A method for controlling high and low point defects in rail rolling

Abstract

This invention relates to a method for controlling high and low point defects in rail rolling, comprising the following processes: 1) A rail rolling production line includes a first billet mill (BD1), a second billet mill (BD2), and a universal mill. The rail billet is rough-rolled using BD1 and BD2, and then finish-rolled using the universal mill; 2) The universal mill consists of a universal roughing mill (UR), an edge mill (E), and a universal finishing mill (UF), arranged sequentially. The rail billet is rolled five times in the universal mill; 3) After rolling in the universal mill, a finished rail is obtained. This invention employs a five-pass intermittent rolling method, with the finishing pass (UF) and the preceding pass (EF) rolled separately. This effectively avoids high and low point defects in the rail, improves the straightness of the finished rail, and increases production speed.

Description

Technical Field

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

[0002] Currently, the mainstream rolling method for steel rails is the universal rolling mill method. The main frame of the universal rolling mill consists of a pair of main rolls and a pair of horizontal rolls. The axes of the four rolls are in a plane, with the horizontal rolls being the driving rolls and the vertical rolls being the driven rolls, allowing simultaneous processing of all four sides of the rolled material. In the universal rolling method for steel rails, the roughing mill uses a two-stand roughing mill, and its basic production process is as follows:

[0003] (1) After heating and descaling the rectangular continuous casting billet, it is rolled by the first billet rolling mill (i.e., BD1 rolling mill, usually a two-roll reversible billet rolling mill); (2) The first billet rolling mill rolls the billet into a hat-shaped piece and then sends it to the second billet rolling mill (i.e., BD2 rolling mill, usually a two-roll reversible billet rolling mill) for rolling; (3) The second billet rolling mill rolls the hat-shaped piece into the prototype of the rail, and after descaling, it is 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 mill for rolling. The dimensions 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 mill, it is sent to the universal finishing mill for rolling, thus completing the rail rolling process.

[0004] Universal rolling mill (finishing) of rails typically employs a three-stand reciprocating three-pass continuous rolling process. The first stand is a universal roughing mill (UR mill), the second stand is an edge mill (E mill), and the third stand is a universal finishing mill (UF mill). When using three-stand continuous rolling, due to the tension build-up and release between the mills, during UF mill rolling, the UF pass opens at the corresponding rail head position 1 (e.g., ...). Figure 1 As shown, during continuous rolling, abnormal rail height points, or high / low point defects, are easily generated in the middle of the rail head tread surface, which is very detrimental to the control of rail straightness. These high / low point defects can only be addressed by subsequent grinding, directly affecting production speed and the surface quality of the finished rail. Summary of the Invention

[0005] This invention provides a method for controlling high and low point defects in rail rolling. It adopts a five-pass intermittent rolling method, with the UF mill for the finished product pass and the EF mill for the pre-finished product pass rolling separately. This method can effectively avoid the generation of high and low point defects in rails, improve the straightness of finished rails, and increase production speed.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

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

[0008] 1) The rail rolling production line includes the first billet mill, namely BD1 mill, the second billet mill, namely BD2 mill, and a universal mill. The rail billet is rough rolled by BD1 mill and BD2 mill, and the rail billet is finish rolled by universal mill.

[0009] 2) The universal rolling mill consists of a universal roughing mill (UR mill), a universal edging mill (E mill), and a universal finishing mill (UF mill), arranged sequentially. The rail billet is rolled in a total of 5 passes on the universal rolling mill; specifically:

[0010] The first pass is a continuous rolling mill between UR and E mills, while UF mill runs idle.

[0011] The first two passes are rolled continuously by the E mill and the UR mill, while the UF mill runs idle.

[0012] The UR mill performs the third pass rolling, while the E and UF mills run idle.

[0013] The fourth pass is rolled on the E mill, while the UR and UF mills run idle.

[0014] The 5th pass is rolled on the UF mill, while the UR and E mills run idle.

[0015] After the universal rolling mill completes the rolling process, the finished steel rail is obtained.

[0016] Furthermore, both the BD1 and BD2 mills are two-roll reversible billet mills.

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

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

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

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1) The five-pass intermittent rolling method, with the UF mill for the finished product and the EF mill for the pre-finished product rolling, can effectively avoid the generation of high and low point defects in the rail and improve the straightness of the finished rail.

[0022] 2) The straightness of the finished steel rails meets the standard requirements, eliminating the need for subsequent grinding and improving production speed;

[0023] 3) Particularly suitable for production processes that require high rail straightness (such as high-speed railway rails). Attached Figure Description

[0024] Figure 1This is a schematic diagram of the UF pass pattern when the rail is rolled on the UF rolling mill.

[0025] Figure 2 This is a schematic diagram of the five-pass intermittent rolling process of the universal rolling mill described in this invention.

