JPH07121403B2 - Method for polishing pinch roll for hot rolled steel strip winder - Google Patents

Description

The present invention relates to a method for polishing a pinch roll for a hot-rolled steel strip winder.

[Conventional technology]

As a polisher for pinch rolls for hot rolled steel strip winders,
As a device capable of removing flaws from pinch rolls during a short time between rollings, "Roll polisher for upper pinch rolls" has been proposed in Japanese Utility Model Publication No. 57-116303, but rolling pinch rolls ( It is not yet developed as a technique that can be used during polishing. Therefore, when the tip of the steel strip to be wound collides with the pinch roll guide, the burrs at the tip of the steel strip make a burn mark on the pinch roll surface when it is bitten, and transfer the flaw to the subsequent steel strip. Was occurring frequently.

[Problems to be solved by the invention]

The reason why polishing is difficult during rolling (winding) is as follows.

(B) If polishing is performed during rolling (winding), the resistance against pinch roll rotation is large during polishing, and the rotation speed decreases as much as about 50% of the rated load of the pinch roll drive motor, causing the rotation speed to decrease during winding. In that case, tension is lost between the finish rolling mill and the pinch roll, and a loop is formed, which prevents normal winding. (B) Therefore, if the polishing ability of the polisher is reduced (the pressing force is reduced) to reduce the load on the pinch roll driving motor, it becomes impossible to remove the flaws formed on the pinch roll.

This phenomenon will be explained in more detail with reference to Figs.
When seizure flaws or scratches were generated on the pinch rolls 5 and 6, they were manually removed by polishing with a grindstone. Polisher devices 8 and 9 have been devised to save this effort, but the resistance to pinch roll rotation during polishing is large, and the pinch roll drive motor may reach 50% of the rated load. When it is lowered, the pinch rolls 5 and 6 come into contact with the steel strip 1, and the finish rolling mill 2
The tension between the pinch rolls 5 and 6 disappears and a loop occurs, making normal winding impossible. Conversely, if the polisher polishing ability is reduced and the load on the pinch roll motor is reduced, it becomes impossible to remove the flaw 11 generated on the pinch rolls 5 and 6. Therefore, the polisher polishing is performed during idling other than during winding. According to this method, continuous occurrence of the pinch roll flaws 11 can be prevented, but the pinch roll flaws cannot be completely prevented. Moreover, since most of the pinch roll flaws 11 are caused by the burrs 12 generated when the leading edge 1a of the steel strip collides with the guide guide 10, the flaws 13 are generated over the entire length of the coil.

An object of the present invention is to provide a novel polishing method for performing pinch roll polishing during rolling (winding), and to eliminate a steel strip roll defect caused by a pinch roll.

[Means for solving problems]

The present invention, in the hot rolling of the steel strip, until the tip of the steel strip that has exited the finish rolling mill bites into the pinch roll for the winder until it reaches the winder after passing through the pinch roll from immediately before or immediately before it reaches the winder. A method for polishing a pinch roll for a hot-rolled steel strip winding machine, which comprises polishing the pinch roll by a polisher mounted on the roll. The polishing may be performed by the polisher and the upper pinch roll may be pulled up to the upper portion of the steel strip to continue the polishing even during winding.

[Work]

The present inventors have made various studies on pinch roll polishing during rolling (winding), and at the end of the steel strip exiting the finish rolling machine, the traveling speed is slow at first and the peripheral speed of the pinch roll is better at that stage. Since the rotation speed of the pinch roll was low when the polishing was performed by pressing with a polisher, the loop speed did not occur between the finish rolling mill and the pinch roll. If so, the tip of the steel strip exiting the finish rolling machine will cause seizure on the pinch roll.If the flaw on the pinch roll surface is polished in the early stage of winding, the pinch roll flaw will be formed on the subsequent steel strip. Transcription does not occur.

〔Example〕

1 (a) and 1 (b) show an embodiment of the present invention. First, before the steel strip 1 bites into the pinch rolls 5 and 6, the polishers 8 and 9 are kept in contact with and polished in the pinch rolls 5 and 6 (FIG. 1 (a)). Next, the tip 1a of the steel strip bites into the pinch rolls 5 and 6, and foreign substances that stick to the pinch rolls 5 and 6 at that time are removed by the polishers 8 and 9. At this time, since the pinch rolls 5 and 6 are rotating at a speed higher than the steel strip threading speed, even if the peripheral speed of the pinch rolls becomes low by polishing with the polishers 8 and 9, the rolling mill 2 and the pinch rolls 5 , 6
A loop does not occur between them and normal winding is possible (1st
Figure (b)). The polishers 8 and 9 are separated from the pinch rolls 5 and 6 at the timing when the steel strip tip 1a reaches the mandrel 7, and interrupt the polishing.

If the polishers 8 and 9 are applied during winding, the load on the pinch rolls 5 and 6 will increase, as described above, but this will cause a problem. If the upper pinch roll 5 is pulled up from the steel strip 1 after being wound around the winder and the upper pinch roll 5 is driven and polished at the elevated position, it is possible to perform more complete polishing without the above problems. Is.

Hereinafter, a construction example of the present invention will be described.

For the finisher hot strip mill post-down coiler type winder pinch rolls (rolls hardened on forged steel, upper roll 920mmφ, lower roll 460mmφ)
As a result of carrying out the present invention under the following conditions, the defect occurrence rate (ratio of the number of coils) was 0.2%.

Conditions: 10,000 hot coils (174,000 tons) Elastic grindstone Polisher pressing surface pressure 1.6 kg / cm ² Polishing time 0.5 sec / coil On the other hand, the one polished between the conventional rolling and The defect occurrence rate was 2% under almost the same conditions. Therefore, it can be seen that the present invention reduces the defect occurrence rate by 1.8%.

〔The invention's effect〕

According to the present invention, since the flaw can be removed immediately after the occurrence of the pinch roll flaw, there is an effect that the pinch roll flaw is not transferred to the rolled steel strip and the production yield is improved.

[Brief description of drawings]

1 (a) and 1 (b) are schematic side views for explaining an embodiment of the present invention, FIG. 2 is a schematic side view showing the positional relationship between a hot strip mill, a pinch roll and a winder, and FIG. An explanatory view of the pinch roll and the pinch roll polisher, and FIGS. 4 (a) and 4 (b) are side views for explaining the occurrence state of the pinch roll flaw. 1 ... Rolled material (steel strip), 2 ... Finishing rolling mill, 3 ... Runout table, 4 ... Side guide, 5,6 ... Pinch roll, 7 ... Mandrel, 8,9 ... Pollisher, 10 …
… Guidance guide, 11 …… Pinch roll flaw, 12 …… Steel strip burrs, 13 …… Pushing flaw

Claims (1)

[Claims] 1. In hot rolling of a steel strip, until the tip of the steel strip exiting the finish rolling mill bites into a pinch roll for a winder or immediately before it reaches the winder after passing through the pinch roll. A method for polishing a pinch roll for a hot-rolled steel strip winder, which comprises polishing the pinch roll with a polisher mounted on the pinch roll.