side of the gap to prevent the molten metal from flowing out, and gradually moving the patch plate upward while cooling the pool. It is.

Therefore, conventional electroslag welding has the following problems.

(1) Heat input is very large, causing embrittlement.

This heat input is 300,000 to 400,000 joules 1c for a plate thickness of about 25n.
m is required, compared to other MIG and TIG welding.
It corresponds to ~3.

Therefore, when the material to be welded is a heat-treated material, the material to be welded loses its luster, and metallurgically, the crystal grain size becomes coarse and becomes brittle. Therefore, although it is currently applied to welding boilers and the like that can be heat treated after welding, it is not suitable as a welding method for shipbuilding. (2) The gap between the groove surfaces cannot be made small.

The gap between the groove surfaces cannot be reduced to less than 20-28 m1 degree with today's technology.

If it is less than 20 mm, the volume of the molten slag bath is small and the amount of heat is insufficient, so that it cannot fully fuse with the material to be welded, and defects such as poor fusion are likely to occur. (3) Welding speed is limited.

Currently, the welding speed of electroslag welding varies depending on the plate thickness, but in the case of a blade with a plate thickness of 25 m, it is about 50 V/1n.

This welding speed is as specified in (1) above. It is difficult to increase the temperature further due to the amount of heat in (2). The shield gas arc welding method using shield gas instead of the slag of the electroslag welding method described above also has the same problems as above.

The conventional electroslag welding method has the advantage that it can be used for vertical joints and circumferential welding of thick plates, as well as for welding large parts of huge heavy machinery, but as mentioned above, the heat input is large and the gap between the groove surfaces is The gap is 20m77! There is a problem that it is not possible to do the following, and the same problem applies to the gas shield welding method. In view of this point, the present invention focuses particularly on the molten interface on the groove surface,
"The groove surface of the welded material is rapidly preheated to a temperature higher than the melting temperature by the heat of the molten metal!" This is a welding method developed based on the idea of ``performing gas shield welding''.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be explained with reference to the drawings in terms of embodiments.

Example 1 This example relates to a dual-heat welding method for longitudinal joints of thick plates, in which electroslag welding is performed in combination with rapid heating of the groove surface.

(See Figures 1 to 4) 1, 1 is a material to be welded having parallel groove surfaces 6, 6 extending in the vertical direction and facing each other, 2 is molten slag, 3 is a core wire (decorrosive electrode), 4 and 5 are water-cooled copper walls, which are arranged in the same manner as in conventional electroslag welding. In the gap 7 between the groove surfaces 6, 6, a cooling type high frequency induction coil 8 is inserted into which a tube 11 as shown in FIG. 4 is wound flat and water is passed through the tube. This welding method is the same as conventional electroslag welding in that the material to be welded 1, the molten slag 2J, and the welding rod 3 are energized. The area around 6 is heated by induction.

By this induction heating, the groove surfaces 6, 6 and their vicinity are raised to an appropriate temperature at which they are melted by the molten metal in the pool 9. Water-cooled copper walls 4, 5, high-frequency induction coil 8 are in pool 9
of the molten metal at a rate corresponding to the rate at which it solidifies. The core wire 3 is reciprocated in the direction of the groove, similar to conventional electroslag welding. Further, the number of core wires 3 increases as necessary. 10 is solidified weld metal.

To describe an example of the high frequency current applied to the high frequency induction coil 8, the frequency is 50 KHz and the heat flow is 0.5 KW.
/Cd, and when the penetration depth of the groove surfaces 6, 6 of the material to be welded is 0.2 cm, the surface temperature of the groove surfaces 6, 6 will reach 1000°C in 2 seconds of heating time. .

When the plate thickness of the material to be welded 1 is 257 fLm, the gap 7 is 10
mm, the number of core wires 3 is two, and the total current is 800 amperes, the welding speed can be 30 crn/min. To further explain the above-mentioned core wire 3, this core wire 3 serves as both an electrode and a welding material, and is melted into molten metal by the resistance heat generation of the current flowing through the core wire 3 and the molten slag 2. It is a metal electrode rod.

