JPH0452003A - Rolling method for preventing chatter mark - Google Patents

Abstract

PURPOSE:To prevent the generation of chatter mark by taking the tension on the inlet side as not less than a specified value and taking the supply pressure of rolling oil and/or cooling water as not more than a specified values at the time of execution of rolling for making the thickness of material to be rolled on the inlet side not more than a specified value using a rolling mill with the specified diameter of work rolls. CONSTITUTION:In the case the rolling for making the thickness of the material to be rolled on the inlet side <=0.7mm using the rolling mill of which the diameter of work roll is 60-120mm, the tension on the inlet side (behind) is taken as >=20kg/mm<2> and also the supply pressure of rolling oil and/or cooling water is taken as <=0.5kg/cm<2>. By taking the tension on inlet side (behind) as >=20kg/mm<2>, the vibration of material to be rolled is restrained. By the discharge pressure of rolling oil and cooling water with coolant nozzle as <=0.5kg/cm<2>, the above-mentioned vibration of material to be rolled is suitably prevented and the generation of chatter mark is surely avoided. In this way, the sheet excellent in surface properties is stably manufactured and its yield can be improved.

Description

Detailed Description of the Invention "Object of the Invention" The present invention relates to a chatter mark prevention rolling method,
It is an object of the present invention to provide a method that can accurately prevent the occurrence of chatter marks during cold rolling of 0 or less, stably produce plate materials with good surface properties, and improve yield.

(Industrial application field) Metal rolling technology for steel plates etc. with a plate thickness of 0.7** or less.

(Prior Art) When cold rolling a thin plate, conventionally, a small lever cold rolling mill or the like is used to roll a work roll 2. A roll 3.3, a guide Hanoku asofluor roll 4.4, and a center hack up roll 5 are arranged, and rolling oil is supplied from coolant nozzles 1 and 1 for rolling. In order to ensure this, the discharge pressure is generally set to 2 kg/cI]1 or more.

(Problems to be Solved by the Invention) In the case of the conventional technology as described above, when the thickness of the plate becomes small, and is less than 0.7 fl, especially less than 0.4 fl, the surface of the plate after rolling is called tatami wrinkles. Chatter marks occur.

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

"Structure of the Invention" (Means for Solving the Problems) When rolling a material to be rolled with an entry side plate thickness of 0.7fi or less using a rolling mill with a work roll diameter of 120 to 601 m, the entry side (backward) The tension is 20 kg/f12 or more and the supply pressure of rolling oil and/or cooling water is 0.5
A chatter mark prevention rolling method characterized in that the rolling amount is less than kg/ctA.

(Function) By using a rolling mill with a work roll diameter of 120 to 60 mm, a thin plate material with a thickness of 0.7 nm or less can be rolled smoothly with a relatively small rolling equipment. The work roll diameter is 60 m or more to ensure durability against roll wear, and the work roll diameter is 120 m or more.
Rolling with a relatively low load is possible by setting it to n or less.

Vibration of the rolled material is suppressed by setting the entry side (rear) tension to 29 kg/w" or more, and the discharge pressure from the coolant nozzle of rolling oil and cooling water is reduced to 0.5 kg/CI.
By setting it to A or less, vibration of the rolled material can be appropriately prevented and chatter marks can be accurately avoided.

By controlling the discharge pressure of either or both of the rolling oil and cooling water as described above, chatter marks can be prevented from occurring.In other words, the viscosity and other factors are not affected much, and the supply The correlation with the amount is also small, and by controlling the discharge pressure, approximately accurate prevention can be achieved.

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

Regarding the thickness of the rolled material, see 1. At 0mm or more, there is no chatter mark, and at 0.7n or less, especially at 0.
．． Although the occurrence is significant below 4n, effective prevention can be achieved by suppressing the vibration as described above. In the case of a rolling process that can eliminate chatter marks caused by subsequent passes even if the plate thickness is 0.7 nm or less, the discharge pressure of rolling oil or cooling water should be set to 0.5 kg.
/cf or more.

(Example) To specifically explain the present invention as described above, the present inventors have repeatedly studied the prevention of chatter marks, commonly known as tatami wrinkles, in the conventional technology as described above, and have found that at least While no chatter marks are observed when rolling a steel sheet with a hardness of 1.0 mm or more, when a thinner sheet is rolled with a work roll of 120 to 601 mφ, the thinner the sheet, the more pronounced the occurrence of chatter marks. Therefore, in order to prevent the occurrence of such chatter marks, we considered increasing the tension at the front and rear of the work roll and shortening the distance between the work roll and the anti-crimping (wrinkle prevention) rolls installed before and after the work roll. However, the former poses a risk of breakage, especially when it comes to annealed material plates, and the latter also has equipment limitations, so even if it has some effects, it cannot be an effective and accurate solution.

