Rail pre-bending method
By constructing a rail pre-bending method based on a third-order Bezier curve and using multiple loading trolleys to pre-bend the rail rolled pieces, the problem of complex bending of the rail rolled pieces after cooling is solved, and a higher yield rate and straightening effect are achieved.
Patent Information
- Application Number
- CN202210980561.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-16
- Publication Date
- 2025-09-09
- Estimated Expiration
- 2042-08-16
AI Technical Summary
During the cooling process, the rail rolled products suffer from inconsistent cooling rates due to cross-section asymmetry, resulting in complex bending, difficulty in entering the straightening machine or poor straightening effect, and low yield rate.
A rail pre-bending method is constructed using a third-order Bezier curve. By obtaining the arc shape parameters of the rail rolled piece during natural cooling, multiple loading trolleys are used under the control system to push the rail rolled piece to pre-bend according to the shape of the third-order Bezier curve, eliminating the dead bend phenomenon and improving the yield rate.
Through the smooth third-order Bezier curve pre-bending, the rail rolled piece can better restore straightness after cooling, eliminating the dead bend problem, improving the yield rate, and ensuring smooth entry into the straightening machine for straightening.
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Figure CN115138728B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of rail production, and in particular to a rail pre-bending method. Background Art
[0002] Due to the asymmetry of the rail section, the area of contact with air during the cooling process is inconsistent, resulting in inconsistent cooling rates. As a result, deformation occurs during cooling and shrinkage, with the larger section bending in the direction of the smaller section. The degree of bending is affected by many factors, including the rail material, model, length of the rolled piece, starting cooling temperature, ambient temperature, rolling speed, and the spacing between the rolled pieces during cooling. The effect is complex. After cooling, the rail rolled piece is often too curved to enter the straightening machine. Even if it enters the straightening machine, the straightening effect is not very good and it is difficult to meet the standards.
[0003] At present, there are two traditional methods to avoid the rail rolled pieces from being unable to pass through the straightening machine due to bending. One is to cut them according to a fixed length and then cool them on a cooling bed. This method solves the straightening problem because the rolled pieces are short and the bending amplitude is small. However, this solution requires sawing off both ends of each section after cooling, resulting in high time cost and a lot of waste. The other is to use pre-bending technology after being put on the cooling bed. The rail rolled pieces are directly pre-bent to an arc according to experience and then cooled. This solution shortens the time cycle and has less waste. However, since the rolled pieces are usually pre-bent according to human experience, it lacks a certain scientific rigor. In addition, it is restricted by various conditions, resulting in the existence of many "W"-shaped and "dead bends" in the rolled pieces before straightening. These parts of the rail rolled pieces cannot be solved by straightening, so the yield rate is low. Summary of the Invention
[0004] In order to improve the yield rate of rail rolled products so that they can be smoothly straightened in a straightening machine later, this paper proposes a rail pre-bending method.
[0005] According to the rail pre-bending method of the present invention, the following steps are included: Step 1: obtaining the shape parameters of the arc formed when the rail rolled piece of the same specification is bent under natural cooling state, and the shape parameters are used to determine the third-order Bezier curve corresponding to the rail rolled piece of this specification; Step 2: pre-bending the rail rolled piece of this specification according to the third-order Bezier curve determined in Step 1.
[0006] Furthermore, the third-order Bezier curve includes two fixed endpoints and two control points, and the shape parameters include the chord height of the arc and the straight-line distance between the two endpoints of the rail rolled piece before bending, wherein the two fixed endpoints correspond to the two endpoints of the rail rolled piece respectively, and the third-order Bezier curve determines the transverse coordinates of the two control points according to the straight-line distance between the two endpoints of the rail rolled piece, and the third-order Bezier curve determines the longitudinal coordinates of the two control points according to the chord height of the arc formed when the rail rolled piece bends due to natural cooling.
[0007] Furthermore, rail rolling products of different specifications correspond to different third-order Bezier curves.
[0008] Furthermore, for the third-order Bezier curve of the same specification of rail rolled products, the horizontal coordinates of the two control points are located at one-third and two-thirds of the straight-line distance between the two fixed endpoints, respectively, and the longitudinal coordinates of the two control points are located at one-half to two-thirds of the chord height of the arc formed when the rail rolled products bend during natural cooling.
