Method for controlling the line difference of hot-rolled threaded steel by slitting rolling

Abstract

The embodiment of the application provides a hot-rolled threaded steel cutting rolling line difference control method, adopts three-line cutting rolling, and a rolled piece passes through pre-finishing rolling equipment including 11#, 12#, 13#, 14#, 15# and 16# in total 6 rolling mills; wherein, the 11# rolling mill adopts non-piercing rolling, the 12# rolling mill cuts a box-shaped hole as a pierce hole, the 13# rolling mill cuts a pre-cutting hole as a pierce hole, the 14# rolling mill cuts a cutting hole as a pierce hole, the 15# rolling mill cuts an elliptical hole as a pierce hole, and the 16# rolling mill cuts a finished round hole as a pierce hole; the width of the rolled piece entering the 11# rolling mill is 6-8mm larger than the height of the rolled piece entering the 12# rolling mill, and the height of the rolled piece entering the 11# rolling mill is matched with the groove bottom width of the 12# rolling mill pierce hole. By using the method of the application, the line difference is controlled, the bar three-line finished product cutting head and tail are obviously shortened, the cold bed disorder steel accident and the shearing steel stacking accident caused by excessively large line difference are greatly reduced or even avoided, and the yield rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thread steel slitting rolling, in particular to a hot-rolled thread steel slitting rolling line difference control method. BACKGROUND

[0002] In hot continuous rolling bar production, slitting is an important way to improve production. The uniformity and stability of slitting in slitting rolling are extremely important, and are one of the factors affecting product quality and yield. Ensuring slitting stability can also reduce safety risks.

[0003] Compared with single-line rolling, multi-line slitting rolling has obvious advantages such as high yield, low energy consumption, fewer rolling passes, and reasonable distribution of motor load. However, the use of slitting rolling technology may cause a technical problem, i.e., unevenness of line difference of each slitting line.

[0004] The direct cause of line difference is that the different front slip values of each finished hole lead to different outlet speeds, resulting in inconsistent lengths of finished thread steel of each slitting line. When line difference occurs, it will cause differences in transverse rib fullness, longitudinal rib height, and mechanical properties of each slitting line. When the line difference is serious, it may cause some parameters to be lower than the waste products of the national standard. Large line difference not only produces waste products, but also may cause skirt steel disorder, misalignment of alignment rollers, and reduction of cold shear cutting efficiency. In summary, the smaller the line difference, the higher the yield, the more stable the production, and the higher the product quality.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application includes, for example, providing a hot-rolled thread steel slitting rolling line difference control method which can effectively control the line difference.

[0007] Embodiments of the present application can be implemented as follows:

[0008] In a first aspect, the present application provides a hot-rolled thread steel slitting rolling line difference control method, which adopts three-line slitting rolling. The rolled piece passes through a pre-finishing rolling device, which includes four 450 rolling mills and two 350 rolling mills arranged in sequence, numbered as 11#, 12#, 13#, 14#, 15#, and 16#; wherein 12# is a vertical rolling mill, and the remaining five are horizontal rolling mills; 11# rolling mill adopts non-pore type rolling, 12# rolling mill adopts box type hole, 13# rolling mill adopts pre-slitting hole type, 14 rolling mill adopts slitting hole type, 15# rolling mill adopts elliptical hole type, and 16# rolling mill adopts finished round hole; the width of the rolled piece entering the 11# rolling mill is 6-8mm larger than the height of the rolled piece entering the 12# rolling mill, and the height of the rolled piece entering the 11# rolling mill is adapted to the slot width of the box type hole of the 12# rolling mill.

[0009] In an optional embodiment, the rolling is used for No. 18 thread steel;

[0010] Preferably, the mill main drive side and passive side of the roll gap value before the start of the adjustment within 0.1mm;

[0011] Preferably, the 11# mill is provided with a sliding guide.

[0012] In an optional embodiment, after the rolling piece passes through the 12# mill, the black band width of the rolling piece edge is 70%-80% of the rolling piece width;

[0013] Preferably, the 13# mill cutting hole is 3%-5% smaller than the middle hole area of the two side holes;

[0014] Preferably, the 13# mill is provided with a double-row wheel guide on the feeding side, and the distance between the two vertical wheels of the guide should be 0.15-0.25mm larger than the height of the rolling piece after passing through the 12# mill;

[0015] Preferably, the 13# mill cutting hole width is 90mm, and the 14# mill cutting hole width is 94.46mm.

