JPS58149123A - Steel strip welding position detecting method - Google Patents

Abstract

PURPOSE:To detect the welding portion reliably without sacrifice of the quality of the steel strip, by applying a hot marking agent quickly dryable and burnable by the holding heat on the steel strip welding portion then detecting the coating portion by means of an optical detector. CONSTITUTION:In the manufacture line of the welded H shape steel, the trailing edge of a prior steel strip A rewidened by an uncoiler 11 is welded to the leading edge of a later steel strip by a welder 12, then the excessively welded portion is removed by a remover 13 and a hot marking agent quickly dryable and burnable by the holding heat of the welder is applied on the welded portion by means of a marking device arranged near to said remover 13. Here said welded portion is detected by a light emitter provided at IN-side of a high frequency welder and an optical detector 19 equipped with a light receiver. With this method, the welded portion can be detected reliably without sacrifice of the quality of the steel strip.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for welding a welded connection in a band in which the trailing end of a leading** and the leading end of a trailing steel strip are connected in advance to perform continuous work in a continuous steel strip processing process. The present invention relates to a method for detecting the position of a part.

For example, in a welded H-shaped steel production line, continuous operation is performed by rounding the same work efficiency and yield, and welding the trailing end of the leading steel strip and the leading end of the trailing temperate zone using a welding machine. However, the connection welded part (hereinafter simply referred to as the welded part), except for a part, does not become a finished product and is cut and removed after forming. Various methods have been devised and adopted for this purpose.

For example, Figure 1 is a schematic diagram of an inspection device using a low-frequency magnetic field method. A detection spatula (3) containing a receiving carp A/(2),
*The control unit (4) is connected to the coil +1) +21 to detect the output balance, and the welding g(s)
The composition change in the welded part (B) and the detection head (3)
The position of the welded part (B) is detected by detecting the disturbance of the magnetic field by the relative distance change between the welded parts (B).

However, when detecting a welded portion using such a low frequency magnetic field method, there is a drawback that there are many errors due to the shape and condition of the surface of the LS body, resulting in a lack of reliability.

Further, FIG. 2 is a schematic explanatory diagram showing another detection method, the punch-hole left method. In this method, a hole (5) of about 10 diameters is pre-drilled at the weld zone (B) or just near it, and the hole (6) is drilled at a predetermined position in which the steel strip is conveyed. Place the photocell (6) in the smokehouse.

The copper band welded portion CB) is detected by receiving the light emitted from the phototube (6) through the hole (5) on the light receiving side.

However, since this punch hole method requires drilling holes at 41111, this part cannot be commercialized, and accurate detection cannot be performed due to misalignment between the punched hole and the photocell stage, resulting in waste. However, there were many disadvantages such as lack of reliability.

The present invention has been made to solve the above-mentioned conventional drawbacks, and after applying a hot marking agent that can quickly dry and bake with the heat retained on the welded part of the copper strip, at a predetermined position on the side of the cutting machine line σ, By detecting the 1iJfflE coated area with an optical detector, it is possible to provide a method that can reliably detect this welded area without impairing the quality of the Wi band.

Below, the present invention is applied to the me line of the welding H type.
This will be explained based on one example.

FIG. 6 is a schematic diagram showing a welded H-type production line, in which the rear end of the leading steel strip (A) that has been rewound by the uncoiler (B) and the tip of the trailing steel strip are connected by a welding machine ( After connecting with the remover (to) and removing the remaining part with the remover (to),
The marking device is placed in close proximity to #, and the heat it retains after contact dries quickly and causes burn-in! Apply a suitable hot marking agent to the weld. As the hot marking agent, for example, a marking agent of a water dispersion type paint (trade name: Tynet 1 Coat I) is applied.

The coating size is preferably at least 20 hit times the length; if the coating length is less than 20 cm, it will be difficult to detect using the optical method described below.

On the other hand, the hot marking agent has a temperature of 250°C at the welding part.
If the temperature is less than 1,000 yen, drying will not occur instantly, and the applied area will become unclear when transferred to subsequent bottles, rolls, etc., and the marking agent will adhere to areas other than the welded area, which is undesirable. It is preferable to carry out immediately after welding.

! [Figure 4 shows an example of the time after welding and the temperature distribution of the welded part of a 4.5-〇 steel strip with a plate thickness of 3.2 mgm.

As can be seen from the figure, it is preferable to carry out the weld within about 45 seconds in order to maintain the temperature of the welded part at 250° C. or higher and to coat a length of 20 cm or more.

After the hot marking agent is applied to the welded part in this manner, the band body is formed into an H-beam steel by a high-frequency welding machine A through a pinch row V (b) and a looper (c).

At this time, the welded portion is detected by an optical detector equipped with a light emitter and a light receiver provided on the inlet side of the high frequency welding machine. The optical detector (b) converts the change in the amount of light received due to the difference in color between the surface of the copper strip and the coated area into a change in potential, and detects the marking area, that is, the welded area of the steel strip.

Figure 5 shows that 65 seconds after welding a steel strip with a plate thickness of 3.5 mm and a plate width of 250 cm, a hot marking agent (trade name: Tynetsu 11, white) containing several moisture particles was applied to the steel strip with a hit length of 20 cm. Pinch row y shown in No. 311 after being applied to
An electric FEN of approximately 1°5V was detected in the non-coated area (@ band). The detection signal of the detected value obtained in this way and the time when the welded part reaches the cutting machine (b) K, tTI! After inputting I (calculated based on the feed rate d and the distance between the detector (b) and the cutting machine (b)) to the control device f (not shown), a cutting command is output to the cutting machine αη after a predetermined time. This removes the welded parts.

As explained above, according to the method of the present invention, after a hot marking agent is applied to a welded part, a photoelectric detector is used to convert the received light due to the color #l change between the entire area and the marking part into electric potential. There is no malfunction like in the conventional rounding method, and it is now possible to detect welds without damaging the quality of the steel strip.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional temperate weld detection device using a low shoulder wave magnetic field method, Fig. 2 is a schematic diagram of a steel strip weld detection device using a conventional bunch-hole method, and Fig. 3 is a schematic diagram of a steel strip weld detection device using the conventional bunch-hole method. Figure 1114 is a graph showing the relationship between time and temperature distribution after 'a zone welding, and Figure 115 is a schematic diagram of a welded H-beam steel production line using the four methods of the present invention. 2 is a graph showing potential changes between a welded part and one band, showing an example of the above. ((trans) is - band, (to) is optical detector.

Claims (1)

[Claims] (1) In a method for detecting the position of a welded joint of steel strips connected for continuous operation in a continuous processing process of copper strips, the welded joint is coated with gold, an instant-drying paint that can be baked, and then
A method for detecting the position of a welded joint of a steel strip, comprising detecting the coated part with an optical detector at a predetermined position in front of a cutting machine.