Machining method for pressure storage element of diesel engine

Abstract

The invention relates to a machining method for a pressure storage element of a diesel engine, which comprises the following steps: S1, deep hole machining: adopting a deep hole drilling process, and completing deep hole machining through one-time clamping; s2, outer circle machining, wherein orifices in the two ends of the oil storage cavity are used for positioning, and outer circle finish turning is conducted; s3, thread machining is conducted, specifically, the outer circle obtained after finish turning is used for positioning, and threads at the two ends are milled; s4, positioning machining is conducted, specifically, a positioning flat position on the pressure storage element body is milled; s5, milling a joint seat surface: milling a mounting seat surface of a high-pressure oil outlet joint on the pressure storage element body; s6, welding machining is conducted, specifically, a friction welding technology is adopted, and a plurality of high-pressure oil outlet connectors are evenly welded; s7, stepped hole machining, wherein a stepped hole is drilled; milling a sealing conical surface of the pressure storage element body; milling an external thread of the oil outlet joint; and S8, burr removal, wherein burrs are removed through a liquid extrusion grinding process. The problems existing in machining of the pressure storage element in the prior art are solved, and the method can be applied to the manufacturing and machining process of the pressure storage element of the diesel engine.

Description

Technical Field

[0001] This application relates to the field of accumulator manufacturing technology, and in particular to a method for manufacturing an accumulator for a diesel engine. Background Technology

[0002] A diesel engine's high-pressure common rail fuel system has a fuel pressure of 220 MPa. To ensure stable system injection pressure, a high-precision accumulator element is required. Commercially available accumulator elements employ an integral structure, using the largest outer diameter bar stock for machining. While this structure offers high strength, it consumes a lot of raw materials and requires significant machining removal, resulting in high manufacturing costs and low production efficiency, which is unfavorable for mass production needs.

[0003] Meanwhile, the manufacturing of the accumulator element required for a certain diesel engine presents the following challenges: First, it is difficult to guarantee the machining accuracy of the deep holes in the oil reservoir with a large length-to-diameter ratio. Poor machining accuracy of the straightness of the oil reservoir results in uneven wall thickness of the accumulator element, reducing its overall strength. Second, it is difficult to remove burrs from the walls of the oil reservoir holes and the intersecting holes. After drilling, microscopic burrs remain on the hole walls, and burrs at the intersections of the high-pressure oil outlet and the oil reservoir also have flanged burrs. Since the oil passage holes at the intersections are Φ1.5 small holes, these burrs are difficult to remove, easily causing blockage of the injector throttle orifice and jamming of moving parts, affecting the overall engine performance. Third, it presents the challenge of precise welding of the high-pressure oil outlet connector. The accumulator element has eight high-pressure oil outlet connectors welded evenly. These connectors connect the high-pressure oil pipe to the accumulator element. To ensure the high-pressure sealing requirements of the oil pipe and the sealing cone surface, the positional accuracy of the connector thread and the cone surface of the oil outlet is extremely strict.

[0004] In view of this, the present application aims to develop a method for processing a voltage accumulator to overcome the above-mentioned technical problems. Summary of the Invention

[0005] The technical problem to be solved by this application is that the existing processing technology for accumulators consumes a lot of raw materials, has a large amount of material removed during processing, has high manufacturing costs, low production efficiency, and is not conducive to mass production. At the same time, for the accumulator required for a certain diesel engine, there are problems such as difficulty in ensuring the machining accuracy of the deep holes of the oil storage cavity with a large length-to-diameter ratio, and difficulty in removing burrs from the walls of the oil storage cavity and the intersecting holes of the accumulator.

[0006] To solve the above-mentioned technical problems, this application provides a method for processing a pressure accumulator element for a diesel engine, comprising the following steps:

[0007] S1: Deep hole machining: The accumulator body to be machined is machined using deep hole drilling technology, and the deep hole machining is completed in one clamping to form a deep hole for oil storage cavity;

[0008] S2: Outer circle machining: Using the openings at both ends of the oil storage cavity for positioning, precision machine the outer circle;

[0009] S3: Thread machining: Using the precision-turned outer circle as a positioning point, mill the threads at both ends;

[0010] S4: Positioning machining: Milling the positioning flat part on the body of the accumulator element;

[0011] S5: Milling the mounting surface of the connector: Leave welding allowance and welding operation space, and mill several mounting surfaces of high-pressure oil outlet connectors on the body of the accumulator element.

