Hole pattern structure of hot-rolled 350 Z-shaped steel and rolling method
By optimizing the die structure and rolling method, the problems of low dimensional accuracy and easy cracking at the edges of traditional hot-rolled Z-shaped steel have been solved, improving forming quality and production efficiency, and achieving savings in fuel and electricity.
Patent Information
- Application Number
- CN202511226921.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-29
- Publication Date
- 2025-11-14
AI Technical Summary
Traditional hot-rolled Z-shaped steel has problems such as low dimensional accuracy, high residual stress, and easy cracking at the edges, which affect the forming quality and service life.
By employing optimized pass structures and rolling methods, and through specific pass designs for the S4, S5, and S6 finishing mills, combined with a '1+1+7' process layout, including multi-pass rolling in the billet and finishing stages, and using a 'four-roll - closed-bottom-opening - closed-top-opening' pass system, rolling parameters are precisely controlled to improve forming quality.
It improves the forming quality and material utilization of Z-shaped steel, shortens production time, saves fuel and electricity consumption, reduces roll consumption, and improves the dimensional accuracy and surface quality of products.
Smart Images
Figure CN120940371A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of steel rolling technology, and particularly relates to a roll pass structure and rolling method for hot-rolled 350 Z-shaped steel. Background Technology
[0002] Z-shaped steel, also known as "Z-type steel," is a type of steel with a cross-sectional shape resembling the letter "Z." It is widely used in supporting structures in construction, bridges, and shipbuilding. However, traditional hot-rolled Z-shaped steel suffers from several problems that urgently need to be addressed. These include low dimensional accuracy, leading to poor fit during installation and use in construction and other fields; high residual stress, making the steel prone to deformation and even fracture during use; and easy edge cracking, severely affecting the quality and service life of the steel. To solve these problems, this invention proposes an optimized die structure and rolling method for hot-rolling 350mm Z-shaped steel, aiming to improve forming quality, rolling efficiency, and material utilization. Summary of the Invention
[0003] This invention proposes a die structure and rolling method for hot-rolled 350 Z-shaped steel, which solves the problems of low dimensional accuracy, high residual stress, and easy cracking at the edges in the production process of traditional hot-rolled Z-shaped steel. By optimizing the die design, the forming quality of Z-shaped steel is improved, the rolling efficiency is increased, and the material utilization rate is improved.
[0004] To achieve the above objectives, the present invention employs the following technical solution:
[0005] A roll pass structure for hot-rolled 350 Z-shaped steel is disclosed. The roll passes of finishing mills S4, S5, and S6 all feature a wide flange section, a web section, and a narrow flange section. A right-angled apex is formed between the wide flange section and the web section, and a right-angled apex is formed between the web section and the narrow flange section. The vertical distance between the two right-angled apexes is 145.5 mm. The centerline of the vertical distance between the two right-angled apexes serves as the center reference line of the roll gap. Both endpoints of the roll gap lie on this center reference line. The centerline length of the wide flange section is C1, where C1 is the hot dimension of the 350 Z-shaped steel. The centerline length of the wide flange and the centerline length of the narrow flange section are both C3, where C3 is the centerline length of the narrow flange in the hot-dip size of the 350 Z-beam. The centerline length of the web in the hot-dip size of the 350 Z-beam is C2 = C1 + C3 + C4. The web section = wide flange section + horizontal section + narrow flange section. The centerline length of the horizontal section of the S4 rolling mill pass is C4 - 1mm; the centerline length of the horizontal section of the S5 rolling mill pass is C4 - 0.5mm; and the centerline length of the horizontal section of the S6 rolling mill pass is C4. The thickness of the wide flange section and the web section are the same.
[0006] In the roll pass of S4, S5, and S6 rolling mills, the wide flange section is composed of a horizontal section and a sharp right-angled side, with a rounded transition between the horizontal section and the sharp right-angled side. The horizontal section is on the center reference line. The narrow flange section is also composed of a horizontal section and a sharp right-angled side, with a rounded transition between the horizontal section and the sharp right-angled side. The horizontal section is on the center reference line.
