Method for manufacturing an integral fuel rail

Abstract

The present invention relates to the technical field of fuel rails and discloses a method for manufacturing an integral fuel rail, comprising the following steps: S1, first determining whether a fuel injection hole of the fuel rail can be machined, and then connecting a fuel injector seat cavity to an inner cavity of a main fuel pipe by a through hole; S2, after the position and depth of the fuel injector seat are determined, entering the forging design process. In the integral fuel rail manufacturing method, the fuel injection hole should be located below the axis of the main fuel pipe, and the tool for machining the hole should not interfere with the fuel injector mounting seat. If there is interference or the fuel injection hole cannot be penetrated, the fuel injector mounting seat needs to be optimized to reduce the center distance between the fuel injector mounting seat and the main fuel rail; the end face of the fuel injector seat mouth is moved to reduce the depth of the fuel injector seat cavity. When designing the forging, the machined surface and the non-machined surface are first determined, and appropriate allowances are left for surfaces that need to be machined. The machining allowances required for different parts should meet the following requirements: an allowance of 1.2-1.5 mm for the end face and an allowance of 1 mm-1.2 mm on one side for the outer circle, thereby avoiding a large number of defective products.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel rails, and in particular to a method for manufacturing an integral fuel rail. Background Art

[0002] Vehicle exhaust is a significant source of air pollution. The China VI emission regulations were introduced to monitor vehicle emissions during actual driving. To meet these standards, increasing the operating pressure of the fuel injection system is the most common approach. This increased fuel pressure also places higher demands on the sealing performance of fuel lines. Currently, the main methods for forming fuel lines are brazing and integral forging. Brazed rails are further categorized as fully brazed and semi-brazed. The fully brazed rail process is complex, requiring the main fuel line, injector seat, bracket, sensor connector, and other components to be machined and then laser welded or brazed together. Semi-brazed rails, on the other hand, have the injector seat or bracket brazed onto the rail body.

[0003] According to the description of patent application number "CN202010454531.3 A manufacturing process for integral stainless steel oil rail forgings", "In the first aspect, an embodiment of the present invention provides an integral stainless steel oil rail forging, the straightness of the main pipe part of the forging does not exceed 0.6mm, and the position accuracy does not exceed 1mm. In the second aspect, an embodiment of the present invention provides a manufacturing process for manufacturing an integral stainless steel oil rail forging, which is specifically as follows: A manufacturing process for manufacturing an integral stainless steel oil rail forging, characterized in that it includes the following steps: S1 blanking, S2 heating, S3 die forging, S4 trimming, S5 post-forging treatment, wherein a trimming correction composite die is adopted, wherein the trimming correction composite die structure of the stainless steel oil rail forging includes: an upper die assembly and a lower die assembly, the upper die assembly includes a stripper plate, a punch, a stripper elastic member and a stripper fixing member, the stripper elastic member is placed In the unloading fixing part, the lower die assembly includes a lower die base core, a floating plate and a lower elastic part. The lower die base core is fixed to the floating plate. The lower elastic part is connected to the bottom of the floating plate. The deformation compensation amount is increased by a punch, and the compensation amount is ±0.3mm. The trimming is performed by a press, the pressure is controlled below 250t, and the temperature is controlled between 800-900 degrees Celsius. The single-side gap between the lower die base core and the cutting edge of the trimming lower die is controlled within 0.2mm. During trimming, the hot stainless steel oil rail forging product with flash is placed in the lower die base core. After starting the equipment, the punch first contacts the hot stainless steel oil rail forging product and moves with the lower die assembly. When the flash of the hot stainless steel rail forging product is cut off, the equipment returns, and the lower elastic part presses the floating plate to move upward, ejecting the product from the trimming lower mold cavity, and taking out the hot stainless steel rail forging product.

