Special clamp and method for machining angle fuel injector head of marine fuel system

Abstract

The invention relates to a special clamp and method for machining an angle oil injector head of a marine fuel system, the positioning surface of a clamp body of the clamp is an inclined surface, an eccentric hole perpendicular to the bottom surface is formed, and the inner diameter of the eccentric hole can be precisely matched with the outer circle of the non-threaded end of the angle oil injector head; the slope angle of the clamp body is consistent with the inclination angle of the angle oil sprayer head. The inclined plane of the clamp body is provided with at least two positioning pin holes and threaded holes which are used for positioning and connecting the angle oil sprayer head, the positioning pin is inserted between the angle oil sprayer head and the clamp body, and the positioning inside hexagonal bolt penetrates through the angle oil sprayer head mounting hole and then is tightly screwed and fixed in the threaded hole of the clamp body. Compared with the prior art, the structure is simple, and installation is convenient; positioning is accurate, and reliability is high; stable processing can be realized; the angle machining device can be expanded to be suitable for angle machining of various same-type oil injector heads.

Description

Technical Field

[0001] The present invention relates to the manufacturing technology of fuel injection systems for marine high-power low-speed diesel engines, and specifically to a precision machining method and a special fixture for an angled injector head, which are applicable to the high-precision turning machining of the threaded end of the injector head of models such as MAN MEB / MEC. Background Art

[0002] With the extensive use of MAN's MEB and MEC models, it is particularly important to ensure the machining quality of components of fuel injection systems for marine high-power engines with high response and high reliability. This type of injector head is installed at an angle on the main engine. Due to the design of the main engine, the high-pressure oil pipe needs to be precisely connected to the angled thread of the injector head to achieve the transmission of high-pressure oil. Incorrect angles will cause problems such as inability to install and thread jamming caused by angle deviation. Therefore, it is necessary to ensure the machining of the thread angle. When machining, the method of deflecting the angle is used to adjust it to be consistent with the center of the CNC lathe, and the machining can be completed quickly and reliably. A special fixture needs to be designed to adjust the thread angle of the injector head to be at a zero-degree angle with the center of the CNC lathe.

[0003] For existing injector heads, due to the need for inclined installation, angle deviation at the threaded end easily leads to difficulties in installing the high-pressure oil pipe and thread jamming. The traditional method uses a general fixture in combination with angle shims for adjustment, which has problems such as cumbersome positioning and poor repeatability accuracy. For example, the patent document CN221210682U uses a telescopic joint for clamping, but the rigidity is insufficient; the bushing positioning structure in the patent document CN208803995U is complex and cannot meet the high-precision angle machining requirements of the injector head. Therefore, there is an urgent need for a special fixture and machining method that takes into account positioning accuracy, rigidity, and operational convenience. Summary of the Invention

[0004] The present invention provides a special fixture and method for machining an angled injector head of a marine fuel system. By using a specific fixture, the angled injector head is adjusted to be consistent with the rotation center of the machine tool, so as to achieve the purpose of machining.

[0005] To achieve the above object, the technical solution of the present invention is: a special fixture for machining an angled injector head of a marine fuel system, including a fixture body, a positioning pin, and an internal hexagonal bolt. The positioning surface of the fixture body is an inclined surface, and it is provided with an eccentric hole perpendicular to the bottom surface. The inner diameter of the eccentric hole can be precisely fitted with the outer circle of the non-threaded end of the angled injector head; the inclined surface angle of the fixture body is consistent with the inclined angle of the angled injector head; at least two positioning pin holes and threaded holes for positioning and connecting the angled injector head are provided on the inclined surface of the fixture body. The positioning pin is inserted between the angled injector head and the fixture body for radial limiting of the angled injector head; the positioning internal hexagonal bolt passes through the mounting hole of the angled injector head and is tightly screwed and fixed in the threaded hole of the fixture body for axially pressing the angled injector head.

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

[0007] Furthermore, the size of the positioning pin matches the sizes of the positioning pin holes of the fixture body and the corresponding holes of the angle injector head.

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

[0009] Furthermore, the material of the fixture body is QT400-18 ductile iron and is subjected to aging treatment.

[0010] Furthermore, the fixture body is provided with a modular interface, and adapter blocks with different eccentric hole diameters and inclined surface angles can be replaced.

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

[0012] Furthermore, the pre-tightening torque of the positioning hexagon socket head bolt is 20-25 N·m, and a lock washer is equipped.

[0013] A processing method for an angle injector head of a marine fuel system, using the described special fixture, includes the following steps:

[0014] a. Insert the non-threaded end of the angle injector head into the eccentric large hole of the fixture body;

[0015] b. Through the radial limit of the positioning pin, make the plane of the injector head fit the inclined surface of the fixture;

[0016] c. Tighten the positioning hexagon socket head bolts in a diagonal order to the preset torque;

[0017] d. After leveling, machine the threaded end by the CNC lathe.

[0018] Furthermore, in step c, the preset torque is 22 N·m, and the fitting clearance between the end face of the fixture body and the lathe chuck after clamping is ≤0.02 mm.