[0009] Furthermore, the longitudinal coordinates of the two control points are both located at half the chord height of the arc formed when the rail rolled piece bends due to natural cooling.
[0010] Furthermore, in step 2: a plurality of loading trolleys arranged at intervals along the length direction of the rail rolled piece are used to jointly push and clamp the wide surface of the rail rolled piece on the cooling bed roller. Under the control of the control system, each loading trolley pushes the rail rolled piece to move a preset displacement according to the shape of the third-order Bezier curve to achieve pre-bending of the rail rolled piece.
[0011] Furthermore, in step 2: for the first rail rolled piece in the rail rolled pieces, the control system controls each loading trolley to push the rail rolled piece to move a preset displacement according to the shape of the third-order Bezier curve, and for other subsequent rail rolled pieces, at the same time, reduces the preset displacement of each loading trolley to push the rail rolled piece to move according to the shape of the third-order Bezier curve.
[0012] Furthermore, the preset displacement reduction range of each loading trolley is 5 to 20 mm.
[0013] Furthermore, the reduction range of the preset travel displacement of the loading trolley located in the middle area of the rail rolled piece is greater than the reduction range of the preset travel displacement of the loading trolley located in the two side areas of the rail rolled piece.
[0014] Furthermore, for other subsequent rail rolled pieces, the reduction in the preset displacement of the loading trolley that first enters the side area of the rail rolled piece of the cooling bed roller is smaller than the reduction in the preset displacement of the loading trolley that last enters the side area of the rail rolled piece of the cooling bed roller.
[0015] Compared with the prior art, the rail pre-bending method of the present invention is based on and refers to the shape of the arc formed when the rail rolled piece is naturally cooled, and the shape parameters of the arc are used to construct a corresponding third-order Bezier curve. After the rail is pre-bent according to the shape of the third-order Bezier curve, it can better restore the straightness. At the same time, since the third-order Bezier curve itself is a smoother curve, the deformation of the rail rolled piece during the pre-bending process can be made closer to smooth, which helps to eliminate the problem of "dead bends" generated during the pre-bending process of the rail rolled piece, is beneficial to improving the yield rate, thereby achieving the purpose of enabling it to smoothly enter the straightening machine for straightening later. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is a flow chart of a rail pre-bending method according to an embodiment of the present invention;
[0017] Figure 2 This is a schematic diagram of the arc structure formed when the rail rolled piece bends during natural cooling;
[0018] Figure 3 for the reason Figure 2 Schematic diagram of a third-order Bezier curve determined by the shape parameters of the arc shown;
[0019] Figure 4 This is a top view schematic diagram of the loading trolley pre-bending the rail rolled piece;
[0020] Figure 5 for Figure 4 Schematic side view of . DETAILED DESCRIPTION
[0021] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.
[0022] Figure 1 FIG. 1 shows a flow chart of a rail pre-bending method according to an embodiment of the present invention. Figure 1 As shown, the rail pre-bending method may include the following steps: Step 1 S1: combining Figure 2 As shown, the arc shape (i.e. Figure 2 The shape parameters are used to determine the third-order Bezier curve corresponding to the rail rolled piece 100 of this specification (ie, Figure 3 Step 2 S2: pre-bend the rail rolled piece 100 of this specification according to the third-order Bezier curve determined in step 1 S1.
[0023] Since the rail rolled piece 100 has different cross sections, there are wide side 102 and narrow side 101 (e.g. Figure 5As shown in FIG. 1 , during the natural cooling process of the rail rolled piece 100, the rail rolled piece 100 will bend toward the narrow side 101. The more inconsistent the wide side 102 is with the narrow side 101, the greater the bending deformation. The rail pre-bending method of the embodiment of the present invention pre-bends the rail rolled piece 100, i.e., pre-bends it, so that the rail rolled piece 100 after cooling is kept as straight as possible, thereby achieving the purpose of improving the yield rate, so that it can be smoothly straightened in the straightening machine later. Specifically, the rail pre-bending method of the embodiment of the present invention is based on and refers to the shape of the arc formed when the rail rolled piece 100 is naturally cooled, and the shape parameters of the arc are used to construct a corresponding third-order Bezier curve. After being pre-bent according to the shape of the third-order Bezier curve, the rail can better restore to straightness. At the same time, since the third-order Bezier curve itself is a smoother curve, the deformation of the rail rolled piece 100 during the pre-bending process can be made closer to smoothness, thereby helping to eliminate the problem of "dead bends" generated during the pre-bending process of the rail rolled piece 100, which is beneficial to improving the yield rate.