[0004] According to the above patent, the finished fuel rail obtained according to the existing process is prone to uneven wall thickness, which will further cause oil leakage in the thin-walled parts of the fuel rail during actual service, reducing its reliability under high working pressure. The process uses a trimming correction composite die and adds appropriate compensation to the die to avoid deformation of the fuel rail during the forging process. Although the brazed fuel rail brazes the main fuel pipe, injector seat, bracket and other components into a whole, the mechanical properties of the components are unevenly distributed, and there are several welds on it. Under high pressure of 250Mpa and above, the reliability is low and it is very easy to cause leakage. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In view of the shortcomings of the existing technology, the present invention provides an integral fuel rail manufacturing method, which has the advantage of increasing the structural stability of the fuel rail and solving the problem of low reliability and easy leakage in the existing fuel rail manufacturing process.

[0007] (2) Technical solution

[0008] To achieve the above-mentioned object, the present invention provides the following technical solutions: a method for manufacturing an integral fuel rail, comprising the following steps;

[0009] S1: First, determine whether the fuel rail's injection hole can be machined. Then, the injector seat cavity and the main oil pipe cavity are connected by a through hole. In S1, the injection hole should be located below the main oil pipe axis, and the tool used to machine the hole should not interfere with the injector seat.

[0010] S2. After the injector seat position and depth are determined, the forging design is started. When designing the forging, the machined and non-machined surfaces are first determined, and appropriate allowances are left for the surfaces that need to be machined. The machining allowances required for different parts should meet the following requirements: an allowance of 1.2-1.5mm for the end face and 1mm-1.2mm for the outer circle on one side.

[0011] S3, parting line design. There are generally two types of parting lines: horizontal parting and stepped parting. To facilitate metal flow during forging, the parting line should be as simple as possible;

[0012] S4, draft angle design. After the parting line is designed, the injector seat, bracket, sensor connector and both ends of the oil rail are drafted. The draft angle α is generally selected to be 3-7°;

[0013] S5. After the above steps, a forging with flash is obtained. Modeling software is used to analyze the slope of the forging. No negative angle is allowed. The flash is removed to obtain the initial forging.

[0014] S6. Design the machined parts. Based on the locations of the injector seat, bracket, sensor connector, and main oil pipe holes in the brazed parts, design holes on the forgings that match them. The outer diameters of the injector mounting seat and bracket should be 1mm-1.5mm larger than those of the brazed parts. The diameter of the main oil rail should be 0.2-0.5mm larger than that of the brazed parts.

[0015] S7, determine whether the machined part has steps and burrs, and the oil rail is completed.

[0016] Preferably, in the S6, the size of the fuel rail will fluctuate during the forging and machining process, in order to ensure the minimum wall thickness of the injector seat and the bracket hole after machining.

[0017] Preferably, in S4, in order to ensure machining allowance, when the injector seat and the bracket side are drafted, they should be drafted outwards based on the bottom surface, and the upper and lower quadrant points at both ends of the oil rail should be drafted outwards based on the upper and lower quadrant points.

[0018] Preferably, the oil rail includes a main oil pipe main oil rail,

[0019] End surfaces are provided at both ends of the main oil pipe and the main oil rail;

[0020] A fuel injector mounting seat is longitudinally arranged on the outer side wall of the main fuel pipe and main fuel rail;

[0021] The sensor connector is arranged on the outer side wall of the main oil pipe and main oil rail.

[0022] Preferably, a boss is provided on one side of the top of the injector mounting seat.

[0023] Preferably, a slope is provided on one side of the top of the injector mounting seat.

[0024] Preferably, one side of the injector mounting seat is provided with a rounded corner.

[0025] Preferably, the end face allowance is 1.2-1.5 mm, and the outer circle allowance is 1 mm-1.2 mm on one side.

