JPS635803A - Method for detecting welding position of belt-like steel sheet - Google Patents

Abstract

PURPOSE:To surely detect the welding position of belt-like steel sheets without giving ill effects to a product and to permit stable rolling by providing semicircular notches of a prescribed size to both ends of the weld zone of said steel sheets and optically detecting the same. CONSTITUTION:The belt-like steel sheets 1 are butt welded by a welding machine 2 and are formed with the notches 14 at both ends of the weld zone by a notching device 3. The notching depth 17 of the notches 14 is specified to <=10mm of the end cutting width and the notching length 16 is specified to about >=60mm of the moving distance of the steel sheets or above in the response time of a detector. The notches 14 are detected by the optical detector 4 and the steel sheets are rolled by decreasing the steel sheet speed with a control device 6. Since the notches 14 are cut away in the final stage, there is no ill effects to the product and the stable rolling is executed by surely detecting the weld zone.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for detecting a welding position of a steel plate during cold rolling of a strip steel plate.

[Prior art] In cold rolling, as shown in FIG. 3, there is a case where a welded portion 10 of a strip steel plate l between an inlet coil 7 and an outlet coil 8 is rolled in a pickling line in the previous process. many.

In addition, as shown in Figure 4, in a fully continuous rolling mill,
All of the welded parts of the strip steel plate l welded by the welding machine 2 downstream of the inlet coil 7 are rolled by the rolling mill roll 5. 9 in the figure is a looper.

However, since the welds between the steel strips mentioned above often break during rolling due to weld defects, it is necessary to reduce the speed of the steel plates or reduce the tension immediately before the welds enter the rolling mill. Therefore, it is necessary to accurately detect the position of the welded joint of the steel plate before it enters the rolling mill.

The conventional method for detecting the position of a welded joint, as shown in FIG. It was detected by the optical signal it detects.

In addition, in order to detect welds without drilling holes, a method of detecting material non-uniformity in welds using an eddy current flaw detector has also been used, but compared to the punch hole method described above, this method may cause false detection. Since this method is frequently used (accuracy rate is about 80%), the punch hole method described above was generally used.

[The problem that the invention attempts to solve]

When using the above-mentioned punch hole method, the steel plate near the welded part cannot be used as a final product, which naturally causes the problem of lower product yield.In addition, as shown in Figure 6, the punch hole method 11, there is a flaw 1 in the roll 5 of the rolling mill.
3, and this roll flaw 13 is retransferred to the rolled material 13.
In some cases, these roll flaws remain over the entire length of the steel strip 1, resulting in a defective product.

Therefore, the technical object of the present invention is to accurately detect the welding position of a steel plate without using the punch hole method.

[Means to solve the problem] Conventionally? In the tV'ltz tIfA plate welding part, welding defects are likely to occur at the edges at both ends of the plate width, so both edges are cut out into half-moon shapes 14a and 14b, as shown in FIG. 7(a). The presence of this notch means that it cannot be used as a product as it is, and for products with strict quality requirements, it is necessary to remove edge drops and correct flaws and irregularities in the edges as shown in Figure 7 (b). like,
In the final process, both edges are cut along the entire length of the steel plate by an edge cutting allowance 22, and the plate width 20 is made into a product with a product width 21.

Focusing on this fact, the presence of the notch allows the position of the weld to be detected by an optical signal instead of a punch hole, and the notch depth of the edge notch can be determined by the edge notch 22.
If it is made smaller, even if the roll flaws 15a, 15b, 15c, 15d... caused by the notches 14a, 14b are retransferred to the rolled material and remain, they will be within the cutting width and will be cut and removed together with the notches, and the product will be cut and removed. This means that it no longer appears in .

Therefore, the technical means for detecting the welding position taken to solve the technical problems of the present invention are as follows.

(b) Prior to the cold rolling process, at both ends of the welded area where steel strips are welded together, a cut depth that is less than the edge cutting width of the steel plate and a distance that is greater than or equal to the distance traveled by the steel plate in the response time of the detection device is applied. A notch portion having a half-moon shape or an equivalent shape is provided.

(b) Immediately before the rolling process, the notch in the moving steel strip is detected by an optical detection device.

(effect) The above technical means works as follows.

The notches provided at both ends of the width of the welded steel strip have a depth smaller than the edge cutting width of the steel plate, so the cutout of the steel plate is also made by the notch.

The roll flaws transferred to the steel plate are also removed by cutting within the width of the edge cutting performed in the final process.

In addition, the length of the notch is set to be longer than the moving distance of the steel strip within the response time of the optical detection device.
The notch is detected by reliably detecting the optical signal passing through the notch, and thereby the position of the weld is detected.

