Steel rail rolling high and low point defect control method

Abstract

The invention relates to a steel rail rolling high and low point defect control method which comprises the following steps: 1) a steel rail rolling production line comprises a first blooming mill, namely a BD1 mill, a second blooming mill, namely a BD2 mill and a universal mill, rough rolling is performed on a steel rail blank through the BD1 mill and the BD2 mill, and finish rolling is performed on the steel rail blank through the universal mill; (2) the universal rolling mill is composed of a universal roughing mill, namely a UR rolling mill, an edging mill, namely an E rolling mill and a universal finishing mill, namely a UF rolling mill which are arranged in sequence, and the steel rail blank is rolled for five passes in the universal rolling mill; and (3) obtaining the finished steel rail after rolling of the universal rolling mill. The five-pass intermittent rolling method is adopted, the finished product pass UF rolling mill and the finished product front pass EF rolling mill are used for independent rolling, high and low point defects of the steel rail can be effectively avoided, the straightness of the finished steel rail is improved, and meanwhile the production speed is increased.

Description

Technical Field

[0001] The invention relates to the technical field of rail rolling, and in particular to a method for controlling high and low point defects in rail rolling. Background Art

[0002] At present, the mainstream rolling method for rails is the universal rolling mill. The main frame of the universal rolling mill consists of a pair of main rollers and a pair of horizontal rollers. The axes of the four rollers are in the same plane. The horizontal rollers are active rollers and the vertical rollers are driven rollers. The four sides of the rolling body can be processed at the same time. When rolling rails by the universal rolling method, two billet rolling mills are used for rough rolling. The basic production process is as follows:

[0003] (1) After heating and descaling, the rectangular continuous casting billet is rolled by the first billet mill (i.e., BD1 mill, usually a two-roller reversible billet mill); (2) The hat-shaped rolling of the first billet mill rolls the billet into a hat-shaped rolled piece and then sends it to the second billet mill (i.e., BD2 mill, usually a two-roller reversible billet mill) for rolling; (3) The rail-shaped hole of the second billet mill rolls the hat-shaped rolled piece into the prototype of the rail, which is then descaled and sent to the universal finishing mill for rolling; (4) After rolling and descaling by the universal finishing mill, it is sent to the universal intermediate rolling mill for rolling. After rolling, the size and shape of the cross-section of the rolled piece are close to those of the finished rail; (5) After rolling by the universal intermediate rolling mill, it is sent to the universal finishing mill for rolling, thus completing the rolling process of the rail.

[0004] Universal rolling mill rolling (finishing rolling) of rails usually adopts three-stand reciprocating three-pass continuous rolling. The first stand is the universal roughing mill, namely the UR mill, the second stand is the edge rolling mill, namely the E mill, and the third stand is the universal finishing mill, namely the UF mill. When three-stand continuous rolling is adopted, due to the tension establishment and release between the mills, when the UF mill is rolling, the UF hole type opens at the corresponding rail head 1 position (such as Figure 1 As shown in the figure, during continuous rolling, the middle position of the tread of the rail head 1 is prone to abnormal rail height, that is, high-low point defects, which are very unfavorable to the control of rail straightness. Such high-low point defects can only be processed by subsequent grinding, which directly affects the production speed and the surface quality of the finished rail. Summary of the invention

[0005] The present invention provides a method for controlling high and low point defects in rail rolling, which adopts a five-pass intermittent rolling method, wherein a UF rolling mill for the finished product pass and an EF rolling mill for the pre-finished product pass are rolled separately, thereby effectively avoiding the generation of high and low point defects in the rail, improving the straightness of the finished rail, and simultaneously increasing the production speed.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for controlling high and low point defects in rail rolling includes the following steps:

[0008] 1) The rail rolling production line includes the first slab mill, namely BD1 mill, the second slab mill, namely BD2 mill, and a universal mill. The BD1 mill and BD2 mill are used to perform rough rolling on the rail billet, and the universal mill is used to perform finish rolling on the rail billet;

[0009] 2) The universal rolling mill is composed of a universal rough rolling mill, namely the UR rolling mill, an edge rolling mill, namely the E rolling mill, and a universal finishing rolling mill, namely the UF rolling mill, which are arranged in sequence. The rail blank is rolled for a total of 5 passes in the universal rolling mill; specifically:

[0010] In the first pass, the UR mill and the E mill are rolling in tandem, and the UF mill is running empty;

[0011] In the first two passes, the E mill and the UR mill are continuous rolling, and the UF mill is empty;

[0012] The UR mill rolls in the third pass, while the E mill and the UF mill run empty;

[0013] The 4th pass is rolled by the E mill, while the UR mill and the UF mill run empty;

[0014] The 5th pass is rolled by the UF mill, while the UR mill and the E mill run empty;

[0015] After rolling by the universal rolling mill, the finished rails are obtained.

