JPH04262805A - Pressure welding method for steel plate by impulse current - Google Patents

Abstract

PURPOSE:To quickly and securely join rolled stocks by forming partial contact parts on both end parts of the widthwise direction in the rear end part of an advanced rolled stock and in the front part of a succeeding rolled stock, setting power feeding clamps and conducting discharging current to a capacitor bank on the side of a power source. CONSTITUTION:When the advanced stock 2 and the succeeding stock 1 run, pressing rollers 10 accelerates the succeeding stock to the advanced stock which advances at a fixed speed and presses it at a fixed load. At the same time, power feeding clamps 5 are pressed by hydraulic cylinders 8 from the upper part to the advanced stock and the succeeding stock. The charged current of a capacitor C connected in a power source circuit is discharged in a short time and impulse current is supplied to contact surfaces at the end parts of the advanced stock and the succeeding stock through a current transformer 7, the power feeding clamp 5. The contact surfaces at the end parts in the direction of the plate width are melted and joined by contact resistance in contact surfaces and volume resistance. In this way, the rolled stocks can be joined quickly and securely and satisfactorily with small electric capacitance.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining rough rolled materials in a continuous hot rolling line in which rough rolled materials are joined and continuously subjected to finish rolling.

0002

BACKGROUND OF THE INVENTION When hot rolling steel materials, usually steel plates of a certain length are intermittently supplied one by one to the rolling material. In this case, not only does the forming process result in defective shapes at the leading and trailing ends of the steel sheet, which results in poor product yield as the steel sheet is cut off, but also the impact load is applied each time the steel sheet is caught in the roll or discharged from the roll. In addition, there are many opportunities for roll defects to occur, and there are problems such as roll replacement costs and loss of rolling stop time due to roll replacement.

[0003] Therefore, a plurality of steel plates were prepared in advance as shown in Fig. 8 (
As shown in a), if they are connected at the opposing surfaces 11a and rolled continuously with the rolling rolls 4, the above problem will not occur and productivity will be greatly improved. As a result, in general, when a relatively thin steel plate (10 mm or less) is subjected to continuous cold rolling or continuous pickling, steel materials 1 and 2 are joined by flash butt welding or the like as shown in Fig. 8(b). However, in the hot rolling process, the plate thickness is as thick as 20 to 50 mm, so the current capacity to be supplied by the current transformer 7 and the power supply clamp 5 is insufficient, and the entire cross-sectional area is reduced by the arc 6 and the pressure P. It is difficult to join in a short time.

Therefore, as shown in FIG. 7, the front and rear steel plates 1
, a method has been proposed in which the two ends are overlapped and then a nail-shaped material 3 is driven in, or they are temporarily fixed by welding and then pressed together with a rolling roll 4, but this method requires a special pressing process and is not suitable for uniform running. However, there are various problems in achieving the goal of bonding in a short time, and it has not been put to practical use.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for impact current pressure welding of steel plates, which enables rolling materials to be joined together reliably in a short period of time.

[0006]

[Means for Solving the Problems] The present invention achieves the above objects in a continuous rolling line in which the trailing end of the preceding rolled material and the leading end of the trailing rolling material are joined and continuously rolled. At least one of the facing surfaces of the rear end of the preceding rolled material and the front end of the trailing rolled material is processed so that only both ends in the sheet width direction are in contact with each other, and the rear end of the preceding rolled material is processed. The contact surfaces formed at the ends of the opposing surfaces of the front end of the leading rolled material and the leading end of the trailing rolled material are pressed against each other, and a power supply clamp is attached to the rear end of the leading rolled material and the leading end of the trailing rolled material. The clamps are attached in pairs so as to sandwich the contact surfaces between them, and a discharge current of a capacitor bank provided on the power supply side is passed between the pair of power supply clamps.

[0007]

[Operation] The load charged in the capacitor bank is passed through the power supply clamp as a large current to the contact surfaces at both ends in the board width direction to heat them. Then, when the temperature reaches a point where pressure welding is possible, the material is deformed and melted by the pressure of a push-in pinch roll or the like, thereby joining. Note that, for example, the current application time is 0.
．． 1 second or less, the current density is 150A/mm2,
The pressing force can be 2 to 3 kg/mm2, and even if the line running speed is 60 m/min, there is almost no movement of the power supply clamp during the power supply time. If you prepare multiple capacitor banks to increase the energization time, the discharge time can be reduced to 0.
．． It can be done in about 1 second.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to FIGS. 1 to 6. In addition, the same parts as FIGS. 7 and 8 are
The same symbol shall be attached. 1 and 2 mainly show the respective direction surfaces of the preceding rolled material 2 and the succeeding rolled material 1, and represent the shape of the facing surface and the shape of the contact surface 11. Figure 1 (a1) (a2)
In the case of cutting in a straight line, the terminal end of the preceding rolled material (referred to as the leading material) 2 is cut into a concave shape with protrusions at both ends, and the leading end of the trailing rolled material (referred to as the trailing material) 1 is cut into a concave shape with protrusions at both ends. Cut into straight lines and butt them together. FIGS. 1(b1) and 1(b2) show the case of cutting in an arc shape, and this shape can be used even when the rolled material is individually and intermittently rolled. That is, if the shape is arcuate, the impact when biting into the roll is reduced and the life of the roll is extended. Figure 2 (a1) (a2) Preceding material 2
When cutting by changing the radius of curvature between the terminal end of the trailing material 1 and the leading end of the trailing material 1, the structure of the cutting blade can be simplified and roughened. Figure 2 (b1)
In (b2), one side is arcuate and the other side is linear. Both can be used to join materials of different widths.

