A single-sided double-groove flat steel and its rolling production process

Abstract

This invention relates to a single-sided double-groove flat steel and its rolling production process. Specifically, it involves designing a rolling process for producing flat steel with two parallel grooves on a single side on an existing round steel rolling production line. Through optimized pass design and rolling flow, a square billet is continuously rolled in multiple passes, including primary rolling, intermediate rolling, and finishing rolling, for hot rolling production. The finishing mill includes at least one double-groove rolling mill with a special roll type. Using this double-groove rolling mill, two parallel grooves with preset depths and widths are simultaneously formed on a single surface of the intermediate billet through one or multiple consecutive rolling passes, thereby significantly improving production efficiency and product precision.

Description

Technical Field

[0001] This invention relates to a single-sided double-groove flat steel and its rolling production process, belonging to the technical field of metal pressure processing. Background Technology

[0002] Flat steel, a common type of steel profile, is widely used in various fields such as machinery manufacturing, construction, and automobiles. In certain specific applications, it is necessary to machine grooves into the surface of flat steel, such as for installing sealing strips, serving as guide grooves, or reducing weight. Traditional processing methods primarily involve creating grooves on finished flat steel through machining processes such as milling and planing. This method suffers from low material utilization, low processing efficiency, and high costs. Furthermore, the cutting process disrupts the metal flow lines, reducing the fatigue strength of the parts.

[0003] To overcome the drawbacks of machining, existing technologies have also developed processes for directly forming grooved flat steel through rolling. However, most of these processes employ a single-groove successive rolling method, that is, rolling out one groove first, then adjusting the position to roll out another groove. This method results in a slow production pace, requires high precision in mill adjustment, and makes it difficult to guarantee the symmetry and dimensional consistency between the two grooves, leading to low production efficiency.

[0004] Therefore, there is an urgent need for a new rolling process that can produce single-sided double-groove flat steel efficiently, with high precision and low cost. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a single-sided double-groove flat steel and its rolling production process, the specific technical solution of which is as follows: A rolling process for single-sided double-groove flat steel includes the following steps: Step S1: Material preparation: Provide a blank with a square cross-section of 150mm × 150mm; Step S2: Heating: The billet prepared in step S1 is heated to the rolling temperature in a heating furnace. The heating furnace includes a first heating section, a second heating section, and a soaking section. The temperature of the first heating section is 770-840℃, the temperature of the second heating section is 960-1010℃, and the temperature of the soaking section is 1030-1060℃. The total time for the billet in the heating furnace is 90-130 min. Step S3: Rough rolling and intermediate rolling: The billet heated in step S2 is sequentially fed into the rough rolling mill and intermediate rolling mill for multiple rolling passes, so that its thickness reaches the preset base thickness and width of the flat steel intermediate billet. Step S4: Finishing: The flat steel intermediate billet after roughing and intermediate rolling in step S3 is introduced into the finishing mill. The finishing mill includes at least one double-groove rolling mill with a preset roll type. The double-groove rolling mill is used to roll the flat steel intermediate billet in one pass or multiple passes to form two parallel grooves with preset depth and width. Step S5: Cooling: The rolled single-sided double-groove flat steel is fed into a cooling bed for controlled cooling; Step S6: Cutting to length and collecting: Cut the cooled single-sided double-groove flat steel to length and collect it as finished product.

[0006] Furthermore, the double-groove rolling mill in step S4 includes an upper rolling mill and a lower rolling mill. The lower rolling mill is a rolling mill with a flat groove. The working surface of the upper rolling mill is provided with two concentric, raised rolling rings. A central groove is formed between the two rolling rings, and a flat groove is formed between the two rolling rings and their respective outer sides. When the flat steel intermediate billet passes between the upper and lower rolls, the two protruding rolling rings of the upper roll roll two grooves on the upper surface of the flat steel intermediate billet, while the lower roll with flat grooves ensures that the lower surface of the finished flat steel is flat.

