Oil rail preform design method and die designed using the same

Abstract

The present application relates to the technical field of stainless steel oil rail pre-forging design, and discloses an oil rail pre-forging design method and a die designed by the method, comprising the following steps: S1, pre-forging design; S2, pre-forging weight analysis: whether the pre-forging weight is greater than the finish-forging weight is analyzed, if the analysis is "no", the pre-forging is optimized and the pre-forging design in S1 is performed again; S3, pre-forging die design; S4, numerical simulation; S5, simulation result analysis: whether there is a defect, if there is a defect, the pre-forging is optimized and the pre-forging design in S1 is performed again; S6, when there is no defect, the design is completed. By using the method, the oil rail pre-forging can be quickly designed, and by combining with numerical simulation, the phenomena such as forging edge collapse, skin clamping, flow line disorder and finish-forging die cracking can be effectively avoided. The die designed by using the oil rail pre-forging design method can reduce the product test frequency, shorten the product development cycle, and thus the product development cost can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stainless steel oil rail preform design, in particular to an oil rail preform design method and a die designed by using the method. BACKGROUND

[0002] At present, most high-pressure oil rail forgings are formed by multi-step hot die forging.

[0003] Patent No. CN111590004B discloses a manufacturing process for manufacturing an integral stainless steel oil rail forging, which includes five steps: S1 blanking, S2 heating, S3 hot forging, S4 trimming, and S5 post-forging treatment. The trimming uses a trimming and correcting composite die, and appropriate compensation is added to the trimming die to ensure the straightness and position of the forging.

[0004] Patent No. CN107299295B discloses a forming process for ultra-high pressure stainless steel forged oil rail, which mainly includes eight steps: 1) blanking; 2) medium frequency heating; 3) pre-forging; 4) finish forging; 5) trimming; 6) quenching; 7) shot blasting; and 8) pickling and passivation. The patent focuses on the specific technical parameters used in each process.

[0005] Patent No. CN110788263B discloses a manufacturing process for a stainless steel oil rail forging, which includes seven steps: blanking, heating, blank making, pre-forging, finish forging, trimming, and post-forging treatment. The patent focuses on the design steps of the blank in the blank making process, including four steps: cross-section calculation, cross-section optimization, equivalent cross-section radius determination, and blank shape drawing.

[0006] The above manufacturing processes all use multi-step hot die forging to form stainless steel oil rails, but do not disclose the design method of the preform. In actual production, the design of the preform directly affects the quality level of the finish forging. If the preform is designed unreasonably, the finish forging may have edge collapse, skin clamping, flow line disorder, and even cause the finish forging die to crack. Therefore, it is very important to design the preform scientifically and reasonably.

[0007] When designing the pre-forging die, no compensation design is performed, and the forgings manufactured have large closing error. To ensure that the closing error meets the requirements, the die generally needs to be added with guide columns, which is complex in design and high in manufacturing cost. For easily deformed parts, a shaping process is often added in the later stage to ensure the position or contour. Although the manufacturing process disclosed in CN111590004B increases compensation in the trimming process, the spring has a low service life at high temperature and is high in use cost. Moreover, the compensation of the patent only compensates for the easily deformed parts, and cannot solve the problem of closing error. SUMMARY

[0008] The present application aims to provide an oil rail pre-forging design method and a die designed by using the method to solve the problems in the background art.

[0009] To achieve the above object, the present application provides the following technical solution: an oil rail pre-forging design method, comprising the following steps:

[0010] S1, pre-forging design;

[0011] S2, pre-forging weight analysis: analyze whether the pre-forging weight is greater than the finish-forging weight, if the analysis is "no", optimize the pre-forging and redesign the pre-forging in S1;

[0012] S3, pre-forging die design;

[0013] S4, numerical simulation;

[0014] S5, simulation result analysis: whether there is a defect, if there is a defect, optimize the pre-forging and redesign the pre-forging in S1;

[0015] S6, when there is no defect, the design is completed.

[0016] Preferably, in S1, the pre-forging design comprises the following steps:

[0017] S1.1, main oil pipe design;

[0018] S1.2, branch component design;

[0019] S1.3, transition fillet design;

[0020] S1.4, compensation judgment.

