A large ship exhaust gas manifold gap special adjusting tool and adjusting method thereof

Abstract

The application discloses a special adjusting tool for a large ship scavenging manifold gap and a method thereof. The tool comprises a tool body in a "Fang" open structure, and an adjusting bolt tool body is arranged in a threaded guide hole. An upper supporting arm of the tool body is used as a counterforce supporting base, and a lower supporting arm inner side reference fitting surface is fitted to a frame plane as a fixed reference surface. A fine tooth screw pair is adopted between the adjusting bolt and the threaded guide hole, accurate axial feeding is generated during rotation, and the abutting end head pushes the scavenging manifold flange downward, so that the gap is precisely and finely adjusted. The adjusting method adopts multiple sets of tools which are arranged along the flange circumference and are finely adjusted in turn according to a symmetrical cross sequence. The scavenging manifold and the frame plane gap can be accurately controlled within 0.10mm-0.15mm, the oil and gas leakage problem is effectively solved, and the adjusting efficiency and safety are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of marine low-speed diesel engine manufacturing technology, and in particular to a special adjustment tool for the clearance of the scavenging manifold of large ships and its adjustment method. Background Technology

[0002] The scavenging manifold is a crucial component of large, low-speed marine diesel engines. During the final assembly of these engines, the scavenging manifold needs to be connected to the engine frame. Due to its complex shape, large size, heavy weight, poor rigidity, and susceptibility to deformation, gaps can easily form at the connection surface between the scavenging manifold and the engine frame during assembly. If these gaps exceed the allowable range, they can lead to oil and air leaks during engine operation, affecting not only the engine's normal performance but also potentially shortening its overall service life.

[0003] Currently, there is a lack of specialized tools for adjusting the gap between the scavenging manifold and the frame plane during the scavenging manifold assembly operation. Operators typically rely on experience and conventional methods to adjust the gap, which is difficult to control precisely, resulting in low efficiency and an inability to guarantee the consistency and reliability of the gap dimensions. Existing technologies include tooling for positioning and adjusting the scavenging manifold and the inlet flange, but there is still no specialized tooling for quickly and accurately adjusting the gap between the scavenging manifold and the frame plane after assembly.

[0004] Therefore, it is necessary to design a new type of special adjustment tool for the clearance of scavenging manifolds of large ships, which can quickly and accurately adjust the clearance between the scavenging manifold and the frame plane to the specified range during the scavenging manifold closing process, thereby improving work efficiency, ensuring installation quality, and eliminating potential safety and quality hazards. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of adjusting the clearance between the scavenging manifold and the frame plane in existing technologies, and to provide a tool for quickly adjusting the clearance between the scavenging manifold and the frame plane. Using this invention, the clearance between the scavenging manifold and the frame plane can be adjusted to between 0.10mm and 0.15mm in a relatively short time, greatly improving work efficiency and safety reliability.

[0006] The technical solution of the present invention: A special adjustment tooling for the clearance of scavenging manifolds in large ships is disclosed. The tooling mainly consists of two parts: the tooling body and the adjusting bolts. The two parts work together to form a complete spiral pressurization-reaction support precision fine-tuning system.

[0007] The main body of the tooling has an overall "U"-shaped (or "C"-shaped) open structure, including an upper support arm, a lower support arm, and a vertical connecting arm fixedly connected between the upper and lower support arms. An open bayonet is formed between the upper and lower support arms, which is used for laterally mounting across the outer edge of the scavenging manifold flange. The upper support arm has a threaded guide hole that penetrates vertically along its thickness direction, and the inner wall of the threaded guide hole has internal threads. The inner surface of the lower support arm is a precision-machined reference contact surface (its flatness is preferably no greater than 0.02mm), used to tightly fit against the frame plane during tooling mounting, serving as a fixed reference surface throughout the clearance adjustment process.

[0008] The adjusting bolt passes through the threaded guide hole, and its shank has an external thread. The external thread and the internal thread of the threaded guide hole form a helical transmission pair. The front end of the adjusting bolt has an abutment end (preferably a spherical or planar structure) for directly pressing against the upper surface of the scavenging manifold flange; the rear end of the adjusting bolt has a force-applying head (preferably a standard external hexagonal head or internal hexagonal interface) for using a torque wrench or a regular wrench to apply rotational force.

