A special wrench for aero-engine rear hanger point lock pin

Abstract

The utility model discloses a special wrench of aero-engine rear hanging point lock pin, including sleeve, screw rod and stop screw cap, one end of sleeve is closed and is equipped with the thread hole of adapting with the stem of screw rod on this closed face, the other end of sleeve is the open end to enter the internal space of sleeve for the lock pin of dismounting middle movement, one end of screw rod is as first end thread connection stop screw cap, and the other end is as second end and passes through the inside of sleeve and comes out from the thread hole along the axial direction, and the thread on the first end of screw rod is opposite with the spiral direction of the thread on the stem between two ends. The utility model discloses the synergic structure of screw rod and stop screw cap, and the dual effect of "axial tension" and "sleeve thrust" is converted to "rotary force", realizes the synchronous operation of "edge tightening edge pulling out" of lock pin, and the efficiency of traditional hammering method dismounting lock pin is improved by more than 80%, can realize the safe, efficient and non - damaging dismounting of lock pin.

Description

Technical Field

[0001] This utility model belongs to the technical field of high-precision maintenance equipment for aero-engines, specifically relating to a special puller for the locking pin of the rear suspension point of an aero-engine. Background Technology

[0002] As the core power unit of an aircraft, the assembly and maintenance precision of its components directly affects flight safety and reliability. A certain type of engine, a mainstream commercial aircraft engine, has its rear mounting point 8 rigidly connected to a pair of engine mounting lugs 9 via locking pins 10. Figure 1 As shown, both the rear suspension point 8 and the lug 9 have through holes for the locking pin to pass through. The locking pin 10 is a cylinder with a hole in the middle, and the left end face of the locking pin 10 protrudes from the surface of the left lug 9. An annular protrusion 12 is provided at the edge of the through hole of the lug 9. This locking pin needs to be removed during engine maintenance, repair, or parts replacement.

[0003] Currently, the industry mainly relies on traditional methods to disassemble such locking pins: using an extended rod as a force transmission rod, applying impact force to one end of the locking pin by hammering the force transmission rod, and using brute force to pull the locking pin out of the connection position.

[0004] This method has the following significant drawbacks:

[0005] 1. Low operating efficiency: It requires repeated hammering and adjustment of the force angle, which is time-consuming and labor-intensive. The average time for a single disassembly is 27 minutes.

[0006] 2. High risk of damage: The impact force can easily cause the locking pin to deform or break. At the same time, the hard friction between the extension rod and the mounting lug will scratch the surface of the engine mounting lug (usually made of precision-machined aluminum alloy or titanium alloy), which will damage the fit accuracy and cause a decrease in the accuracy of repeated assembly.

[0007] 3. Poor safety: During the impact, the locking pin may suddenly come out due to uneven force, posing a safety hazard of throwing the operator.

[0008] 4. Lack of specialization: The OEM (Original Equipment Manufacturer) does not provide a special disassembly tool for this locking pin. The existing tools are only general-purpose auxiliary parts and cannot meet the needs of precision maintenance. Utility Model Content

[0009] The purpose of this utility model is to provide a special puller for the rear suspension point lock pin of an aircraft engine that is simple in structure, low in cost, and can achieve safe, efficient, and damage-free disassembly of the lock pin.

[0010] The purpose of this utility model is achieved through the following technical measures: a special puller for the rear suspension point locking pin of an aircraft engine, characterized in that it includes a sleeve, a screw, and a locking nut. One end of the sleeve is closed and a threaded hole adapted to the body of the screw is provided on the closed surface. The other end of the sleeve is an open end to allow the locking pin, which moves during disassembly, to enter the internal space of the sleeve. One end of the screw is threaded to the locking nut as a first end, and the other end is threaded to the inside of the sleeve axially as a second end and exits through the threaded hole. The helical direction of the thread on the first end of the screw is opposite to that of the thread on the body between the two ends.

[0011] This utility model, through the synergistic structure of the screw and the locking nut, transforms the "rotational force" into the dual action of "axial tension" and "sleeve thrust," achieving simultaneous "tightening and pulling out" of the locking pin. This improves the efficiency of disassembling the locking pin by more than 80% compared to the traditional hammering method, enabling safe, efficient, and damage-free disassembly of the locking pin.

[0012] The sleeve of this invention has an annular step on the inner wall of the open end that matches the convex edge of the lug hole.

[0013] The screw of this invention has a boss at the second end for applying force with a wrench.