FIGS. 3 and 4 show a configuration for explaining the current pressure welding method, and FIG. 5 shows the operating principle. In FIG. 3, when the leading material 2 and the trailing material 1 are running on the table roller 9, the pushing roller 10 increases the speed of the trailing material 1 to V2 while the leading material 2 is running at a constant speed V1. It is pressed with a constant load P2. At the same time, the power supply clamp 5 is pressed against the preceding material 2 and the succeeding material 1 from above using a hydraulic (air) cylinder 8. At this time, the pair of power supply clamps 5 are arranged so as to sandwich the opposing surface or the contact surface 11.

[0010] Next, the charging current I1 of the capacitor C connected in the power supply circuit is discharged in a short time, and the leading material 2 and the trailing material 1 are An impact current I2 is applied to the contact surface 11. In this case, capacitor C is charged by turning on switch S1, and discharged by turning on switch S2. When the contact surface 11 is energized, the contact resistance and volume resistance of the contact surface 11 cause the end contact surface 11 in the board width direction to rise in temperature, deform, and melt, and the leading material 2 and the trailing material 1 are connected to the opposing surfaces of the contact surface 11. It is joined at both ends in the field direction. After this, pull up the power supply clamp 5 and switch S1
By turning on the capacitor bank C, the power supply DC starts charging the capacitor bank C. Then, preparation is made for the next joining of the contact surfaces.

FIG. 4 shows a power source that performs long-term discharge and its waveform. The discharge time of a capacitor is determined by the capacitor's capacity and the reactance of the circuit, and cannot be freely controlled. However, as shown in FIG. 4(a), a plurality of capacitor banks C1 to C3 are provided, and these are changed to intervals t1 to t3 by a mixing bridge made up of thyristor switches S2a to S2C. As a result, it becomes possible to control the energization time.

FIG. 5 shows the steps of this embodiment.
) shows a state in which the leading material 2 and the trailing material 1 are separated and the power feeding clamp 5 is not pressed against the steel material, and (b) shows the state in which the trailing material 1 is pressed against the leading material 2 and the power feeding clamp 5 is pressed. It shows the state of being applied, energized, and being bonded, and furthermore, (
c) shows a state in which the power supply clamp 5 remains connected even if it is separated from the steel material. In the state of (a), the switch S1 is closed and the switch S2 is opened, and the speeds V1 and V2 of the leading material 2 and the trailing material 1 have a relationship of V1 < V2. In addition, in (b), switch S1 is opened and switch S2 is closed, and the discharge current flows, but the speed is still V1 < V2.
There is a relationship between Further, in (c), the switches S1 and S2 are in the same state as in (a), and the speed becomes V1 = V2. In addition,(
In b), P1 represents the pressing force of the power supply clamp 5, and P2 represents the pressing force of the preceding material.

[0013] Figure 6 shows the relationship between the current density and current application time required to join rolled materials whose temperature is 900°C.
It turns out that a current density of /mm2 or higher is required.

As an example of practical application, the temperature of the rolled material is 9
In hot rolling at a high temperature of 00°C to 1100°C, using a plate thickness of 20 to 50 mm and a plate width of 700 to 2000 mm,
By setting the contact surfaces at both ends in the width direction of the plate to 1 to 3 times the thickness of the plate, bonding can be suitably achieved in a short time of 5 seconds or less.

[0015] Since the power supply clamp 5 moves together with the rolling material, it is preferable that the power supply clamp 5 is configured to be movable by about 100 mm.

[0016]

[Effects of the Invention] As explained above, according to the present invention, since a large current is passed for a short time by a capacitor at a determined joining location, rolled materials can be joined in a short time and reliably.
Furthermore, it is highly efficient due to direct energization for short periods of time, and requires only a small power supply capacity as it uses a large current generated by discharging the capacitor approximately once per minute. Therefore, the traveling device can be omitted, resulting in a compact device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the end shape of a rolled material.

FIG. 2 is a diagram showing the end shape of rolled materials to be joined.

FIG. 3 is a block diagram for an embodiment of the method of the invention.

FIG. 4 is an explanatory diagram of the magnitude and time of the applied current.

FIG. 5 is a process diagram of the method of this embodiment.

FIG. 6 is a graph showing an example of joining conditions for rolled materials.

FIG. 7 is an explanatory diagram of a conventional joining method.

FIG. 8 is an explanatory diagram of the joint surfaces necessary for rolling and conventional flash butt welding.

[Explanation of symbols]

1 Trailing material 2 Preceding material 4 Roll roll 5 Power supply clamp 7 Current transformer 8 Hydraulic (air) cylinder 9 Table roller 10 Push roller 11 Contact surface 12 Flexible bus bar S1, S2, S2a, S2b, S2c Switch C Capacitor bank

Claims (1)

[Claims] Claim 1: In a continuous rolling line in which the rear end of the preceding rolled material and the leading end of the trailing rolling material are joined together and continuously rolled, the trailing end of the leading rolling material and the leading end of the trailing rolling material are connected. At least one of the surfaces facing the part is processed so that only both ends in the sheet width direction are in contact with each other, and the respective facing surfaces of the rear end of the preceding rolled material and the leading end of the trailing rolled material are processed. The contact surfaces formed at the ends of the two are pressed against each other, and power supply clamps are attached to the rear end of the preceding rolled material and the tip of the trailing rolled material in pairs so as to sandwich the contact surfaces. An impact current pressure welding method for steel plates, characterized in that a discharge current of a capacitor bank provided on the power supply side is passed between the power supply clamps forming the structure.