Processing method and heel-end die of 50AT1-43kg / m rail

Abstract

The invention discloses a processing method of a 50AT1‑43kg / m rail and a heel-end mold thereof, and belongs to the technical field of turnout processing. It includes a pre-forging mold and a final forging mold, the pre-forging mold is a 50AT1‑50kg / m pre-forging mold, and the final forging mold is modified from a 50AT1‑50kg / m final forging mold, and the modification process is as follows: the forming section waist mold of the 50AT1‑50kg / m final forging mold is adjusted as follows: the lower jaw of the rail head is cut by 5.86mm, the slope is processed to 1:3, and the intersection of the rail waist and the rail head arc is processed into R5 / R10; the rail bottom is cut uphill by 0.77‑1.94mm, the slope of the upper slope is processed to 1:3, the slope of the lower slope is processed to 1:6, and the intersection of the rail waist and the rail bottom arc is processed to R15. After forging is completed, the rail head and the rail bottom are processed by milling, and the processing amount of the top surface of the rail head is 8mm, and the processing amount of the bottom surface of the rail bottom is 4mm.

Description

Technical Field

[0001] The invention belongs to the technical field of turnout processing methods, and in particular relates to a processing method for a 50AT1-43kg / m rail and a heel-end mold thereof. Background Art

[0002] With the expansion of the company's business and scope, the company's order types have become more and more in recent years, and the products of special rails involved have also become richer. In addition to the company's existing 60AT1-60kg / m special-shaped rails, 50AT1-50kg / m special-shaped rails, 60 -50kg / m special-shaped rails and 50 -43kg / m special-shaped rails, some factory and mine special transportation lines have a demand for 50AT1-43kg / m special-shaped rails. However, the company currently does not have production molds for such products. Therefore, the company decided to develop a set of 50AT1-43kg / m special-shaped rail molds.

[0003] At present, most of the point rails of station lines and in-plant transportation lines are made of 50AT1 special section rails, but some low-speed turnouts are still made of 43kg / m standard section rails. The types of station turnouts are complicated, and the front and rear laying of various turnouts need to be connected in a specific form. This mold development is to achieve the connection transition of these two different types of turnouts. Two different rail types require special products to achieve. The raw material part of the 50AT1-43kg / m point rail is made of 50AT1 special section rails, and the die forging heel end needs to be forged into a 43kg / m rail section. This point rail is a small batch customized product. The company hopes to develop a set of modified molds at a relatively low cost. Therefore, we plan to use the original mold for modification, and process the 43kg / m rail cavity and the mold for the transition part with the 50AT1 rail to meet the forging of special rail types. Summary of the invention

[0004] The embodiment of the present invention provides a processing method for 50AT1-43kg / m rail and a heel-end mold thereof, which can produce 50AT1-43kg / m rail by simply adjusting the 50AT1-50kg / m special-shaped rail mold with greater wear, thereby enriching the company's product line and reducing production costs. The technical solution is as follows:

[0005] On the one hand, an embodiment of the present invention provides a 50AT1-43kg / m rail heel end die, including a pre-forging die and a final forging die, wherein the pre-forging die is a 50AT1-50kg / m pre-forging die, and the final forging die is modified from a 50AT1-50kg / m final forging die, and the modification process is as follows: the forming section waist die of the 50AT1-50kg / m final forging die is adjusted as follows: the rail waist is aligned; the lower jaw of the rail head is cut by 5.86mm, the slope is processed to 1:3, and the intersection of the rail waist and the rail head arc is processed to R5 / R10; the rail bottom is cut uphill by 0.77-1.94mm, the slope of the upper slope is processed to 1:3, the slope of the lower slope is processed to 1:6, and the intersection of the rail waist and the rail bottom arc is processed to R15.

[0006] On the other hand, an embodiment of the present invention further provides a method for processing a 50AT1-43kg / m rail, the method comprising: performing pre-forging using a 50AT1-50kg / m pre-forging die as a pre-forging die, and performing final forging using the aforementioned final forging die; after forging, milling is used to process the rail head and rail bottom, the top surface of the rail head having a vertical processing amount of 8mm, the bottom surface of the rail bottom having a vertical processing amount of 4mm and being processed to a width of 114mm.

[0007] Specifically, the forging process includes the following steps:

[0008] S101: Draw a line 790 mm from the forged heel of the rail.