[0016] In an optional embodiment, before the rolling piece passes through the pre-finishing rolling equipment, it passes through the rough rolling equipment and the intermediate rolling equipment in sequence, the rough rolling equipment includes 6 650 rolling mills arranged in sequence, numbered 1#, 2#, 3#, 4#, 5# and 6#; the intermediate rolling equipment includes 4 550 rolling mills arranged in sequence, numbered 7#, 8#, 9# and 10#;

[0017] Preferably, the rolling mills of the rough rolling equipment and the intermediate rolling equipment are arranged alternately in horizontal and vertical directions;

[0018] Preferably, the rough rolling equipment and the intermediate rolling equipment adopt an oval-round hole type system.

[0019] In an optional embodiment, after the rolling piece passes through the pre-finishing rolling equipment, it is subjected to finishing rolling, and the finishing rolling equipment includes 17# rolling mill and 18# rolling mill, both of which are 450 rolling mills, and the 17# rolling mill is arranged horizontally and adopts an elliptical hole for cutting.

[0020] Preferably, the 18# rolling mill is a horizontal rolling mill or a vertical rolling mill.

[0021] In an optional embodiment, for the adjacent two rolling mills in the rough rolling equipment and the intermediate rolling equipment, when the latter rolling mill bites the steel, the rolling current or torque of the former rolling mill is 2%-3% less than that of the latter rolling mill.

[0022] In optional embodiments, when the rolled piece passes through the pre-finishing rolling device and the finishing rolling device, the corresponding loop and the pressure roller of the rolling mill are kept symmetrical with respect to the rolled piece; or, when the rolled piece passes through the pre-finishing rolling device and the finishing rolling device, the cross-sectional area of the rolled piece is less than a first preset value and no loop is arranged, if the rolled piece between the adjacent two rolling mills is difficult to be pushed, the rotating speed of the roller of the previous rolling mill is increased;

[0023] Preferably, the first preset value is 1200mm 2 ;

[0024] Preferably, when the loop of any rolling mill in the pre-finishing rolling device and the finishing rolling device is set, the rolled piece changes from a certain arc to a straight line, the height of the loop is increased;

[0025] When the loop of any rolling mill in the pre-finishing rolling device and the finishing rolling device is set, the rolled piece is in a straight line, the rotating speed of the roller of the previous rolling mill is increased;

[0026] When the rolled piece shakes when the second rolling mill in front of any rolling mill in the pre-finishing rolling device and the finishing rolling device throws the steel, the rotating speed of the roller of the previous rolling mill or the height of the loop corresponding to the rolling mill is increased.

[0027] In optional embodiments, when the middle length of the line difference of the head multiple pieces is longer than the length of the two sides, the length difference of the two sides does not exceed a second preset value, and the line difference of the last multiple piece is flat, the tension of the rolled piece passing through the rough rolling device and the intermediate rolling device is increased, and the height of the loop in front of the 14# rolling mill is increased;

[0028] When the middle length of the line difference is longer than the length of the two sides, the difference between the middle and the two sides exceeds a third preset value, and the fluctuation of the line difference of the two sides exceeds a second preset value, the intermediate rolling piece is enlarged, and the cutting hole of the 13# rolling mill is filled;

[0029] When the middle length of the line difference is longer than the length of the two sides, the difference between the middle and the two sides is less than a third preset value, and the fluctuation of the line difference of the two sides is small, the line difference of each multiple piece is not fluctuated or the fluctuation is less than a second preset value, the roll gap of the 13# rolling mill is reduced to make the volume of the metal in the middle hole and the two side holes of the cutting hole equal.

[0030] In optional embodiments, when the middle length of the line difference is shorter than the length of the two sides, and the two sides of the rolled piece passing through the 13# rolling mill are relatively full, the roll gap of the 13# rolling mill is increased;

[0031] When the middle length of the line difference is shorter than the length of the two sides and the intermediate rolling piece is greater than a fourth preset value, the intermediate rolling piece is reduced.

[0032] In optional embodiments, when the line difference appears single-side long and the outer side is relatively full, the inlet of the 13# rolling mill is moved to the inner side; when the difference between the two sides is less than a fifth preset value or the inner side is relatively full, the roller is replaced.

[0033] If the linear difference of the rolled piece changes regularly when passing through a certain section of the cooling bed of any rolling mill, the heating process is adjusted to make the temperature of the rolled piece tend to be uniform.

