A method for controlling local draw reduction of a cold-rolled stock coil

Abstract

The application discloses a kind of control methods of local draw narrow of cold-rolled raw material roll, belong to the technical field of rolling steel, comprising: the ovality control standard adjustment of coiling pinch roll is ±20 μm;Coiling threading tension is set as 50% of the body strip steel tension, the lowest adjustment of body tension coefficient is 0.4, yield coefficient is adjusted to 0.35;The lead rate of reel is set to 14%, the lead rate of pinch roll is set to 16%, so that the coiling speed of reel is lower than the speed of pinch roll, reduce the tension between pinch roll and reel;Finish rolling temperature is adjusted to 880±20 DEG C;Cooling mode is adjusted to post-cooling mode.The application reduces the speed and tension setting of pinch roll and reel by reducing the build-up tension when coiling and finish rolling, finally reduces the threading tension between coiler and finish rolling mill.Lowering finish rolling temperature appropriately, increase product strength, reduce product draw narrow when build-up.Solve the difficulty of local draw narrow of cold-rolled raw material roll, stabilize product quality.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steel rolling, and particularly relates to a control method for local narrowing of a cold-rolling raw material coil. BACKGROUND

[0002] In hot-rolled products, cold-rolling raw material coils account for a large proportion, and the products are required to have high plasticity, toughness and welding performance, good pressure processing performance, but low product strength. The production features are high finishing-rolling final-rolling temperature and coiling temperature, high rolling speed, and low product strength itself, so that the strength is further reduced at a high temperature during coiling, and local narrowing easily occurs during finishing-rolling and coiling.

[0003] From Figure 1 It can be seen from the finishing-rolling exit width (FM Exit Width - finishing-rolling exit width data) that the actual strip width measured by the finishing-rolling exit width gauge is in the range of 1260mm-1263mm, which completely meets the width requirement of the product target width of 1250mm.

[0004] The actual measurement of the finished steel coil width is performed at the position of 146m-152m, and the actual measurement width is 1248-1253mm, which has a maximum difference of 12mm from the exit width measured by the gauge. According to the actual length from the finishing-rolling exit to the coiler, it is determined that the strip head reaches the coiler, and the strip produces narrowing before the first group of layer cooling headers during coiling of 2-3 turns. Through analysis, the main reason for the narrowing is that the strip strength is low, the temperature is high, the specification is thin and narrow, and the coiling tension is too large during the coiling building-up stage, so that the narrowing occurs at the position of the minimum strip deformation resistance (before the first group of layer cooling headers, the steel coil has not been cooled, the temperature is the highest, and the strength is the lowest).

[0005] The product cannot meet the quality requirements of the cold-rolling raw material coil during the production in the cold-rolling process due to the local narrowing, which restricts the production of the product. SUMMARY

[0006] The present application aims to meet the actual needs, and provides a control method for local narrowing of a cold-rolling raw material coil, which reduces the speed and tension setting of the pinch roll and the winding drum during coiling and finishing-rolling building-up, and finally reduces the strip passing tension between the coiler and the finishing-rolling machine. The final-rolling temperature is appropriately reduced, the product strength is increased, and the narrowing of the product during building-up is reduced. The difficulty of local narrowing of the cold-rolling raw material coil is solved, and the product quality is stabilized.

[0007] To achieve the above technical purposes, the present application aims to provide a control method for local narrowing of a cold-rolling raw material coil, which comprises the following steps:

[0008] Winding pinch roll ovality control: the ovality control standard of the winding pinch roll is adjusted to ±20μm;

[0009] Coiling tension control: the coiling threading tension is set as 50% of the body strip steel tension, the body tension coefficient is adjusted to be the lowest 0.4, and the yield coefficient is adjusted to be 0.35;

[0010] Coiling lead rate control: the coiling drum lead rate is set to be 14%, the pinch roll lead rate is set to be 16%, the coiling speed of the coiling drum is lower than the pinch roll speed, and the tension between the pinch roll and the coiling drum is reduced;

[0011] Temperature control: the finish rolling temperature is adjusted to be 880±20℃;

[0012] Cooling control: the cooling mode is adjusted to be the post-cooling mode, so that the steel coil has sufficient grain growth time after the finish rolling process is rolled, and the influence of the coiling temperature reduction on the performance is eliminated.

[0013] Preferably, the thickness of the cold-rolled raw material coil is not greater than 2.5mm.

[0014] Preferably, the ovality control standard of the coiling pinch roll is adjusted to be -20μm.

[0015] Preferably, the ovality control standard of the coiling pinch roll is adjusted to be 20μm.

[0016] Preferably, the finish rolling temperature is adjusted to be 860℃.

[0017] Preferably, the finish rolling temperature is adjusted to be 900℃.