[0009] S102: Send the rail end with a length of 790 mm into an electric heating furnace and heat it to 1060±30℃.

[0010] S103: The rail is taken out from the electric heating furnace, turned 180 degrees and sent to the forging station of the press machine to completely put the rail head into the mold.

[0011] S104: At the pre-forging station, pull out the rail bottom plate, apply pressure, use the waist die of the pre-forging die to squeeze the rail waist, and close the upper and lower die seats.

[0012] S105: Operate the die changing device, change the final forging die to the forging station, cover the large rail bottom plate and roll it to flatten the bottom surface of the formed rail section. Pull out the large rail bottom plate and squeeze the rail waist; push in the small pressing plate and roll the rail bottom three to four times, then push in the large rail bottom plate and roll it.

[0013] S106: Take the rail out of the forging station of the press, flip it 180 degrees and send it to the electric heating furnace.

[0014] S107: Transfer the rail to the heating station to reheat the formed part to 1060±30℃; take the rail out of the electric heating furnace, turn it 180° and send it to the press forging station.

[0015] S107: At the final forging station, there is no large rail bottom plate to squeeze the rail waist; the small pressing plate presses the rail bottom three to four times; the large rail bottom plate is molded and finally formed.

[0016] S108: Take the rail out of the press forging station.

[0017] Furthermore, after forging is completed, the rail is subjected to a blast heat treatment.

[0018] Specifically, the air blowing heat treatment includes the following steps:

[0019] S201: Adjust the height of the heating furnace to the rail height of 50-43kg / m, and adjust the heating temperature probe and the blowing temperature probe to the temperature measuring position.

[0020] S202: Adjust the height of the air box nozzle to 15-17 mm from the top of the rail and 17-20 mm from the side of the rail.

[0021] S203: Before entering the furnace, a furnace heating position mark and a blow cooling position mark are marked on the top of the rail; the furnace heating position mark and the blow cooling position mark are respectively located at 240 mm and 1760 mm in the direction of the raw material, 790 mm away from the forging mark.

[0022] S204: The rails are sent into a heating furnace according to the markings for heating, and are heated to 920±20°C before being taken out of the furnace.

[0023] S205: The heated part of the rail is withdrawn into the air box to ensure that the heated area of ​​the forging heel end is completely blown in the air box for heat treatment, and the raw material end of the rail shall not be warped. The air cooling parameters are set as follows: air pressure 0.18±0.02MPa, cooling end temperature 400±20℃.

[0024] S206: After the rails are cooled to room temperature, the rails are moved into a sandblasting room for sandblasting to remove surface oxide scale.

[0025] S207: After the rails are sandblasted, magnetic particle inspection is performed on the forged parts.

[0026] Specifically, the rail is milled after the air-blowing heat treatment, and the steps include:

[0027] S301: Send the rail to the top adjustment machine for top surface straightening to ensure horizontal transition of the cross section.

[0028] S302: Saw the forged front rail to remove irregular parts of the end to ensure that the length of the formed section is 450±30mm.

[0029] S303: Milling the rail bottom, milling off 4mm of the rail bottom in the forming section; after cutting the rail bottom, mill one cut on each side of the rail bottom until the rail bottom width is 114mm, and remove the burrs of the rail bottom.

[0030] S304: After the rail bottom is milled, the rail bottom is adjusted to a table height of 20 mm through a top adjustment process.

[0031] S305: The excess part of the rail top surface is processed by a CNC milling machine, and the standard rail top surface profile is milled out by a forming tool; at the rail top, the entire raw material and the transition section and forming section are milled 8mm.

[0032] The embodiment of the present invention provides a processing method for a 50AT1-43kg / m rail and a heel-end mold thereof, which can produce a 50AT1-43kg / m rail by simply adjusting a 50AT1-50kg / m special-shaped rail mold with greater wear, thereby enriching the company's product line and reducing production costs. In addition, after testing, the accuracy and hardness of the obtained product meet the use requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the standard cross-section of a 50kg / m rail;

[0034] Figure 2 This is the standard cross-section of a 43kg / m rail;

[0035] Figure 3 It is the adjustment diagram of 50AT1-43kg / m rail relative to 50AT1-50kg / m rail;