[0021] Preferably, in S1.2, the branch component includes a support, an oil injector seat, and a joint; when the branch component is designed, the pre-forging branch diameter is 0.6-1mm smaller than the corresponding finish-forging diameter; the pre-forging branch length is 1.0-2.0mm longer than the finish-forging length; the specific length L 预锻枝杈 can be calculated by the following formula:

[0022] L 预锻枝杈 = (1.03-1.08V 精锻枝杈 ) / S 预锻枝杈

[0023] Wherein, V 精锻枝杈 is the volume of the finish-forging branch, S 预锻枝杈 is the base area of the pre-forging branch; the draft angle of the pre-forging branch is 2°-4° larger than that of the finish-forging.

[0024] In S1.4, the deformable part is analyzed, especially the thinner part; in the design of the pre-forging part, the corresponding reverse compensation is made according to the deformation direction to ensure that the product is not deformed after the fine-forging cutting edge; the mold closing error is judged, and the corresponding compensation is made in the mold design.

[0025] Preferably, in S1.1, the pre-forging main oil pipe diameter adopts the following scheme:

[0026] The pre-forging main oil pipe diameter is circular, and the pre-forging main oil pipe diameter D1 is 0.6-1.0 mm larger than the fine-forging main oil pipe diameter D2.

[0027] Preferably, in S1.1, the pre-forging main oil pipe diameter adopts the following scheme:

[0028] The pre-forging main oil pipe diameter is elliptical, the pre-forging main oil pipe radius R1 is equal to the fine-forging main oil pipe radius R2, and the pre-forging main oil pipe thickness H1 is 0.8-1.2 mm thicker than the fine-forging main oil pipe diameter D2.

[0029] Preferably, the pre-forging main oil pipe length is 0.5-1.0 mm shorter than the fine-forging main oil pipe length on one side, and the pre-forging main oil pipe draft angle at both ends is 2°-4° larger than the fine-forging main oil pipe draft angle at both ends.

[0030] Preferably, in S2, in order to ensure that the fine-forging part can be filled without collapse, the pre-forging part weight is set to be 3%-8% larger than the fine-forging part weight; the weight of the pre-forging part and the fine-forging part is measured by three-dimensional modeling software:

[0031] Δm=(M 预锻 -M 精锻 ) / M 精锻 ×100%

[0032] Δm is the mass percentage of the pre-forging part greater than the fine-forging part, M 预锻 represents the mass of the pre-forging part, and M 精锻 represents the mass of the fine-forging part.

[0033] Preferably, in S3, when designing the pre-forging mold, the forging part is first scaled; the scaling factor is selected to be 1.0185-1.02; the flash thickness h is 2.0-3.0 mm, the flash bridge length L is 12-15 mm, the flash bin height H is 8-12 mm, and the transition angle α of the flash bridge and the flash bin is 40°-50°;

[0034] In order to facilitate the clamping and automation of the forging part, the pre-forging lower die is provided with a ejector pin hole; in order to prevent the forging part from sticking to the mold during pre-forging, the pre-forging upper die is provided with an ejector pin hole; the pre-forging mold material uses H13, and the heat treatment hardness is HRC45-49.

[0035] Preferably, in S4, the three-dimensional modeling software designed mold is imported into the numerical simulation software for oil rail forming simulation; in the simulation setting, the minimum edge length of the blank grid is set to 0.65-0.8mm, and the step is less than 1 / 3 of the minimum edge length to ensure easy convergence during simulation;

[0036] In S5, after the simulation in S4 is completed, the post-processing interface of the simulation software is entered to analyze whether there are flow line disorder, folding and underfill defects in the simulation process.

[0037] In addition, the present application also provides a mold designed by the oil rail preform design method, comprising a preforming lower die and a preforming upper die, wherein the preforming lower die and the preforming upper die both comprise a ejector pin hole, a main oil pipe cavity, a small ear cavity and a branch component; the branch component comprises a joint cavity, an oil injector seat cavity and a support cavity; the oil injector seat cavity and the support cavity are a group and are located on the same side of the main oil pipe cavity; the small ear cavity is two and is arranged on the same side of the main oil pipe cavity which is opposite to the oil injector seat cavity, and the joint cavity is located on the same side of the main oil pipe cavity as the oil injector seat cavity.