[0007] The S4 rolling mill uses a four-roll pass system, and the straight-line distance between the two ends of the pass is 604.5 mm.
[0008] The S5 mill pass adopts a closed-end, open-side pass system, and the straight-line distance between the two endpoints of the pass is 605mm.
[0009] The S6 mill pass adopts a closed-end, top-opening pass system, and the straight-line distance between the two endpoints of the pass is 605.5 mm.
[0010] The vertical distance between the two right-angled apexes of the finished 350 Z-shaped steel die is 190mm, the wide flange section C1 = 182, the narrow flange section C3 = 120.5, and the web section length is 339.
[0011] A method for rolling hot-rolled 350 Z-shaped steel using a roll pass structure, the specific method including:
[0012] The process layout adopts a "1+1+7" structure. In the billet opening stage, the billet is rolled in 6 passes by BD1 and BD2 mills, including 2 passes of vertical rolling and 4 passes of horizontal rolling with extended pass. When the billet enters the 4th pass of the finishing mill, the iron mold reaches the required size. The first 3 stands (S1, S2, S3) of the finishing mill adopt the traditional pass. The 4th to 6th passes (S4, S5, S6) of the finishing mill adopt the "four-roll - closed lower edge - closed upper edge" pass system for rolling. The finished pass of the 7th stand (S7) is determined according to the hot dimensions. Considering the tolerance range, the thickness is taken as the standard value.
[0013] The rolling parameters for passes 4-6 of the finishing mill are as follows: S4 mill: wide flange elongation coefficient 1.10, reduction 1.30mm; narrow flange elongation coefficient 1.10, reduction 2.00mm; S5 mill: wide flange elongation coefficient 1.03, reduction 0.40mm; narrow flange elongation coefficient 1.03, reduction 0.60mm; S6 mill: wide flange elongation coefficient 1.03, reduction 0.40mm; narrow flange elongation coefficient 1.03, reduction 0.60mm.
[0014] The elongation coefficient for the S1 pass of the finishing mill is 1.25, with a reduction of 5.00 mm at the wide flange end and 7.50 mm at the narrow flange end; the elongation coefficient for the S2 pass is 1.18, with a reduction of 3.00 mm at the wide flange end and 4.50 mm at the narrow flange end; and the elongation coefficient for the S3 pass is 1.17, with a reduction of 2.50 mm at the wide flange end and 3.70 mm at the narrow flange end. Through these three rolling passes, the billet's microstructure is further refined under the influence of the traditional pass system, laying the foundation for subsequent precision rolling using a new pass system.
[0015] The finishing S7 mill is a finished product pass. The dimensions of this pass are precisely determined based on the hot dimensions, while fully considering the product's tolerance range. The thickness is taken as a standard value. Specifically, the thickness of the wide flange plate is 12.00 mm, the thickness of the narrow flange plate is 18.00 mm, the elongation coefficient is 1.03, the reduction of the wide flange is 0.40 mm, and the reduction of the narrow flange is 0.60 mm, to ensure that the final 350 mm specification Z-shaped steel products meet the quality standards.
[0016] Compared with the prior art, the beneficial effects of the present invention are:
[0017] 1) The height of the top of the 4th to 6th holes of the finishing mill is reduced from 190mm to 145.5mm, which reduces the thickness of the billet and can significantly shorten the billet heating time. In addition to saving fuel significantly, it can also effectively control the heating temperature and speed up the production pace.
[0018] 2) After reducing the height of the top of the 4th to 6th holes of the finishing mill, the groove depth of the rolls becomes smaller, which can significantly save roll consumption.
[0019] 3) The horizontal section of the 4-6 hole structure of the finishing mill has a large proportion, which can effectively reduce the axial force of rolling, save power consumption and help improve the dimensional accuracy of the product.
[0020] 4) The “four-roll-closed bottom opening-closed top opening” die system can effectively process the flange ends. For weathering steel materials, it can effectively make up for casting defects and improve the surface quality of the finished product. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the roll gap structure of the S4 mill in the finishing mill unit of this invention.
[0022] Figure 2 This is a schematic diagram of the roll gap structure of the S5 mill in the finishing mill unit of this invention.