[0026] (3) Beneficial effects

[0027] Compared with the prior art, the present invention provides a method for manufacturing an integral fuel rail, which has the following beneficial effects:

[0028] This integral oil rail manufacturing method stipulates that the injection hole should be located below the axis of the main oil pipe, and the tool for machining the hole should not interfere with the injector mounting seat. If there is interference or the injection hole cannot be penetrated, the injector mounting seat needs to be optimized to reduce the center distance between the injector mounting seat and the main oil rail; the end face of the injector seat mouth is moved to reduce the depth of the injector seat cavity. When designing the forging, the machined surface and non-machined surface are first determined, and appropriate allowances are left for the surfaces that need to be machined. The required machining allowances for different parts should meet the following requirements: an allowance of 1.2-1.5mm for the end face and an allowance of 1mm-1.2mm on one side for the outer circle. This can avoid a large number of defective products. The size of the oil rail will fluctuate during the forging and machining process. To ensure the minimum wall thickness of the injector seat and bracket hole after machining, when designing the forging, the outer diameter of the injector seat and the outer diameter of the bracket should be 1mm-1.5mm larger than the brazed part. When the main oil pipe is under low pressure, the outer diameter of the forged rail main oil pipe is the same as the outer diameter of the brazed rail. When the main oil pipe is under high pressure, the diameter of the forged main oil pipe should be 0.2-0.5mm larger than the brazed part. In order to facilitate positioning and clamping during deep hole processing of the main oil rail, a boss is designed at both ends of the oil rail. The outer diameter D of the boss is generally selected from Φ25-Φ27mm, and the boss length H is generally selected from 8-10mm. In order to prevent burrs from forming at the transition between the boss and the main oil rail after the outer circle of the boss is processed, the transition should be connected with a bevel. The bevel angle β is generally selected from 25°-35°, and the corner is cut. This can effectively save materials and reduce the weight of the oil rail. When a stepped parting is selected, the parting line drop is preferably less than 10mm, and a bevel transition is used at the step. The bevel angle is determined according to the drop size. In order to facilitate metal flow, the transition bevel should be gentle, generally 30°-60°. The flash thickness of the main oil rail A suitable thickness is generally 2.5-3mm. The injector mount, main fuel rail, and sensor connector are connected as a single unit with a fillet transition, typically R5-R7. Using the design method of the present invention, a brazed fuel rail can be converted to a monolithic forged rail. This integral forging process effectively reduces the number of components. The outer diameters of the injector mount and bracket are 1mm-1.5mm larger than those of the brazed components, while the main fuel rail diameter should be 0.2-0.5mm larger than the brazed components. This effectively ensures the minimum wall thickness of the injector mount and main fuel rail after machining. The design steps of this monolithic forged rail primarily include determining whether the injector mount's injection hole can be machined, designing the forging, designing the parting line, designing the draft angle, designing the machined component, and determining whether the machined component has steps or burrs. This significantly improves the safety, reliability, and stability of the main fuel rail when operating at high pressures exceeding 250MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the preparation process of the present invention;

[0030] Figure 2 Schematic diagram of the structure of the main oil pipe in the present invention;

[0031] Figure 3 It is a structural schematic diagram of the side surface of the main oil pipe in the present invention.

[0032] In the picture:

[0033] 11. Main fuel rail; 12. End face; 13. Injector mounting seat; 14. Sensor connector; 15. Boss; 16. Inclined surface; 17. Fillet. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] Example

[0036] A method for manufacturing an integral fuel rail comprises the following steps:

[0037] S1: First, determine whether the fuel rail's injection hole can be machined. Then, the injector seat cavity and the main oil pipe cavity are connected by a through hole. In S1, the injection hole should be located below the main oil pipe axis, and the tool used to machine the hole should not interfere with the injector seat.

[0038] S2. After the injector seat position and depth are determined, the forging design is started. When designing the forging, the machined and non-machined surfaces are first determined, and appropriate allowances are left for the surfaces that need to be machined. The machining allowances required for different parts should meet the following requirements: an allowance of 1.2-1.5mm for the end face and 1mm-1.2mm for the outer circle on one side.

[0039] S3, parting line design. There are generally two types of parting lines: horizontal parting and stepped parting. To facilitate metal flow during forging, the parting line should be as simple as possible;

[0040] S4, draft angle design. After the parting line is designed, the injector seat, bracket, sensor connector and both ends of the oil rail are drafted. The draft angle α is generally selected to be 3-7°;

[0041] S5. After the above steps, a forging with flash is obtained. Modeling software is used to analyze the slope of the forging. No negative angle is allowed. The flash is removed to obtain the initial forging.

