A method for rolling a 40mm x 100mm rectangular flat steel

Abstract

A 40mm*100mm rectangular flat steel rolling method, parameters as follows: 1) semi-finished product circle diameter is 100-110mm; 2) the mode of flat roller 5-flat roller 4-K4-flat roller 3-flat roller 2-K2-flat roller 1 is adopted; 3) limiting reduction; 4) the corresponding mill guide opening degree of flat roller 5, flat roller 4, flat roller 3, flat roller 2 is 5-8mm larger than the material shape; the corresponding mill guide opening degree of K4, K2, flat roller 1 is 1-3mm larger than the material shape; 5) limiting guide roller; 6) the K4 slot width is 70-74mm, the slot bottom width is 62-65mm, the K4 hole pattern slot bottom corner R angle radius is 17-19mm, the slot opening corner r angle radius is 9-12mm, the side wall slope is 5-8°, and the slot depth is 42-46mm; the K2 slot width is designed as 40-41.5mm, the slot bottom width is 44-46mm, the K2 hole pattern slot bottom corner R angle radius is 10-12mm, the slot opening corner r angle radius is 9-12mm, the side wall slope is 3-5°, and the slot depth is 38-40mm. Adopting the application can prolong the steel quantity of rolling groove, improve the efficiency and reduce the cost; the obtained finished product size is stable, meets the requirements of customers and national standards, and there is no stress crack in the corner.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of spring steel flat steel rolling, in particular to a 40mm*100mm rectangular flat steel rolling method. BACKGROUND

[0002] At present, there are few domestic spring flat steel manufacturers, the price of flat steel has obvious advantages, and the market demand is large. It is estimated that the demand for spring flat steel will be 8 million tons per year in 2024-2025, and the demand for automobile spring flat steel will be about 3 million tons. In order to achieve lightweight, the automobile industry has adopted a new spring steel plate structure, which is a variable cross-section spring steel plate with the thickest middle section of the single-piece spring and gradually thinned to both ends. Therefore, the automobile spring industry has put forward the demand for rectangular spring flat steel. Because the cross section of the finished product is rectangular, the four corners have small round angles, so it is easy to not fill the corners during rolling. At the same time, improper control of the front pass reduction and incoming material can easily lead to accidents such as folding, scratching, and twisting during rolling. If the R angle of the rectangular flat steel is not properly designed, the stress cannot be released, stress concentration occurs, and fatigue cracks are easily generated.

[0003] Chinese patent application with publication number CN112893454A discloses a 38mm-thick rectangular spring flat steel rolling method, which is implemented according to the following steps: 1. Determine the cross-sectional size of the rectangular spring flat steel, and the round angles of the four corners of the spring flat steel are all R15mm; 2. Redesign the K2 and K4 vertical rolling hole patterns in the spring flat steel rolling production line, wherein the main parameters of the K2 hole pattern are: the distance L between the two rollers is 91mm, the roller round angle R is 15mm, the left roller depth H is 27mm, the width B is 44.62mm, the right roller width b is 38.22mm, and the main parameters of the K4 hole pattern are: the distance L1 between the two rollers is 93mm, the left roller depth H1 is 27mm, the roller round angle r is 8mm, the right roller bottom width B1 is 52.58mm, and the right roller top width B2 is 45mm; 3. The K2 and K4 adopt box hole patterns, and small reduction is adopted for K1-K2 to ensure stable material shape during rolling and meet the quality requirements of the finished product. However, according to section 4.1.3 of GBT 33164.1-2016 Spring Steel for Automotive Suspension Systems Part 1: Hot Rolled Flat Steel, the r angle is 8mm±2mm when the thickness is ≤40mm. However, the K2 roller round angle r of the Chinese patent application with publication number CN112893454A is 15mm, and K2 is the pre-product hole pattern, which is crucial for controlling the r angle of the finished product. Although the above-mentioned patent application is beneficial to solving the stress concentration of the corner of the finished product, it is relatively difficult to control the size of the finished product, and the rolling process is unstable. Moreover, it is only suitable for rolling 38mm-thick rectangular spring flat steel, and is not suitable for rolling rectangular flat steel with a thickness of more than 40mm. SUMMARY

[0004] The technical problem solved by the present application is to overcome the defects of easy crack caused by corner stress concentration during the rolling process of the rectangular flat steel, difficult control of the r angle shape of the finished product, relatively difficult control of the finished product size, and instability during the rolling process, and to provide a 40mm*100mm rectangular flat steel rolling method.

