Special fixture for processing of marine fuel system angle oil injector head

Abstract

This utility model relates to a special fixture for machining angle injector heads for marine fuel systems. The fixture body has a beveled positioning surface with an eccentric hole perpendicular to the bottom surface. The inner diameter of the eccentric hole precisely matches the outer diameter of the non-threaded end of the angle injector head. The bevel angle of the fixture body matches the tilt angle of the angle injector head. The beveled surface of the fixture body has at least two positioning pin holes and threaded holes for positioning and connecting the angle injector head. The positioning pins are inserted between the angle injector head and the fixture body, and the positioning hexagonal bolts pass through the mounting holes of the angle injector head and are tightly screwed into the threaded holes of the fixture body. Compared with the prior art, this utility model has a simple structure, is easy to install, has accurate positioning, high reliability, can achieve stable machining, and can be extended to the angle machining of various similar injector heads.

Description

Technical Field

[0001] This utility model relates to the manufacturing technology of fuel injection system for marine high-power low-speed diesel engines, specifically a precision machining method and special fixture for an angled injector head, which is suitable for high-precision turning of the threaded end of the injector head of MAN MEB / MEC and other models. Background Technology

[0002] With the widespread use of MAN's MEB and MEC models, ensuring the machining quality of high-response and high-reliability fuel injection system components for high-power marine engines has become particularly important. This type of injector head is mounted at an angle on the main engine. Due to the main engine design, the high-pressure fuel line needs to be precisely connected to the angled thread of the injector head to achieve high-pressure fuel transmission. Incorrect angle will cause installation failure and thread seizure due to angular deviation. Therefore, it is necessary to ensure the machining of the thread angle. During machining, a deflection angle method is used to adjust it to be consistent with the center of the CNC lathe, which can complete the machining quickly and reliably. A special fixture needs to be designed to adjust the injector head thread angle to zero degrees with the center of the CNC lathe.

[0003] Existing fuel injector heads require tilted installation, and deviations in the threaded end angle can easily lead to difficulties in installing high-pressure fuel lines and thread seizing. Traditional methods use general-purpose fixtures with angle shims for adjustment, which suffers from cumbersome positioning and poor repeatability. For example, patent document CN221210682U uses expansion joint clamping, but its rigidity is insufficient; patent document CN208803995U's bushing positioning structure is complex and cannot meet the high-precision angle machining requirements of fuel injector heads. Therefore, there is an urgent need for a dedicated fixture and machining method that balances positioning accuracy, rigidity, and ease of operation. Summary of the Invention

[0004] This utility model proposes a special fixture for machining angle injector heads of marine fuel systems. By using a specific fixture, the angle injector head is adjusted to be consistent with the rotation center of the machine tool, so that it can be machined.

[0005] To achieve the above objectives, the technical solution of this utility model is: a special fixture for machining angle injector heads of marine fuel systems, comprising a fixture body, a locating pin, and a locating hexagonal socket head cap screw. The locating surface of the fixture body is an inclined surface with an eccentric hole perpendicular to the bottom surface. The inner diameter of the eccentric hole can precisely fit with the outer diameter of the non-threaded end of the angle injector head. The angle of the inclined surface of the fixture body is consistent with the tilt angle of the angle injector head. The inclined surface of the fixture body is provided with at least two locating pin holes and threaded holes for locating and connecting the angle injector head. The locating pin is inserted between the angle injector head and the fixture body for radial limiting of the angle injector head. The locating hexagonal socket head cap screw passes through the mounting hole of the angle injector head and is tightly screwed into the threaded hole of the fixture body for axially pressing the angle injector head.

[0006] Furthermore, the positions of the positioning pin hole and the threaded hole match the corresponding hole positions of the angle injector head.

[0007] Furthermore, the size of the locating pin matches the size of the locating pin hole on the fixture body and the corresponding hole size of the angle injector head.

[0008] Furthermore, the rear end face of the fixture body is provided with a reference surface that fits against the stepped surface of the CNC lathe jaws, with a flatness of ≤0.01mm.

[0009] Furthermore, the fixture body is made of QT400-18 ductile iron and has undergone aging treatment.

[0010] Furthermore, the fixture body is equipped with a modular interface, allowing for the replacement of adapter blocks with different eccentric hole diameters and bevel angles.

[0011] Furthermore, the surface hardness of the locating pin is ≥HRC58, and the diameter tolerance is H7 grade.

[0012] Furthermore, the preload torque of the positioning hexagon socket bolt is 20-25 N·m, and it is equipped with an anti-loosening washer.