[0014] The sleeve of this utility model consists of a first cylindrical body and a second cylindrical body. The first cylindrical body is made of stainless steel alloy, and the second cylindrical body is made of aluminum alloy. One end of the first cylindrical body is threaded to one end of the second cylindrical body. The closed surface of the sleeve is located on the other end of the first cylindrical body, and the annular step is located on the other end of the second cylindrical body. This utility model adopts a segmented sleeve design of stainless steel alloy and aluminum alloy, which not only ensures the overall structural strength of the sleeve (tensile strength of the stainless steel section ≥ 800 MPa), but also avoids frictional damage to the engine mount lug by utilizing the low hardness characteristics of the aluminum alloy section (HV ≤ 100), thus overcoming the defect of traditional tools being "hard contact vulnerable parts".

[0015] The screw surface of this invention is nitrided, with a surface hardness ≥ HV600, ensuring fatigue resistance under high loads.

[0016] The second cylindrical body of this invention is polished or coated with a diamond-like coating, resulting in a hardness of HV≤100. This is significantly lower than that of commonly used engine mounting lug materials (such as aluminum alloy HV120-150), thus avoiding friction damage.

[0017] Compared with the prior art, the present invention has the following significant advantages:

[0018] (1) This utility model transforms the "rotational force" into the dual action of "axial tension" and "sleeve thrust" through the synergistic structure of the screw and the locking nut, realizing the simultaneous operation of "tightening and pulling out" of the locking pin, which improves the efficiency of disassembling the locking pin by more than 80% compared with the traditional hammering method.

[0019] (2) This utility model solves three major industry problems caused by traditional disassembly methods, namely, damage to the locking pin, scratches on the engine body, and operational safety hazards, through material gradient design, mechanical transmission optimization, and aerospace-grade surface treatment technology, and meets the requirements of the AS9100D aerospace quality management system.

[0020] (3) This utility model has significant economic benefits. It can reduce disassembly time by 19.5 minutes and greatly reduce the scrap rate of locking pins. It provides a dedicated, efficient and reliable tool solution for the maintenance of a certain type of aircraft engine, and has significant practical value and industry promotion significance. Attached Figure Description

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Figure 1 This is a schematic diagram showing the connection between the rear mounting point and the mounting lug of an aircraft engine via locking pins;

[0023] Figure 2 This is the front view of this utility model;

[0024] Figure 3 This is the left view of this utility model;

[0025] Figure 4 It is along Figure 3 Sectional view of line AA in the middle;

[0026] Figure 5 This is a three-dimensional structural schematic diagram of the present invention;

[0027] Figure 6 This is a block diagram illustrating the working principle of this utility model.

[0028] In the diagram: 1-sleeve, 2-screw, 3-locking nut, 4-bore, 5-flange connection structure, 6-first cylinder, 7-second cylinder, 8-rear lifting point, 9-hanging lug, 10-locking pin, 11-annular step, 12-protruding edge, 13-center hole. Detailed Implementation

[0029] like Figures 2 to 5As shown, this utility model discloses a special puller for a rear suspension point locking pin of an aircraft engine, including a sleeve 1, a screw 2, and a locking nut 3. One end (left end) of the sleeve 1 is closed, and a threaded hole adapted to the rod body of the screw 2 is provided on the closed surface. The other end of the sleeve 1 is an open end to allow the locking pin 10, which moves during disassembly, to enter the internal space of the sleeve 1. The internal space of the sleeve 1 is adapted to the locking pin 10. One end (right end) of the screw 2 is threadedly connected to the locking nut 3 as the first end, and the outer diameter of the locking nut 3 is larger than the diameter of the center hole 13 of the locking pin 10. The other end (left end) of the screw 2 is axially passed through the interior of the sleeve 1 and exits through the threaded hole. The helical direction of the thread on the first end of the screw 2 is opposite to that of the thread on the rod body between the two ends.

[0030] The inner wall of the open end of the sleeve 1 is provided with an annular step 11 that matches the protruding edge 12 along the through hole of the lug 9. The second end of the screw 2 is provided with a regular hexagonal prism boss 4 for applying force with a wrench. The boss 4 is integrally formed with the body of the screw 2.