[0024] Combine Figure 2 and Figure 3 As shown in FIG. 1 , the third-order Bezier curve of a rail rolled piece 100 of the same specification includes two fixed endpoints (i.e., a first fixed point D1 and a second fixed point D2) and two control points (i.e., a first control point P1 and a second control point P2). The shape parameters include the arc chord height H and the straight-line distance between the first endpoint A and the second endpoint B of the rail rolled piece 100 before natural cooling bending (i.e., the initial straight-line length of the rail rolled piece). Figure 3 As shown, the first fixed point D1 and the second fixed point D2 correspond to the first endpoint A and the second endpoint B of the rail rolled piece 100 respectively, and the third-order Bezier curve determines the transverse coordinates of the first control point P1 and the second control point P2 according to the straight-line distance between the first endpoint A and the second endpoint B of the rail rolled piece 100, and the third-order Bezier curve determines the longitudinal coordinates of the first control point P1 and the second control point P2 according to the chord height H of the arc formed when the rail rolled piece 100 is naturally cooled and bent.
[0025] Through this configuration, the positions of the first fixed point D1 and the second fixed point D2, as well as the first control point P1 and the second control point P2, can be determined for a rail rolled piece 100 of the same specification, thereby enabling modeling to form a corresponding third-order Bezier curve based on these positions. It should be noted that the straight-line distance between the first endpoint A and the second endpoint B of the rail rolled piece 100 remains the same before and after pre-bending, and before natural cooling bending occurs.
[0026] According to the present invention, different third-order Bezier curves are corresponding to rail rolled products 100 of different specifications. The transverse coordinates of the first fixed point D1 and the second fixed point D2 are determined by the linear distance between the two endpoints of the rail rolled product 100 of the corresponding specification. Furthermore, the longitudinal coordinates of the first control point P1 and the second control point P2 are determined by the chord height H of the arc formed when the rail rolled product 100 of the corresponding specification is naturally cooled and bent. This configuration allows the positions of the first fixed point D1 and the second fixed point D2, as well as the first control point P1 and the second control point P2, to be determined for rail rolled products 100 of different specifications, thereby enabling the corresponding third-order Bezier curve to be modeled based on these positions.
[0027] According to the present invention, for the third-order Bezier curve of the rail rolled piece 100 of the same specification, the transverse coordinates of the first control point P1 and the second control point P2 are respectively located at one-third and two-thirds of the straight-line distance between the first fixed point D1 and the second fixed point D2, and the longitudinal coordinates of the first control point P1 and the second control point P2 are both located at one-half to two-thirds of the chord height H of the arc formed when the rail rolled piece 100 is naturally cooled and bent. By setting the transverse coordinates of the first control point P1 and the second control point P2 at one-third and two-thirds of the straight-line distance between the first fixed point D1 and the second fixed point D2, respectively, the rail rolled piece 100 can be evenly divided into three sections, so that the left and right sides of the rail rolled piece 100 after pre-bending are basically symmetrical curves. On this basis, the longitudinal coordinates of the first control point P1 and the second control point P2 are both set at one-half to two-thirds of the chord height H of the arc formed when the rail rolled piece 100 is naturally cooled and bent, so that the arc of the basically symmetrical curves on both sides is larger, and the arc of the curve in the middle is smaller. The shape of the third-order Bezier curve formed in this way is closer to the shape formed by the rail rolled piece 100 after natural cooling and bending. Therefore, the rail rolled piece 100 pre-bent according to the shape of the third-order Bezier curve can better restore to straightness. In addition, the introduction of the third-order Bezier curve also makes the curve at the connection of the three sections smoother, which helps to eliminate the problem of "dead bends" generated during the pre-bending process of the rail rolled piece 100, which is conducive to improving the yield rate.