After further investigation, we came up with the idea of reducing the discharge pressure of rolling oil and/or cooling water supplied from the coolant nozzle during thin plate rolling, and as a result of our investigation, we succeeded in obtaining favorable results. That is, the amount of rolling oil or cooling water discharged by this coolant nozzle is 2 kg/co!, as mentioned above! Although the rolling oil or cooling water is supplied at a high pressure, the discharge pressure of the rolling oil or cooling water causes the thin rolled material to vibrate considerably, and chatter marks occur during rolling under such vibration conditions. It was estimated that

To explain a specific example, a work roll 2.2 as shown in FIG. 3 is used for the mechanism shown in FIG.
Anti-crimping rolls 7.7 are provided before and after the anti-crimping rolls 7.7 with an interval of 1200 ms from the anti-crimping rolls 7.7.
When 5 pcc of rolled material was subjected to reverse rolling consisting of 6 passes shown in Table 1 below using a rolling stand equipped with two defrolls 8.8 mm apart, the following results were obtained:
From 0.7n thickness to 0.7n thickness. ．． It was possible to obtain a good thin plate with no chatter marks by rolling to 283vm. In this case, the rolling oil is 100% mineral oil and has a viscosity of 7 to 7.
8cst, 30-50℃, 1-5 baths at 0
．． 4kg/cfll, 6 buses at 0.1kg/cn! The tension was gradually increased to 20 kg/m'' or more in the fourth to sixth baths, and a good product was obtained.

The results were conducted under the same conditions as in Table 1, with the discharge pressure and line speed of the rolling oil as shown in Table 2 below.

Table 2: Same <5 pcc rolled material <0.7 mt X725
wmw) to a thickness of 0.25 m in 6 passes, a semi-milled chair roll with a diameter of 120 fiφ and a roll roughness of 0.05 μm Ra was used as a work roll.
, the rolling tension was gradually increased from the first pass in the same way as above, and the rolling tension was gradually increased from the first pass.
In the bus, the tension on the exit side (front) is 25 kg/mm2, the tension on the entry side (rear) is 21 kg/f12, and the tension on the exit side is 27 at the 5th nozzle.
kg/vna2, entry tension 25kg/llm2, exit tension 27kg, entry tension 25k for the 6th (last) bus.
Figure 1 summarizes the above results obtained by rolling at 0.5 g/w'' and using a coolant nozzle. It was confirmed that a thin plate material free of chatter marks could be appropriately rolled by discharging and supplying it to the final bus and the pre-final bus at kg/cJ or less.

For rolled material storms 1 to 6, even if passes 1 to 5 satisfy the conditions of the present invention, the discharge pressure in the final 6 passes is 1.
．． 0 kg/co! If this is the case, the occurrence of chatter marks is unavoidable, and even if the 6th pass satisfies the conditions of the present invention in the case of 11th and 12th passes, the conditions of the present invention are satisfied in the 5th pass immediately before that. If not, this indicates that the chatter marks generated in the fifth pass cannot be erased in the sixth pass, and some chatter marks remain. In addition, in the case of floors 11 and 12, if the discharge pressure in the fifth pass is set to 0.5 kg/cot, a thin plate without chatter marks can be obtained, while in the case of floors 7 and 8, When the pass coolant pressure was set to 0.6 kg/cnT, some chatter marks were still observed.

"Effects of the Invention" According to the present invention as described above, when rolling a thin plate with a thickness of 0.7 mm or less, chatter marks can be effectively prevented from occurring and a thin plate with good surface quality can be stably produced. However, since it can improve the yield and eliminate the disadvantages of conventional methods, it is an invention that has great industrial effects.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show the technical content of the present invention, and FIG. 2
The figure is an explanatory view showing the configuration of the work roll portion of the rolling stand, and FIG. 3 is an explanatory view showing the structural relationship of the rolling stand portion in an 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-back unroll, 5 is a center cross-apart roll, 6 is a material to be rolled, 7 is an anti-crimping roll, & is a defroll roll.

Claims (1)

[Claims] When using a rolling mill with a work roll diameter of 120 to 60 mm to roll the material to be rolled to an entry side plate thickness of 0.7 mm or less, the entry side (rear) tension is set to 20 kg/mm^2 or more, and rolling oil and Or reduce the cooling water supply pressure to 0.5
A method of rolling to prevent chatter marks, characterized in that the rolling thickness is less than kg/cm^2.