〔Example〕

Next, an embodiment showing a specific example of the above-mentioned technical means will be described with reference to the drawings.

FIG. 1 shows a system diagram of a cold rolling operation of a steel strip including the present invention, and FIGS. 2(a) and 2(b) are plan views of a notch in a welded portion of a steel plate made by a notching device.

In FIG. 1, the steel strip l unwound from the inlet coil 7 is welded 4212 by flash-hat welding, arc welding, laser beam welding, etc., and the shearing blade of the notching device 3 cuts the welded portion of the steel plate. Both ends of the width
It is sheared into a cutout shape 14 with the hatched portions shown in Figures (a) and (b) removed.

This notch has a cutting depth 17 of 10 mm or less. A board width measuring device is used as the optical detection device 4 for detecting the notch. Board width measuring instruments come in contact and non-contact types, and the non-contact type is used because of its responsiveness and detection accuracy. Since the responsiveness of this equation is 10 milliseconds to 50 milliseconds, when the steel plate moving speed on the entrance side of the rolling mill roll 5 is 200 m/min, the length of the steel plate that moves within the detection time of the responsiveness 10 milliseconds. is 2
00xl/60xlOxlO-3 ==0.03 (m), and the notch length needs to be approximately 30 mm or more, but in this example, the notch length was set to 16 in order to reliably detect the notch. It is set to be 60 mm or more.

In addition, although the measurement accuracy of the plate width is ±1 mm, the edge cutting width (edge cutting width 22) in the final process is 3 to 10 mm on one side, so the cutting depth of the notching device 3 should be adjusted to the edge cutting width 22 or less. There is.

If the plate widths before and after the weld are different, determine the depth of cut based on the narrower plate width.

To explain an example of notch detection, a plate width measuring device adjusted to be equal to the plate width is placed below the steel plate l in the plate width direction,
Provide a light source at both ends or at one end of the measuring device. As the steel plate l moves, when the notch comes above the light source, the light passing through the notch is detected by a phototube, and the notch is detected.

The signal detected by the strip width measuring device 4 is transmitted to the rolling mill control device 6, which reduces the speed of the steel strip entering the rolling mill rolls 5. In the example, the speed is reduced from 200 m/min to 100 m/min.

Although the above embodiments have been described with respect to cold rolling, the method of the present invention can also be applied to temper rolling, etc.

(Effect of the invention) According to the present invention, the following effects are produced.

In order to detect the welding position, the conventional punch hole method detects the punch hole 11 provided in the center of the sheet width, so the punch hole S and the retransfer 13a of the roll flaw caused by the punch hole remain on the product. However, since the notch method of the present invention detects the notches 14a and 14b provided at both ends of the board width, the notches and retransfer of roll scratches 15a and 15b due to the notches are All of them are removed within the cutting width (edge cutting margin), so they do not affect the product, and the product yield is improved.

[Brief explanation of drawings]

Fig. 1 is a system diagram of an embodiment of cold rolling work to explain the present invention in detail, Figs. 2 (a) and (b) are plan views of a notch of a welded part of a steel plate, and Fig. 3 is a diagram of a welded part of a strip steel plate. A perspective view explaining winding, FIG. 4 is a flow sheet of a fully continuous rolling mill, FIG. 5 is an explanatory diagram of a conventional welding position detection method, and FIG. 6 is a perspective view showing roll flaws and retransfer of roll flaws. , FIG. 7(a) is an explanatory diagram showing a notch at the edge of the weld, and FIG. 7(b) is an explanatory diagram showing edge cutting. l... Strip steel plate 2... Welding machine 3... Notching device 4... Optical detection device (plate 4c measurement) 5... Rolling mill roll 6... Rolling mill control device 7... - Input coil 8... Output coil 9... Louver IO... Welding part 11... Punch holes 12a, 12b... Punch hole detector 13... Punch hole roll flaw 13a... Retransfer part 14... Notch parts 15a, 15b, 15c, 15d - Notch part roll flaw retransfer part

Claims (1)

[Scope of Claims] 1. Prior to the cold rolling process, steel strips are welded to each other at both ends of the weld width, and the steel strips are cut at a cutting depth equal to or less than the edge cutting width of the steel strip and at a response time of an optical detection device. A notch having a half-moon shape or an equivalent shape having a notch length equal to or longer than the moving distance is provided, and the notch in the moving steel strip is detected by an optical detection device immediately before the cold rolling process. Features: A method for detecting welding positions on steel strips. 2. The method for detecting the welding position of a steel strip according to claim 1, wherein the depth of the notch is 10 mm or less and the length of the notch is 60 mm or more.