[0038] Compared with the prior art, the present application has the following technical effects:

[0039] Using the method, the oil rail preform can be quickly designed, and combined with numerical simulation, the phenomena such as edge collapse, skin folding, flow line disorder and precision forging mold cracking can be effectively avoided. The mold designed by the oil rail preform design method can reduce the number of product tests, shorten the product development cycle, and thus reduce the product development cost. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0041] Figure 1 The flowchart of the present application;

[0042] Figure 2 The preform main oil pipe designed as a circular structure of the present application;

[0043] Figure 3 The preform main oil pipe designed as an elliptical structure of the present application;

[0044] Figure 4 The flash structure of the preform mold of the present application;

[0045] Figure 5 Schematic diagram of small ear structure of the present application;

[0046] Figure 6 Schematic diagram of lower ejector pin hole structure of the present application;

[0047] Figure 7 Schematic diagram of upper ejector pin hole structure of the present application;

[0048] Figure 8 Schematic diagram of force analysis during die assembly of the present application;

[0049] Figure 9 Schematic diagram of pre-forging lower die and pre-forging upper die structure of the present application;

[0050] Figure 10 Schematic diagram of oil rail pre-forging structure of the present application;

[0051] Figure 11 Schematic diagram of simulation of contact between forging surface and die cavity, no edge collapse and underfilling of the present application.

[0052] BRIEF DESCRIPTION OF DRAWINGS: 1, pre-forging lower die; 2, pre-forging upper die; 3, ejector pin hole; 4, main oil pipe cavity; 5, joint cavity; 6, small ear cavity; 7, oil injector seat cavity; 8, bracket cavity. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0054] Embodiment 1

[0055] Please refer to Figures 1-11 The present application provides a technical solution: a design method of oil rail pre-forging, comprising the following steps:

[0056] S1, pre-forging design

[0057] S1.1, main oil pipe design

[0058] The pre-forging main oil pipe diameter has two schemes, as shown in Figure 2 and Figure 3 Scheme one is circular, as shown in Figure 2 The pre-forging main oil pipe diameter D1 is 0.6-1.0 mm larger than the finish-forging main oil pipe diameter D2.

[0059] Scheme two is elliptical, as shown in Figure 3As shown, the pre-forging main oil pipe radius R1 is equal to the fine-forging main oil pipe radius R2, and the pre-forging main oil pipe thickness H1 is 0.8-1.2mm thicker than the fine-forging main oil pipe diameter D2.

[0060] The pre-forging main oil pipe length is 0.5-1.0mm shorter than the fine-forging main oil pipe length on one side, and the pre-forging main oil pipe two-end draft is 2°-4° larger than the fine-forging main oil pipe two-end draft.

[0061] S1.2, branch component design

[0062] The branch component mainly includes a support, an oil injector seat, a joint, etc. When the branch component is designed, the pre-forging branch diameter should be 0.6-1mm smaller than the corresponding fine-forging diameter. The pre-forging branch length should be 1.0-2.0mm longer than the fine-forging length. The specific length L 预锻枝杈 can be calculated by the following formula:

[0063] L 预锻枝杈 =(1.03~1.08V 精锻枝杈 ) / S 预锻枝杈

[0064] Wherein, V 精锻枝杈 is the volume of the fine-forging branch, and S 预锻枝杈 is the bottom area of the pre-forging branch. The pre-forging branch draft should be 2°-4° larger than the fine-forging.

[0065] S1.3, transition fillet design

[0066] S1.4, compensation judgment

[0067] The variable deformation part is analyzed, especially the thinner part. In the design of the pre-forging part, according to the deformation direction, the corresponding reverse compensation is carried out to ensure that the product does not deform after the fine-forging cutting edge. The die design is judged, and the corresponding compensation is made.

[0068] S2, pre-forging weight analysis: whether the pre-forging weight is greater than the fine-forging weight, if the analysis is "no", the pre-forging is optimized to re-design the pre-forging in S1;

[0069] In order to ensure that the fine-forging part can be filled without collapse, the pre-forging weight should be 3%-8% greater than the fine-forging weight. The weight of the pre-forging and the fine-forging can be measured by three-dimensional modeling software.

