A pass sequence for hot rolling of 350 angle steel

Abstract

A roll pass structure for hot-rolled 350 Z-shaped steel is disclosed. The S4, S5, and S6 mill passes of the finishing mill all have a wide flange section, a web section, and a narrow flange section. The vertical distance between the two right-angled apexes is 145.5 mm. The centerline length of the wide flange section is C1, where C1 is the centerline length of the wide flange of the 350 Z-shaped steel. The centerline length of the narrow flange section is C3, where C3 is the centerline length of the narrow flange of the 350 Z-shaped steel. The centerline length of the web of the 350 Z-shaped steel is C2 = C1 + C3 + C4. The web section = wide flange section + horizontal section + narrow flange section. Specifically, the centerline length of the horizontal section of the S4 mill pass is C4 - 1 mm; the centerline length of the horizontal section of the S5 mill pass is C4 - 0.5 mm; and the centerline length of the horizontal section of the S6 mill pass is C4. This invention 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, it improves the forming quality of Z-shaped steel, increases rolling efficiency, and improves material utilization.

Description

Technical Field

[0001] This utility model belongs to the field of steel rolling technology, and in particular relates to a die structure 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 cracking at the edges, severely affecting the quality and service life of the steel. To solve these problems, this invention proposes an optimized die structure for hot-rolling 350mm Z-shaped steel, aiming to improve forming quality, rolling efficiency, and material utilization. Utility Model Content

[0003] This invention proposes a die structure 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 adopts 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 open-edge 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] Compared with the prior art, the beneficial effects of this utility model are:

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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

[0016] Figure 1 This is a schematic diagram of the roll gap structure of the S4 mill in the finishing mill unit of this utility model.

[0017] Figure 2 This is a schematic diagram of the roll gap structure of the S5 mill in the finishing mill unit of this utility model.

[0018] Figure 3This is a schematic diagram of the roll gap structure of the S6 mill in the finishing mill unit of this utility model.

[0019] Figure 4 This is a schematic diagram of the roll gap structure of the S7 mill in the finishing mill unit of this utility model.

[0020] Figure 5 This is a schematic diagram of the hot-rolled 350 Z-shaped steel in this utility model.

[0021] 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

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. In the absence of conflict, the embodiments and features in the embodiments of the present utility model can be combined with each other. The present utility model will be described in detail below with reference to the accompanying drawings and embodiments.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] A method for rolling hot-rolled 350 Z-shaped steel using a roll pass structure, the specific method including:

[0030] This utility model adopts a unique "1+1+7" process layout, and its specific structure and working principle are as follows:

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The S4-S6 mill pass profile of this utility model reduces the height of the billet apex from 190.0 mm to 145.5 mm, which greatly reduces the thickness of the billet, significantly shortens the heating time of the billet, more effectively controls the heating temperature, speeds up the production pace, reduces the groove depth of the rolls, and greatly saves the consumption of rolls.

[0038] 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.

[0039] 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.

[0040] See Figure 4 , Figure 5 The hot-difference dimension drawing is used as a reference for the S7 rolling mill pass pattern of this utility model. The dimensions of the pass patterns from S4 to S6, and the finished pass patterns, all meet the requirements of the hot-difference dimension drawing.

[0041] In summary, the 1+1+7 process layout adopted in this utility model 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 utility model is suitable for the hot rolling of 350 Z-shaped steel and can improve the forming quality of Z-shaped steel.

[0042] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A pass sequence for hot rolling a 350 angle steel, characterized by, 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. A pass sequence for hot rolling a 350 angle steel according to claim 1, wherein, 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. A pass sequence for hot rolling of 350 angle 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. A pass sequence for hot rolling of 350 angle 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. A pass sequence for hot rolling of 350 angle steel according to claim 1 or 2, wherein 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.

6. A pass sequence for hot rolling a 350 angle steel according to claim 1, wherein, 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.

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