JP2730704B2 - Connecting the steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting strips using a spot welder, and more particularly, to connecting a tail end of a preceding strip and a tip of a succeeding strip to connect these strips continuously. The present invention relates to a method of connecting a steel strip in a facility for treating wastewater.

[0002]

2. Description of the Related Art In a temper rolling line, for example, instead of batch-processing strip steel coils one by one, continuous processing is performed while sequentially connecting strip steel strips, thereby saving the time and effort of threading. Improving productivity.
In this case, the tail end of the preceding strip and the tip of the succeeding strip are connected by welding.

As such welding methods, there are a flash butt welding method, an arc welding method, a spot welding method and the like. In the case of the flash butt welding method, the equipment becomes large-scale, and the arc welding method requires a long time for welding. There is a disadvantage that requires. Furthermore, in the case of spot welding, the welding machine itself is relatively simple, and there is an advantage that the welding time is short, but since the welding area is significantly smaller than the cross-sectional area of the mother plate,
There is a disadvantage that the strength of the connection part remains uneasy.

In recent years, in particular, due to demand for quality, in order to improve the shape of the steel strip, an entrance bridle roll is installed on the entrance side of the temper rolling mill, and a tension leveler and an exit bridle roll are installed on the exit side. The tempered rolling is performed on products with good shapes under the following conditions. An example is shown in FIG. In the figure, a temper rolling mill 1 temper-rolls a strip S unwound from a strip coil C of a pay-off reel 2, and forms a tension reel 3.
To rewind the coil. The entrance side bridle roll 4 is installed on the entrance side of the temper rolling mill 1, and the tension leveler 5 and the exit side bridle roll 4 'are installed on the exit side. The tension is applied and the shape is corrected by the tension leveler 5.

Here, reference numeral 6 denotes a welding machine, which connects the tail end of the preceding strip and the tip of the succeeding strip by welding. 7,
Reference numeral 7 'denotes a pinch roll on the input side and output side, and reference numerals 8 and 8' denote shears. In such a temper rolling line, the temper rolling is continuously performed by sequentially connecting the steel strip unwound from the steel strip coil to the preceding steel strip as described above. In this case, if a spot welder is used as a welding machine, the strength of the connection portion remains uneasy. As a technique developed as a countermeasure for this, there is a welding method as disclosed in, for example, JP-A-2-25282. This welding method uses a seam welding electrode roll, first performs spot welding of temporary fixing, and then performs seam welding using the same electrode.

[0006]

The welding method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-25282 is advantageous in that the strength of the connecting portion is sufficient and a smooth welded portion can be obtained. And the seam welding process requires two steps, so there is a problem in that the welding time is prolonged. In particular, as shown in FIG. 5, in a line where no looper is installed on the entrance side and the exit side, the time spent for welding is immediately produced. The problem is significant because it affects efficiency.

An object of the present invention is to provide a connection method in which strips are connected to each other using a normal spot welder, and even if the strips are continuously processed under a high tension, welding breakage of the connection does not occur. With the goal.

[0008]

According to the present invention, there is provided a method of connecting a steel strip in a facility for continuously treating a steel strip connected by using a spot welder, the method comprising the steps of: The shape near the tail end of the preceding strip and the vicinity of the tip of the succeeding strip are measured by the shape detector installed on the electrode entry side of the electrode, and the welding spot pitch in the sheet width direction by the spot welder is adjusted based on the measurement results. In this way, the above-mentioned problems of the conventional technique are solved.

[0009]

[Operation] When connecting steel strips by spot welding and continuously processing the steel strips under relatively high tension, the welding at the connection may be broken. Investigation of the strip steel thus broken revealed that there was a shape defect near the connection part due to belly extension or ear extension.

[0010] Fig. 3 shows that the defective shape portion is connected by spot welding.
It is an investigation of the tension distribution in the direction. In this figure, the solid line represents the case of belly extension, and the dotted line represents the case of ear extension.In both cases, the condition immediately before the welding of the connection portion was broken. In this case, it can be seen that the tension is extremely concentrated at the center. And the tension concentration rate α
Can reach nearly three times assuming that the low tension part is 1.

In this case, the steel strip used had a steepness λ = 2%. Here, the steepness λ is λ = | Δh | from the distance d between the two points of the strip S and the height difference Δh as shown in FIG.
(Πd) × 100 (%). Therefore, in the present invention, a shape detector is installed on the electrode entrance side of the spot welder, and the shape near the tail end of the preceding strip and the shape near the tip of the succeeding strip are measured with this shape detector. Based on the results of both shape measurements, a tension distribution in the plate width direction as shown in FIG. 3 is assumed based on the larger steepness. Decide. In this manner, welding having a strength corresponding to the tension distribution in the strip width direction of the strip can be performed, and a connection portion having sufficient strength can be obtained even when a spot welder is used. Of course, in this case, if further fine adjustments are made in consideration of the thickness of the target strip and the processing tension of the line, more ideal welding becomes possible, and welding fracture of the connection portion can be prevented beforehand. Things.