[0042] S6. Design the machined parts. Based on the locations of the injector seat, bracket, sensor connector, and main oil pipe holes in the brazed parts, design holes on the forgings that match them. The outer diameters of the injector mounting seat and bracket should be 1mm-1.5mm larger than those of the brazed parts. The diameter of the main oil rail should be 0.2-0.5mm larger than that of the brazed parts.

[0043] S7, judging whether the machined part has steps and burrs, and thus the oil rail is manufactured;

[0044] The S6, the oil rail will fluctuate in size during the forging and machining process. To ensure the minimum wall thickness of the injector seat and bracket hole after machining, the S4, to ensure the machining allowance, the injector seat and bracket side should be drafted outwards with the bottom surface as the reference, and the upper and lower quadrant points at both ends of the oil rail are respectively drafted outwards. The oil rail includes a main oil pipe main oil rail 11, and an end surface 12, which is provided at both ends of the main oil pipe main oil rail 11; the injector mounting seat 1 3, longitudinally arranged on the outer wall of the main oil pipe and main oil rail 11; the sensor connector 14 is arranged on the outer wall of the main oil pipe and main oil rail 11; a boss 15 is provided on one side of the top of the injector mounting seat 13, a bevel 16 is opened on one side of the top of the injector mounting seat 13, and a rounded corner 17 is provided on one side of the injector mounting seat 13; the end surface 12 has a margin of 1.2-1.5mm, and the outer circle margin is 1mm-1.2mm on one side;

[0045] See Figure 1-3The injection hole should be located below the axis of the main oil pipe, and the tool for machining the hole should not interfere with the injector mounting seat 13. If there is interference or the injection hole cannot be penetrated, the injector mounting seat 13 needs to be optimized and the center distance between the injector mounting seat 13 and the main oil rail 11 needs to be reduced; move the end face of the injector seat mouth to reduce the depth of the injector seat cavity. When designing forgings, first determine the machined surface and non-machined surface, and leave appropriate allowances for the surfaces that need to be machined. The machining allowances required for different parts should meet the following requirements: 1.2-1.5mm allowance for the end face and 1mm-1.2mm allowance for one side of the outer circle. This can avoid a large number of defective products. The size of the oil rail will fluctuate during the forging and machining process. To ensure the minimum wall thickness of the injector seat and the bracket hole after machining, when designing forgings, the outer diameter of the injector seat and the outer diameter of the bracket should be 1mm-1.5mm larger than the brazed part. When the main oil pipe is under low pressure, the outer diameter of the forged rail main oil pipe is the same as the outer diameter of the brazed rail. When the main oil pipe is under high pressure, the diameter of the forged main oil pipe should be 0.2-0.5mm larger than the brazed part. In order to facilitate the positioning and clamping of the main oil rail 11 during deep hole processing, a boss 15 is designed at both ends of the oil rail. The outer diameter D of the boss 15 is generally selected from Φ25-Φ27mm, and the length H of the boss 15 is generally selected from 8-10mm. In order to prevent the boss 15 from being too close to the main oil rail 11 after the outer circle is processed, the boss 15 is not too close to the main oil rail 11. The transition should be connected by a bevel 16. The angle β of the bevel 16 is generally selected to be 25°-35°, and the angle should be cut to save materials and reduce the weight of the oil rail. When the stepped parting is selected, the parting line drop should be less than 10mm. At the step, the bevel 16 transition should be used. The angle of the bevel 16 is determined according to the drop size. In order to facilitate the flow of metal, the transition bevel 16 should be gentle, generally 30°-60° is appropriate. The flash of the main oil rail 11 A thickness of 2.5-3 mm is generally preferred. The injector mounting base 13, main fuel rail 11, and sensor connector 14 are connected as a single unit, with a transition radius 17. The radius 17 is generally R5-R7 in size. Using the design method of the present invention, a brazed fuel rail can be converted to an integral forged rail. This integral forging process effectively reduces the number of components. The outer diameters of the injector mounting base 13 and the bracket are 1 mm-1.5 mm larger than those of the brazed components, while the diameter of the main fuel rail 11 should be 0.2-0.5 mm larger than that of the brazed components. This effectively ensures the minimum wall thickness of the injector mounting base 13 and main fuel rail 11 after machining. The design steps of this integral forged rail primarily include determining whether the injector hole of the injector mounting base 13 can be machined, designing the forging component, designing the parting line, designing the draft angle, designing the machined component, and determining whether the machined component has steps or burrs. This significantly improves the safety, reliability, and stability of the main fuel rail 11 when operating at high pressures exceeding 250 MPa.