[0012] S6: Welding process: Several high-pressure oil outlet joints are uniformly welded onto the milled seat surface using friction welding technology;

[0013] S7: Stepped hole machining: Drilling stepped holes to connect the oil reservoir and the oil outlet connector; milling the sealing cone surface of the accumulator body; milling the external thread of the oil outlet connector;

[0014] S8: Burr Removal: Using liquid extrusion grinding process, micro-burrs on the hole wall after drilling are removed, as well as burrs at the intersection of high-pressure oil outlet / oil storage channels.

[0015] According to an embodiment of this application, the processing parameters for step S1 are: a deep hole length-to-diameter ratio of 180:1, a deep hole straightness of ≤0.05mm, and a coaxiality of ≤0.05mm.

[0016] According to the embodiments of this application, the deep hole drilling process in step S1 adopts a graded feed strategy: in the initial stage, the feed is 50% of the normal speed, and after the drill bit enters a stable state, it is gradually increased to the normal speed; when the drilling depth reaches 100 times the diameter, the feed speed is reduced again to prevent the drill bit from fatigue fracture.

[0017] According to an embodiment of this application, in step S2, the coaxiality between the outer circle and the deep hole is ≤0.05mm.

[0018] According to an embodiment of this application, in step S2, a precision centering fixture is used to achieve precise centering through an expansion sleeve or elastic chuck. During the turning process, constant linear speed cutting is used, and the spindle speed is automatically adjusted according to the outer diameter to ensure the consistency of surface roughness.

[0019] According to an embodiment of this application, in step S3, the thread machining adopts CNC thread milling process, and high-precision thread machining is achieved through multi-axis linkage. The tool selected is a carbide thread milling cutter, and the cutting parameters are: rotation speed 1500-2000rpm, feed rate 0.5-1mm / r.

[0020] According to an embodiment of this application, the accumulator body is a round bar with a length of 1800 mm, and the accumulator body is made of 42CrMo material with a tempered hardness of 32-36 HRC.

[0021] According to an embodiment of this application, the high-pressure oil outlet connector is made of high-strength alloy steel.

[0022] According to an embodiment of this application, in step S6, during the friction welding process, the welding parameters are strictly controlled: friction pressure 150-200MPa, friction time 10-15 seconds, upsetting pressure 300-400MPa, and upsetting time 3-5 seconds.

[0023] According to an embodiment of this application, in step S7, the sealing cone surface is machined using a one-time clamping process, and the coaxiality of the sealing cone surface axis and the thread axis is controlled within 0.05mm by a CNC machining center.

[0024] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0025] 1. This application adopts deep hole machining technology with a large length-to-diameter ratio. By using special deep hole drilling equipment, optimizing process parameters, and implementing online monitoring, the machining accuracy under the extreme length-to-diameter ratio of 180:1 can be effectively controlled to meet the usage requirements of the accumulator element. At the same time, an oil outlet connector is welded on the surface of the accumulator element to minimize the consumption of raw materials and reduce the manufacturing cost and time cost caused by removing large allowances.

[0026] 2. Regarding the burr removal technology for cross holes, this application adopts liquid extrusion grinding technology. Through the extrusion and flow cutting of flexible abrasive media, burrs in the Φ1.5mm micro cross holes can be completely removed, and the surface roughness is reduced from Ra3.2μm to below 0.8μm, effectively solving the problem of dead corners that are difficult to reach by traditional methods.

[0027] 3. Regarding the precision welding technology for high-pressure oil outlet joints, this application adopts friction welding process. By precisely controlling the welding parameters, uniform welding of the joint is achieved, and the sealing performance meets the requirements of the high-pressure environment, thus ensuring the reliability of the high-pressure common rail system.

[0028] 4. In terms of manufacturing process integration technology, this application adopts a process route of "one-time clamping and multi-process integration", which facilitates the mass production of accumulator components. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this application, and are not intended to limit this application.