[0012]

FIG. 1 shows an example of a spot welder incorporating a shape detector for carrying out the present invention, and FIG. 2 shows an outline of a procedure for adjusting the welding spot pitch of the spot welder. In FIG. 1, a spot welder 10 has upper and lower electrodes 11, 11 '.
The electrodes 11, 11 'perform spot welding while moving in the width direction of the strip S (in the direction perpendicular to the plane of the drawing) by a driving device (not shown). The steel strip S is indicated by an arrow X.
Proceed in the direction. Reference numeral 12 denotes an entrance clamp, reference numeral 13 denotes an electrode clamp, and reference numeral 20 denotes a plurality of shape detectors mounted on the electrode entrance side of the spot welder, which are installed in the plate width direction.

First, the tail end of the preceding steel strip S ₁ is connected to the shape detector 20.
When passing through the position, the steepness λ _{1 in the} vicinity of the tail end is measured, and thereafter, when the tail end reaches a predetermined position, this is clamped by the exit side clamp 13. Subsequently, the succeeding steel strip S
_When the tip ₂ passes through the position of the shape detector 20, the steepness λ ₂ near the tip is measured, and then when the tip reaches a predetermined position, it is clamped by the entrance clamp 12.

In this state, the tail end of the preceding strip and the tip of the succeeding strip are cut by a rotary shear (not shown), and the tail end and the tip are wrapped in a required amount. , 11 'are moved in the plate width direction to perform spot welding. In this case, the steepness λ _{1 of} the leading end of the preceding strip S ₁ is compared with the steepness λ _{2 of the} leading end of the succeeding band S ₂ ,
The distribution of the tension in the plate width direction is assumed on the basis of the larger one, and the pitch P of the spot welding in each part in the plate width direction is determined. For example, in the case of the antinode stretch shown in FIG.
Welding is performed so as to have a pitch of 1/3 (2.5 to 3 times the number of dots).

One shape detector 20 is provided at the center in the width direction of the steel strip S and one at each end, and each one at both ends is movable so as to correspond to the plate width. It is desirable that the number and functions be determined according to conditions such as the strip width of the steel strip to be processed in the line. next,
The procedure for adjusting the welding spot pitch of the spot welder will be described with reference to FIG. The laser light emitted from the laser light emitting unit 21 of the shape detector 20 is reflected from the surface of the steel strip S, but two reflected lights separated by a predetermined distance d are captured by the light receiving unit 22 and
The height difference Δh between the points is obtained by the signal processing unit 23. Then, the steepness λ is calculated from the measured value and input to the calculator 24. The arithmetic unit 24 compares the measured values of λ of each of the plurality of shape detectors installed in the sheet width direction, and also uses the strip thickness t, the sheet width B, the tension F, and other signals taken from the host computer to obtain the strip steel. The distribution of the tension at the connection portion is predicted, the spot pitch P of spot welding in the plate width direction is calculated based on the predicted pattern of the tension distribution, and this is made to correspond to the plate width direction b. Output to By performing spot welding in this way, an ideal steel strip connection can be obtained.

For example, when a steel strip having a thickness of 2.3 mm and a width of 1200 mm is treated with a unit tension of 6 kgf / mm ² (total tension of 16500 kgf), the steepness λ of the shape at the joint of the steel strip is 2% and the belly elongation is 2%. In this case, the spot welding pitch should be 80 mm between 600 mm in the center of the plate and 30 mm between 300 mm on both ends. In this manner, the temper rolling of the hot-rolled steel strip was performed while adjusting the welding point by the spot welder according to the shape of the connection portion. As a result, welding breakage of the connection portion, which has conventionally occurred three to four times during the month, has hardly occurred.

[0017]

By performing the method of connecting a steel strip according to the present invention, welding can be performed in accordance with the distribution of tension caused by a defective shape, and even when a spot welder is used, the welding of the steel strip can be performed. The economic effect is great, as welding breakage at the connection portion can be prevented beforehand, productivity is not hindered, and a relatively inexpensive and easy-to-operate welding machine can be used.

Further, if the present invention is applied to a hot-rolled strip processing equipment whose shape control is not sufficiently performed, the effect can be further exhibited.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an example of a spot welder incorporating a shape detector to carry out the present invention.

FIG. 2 is an explanatory diagram of a procedure for adjusting a welding spot pitch of a spot welder according to the present invention.

FIG. 3 is an explanatory diagram of a tension distribution generated in a sheet width direction due to a shape defect of a steel strip.

FIG. 4 is an explanatory diagram of a steepness of a defective shape portion.

FIG. 5 is an explanatory diagram of an example of a temper rolling line incorporating a tension leveler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temper rolling mill 2 Payoff reel 3 Tension reel 4 Bridle roll 5 Tension leveler 6 Welding machine 7 Pinch roll 8 Shear 10 Spot welder 11 Electrode 12 Inlet clamp 13 Exit clamp 20 Shape detector 21 Laser emitting part 22 Light receiving part 23 Signal processing unit 24 Computing unit 25 Controller C band steel coil S band steel

 ────────────────────────────────────────────────── (5) Continuation of the front page (56) References JP-A-63-11998 (JP, A) JP-A-4-89179 (JP, A) JP-A-52-2540 (JP, A) JP-A-2- 25282 (JP, A)

Claims (1)

(57) [Claims] 1. A method for connecting strips in a facility for continuously treating strips connected using a spot welder, wherein the strip steel is connected to a lead welder by a shape detector installed on an electrode entrance side of the spot welder. Measuring the shape of the vicinity of the tail end and the vicinity of the leading end of the succeeding strip, and adjusting the welding point pitch in the sheet width direction by the spot welder based on the measurement result to perform welding. .