JPH1015781A - Cutting failure part detecting method for metal band cross direction end part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cutting width of a metal band end part by determining a cutting failure part according to the change of a load current value of a cutting edge driving motor. SOLUTION: When cutting edges 4, 4a are driven by driving motors 5, 5a to cut a cut width of a steel band 1 end part, the cutting edges 4, 4a do not come into contact with the steel band 1 end part in a position of a recessed part, there is no contact resistance of the cutting edges 4, 4a, and at this time, the load current values of the driving motors 5, 5a are lowered as compared with the load current values of the driving motors 5, 5a at the time of cutting. The changes of the load current values are detected by a load current value detecting device 7, and for example, a detection signal on the load current value change is introduced into a computer 12 to determine a threshold value of a cutting failure part such as whether it leads to welding failure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a defective cutting portion at an end in the width direction of a metal band.

[0002]

2. Description of the Related Art For example, as shown in FIG. 4, a hot-rolled steel strip (metal strip) as a material for an electric resistance welded steel pipe is formed by cutting an end 2 in a width direction of a steel strip 1 and then forming the steel strip. Next, the smoothed both ends are joined by electric resistance welding to form a continuous pipe, and then cut into a predetermined size (length).

[0003]

As described above, the removal of the end of the hot-rolled steel strip (metal strip) has a disadvantage that the cut amount (width) is large and the yield is remarkably reduced. In addition, since the amount of cutting increases, the life of the cutting blade is shortened, and the number of line stops due to replacement of the cutting blade increases (longens), thereby reducing productivity and increasing the cost of the cutting blade. There is. The method of the present invention has been made in order to advantageously solve such problems. In order to solve the above problems by reducing the cutting width (amount) of the end portion of the metal band, for example, the cause of poor welding is considered. Cutting part (metal band edge)
The large recessed portion accurately detects the occurrence of a poorly cut part (uncut part), thereby reducing the cutting width at the end of the metal band, preventing the shipment of products with poorly welded parts and improving the yield, etc. It is an object of the present invention to provide a method for detecting a defective cutting portion that can perform cutting.

[0004]

A feature of the method of the present invention is that a defective cutting portion is determined on the basis of a change in the load current value of a cutting blade drive motor. This is a method for detecting a defective cutting portion.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, as a cutting portion for detecting a defective cutting portion at an end of a steel strip (metal strip), as shown in FIG. As shown in the drawing, when the cutting width is reduced to cut the ear protrusions of the end 2, depending on the steel strip 1, some of the ear recesses are larger (deeper) than the other recesses. After cutting the convex portion, this portion remains as a concave portion and becomes a defective cutting portion 3a. Even if the both ends of the steel strip 1 are formed after the steel strip 1 is formed, the poorly cut part 3a cannot be bonded to the poorly cut part 3a.

In view of the above, in the method of the present invention, the above-described defective cutting portion 3a is detected based on a change in the load current value of the motor that drives the cutting blade. That is, when the cutting blade is driven (rotated) by the drive motor and the cutting width of the end portion 2 (both ends) of the steel strip 1 is cut, compared with the load current value of the drive motor at the time of cutting, the position of the steel strip 1 The cutting blade does not contact one end, and there is no contact (cutting) resistance of the cutting blade, and the load current value of the drive motor at this time is low. By detecting a change in the load current value, for example, a detection signal of the change in the load current value is introduced into the computer, and a threshold value of the defective cutting portion 3a is determined, for example, as to whether or not the welding leads to defective welding.
In the case of the defective cutting part 3a leading to poor welding, the position of the cutting device and the cutting position after pipe forming (the position where the defective cutting part 3a occurs)
Command the cutting timing of the poorly cut portion 3a (poorly welded portion) after pipe making to the computer of the cutting device from the distance and threading speed of the cutting device, and cut the poorly welded portion when the poorly welded portion reaches the cutting device. is there.

When the defective cutting portion 3a is determined, the load current value varies depending on the type of the cutting steel strip 1 (metal strip), the output of the cutting blade drive motor, the plate thickness, and the like. In the hot rolled steel strip 1 of the material for the electric resistance welded steel pipe, the cutting blade drive motor output is 200 kW.
In the case of, the appropriate range of the plate thickness during cutting and the load current value of the cutting blade drive motor is as shown in FIG.
When the concave portion 3 passes through the cutting blade, the load current value falls outside the appropriate range. Such an appropriate range of the load current value is stored in the computer in advance,
When a change in the load current value of the cutting blade drive motor occurs, the threshold value of the defective cutting portion 3a can be determined. Usually, in the production of an electric resistance welded steel pipe, the steel type (hot-rolled steel strip) is almost constant, and it is sufficient to set an appropriate range of the sheet thickness and the load current value.