[0013] Compared with the prior art, the advantages of this utility model include: 1) simple structure and easy installation; 2) accurate positioning; 3) high reliability; 4) stable processing; 5) expandable to various types of injector head angle processing. Attached Figure Description

[0014] Figure 1 This is a diagram of the positioning fixture assembly;

[0015] Figure 2 for Figure 1 Sectional view along the middle AA;

[0016] Figure 3 for Figure 1 Centerline BB and sectional view;

[0017] Figure 4 This is a three-dimensional schematic diagram of the main body structure;

[0018] Figure 5 This is the main view of the main structure;

[0019] Figure 6 This is the left view of the main structure;

[0020] Figure 7 for Figure 5 A sectional view along the middle edge BB;

[0021] Figure 8 This is a schematic diagram of a positioning pin;

[0022] Figure 9 This is a schematic diagram of a positioning hexagon socket head cap screw. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] like Figures 1 to 9 As shown in the figure, the present invention provides a special jig for machining the angle injector head of a marine fuel system, including a jig body 1, a positioning hexagon socket bolt 3, and a positioning pin 4.

[0025] The fixture body 1 is provided with an eccentric large hole 1-2, the inner diameter of which is precisely matched with the outer circle of the non-threaded end of the angle injector head 2; the fixture body 1 is provided with an inclined surface 1-1, the angle of which is consistent with the tilt angle of the angle injector head 2; the fixture body 1 is provided with two threaded positioning holes 1-4 and one positioning pin hole 1-3, the positions of which match the corresponding holes of the angle injector head 2.

[0026] In use, the outer circular end face of the fixture body 1 is positioned along its length by touching the stepped surface of the chuck jaw 5 of the CNC lathe. The eccentric large hole 1-2 on the inclined surface of the fixture body 1 is aligned with the outer circle of the non-threaded end of the angle injector head 2. The angle of the inclined surface 1-1 of the fixture body 1 is aligned with the tilt angle of the angle injector 2. The fixture body 1 is provided with two threaded positioning holes 1-4 and one positioning pin hole 1-3. The center distance of the positioning holes and the size and position of the positioning pin are designed to be consistent with the corresponding holes of the angle injector head 2 to ensure positioning and fastening during assembly.

[0027] like Figures 3 to 7 As shown, the fixture body 1 has an off-center eccentric large hole 1-2, which is consistent with the outer circle of the non-threaded end of the angle injector head 2. There are two threaded positioning holes 1-4 and one positioning pin hole 1-3 on the inclined surface 1-1, and their position and size correspond one-to-one with the threaded holes and pin holes of the assembled angle injector 2.

[0028] Preferably, the angle error between the inclined surface of the fixture body 1 and the tilt angle of the angle injector 2 is ≤0.05°, which can ensure that the angle of the thread end after processing meets the requirements of the drawing.

[0029] Preferably, the end face of the fixture body 1 is provided with a positioning reference surface that fits with the stepped surface of the CNC lathe jaws, with a flatness of ≤0.01mm, which can achieve precise axial positioning and reduce clamping errors.

[0030] Preferably, the fixture body 1 is made of QT400-18 ductile iron and undergoes aging treatment, which combines high rigidity and vibration resistance, making it suitable for heavy cutting conditions.

[0031] Preferably, the fixture body 1 is provided with a modular interface, which allows for the replacement of adapter blocks with different eccentric hole diameters and bevel angles, thereby expanding the versatility of the fixture and adapting it to the processing of multiple types of fuel injector heads.

[0032] like Figure 8 As shown, the positioning pin 4 is a positioning component used to connect the clamp body 1 and the angle injector head 2, which can prevent misalignment between the body and the injector head.

[0033] Preferably, the locating pin 4 is made of hardened steel with a surface hardness ≥ HRC58 and a diameter tolerance of H7 grade, which can improve the wear resistance and positioning accuracy of the locating pin.

[0034] like Figure 9 As shown, the positioning hexagon socket bolt 3 is a fastening component that secures the fixture body 1 to the angle injector head 2. The strength and torque of the bolt must be guaranteed.

[0035] Preferably, the preload torque of the positioning hexagon socket bolt 3 is 20-25 N·m, and it is equipped with an anti-loosening washer to ensure stable clamping force and prevent loosening during processing.

[0036] This utility model embodiment also provides a machining method for an angled fuel injector head for a marine fuel system. Using the aforementioned special fixture, firstly, the outer circle of the non-threaded end of the angled fuel injector head 2 is inserted into the eccentric large hole of the body. Then, the positioning pin 4 on the inclined surface of the body 1 is inserted into the pin hole of the angled fuel injector head 2. Next, the plane of the angled fuel injector head 2 is aligned with the inclined surface of the body. At this point, the positioning hexagonal socket bolt 3 is tightened. The angle of the threaded end is now parallel to the outer circle, and the center of the threaded end is aligned with the center of the machine tool. The CNC lathe can be rotated to complete the machining of the entire threaded end according to the drawing. After disassembly, the angle of the threaded end meets the requirements of the drawing. Rapid positioning is achieved through the matching of the eccentric hole and the inclined surface angle, avoiding the problem of thread seizing caused by angle deviation.