[0030] Figure 1 This is a flowchart illustrating a method for processing a pressure accumulator element for a diesel engine, as an example of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the described embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains. The terms “first,” “second,” and similar terms used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a,” and similar terms, do not indicate a limitation of quantity, but rather indicate the presence of at least one.

[0033] like Figure 1 As shown in the example of this invention, a method for processing a pressure accumulator element for a diesel engine is described. This method adopts a "one-time clamping, multi-process integration" process route. By optimizing the process arrangement and unifying the benchmark, it minimizes cumulative errors and improves manufacturing accuracy. The overall process flow includes: drilling deep holes—precision turning of the outer diameter—milling threads at both ends—milling the positioning flat—milling the seat surface—welding the joint—drilling holes—milling threads—milling the sealing cone surface of the body—abrasive extrusion cross holes. The method involves drilling deep holes in one clamping setup, turning the outer diameter with the hole opening as the positioning point, achieving a coaxiality ≤0.05mm, overcoming the problems of straightness and uneven wall thickness in deep holes with large length-to-diameter ratios; liquid extrusion grinding, fully covering and removing micro-burrs and flange burrs; reserving welding allowance, friction welding to reduce deformation, and ensuring coaxiality ≤0.05mm in one clamping setup, overcoming the problems of joint welding position accuracy and sealing coaxiality.

[0034] In this embodiment, a method for processing a pressure accumulator element for a diesel engine includes the following steps:

[0035] S1: Deep Hole Machining: The accumulator body to be machined is machined using a deep hole drilling process, completing the deep hole machining in one clamping operation to form the deep hole for the oil storage cavity. This step avoids deviations in the straightness of the channel caused by multiple clamping operations, prevents uneven wall thickness of the accumulator, ensures overall strength, provides a reference for subsequent outer diameter machining, and ensures the coaxiality of the deep hole and the outer diameter.

[0036] Specifically, in step S1, the deep hole drilling process adopts a staged feed strategy: initially, the feed is 50% of the normal speed, and after the drill bit enters a stable state, it is gradually increased to the normal speed; when the drilling depth reaches 100 times the diameter, the feed speed is reduced again to prevent the drill bit from fatigue fracture.

[0037] Specifically, the machining parameters for step S1 are a deep hole length-to-diameter ratio of 180:1, a deep hole straightness ≤0.05mm, and a coaxiality ≤0.05mm. For deep hole machining with the 180:1 limiting length-to-diameter ratio, a specialized deep hole drilling technology is employed. The core of this technology lies in using a specialized deep hole drill bit with a single-edge external chip removal structure. Through precise guidance and cooling system design, the ultra-long deep hole can be machined in one pass. Regarding tool selection, for deep holes with a diameter less than 10mm, a gun drill is preferred; for diameters between 10-30mm, a BTA internal chip removal drill bit is used; and for diameters greater than 30mm, a jet-suction external chip removal drill bit is used.

[0038] S2: External Diameter Machining: Using the openings at both ends of the oil reservoir for positioning, precision machine the external diameter. This step provides a high-precision external diameter datum for subsequent thread, flat section, and seat surface machining, unifying the positioning datum for each process and reducing cumulative errors.

[0039] Specifically, in step S2, the coaxiality between the outer circle and the deep hole is ≤0.05mm.

[0040] Specifically, in step S2, the outer diameter is precision-centered using a precision centering fixture, which achieves precise centering through a chuck or elastic collet. During the turning process, constant linear speed cutting is used, and the spindle speed is automatically adjusted according to the outer diameter to ensure the consistency of surface roughness.

[0041] S3: Thread machining: Using the precision-machined outer circle as a positioning point, mill the threads at both ends. This step is to ensure the perpendicularity of the sealing plane to the thread axis, so as to meet the sealing requirements of subsequent assembly.

[0042] Specifically, in step S3, the thread machining can be carried out using CNC thread milling technology, which achieves high-precision thread machining through multi-axis linkage. The tool selected is a carbide thread milling cutter, and the cutting parameters are: speed 1500-2000 rpm, feed rate 0.5-1 mm / r.