[0018] Compared with the prior art, the application has the advantages and positive effects that:

[0019] The application reduces the speed and tension setting of the pinch roll and the coiling drum when building tension, and finally reduces the threading tension between the coiling machine and the finish rolling machine. The finish rolling temperature is appropriately reduced, the product strength is increased, and the product is reduced in the building tension. The difficulty of local narrowing of the cold-rolled raw material coil is solved, and the product quality is stabilized.

[0020] The application is suitable for various conventional hot continuous rolling processes, has a wide application range, has good technical radiation ability, and provides important technical support for the development of hot-rolled product specifications. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1A finish rolling exit width diagram set forth in the background of the present application is shown. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0024] The present application provides a control method for locally narrowing a cold-rolled raw material coil, comprising:

[0025] Coiling pinch roll ovality control: the ovality control standard of the coiling pinch roll is adjusted from ±30μm to ±20μm (for example, the ovality control standard of the coiling pinch roll is adjusted to -20μm or 20μm), which improves the equipment precision and reduces the pressure fluctuation of the pinch roll during coiling and finish rolling build-up, thereby improving the stability during coiling and finish rolling build-up.

[0026] Coiling tension control: the coiling threading tension is set to 50% of the body strip tension, the body tension coefficient is adjusted to a minimum of 0.4, and the yield coefficient is adjusted to 0.35.

[0027] Coiling lead rate control: the winding drum lead rate is set to 14%, and the pinch roll lead rate is set to 16%, so that the winding speed of the winding drum is lower than the speed of the pinch roll, thereby reducing the tension between the pinch roll and the winding drum.

[0028] Temperature control: the finish rolling temperature is adjusted from 900±20℃ to 880±20℃ (for example, adjusted to 860℃ or 900℃).

[0029] Cooling control: the cooling mode is adjusted from the uniform cooling mode to the post-cooling mode, so that the coil has sufficient grain growth time after finish rolling process to eliminate the influence of the reduced coiling temperature on the performance.

[0030] The present application reduces the coiling threading tension coefficient.

[0031] The present application reduces the speed of the coiling pinch roll and the winding drum, thereby reducing the tension between the finish rolling process.

[0032] The thickness of the cold-rolled raw material coil is not greater than 2.5mm.

[0033] The specific technical operation scheme is:

[0034] I. Process path: heating furnace → rough rolling mill → finishing rolling mill → laminar flow cooling → coiling;

[0035] II. Applicable specifications:

[0036] Table 1 is a specification table

[0037] Steel grade Applicable specification Cold rolled stock coil series ≤ 2.5 mm

[0038] III. Measures:

[0039] The ovality control precision of the pinch roll is improved, the pressure fluctuation caused by the excessive ovality of the pinch roll is reduced, the lead rate of the coiling pinch roll and the winding drum, that is, the speed in the threading stage is reduced, and the threading tension of the coiling is reduced. It should be noted that the threading tension value cannot be set too low, otherwise the quality defect of the flat wound product roll will be caused. Finally, the finish rolling temperature and the cooling system are properly adjusted according to the product performance requirements to meet the product performance standards.

[0040] The application solves the difficulty of local narrowing in the production process of the cold-rolled raw material roll through the adjustment of the process parameters.

[0041] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for controlling the local narrowing of cold-rolled raw material coils, characterized in that, The thickness of cold-rolled raw material coils shall not exceed 2.5 mm, and the control methods include: Ellipticity control of the take-up pinch roll: The ellipticity control standard of the take-up pinch roll is adjusted to ±20μm; Coiling tension control: The coiling tension is set to 50% of the main strip tension, the main tension coefficient is adjusted to a minimum of 0.4, and the yield coefficient is adjusted to 0.35; Take-up lead rate control: Set the drum lead rate to 14% and the pinch roll lead rate to 16% to make the drum take-up speed lower than the pinch roll speed, thereby reducing the tension between the pinch roll and the drum. Temperature control: The final rolling temperature is adjusted to 880±20℃; Cooling control: The cooling mode is adjusted to post-cooling mode, so that the steel coil has sufficient time for grain growth after the finishing rolling process, eliminating the impact of reduced coiling temperature on performance.

2. The method for controlling local narrowing of cold-rolled raw material coils according to claim 1, characterized in that, The ellipticity control standard for the take-up pinch rolls has been adjusted to -20μm.

3. The method for controlling local narrowing of cold-rolled raw material coils according to claim 1, characterized in that, The ellipticity control standard for the take-up pinch rolls has been adjusted to 20μm.

4. The method for controlling local narrowing of cold-rolled raw material coils according to claim 1, characterized in that, The final rolling temperature was adjusted to 860℃.

5. The method for controlling local narrowing of cold-rolled raw material coils according to claim 1, characterized in that, The final rolling temperature was adjusted to 900℃.

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