[0036] Figure 4 It is the dimensional change diagram of 50AT1-43kg / m rail relative to 50AT1-50kg / m rail;

[0037] Figure 5 It is a schematic diagram of the structure of the final forging die;

[0038] Figure 6 It is a processing schematic diagram of the waist mold of the forming section. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] The embodiment of the present invention provides a method for processing a 50AT1-43kg / m rail and a heel-end mold thereof. The development of the mold and the processing process of the rail are as follows:

[0041] 1. Mould development

[0042] 1.1 Mold design

[0043] Through comparative analysis of the data of the two rail sections, based on the characteristics of die forging and forming, it is necessary to first determine the die size of the forming section to ensure that the cross-sectional dimensions of the rail meet the requirements of the railway technical standard TB / T 2344.1-2020 "Rail Part 1: 43kg / m-75kg / m Rail". Then the position processing requirements of the die transition section are specified, and the profile needs to be smoothly transitioned. Considering that the 50kg / m rail is closest to the 43kg / m rail in profile and size, and the company has multiple sets of 50AT1-50kg / m special-shaped rail dies with greater wear, we decided to use the 50AT1-50kg / m special-shaped rail dies for modification. By comparison, we found that the cross-sectional profile of the 50kg / m rail is larger than that of the 43kg / m rail, and there is room for modification.

[0044] According to the actual situation in the factory, we decided to use the 50AT1-50kg / m mold for modification. The 50AT1-43kg / m pointed rail to be produced this time requires the top surface of the rail to drop 8mm in length, and the bottom of the rail raw material part and the forming section are 20mm high, which is 4mm more than the 24mm high of the 50AT1-50kg / m die forging heel. First, the two special-shaped rails are positioned relative to the 50AT1 rail (the position of the 50AT1 rail raw material remains unchanged) to determine the relative position of the 50kg / m rail and the 43kg / m rail after forging before and after the mold modification, so as to determine the mold modification plan.

[0045] By comparing the difference between the 50kg / m and 43kg / m forming sections, it can be seen that the waist mold of the 50AT1-50kg / m special-shaped rail mold is modified and processed. The waist mold is cut off a part of the 43kg / m rail head jaw slope rail, and the rail bottom upslope is the same (cutting 0.77-1.94mm, the specific cutting amount is shown in the figure, to ensure that the rail bottom upslope is the same as the 43kg / m rail bottom upslope), and at the same time, the fishtail space arc of the 43kg / m rail is processed to make the newly obtained contour consistent with the fishtail space of the 43kg / m rail to meet the waist mold size of the 50AT1-43kg / m special-shaped rail. The head width of 43kg / m rails and 50kg / m rails is the same. We do not process the mold of the head section separately. The forming section of 43kg / m rails is 8mm lower than that of 50kg / m rails, which reserves the processing volume for the rail top processing required by the subsequent drawings. The overall arc and slope are machined with a forming milling cutter after forging. The waist thickness of the rail can be adjusted within a small range by adjusting the thickness of the adjustment piece between the panel and the mold, and the waist thickness of the 50kg / m rail is 1mm thicker than that of the 43kg / m rail, which is within the control range (within the specified error range, no processing can be done or a slight processing can be done later by milling). The bottom width of this special-shaped rail is 132mm, which is quite different from the required 114mm, and can be milled after forging. In terms of rail height, the 50kg / m rail is 12mm larger than the 43kg / m rail. In the rail bottom part, since the bottom height of the 50AT1-43 special-shaped rail is 20mm, and the bottom height of the 50AT1-50 rail is 24mm, the difference between the two rail bottom heights is 4mm, which is removed by milling on the lower surface of the rail with a milling cutter.

[0046] See also Figure 6 , the original mold was modified and processed, the light-colored part was cut off, and the retained dark-colored part could meet the needs of the waist mold for the forming section of the 50AT1-43kg / m special-shaped rail. The outline of the forging mold was preliminarily drawn using 2D and 3D software, and then the mold model and the rail raw material model were used to simulate the forging process, and the 50AT1 special-section rail was substituted into it, and the forging machine was simulated to perform heel-end forging processing.

[0047] After the simulation, the profile of the forming section (43kg / m) meets the design requirements (milling is required before final forming after forging), and the transition section can also meet the requirements of smooth transition.