In the case where the metal band type other than the cutting metal band, the cutting blade drive motor output, and the plate thickness are different as described above, for example, an appropriate range of the plate thickness and the load current value of the cutting blade drive motor is determined experimentally. By storing the information in the computer in advance, it is possible to reliably detect a defective cutting portion. Also, when there is no significant variation in the type and thickness of the metal band and the end of the metal band is almost constant, there is no appropriate range of the plate thickness and the load current value of the cutting blade drive motor as described above. Then, as described above, the threshold value of the defective cutting portion and the like are determined based on a constant change in the cutting blade drive motor load current value.

In this manner, the defective cutting portion can be accurately grasped by detecting the load current value of the cutting blade drive motor, so that the cutting width (amount) can be reduced when cutting the end portion of the metal band. The yield can be improved and the life of the cutting blade can be extended. In other words, compared to the reduction in yield due to the occurrence of defective cutting portions (poor welding) by reducing the cutting width, the effect of improving the yield by reducing the cutting width and improving the productivity by extending the life of the cutting blade is large, and therefore, By reducing the cutting width, a reduction in yield due to the occurrence of defective cutting (poor welding) is compensated for, and a great effect exceeding the reduction in yield can be obtained.

[0010]

Next, examples of the method of the present invention will be described. In FIG. 1, both ends of a hot-rolled steel strip 1 are passed through cutting blades (milling cutters) 4 and 4a as materials for a medium-diameter electric resistance welded steel pipe, and the cutting blades 4 and 4a are driven by cutting blade drive motors 5 and 5a. When rotating and cutting continuously, the load current value of the cutting blade drive motors 5 and 5a is detected by the load current detector 6, and the value is always guided to the computer 7 and the monitor 9 of the display panel 8. When the cutting blades 4 and 4a do not cut in the concave portion at the end of the steel strip 1 and a cutting defect occurs, and the load current value of the cutting blade drive motors 5 and 5a changes, the steel strip stored in advance in the computer 7 is used. The threshold value of the defective cutting part is determined from the appropriate range of the plate thickness and the load current value of No. 1, and when it is determined that the defective cutting part is present, the distance between the position of the cutting device (not shown) after the pipe forming and the defective cutting part position and At the same time as inputting the timing of cutting by the cutting device from the threading speed to the host computer 10, it also inputs to the alarm device 11 of the display panel 8 to inform the operator, and from the host computer 10 to the computer 12 of the cutting device after pipe making. The above cutting timing is introduced to cut and remove a poorly welded portion (poorly cut portion) after pipe making reaches the cutting device position.

Next, operation examples according to the method of the present invention will be described together with comparative examples. Operation example 1) Metal strip: hot-rolled steel strip, sheet thickness 9.0 mm, sheet width 756 m
m. 2) Cutting width: 6 mm at both ends in the width direction (3 mm on one side, 750 mm width after cutting). After cutting both ends of the hot-rolled steel strip in this way, when the pipes were continuously formed by electric resistance welding, the cutting removal due to poor cutting (poor welding) per 10,000 m of pipe forming was limited to 2 m. The pipe production yield of the belt was 99.0%, and the replacement of the cutting blade due to wear was replaced by cutting at 30 km. Comparative Example 1) Metal strip: hot-rolled steel strip, sheet thickness 9.0 mm, sheet width 762 m
m. 2) Cutting width: 12 mm at both ends in the width direction (6 mm on one side, plate width after cutting 750 mm). After cutting both ends of the hot-rolled steel strip with a large cutting width (amount) so as to prevent the occurrence of a defective portion in this way, and continuously forming the pipe by ERW, the poor cutting per 10,000 m of the pipe was formed. Defect removal was 0 m, pipe yield for hot-rolled steel strip was 96.7%, and cutting blade replacement due to wear was replaced by 20 km cutting.

[0012]

According to the method of the present invention, the cutting width (amount) of the metal band walking can be reduced, and the yield can be improved. In addition, the life of the cutting blade can be significantly extended,
It is possible to reduce the decrease in productivity due to the stop of the line due to the replacement of the cutting blade. Further, excellent effects such as a reduction in the cost of the cutting blade can be obtained.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the method of the present invention.

FIG. 2 is a table showing a relationship between a load current value of a cutting blade drive motor and a metal strip thickness.

FIG. 3 is a plan view showing a cutting width at an end in a metal band width direction.

FIG. 4 is a plan view showing a cutting width at an end in a metal band width direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal strip 4 Cutting blade 4a Cutting blade 5 Cutting blade drive motor 5a Cutting blade drive motor 6 Load current value detector 7 Computer 10 Host computer 12 Computer

Claims (2)

[Claims] 1. A method for detecting a defective cutting portion at an end in a width direction of a metal band, wherein a defective cutting portion is determined based on a change in a load current value of a cutting blade drive motor. 2. The method according to claim 1, wherein an appropriate range of the load current value is set based on the thickness of the metal strip.