[0009] Furthermore, the threaded pair between the adjusting bolt and the threaded guide hole adopts a fine-pitch thread pair (the pitch is preferably 1.5mm or 2.0mm). Based on this fine-pitch thread pair, the upper support arm acts as a reaction support seat. When the adjusting bolt rotates, it generates a precise and minute axial feed displacement relative to the tooling body. The abutting end at its front end applies a downward pushing force to the scavenging manifold flange. Under the combined action of the fixed reference reaction force provided by the lower support arm, the scavenging manifold flange is quantitatively pushed towards the frame plane, thereby realizing the precise fine adjustment of the gap between the scavenging manifold and the frame plane.

[0010] As a preferred material option, the main body of the tooling is made of 45 steel, and the adjusting bolt is made of 40CrNiMo high-strength alloy structural steel. The combination of the two ensures the overall rigidity and durability of the tooling, as well as the ability of the threaded pair to maintain accuracy and resist impact fatigue under heavy load conditions.

[0011] As a preferred manufacturing process, the upper support arm, lower support arm, and vertical connecting arm of the tooling body can be formed by integral forging, or by welding the components separately and then annealing them to relieve stress to form an integral structure.

[0012] Based on the above-mentioned tooling structure, the present invention also provides a construction method for adjusting the clearance of the scavenging manifold using this special adjustment tooling, the method comprising the following specific steps: Step 1: Circumferential arrangement and installation of multiple sets of tooling Based on the diameter of the scavenging manifold flange, multiple sets (usually 4 to 6 sets) of the aforementioned tooling are evenly spaced along the circumference of the scavenging manifold flange. The main body of each tooling is laterally mounted from the side across the mating area between the scavenging manifold flange and the frame plane using its open bayonet, ensuring that the inner reference contact surface of the lower support arm of each tooling is tightly fitted to the frame plane, and that the abutting end of the adjusting bolt of each tooling is aligned with the corresponding stress point on the upper surface of the scavenging manifold flange.

[0013] Step 2: Initial gap multi-point measurement and adjustment calculation Using feeler gauges and other testing tools, the actual clearance between the lower plane of the current scavenging manifold flange and the frame plane at each arrangement point was measured, and the initial clearance data at each point was recorded in detail. Based on the difference between the measured clearance value and the preset target clearance value (target range 0.10mm~0.15mm) at each point, the required adjustment displacement at each point was determined. On this basis, according to the required adjustment displacement at each point and the thread pitch of the corresponding adjusting bolt, the theoretical angle value required for the rotation of each tooling adjusting bolt was calculated according to the formula θ = (ΔH / P)× 360° (where ΔH is the difference between the measured clearance and the target clearance, and P is the thread pitch of the adjusting bolt).

[0014] Step 3: Quantitative rotary feed and axial push Rotate the adjusting bolts of each tooling one by one, causing each adjusting bolt to undergo axial displacement relative to the corresponding tooling body. During the rotation, the abutting end of each adjusting bolt pushes downwards to quantitatively push the upper surface of the scavenging manifold flange. Under the fixed reference reaction force provided by the lower support arm of each tooling, the gap between the lower plane of the scavenging manifold flange and the frame plane at each point is gradually reduced.

[0015] Step 4: Dynamic fine-tuning and precision locking of symmetrical cross-wheel sequence During the rotation of each adjusting bolt, feeler gauges are used to monitor the changes in clearance values ​​at each point in real time. Specifically, operators must perform multiple rounds of fine-tuning of the adjusting bolts on each fixture in a symmetrical, alternating sequence (e.g., adjusting positions 1, 3, and 5 first, then positions 2, 4, and 6, and so on). Large adjustments on one side at a time are strictly prohibited to prevent flange warping or stress concentration. After each round of adjustment, the clearance at all measuring points must be re-measured, using a progressively closer approach until the clearance values ​​at all points are consistently within the target range of 0.10mm to 0.15mm.

[0016] Step 5: Tightening and Fixture Removal After all the gaps at the inspection points have been adjusted to be within acceptable limits, keep the adjusting bolts of each tooling in a slightly pre-tightened state and use each tooling to temporarily assist in positioning the scavenging manifold. Then, complete the final tightening of the bolts connecting the scavenging manifold to the engine frame according to the diesel engine assembly process specifications. After all the connecting bolts have reached the specified torque, rotate the adjusting bolts of each tooling in the reverse direction to completely release the jacking force on the scavenging manifold flange, and then pull out and remove the main body of each tooling laterally.