[0007] Furthermore, the width and height of the two raised rolling rings on the upper roll, as well as the spacing between the two rolling rings, are consistent with the specifications of the grooves required on the finished single-sided double-groove flat steel.

[0008] Furthermore, one or more pre-rolling mills are provided between the intermediate rolling mill and the finishing rolling mill. After step S3 and before step S4, the flat steel intermediate billet enters the pre-rolling mill. Each pre-rolling mill includes an upper pre-roll and a lower pre-roll. The lower pre-roll is a flat roll. The working surface of the upper pre-roll has two concentric, raised pre-rolling rings, and a central groove is formed between the two pre-rolling rings.

[0009] Furthermore, when the pre-rolling mill has multiple stands, from upstream to downstream of the pre-rolling mill, the depth and width of the pre-rolling ring of the upper pre-rolling roll gradually increase, and none of them are greater than the specifications of the groove required on the finished single-sided double-groove flat steel. The distance between the two pre-rolling rings of the upper pre-rolling roll is consistent with the distance between the two grooves on the finished single-sided double-groove flat steel.

[0010] Furthermore, in step S4, the groove depth of the finishing mill is 20% to 50% of the base thickness of the flat steel intermediate billet obtained in step S3.

[0011] Furthermore, a dedicated finished product frame guide is installed upstream of the twin-groove rolling mill. This dedicated guide includes multiple sets of guide wheels and guide plates distributed vertically, horizontally, and vertically, forming a positioning channel that connects to the rolling mill pass of the twin-groove rolling mill. The guide wheels and guide plates control the precise position of the hot strip entering the rolling mill pass of the twin-groove rolling mill, preventing deviation and instability, and ensuring that the hot strip (the flat steel intermediate billet after step S2) accurately enters the rolling mill pass.

[0012] Furthermore, the controlled cooling in step S5 adopts a slow cooling process with a cooling rate of no more than 10°C / s.

[0013] Furthermore, after step S2 is completed and before step S3 is started, high-pressure water descaling is also included, in which the billet passes through an annular high-pressure water descaling device with a water pressure ≥25MPa.

[0014] A single-sided double-groove flat steel produced according to the above-mentioned rolling process, wherein one surface of the single-sided double-groove flat steel has two grooves of the same size and parallel distribution, and the area between the two grooves is flush with the area from the grooves to the edge of the single-sided double-groove flat steel.

[0015] The beneficial effects of this invention are: This invention enables the simultaneous rolling of two precisely sized and symmetrically positioned grooves on a single surface of a flat steel bar in a single operation, thereby significantly improving production efficiency and product precision. Specifically: 1. High efficiency: Through a special double-groove rolling mill, the two grooves are rolled synchronously in one go, which increases production efficiency by more than 50% compared with traditional sequential rolling or machining.

[0016] 2. High precision and consistency: Since the two grooves are formed in the same set of rollers and in the same pass, the spacing, depth and shape between them are very consistent and symmetrical, resulting in high product dimensional accuracy.

[0017] 3. Low cost: It eliminates subsequent machining processes, reduces equipment investment and energy consumption, improves material utilization, and significantly reduces production costs.

[0018] 4. Superior performance: The rolled grooves retain the complete metal flow lines and do not have the cutting effect caused by machining, so the product has better fatigue strength and mechanical properties.

[0019] 5. Flexibility: By changing the double-groove rolls of different specifications, it is possible to flexibly produce single-sided double-groove flat steel of various specifications with different groove spacing, groove depth and groove width, which is highly adaptable. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the rolling production process of the present invention. Figure 2 This is a schematic diagram of the double-groove finished roll profile of the present invention. Figure 3 This is a schematic diagram of the special imported guide for the double-slot finished product frame of the present invention. Figure 4 This is a cross-sectional schematic diagram of a single-sided double-groove flat steel produced by the process of this invention. Figure 5 This is a photograph of a single-sided double-groove flat steel produced using the process of this invention. Detailed Implementation

[0021] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] The main applicable steel type for this invention is spring steel 60Si2Mn, which has special shape requirements.