[0023] Figure 3 This is a schematic diagram of the roll gap structure of the S6 mill in the finishing mill unit of this invention.
[0024] Figure 4This is a schematic diagram of the roll gap structure of the S7 mill in the finishing mill unit of this invention.
[0025] Figure 5 This is a schematic diagram of the hot-rolled 350 Z-shaped steel in this invention.
[0026] In the diagram: 1-upper roller, 2-one-side vertical roller, 3-lower roller, 4-other-side vertical roller, 5-wide flange section, 6-web section, 7-narrow flange section, 8-wide flange, 9-web, 10-narrow flange. Detailed Implementation
[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. In the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.
[0028] A roll pass structure for hot-rolled 350 Z-shaped steel is disclosed. The roll passes of finishing mills S4, S5, and S6 all feature a wide flange section 5, a web section 6, and a narrow flange section 7. A right-angled apex is formed between the wide flange section 5 and the web section 6, and a right-angled apex is formed between the web section 6 and the narrow flange section 7. The vertical distance between the two right-angled apex is 145.5 mm. The centerline of the vertical distance between the two right-angled apex is the center reference line of the roll gap, and both endpoints of the roll gap are on the center reference line. The centerline length of the wide flange section 5 is equal to C1, where C1 is the width of the hot-rolled 350 Z-shaped steel. The centerline length of flange 8, the centerline length of narrow flange segment 7 = C3, C3 is the centerline length of the hot-size narrow flange 10 of 350 Z-shaped steel, the centerline length of the hot-size web 9 of 350 Z-shaped steel C2 = C1 + C3 + C4, the web segment 6 = wide flange segment 5 + horizontal segment + narrow flange segment 7, wherein the centerline length of the horizontal segment of the S4 rolling mill pass = C4 - 1mm; the centerline length of the horizontal segment of the S5 rolling mill pass = C4 - 0.5mm; the centerline length of the horizontal segment of the S6 rolling mill pass = C4; the thickness of the wide flange segment 5 is the same as that of the web segment 6.
[0029] In the roll pass of S4, S5, and S6 mills, the wide flange section 5 is composed of a horizontal section and a sharp right-angled side, with a rounded transition between the horizontal section and the sharp right-angled side. The horizontal section is on the center reference line. The narrow flange section 7 is also composed of a horizontal section and a sharp right-angled side, with a rounded transition between the horizontal section and the sharp right-angled side. The horizontal section is on the center reference line.
[0030] The S4 rolling mill uses a four-roll pass system, and the straight-line distance between the two ends of the pass is 604.5 mm.
[0031] The S5 mill pass adopts a closed-end, open-side pass system, and the straight-line distance between the two endpoints of the pass is 605mm.
[0032] The S6 mill pass adopts a closed-end, top-opening pass system, and the straight-line distance between the two endpoints of the pass is 605.5 mm.
[0033] The vertical distance between the two right-angled apexes of the 350 Z-shaped steel finished product profile (S7 rolling mill profile) is 190mm, the wide flange section C1 = 182, the narrow flange section C3 = 120.5, and the web section length is 339.
[0034] A method for rolling hot-rolled 350 Z-shaped steel using a roll pass structure, the specific method including:
[0035] This invention employs a unique "1+1+7" process layout, and its specific structure and working principle are as follows:
[0036] Overall Layout: This roll pass system consists of a roughing stage and a finishing stage. The roughing stage is conducted collaboratively by mills BD1 and BD2, rolling a 650×200mm billet in six passes. These six passes include two vertical rolling passes, primarily used for preliminary shaping of the billet's width, adjusting its shape to more closely resemble the desired form for subsequent rolling. Simultaneously, four horizontal rolling extension passes are provided, gradually increasing the billet's length and reducing its thickness through the horizontal rolling process, preparing it for the finishing stage. When the billet enters the fourth finishing pass, it must be ensured that the die meets the predetermined dimensional requirements.
[0037] The finishing rolling stage includes 7 mill stands (S1-S7). The first 3 stands (S1-S3) use traditional pass patterns. The 4th to 6th passes (S4, S5, S6) of the finishing mill use a specific pass pattern of "four rolls - closed bottom edge - closed top edge". The finished pass pattern of the 7th stand (S7) is determined according to the hot dimensions. Considering the tolerance range, the thickness is taken as the standard value.