[0070] Δm=(M 预锻 -M 精锻 ) / M 精锻 ×100%

[0071] Δm is the mass ratio of the pre-forging being greater than the fine-forging, M 预锻 represents the mass of the pre-forging, and M精锻 The quality of the finish forging piece is represented.

[0072] If Δm < 3%, the finish forging is not full, the collapse appears, or the finish forging thickness exceeds the lower difference, which cannot meet the drawing requirements.

[0073] If Δm > 8%, the finish forging material is too much, the die life is low, or the finish forging thickness exceeds the upper difference, which cannot meet the drawing requirements.

[0074] S3, pre-forging piece die design

[0075] When the pre-forging die is designed, the forging piece should be scaled first. The scaling factor is generally selected as 1.0185-1.02; the oil rail is generally made of stainless steel material, and the deformation resistance of the stainless steel material is large and the viscosity is strong. In order to reduce the forging forming force and improve the service life of the die, the pre-forging generally adopts open forging. The flash design of the open pre-forging die of the stainless steel oil rail is shown in Figure 4 The flash thickness h is generally 2.0-3.0 mm, the flash bridge length L is 12-15 mm, the flash pocket height H is 8-12 mm, and the transition angle a of the flash bridge and the flash pocket is 40°-50°.

[0076] In order to facilitate the clamping of the forging piece and automation, the pre-forging lower die is provided with a ejector pin hole; in order to prevent the forging piece from sticking to the upper die during pre-forging, the pre-forging upper die is provided with a ejector pin hole. The pre-forging die material is generally H13 or equivalent material, and the heat treatment hardness is HRC45-49.

[0077] S4, numerical simulation

[0078] The die designed by the three-dimensional modeling software is imported into the numerical simulation software to simulate the forming of the oil rail. When the simulation is set, the minimum edge length of the blank grid is set to 0.65-0.8 mm, and in order to ensure easy convergence during simulation, the step length should be less than 1 / 3 of the minimum edge length.

[0079] S5, simulation result analysis: whether there is a defect, if there is a defect, optimize the pre-forging piece and re-design the pre-forging piece in S1;

[0080] After the simulation is completed, the post-processing interface of the simulation software is entered, and whether there are defects such as flow line disorder, folding and underfilling in the simulation process is analyzed.

[0081] S6, if there is no defect, the pre-forging die design is completed.

[0082] Example 2

[0083] Please refer to Figures 1-11The application also provides a die designed according to the oil rail preform design method, comprising a preform lower die 1 and a preform upper die 2, wherein the preform lower die 1 and the preform upper die 2 each comprise a ejector rod hole 3, a main oil pipe cavity 4, a small ear cavity 6 and a branch component; the branch component comprises a joint cavity 5, an oil injector seat cavity 7 and a support cavity 8; the oil injector seat cavity 7 and the support cavity 8 are a group and are located on the same side of the main oil pipe cavity 4; the small ear cavity 6 is two and is located on the same side of the main oil pipe cavity 4 which is opposite to the oil injector seat cavity 7, and the joint cavity 5 is located on the same side of the main oil pipe cavity 4 as the oil injector seat cavity 7.

[0084] Wherein, the ejector rod hole 3 is used for inserting an ejector rod, the main oil pipe cavity 4 is used for manufacturing a main oil pipe, the joint cavity 5 is used for manufacturing a joint, the small ear cavity 6 is used for manufacturing a small ear, the oil injector seat cavity 7 is used for manufacturing an oil injector seat, and the support cavity 8 is used for manufacturing a support.

[0085] The die design method is as follows:

[0086] 1) Preform design: the preform main oil pipe is designed in a circular shape, as shown in Figure 2 , the preform main oil pipe diameter is 0.8mm larger than that of the finish forging, the preform main oil pipe length is 0.7mm shorter than that of the finish forging single side, and the preform main oil pipe two-end draft is 7°. The branch component mainly comprises a support, an oil injector seat, a joint and the like. When the branch component is designed, the preform branch diameter is 0.8mm smaller than that of the corresponding finish forging. The preform branch length is calculated through the following formula:

[0087] L 预锻枝杈 =1.05V 精锻枝杈 / S 预锻枝杈

[0088] The branch draft is 5°.