[0023] Considering that multi-pass rolling to form grooves would require high positional accuracy of the hot strips, otherwise misalignment and scrapping would occur, the optimal choice for this invention is a single-pass double-groove rolling mill, with groove depth suitable for single-pass forming. The steel rolling speed exceeds 10 meters per second, resulting in a very short point-contact time.

[0024] The following is a specific implementation of the present invention: Produce a single-sided double-groove flat steel with a base thickness of 13mm, a width of 89mm, and two grooves with a depth of 6mm, a width of 15mm, and a spacing of 30mm.

[0025] S1: Material preparation: Select 150mm×150mm continuous casting square billets, and use them as billets after the composition is inspected and found to be qualified.

[0026] S2: Heating: The billet is fed into a walking beam furnace and heated to a rolling temperature of 1045±15℃, and held for a period of time to make the internal and external temperatures uniform.

[0027] S3: High-pressure water descaling: The billet passes through an annular high-pressure water descaling device with a water pressure ≥25MPa.

[0028] S4: Roughing + Intermediate Rolling: The billet is rolled in 8 passes on a φ550×4 roughing mill and a φ550×4 intermediate mill to produce intermediate flat bars with a thickness of 36mm and a width of 100mm. The ends of the intermediate flat bars are sheared off by a flying shear to ensure the quality of the ends of the intermediate flat bars entering the finishing mill. Roughing + intermediate rolling mainly provides intermediate rectangular stock; the reduction in roughing and intermediate rolling is greater to improve core quality.

[0029] S5: Finishing Rolling: The intermediate flat steel is fed into the finishing rolling mill. The finishing rolling mill includes a specially designed double-groove mill, also known as the finished product grooving stand. The groove pattern of the finished product grooving stand is pre-set in the machining plant, essentially acting as a mold. See details... Figure 2 The lower roll of the double-groove rolling mill is a smooth flat roll, while the upper roll has two raised rolling rings, each 6.5 mm high and 15.7 mm wide at the bottom (considering thermal expansion and springback). The center-to-center distance between the two rings is 45.7 mm. The intermediate billet passes through this double-groove rolling mill, where two compliant grooves are rolled into its upper surface in a single pass, while the lower surface remains flat. After exiting the finishing stand, the hot strips (flat steel after the grooves have been rolled into the intermediate billet) are cut into multiple lengths of 80-100 m using a multiple-length flying shear to meet the length requirements for the cooling bed. The hot strips are formed at temperatures above 950℃, keeping the steel in the austenitic region with good plasticity. The rolling process causes recovery and recrystallization, eliminating stress caused by deformation.

[0030] S6: Cooling: The rolled piece (flat steel of appropriate length with grooves) is transported to the cooling bed for slow cooling. The cooling rate is controlled at about 5℃ / s to ensure that the flat steel is straight and free from warping or deformation.

[0031] S7: Length Setting and Collection: After the steel (flat steel after slow cooling) is placed on the cooling bed, it is cut to the length required by the user using a length cutter, then packaged, weighed, and then lifted into the slow cooling pit by a suction cup. The temperature in the pit is ≥300℃. After cooling to room temperature, it is removed from the pit and placed in the finished product warehouse.