[0017] Compared with the prior art, the technical effects of the present invention are as follows: 1) The screw drive structure of "C-shaped body + high-strength bolts" is used, especially the introduction of fine-pitch thread pairs into the heavy-load jacking scenario of scavenging manifolds on large ships. By utilizing the small lead characteristics of fine-pitch threads (pitch 1.5mm or 2.0mm), the rotational motion of the bolt is converted into extremely high-resolution linear displacement, achieving axial feed control accuracy of 0.01mm. This ensures that the gap between the scavenging manifold and the frame plane is stably and uniformly controlled within a strict tolerance range of 0.10mm to 0.15mm, fundamentally solving the industry problem of oil and air leakage in the scavenging manifold and shortened diesel engine service life caused by excessive gap tolerance in existing technologies.

[0018] 2) In this invention, the upper support arm of the tooling body serves as a reaction support seat to bear the counter torque of the bolt rotation feed, while the lower support arm serves as a fixed reference surface that fits against the frame plane and bears the jacking reaction force. The two work together to form a closed force flow loop, ensuring that the jacking force acts entirely on the scavenging manifold flange without any component force loss or off-center load, which greatly improves the stability and safety of the adjustment process and fundamentally avoids equipment damage or personnel safety accidents that may be caused by knocking or prying.

[0019] 3) For the assembly characteristics of large flange components, an operation process of "multiple sets of tooling evenly distributed around the circumference + symmetrical cross-sequence fine-tuning" is proposed. This process effectively avoids the warping and stress concentration problems of large flanges caused by single-point or unilateral adjustments, ensuring uniformity of the gap across the entire flange circumference. It represents a significant improvement in the precision assembly technology of large thin-walled rigid structural components. Those skilled in the art would not easily conceive of this targeted process step in conventional fixture operations, demonstrating its outstanding substantive characteristics.

[0020] 4) The tooling has a simple structure and is easy to assemble and disassemble. Operators can quickly and accurately adjust the tooling by simply rotating the thread and checking with a feeler gauge. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the special adjustment tool for the clearance of the scavenging manifold of large ships according to the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention. These are merely preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made to the content of the claims of this invention should be within the technical scope of this invention.

[0023] like Figure 1 As shown, a special tooling for adjusting the gap between the scavenging manifold and the frame plane during the closure process of the scavenging manifold of a large ship consists of a tooling body 1 and adjusting bolts 2.

[0024] In this embodiment, the main body of the tooling 1 is made of 45# steel, integrally forged, and then precision-manufactured by milling, drilling, and other machining methods. The main body of the tooling 1 is constructed in a "C"-shaped (i.e., C-shaped) opening structure, specifically including an upper support arm, a lower support arm, and a vertical connecting arm vertically connected to the same end of the two. The vertical spacing between the upper and lower support arms forms an open bayonet, the opening width of which must be greater than the total thickness of the edge of the scavenging manifold flange to be adjusted and the edge of the frame, so as to facilitate the horizontal insertion of the tooling from the side. To ensure stable force, the upper surface (i.e., the inner plane) of the lower support arm is precision ground to ensure that its flatness is no greater than 0.02mm, serving as a fixed reference contact surface during adjustment, for tightly abutting against the frame plane. A threaded guide hole is provided in the center of the upper support arm, penetrating vertically along its thickness direction, and a high-precision internal thread is machined in the threaded guide hole by tapping.

[0025] In this embodiment, the adjusting bolt 2 is made of 40CrNiMo high-strength alloy structural steel. After quenching and tempering, the yield strength of 40CrNiMo steel can reach over 800MPa, and it has excellent impact toughness and fatigue resistance, capable of repeatedly withstanding the huge thrust from the weight of the scavenging manifold without plastic deformation or thread damage. The adjusting bolt 2 is a fully threaded screw structure with external threads machined on its shank. In particular, to achieve high-precision gap control of 0.10mm to 0.15mm, the adjusting bolt 2 preferably uses fine-pitch threads, such as nominal diameters of M24×1.5 or M30×2.0. Taking M24×1.5 as an example, its pitch P = 1.5mm, meaning that for every rotation of the adjusting bolt (360°), its axial displacement is only 1.5mm. The operator can achieve extremely high feed resolution by controlling the rotation angle (e.g., a 60° rotation corresponds to an axial displacement of 0.25mm). The external thread of the adjusting bolt 2 and the internal thread of the threaded guide hole on the tool body 1 form a precision helical transmission pair.