[0048] 1.2 Mould Manufacturing

[0049] After the initial draft of the mold modification is completed, the mold is processed with high precision by the CNC machining center according to the drawings, and its size is processed and the angle is adjusted by the cylindrical grinder. There are two sets of molds this time, one is the pre-forging mold and the other is the final forging mold. The functions of the pre-forging mold are: 1. Ensure that the metal flows without defects and is easy to fill the groove; 2. Reduce the loss of material flowing to the burr groove; 3. Reduce the wear of the final forging die (due to the reduction of the flow of metal); 4. Obtain the desired streamline and facilitate the control of the mechanical properties of the forging. Pre-forging is mainly to prevent excessive deformation of the forging once, which has a huge impact on the wear of the mold. Therefore, we do not change the pre-forging mold and directly apply the pre-forging mold of the 50AT1-50 special-shaped rail. The final forging mold is to characterize the rail. After the rail is punched by the pre-forging mold, it is characterized into the desired rail shape after final forging, and the short rolling plate is used to punch the rail profile so that the rail profile can fit accurately. This modification mainly involves the final forging mold.

[0050] After the mold was manufactured, we used a test sample to test the mold. The modified waist mold basically met the design requirements and could proceed to the next step of trial operation.

[0051] 2. Forging test run of modified die

[0052] In order to avoid the influence of raw materials, we selected relatively standard raw materials for testing. The mold used is preheated before forging, which reduces the temperature difference and makes the rail cool faster, resulting in deviation of the rail profile during forging, so that the surface temperature of the mold cavity is evenly distributed at about 500℃. Then the forging operation is carried out. The forging process includes the following steps:

[0053] S101: Draw a line 790 mm from the forged heel of the rail, specifically at the rail head.

[0054] S102: Operate the robot to send the 790mm long rail end into the electric heating furnace and heat it to 1060±30℃.

[0055] S103: Operate the manipulator to take the rail out of the electric heating furnace, flip it 180 degrees, and send it to the forging station of the press to completely put the rail head into the mold.

[0056] S104: At the pre-forging station, pull out the rail bottom plate, apply pressure, use the waist die of the pre-forging die to squeeze the rail waist, and close the upper and lower die seats.

[0057] S105: Operate the die changing device, change the final forging die to the forging station, cover the large rail bottom plate and roll it to flatten the bottom surface of the formed rail section. Pull out the large rail bottom plate and squeeze the rail waist; push in the small pressing plate and roll the rail bottom three to four times, then push in the large rail bottom plate and roll it.

[0058] S106: Operate the manipulator to take the rail out of the forging station of the press, flip it 180 degrees, and then send it to the electric heating furnace.

[0059] S107: Transfer the rail to the heating station to reheat the formed part to 1060±30℃; operate the manipulator to take the rail out of the electric heating furnace, turn it 180° and send it to the press forging station.

[0060] S107: At the final forging station, there is no large rail bottom plate to squeeze the rail waist; the small pressing plate presses the rail bottom three to four times; the large rail bottom plate is molded and finally formed.

[0061] S108: Operate the robot to take the rail out of the forging station of the press.

[0062] During forging, the head die is 50AT1-50; the large and small rail bottom plates are made of 50AT1-50 dies; pay attention to the condition that the fishtail space is uniform (front and rear deviation is less than 0.5mm), the lower jaws of 43 rail and 50AT1 rail are adjusted into a straight line, and also pay attention to whether the gap difference of the upslope of the rail bottom of the two rail types is uniform (within 0.5mm).

[0063] After adjusting the parameters several times, we obtained a relatively ideal finished product. After forging, there were no defects such as folds, pits, transverse scratches, scars and indentations on the forged part of the rail. After magnetic particle inspection and ultrasonic inspection, no cracks were found in the forming section and transition section. The rail head height, rail waist thickness, and rail bottom offset relative to the vertical axis in the transition section transitioned evenly, and each intersecting surface was smooth and round. All dimensions met the standard requirements after measurement or sample inspection. The data of the forming section of the rail was measured, and the data obtained are shown in Table 1:

[0064] Table 1

[0065]

[0066] It can be seen from Table 1 that the rail head width, rail bottom width, rail waist thickness, forming section length, cross-sectional symmetry, transition section rail head width and fishtail space of the forged product all meet the requirements.