[0038] Initial conventional pass rolling: The first three stands of the finishing mill, namely S1, S2, and S3, are rolled using conventional passes. Because the billet temperature is high and the material has good plasticity at this stage, based on actual production experience, the elongation coefficient for the S1 pass is 1.25, with a reduction of 5.00 mm at the wide flange end and 7.50 mm at the narrow flange end; the elongation coefficient for the S2 pass is 1.18, with a reduction of 3.00 mm at the wide flange end and 4.50 mm at the narrow flange end; and the elongation coefficient for the S3 pass is 1.17, with a reduction of 2.50 mm at the wide flange end and 3.70 mm at the narrow flange end. Through these three passes, the billet's microstructure is further refined under the influence of the conventional passes, laying the foundation for subsequent precision rolling using a new pass system.
[0039] New roll pass system: Starting from the 4th stand of the finishing mill, namely the S4 mill, and continuing to the 6th stand, namely the S6 mill, the "four-roll - closed bottom opening - closed top opening" roll pass system is used for rolling.
[0040] The rolling parameters for passes 4-6 of the finishing mill are as follows: For the S4 mill pass, the wide flange end plate thickness is 13.20 mm, the elongation coefficient is 1.10, and the reduction is 1.30 mm; the narrow flange end plate thickness is 19.80 mm, the elongation coefficient is 1.10, and the reduction is 2.00 mm, making it a four-roll pass; for the S5 mill pass, the wide flange end plate thickness is 12.80 mm, the elongation coefficient is 1.03, and the reduction is 0. 40mm; the narrow flange end plate thickness is 19.20mm, the elongation coefficient is 1.03, the reduction is 0.60mm, and it is a bottom open-edge closed pass type; the S6 mill pass type has a wide flange end plate thickness of 12.40mm, an elongation coefficient of 1.03, and a reduction of 0.40mm; the narrow flange end plate thickness is 18.60mm, the elongation coefficient is 1.03, the reduction is 0.60mm, and it is an upper open-edge closed pass type.
[0041] The finishing S7 mill is a finished product pass. The dimensions of this pass are precisely determined based on the hot dimensions, while fully considering the product's tolerance range. The thickness is taken as a standard value. Specifically, the thickness of the wide flange plate is 12.00 mm, the thickness of the narrow flange plate is 18.00 mm, the elongation coefficient is 1.03, the reduction of the wide flange is 0.40 mm, and the reduction of the narrow flange is 0.60 mm, to ensure that the final 350 mm specification Z-shaped steel products meet the quality standards.
[0042] The S4-S6 mill pass profile of this invention reduces the billet apex height from 190.0 mm to 145.5 mm, greatly reducing the billet thickness, significantly shortening the billet heating time, more effectively controlling the heating temperature, accelerating the production pace, reducing the grooving depth of the rolls, and significantly saving roll consumption.
[0043] The horizontal section accounts for a large proportion of the die structure of this invention, which effectively reduces the axial force during rolling, saves power consumption, and improves the dimensional accuracy of the product.
[0044] The "four-roll-closed bottom opening-closed top opening" die system can effectively process the flange ends. For weathering steel, it can effectively compensate for casting defects and improve the surface quality of the finished product.
[0045] See Figure 4 , Figure 5 The present invention provides a hot-dip dimensional drawing for the S7 mill pass design. The dimensions of the transition from S4-S6 passes to the finished pass design all meet the requirements of the hot-dip dimensional drawing.
[0046] In summary, the 1+1+7 process layout adopted in this invention effectively solves the problems of low dimensional accuracy, high residual stress, and easy cracking at the edges of traditional hot-rolled Z-shaped steel. The new die structure adopted in the hot rolling process effectively reduces the height of the billet apex. The hot rolling die of this invention is suitable for the hot rolling of 350 Z-shaped steel and can improve the forming quality of Z-shaped steel.