[0026] The front end of the adjusting bolt 2 (i.e., the end that extends into the bayonet) is provided with an abutment end. Preferably, this abutment end can be machined into a spherical crown shape or a flat shape. The spherical crown-shaped end can automatically adapt to any slight inclination that may exist on the upper surface of the scavenging manifold flange, ensuring point contact or small-area contact and preventing localized flange crushing due to eccentric loads. The rear end of the adjusting bolt 2 (i.e., the end exposed above the upper support arm) is fixedly provided with a force-applying head, which is a standard external hexagonal head or internal hexagonal countersunk head, facilitating rotational force application with a torque wrench or a standard open-end wrench.

[0027] The following is a detailed explanation of the specific implementation method for adjusting the clearance between the scavenging manifold and the frame plane using this tool, based on an actual workshop operation scenario. The operation target is the scavenging manifold closing station of a large marine low-speed diesel engine, and the goal is to uniformly control the clearance between the lower plane of the scavenging manifold flange A and the frame plane B within the range of 0.10mm to 0.15mm.

[0028] Step S1: Tooling Installation and Benchmark Establishment Insert the open bayonet of fixture body 1 horizontally from the side into the outer side of the mating area between the scavenging manifold flange and the frame plane. After insertion, ensure that the inner precision-fitting surface of the lower support arm of fixture body 1 is completely fitted onto the frame plane; at this point, the lower support arm serves as a fixed base support. Simultaneously, visually check whether the front end of the adjusting bolt 2 is aligned with the center stress area on the upper surface of the scavenging manifold flange. During installation, multiple sets (usually 4-6 sets) of this fixture can be evenly spaced along the circumference of the flange edge, depending on the pipe diameter of the scavenging manifold and the flange width, to facilitate multi-point synchronous or alternating adjustment of the clearance.

[0029] Step S2: Initial gap measurement and adjustment calculation After installing the tooling, the operator uses a standard feeler gauge to check the actual clearance between the lower plane of the scavenging manifold flange and the frame plane at multiple points. Let the measured minimum clearance be H. min The maximum gap is H max The target gap value is preset to T=0.12mm (a value between 0.10 and 0.15mm can be used). If the current measured gap H at a certain detection point... cur If the gap is greater than 0.15mm, then the gap at that point needs to be reduced by ΔH = H. cur -0.12 (mm). Based on the pitch P of the adjusting bolt (e.g., P=1.5mm), calculate the required theoretical rotation angle: θ = (ΔH / P) × 360°. For example, if the measured gap is 0.55mm, then ΔH needs to be reduced by 0.55-0.12=0.43mm, corresponding to a rotation angle θ≈(0.43 / 1.5)×360°≈103°.

[0030] Step S3: Rotation drive and real-time dynamic fine-tuning The operator uses a wrench to hold the force-applying head at the rear end of adjusting bolt 2. Initial rotation is performed according to the direction (clockwise rotation to reduce clearance) and angle calculated in step S2. During rotation, adjusting bolt 2 undergoes precise axial displacement under the constraint of the threaded guide hole. Its abutting end pushes downwards quantitatively against the upper surface of the scavenging manifold flange, forcing the entire scavenging manifold closer to the frame plane, thereby reducing the clearance.

[0031] During the rotation operation, the operator must continuously monitor the clearance value using a feeler gauge. A strategy of "rotating and feeding approximately 80% of the calculated angle, pausing and measuring the clearance, and then finely adjusting in 10°~15° increments based on the remaining deviation between the measured and target values" is adopted until the clearance at the detection point stabilizes within the range of 0.10mm~0.15mm. During this process, excessively large single rotation angles are strictly prohibited to prevent overpressure that could deform the scavenging manifold or damage the frame.

[0032] Step S4: Multi-point coordinated adjustment For multiple sets of tooling arranged along the flange circumference, the fine-tuning operation of step S3 above should be performed in a symmetrical and intersecting order (e.g., points 1, 3, 5 and points 2, 4, 6) to avoid flange warping or stress concentration caused by excessive adjustment on one side. After each round of adjustment, the gap at all points must be re-measured until the gap value of all test points stably meets the requirement of 0.10mm~0.15mm.