[0034] The beneficial effects of the embodiments of the present application include, for example:

[0035] The method of the present application is used to control the linear difference, the obvious shortening of the head and tail of the bar three-wire finished product, the greatly reduced or even avoided accident of cold bed disorder and the accident of shearing pile caused by too large linear difference, and the improved yield. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0037] Figure 1 The figure is a schematic diagram of the slitting hole of the 12# to 17# rolling mill;

[0038] Figure 2 The figure is a schematic diagram of the slitting hole of the 13# and 14# rolling mill in the embodiments;

[0039] Figure 3 The figure is a schematic diagram of the slitting hole of the 13# and 14# rolling mill in the comparative examples. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are 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 can be arranged and designed in various different configurations.

[0041] 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 in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0042] It should be noted that: similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0043] In the description of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0044] In addition, if the terms "first", "second" and the like appear, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0045] It should be noted that the features in the embodiments of the present application can be combined with each other without conflict.

[0046] Please refer to Figure 1 The present embodiment provides a hot-rolled threaded steel cutting rolling line difference control method, which adopts three-wire cutting rolling, and the rolled piece passes through a pre-finishing rolling equipment, the pre-finishing rolling equipment includes four 450 rolling mills and two 350 rolling mills arranged in sequence, and the numbers are 11#, 12#, 13#, 14#, 15# and 16# respectively; wherein, the 12# rolling mill is a vertical rolling mill, and the remaining five rolling mills are horizontal rolling mills; as shown in Figure 1 The 11# rolling mill adopts non-hole type rolling, the 12# rolling mill adopts box type hole, the 13# rolling mill adopts pre-cutting hole type, the 14# rolling mill adopts cutting hole type, the 15# rolling mill adopts oval hole type, and the 16# rolling mill adopts finished round hole; the width of the rolled piece entering the 11# rolling mill is 6-8mm larger than the height of the rolled piece entering the 12# rolling mill, and the height of the rolled piece entering the 11# rolling mill is adapted to the groove bottom width of the box type hole of the 12# rolling mill.

[0047] The 11# rolling mill selects non-hole type, and the flat roll is characterized by unlimited spread relative to the hole type roll, mainly free spread, drum-shaped spread on both sides, and relatively small elongation and cross-sectional shrinkage.

[0048] In order to meet the correction amount of the box type hole of the next pass 12# rolling mill, the material width of the 11# rolling mill is 6-8mm larger than the material height of the 12# rolling mill. If the material width is too small, the rolled piece will cause the two side holes to be underfilled when cutting in the 13# rolling mill, and the line difference will appear as the middle being long and the two sides being short. If the material width is too large, the head is prone to side bending, and even the steel is piled up at the exit. The material height of the 11# rolling mill should be consistent with the groove bottom width of the box type hole of the 12# rolling mill. If the material height is too small, the rolled piece will be rolled diagonally in the box type hole, affecting the service life of the 12# rolling mill inlet.

[0049] In other embodiments of the present application, the rolling for No. 18 threaded steel.

[0050] In other embodiments of the present application, the mill main drive end and passive end before starting the adjustment gap value is within 0.1mm, to prevent the two ends of the roll gap inconsistent caused by each hole in the rolling piece extension inconsistent produce line difference.

[0051] In other embodiments of the present application, the 11# rolling mill is provided with a sliding guide, the inlet guide of the flat roller stand adopts a sliding guide, which has the advantage of long service life, and compared with the rolling guide, the cost of the guide is saved by about 500,000 yuan per year.

[0052] In other embodiments of the present application, after the rolling piece passes through the 12# rolling mill, the width of the black band on the edge of the rolling piece accounts for 70%-80% of the width of the rolling piece. The 12# rolling mill box type hole is a vertical box hole with a certain side wall slope, which aims to flatten the drum-shaped spread generated in K8 pass to provide good conditions for the next pass pre-cutting. In actual production process, the reduction of 12# rolling mill needs to be strictly controlled. If the reduction is too small, it cannot play a role in trimming, and if the reduction is too large, it is easy to cause double drum deformation on both sides, resulting in irregular material shape and affecting the stability of rolling.

[0053] In actual production process, since the rolling mill is cooled by cooling water, the temperature of the rolling mill is much lower than that of the rolling piece. The deformed part of the rolling piece in contact with the rolling mill will conduct heat, and a "black band" different from the undeformed area will appear on the edge of the rolling piece. When observing in the same horizontal direction, the width of the black band accounts for 70%-80% which is relatively ideal.