That is, in this case, the welding material is the core wire 3, and when iron powder and alloy additives are added to the flux, this flux also becomes part of the welding material. Note that it is of course possible to change the core wire in the above embodiment to a non-fusing type electrode that does not wear out.

In the case of this non-fusing electrode, an arc is generated by a substantially non-consumable electrode such as a tungsten rod, and a core wire as a welding material is supplied from above to the arc portion and melted.
It is filled between the groove surfaces. Example 2 This example relates to a dual-heat welding method for longitudinal joints of thick plates, in which gas-shielded arc welding is combined with rapid heating of the groove surface.

(FIG. 5) The apparatus of this example is similar to the apparatus of Example 1, except that the slag 2 is not used and a shielding gas is used. A shielding gas (argon gas, helium gas, or a mixture of both) is vented through the gas pipe 14 to the top of the electrode 13 in the groove surface gap to create an inert gas atmosphere. arc 15
is generated, and the welding material is melted by the heat generated by the discharge to form molten metal 9. The other points are the same as in the first embodiment. As described above, the present invention involves intervening a groove surface heating means that energizes another high-frequency induction coil in the groove surface gap in the electroslag welding method or gas shield welding method, and performs resistance heating of the electrode and molten slag or welding with the electrode. Since this is a welding method that heats the surface of the groove at the same time as arc heating between the materials, this surface is melted in an extremely short time by the molten metal in the pool created by melting the welding material. The connection is made perfectly.

Therefore, according to the method of the present invention, as shown in FIG. 6, in the vicinity of the groove surface Ba of the welded material Aa, the welded material A of conventional electroslag welding or gas shielded gas welding is
Compared to the vicinity of the groove surface Bb in Fig. b, the molten zone of the welded material can be made very narrow as Ca compared to Cb, and the heat affected zone can be made very narrow as Da compared to Db. In addition, according to the method of the present invention, the temperature distribution rises rapidly around the groove surface like Ta, whereas in conventional electroslag welding, it spreads to the outside of the groove surface like Tb, and Heat input is very low. From the above, the method of the present invention can significantly reduce the embrittlement of the welded material since the heat input is much smaller than the conventional method. Further, if the width required for inserting the heating means into the gap between the groove surfaces is 10 mm, it can be narrowed to that width, and therefore no fusion defects will occur. Furthermore, the welding speed can be significantly increased compared to conventional methods. Therefore, it is possible to perform electroslag welding on conventionally heat-treated materials that are unsuitable for electroslag welding, and it can be used particularly for welding in shipbuilding, and the energy saving effect is also significant for large base materials. It is.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention; FIG. 1 is a perspective view showing a vertical section of the groove in the welded state of Example 1, FIG. 2 is a sectional view taken along line A-A in FIG. Figure 3 is a plan view of the state shown in Figure 1, Figure 4 is a side view of the high frequency induction coil, Figure 5 is a diagram of Example 2 corresponding to Figure 2 of Example 1, and Figure 6 is a temperature distribution diagram. It is. 1... Material to be welded, 2... Molten slag,
3... Core wire, 4... Water-cooled copper wall, 5...
...Same as left, 6...Welded end surface, 7...
・Gap, 8...High frequency induction coil, 9...
... Pool of molten metal, 10 ... Welding material, 11
...Pipe, 12...Water passage, 13...
...Electrode, 14...Shield gas pipe, 15...
····arc.

Claims (1)

[Claims] 1 A welding material that generates molten metal, an electrode, and an induction coil are interposed between mutually opposing parallel groove surfaces extending in the vertical direction of the material to be welded, and the material is applied to the side surface of the groove portion of the material to be welded. A plate is provided, and the material to be welded is melted by resistance heat generation or discharge heat generated by current flow between the electrode and the welded material.At the same time, the groove surface is rapidly preheated by passing high frequency current through the induction coil, and the contact plate and electrode are melted. , a dual heating high-speed welding method characterized by moving an induction coil upward.