[0032] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0033] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A rolling process for single-sided double-groove flat steel, characterized in that, Includes the following steps: Step S1: Material preparation: Provide a blank with a square cross-section of 150mm × 150mm; Step S2: Heating: The billet prepared in step S1 is heated to the rolling temperature in a heating furnace. The heating furnace includes a first heating section, a second heating section and a soaking section. The temperature of the first heating section is 770-840℃, the temperature of the second heating section is 960-1010℃, and the temperature of the soaking section is 1030-1060℃. The total time for the billet in the heating furnace is 90-130 min. Step S3: Rough rolling and intermediate rolling: The billet heated in step S2 is sequentially fed into the rough rolling mill and intermediate rolling mill for multiple rolling passes, so that its thickness reaches the preset base thickness and width of the flat steel intermediate billet. Step S4: Finishing: The flat steel intermediate billet after roughing and intermediate rolling in step S3 is introduced into the finishing mill. The finishing mill includes at least one double-groove rolling mill with a preset roll type. The double-groove rolling mill is used to roll the flat steel intermediate billet in one pass or multiple passes to form two parallel grooves with preset depth and width. Step S5: Cooling: The rolled single-sided double-groove flat steel is fed into a cooling bed for controlled cooling; Step S6: Cutting to length and collecting: Cut the cooled single-sided double-groove flat steel to length and collect it as finished product.

2. The rolling production process of single-sided double-groove flat steel according to claim 1, characterized in that, The double-groove rolling mill in step S4 includes an upper rolling mill and a lower rolling mill. The lower rolling mill is a rolling mill with a flat groove. The working surface of the upper rolling mill is provided with two concentric, raised rolling rings. A central groove is formed between the two rolling rings, and a flat groove is formed between the two rolling rings and their respective outer sides. When the flat steel intermediate billet passes between the upper and lower rolls, the two protruding rolling rings of the upper roll roll two grooves on the upper surface of the flat steel intermediate billet, while the lower roll with flat grooves ensures that the lower surface of the finished flat steel is flat.

3. The rolling production process of single-sided double-groove flat steel according to claim 1, characterized in that, The width, height, and spacing between the two raised rolling rings on the upper roller are consistent with the specifications of the grooves required on the finished single-sided double-groove flat steel.

4. The rolling production process of single-sided double-groove flat steel according to claim 1, characterized in that, Between the intermediate rolling mill and the finishing rolling mill, there is one or more pre-rolling mills. After step S3 and before step S4, the flat steel intermediate billet enters the pre-rolling mill. Each pre-rolling mill includes an upper pre-roll and a lower pre-roll. The lower pre-roll is a flat roll. The working surface of the upper pre-roll has two concentric, raised pre-rolling rings, and a central groove is formed between the two pre-rolling rings.

5. The rolling production process of single-sided double-groove flat steel according to claim 4, characterized in that, When the pre-rolling mill has multiple stands, from upstream to downstream of the pre-rolling mill, the depth and width of the pre-rolling rings of the upper pre-rolling roll gradually increase, and none of them are greater than the specifications of the grooves required on the finished single-sided double-groove flat steel. The spacing between the two pre-rolling rings of the upper pre-rolling roll is consistent with the spacing between the two grooves on the finished single-sided double-groove flat steel.

6. The rolling production process of single-sided double-groove flat steel according to claim 1, characterized in that, In step S4, the groove depth of the finishing mill is 20% to 50% of the base thickness of the flat steel intermediate billet obtained in step S3.

7. The rolling production process for single-sided double-groove flat steel according to claim 1, characterized in that, A dedicated finished product frame guide is installed upstream of the twin-groove rolling mill. The dedicated finished product frame guide includes multiple sets of guide wheels and guide plates distributed vertically, horizontally, and vertically. A positioning channel is formed between the guide wheels and guide plates, and the positioning channel is connected to the rolling mill hole of the twin-groove rolling mill.

8. The rolling production process of single-sided double-groove flat steel according to claim 1, characterized in that, The controlled cooling in step S5 adopts a slow cooling process with a cooling rate of no more than 10℃ / s.

9. The rolling production process of single-sided double-groove flat steel according to claim 1, characterized in that, After step S2 is completed and before step S3 is started, high-pressure water descaling is also included, in which the billet passes through an annular high-pressure water descaling device with a water pressure ≥25MPa.

10. A single-sided double-groove flat steel produced by the rolling process according to any one of claims 1-9, characterized in that, The single-sided double-groove flat steel has two parallel grooves of the same size on one surface, and the area between the two grooves is flush with the area from the grooves to the edge of the single-sided double-groove flat steel.

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