[0054] In other embodiments of the present application, the middle hole area of the 13# rolling mill cutting hole is 3%-5% smaller than the area of the two side holes.

[0055] Pre-cutting pass is an important factor to determine the distribution of material shape in each hole type, and is also the most direct factor affecting line difference. When designing the pre-cutting hole, if the areas of the three holes are designed to be the same, the line difference is difficult to adjust. If the area of the side hole is designed to be too large, the line difference on both sides will be too long and cannot be adjusted. Therefore, the area of the middle hole is 3%-5% smaller than that of the two side holes. When the rolling piece is not full in the hole type, the hole type side wall has no supporting effect on the rolling piece, so the size of the rolling piece on both sides after cutting will fluctuate, and the size of the two finished products will also change randomly, making it difficult to control the "three line difference". Too large reduction will accelerate the wear of the hole type; too small reduction will increase the load of the rear rolling mill.

[0056] In other embodiments of the present application, a double-row wheel guide is arranged on the feeding side of the 13# rolling mill, and the distance between the two vertical wheels of the guide should be 0.15-0.25mm larger than the height of the rolling piece after passing through the 12# rolling mill.

[0057] 13# rolling mill entrance uses double-row guide, in actual control process, the distance between vertical wheels should be larger than 0.2mm of the material height of 12# rolling mill, and the rolling piece can move a little inside the entrance of 13# rolling mill. If the distance is too large, the vertical wheels of the guide of 12# rolling mill entrance cannot guide the rolling piece into the middle of the pass, and the rolling piece is easy to deviate or twist, which is not easy to control. If the distance is too small, the vertical wheels of the guide of 12# rolling mill entrance will be under too large stress, and the service life of the entrance guide will be shortened.

[0058] In other embodiments of the present application, the slit hole width of the 13# rolling mill is 90mm, and the slit hole width of the 14# rolling mill is 94.46mm, as shown in Figure 2 .

[0059] In the present application, a comparative example is provided, on the basis of the foregoing embodiment, the slit hole width of the 13# rolling mill is 91.6mm, and the slit hole width of the 14# rolling mill is 96.01mm, as shown in Figure 3 .

[0060] The size of the slit hole of the rolling mill has a great influence on the line difference. If the slit hole is too large, the line difference in the comparative example is long in the middle and short on both sides. In order to ensure that the line difference is flat, the post worker will collect small pre-slit hole type material, so that the amount of metal flowing to both sides in the middle pass increases, which leads to rapid wear of the slit wedge, and the line difference will again be long in the middle and short on both sides. The operator will continue to collect small pre-slit hole material, thereby forming a vicious cycle, resulting in a non-durable pass. In addition, the pre-slit hole material is too large, which also makes it difficult to digest the subsequent pass, the finished product is heavy, the negative deviation is not easy to control, and the production cost per ton of steel increases. After the slit hole is reset in the foregoing embodiment, the problems of non-durable pass and high negative deviation are effectively improved. In other embodiments of the present application, before the rolling piece passes through the pre-precision rolling equipment, it first passes through the rough rolling equipment and the intermediate rolling equipment in sequence. The rough rolling equipment includes 6 650 rolling mills arranged in sequence, numbered 1#, 2#, 3#, 4#, 5# and 6# in sequence. The intermediate rolling equipment includes 4 550 rolling mills arranged in sequence, numbered 7#, 8#, 9# and 10# in sequence.

[0061] In other embodiments of the present application, the rolling mills of the rough rolling equipment and the intermediate rolling equipment are arranged alternately in a horizontal and vertical manner.

[0062] In other embodiments of the present application, the rough rolling equipment and the intermediate rolling equipment both adopt an oval-round hole system.

[0063] The ellipse-round hole type system refers to a hole type system composed of alternately arranged ellipse and round holes. The hole type system has the advantages of stable rolling, uniform deformation, and uniform roll wear, and the rolled piece is not prone to appear reverse rolling and other phenomena. Stable intermediate rolling stock is a prerequisite for ensuring stable slitting. The size of the intermediate rolling stock should be such that the stock width of the 11# rolling mill satisfies the fullness of the pre-slitting hole type of the 13# rolling mill. In actual production, the fullness of the two sides is judged by the method of burning wood marks, so that the stock at the head of the 13# rolling mill is full on both sides, the stock at the tail is slightly out of ear, and the three-line difference of the finished product is flat and level.