[0019] The beneficial effects of the present invention compared with the prior art include: 1) simple structure, convenient for installation; 2) accurate positioning; 3) high reliability; 4) stable processing can be achieved; 5) it can be extended and applied to the angle processing of various injectors of the same type. Description of the Drawings

[0020] Figure 1 It is a positioning fixture assembly drawing;

[0021] Figure 2 It is Figure 1 The sectional view along A-A in

[0022] Figure 3 For Figure 1 Cross-section along B-B and sectional view;

[0023] Figure 4 Schematic three-dimensional view of the body structure;

[0024] Figure 5 Front view of the body structure;

[0025] Figure 6 Left view of the body structure;

[0026] Figure 7 For Figure 5 Cross-section along B-B in

[0027] Figure 8 Schematic diagram of the positioning pin;

[0028] Figure 9 Schematic diagram of the hexagon socket head cap screw. Specific embodiments

[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0030] As Figures 1 to 9 shown, a special fixture for machining the angle fuel injector head of a marine fuel system provided by an embodiment of the present invention includes a fixture body 1, a positioning hexagon socket head cap screw 3, and a positioning pin 4.

[0031] 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 fuel injector head 2; the fixture body 1 is provided with an inclined surface 1-1, and the angle of the inclined surface is the same as the inclination angle of the angle fuel injector head 2; the fixture body 1 is provided with two threaded positioning holes 1-4 and a positioning pin hole 1-3, and the positions match the corresponding hole positions of the angle fuel injector head 2.

[0032] During use, the outer circular end face of the fixture body 1 abuts against the step surface of the chuck of the numerical control lathe 5 for positioning in the length direction. The eccentric large hole 1-2 on the inclined surface of the fixture body 1 is consistent with the outer circle of the non-threaded end of the angle fuel injector head 2, and the angle of the inclined surface 1-1 of the fixture body 1 is the same as the inclination angle of the angle fuel injector 2. The fixture body 1 is provided with two threaded positioning holes 1-4 and a positioning pin hole 1-3. The center distance of the positioning holes, the size and position of the positioning pin are all designed to be consistent with the corresponding holes of the angle fuel injector head 2 to ensure positioning and fastening during assembly.

[0033] As Figures 3 to 7As shown in the figure, the fixture body 1 has an eccentric large hole 1-2 that is off-center and 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 a positioning pin hole 1-3 on the inclined surface 1-1, and their position dimensions correspond one by one to the screw holes and pin holes of the assembled angle injector 2.

[0034] Preferably, the angle error between the inclined surface angle of the fixture body 1 and the inclined angle of the angle injector 2 is ≤0.05°, which can ensure that the angle of the threaded end meets the drawing requirements after machining.

[0035] Preferably, the end face of the fixture body 1 is provided with a positioning reference surface that fits the step surface of the CNC lathe chuck, and the flatness is ≤0.01mm, which can achieve accurate axial positioning and reduce the clamping error.

[0036] Preferably, the material of the fixture body 1 is QT400-18 ductile iron and is subjected to aging treatment, which has both high rigidity and vibration resistance and is suitable for heavy cutting conditions.

[0037] Preferably, the fixture body 1 is provided with a modular interface, and adapter blocks with different eccentric hole diameters and inclined surface angles can be replaced to expand the versatility of the fixture and adapt to the processing of multi-model injector heads.

[0038] As Figure 8 shown, the positioning pin 4, which is a positioning component for connecting the fixture body 1 and the angle injector head 2, can prevent the misalignment of the body and the injector head.

[0039] Preferably, the positioning pin 4 is made of hardened steel, the surface hardness is ≥HRC58, and the diameter tolerance is H7 level, which can improve the wear resistance and positioning accuracy of the positioning pin.

[0040] As Figure 9 shown, the positioning hexagon socket head bolt 3 is a fastening component that tightly connects the fixture body 1 and the angle injector head 2, and the strength and torque of the bolt need to be ensured.

[0041] Preferably, the pre-tightening torque of the positioning hexagon socket head bolt 3 is 20-25N·m, and a lock washer is equipped to ensure stable clamping force and prevent loosening during the machining process.

[0042] The embodiment of the present invention also provides a processing method for the angular injector head of a marine fuel system. Using the above-mentioned special fixture, first, the outer circle of the non-threaded end of the angular injector head 2 is inserted into the eccentric large hole of the body, and then the positioning pin 4 on the inclined surface of the body 1 is inserted into the pin hole of the angular injector head 2. Then, the plane of the angular injector head 2 is fitted to the inclined surface of the body. At this time, the positioning internal hexagonal bolt 3 is tightened. The angle of the threaded end is already parallel to the outer circle, and the center of the threaded end is consistent with the center of the machine tool. The numerical control lathe can rotate and 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. Through the matching of the eccentric hole and the inclined surface angle, rapid positioning is achieved, avoiding the problem of thread jamming caused by angle deviation.