[0005] The technical solution adopted by the present application to solve the technical problem is:

[0006] A 40mm*100mm rectangular flat steel rolling method, and the specific process parameters are as follows:

[0007] 1) The semi-finished product round diameter is 100-110mm;

[0008] 2) The rectangular rolling system adopts the mode of flat roller 5-flat roller 4-K4-flat roller 3-flat roller 2-K2-flat roller 1, wherein K4 and K2 are special hole patterns for 40mm*100mm rectangular flat steel;

[0009] 3) The reduction of flat roller 5 is 36-45mm, the reduction of flat roller 4 is 15-25mm, the reduction of K4 is 18-24mm, the reduction of flat roller 3 is 5-8mm, the reduction of flat roller 2 is 6-8mm, the reduction of K2 is 10-16mm, and the reduction of flat roller 1 is 3-5mm;

[0010] In the rolling program table, the reduction is an important control parameter in the rolling process, and its size directly affects the stability of the rolling process, the product quality after rolling, and the service life of the equipment. If the reduction of each rolling mill, especially the flat roller 5, is too small, it will cause problems such as increase of product surface roughness, wrinkles, and affect the surface quality of the product; at the same time, it will cause the increase of twisting probability between the finishing mill groups, the increase of rolling mill load between the finishing mill groups, and the wear resistance of the rolling groove between the finishing mill groups. Too small reduction will also cause insufficient compensation of solid shrinkage, which may cause problems such as center segregation and center porosity that are not obviously improved. Too large reduction will increase the load of the rack, and may cause the situation of broken roller, and also cause the casting blank to bear excessive extrusion, which may cause the molten steel rich in solute elements to flow to the adjacent bulging area, resulting in white band, negative segregation and reverse V segregation;

[0011] 4) The corresponding rolling mill guide opening of flat roller 5, flat roller 4, flat roller 3 and flat roller 2 is 5-8mm larger than the material type; the corresponding rolling mill guide opening of K4, K2 and flat roller 1 is 1-3mm larger than the material type;

[0012] 5) In order to ensure the stability of the rolling piece in the mill group, the guide roller hole pattern in step 4) is specified, the guide roller R of flat roller 5 and flat roller 4 is 42-46mm, and the guide roller R of flat roller 3 and flat roller 2 is 38-42mm;

[0013] 6) wherein the design K4 slot width (B) is 70-74mm, the slot bottom width (b) is 62-65mm, the K4 hole type slot bottom fillet R angle radius is 17-19mm, the slot opening fillet r angle radius is 9-12mm, the side wall slope is 5-8°, and the slot depth (H) is 42-46mm; the design K2 slot width (B) is 40-41.5mm, the slot bottom width (b) is 44-46mm, the K2 hole type slot bottom fillet R angle radius is 10-12mm, the slot opening fillet r angle radius is 9-12mm, the side wall slope is 3-5°, and the slot depth (H) is 38-40mm.

[0014] Further, the rectangular flat steel error of the present application is controlled to 40±0.5mm and 100±10mm.

[0015] The scheme of the present application is also suitable for rolling of (40-49) mm×100mm rectangular flat steel.

[0016] The key of the present application lies in controlling the reduction, slot width, slot bottom width, slot bottom fillet R angle and other parameters. Too small slot width and slot width gap will cause excessive wear of the roll, and even damage; the surface quality of the steel will decrease, such as indentation, scratch and the like. Too large slot width and slot width gap will affect the dimensional accuracy of the rolled steel, such as uneven thickness. At the same time, unreasonable design of the slot width and slot width gap will easily lead to twisted steel. Too small slot bottom fillet R angle will cause stress concentration between the steel and the roll during rolling, increase the risk of roll damage, and the surface quality of the steel may be affected, such as crack, indentation and the like. Too large R angle will make the shape of the rolled steel not meet the requirements, affecting the dimensional accuracy.

