JPH0771745B2 - High-speed joining method for running steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a high-speed running-fast joining method for steel sheets used in continuous hot rolling of an iron making machine.

<Prior Art> When a steel sheet is hot-rolled, a steel sheet having a certain fixed length is usually supplied to a rolling mill intermittently and rolled. In this case, shape defects occur at the leading and trailing edges of the steel sheet, and the product is not retained because it is cut off. More opportunities to create,
There were problems such as roll replacement costs and loss of time for rolling stoppage due to roll replacement.

Therefore, if a plurality of steel plates are connected in advance and continuously rolled, the above problem is solved and the productivity is significantly improved.

Generally, in the case of continuous cold rolling or continuous pickling of a relatively thin steel plate (10 mm or less), a method of connecting the preceding steel plate 2 and the following steel plate 1 by flash butt welding or the like as shown in FIG. However, since the plate thickness is large (50 to 200 mm) in the hot rolling process, the capability of the welding equipment is insufficient and it is difficult to join the entire cross section in a short time.

For this reason, as shown in FIG. 6 or FIG.
The two end portions are overlapped, and the nail-shaped material 7 is driven in, welded and temporarily fixed, and then rolled. However, the plate thickness is 50
If it is more than mm, it cannot be adopted, and even if the plate thickness is 20 to 50 mm, it is necessary to take a long overlapping part (100 m or more), and this part requires a special preloading process different from the normal part. there were.

<Problems to be Solved by the Invention> An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method capable of high-speed joining of high-temperature thick plates in a short time.

<Means for Solving Problems> The configuration of the present invention that achieves such an object is a step of running a plurality of steel sheets back and forth and performing hot continuous rolling, while running a high temperature steel sheet and By increasing the traveling speed of the trailing steel plate, these are collided and pressed for a certain time, while during pressurization, a super large current is passed for a short time between the preceding steel plate and the following steel plate, and resistance heating causes It is characterized in that only these contact surfaces are welded.

<Operation> When an ultra-high current is applied between the preceding and following steel plates, resistance heat generation is proportional to the square of the current, so even a steel plate with a large cross-sectional area can be welded in a short time.

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

FIG. 1 shows an example of an apparatus used in the method of the present invention. The device shown in the figure uses a capacitor. That is,
A leading steel plate (hereinafter referred to as a leading plate) 2 and a trailing steel plate (hereinafter referred to as a trailing plate) 1 are sent by a traveling roller 14 and rolled by a rolling roller 10, and a trailing plate is also used. The drive roller 15 has a speed V ₂ which can be increased or decreased. Power supply chips 3 also serving as clampers are arranged above the leading plate 2 and the trailing plate 1, respectively, and are moved up and down by a pressure cylinder 13 to be pressed against the leading plate 2 and the trailing plate 1. A switch 12 is provided on both feeding chips 3.
The capacitor 11 is connected via the switch, and the capacitor 11 is connected to the DC power supply via the switch 16.

When joining the terminal end surface of the preceding plate 2 and the leading end surface of the trailing plate 1 which are already subjected to the preceding rolling with the apparatus having the above-described configuration, the following process is performed.

First, as shown in FIG. 1 (a), the switch 12 is opened and the switch 16 is closed to apply a DC voltage to the capacitor 11 to charge it, and the driving roller 15 advances the speed V ₂ of the trailing plate 1 ahead. These are made to collide by making it increase from the speed V _{1 of the} plate 2. Leading plate 2 and trailing plate 1 after collision
As shown by the broken line in FIG. 2, the pressing force P of and is kept pressurized for a certain period of time after the collision. Next, during pressurization immediately after the collision, the switch 16 is opened and the switch 12 is closed to discharge the capacitor 11 as shown in FIG. 1 (b). At this time, the welding current I flowing between the leading plate 2 and the trailing plate 1 through the feeding tip 3 has an impulse waveform having a very large current value for a short time as shown by the solid line in FIG. Since resistance heating is proportional to the square of the current value, even if the contact area between the leading plate 2 and the trailing plate 1 is large,
Welded in a short time.

The maximum welding current I is adjusted by the charging voltage of the capacitor 11, and the discharging time is adjusted by the turn ratio of a welding transformer (not shown). Further, as the pressing force P, the collision speed and the driving roll 15
It is adjusted by the driving force of.

Specific implementation conditions are shown in FIG. As shown in the figure, the steel plate is a bar material having a plate thickness of 20 mm, a plate width of 1000 mm and a temperature of 1000 ° C. Welding conditions are maximum current 300000A, welding time 1
The pressure is 10Ton or less and the collision speed is 2m / sec or less. The joint performance joined under the above conditions has no defects, good joint strength,
Bending ductility was obtained. Therefore, continuous hot rolling could be performed without cutting in the subsequent rolling steps.

In the above embodiment, a super large current was obtained by capacitor discharge, but the present invention is not limited to this, and a single pole generator illustrated in FIG. 4 may be used instead of capacitor discharge. Since the single-pole generator can obtain a large current as compared with the capacitor discharge, it is convenient for joining steel sheets having a large cross-sectional area.

<Effects of the Invention> As specifically described above based on the embodiments, in the present invention, because of upset welding using ultra-large current by capacitor discharge or a single-pole generator, a large interruption occurs in a short time energization. Since the steel plates can be joined in a large area and the melting width is narrow, burrs and deformation do not occur and pretreatment such as deburring before rolling is unnecessary. In addition, since the leading plate, the trailing plate, and the speed control device are made to collide with each other to be in a pressurized state, a complicated and expensive pressurizing device is not required and a simple device can be used.

[Brief description of drawings]

FIGS. 1 (a) and 1 (b) each relate to an example of an apparatus for carrying out the method of the present invention. FIG. 1 (a) is an explanatory diagram showing a state before a collision, FIG. 1 (b) is an explanatory diagram showing a state after the collision, and FIG. , A graph showing welding current I and applied pressure P over time, FIG. 3 is an explanatory view showing specific working conditions, FIG. 4 is a perspective view of a single-pole generator that can be used in the method of the present invention, and FIG. (A) and (b) are related to the flash butt welding method, respectively. (A) is an explanatory diagram showing before welding, (b) is an explanatory diagram showing during welding, and (a) and (b) in FIG. 6 are nailing respectively. The law,
FIG. 7A is an explanatory view showing nailing, FIG. 7B is an explanatory view showing rolling, FIGS. 7A and 7B are related to tack welding, and FIG. 7A is tack welding. The same figure (b) is an explanatory view showing rolling. In the drawings, 1 is a trailing plate, 2 is a leading plate, 3 is a power supply tip, 4 is an arc, 5 is a transformer, 6 is a welded part, 7 is a nail-shaped material, 8 is a tack welded part, and 9 is a welding wire. , 10 rolling rollers, 11 condensers, 12 and 16 switches, 13 pressure cylinders, 14 traveling rollers, 15 driving rollers, 17 rotating shafts, 18 rotating plates (conductors), 19 coils, 20 Is a yoke, 21 is a current collector on the shaft side, 22 is a current collector on the rotating plate side, and 23 is a magnetic flux.

Claims (1)

[Claims] 1. In a process of running a plurality of steel plates forward and backward to continuously hot-roll, a high temperature steel plate is run and a trailing steel plate is run faster than a preceding steel plate to collide with each other. While pressurizing for a certain period of time, a super-high current is passed between the preceding steel plate and the following steel plate for a short time during pressing, and only these contact surfaces are welded by resistance heat generation. High-speed joining method.