JPS59218213A - Weld zone detecting method of band plate - Google Patents

Abstract

PURPOSE:To prevent a detection omission of a band plate weld zone by comparing a band plate advancing direction distance between each detector of two pieces or more which have obtained a detecting signal, in plural detectors, and a length of a band plate which has run along this distance derived by this detecting signal. CONSTITUTION:When a band plate 1 advances in the L direction, its weld zone 2 passes through detector 12-14 one after another, and the respective signals M1-M3 are generated from each other. On the other hand, a signal processing part 16 always measures a pulse corresponding to a band plate running length from a pulse generator 15, and pulse measured values between the signal M1 and M2, between M2 and M3, between M1 and M3 are measured as n1-n3, respectively. Also, the processing part 16 stores a distance between the detectors 12 and 13, a distance between the detector 13 and 14, and a distance between the detector 12 and 14, as l1, l2, and l3, respectively. In this case, when pulse calculating values corresponding to each distance l1-l3 between each detector are denoted as N1-N3, and an allowable measurement difference of the pulse measured value is denoted as alpha, OR, AND or a decision of majority of A, B and C is decided as a weld zone detecting logic Z by equations I -III.

Description

DETAILED DESCRIPTION OF THE INVENTION 3.1 Field of Industrial Application The present invention relates to a method for detecting a welded part of a strip plate, which prevents false detection and omission of detection.

3.2 In the continuous processing line for conventional strips, the rear end of the strip currently being processed at the front of the line and the tip of the strip to be processed next
M are welded one after another so that the strip can be processed without being thrown into the line, and the front grip bath contact part is cut at the rear of the line to form a coil and send it to the next process. . Therefore, when automating the line, it is required to detect welds.

Conventionally, detection methods for each part have been developed for the above purpose and can be classified as follows.

(b): Drill a hole near the weld and detect this hole optically (applicable to butt welds).

(b): Magnetically detects changes in the composition or structure between the base metal and the weld using eddy currents (applicable to butt welds).

(c): Detect steps or plate thickness changes in welded parts (applicable to overlap welded parts).

In these methods, when the detection sensitivity is increased to prevent failure to detect welds, there is a problem in that flapping due to poor shape of the strip or thorny surface flaws on the strip may be mistakenly detected as welds. Furthermore, in the method (A), if there is a flaw that penetrates the strip, there is a possibility that it may be mistakenly detected as a bath contact part, so the following method F is used to improve reliability. That is, as shown in FIG.
are drilled and detected by optical detectors 8,9.10.11 installed with the same dimensions as the mutual arrangement of the holes. However, according to this method, if the strip is meandering, holes 4, 5, 6
．． 7 cannot pass over the detectors 8, 9, 10, and 11, and there is a possibility that the welded part cannot be detected.

3.3 Purpose of the Invention The present invention provides a method for detecting a welded part of a strip, which prevents false detection due to flapping of the strip or the presence of flaws, and detects a true welded part. It is.

3.4 Structure 1 of the Invention The present invention will be explained in detail with reference to the embodiments shown in FIGS. 2 and 3. FIG. 2 is a front view, and FIG. 3 is a side view. 12,
13.14 is a plurality of welding part detectors 15 installed at a distance in the traveling direction of the strip S and the width direction C of the strip S.
A pulse generator 16 is a signal processing unit that compares the distance between the respective detectors in the traveling direction of the strip and the length of the strip that has traveled this distance. Detectors 12, 13
.

14 may be either the electromagnetic detection method described in (b) above or the method of detecting a step or plate thickness change described in (c) above.

2 and 3, as the strip 1 advances in the direction of travel, its welded portion 2 passes through the detectors 12.13.14 one after another, and from the detectors 12.13.14 to the fourth Signals Ml, M2 . M3 occurs. On the other hand, the signal processing section 16 constantly measures pulses from the pulse generator 15 corresponding to the traveling length of the strip, and the signal M1 in FIG.
The pulse measurement values between N2 and N2, between N2 and N3, and between M1 and N3 are respectively n 1 r n 2 + n
Measure as 3. The signal processing section 16 also includes a detector 1.
The distance between 2 and detector 13 is 111 detector 13 and detector 14
The distance between the detectors 12 and 14 is t2, and the distance r between the detectors 12 and 14 is V'T.
1 is stored as t3. Here, the pulse measurement values corresponding to the distances t1 rz, l t3 in the strip traveling direction between each detector are N1. N2. When the allowable measurement error of the pulse measurement value is α, the time when the condition n-1=N:1±α is satisfied is An2=N2, and the time when the condition α is satisfied is Bn.
3 = N The time when the condition of 3±α is satisfied is C, and A
, B, and C, the logical sum, logical product, or majority decision is taken as the welding part detection logic 2. FIG. 5 shows the configuration of the signal processing section.

In FIG. 5, ON signals M1. from detectors 12, 13.14. M2. M3 is Noritsubu flop 17°18.19
As a result, the gate 20.21.22 opens and the pulses from the pulse generator 15 are stored in the counter 23.2.
4. Measure according to 25.

Comparison circuits 26, 27, 28 are counters 23, 24°2
5 measurement values nl, n2+n3 and the number of pulses Nl, N2.5 corresponding to the distance between each detector. N3 is compared and the result is output to the logic determining section 30. The logic determination section 30 is the logic setting section 29
It is determined based on the weld detection logic set in , and if the condition is met, it is recognized as a weld and output. In Figure 5, r is a reset signal, SP is a stop signal, and r/st is a reset/st signal.
Indicates a start signal.

The above embodiment is an example in which three detectors are used, but when two detectors are used, the distance between the rain detectors and the length of the strip traveling the distance determined by the detection signal of the rain detectors are determined. It can also be determined that the weld has passed when the two match. Furthermore, if four or more detectors are used, the accuracy will be further improved.

3.5 Effects of the Invention As described above, according to the present invention, the detection signal of each detector due to noise generated at the same timing due to fluttering of the strip or holes passing sporadically is determined by the distance between the detected detectors. This makes it possible to detect only true welds, which enables automation in continuous steel strip processing lines.

[Brief Description of the Drawings] Fig. 1 is a diagram showing an example of a device using a drilling/optical detection method according to the prior art, Figs. 2 to 5 are diagrams showing an embodiment of the present invention, and Fig. 4 is a diagram showing each detection method. FIG. 5 is a block diagram of the signal processing section 8i. l: Strip plate, 2: Strip plate welded part, 4.5.6.7: Hole, 8
．． 9.10,11: Optical detector, 12,13,14
: Detector, 15: Pulse generator for detecting strip running length, 16: Signal processing section, 17.18.19: Flip-flop, 20.21, 22: Gate, 23, 24, 2
5: Counter, 26.27.28: Comparison circuit, 29:
Setting unit, 30: logic determining unit. Applicant: Nippon Steel Corporation Representative Patent Attorney Minoru Aoyagi @ Figure 2 (I) /L Nizu〉 Figure 4! 5 jMj 5

Claims (1)

[Claims] A plurality of detectors of the welded part of the strip are provided at different positions in the traveling direction of the strip and the width direction of the strip, and the strip traveling direction between two or more detectors that obtain detection signals among the plurality of detectors. distance and
A method for detecting a welded part of a strip, comprising comparing the length of the strip that has traveled the distance determined by the detection signal.