[0031] Sleeve 1 consists of a first cylindrical body 6 and a second cylindrical body 7. The first cylindrical body 6 is made of stainless steel alloy and serves as a support section, used to adapt to the engine rear mounting point structure around the locking pin, providing structural strength. The second cylindrical body 7 is made of aluminum alloy, with its surface polished or treated with a diamond-like coating, achieving a hardness of HV≤100. The second cylindrical body 7 is in direct contact with the engine mounting lug 9. One end (right end) of the first cylindrical body 6 is threaded to one end (left end) of the second cylindrical body 7 (i.e., fixedly connected via flange connection structure 5). The closed surface of sleeve 1 is located on the other end (left end) of the first cylindrical body 6, and the annular step 11 is located on the other end of the second cylindrical body 7.

[0032] The screw 2 is made of high-strength alloy steel. The screw has two threads: one end is a reverse thread (left-hand thread) that mates with the internal thread of the stop nut 3; the other end is a right-hand thread (right-hand thread) that mates with the internal thread of the threaded hole on the first cylinder 6. The surface of the screw 2 is nitrided and has a surface hardness ≥ HV600 to ensure fatigue resistance under high load.

[0033] The locking nut 3 is a nut structure, and the nut is prismatic (such as a regular hexagonal prism) to facilitate the application of force by tools.

[0034] This utility model achieves the disassembly of the locking pin through a mechanical linkage mechanism of "forward tightening - synchronous traction", such as Figure 6 As shown, the working principle is as follows:

[0035] (1) Pre-fixing stage: Gently place the aluminum alloy section (second cylinder) of the entire sleeve against the surface of the engine mounting lug, and slowly move it around the locking pin until the aluminum alloy section and the surface of the mounting lug are in close contact without gap (at this time, the protruding edge at the through hole of the mounting lug is located on the step inside the right end of the sleeve, and the left end of the locking pin extends into the sleeve), ensuring that the contact pressure between the aluminum alloy section and the surface of the engine mounting lug is ≤0.5MPa; the screw passes through the center hole of the locking pin and extends out from its other end, and then the locking nut is screwed onto the extended end of the screw until it is tightly fitted with the head of the locking pin (fixed by the self-locking force of the thread, the locking force is ≥5kN).

[0036] (2) Force application stage: Use a special wrench (such as a ratchet wrench) to hold the boss of the screw and rotate the screw clockwise. At this time, the positive thread section of the screw pushes the sleeve to move towards the locking pin (the sleeve fits with the rear lifting point structure and provides a reaction force), while the negative thread section of the screw drives the stop nut to move synchronously towards the head of the screw (i.e., pull towards the sleeve).

[0037] (3) Lock pin removal stage: As the screw continues to tighten, the stop nut applies a continuous axial pull on the lock pin, while the sleeve moves synchronously towards the screw, gradually pulling the lock pin out from the rear lifting point connection position; since the aluminum alloy section is in soft contact with the lug and the pull force is evenly transmitted, hard friction and local stress concentration are avoided, ensuring that the engine body is not damaged.

[0038] The specific usage process of this utility model is as follows:

[0039] (1) Preparation: Confirm that the engine is in a stopped and cooled state, remove the surrounding shielding parts after lifting, and clean the locking pin and surrounding area (to avoid impurities affecting assembly accuracy); and confirm that there is no deformation of each part of the puller (sleeve straightness ≤ 0.1mm) and no damage to the threads (fitting clearance ≤ 0.02mm, and no burrs in the locking groove of the locking nut).

[0040] (2) Installation and positioning: Gently place the aluminum alloy section of the entire sleeve (second cylinder) against the surface of the engine mounting lug, and slowly move it around the locking pin until the aluminum alloy section and the surface of the mounting lug are in close contact without gaps. Ensure that the contact pressure between the aluminum alloy section and the surface of the engine mounting lug is ≤0.5MPa. Then insert the screw into the locking pin. After ensuring that the screw is fully inserted into the locking pin, put the locking nut on the first end. (3) Locking pin fixing: Rotate the locking nut to make it fit tightly against the head of the locking pin (the fit can be checked by hand or feeler gauge). Fix it by the self-locking force of the thread. The locking force is ≥5kN. Use a torque wrench to pre-tighten to 25N·m.

[0041] (4) Disassembly by applying force: Install a special wrench (such as a ratchet wrench) on the boss of the screw, and gradually increase the rotation torque in increments of 10 N·m / time (maximum torque ≤ 100 N·m). Observe whether the sleeve is evenly attached to the rear lifting point (if there is any skew, pause and adjust the screw angle); when the torque increases to 25 N·m, the locking pin is pushed by the stop nut and begins to move noticeably (which can be monitored through the observation hole on the end face of the rear lifting point). The locking pin gradually moves into the inside of the sleeve. If the locking pin protrudes ≥ 5 mm from the end face of the rear lifting point, reduce the torque increment (5-8 N·m / time) until the locking pin is completely disengaged from the connection position; finally, disassembly is completed with a torque of 53 N·m, and the total time is about 7.5 minutes.