[0028] Preferably, in order to better restore the straightness of the rail rolled piece 100, the longitudinal coordinates of the first control point P1 and the second control point P2 can be set at half the chord height H of the arc formed when the rail rolled piece 100 bends during natural cooling.
[0029] According to the present invention, combined Figure 4 and Figure 5As shown, in step 2 S2, a plurality of loading trolleys 10 spaced apart along the length of the rail rolled piece 100 can be used to jointly push and clamp the wide surface 102 of the rail rolled piece 100 on the cooling bed roller 201 of the cooling bed 200. Under the control of the control system, each loading trolley 10 pushes the rail rolled piece 100 to move a preset displacement according to the shape of a third-order Bezier curve to achieve pre-bending of the rail rolled piece 100. This arrangement enables the rail rolled piece 100 to be accurately pre-bent into the shape of a preset third-order Bezier curve by controlling the plurality of loading trolleys 10 to move respectively at the preset displacement.
[0030] Specifically, if Figure 5 As shown, during the production process, the rail rolled piece 100 falls on the cooling bed roller 201 of the cooling bed 200 for loading after hot rolling. The loading trolley 10 first moves forward and uses its "boot head" to push the rail rolled piece 100 forward to the same level to the cooling bed platform 202, and then the loading trolley 10 rises to lift the rail rolled piece 100. In this way, the wide surface 102 of the rail rolled piece 100 will be stuck in the groove 11 of the boot head, thereby fixing the rail rolled piece 100. In the next step, each loading trolley 10 moves forward a different distance to make the rail rolled piece 100 form the required curve curvature, and then the loading trolley 10 descends and places the rail rolled piece 100 on the cooling bed platform 202 to wait for cooling.
[0031] In a preferred embodiment, in step two S2: when implementing the pre-bending process, for the first rail rolled piece 100 in the rail rolled pieces 100, the control system controls each loading trolley 10 to push the rail rolled piece 100 to move a preset displacement according to the shape of the third-order Bezier curve, while for the subsequent other rail rolled pieces 100, the preset displacement of each loading trolley 10 to push the rail rolled piece 100 according to the shape of the third-order Bezier curve can be reduced at the same time. In this embodiment, the influence of the ambient temperature on the first rail rolled piece 100 when entering the cooling bed 200 is taken as a reference. At this time, the influence of the ambient temperature on the first rail rolled piece 100 is greater than that on the subsequent other rail rolled pieces 100 when entering the cooling bed 200. Therefore, the curvature of the first rail rolled piece 100 during natural cooling is larger than that on the subsequent other rail rolled pieces 100 during natural cooling. After the first rail rolled piece 100 is pre-bent in the opposite direction according to the shape of a third-order Bezier curve, the curvature of the curvature of the subsequent other rail rolled pieces 100 during natural cooling is relatively small. Therefore, when the reverse pre-bending is performed according to the shape of a third-order Bezier curve, the degree of bending of the subsequent other rail rolled pieces 100 can be reduced according to actual conditions by reducing the forward displacement of each loading trolley 10 to compensate for the influence of the ambient temperature, so that the rail rolled piece 100 can be better restored to straightness after pre-bending and cooling.
[0032] Preferably, according to different actual conditions, such as different rail models, the reduction range of the preset displacement of each loading trolley can be set to 5 to 20 mm.
[0033] In a more preferred embodiment, for other subsequent rail rolled pieces 100, the reduction range of the preset travel displacement of the loading trolley 10 located in the middle area of the rail rolled piece 100 may be greater than the reduction range of the preset travel displacement of the loading trolley 10 located in the two side areas of the rail rolled piece 100. Through this arrangement, the reduction range of the preset travel displacement of the loading trolley 10 located in the middle area of the rail rolled piece 100 is larger, while the reduction range of the preset travel displacement of the loading trolley 10 located in the two side areas of the rail rolled piece 100 is relatively smaller, so that the force on the two side areas of the rail rolled piece 100 is reduced relative to that on the middle area, thereby facilitating further reducing the degree of bending of the rail rolled piece 100 as a whole, compensating for the influence of the ambient temperature, and thus enabling the rail rolled piece 100 to better recover its straightness after pre-bending and cooling.