[0037] Example 1, Manufacturing process of special fixture:

[0038] (1) After rough milling the fixture body 1, leave a 0.5mm allowance on the inclined surface;

[0039] (2) The eccentric hole and the inclined surface are finished by a five-axis machine tool in one clamping to ensure the angle tolerance is ±0.01°;

[0040] (3) The surface of the positioning pin 4 is nitrided to a depth of 0.2 mm;

[0041] Technical results: The fixture has a lifespan of over 5000 clamping cycles, and the wear of the locating pin is less than 0.005 mm.

[0042] Example 2, Machining steps for angle injector head:

[0043] (1) The eccentric hole of the cleaning fixture body 1 and the outer circle of the non-threaded end of the angle injector head 2.

[0044] (2) Insert the angle injector head 2 into the eccentric hole and rotate it until the positioning pin 4 falls into the pin hole.

[0045] (3) Tighten the positioning hexagon socket screws in diagonal order from 3 to 22 N·m, and check that the contact gap between the end face of the fixture body 1 and the lathe jaw is ≤0.02 mm.

[0046] (4) Call the CNC program to process the thread. Cutting parameters: speed 800r / min, feed 0.15mm / r.

[0047] Technical results: The processing time for a single piece has been reduced from 45 minutes to 20 minutes, and the thread coaxiality compliance rate has reached 100%.

[0048] The core utility model point of this utility model is:

[0049] 1. Eccentric hole-sloping surface cooperative positioning: The eccentric hole compensates for the tilt angle of the injector head, and the sloping surface fits together to achieve dual positioning.

[0050] 2. Double pin-bolt composite locking: The locating pin provides radial limit and the bolt provides axial clamping, ensuring clamping rigidity.

[0051] 3. Modular fixture design: Expand the machining range by changing the adapter block.

[0052] 4. Technical benefits: Clamping efficiency is increased by more than 50%, thread angle machining accuracy is ±0.05°, and it can be adapted to the machining of the entire range of MAN injector heads.

[0053] This is merely one embodiment of this application and does not cover all protection content. Simple modifications made based on the core structure of this application, such as using similar or related components to achieve the same processing, are all within the protection scope of this application.

Claims

1. A special fixture for machining angled fuel injector heads for marine fuel systems, characterized in that, The fixture includes a clamp body, locating pins, and locating hexagonal socket head cap screws. The locating surface of the clamp body is an inclined surface with an eccentric hole perpendicular to the bottom surface. The inner diameter of the eccentric hole is precisely fitted with the outer diameter of the non-threaded end of the angle injector head. The angle of the inclined surface of the clamp body is consistent with the tilt angle of the angle injector head. The inclined surface of the clamp body has at least two locating pin holes and threaded holes for locating and connecting the angle injector head. The locating pins are inserted between the angle injector head and the clamp body for radial limiting of the angle injector head. The locating hexagonal socket head cap screws pass through the mounting hole of the angle injector head and are tightly screwed into the threaded hole of the clamp body for axially pressing the angle injector head.

2. The special jig for machining the angled fuel injector head of a marine fuel system according to claim 1, characterized in that, The positions of the locating pin hole and the threaded hole match the corresponding hole positions of the angle injector head.

3. The special jig for machining the angled fuel injector head of a marine fuel system according to claim 1, characterized in that, The dimensions of the locating pin match the dimensions of the locating pin hole on the fixture body and the corresponding hole size of the angle injector head.

4. The special jig for machining the angle injector head of a marine fuel system according to claim 1, characterized in that, The rear end face of the fixture body is provided with a reference surface that fits with the stepped surface of the CNC lathe jaws, and the flatness is ≤0.01mm.

5. The special jig for machining the angled fuel injector head of a marine fuel system according to claim 1, characterized in that, The fixture body is made of QT400-18 ductile iron and has undergone aging treatment.

6. The special jig for machining the angle injector head of a marine fuel system according to claim 1, characterized in that, The fixture body is equipped with a modular interface, allowing for the replacement of adapter blocks with different eccentric hole diameters and bevel angles.

7. The special jig for machining the angle injector head of a marine fuel system according to claim 1, characterized in that, The locating pin has a surface hardness ≥ HRC58 and a diameter tolerance of H7 grade.

8. The special jig for machining the angle injector head of a marine fuel system according to claim 1, characterized in that, The preload torque of the positioning hexagon socket bolt is 20-25 N·m, and it is equipped with anti-loosening washers.

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