[0016] Furthermore, the BD1 rolling mill and the BD2 rolling mill are both two-roller reversible blooming rolling mills.

[0017] Furthermore, the E rolling mill is a two-roll rolling mill, and the UR rolling mill and the UF rolling mill are both four-roll rolling mills.

[0018] Furthermore, the rails are high-speed railway rails.

[0019] Furthermore, the difference between the highest point and the lowest point of the tread of the rail head of the finished steel rail is ≤0.3mm.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The five-pass intermittent rolling method is adopted, and the UF rolling mill for the finished product pass and the EF rolling mill for the pre-finished product pass are rolled separately, which can effectively avoid the generation of high and low point defects of the rail and improve the straightness of the finished rail;

[0022] 2) The straightness of the finished rail meets the standard requirements, and no subsequent grinding is required, which improves the production speed;

[0023] 3) Particularly suitable for production processes that have high requirements on rail straightness (such as high-speed railway rails). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a schematic diagram of the UF hole type when the rail is rolled in the UF rolling mill.

[0025] Figure 2 It is a schematic diagram of five-pass discontinuous rolling of the universal rolling mill according to the present invention.

[0026] In the figure: 1. Rail head DETAILED DESCRIPTION

[0028] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0029] The present invention provides a method for controlling high and low point defects in rail rolling, comprising the following steps:

[0030] 1) The rail rolling production line includes the first slab mill, namely BD1 mill, the second slab mill, namely BD2 mill, and a universal mill. The BD1 mill and BD2 mill are used to perform rough rolling on the rail billet, and the universal mill is used to perform finish rolling on the rail billet;

[0031] 2) If Figure 2 As shown, the universal rolling mill is composed of a universal rough rolling mill, namely, UR rolling mill, an edge rolling mill, namely, E rolling mill, and a universal finishing rolling mill, namely, UF rolling mill, which are arranged in sequence. The rail blank is rolled for a total of 5 passes in the universal rolling mill; specifically:

[0032] In the first pass, the UR mill and the E mill are rolling in tandem, and the UF mill is running empty;

[0033] In the first two passes, the E mill and the UR mill are continuous rolling, and the UF mill is empty;

[0034] The UR mill rolls in the third pass, while the E mill and the UF mill run empty;

[0035] The 4th pass is rolled by the E mill, while the UR mill and the UF mill run empty;

[0036] The 5th pass is rolled by the UF mill, while the UR mill and the E mill run empty;

[0037] After rolling by the universal rolling mill, the finished rails are obtained.

[0038] Furthermore, the BD1 rolling mill and the BD2 rolling mill are both two-roller reversible blooming rolling mills.

[0039] Furthermore, the E rolling mill is a two-roll rolling mill, and the UR rolling mill and the UF rolling mill are both four-roll rolling mills.

[0040] Furthermore, the rails are high-speed railway rails.

[0041] Furthermore, the difference between the highest point and the lowest point of the tread of the rail head of the finished steel rail is ≤0.3mm.

[0042] In the present invention, when the rail blank is finished rolled by three universal rolling mills, the usual three-pass reciprocating continuous rolling is improved to continuous rolling by the first two stands for the first two passes, and one pass by each stand for the last three passes, for a total of five passes.

[0043] like Figure 2 As shown, specifically, in the first pass, the UR mill and the E mill are rolled continuously, and the UF mill is running empty; in the second pass, the E mill and the UR mill are rolled continuously, and the UF mill is running through; in the third pass, only the UR mill is rolled, and the E mill and the UF mill are both running empty; in the fourth pass, only the E mill is rolled, and the UR mill and the UF mill are both running empty; in the fifth pass, only the UF mill is rolled, and the UR mill and the E mill are both running empty. Through five passes of intermittent rolling, the high and low point defects caused by the tension establishment and tension release of the three mills in continuous rolling can be avoided during the final finished product rolling.