[0064] In other embodiments of the present application, the rolled piece is subjected to pre-finishing rolling after the pre-finishing rolling equipment, and the finishing rolling equipment includes a 17# rolling mill and an 18# rolling mill, both of which are 450 rolling mills, and the 17# rolling mill is horizontally arranged and adopts an ellipse hole for slitting;

[0065] In other embodiments of the present application, the 18# rolling mill is a horizontal rolling mill or a vertical rolling mill.

[0066] The finishing rolling can be two or three 450 rolling mills, wherein the 17# rolling mill is horizontally arranged and adopts an ellipse hole, and in order to increase the specification of the production line, the 18# rolling mill can be 18H and 18V. When small specification threaded steel is produced by slitting rolling, 18H horizontal rolling mill is selected, and when large specification threaded steel is produced, 18V vertical rolling mill is selected.

[0067] In other embodiments of the present application, for the adjacent two rolling mills in the rough rolling equipment and the intermediate rolling equipment, when the latter rolling mill bites the steel, the rolling current or torque of the former rolling mill is 2%-3% less than that of the latter rolling mill.

[0068] In other embodiments of the present application, when the rolled piece passes through the pre-finishing rolling equipment and the finishing rolling equipment, the rolled piece has a symmetrical arc between the corresponding loop wheel and the pressure wheel of the rolling mill; or, when the cross-sectional area of the rolled piece is less than a first preset value and no loop is set, if the rolled piece between the adjacent two rolling mills is difficult to move, the rotational speed of the rolling mill is increased.

[0069] Preferably, the first preset value is 1200mm 2 .

[0070] In other embodiments of the present application, if the rolled piece changes from a certain arc to a straight line after the loop of any rolling mill in the pre-finishing rolling equipment and the finishing rolling equipment is set, the set height of the loop is increased;

[0071] If the rolled piece is in a straight line when the loop of any rolling mill in the pre-finishing rolling equipment and the finishing rolling equipment is set, the rotational speed of the rolling mill is increased;

[0072] If the workpiece shakes when the second rolling mill before any of the rolling mills in the pre-finishing rolling equipment and the finishing rolling equipment throws the workpiece, the rotating speed of the rolling mill before the workpiece is increased or the height of the corresponding loop of the rolling mill is increased.

[0073] In the tension control, the genetic effect of the shape change of the workpiece cannot be ignored. That is, the tension between the 1# and 2# rolling mills is too large, the elongation is increased, the shape height is unchanged, the spread is small, the width of the workpiece out of the 1# rolling mill is small, the reduction of the 2# rolling mill is small, and the width of the workpiece out of the 2# rolling mill is small. If the tension exists between each stand, the tension effects are superimposed, and when the tension adjustment is poor, the ear of the head of the finished product is small and the ear of the tail of the finished product is large. When the tension adjustment is poor, the first and second sections of the finished product are prone to have small or no ears. In the field, it is commonly known as "small head and large tail".

[0074] In actual control, when the tension adjustment is poor, the line difference of the first several sections of the workpiece is large, and the line difference of the last section of the workpiece is flat. At this time, the stands with unequal second flow on the rolling line need to be adjusted. In the rough and intermediate rolling, the rolling current can be used for judgment. That is, when the current (torque) of the current stand is 2%-3% smaller than the current (torque) of the previous stand after the workpiece is bitten, it is the best. The tension of the pre-finishing rolling and the finishing rolling can be judged according to the shape of the workpiece in the loop. When the workpiece between the loop lifting wheel and the pressure wheel has a symmetrical arc, the tension state is good. If the workpiece changes from a certain arc to a straight line after the loop is lifted, it indicates that the set height of the loop is low and the workpiece is pulled. The set height of the loop needs to be increased. If the workpiece is in a straight line when the loop is lifted, it indicates that the rotating speed of the previous stand is low, and the rotating speed of the previous stand needs to be increased. When the workpiece is thrown by the second stand before the loop, the workpiece does not shake, indicating that the tension state is good. If the workpiece shakes, it indicates that the tension is large, and the rotating speed of the previous stand or the height of the loop needs to be increased. When the cross-sectional area of the workpiece is small and there is no loop, a steel rod can be used to move the workpiece. When the tension state is good, the workpiece can be easily moved. When it is difficult to move the workpiece, it indicates that there is a large tension between the previous and subsequent rolling mills, and the rotating speed of the previous stand needs to be increased.