[0046] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing an integral fuel rail, characterized by: The following steps are included: S1: First, determine whether the fuel rail's injection hole can be machined. Then, the injector seat cavity and the main oil pipe cavity are connected by a through hole. In S1, the injection hole should be located below the main oil pipe axis, and the tool used to machine the hole should not interfere with the injector seat. S2. After the injector seat position and depth are determined, the forging design is started. When designing the forging, the machined and non-machined surfaces are first determined, and appropriate allowances are left for the surfaces that need to be machined. The machining allowances required for different parts should meet the following requirements: an allowance of 1.2-1.5mm for the end face and 1mm-1.2mm for the outer circle on one side. S3, parting line design. There are generally two types of parting lines: horizontal parting and stepped parting. To facilitate metal flow during forging, the parting line should be as simple as possible; S4, draft angle design. After the parting line is designed, the injector seat, bracket, sensor connector and both ends of the oil rail are drafted. The draft angle α is generally selected to be 3-7°; S5. After the above steps, a forging with flash is obtained. Modeling software is used to analyze the slope of the forging. No negative angle is allowed. The flash is removed to obtain the initial forging. S6. Design the machined parts. Based on the locations of the injector seat, bracket, sensor connector, and main oil pipe holes in the brazed parts, design holes on the forgings that match them. The outer diameters of the injector mounting seat and bracket should be 1mm-1.5mm larger than those of the brazed parts. The diameter of the main oil rail should be 0.2-0.5mm larger than that of the brazed parts. S7, determine whether the machined part has steps and burrs, and the oil rail is completed.

2. The method for manufacturing an integral fuel rail according to claim 1, characterized in that: The dimensions of the S6 fuel rail will fluctuate during the forging and machining process to ensure the minimum wall thickness of the injector seat and bracket hole after machining.

3. The method for manufacturing an integral fuel rail according to claim 1, characterized in that: In order to ensure the machining allowance, the injector seat and the bracket side should be drafted outwards with the bottom surface as the reference when drafting, and the upper and lower quadrant points at both ends of the oil rail should be used as the reference and drafted outwards respectively.

4. An integrated fuel rail, according to any one of claims 1-3, characterized in that: The oil rail includes a main oil pipe and a main oil rail (11), End surfaces (12) are provided at both ends of the main oil pipe and main oil rail (11); A fuel injector mounting seat (13) is longitudinally arranged on the outer side wall of the main fuel pipe and main fuel rail (11); The sensor connector (14) is arranged on the outer side wall of the main oil pipe main oil rail (11).

5. The integrated fuel rail according to claim 4, characterized in that: A boss (15) is provided on one side of the top of the injector mounting seat (13).

6. The integrated fuel rail according to claim 5, characterized in that: A slope (16) is provided on one side of the top of the injector mounting seat (13).

7. The integrated fuel rail according to claim 6, characterized in that: A rounded corner (17) is provided on one side of the injector mounting seat (13).

8. The integrated fuel rail according to claim 7, characterized in that: The end surface (12) has a margin of 1.2-1.5 mm, and the outer circle has a single-side margin of 1 mm-1.2 mm.

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