JPH084804B2 - Chatter mark prevention rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Object of the Invention" The present invention relates to a chatter mark prevention rolling method, and a plate thickness of 0.7 m.
An object of the present invention is to provide a method capable of accurately preventing chatter marks in cold rolling of m or less, stably producing a plate material having a good surface property, and improving yield.

(Industrial application field) Metal rolling technology such as steel plates with a thickness of 0.7 mm or less.

(Prior Art) In cold rolling a thin sheet, conventionally, a small Levers cold rolling mill or the like is used to intermediate the work rolls 2 and 2 for the material 6 to be rolled as shown in FIG. Rolls 3 and 3, guide backup rolls 4 and 4, and center backup roll 5 are arranged and rolling oil is supplied from the coolant nozzles 1 and 1 for rolling. In this case, a large amount of rolling oil is secured. Therefore, the discharge pressure is generally set to 2 kg / cm ² or more.

Incidentally, for example, Japanese Patent Publication No. 61-16522 and Japanese Patent Laid-Open No. 57-156.
The technology related to the prevention of chattering has been announced in Japanese Patent No. 807, but the chattering announced in these publications causes the rolling mill itself to vibrate due to excessive lubrication,
It causes a drastic plate thickness variation in the steel plate, which is completely different from the chatter mark of the present invention. That is, according to the chatter mark of the present invention, vibration of the entry side strip during rolling creates unevenness of lubrication and unevenness of oil pits occurs on the surface of the steel sheet, resulting in a fold-shaped mark. Chattering is a completely different thing because it causes a strong thickness variation in the steel sheet.

(Problems to be Solved by the Invention) In the case of the technique as shown in FIG. 2 of the related art as described above, when the plate thickness becomes small and becomes 0.7 mm or less, particularly 0.4 mm or less, the surface of the plate after rolling is apt to have a wrinkle. A so-called chatter mark occurs.

Therefore, it is difficult to obtain a product having a good surface quality, which is a major cause of a decrease in yield.

"Structure of the Invention" (Means for Solving the Problems) In the case where a rolling machine having a work roll diameter of 120 to 60 mm is used to carry out rolling at an entrance side plate thickness of 0.7 mm or less of a material to be rolled
A chatter mark-preventing rolling method, characterized in that an inlet side (rear) tension is set to 20 kg / mm ² or more and a supply pressure of rolling oil and / or cooling water is set to 0.5 kg / cm ² or less.

(Operation) By using a rolling machine having a work roll diameter of 120 to 60 mm, a thin plate material having a thickness of 0.7 mm or less can be smoothly rolled by a relatively small rolling facility. A work roll diameter of 60 mm or more provides durability against roll wear, and a work roll diameter of 120 mm or less enables rolling under a relatively low load.

Vibration of the material to be rolled is suppressed by setting the inlet (rear) tension of 20 kg / mm ² or more, and the discharge pressure of the rolling oil and cooling water from the coolant nozzle is set to 0.5 kg / cm ² or less. Appropriately prevent vibration of rolled material to avoid chatter marks.

Whether the rolling oil or the cooling water is one or both of them, the discharge pressure can be controlled as described above to prevent the occurrence of chatter marks. The correlation with the amount is also small, and the discharge pressure is controlled to achieve substantially accurate prevention.

The rolling reduction in each rolling pass is generally about 10 to 20%, and the rolling method may be either revers or tandem.

Regarding the plate thickness of the material to be rolled, chatter marks are completely absent when the thickness is 1.0 mm or less, and the occurrence is remarkable when the thickness is 0.7 mm or less, particularly 0.4 mm or less, but in any case by suppressing the vibration as described above. Take effective prevention. In the case of a rolling process that can eliminate chatter marks generated by subsequent passes even when the plate thickness is 0.7 mm or less, the discharge pressure of rolling oil or cooling water can be set to 0.5 kg / cm ² or more.

(Examples) When the present invention as described above is specifically described,
As a result of repeated studies on the prevention of chatter marks commonly referred to as "tatamijiwa" in the prior art as described above, the present inventors do not find chatter marks at least when rolling steel sheet material of 1.0 mm or more. On the other hand, when a thin plate material is rolled with a work roll of 120 to 60 mmφ, chatter marks are more prominent as it becomes thinner. Therefore, in order to prevent the occurrence of such chatter marks, we examined how to increase the tension in the front and back of the work roll and shorten the distance between the work roll and the anti-crimping rolls provided before and after the work roll. However, the former has a risk of sheet breakage especially with respect to an annealed material plate and the like, and the latter is also limited in terms of equipment, and even if it has some effect, it cannot be an effective and accurate solution.