[0017] Principles and beneficial effects of the present application:

[0018] 1) The present application has low requirement for semi-finished round, and each steel rolling plant can freely select according to its own equipment capacity and raw material blank section, and the diameter of the semi-finished round is controlled to 100-110mm;

[0019] 2) The rectangular rolling system adopts the mode of flat roll 5-flat roll 4-K4-flat roll 3-flat roll 2-K2-flat roll 1, wherein the flat roll 5 and the flat roll 4 are a small system, and the reduction can be appropriately increased or decreased according to the actual situation. If the rolling groove wears too fast, the rolling mill can be opened to reduce the pressure of the rolling groove. The flat roll 3 and the flat roll 2 are a small system as above. At the same time, if any one of the flat roll 5, the flat roll 4, the flat roll 3 and the flat roll 2 corresponding to the rolling mill fails, it can be temporarily taken offline to quickly restore production;

[0020] 3) Controlling the reduction of each pass is beneficial to prolong the steel quantity of the rolling groove, improve the efficiency and reduce the cost;

[0021] 4) In the production process, the guide opening degree of the rolling mill plays a crucial role, and if the guide opening degree is too large, the rolled piece is prone to twisting, biting and deviation, thereby causing serious accidents such as steel stacking and steel running, and causing serious damage to personnel and equipment. If the guide opening degree is too small, the guide roller is prone to wear, causing indentation and folding quality accidents. Therefore, the opening degree and guide roller pass are standardized in the present application. At the same time, the reduction amount of the flat roller 5, the flat roller 4 and K4 is large, which is beneficial to ensure the internal performance of the product surface;

[0022] 5) Rectangular flat steel is prone to crack due to stress concentration at the corner during rolling, and the finished product r angle shape is difficult to control, because the pass distribution is uneven and the pass design is unreasonable. The R angle radius of the K4 design pass groove bottom is 17-19mm, the R angle radius of the K2 pass groove bottom is 10-12mm, and the R angle gradually decreases, which is beneficial to the control of the finished product R angle. At the same time, the K4 reduction amount is greater than K2, which is beneficial to the stress release of the finished product R angle, and at the same time, the very small reduction amount of the finished rolling mill further releases the corner stress while ensuring the shape of the R angle.

[0023] Advantages of the present application:

[0024] 1. The rectangular rolling system adopts the mode of flat roller 5-flat roller 4-K4-flat roller 3-flat roller 2-K2-flat roller 1. If any one of the flat roller 5, the flat roller 4, the flat roller 3 and the flat roller 2 corresponding to the rolling mill fails, it can be temporarily taken offline to quickly restore production.

[0025] 2. The length of the rolling groove is extended, the efficiency is improved, and the cost is reduced.

[0026] 3. The finished product size is stable, meets the requirements of customers and national standards, and has no stress cracks at the corner. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a schematic diagram of the cross-sectional size of the spring flat steel in the present application;

[0028] Figure 2 It is a size diagram of the K4 pass in the present application;

[0029] Figure 3 It is a size diagram of the K2 pass in the present application;

[0030] Figure 4 It is a physical picture of the finished product of the rectangular flat steel without corresponding defects after optimization of R angle, size and corner parameters in the embodiment of the present application;

[0031] Figure 5 It is a physical picture of the rectangular flat steel product obtained by the prior art, and the R angle design is unreasonable, the groove bottom design is unreasonable, which causes the rolling groove surface to be concave, the groove bottom to be convex, and affects the surface quality of the finished product;

[0032] Figure 6 Figure for the unreasonable reduction in the prior art leading to broken roll;

[0033] Figure 7 Figure for the finished product with unreasonable parameter design leading to torsion and surface folding. DETAILED DESCRIPTION

[0034] The application will be further described in conjunction with specific examples and drawings.