[0043] Example 1, manufacturing process of the special fixture:

[0044] (1) After rough milling the fixture body 1, leave a 0.5 mm allowance at the inclined surface part;

[0045] (2) Use a five-axis machine tool to complete the finish machining of the eccentric hole and the inclined surface in one clamping, ensuring an angular tolerance of ±0.01°;

[0046] (3) Perform nitriding treatment on the surface of the positioning pin 4, with a layer depth of 0.2 mm;

[0047] Technical effect: The fixture life exceeds 5000 clamping times, and the wear of the positioning pin is <0.005 mm.

[0048] Example 2, processing steps of the angular injector head:

[0049] (1) Clean the eccentric hole of the fixture body 1 and the outer circle of the non-threaded end of the angular injector head 2.

[0050] (2) Insert the angular injector head 2 into the eccentric hole and rotate it until the positioning pin 4 falls into the pin hole.

[0051] (3) Tighten the positioning internal hexagonal screw 3 in a diagonal order to 22 N·m, and check that the fitting gap between the end face of the fixture body 1 and the lathe chuck is ≤0.02 mm.

[0052] (4) Call the numerical control program to machine the thread, with cutting parameters: rotational speed 800 r / min, feed 0.15 mm / r.

[0053] Technical effect: The single-piece processing time is shortened from 45 minutes to 20 minutes, and the compliance rate of the thread coaxiality reaches 100%.

[0054] The core inventive points of the present invention:

[0055] 1. Eccentric hole - inclined surface collaborative positioning: Compensate for the inclination angle of the injector head through the eccentric hole, and achieve double positioning in combination with the inclined surface fitting.

[0056] 2. Double-pin - bolt composite locking: The positioning pin provides radial limit, and the bolt provides axial compression to ensure clamping rigidity.

[0057] 3. Modular fixture design: The processing range can be extended by replacing the adapter block.

[0058] 4. Technical effects: The clamping efficiency is increased by more than 50%, the machining accuracy of the thread angle is ±0.05°, and it can be adapted to the processing of the entire MAN series of injector heads.

[0059] This is only one embodiment of this application and does not cover all the protected content. Simple deformations based on the core structure of this application, such as the form of using similar related components to achieve the same processing, etc. are all within the protection scope of this application.

Claims

1. A special fixture for processing angle injector heads of marine fuel systems, characterized in that: It includes a fixture body, a locating pin, and a hexagon socket bolt. The locating surface of the fixture body is an inclined surface, and is provided with an eccentric hole perpendicular to the bottom surface. The inner diameter of the eccentric hole is precisely matched with the outer circle of the non-threaded end of the angle injector head; the angle of the inclined surface of the fixture body is consistent with the inclination angle of the angle injector head; at least two locating pin holes and threaded holes for positioning and connecting the angle injector head are provided on the inclined surface of the fixture body, and the locating pin is inserted between the angle injector head and the fixture body for radial limitation of the angle injector head; the positioning hexagon socket bolt passes through the mounting hole of the angle injector head and is tightly screwed and fixed in the threaded hole of the fixture body for axially compressing the angle injector head.

2. The special fixture for machining angle injector heads of marine fuel systems according to claim 1 is 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 fixture for machining angle injector head of marine fuel system according to claim 1 is characterized in that: The size of the locating pin matches the size of the locating pin hole of the fixture body and the corresponding hole of the angle injector head.

4. The special fixture for machining angle injector heads of marine fuel systems according to claim 1 is characterized in that: The rear end surface of the clamp body is provided with a reference surface which fits with the step surface of the CNC lathe jaws, and the flatness is ≤0.01mm.

5. The special fixture for machining angle injector head of marine fuel system according to claim 1 is characterized in that: The material of the clamp body is QT400-18 ductile iron and has been subjected to aging treatment.

6. The special fixture for machining angle injector heads of marine fuel systems according to claim 1, characterized in that: The clamp body is provided with a modular interface, and adapter blocks with different eccentric apertures and bevel angles can be replaced.

7. The special fixture for machining angle injector heads of marine fuel systems according to claim 1, characterized in that: The surface hardness of the positioning pin is ≥HRC58, and the diameter tolerance is H7.

8. The special fixture for machining angle injector heads of marine fuel systems according to claim 1 is characterized in that: The pre-tightening torque of the positioning hexagon socket bolt is 20-25 N·m, and an anti-loosening gasket is provided.

9. A method for processing an angle injector head for a marine fuel system, characterized in that: The special fixture according to any one of claims 1 to 8 is used, comprising the following steps: a. Insert the non-threaded end of the angle injector head into the eccentric large hole of the fixture body; b. Use the positioning pin to limit the radial position so that the plane of the angle injector head fits with the inclined surface of the fixture; c. Tighten the hexagon socket bolts in diagonal order to the preset torque; d. After leveling, the threaded end is processed by CNC lathe.

10. The method according to claim 9, characterized in that The preset torque in step c is 22 N·m, and after clamping, the fitting clearance between the end face of the fixture body and the lathe jaws is ≤0.02 mm.

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