Therefore, after further studying, as a result of the study, it was conceived to reduce the discharge pressure of the rolling oil and / or the cooling water supplied from the coolant nozzle in such thin rolling.
We succeeded in obtaining favorable results. That is, the discharge of rolling oil or cooling water by this coolant nozzle is supplied at a high pressure of ² kg / cm ² or more as described above, but the material to be rolled is made thin by the discharge pressure of such rolling oil or cooling water. It was vibrated considerably, and it was estimated that chatter marks were generated during rolling under such vibration conditions.

A concrete example will be described. In contrast to the conventional mechanism shown in FIG. 2, the work rolls 2, 2 are spaced from each other by 1200 mm as shown in FIG. 2 and the clant nozzles 1 and 1 are provided in the same manner as in FIG. 2 to supply the rolling oil. Further, these anti-crimping rolls 7 and two deflours 8 having a distance of 500 mm with a distance of 1800 mm from the anti-crimping rolls 7 are provided. When the Levers rolling consisting of 6 passes shown in the following Table 1 was carried out on the SPCC rolled material by the rolling stand provided with No.
By rolling from 7mm thickness to 0.283mm, a good thin plate without chatter marks could be obtained. In this case, as the rolling oil, mineral oil 100%, a viscosity of 7 to 8 cst, and a temperature of 30 to 50 ° C. are used, 1 to 5 passes are 0.4 kg / cm ² , and 6 passes are 0.1 kg / c.
Although it was discharged and supplied at m ² , the tension was gradually increased to a tension of 20 kg / mm ² or more in the 4th to 6th passes, and a good product was obtained.

Similarly, for rolling SPCC rolled material (0.7 mm t × 725 mm w) in 6 passes to a thickness of 0.25 mm, a 120 mmφ semi-high speed roll with a roughness of 0.05 μm Ra was used as a work roll. tension increase progressively from the likewise first pass, in the fourth pass the exit-side (front) tension 25 kg / mm ^2, the input (rear) tension 21 kg / mm ^2, the exit side in the fifth pass tension 27 kg / m
m ² , entry side tension 25 kg / mm ² , exit side tension in the 6th (final) pass
The results obtained by rolling at 27 kg and an inlet side tension of 25 kg / mm ² under the conditions shown in the following Table 2 with the same discharge pressure and line speed of the above-mentioned rolling oil from the coolant nozzle are also shown in Table 2. As shown.

However, Fig. 1 shows a summary of these results, in which either or both of the rolling oil and the cooling water by the coolant nozzle are discharged to the final pass and the final pre-pass as 0.5 kg / cm ² or less. It was confirmed that the thin plate material without chatter marks can be appropriately rolled by supplying it.

For the rolled material Nos. 1 to 6, even if the first to fifth passes satisfy the conditions of the present invention, the discharge pressure in the final six passes is
When it is 1.0 kg / cm ² or more, the occurrence of chatter marks cannot be avoided, and in Nos. 11 and 12, even if the sixth pass satisfies the conditions of the present invention, the fifth pass immediately before that. When the condition of the present invention is not satisfied, the chatter mark generated in the fifth pass cannot be erased in the sixth pass, and some chatter mark remains. In addition, in the case of No. 11 and 12, when the discharge pressure in the 5th pass is 0.5 kg / cm ² , a thin plate without chatter marks can be obtained, while in the case of No. 7 and No. 8, When the coolant pressure in the sixth pass was set to 0.6 kg / cm ² , some chatter marks were still observed.

`` Effects of the Invention '' When the present invention as described above, in rolling a thin plate having a thickness of 0.7 mm or less, it is possible to stably produce a thin plate having good surface properties by effectively preventing the occurrence of chatter marks, Since the yield can be improved and disadvantages in the conventional method can be eliminated, the invention is industrially highly effective.

[Brief description of drawings]

The drawings show the technical contents of the present invention. FIG. 1 is a chart summarizing a chatter mark generation state in the relationship between coolant nozzle discharge pressure and line speed, and FIG.
FIG. 3 is an explanatory view showing the constitution of the rolling stand work roll portion, and FIG. 3 is an explanatory view showing the constitutional relation of the rolling stand portion in the embodiment of the present invention. However, in these drawings, 1 is a coolant nozzle,
2 is a work roll, 3 is an intermediate roll, 4 is a side backup roll, 5 is a center backup roll, 6 is a material to be rolled, 7 is an anti-crimping roll, and 8 is a defroll.

Claims (1)

[Claims] 1. When a rolling mill having a work roll diameter of 120 to 60 mm is used to carry out rolling with a plate thickness of 0.7 mm or less on the entry side of the material to be rolled, the entry (rear) tension is set to 20 kg / mm ² or more. A method for preventing chatter marks, characterized in that the supply pressure of rolling oil and / or cooling water is 0.5 kg / cm ² or less.