[0043] S4: Positioning Machining: Milling the positioning flat part on the accumulator body. This step serves as a dedicated positioning reference for the subsequent machining of the oil outlet of the body, ensuring that the position of the oil outlet corresponds precisely to the oil storage cavity.

[0044] S5: Milling the mounting surface of the connector: Leave welding allowance and welding operation space, and mill several mounting surfaces of the high-pressure oil outlet connectors on the body of the accumulator element. This step provides a flat and precise bearing surface for subsequent welding of the high-pressure oil outlet connectors, and avoids positional deviation caused by uneven contact surfaces during welding.

[0045] S6: Welding Process: Friction welding is used to uniformly weld several high-pressure oil outlet joints onto the milled seat surface. Friction welding has a small heat-affected zone and minimal welding deformation, preventing the threads and conical surface from shifting after welding. This process ensures the positional accuracy of the joint thread axis and the conical surface of the oil outlet hole, meeting the sealing requirements of high-pressure oil pipe connections (the sealing conical surface must withstand high-pressure sealing).

[0046] Specifically, in step S6, the friction welding process strictly controls the welding parameters: friction pressure 150-200 MPa, friction time 10-15 seconds, upsetting pressure 300-400 MPa, and upsetting time 3-5 seconds. The core advantage of friction welding technology lies in its low heat input characteristics. Compared with traditional fusion welding methods, the welding temperature of friction welding is controlled within the forging temperature range of the material, avoiding thermal deformation and microstructural deterioration caused by high-temperature melting. In the application of accumulator components, friction welding can effectively ensure the positional accuracy and dimensional stability of the joint. By precisely controlling the friction parameters (rotation speed, friction time, friction pressure) and upsetting parameters (upsetting force, upsetting time), uniform heating of the contact surface is ensured, avoiding incomplete penetration or excessive plastic deformation. Simultaneously, cooling control eliminates stress through slow cooling or heat treatment, preventing joint embrittlement.

[0047] S7: Stepped hole machining: Drill stepped holes to connect the oil storage chamber and the oil outlet connector; mill the sealing cone surface of the accumulator body; mill the external thread of the oil outlet connector.

[0048] Specifically, in this application, all the above-mentioned processes are completed in one clamping, ensuring that the coaxiality between the sealing cone axis and the thread axis is ≤0.05mm, which meets the high-pressure sealing requirements of the high-pressure oil pipe and the sealing cone, and avoids the risk of oil leakage due to coaxiality deviation.

[0049] Specifically, in step S7, the sealing cone surface is machined using a one-time clamping process. The coaxiality between the axis of the sealing cone surface and the thread axis is controlled within 0.05mm by a CNC machining center. The sealing cone surface is designed on the body, ensuring the sealing effect and sealing strength.

[0050] S8: Burr Removal: Using liquid extrusion grinding process, micro-burrs on the hole wall after drilling are removed, as well as burrs at the intersection of high-pressure oil outlet / oil storage channels.

[0051] Specifically, the accumulator body is a round bar with a length of 1800mm, and the accumulator body is made of 42CrMo material with a tempered hardness of 32-36HRC.

[0052] Specifically, for the intersection of the oil reservoir and the high-pressure oil outlet, and the hole wall (especially for the intersection of Φ1.5mm small holes), a liquid extrusion grinding (abrasive extrusion) process is used to remove the micro-burrs on the hole wall after drilling, as well as the burrs on the edge of the intersection of the high-pressure oil outlet / oil reservoir; to prevent burrs from falling off and causing blockage of the injector throttle hole or jamming of moving parts, thus ensuring the overall performance of the engine.

[0053] Specifically, the high-pressure oil outlet connector can be made of high-strength alloy steel.

[0054] In summary, the technical solution of this application has the following beneficial effects:

[0055] 1. This application adopts deep hole machining technology with a large length-to-diameter ratio. By using special deep hole drilling equipment, optimizing process parameters, and implementing online monitoring, the machining accuracy under the extreme length-to-diameter ratio of 180:1 can be effectively controlled to meet the usage requirements of the accumulator element. At the same time, an oil outlet connector is welded on the surface of the accumulator element to minimize the consumption of raw materials and reduce the manufacturing cost and time cost caused by removing large allowances.