[0075] In other embodiments of the present application, if the line difference of the head section is long in the middle and short at both ends, the line difference at both ends does not exceed the second preset value, and the line difference of the last section is flat, the tension of the workpiece passing through the rough rolling equipment and the intermediate rolling equipment is increased, and the height of the loop before the 14# rolling mill is increased.

[0076] If the line difference is long in the middle and short at both ends, and the line difference between the middle and both ends exceeds the third preset value, and the line difference at both ends fluctuates more than the second preset value, the incoming material of the intermediate rolling section is enlarged, and the cutting hole of the 13# rolling mill is fully filled.

[0077] If the line difference is long in the middle and short at both ends, but the line difference is less than the third preset value, and the line difference at both ends has no fluctuation, and the line difference of each section has no fluctuation or the fluctuation is less than the second preset value, the roll gap of the 13# rolling mill is reduced to make the metal volume in the middle hole and the holes at both ends of the cutting hole equal.

[0078] When the line difference appears to be longer in the middle and shorter at both ends, it can be analyzed from three aspects. 1. When the tension is larger, the line difference feature is that the head several times will appear to be longer in the middle and shorter at both ends, and the line difference at both ends will not appear to be larger fluctuation, and the last time line difference is flat, at this time, the rough intermediate rolling tension and the active loop height before the 14# rolling mill are adjusted to be larger, to prevent the line difference from being caused by the uneven head and tail of the drawn steel. 2. When the line difference is longer in the middle and shorter at both ends, and the line difference between the middle and both ends is far apart, and the line difference at both ends fluctuates greatly, it is longer outside for a while, and it is longer inside for a while, which indicates that the 13# rolling mill pass does not support the rolled piece, and the filling degree of the rolled piece ground by wood for the 13# rolling mill is poor, and the incoming material width is smaller. First, check whether the material shape of the 12# rolling mill and the 11# rolling mill meets the requirements of 1.1 and 1.2, if not, the incoming material of the intermediate rolling is enlarged, so that the 13# rolling mill pre-cutting pass is filled, and the rolled piece is automatically aligned in the pass, so that the line difference is stable and flat. 3. When the line difference is longer in the middle and shorter at both ends, and the line difference is less, the line difference at both ends has no fluctuation or small fluctuation, which indicates that the 13# rolling mill gap value is too large, and the 13# rolling mill gap needs to be reduced to ensure that the metal volume in the three grooves of the rolled piece is equal.

[0079] In the present application, the line difference of more than 200mm in the head length difference can be relatively large, and within 30mm can be considered to be relatively small or can be considered to be no fluctuation, and the middle value is moderate.

[0080] In other embodiments of the present application, if the line difference appears to be shorter in the middle and longer at both ends, and the filling degree of the rolled piece passing through the 13# rolling mill is relatively full at both sides, the roller gap of the 13# rolling mill is increased.

[0081] If the line difference appears to be shorter in the middle and longer at both ends, and the incoming material of the intermediate rolling equipment is greater than the fourth preset value, the incoming material of the intermediate rolling equipment is reduced.

[0082] When the line difference appears to be shorter in the middle and longer at both ends, it indicates that the pre-cutting pass of the 13# rolling mill is overfilled. 1. If the phenomenon occurs when the specification is changed, the filling degree of the rolled piece ground by wood for the 13# rolling mill is relatively full at both sides, and even ears are formed at both sides, so the 13# rolling mill gap is enlarged to reduce the metal flow of the two side grooves. 2. Check the incoming material of the intermediate rolling, if the incoming material is larger, for example, larger than the standard material, it will make the 11# rolling mill expand too much, and the 13# rolling mill pass is full at both sides, resulting in too large line difference, at this time, the incoming material of the intermediate rolling is reduced until the line difference is flat.

[0083] In other embodiments of the present application, if the line difference appears to be longer on one side and the filling degree of the outer side is relatively full than the inner side, the 13# rolling mill inlet is moved to the inner side; if the filling degree of both sides is less than the fifth preset value or the filling degree of the inner side is relatively full than the outer side, the roller is replaced.

[0084] When the line difference appears unilateral length, it is caused by too much unilateral material type. Taking the example of outside long and inside short, the following analysis is made. 1. First, use the wood mill 13# roller to pre-cut the filling degree of the two sides of the pass. If the filling degree of the outside is more than that of the inside, the 13# roller inlet needs to be moved to the inside. 2. If the filling degrees of the two sides are similar, for example, when using wood mill roller, the wear depth of the two sides of the roller is within 0.5mm, or the filling degree of the inside is more than that of the outside, it is caused by uneven wear of the pass, and the roller reaching the quota can be replaced and adjusted.