[0033] Step S5: Locking and Final Tightening After all the gaps at the inspection points are adjusted to be within acceptable limits, keep the adjusting bolts 2 of each tooling in a slightly pre-tightened state (the recommended pre-tightening torque is controlled between 50 and 80 N·m), and use this tooling to temporarily assist in positioning the scavenging manifold. Then, immediately follow the diesel engine assembly process specifications to complete the final tightening of the bolts connecting the scavenging manifold flange to the engine frame (including tightening in stages according to the specified torque and sequence). After all the connecting bolts have reached the specified torque and anti-loosening measures have been implemented, rotate the adjusting bolts 2 of each tooling in the reverse direction to completely release the tightening force. Finally, pull the main body 1 of the tooling laterally and remove the tooling.

Claims

1. A special adjustment tooling for the clearance of scavenging manifolds in large ships, characterized in that, include: The tooling body has a "U"-shaped opening structure, including an upper support arm, a lower support arm, and a vertical connecting arm fixedly connected between the upper and lower support arms. An open bayonet is formed between the upper and lower support arms for side mounting to the outer edge of the scavenging manifold flange. The upper support arm has a threaded guide hole that penetrates vertically along its thickness direction, and the inner wall of the threaded guide hole has an internal thread. The inner surface of the lower support arm is a precision-machined reference contact surface, which is used to tightly fit against the frame plane when the tooling is mounted, so as to serve as a fixed reference surface during the clearance adjustment process. An adjusting bolt is inserted into the threaded guide hole. The shank of the adjusting bolt has an external thread, which, together with the internal thread of the threaded guide hole, forms a helical drive pair. The front end of the adjusting bolt has an abutment end for pressing against the upper surface of the scavenging manifold flange, and the rear end of the adjusting bolt has a force-applying head for cooperating with a rotating tool to apply force. The threaded pair between the adjusting bolt and the threaded guide hole is a fine thread pair. The upper support arm serves as a reaction support seat. When the adjusting bolt rotates, it generates an axial feed displacement relative to the tooling body. Its front end abuts against the scavenging manifold flange and applies a downward pushing force. Under the action of the fixed reference reaction force of the lower support arm, the scavenging manifold flange is quantitatively pushed towards the machine frame plane to achieve precise fine adjustment of the gap between the scavenging manifold and the machine frame plane.

2. The special adjustment tooling for the clearance of the scavenging manifold of large ships according to claim 1, characterized in that, The contact end has a spherical crown-shaped structure or a planar structure.

3. The special adjustment tooling for the clearance of the scavenging manifold of large ships according to claim 1, characterized in that, The upper support arm, lower support arm and vertical connecting arm of the tooling body (1) are integral forged structures, or integral structures formed by welding the components separately and annealing to eliminate stress.

4. A method for adjusting the clearance of a scavenging manifold using a special adjusting tool for the clearance of a large ship's scavenging manifold as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Arrange multiple sets of the aforementioned tooling at intervals along the circumference of the scavenging manifold flange. Horizontally mount the main body of each tooling across the outside of the mating area between the scavenging manifold flange and the machine frame plane via its open bayonet side. Ensure that the inner reference contact surface of the lower support arm of each tooling is tightly attached to the machine frame plane, and align the abutting end of the adjusting bolt of each tooling with the corresponding force point on the upper surface of the scavenging manifold flange. Step 2: Use testing tools to measure the actual gap between the lower plane of the current scavenging manifold flange and the frame plane at each arrangement point, record the initial gap at each point, and determine the required displacement at each point based on the difference between the measured gap value and the preset target gap value. Step 3: Based on the required displacement and thread pitch of the adjusting bolts at each point, calculate the required rotation angle of each tooling adjusting bolt. Then, rotate each adjusting bolt one by one to make each adjusting bolt axially displace relative to the tooling body. The abutting end of the bolt pushes the scavenging manifold flange downward, gradually reducing the gap between the scavenging manifold and the frame plane at each point. Step 4: During the rotation of each adjusting bolt, use a testing tool to monitor the change in the gap value at each point in real time. Then, rotate and fine-tune the adjusting bolts of the tooling located in different positions in a symmetrical and intersecting order until the gap value at all points is stable within the target range of 0.10mm to 0.15mm.

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