[0042] (5) Tool maintenance: After disassembly, rotate the screw in the opposite direction to remove the stop nut, clean all parts of the puller, clean the sleeve, screw and nut with anhydrous ethanol, apply anti-rust oil, wipe the surface of the aluminum alloy section with a soft cloth to remove the oxide layer, and store in a dry tool cabinet.

[0043] The structural design features of this utility model are:

[0044] 1. Gradient hardness design: The sleeve is designed with a combination of stainless steel alloy and aluminum alloy. This design ensures the overall structural strength of the sleeve (tensile strength of the stainless steel section ≥ 800 MPa) while the aluminum alloy section has low hardness (HV ≤ 100). The hardness of aluminum alloy HB80 is only 84% of that of the lug material (HB95), forming a passive protective layer. This avoids frictional damage to the engine lug and overcomes the defect of traditional tools being "hard contact vulnerable parts".

[0045] 2. Optimized force transmission: The synergistic structure of the screw and the locking nut transforms the "rotational force" into the dual action of "axial tension" and "sleeve thrust", realizing the simultaneous operation of "tightening and pulling out" of the locking pin, which improves efficiency by more than 80% compared with the traditional hammering method (the single locking pin disassembly time is shortened from 20-25 minutes to 7.5 minutes).

[0046] Dual-thread force coupling: The reverse thread lead of 1.5mm and the positive thread lead of 2.5mm form a force amplification factor of 1.67. Verification formula: F out=2πT(1 / P-1 / P2).

[0047] 3. By controlling the limited torque of the screw (maximum tension ≤ 50kN, lower than 80% of the yield strength of the locking pin material), the risk of the locking pin breaking or suddenly coming out due to overload is avoided, improving operational safety by 60%.

[0048] 4. Damage prevention redundancy: All parts have a chamfered edge of R0.5mm to eliminate stress concentration points.

[0049] 5. Customized design for the rear lifting point structure (such as lug size and locking pin installation angle) of a certain engine model (sleeve inner diameter tolerance ±0.05mm, screw pitch and locking pin thread matching), solving the industry problem of OEMs lacking special tools, with 100% compatibility.

[0050] The embodiments of this utility model are not limited thereto. Based on the above content of this utility model, and in accordance with the common technical knowledge and conventional means in the field, without departing from the basic technical idea of ​​this utility model, this utility model can also be modified, replaced or changed in various other forms, all of which fall within the scope of protection of this utility model.

Claims

1. A special puller for the rear suspension point locking pin of an aircraft engine, characterized in that: The device includes a sleeve, a screw, and a locking nut. One end of the sleeve is closed and has a threaded hole on the closed surface that matches the body of the screw. The other end of the sleeve is open to allow a locking pin that can be moved during disassembly to enter the internal space of the sleeve. One end of the screw is threaded to the locking nut as the first end, and the other end is threaded through the inside of the sleeve axially as the second end and exits through the threaded hole. The helical direction of the thread on the first end of the screw is opposite to that of the thread on the body between the two ends.

2. The special puller for the rear suspension point locking pin of an aero-engine according to claim 1, characterized in that: The inner wall of the open end of the sleeve is provided with an annular step that matches the convex edge of the lug hole.

3. The special puller for the rear suspension point locking pin of an aero-engine according to claim 2, characterized in that: The second end of the screw is provided with a prismatic boss for applying force with a wrench.

4. The special puller for the rear suspension point locking pin of an aero-engine according to claim 3, characterized in that: The sleeve is composed of a first cylinder and a second cylinder. The first cylinder is made of stainless steel alloy, and the second cylinder is made of aluminum alloy. One end of the first cylinder is threaded to one end of the second cylinder. The closed surface of the sleeve is located on the other end of the first cylinder, and the annular step is located on the other end of the second cylinder.

5. The special puller for the rear suspension point locking pin of an aero-engine according to claim 4, characterized in that: The screw surface is nitrided, and the surface hardness is ≥HV600.

6. The special puller for the rear suspension point locking pin of an aero-engine according to claim 5, characterized in that: The surface of the second cylinder is polished or coated with a diamond-like coating, and the hardness is HV≤100.

Images