[0067] 3. Blowing heat treatment after forging

[0068] The rails after forging are subjected to air-blowing heat treatment, which can ensure that the hardness of the special-shaped rails can meet the standard requirements. Previously, we considered that if the top surface of the rail was milled 8mm, the depth of the quenching layer of the rail might be insufficient, and the top surface hardness would not meet the standard requirements. After air-blowing heat treatment, even if the top of the rail is milled off 8mm, the hardness of the product can meet the standard requirements. Therefore, machining is arranged after the rails are air-blowing heat treatment. Air-blowing heat treatment includes the following steps:

[0069] S201: Adjust the height of the heating furnace to the rail height of 50-43kg / m, and adjust the heating temperature probe and the blowing temperature probe to the temperature measuring position.

[0070] S202: Adjust the height of the air box nozzle to 15-17 mm from the top of the rail and 17-20 mm from the side of the rail.

[0071] S203: Before entering the furnace, mark the furnace heating position and the air cooling position on the top of the rail. The furnace heating position and the air cooling position are respectively 240mm and 1760mm away from the forging line at 790mm in the direction of the raw material.

[0072] S204: The rails are sent into a heating furnace according to the markings for heating, and are heated to 920±20°C before being taken out of the furnace.

[0073] S205: The heated part of the rail is withdrawn into the air box to ensure that the heated area of ​​the forging heel end is completely blown in the air box for heat treatment, and the raw material end of the rail shall not be warped. The air cooling parameters are set as follows: air pressure 0.18MPa, cooling end temperature 400±20℃.

[0074] S206: After the rails are cooled to room temperature, the rails are moved into a sandblasting room for sandblasting to remove surface oxide scale.

[0075] S207: After the rails are sandblasted, magnetic particle inspection is performed on the forged parts.

[0076] Type test of rails after air-blast heat treatment

[0077] In order to confirm the air-blowing heat treatment status of the rail, it is necessary to conduct a type test on the rail. Sampling is carried out according to the provisions of TB / T 2344.3-2018 "Rail Part 3: Special-shaped Rail". The raw material of the rail we forged this time is U75V. The results are as follows:

[0078] (1) The hardness of the rail top surface was tested and the result was between 340-420 HBW.

[0079] (2) The hardness of the rail head section was tested and the result was between 36-41HRC.

[0080] (3) A tensile test was carried out, and the average values ​​of the test results were as follows: the tensile strength Rm of the specimen was 1120 MPa, and the elongation after fracture A was 10.6%.

[0081] (4) The surface decarburization layer was tested. The decarburization layer in the forming section was 0.223 mm, and the depth of the decarburization layer in the transition section was 0.262 mm.

[0082] (5) Metallographic microstructure test was carried out, and the metallographic structure was fine pearlite structure + a small amount of ferrite structure, without martensite, bainite and grain boundary cementite.

[0083] After a series of tests and inspections, the performance indicators of the 50AT1-43 special-shaped rail can meet the standard requirements.

[0084] 4. Machining after forging

[0085] After the heat treatment, the workpiece is machined, which includes the following steps:

[0086] S301: Send the rail to the top adjustment machine for top surface straightening to ensure horizontal transition of the cross section.

[0087] S302: Saw the forged front rail to remove irregular parts of the end to ensure that the length of the formed section is 450±30mm.

[0088] S303: Milling the rail bottom, milling off 4mm of the rail bottom in the forming section; after cutting the rail bottom, mill one cut on each side of the rail bottom until the rail bottom width is 114mm, and remove the burrs of the rail bottom.

[0089] S304: After the rail bottom is milled, the rail bottom is adjusted to a table height of 20 mm through a top adjustment process.

[0090] S305: The excess part of the rail top surface is processed by a CNC milling machine, and the standard rail top surface profile is milled out by a forming tool; at the rail top, the entire raw material and the transition section and forming section are milled 8mm.