[0034] Furthermore, for other subsequent rail rolled products 100, the reduction amplitude of the preset travel displacement of the loading trolley 10 that first enters the side area of the rail rolled product 100 of the cooling bed roller 201 of the cooling bed 200 is smaller than the reduction amplitude of the preset travel displacement of the loading trolley 10 that last enters the side area of the rail rolled product 100 of the cooling bed roller 201. Since the head of the rail rolled piece 100 (i.e., the side area of the rail rolled piece 100 that first enters the cooling bed roller 201 of the cooling bed 200) is out of the rolled piece earlier, the head is exposed to air cooling earlier, resulting in that the temperatures of various areas of the entire rail rolled piece 100 are actually not consistent. Therefore, the above-mentioned further adjustment is added on the basis of the third-order Bezier curve. The adjustment comprehensively considers the ambient temperature, rolling speed, cooling bed running speed and distance, and different rail rolled piece models, and fine-tunes the strokes of multiple loading trolleys 10. By setting the reduction amplitude of the preset displacement of the loading trolley 10 of the side area (i.e., the head) of the rail rolled piece 100 that first enters the cooling bed roller 201 to be smaller than that of the other side area, the head area can obtain a larger bending arc than the tail area to compensate for the larger bending of the head area caused by the external environment.
[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.
Claims
1. A rail pre-bending method, characterized in that: The following steps are involved: Step 1: obtaining shape parameters of an arc formed when a rail rolled piece of the same specification is bent under natural cooling, wherein the shape parameters are used to determine a third-order Bezier curve corresponding to the rail rolled piece of the same specification; Step 2: pre-bending the rail rolled piece of the specification according to the third-order Bezier curve determined in step 1; The third-order Bezier curve includes two fixed endpoints and two control points, and the shape parameters include the chord height of the arc and the straight-line distance between the two endpoints of the rail rolled piece before bending. The two fixed endpoints correspond to the two endpoints of the rail rolled piece, respectively. The third-order Bezier curve determines the transverse coordinates of the two control points based on the straight-line distance between the two endpoints of the rail rolled piece, and the third-order Bezier curve determines the longitudinal coordinates of the two control points based on the chord height of the arc formed when the rail rolled piece bends due to natural cooling. For the third-order Bezier curve of the rail rolled product of the same specification, the transverse coordinates of the two control points are respectively located at one-third and two-thirds of the straight-line distance between the two fixed end points, and the longitudinal coordinates of the two control points are both located at one-half to two-thirds of the chord height of the arc formed when the rail rolled product is bent during natural cooling; In step 2, for the first rail rolled piece, the control system controls each of the loading trolleys to push the rail rolled piece by a preset displacement according to the shape of the third-order Bezier curve, and for subsequent rail rolled pieces, the control system controls each of the loading trolleys to push the rail rolled piece by a preset displacement according to the shape of the third-order Bezier curve. The reduction range of the preset travel displacement of the loading trolley located in the middle area of the rail rolled piece is greater than the reduction range of the preset travel displacement of the loading trolley located in the two side areas of the rail rolled piece; For the other subsequent rail rolled pieces, the reduction amplitude of the preset travel displacement of the loading trolley that first enters the side area of the rail rolled piece of the cooling bed roller is smaller than the reduction amplitude of the preset travel displacement of the loading trolley that last enters the side area of the rail rolled piece of the cooling bed roller.
2. The rail pre-bending method according to claim 1, characterized in that: The rail rolled products of different specifications correspond to different third-order Bezier curves.
3. The rail pre-bending method according to claim 1, characterized in that: The longitudinal coordinates of the two control points are both located at half the chord height of the arc formed when the rail rolled piece is bent due to natural cooling.
4. The rail pre-bending method according to any one of claims 1 to 3, characterized in that: In the step 2: a plurality of loading trolleys arranged at intervals along the length direction of the rail rolled piece are used to jointly push and clamp the wide surface of the rail rolled piece on the cooling bed roller. Under the control of the control system, each loading trolley pushes the rail rolled piece to move a preset displacement according to the shape of the third-order Bezier curve to achieve pre-bending of the rail rolled piece.
5. The rail pre-bending method according to claim 1, characterized in that: The reduction range of the preset displacement of each loading trolley is 5 to 20 mm.
Citation Information
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