[0047] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A die structure for hot-rolled 350 Z-shaped steel, characterized in that, The finishing mills S4, S5, and S6 all have roll passes with wide flange sections, web sections, and narrow flange sections. The wide flange section and web section form a right-angled apex, as does the narrow flange section. The vertical distance between the two right-angled apex is 145.5 mm. The centerline of this vertical distance serves as the center reference line for the roll gap, with both endpoints of the roll gap located on this center reference line. The centerline length of the wide flange section is equal to C1, where C1 is the centerline length of the wide flange of the hot-rolled 350 Z-beam. The centerline length of the narrow flange section is C3, where C3 is the centerline length of the narrow flange of the hot-dip 350 Z-beam. The centerline length of the web of the hot-dip 350 Z-beam is C2 = C1 + C3 + C4. The web section = wide flange section + horizontal section + narrow flange section. The centerline length of the horizontal section of the S4 rolling mill pass is C4 - 1mm; the centerline length of the horizontal section of the S5 rolling mill pass is C4 - 0.5mm; and the centerline length of the horizontal section of the S6 rolling mill pass is C4. The thickness of the wide flange section is the same as that of the web section.
2. The die structure of a hot-rolled 350 Z-shaped steel according to claim 1, characterized in that, In the roll pass of S4, S5, and S6 rolling mills, the wide flange section is composed of a horizontal section and a sharp right-angled side, with a rounded transition between the horizontal section and the sharp right-angled side. The horizontal section is on the center reference line. The narrow flange section is also composed of a horizontal section and a sharp right-angled side, with a rounded transition between the horizontal section and the sharp right-angled side. The horizontal section is on the center reference line.
3. The die structure for a hot-rolled 350 Z-shaped steel according to claim 1 or 2, characterized in that, The S4 rolling mill uses a four-roll pass system, and the straight-line distance between the two ends of the pass is 604.5 mm.
4. The die structure of a hot-rolled 350 Z-shaped steel according to claim 1 or 2, characterized in that, The S5 mill pass adopts a closed-end, open-side pass system, and the straight-line distance between the two endpoints of the pass is 605mm.
5. The die structure of a hot-rolled 350 Z-shaped steel according to claim 1 or 2, characterized in that, The S6 mill pass adopts a closed-end open-edge pass system, and the straight-line distance between the two endpoints of the pass is 605.5 mm.
6. The die structure for hot-rolled 350 Z-shaped steel according to claim 1, characterized in that, The vertical distance between the two right-angled apexes of the finished 350 Z-shaped steel die is 190mm, the wide flange section C1 = 182, the narrow flange section C3 = 120.5, and the web section length is 339.
7. A method for rolling hot-rolled 350 Z-shaped steel using the roll pass structure as described in any one of claims 1-6, characterized in that, Specific methods include: The rolling parameters for passes 4-6 of the finishing mill are as follows: S4 mill: wide flange elongation coefficient 1.10, reduction 1.30mm; narrow flange elongation coefficient 1.10, reduction 2.00mm; S5 mill: wide flange elongation coefficient 1.03, reduction 0.40mm; narrow flange elongation coefficient 1.03, reduction 0.60mm; S6 mill: wide flange elongation coefficient 1.03, reduction 0.40mm; narrow flange elongation coefficient 1.03, reduction 0.60mm.
8. A method for rolling hot-rolled 350 Z-shaped steel using a roll pass structure according to claim 7, characterized in that, For the finishing mill S1 pass, the elongation coefficient is 1.25, and the reduction is 5.00 mm at the wide flange end and 7.50 mm at the narrow flange end; for the S2 pass, the elongation coefficient is 1.18, and the reduction is 3.00 mm at the wide flange end and 4.50 mm at the narrow flange end; for the S3 pass, the elongation coefficient is 1.17, and the reduction is 2.50 mm at the wide flange end and 3.70 mm at the narrow flange end.
9. A method for rolling hot-rolled 350 Z-shaped steel using a roll pass structure according to claim 7, characterized in that, The finishing mill S7 has a finished product roll pass with an elongation coefficient of 1.03, a reduction of 0.40 mm at the wide flange end, and a reduction of 0.60 mm at the narrow flange end.