[0091] S306: Inspection was carried out in accordance with the requirements of the drawings and TB / T2344.1-2020 Rail Part 1: 43kg / m-75kg / m Rails. The cross-sectional dimensions of the processed rails met the requirements, and the connection surfaces had smooth transitions and met the requirements.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. 50AT1-43kg / m rail processing method, characterized in that: 50AT1-43kg / m point rails are processed using 50AT1 special section rails as raw materials; pre-forging is performed using a 50AT1-50kg / m pre-forging die as a pre-forging die, and final forging is performed using a final forging die; after forging, the rails are subjected to a blow heat treatment, and then the rail head and rail bottom are processed by milling, the top surface of the rail head is processed by 8mm in the vertical direction, the bottom surface of the rail bottom is processed by 4mm in the vertical direction and is processed to a width of 114mm; The final forging die is modified from the final forging die of 50AT1-50kg / m, and the modification process is as follows: the waist die of the forming section of the final forging die of 50AT1-50kg / m is adjusted as follows: the rail waist is aligned; the lower jaw of the rail head is cut by 5.86mm, the slope is processed to 1:3, and the intersection of the rail waist and the rail head arc is processed to R5 / R10; the rail bottom is cut upslope by 0.77-1.94mm, the slope of the upper slope is processed to 1:3, the slope of the lower slope is processed to 1:6, and the intersection of the rail waist and the rail bottom arc is processed to R15; Blow heat treatment includes the following steps: S201: Adjust the height of the heating furnace to the rail height of 50-43kg / m, and adjust the heating temperature probe and the blowing temperature probe to the temperature measurement position; S202: Adjust the height of the air box nozzle to 15-17 mm from the top of the rail and 17-20 mm from the side of the rail; S203: Before entering the furnace, a furnace heating position mark and a blow cooling position mark are marked on the top of the rail; the furnace heating position mark and the blow cooling position mark are respectively 240 mm and 1760 mm away from the forging line at a position of 790 mm in the direction of the raw material; S204: Send the rails into the heating furnace according to the markings for heating, and heat to 920±20℃ before being taken out of the furnace; S205: The heated part of the rail is withdrawn into the air box to ensure that the heated area of ​​the forging heel end is completely blown in the air box for heat treatment, and the rail raw material end shall not be warped. The air cooling parameters are set as follows: air pressure 0.18±0.02MPa, cooling end temperature 400±20℃; S206: After the rails are cooled to room temperature, the rails are moved into a sandblasting room for sandblasting to remove surface oxide scale; S207: After the rails are sandblasted, magnetic particle inspection is performed on the forged parts.

2. The processing method according to claim 1, characterized in that: The forging process includes the following steps: S101: Draw a line 790 mm from the forged heel of the rail; S102: Send the rail end 790mm long into the electric heating furnace and heat it to 1060±30℃; S103: Take the rail out of the electric heating furnace, turn it 180 degrees and send it to the forging station of the press machine to completely put the rail head into the mold; S104: At the pre-forging station, the rail bottom plate is pulled out, pressure is applied, the rail waist is squeezed with the waist die of the pre-forging die, and the upper and lower die seats are closed; S105: Operate the die changing device, change the final forging die to the forging station, cover the large rail bottom plate and roll it to flatten the bottom surface of the formed rail section; pull out the large rail bottom plate and squeeze the rail waist; push in the small pressing plate and roll the rail bottom three to four times, and then push in the large rail bottom plate and roll it; S106: Take the rail out of the forging station of the press, turn it 180 degrees and send it to the electric heating furnace; S107: Transfer the rail to the heating station to reheat the formed part to 1060±30℃; take the rail out of the electric heating furnace, turn it 180° and send it to the press forging station; S107: At the final forging station, the rail waist is squeezed without a large rail bottom plate; the small pressing plate presses the rail bottom three to four times; the large rail bottom plate is molded and finally formed; S108: Take the rail out of the press forging station.

3. The processing method according to claim 1, characterized in that: The rails are milled after the air-blowing heat treatment, which includes the following steps: S301: Send the rail to the top adjustment machine for top surface straightening to ensure horizontal transition of the cross section; S302: Saw the forged front rail to remove irregular parts of the end to ensure that the length of the forming section is 450±30mm; S303: Milling the rail bottom, milling off 4mm of the rail bottom in the forming section; after cutting the rail bottom, mill one cut on each side of the rail bottom until the rail bottom width is 114mm, and remove the burrs of the rail bottom; S304: After the rail bottom is milled, the rail bottom is adjusted to a table height of 20 mm through a top adjustment process; S305: The excess part of the rail top surface is processed by a CNC milling machine, and the standard rail top surface profile is milled out by a forming tool; at the rail top, the entire raw material and the transition section and forming section are milled 8mm.

Images