[0026] In the picture: 1. Rail head Detailed Implementation

[0027] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0028] The present invention discloses a method for controlling high and low point defects in rail rolling, comprising the following processes:

[0029] 1) The rail rolling production line includes the first billet mill, namely BD1 mill, the second billet mill, namely BD2 mill, and a universal mill. The rail billet is rough rolled by BD1 mill and BD2 mill, and the rail billet is finish rolled by universal mill.

[0030] 2) such as Figure 2 As shown, the universal rolling mill consists of a universal roughing mill (UR mill), a edging mill (E mill), and a universal finishing mill (UF mill), arranged sequentially. The rail billet is rolled in a total of 5 passes on the universal rolling mill; specifically:

[0031] The first pass is a continuous rolling mill between UR and E mills, while UF mill runs idle.

[0032] The first two passes are rolled continuously by the E mill and the UR mill, while the UF mill runs idle.

[0033] The UR mill performs the third pass rolling, while the E and UF mills run idle.

[0034] The fourth pass is rolled on the E mill, while the UR and UF mills run idle.

[0035] The 5th pass is rolled on the UF mill, while the UR and E mills run idle.

[0036] After the universal rolling mill completes the rolling process, the finished steel rail is obtained.

[0037] Furthermore, both the BD1 and BD2 mills are two-roll reversible billet mills.

[0038] Furthermore, the E mill is a two-high mill, while the UR mill and UF mill are both four-high mills.

[0039] Furthermore, the rails are high-speed railway rails.

[0040] Furthermore, the difference between the highest and lowest points of the finished rail head tread surface is ≤0.3mm.

[0041] In this invention, when the rail billet is finished by a three-stand universal rolling mill, the usual three-pass reciprocating rolling is improved to the first two stands of the first two passes being rolled continuously, and then each stand of the last three passes is rolled once, for a total of five passes.

[0042] like Figure 2 As shown, specifically, in the first pass, the UR and E mills roll continuously while the UF mill runs idle; in the second pass, the E and UR mills roll continuously while the UF mill runs through; in the third pass, only the UR mill rolls, while both the E and UF mills run idle; in the fourth pass, only the E mill rolls, while both the UR and UF mills run idle; and in the fifth pass, only the UF mill rolls, while both the UR and E mills run idle. Through this five-pass intermittent rolling process, high and low point defects caused by tension build-up and release during the final finishing pass can be avoided.

[0043] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0044]

Example

[0045] In this embodiment, the rail rolling production line includes a first billet mill, namely BD1 mill, a second billet mill, namely BD2 mill, and a universal mill. The rail billet is rough rolled by BD1 mill and BD2 mill, and the rail billet is finish rolled by the universal mill.

[0046] In this embodiment, the universal rolling mill consists of a universal roughing mill (UR mill), a universal edge mill (E mill), and a universal finishing mill (UF mill) arranged sequentially. The rail billet is rolled in a total of 5 passes on the universal rolling mill; specifically:

[0047] The first pass is a continuous rolling mill between UR and E mills, while UF mill runs idle.

[0048] The first two passes are rolled continuously by the E mill and the UR mill, while the UF mill runs idle.

[0049] The UR mill performs the third pass rolling, while the E and UF mills run idle.

[0050] The fourth pass is rolled on the E mill, while the UR and UF mills run idle.

[0051] The 5th pass is rolled on the UF mill, while the UR and E mills run idle.

[0052] After the universal rolling mill completes the rolling process, the finished steel rail is obtained.

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

[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. The difference is that the universal rolling mill performs three passes; specifically:

[0056] The first pass is a continuous rolling mill between UR and E mills, while UF mill runs idle.

[0057] The second pass of the E mill and UR mill is continuous rolling, while the UF mill runs idle.

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

[0059] After the universal rolling mill completes the rolling process, the finished steel rail is obtained.

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

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

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection 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 billet mill, namely BD1 mill, the second billet mill, namely BD2 mill, and a universal mill. The rail billet is rough rolled by BD1 mill and BD2 mill, and the rail billet is finish rolled by universal mill. 2) The universal rolling mill consists of a universal roughing mill (UR mill), a universal edging mill (E mill), and a universal finishing mill (UF mill), arranged sequentially. The rail billet is rolled in a total of 5 passes on the universal rolling mill; specifically: The first pass is a continuous rolling mill between UR and E mills, while UF mill runs idle. The second pass involves continuous rolling between the E and UR mills, while the UF mill runs idle. The UR mill performs the third pass rolling, while the E and UF mills run idle. The fourth pass is rolled on the E mill, while the UR and UF mills run idle. The 5th pass is rolled on the UF mill, while the UR and E mills run idle. After the universal rolling mill completes the rolling process, the finished steel rail is obtained.

2. The method for controlling high and low point defects in rail rolling according to claim 1, characterized in that, Both BD1 and BD2 mills are two-roll reversible billet mills.

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

4. The method for controlling high and low point defects in rail rolling according to claim 1, characterized in that, The rails in question are high-speed railway rails.

5. The method for controlling high and low point defects in rail rolling according to claim 1, characterized in that, The difference between the highest and lowest points of the tread surface of the finished steel rail head is ≤0.3mm.

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