[0085] If the line difference changes regularly when the rolled piece passes through a certain section of the cooling bed of any roller, the heating process is adjusted to make the temperature of the rolled piece uniform.

[0086] Generally, due to the existence of micro-tension in the rolling process, the cross-sectional area of the rolled piece gradually increases from the beginning to the end, and the line difference of the finished product changes regularly, that is, the two sides of the head are slightly shorter, and the line difference of the two sides gradually increases with the increase of the number of cooling beds. When the line difference of a certain section in the middle of the cooling bed changes regularly, most of the time, the billet is heated unevenly, and the heating process is adjusted to uniformize the temperature of the rolled piece.

[0087] It should be noted that the various preset values in the embodiments of the present application can be pre-set according to the process conditions and error range.

[0088] Using the method of the present application to control the line difference, the total length of the head and tail of the three-line finished product is shortened by more than 150mm, the present head is stably within 100mm, the tail is stably within 250mm; the cold bed disorder steel accident is 0, the shearing and stacking accident caused by too large line difference is 0; the yield of finished products is increased by about 0.2%.

[0089] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of controlling the line difference in a hot-rolled threaded steel slitting rolling line, characterized by, The three-line slitting rolling is adopted, and the rolled piece passes through a pre-finishing rolling device, the pre-finishing rolling device comprising four 450 rolling mills and two 350 rolling mills arranged in sequence, and the numbers of the rolling mills are 11#, 12#, 13#, 14#, 15# and 16# respectively; wherein, the 12# rolling mill is a vertical rolling mill, and the other five rolling mills are horizontal rolling mills; the 11# rolling mill adopts non-piercing rolling, the 12# rolling mill adopts box piercing, the 13# rolling mill adopts pre-slitting piercing, the 14# rolling mill adopts slitting piercing, the 15# rolling mill adopts oval piercing, and the 16# rolling mill adopts finished round piercing; the width of the rolled piece entering the 11# rolling mill is 6-8mm larger than the height of the rolled piece entering the 12# rolling mill, and the height of the rolled piece entering the 11# rolling mill is matched with the groove bottom width of the box piercing of the 12# rolling mill; After the rolled piece passes through the 12# rolling mill, the black band width of the edge of the rolled piece accounts for 70%-80% of the width of the rolled piece; Before the rolled piece passes through the pre-finishing rolling device, the rolled piece passes through a rough rolling device and a medium rolling device in sequence, the rough rolling device comprising six 650 rolling mills arranged in sequence, and the numbers of the rolling mills are 1#, 2#, 3#, 4#, 5# and 6# respectively; the medium rolling device comprising four 550 rolling mills arranged in sequence, and the numbers of the rolling mills are 7#, 8#, 9# and 10# respectively; for the adjacent two rolling mills in the rough rolling device and the medium rolling device, the rolling current or torque of the former rolling mill is 2%-3% less than that of the latter rolling mill when the latter rolling mill bites the steel; If the line difference of the head section is longer in the middle and shorter at both sides, and the length difference of the line difference at both sides does not exceed the second preset value, and the line difference of the last section is flat, the tension of the rolled piece when passing through the rough rolling device and the medium rolling device is increased, and the loop height in front of the 14# rolling mill is also increased; If the line difference is longer in the middle and shorter at both sides, and the difference between the middle and the two sides exceeds the third preset value, and the fluctuation of the line difference at both sides exceeds the second preset value, the incoming material of the medium rolling section is enlarged, so that the slitting hole of the 13# rolling mill is fully filled; If the line difference is longer in the middle and shorter at both sides, but the difference is less than the third preset value, and the line difference at both sides has no fluctuation, and the line difference of each section has no fluctuation or the fluctuation is less than the second preset value, the roll gap of the 13# rolling mill is reduced, so that the metal volume in the middle hole and the side holes of the slitting hole is equal.

2. The method of controlling the line difference in the hot-rolled threaded steel slitting rolling line according to claim 1, characterized by, The rolling is used for 18# screw steel.

3. The method of controlling the line difference in the hot-rolled threaded steel cutting rolling line according to claim 2, characterized by, Before starting, the difference between the roll gap values on both sides of the driving end and the passive end of the rolling mill is adjusted to be within 0.1mm.