[0089] Compensation judgment: the oil rail has two small ears, and the small ears are relatively thin, as shown in Figure 5 . When the edge is cut, the small ears are subjected to upward tension, so after the edge is cut, the small ears will be warped and deformed upward. Therefore, when the preform is designed, the small ear of the preform should be reversely compensated, that is, the preform small ear angle β1 satisfies:

[0090] β1=β-1.5°

[0091] 2) Preform weight analysis: using a three-dimensional modeling software, the weights of the preform and the finish forging are analyzed, M 预锻 is 1.23kg, and M 精锻 is 1.17kg.

[0092] Δm=(M 预锻 -M 精锻 ) / M 精锻 ×100%=5.13%

[0093] Δm is between 3% and 8%, satisfying the design requirements.

[0094] 3) Pre-forging die design: when designing the pre-forging die, the forging should be scaled first. The scaling factor is selected as 1.0195. The flash of the open pre-forging die of the stainless steel oil rail is designed according to Figure 4 . The thickness h of the flash is 2.5 mm, the length L of the flash bridge is 14 mm, the height H of the flash pocket is 10 mm, and the transition angle a of the flash bridge and the flash pocket is 45°. In order to facilitate the clamping of the forging, the pre-forging lower die 1 is provided with four ejector pin holes 3; in order to prevent the forging from sticking to the die during pre-forging, the pre-forging upper die 2 is provided with four ejector pin holes 3, and the pre-forging upper die 2 and the pre-forging lower die 1 are obtained as shown in Figure 9 . The die material is H13, and the heat treatment hardness is HRC 45-49.

[0095] In order to facilitate the processing of the ejector pin hole 3, the ejector pin hole 3 of the pre-forging lower die 1 adopts a stepped structure, as shown in Figure 6 . The upper end diameter of the ejector pin hole 3 of the pre-forging lower die 1 is ΦDa, the lower end diameter is ΦDb, and the upper end port of the ejector pin hole 3 is chamfered with Ra.

[0096] The structure of the ejector pin hole 3 of the pre-forging upper die 1 is shown in Figure 7 . The ejector pin hole 3 of the pre-forging upper die 1 is provided with a spring groove with a diameter of ΦDc. In order to prevent the die from cracking along the ejector pin hole during use, the root of the spring groove is chamfered with Rb; the middle part of the ejector pin hole 3 of the pre-forging upper die 1 has a diameter of ΦDb, the lower end has a diameter of ΦDa, and the lower end port of the ejector pin hole 3 is chamfered with Ra.

[0097] When the pre-forging upper die is closed, the stress analysis is shown in Figure 8 . Due to the action of the component force F2, the upper die will be misaligned to the right during forging. In order to ensure that the misalignment amount of the forging meets the requirements, the pre-forging lower die cavity should be appropriately compensated to the right, and the compensation amount is 0.1-0.6.

[0098] 4) Numerical simulation: the above designed die is exported in stl format and imported into the numerical simulation software for simulation. The number of blank mesh is set to 70000, the minimum edge length of the mesh is 0.71 mm, and the step length is set to 0.2 mm.

[0099] 5) Analysis of simulation results: after the simulation is completed, enter the post-processing interface of the simulation software to analyze whether there are defects such as flow line disorder, folding and underfilling in the simulation process. It can be known from the simulation that the flow line is clear, there is no turbulence and folding, as shown in Figure 8 . At the end of the simulation, the surface of the forging is in full contact with the die cavity, and there is no collapse and underfilling, as shown in Figure 11 . According to the simulation, the forging has no defects, so the pre-forging design is reasonable, and the pre-forging die design is completed.