[0044] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with examples. The following examples are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the protection scope of the present invention. [Example]

[0045] In this embodiment, the rail rolling production line includes a first slab mill, namely, a BD1 mill, a second slab mill, namely, a BD2 mill, and a universal mill. The BD1 mill and the BD2 mill are used to perform rough rolling on the rail blank, and the universal mill is used to perform finish rolling on the rail blank.

[0046] In this embodiment, the universal rolling mill is composed of a universal rough rolling mill, namely, a UR rolling mill, an edge rolling mill, namely, an E rolling mill, and a universal finishing rolling mill, namely, a UF rolling mill, which are arranged in sequence. The rail blank is rolled for a total of 5 passes in the universal rolling mill; specifically:

[0047] In the first pass, the UR mill and the E mill are rolling in tandem, and the UF mill is running empty;

[0048] In the first two passes, the E mill and the UR mill are continuous rolling, and the UF mill is empty;

[0049] The UR mill rolls in the third pass, while the E mill and the UF mill run empty;

[0050] The 4th pass is rolled by the E mill, while the UR mill and the UF mill run empty;

[0051] The 5th pass is rolled by the UF mill, while the UR mill and the E mill run empty;

[0052] After rolling by the universal rolling mill, the finished rails are obtained.

[0053] In this embodiment, after the universal rolling mill is rolled five times back and forth, a measurement data curve of the high and low points of the rail head tread is obtained. The highest point value in the curve is M=0.07mm, the lowest point value is m=-0.02mm, and the difference between the highest point and the lowest point is 0.09mm.

[0054] [Comparative Example]

[0055] The rail rolling production line used in this comparative example is the same as that in the embodiment, and the composition of the universal rolling mill is also the same as that in the embodiment. The difference is that the universal rolling mill performs three passes in total; specifically:

[0056] In the first pass, the UR mill and the E mill are rolled in tandem, and the UF mill runs empty;

[0057] In the second pass, the E mill and the UR mill are rolled in tandem, and the UF mill runs empty;

[0058] The third pass is continuous rolling of UR mill, E mill and UF mill.

[0059] After rolling by the universal rolling mill, the finished rails are obtained.

[0060] In this comparative example, after three reciprocating passes of rolling, the universal rolling mill obtained a measurement data curve of the high and low points of the rail head tread. The highest point value in the curve is M=0.19mm, the lowest point value is m=-0.29mm, and the difference between the highest point and the lowest point is 0.48mm.

[0061] Conclusion: After adopting the rail rolling high and low point defect control method described in the present invention, the rail high and low point defects are significantly improved.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for controlling high and low point defects in rail rolling, characterized in that: The process includes the following: 1) The rail rolling production line includes the first slab mill, namely BD1 mill, the second slab mill, namely BD2 mill, and a universal mill. The BD1 mill and BD2 mill are used to perform rough rolling on the rail billet, and the universal mill is used to perform finish rolling on the rail billet; 2) The universal rolling mill is composed of a universal rough rolling mill, namely the UR rolling mill, an edge rolling mill, namely the E rolling mill, and a universal finishing rolling mill, namely the UF rolling mill, which are arranged in sequence. The rail blank is rolled for a total of 5 passes in the universal rolling mill; specifically: In the first pass, the UR mill and the E mill are rolling in tandem, and the UF mill is running empty; In the first two passes, the E mill and the UR mill are continuous rolling, and the UF mill is empty; The UR mill rolls in the third pass, while the E mill and the UF mill run empty; The 4th pass is rolled by the E mill, while the UR mill and the UF mill run empty; The 5th pass is rolled by the UF mill, while the UR mill and the E mill run empty; After rolling by the universal rolling mill, the finished rails are obtained.

2. A rail rolling high and low point defect control method according to claim 1, characterized in that: The BD1 rolling mill and the BD2 rolling mill are both two-roller reversible blooming rolling mills.

3. A rail rolling high and low point defect control method according to claim 1, characterized in that: The E rolling mill is a two-roll rolling mill, and the UR rolling mill and the UF rolling mill are both four-roll rolling mills.

4. A rail rolling high and low point defect control method according to claim 1, characterized in that: The steel rails are high-speed railway rails.

5. A rail rolling high and low point defect control method according to claim 1, characterized in that: The difference between the highest point and the lowest point of the tread of the finished rail head is ≤0.3mm.

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