4. The method of controlling the line difference in the hot-rolled threaded steel cutting rolling line according to claim 2, characterized by, The 11# rolling mill is provided with a sliding guide.

5. The method of controlling the line difference in the hot-rolled threaded steel cutting rolling line according to claim 1, characterized by, The middle hole area of the slitting hole of the 13# rolling mill is 3%-5% less than the side hole area.

6. The method of controlling the line difference in the hot-rolled threaded steel cutting rolling line according to claim 5, characterized by, A double-row wheel guide is arranged on the feeding side of the 13# rolling mill, and the distance between the two vertical wheels of the guide is 0.15-0.25mm larger than the height of the rolled piece after passing through the 12# rolling mill.

7. The method of controlling the line difference in the hot-rolled threaded steel cutting rolling line according to claim 5, characterized by, The width of the slitting hole of the 13# rolling mill is 90mm, and the width of the slitting hole of the 14# rolling mill is 94.46mm.

8. The method of controlling line difference in the process of cutting and rolling of hot-rolled threaded steel according to claim 1, characterized in that, The rolling mills of the rough rolling device and the medium rolling device are arranged alternately in horizontal and vertical directions.

9. The method of controlling line difference in a hot rolled threaded steel bar slitting rolling line according to claim 1, wherein, The rough rolling device and the medium rolling device adopt an oval-round hole system.

10. The method of controlling line difference in a hot rolled threaded steel bar slitting rolling line according to claim 1, wherein, The rolled piece passes through a finishing rolling device after passing through the pre-finishing rolling device, the finishing rolling device comprising a 17# rolling mill and a 18# rolling mill, and the 17# rolling mill and the 18# rolling mill are both 450 rolling mills, and the 17# rolling mill is arranged horizontally and adopts an oval slitting hole.

11. The method of controlling the line difference in the hot-rolled threaded steel cutting rolling line according to claim 10, characterized by, The 18# rolling mill is a horizontal rolling mill or a vertical rolling mill.

12. The method of controlling line difference in the process of cutting and rolling of hot-rolled threaded steel according to claim 1, wherein When the rolled piece passes through the pre-finishing rolling equipment and the finishing rolling equipment, the rolled piece between the corresponding loop-up roller and the pressure roller of the rolling mill is kept symmetrical in curvature; or, when the rolled piece passes through the pre-finishing rolling equipment and the finishing rolling equipment, the cross-sectional area of the rolled piece is less than a first preset value and no loop is arranged, if the rolled piece between the adjacent two rolling mills is difficult to be pushed, the rotating speed of the roller of the previous rolling mill is increased.

13. The method of controlling the line difference of a hot-rolled threaded steel cut-rolling line according to claim 12, characterized by, The first preset value is 1200mm 2 .

14. The method of controlling line difference in a hot rolled threaded steel bar slitting rolling line according to claim 12, wherein, If the rolled piece changes from the curvature to the straight line after the loop of any rolling mill in the pre-finishing rolling equipment and the finishing rolling equipment is looped up, the set height of the loop is increased. If the rolled piece is in the straight line when the loop of any rolling mill in the pre-finishing rolling equipment and the finishing rolling equipment is looped up, the rotating speed of the roller of the previous rolling mill is increased. If the rolled piece shakes when the second rolling mill in front of any rolling mill in the pre-finishing rolling equipment and the finishing rolling equipment throws the steel, the rotating speed of the roller of the previous rolling mill or the height of the loop corresponding to the rolling mill is increased.

15. The method of controlling line difference in a hot-rolled threaded steel cutting rolling line according to claim 1, characterized by, If the line difference appears to be short in the middle and long on both sides, and the rolled piece passing through the 13# rolling mill is full on both sides, the roll gap of the 13# rolling mill is increased. If the line difference appears to be short in the middle and long on both sides, and the incoming material of the medium rolling equipment is greater than a fourth preset value, the incoming material of the medium rolling equipment is reduced.

16. The method of controlling line difference in the process of cutting and rolling of hot-rolled threaded steel according to claim 1, wherein If the line difference appears to be long on one side and the fullness on the outer side is greater than that on the inner side, the inlet of the 13# rolling mill is moved to the inner side; if the difference between the fullness on both sides is less than a fifth preset value or the fullness on the inner side is greater than that on the outer side, the roller is replaced. If the line difference changes regularly when the rolled piece passes through a certain section of the cooling bed of any rolling mill, the heating process is adjusted to make the temperature of the rolled piece tend to be uniform.

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