[0100] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above-described is only a specific embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An oil rail preform design method characterized by, It comprises the following steps: S1, pre-forging design: the pre-forging design comprises the following steps: S1.1, main oil pipe design; S1.2, branch type component design: the branch type components include support, oil injector seat, joint; when designing the branch type components, the diameter of the preform branch is 0.6-1 mm smaller than the diameter of the corresponding finish-forged piece; the length of the preform branch is 1.0-2.0 mm longer than the finish-forged piece; the specific length L 预锻枝杈 This can be calculated by the following formula: L 预锻枝杈 = (1.03 - 1.08V 精锻枝杈 ) / S 预锻枝杈 wherein V 精锻枝杈 is the volume of the branch of the finish-forged piece, S 预锻枝杈 is the base area of the branch of the pre-forged piece; the draft of the pre-forged branch is 2° to 4° greater than the finish-forged piece. S1.3, transition fillet design; S1.4, compensation judgment: analysis of small ears; when designing the pre-forging, according to the deformation direction, the corresponding reverse compensation is carried out to ensure that the product is not deformed after the fine forging cutting edge; the mold closing error is judged, and the corresponding compensation is made in the mold design; S2, pre-forging weight analysis: analyze whether the pre-forging weight is greater than the fine forging weight, if the analysis is "no", optimize the pre-forging and re-design the pre-forging in S1; in order to ensure that the fine forging is full and has no collapse, the pre-forging weight is set to be 3%-8% greater than the fine forging weight; the weight of the pre-forging and the fine forging is measured by three-dimensional modeling software: Δm = (M 预锻 - M 精锻 ) / M 精锻 x 100% Δm is the mass ratio of the pre-forging part to the finish-forging part, M 预锻 M represents the mass of the pre-forging part 精锻 M represents the mass of the finish-forging part S3, pre-forging die design: the die comprises a pre-forging lower die (1) and a pre-forging upper die (2), the pre-forging lower die (1) and the pre-forging upper die (2) both comprise a ejector pin hole (3), a main oil pipe cavity (4), a small ear cavity (6) and a branch component; the branch component comprises a joint cavity (5), an oil injector seat cavity (7) and a support cavity (8); the oil injector seat cavity (7) and the support cavity (8) are a group and are located on the same side of the main oil pipe cavity (4); the small ear cavity (6) is two and is arranged on the same side of the main oil pipe cavity (4) which faces away from the oil injector seat cavity (7), and the joint cavity (5) is located on the same side of the main oil pipe cavity (4) and the oil injector seat cavity (7); when designing the pre-forging die, the forging is scaled first; the scaling coefficient is selected to be 1.0185-1.02; the flash thickness h is 2.0-3.0mm, the flash bridge length L is 12-15mm, the flash pocket height H is 8-12mm, and the transition angle α of the flash bridge and the flash pocket is 40°-50°; In order to facilitate the clamping and automation of the forging, the pre-forging lower die is provided with an ejector pin hole; in order to prevent the forging from sticking to the die during pre-forging, the pre-forging upper die is provided with an ejector pin hole; the pre-forging die material uses H13, and the heat treatment hardness is HRC45-49; S4, numerical simulation: when numerical simulation is carried out, the die designed by the three-dimensional modeling software is imported into the numerical simulation software to simulate the forming of the oil rail; when the simulation is set, the minimum edge length of the blank grid is set to be 0.65-0.8mm; in order to ensure easy convergence during simulation, the step length is less than 1 / 3 of the minimum edge length; S5, simulation result analysis: whether there is a defect, if there is a defect, optimize the pre-forging and re-design the pre-forging in S1; after the simulation is completed by S4, enter the post-processing interface of the simulation software, and analyze whether there is flow line disorder, folding and underfilling defect in the simulation process; S6, when there is no defect, the design is completed.

2. A method of designing an oil rail preform according to claim 1, wherein: In S1.1, the pre-forging main oil pipe diameter adopts the following scheme: The pre-forging main oil pipe diameter is circular, and the pre-forging main oil pipe diameter D1 is 0.6-1.0mm larger than the fine forging main oil pipe diameter D2.

3. The method of designing an oil rail preform according to claim 1, wherein: In S1.1, the pre-forging main oil pipe diameter adopts the following scheme: The pre-forging main oil pipe is elliptical in shape, the radius R1 of the pre-forging main oil pipe is equal to the radius R2 of the fine-forging main oil pipe, and the thickness H1 of the pre-forging main oil pipe is 0.8-1.2 mm thicker than the diameter D2 of the fine-forging main oil pipe.

4. A method of designing an oil rail preform according to any one of claims 2 or 3, wherein: The length of the pre-forging main oil pipe is 0.5-1.0 mm shorter than the length of the fine-forging main oil pipe on one side, and the draft angle of the pre-forging main oil pipe is 2-4° larger than the draft angle of the fine-forging main oil pipe on both ends.

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