[0035] Example 1: 40mm x 100mm rectangular flat steel rolling

[0036] The 40mm x 100mm rectangular flat steel rolling method of the present embodiment has the following specific process parameters:

[0037] 1) The semi-finished product round diameter is 106mm;

[0038] 2) The rectangular rolling system adopts the mode of flat roll 5-flat roll 4-K4-flat roll 3-flat roll 2-K2-flat roll 1, wherein K4 and K2 are special hole patterns for 40mm x 100mm rectangular flat steel;

[0039] 3) The reduction of flat roll 5 is 40mm, the reduction of flat roll 4 is 20mm, the reduction of K4 is 22.5mm, the reduction of flat roll 3 is 5.25mm, the reduction of flat roll 2 is 6.6mm, the reduction of K2 is 15.22mm, and the reduction of flat roll 1 is 4mm;

[0040] 4) The corresponding mill guide opening of flat roll 5, flat roll 4, flat roll 3 and flat roll 2 is 6mm larger than the material type; the corresponding mill guide opening of K4, K2 and flat roll 1 is 2mm larger than the material type;

[0041] 5) To ensure the stability of the rolled piece in the mill train, the guide roll hole pattern in step 4) is specified, the guide roll R of flat roll 5 and flat roll 4 is 44mm, and the guide roll R of flat roll 3 and flat roll 2 is 40mm;

[0042] 6) Among them, the slot width (B) of K4 is designed as 72mm, the slot bottom width (b) is designed as 63mm, the slot bottom corner R of K4 hole pattern is designed as 18mm, the slot opening corner r is designed as 10mm, the side wall slope is designed as 6°, and the slot depth (H) is designed as 43mm. The slot width (B) of K2 is designed as 40.5mm, the slot bottom width (b) is designed as 45mm, the slot bottom corner R of K2 hole pattern is designed as 12mm, the slot opening corner r is designed as 10mm, the side wall slope is designed as 4°, and the slot depth (H) is designed as 40mm.

[0043] The 40mm x 100mm rectangular flat steel rolling parameters of the present embodiment are shown in Table 1 below:

[0044] ;

[0045] Advantages of the present application:

[0046] 1. The rectangular rolling system adopts the mode of flat roller 5-flat roller 4-K4-flat roller 3-flat roller 2-K2-flat roller 1. If any one of the flat roller 5, the flat roller 4, the flat roller 3 and the flat roller 2 corresponding to any one of the rolling mills fails, it can be temporarily taken offline to quickly restore production.

[0047] 2. The length of the rolling groove is extended to increase the steel passing capacity, improve the efficiency and reduce the cost.

[0048] 3. The finished product size is stable, meets the requirements of customers and national standards, and has no stress cracks at the corners.

Claims

1. A method of rolling a 40 mm x 100 mm rectangular flat steel, characterized by, The specific process parameters are as follows: 1) the semi-finished product has a diameter of 100-110 mm; 2) the rectangular rolling system adopts a mode of flat roller 5-flat roller 4-K4-flat roller 3-flat roller 2-K2-flat roller 1, wherein K4 and K2 are special hole patterns for 40 mm*100 mm rectangular flat steel; 3) the reduction of flat roller 5 is 36-45 mm, the reduction of flat roller 4 is 15-25 mm, the reduction of K4 is 18-24 mm, the reduction of flat roller 3 is 5-8 mm, the reduction of flat roller 2 is 6-8 mm, the reduction of K2 is 10-16 mm, and the reduction of flat roller 1 is 3-5 mm; 4) the corresponding mill guide opening of flat roller 5, flat roller 4, flat roller 3 and flat roller 2 is 5-8 mm larger than the material type, and the corresponding mill guide opening of K4, K2 and flat roller 1 is 1-3 mm larger than the material type; 5) in order to ensure the stability of the rolled piece in the mill train, the guide roller hole pattern in step 4) is specified, the guide roller R of flat roller 5 and flat roller 4 is 42-46 mm, and the guide roller R of flat roller 3 and flat roller 2 is 38-42 mm; 6) wherein the design K4 slot width is 70-74 mm, the slot bottom width is 62-65 mm, the K4 hole pattern slot bottom corner R angle radius is 17-19 mm, the slot opening corner r angle radius is 9-12 mm, the side wall slope is 5-8°, and the slot depth is 42-46 mm; the design K2 slot width is 40-41.5 mm, the slot bottom width is 44-46 mm, the K2 hole pattern slot bottom corner R angle radius is 10-12 mm, the slot opening corner r angle radius is 9-12 mm, the side wall slope is 3-5°, and the slot depth is 38-40 mm.

2. The 40 mm x 100 mm rectangular flat steel rolling method according to claim 1, characterized by, The rectangular flat steel error control is 40±0.5 mm and 100±10 mm.

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