[0056] 2. Regarding the burr removal technology for cross holes, this application adopts liquid extrusion grinding technology. Through the extrusion and flow cutting of flexible abrasive media, burrs in the Φ1.5mm micro cross holes can be completely removed, and the surface roughness is reduced from Ra3.2μm to below 0.8μm, effectively solving the problem of dead corners that are difficult to reach by traditional methods.

[0057] 3. Regarding the precision welding technology for high-pressure oil outlet joints, this application adopts friction welding process. By precisely controlling the welding parameters, uniform welding of the joint is achieved, and the sealing performance meets the requirements of the high-pressure environment, thus ensuring the reliability of the high-pressure common rail system.

[0058] 4. In terms of manufacturing process integration technology, this application adopts a process route of "one-time clamping and multi-process integration", which facilitates the mass production of accumulator components.

[0059] The above are merely exemplary embodiments of this application and are not intended to limit the scope of protection of this application, which is determined by the appended claims.

Claims

1. A method for processing a pressure accumulator element for a diesel engine, characterized in that, Includes the following steps: S1: Deep hole machining: The accumulator body to be machined is machined using deep hole drilling technology, and the deep hole machining is completed in one clamping to form a deep hole for oil storage cavity; S2: Outer circle machining: Using the openings at both ends of the oil storage cavity for positioning, precision machine the outer circle; S3: Thread machining: Using the precision-turned outer circle as a positioning point, mill the threads at both ends; S4: Positioning machining: Milling the positioning flat part on the body of the accumulator element; S5: Milling the mounting surface of the connector: Leave welding allowance and welding operation space, and mill several mounting surfaces of high-pressure oil outlet connectors on the body of the accumulator element. S6: Welding process: Several high-pressure oil outlet joints are uniformly welded onto the milled seat surface using friction welding technology; S7: Stepped hole machining: Drilling stepped holes to connect the oil reservoir and the oil outlet connector; milling the sealing cone surface of the accumulator body; milling the external thread of the oil outlet connector; S8: Burr Removal: Using liquid extrusion grinding process, micro-burrs on the hole wall after drilling are removed, as well as burrs at the intersection of high-pressure oil outlet / oil storage channels.

2. The method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, The processing parameters for step S1 are: a deep hole length-to-diameter ratio of 180:1, a deep hole straightness of ≤0.05mm, and a coaxiality of ≤0.05mm.

3. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, In step S1, the deep hole drilling process adopts a staged feed strategy: initially, the feed is 50% of the normal speed, and after the drill bit enters a stable state, it is gradually increased to the normal speed; when the drilling depth reaches 100 times the diameter, the feed speed is reduced again to prevent the drill bit from fatigue fracture.

4. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, In step S2, the coaxiality between the outer circle and the deep hole is ≤0.05mm.

5. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, In step S2, a precision centering fixture is used to achieve precise centering through an expansion sleeve or elastic chuck. During the turning process, constant linear speed cutting is used, and the spindle speed is automatically adjusted according to the outer diameter to ensure the consistency of surface roughness.

6. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, In step S3, the thread machining adopts CNC thread milling process, which achieves high-precision thread machining through multi-axis linkage. The tool selected is a carbide thread milling cutter, and the cutting parameters are: speed 1500-2000rpm, feed rate 0.5-1mm / r.

7. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, The accumulator body is a round bar with a length of 1800mm, and the accumulator body is made of 42CrMo material with a tempered hardness of 32-36HRC.

8. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, The high-pressure oil outlet connector is made of high-strength alloy steel.

9. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, In step S6, the friction welding process strictly controls the welding parameters: friction pressure 150-200MPa, friction time 10-15 seconds, upsetting pressure 300-400MPa, and upsetting time 3-5 seconds.

10. A method for processing a pressure accumulator element for a diesel engine according to claim 1, characterized in that, In step S7, the sealing cone surface is machined using a single clamping process, and the coaxiality of the sealing cone surface axis and the thread axis is controlled within 0.05mm by a CNC machining center.

Images