阅读说明：本技术 尾桨桨距操纵轴装置及其制备方法 (Tail rotor pitch control shaft device and preparation method thereof ) 是由 潘文斌 吴红美 艾永生 陈金 张川 于 2020-04-21 设计创作，主要内容包括：本发明公开了一种尾桨桨距操纵轴装置及其制备方法,包括：尾桨轴,桨距操纵轴,桨距操纵轴设有用于与尾桨轴的内花键配合的导向外花键,助力器操纵杆,支撑组件,支撑组件包括第一支撑件、第二支撑件和第三支撑件；第一支撑件包括套设在导向外花键的第一滑套；第二支撑件包括套设在桨距操纵轴上远离助力器操纵杆的一端的第二滑套和方形圈；第三支撑件包括用于与减速器机匣内孔配合并安装在轴承的轴承衬套上的活塞密封圈。本发明的尾桨桨距操纵轴装置,采用三点支撑,保证桨距操纵轴平稳的进行操纵运动,减少桨距操纵轴与尾桨助力器操纵杆的不对中,减轻由于偏载引起的弯矩,降低桨距操纵轴以及轴承的磨损或过热等故障。(The invention discloses a tail rotor pitch control shaft device and a preparation method thereof, wherein the tail rotor pitch control shaft device comprises the following steps: the propeller pitch control device comprises a tail propeller shaft, a pitch control shaft, a booster control lever and a support assembly, wherein the pitch control shaft is provided with a guide external spline matched with an internal spline of the tail propeller shaft; the first supporting piece comprises a first sliding sleeve sleeved on the guide external spline; the second supporting piece comprises a second sliding sleeve and a square ring, wherein the second sliding sleeve is sleeved on one end of the propeller pitch control shaft, which is far away from the booster control rod; the third support member includes a piston seal ring for mating with the reducer case bore and mounting on the bearing bushing of the bearing. The tail rotor pitch control shaft device adopts three-point support, ensures the stable control motion of the pitch control shaft, reduces the misalignment between the pitch control shaft and the control lever of the tail rotor booster, lightens bending moment caused by unbalance loading, and reduces the faults of abrasion or overheating of the pitch control shaft and a bearing and the like.)

1. A tail rotor pitch control shaft device is characterized in that,

the method comprises the following steps: the propeller shaft (1) is matched and connected with an internal spline (11) of the propeller shaft (1) and reciprocates along the axial direction of the internal spline (11) of the propeller shaft (1) to realize a propeller pitch control shaft (2) for pitch control of a propeller tail blade,

the pitch control shaft (2) is provided with a guide external spline (21) used for being matched with an internal spline (11) of the tail rotor shaft (1), a booster control rod (4) which is arranged at the first free end of the pitch control shaft (2) and is in transmission connection with the pitch control shaft (2) through a bearing (3), and a support assembly used for supporting the pitch control shaft (2) to axially control and reciprocate, wherein the support assembly comprises a first support piece (5), a second support piece (6) and a third support piece (7);

the first supporting piece (5) comprises a first sliding sleeve sleeved on the guide external spline (21);

the second supporting piece (6) comprises a second sliding sleeve and a square ring, wherein the second sliding sleeve and the square ring are sleeved at one end, far away from the booster operating rod (4), of the propeller pitch operating shaft (2);

the third support member (7) comprises a piston seal ring for engaging with the reducer casing bore and being mounted on a bearing bushing (31) of the bearing (3).

2. Tail-rotor pitch steering shaft arrangement according to claim 1,

the pitch control shaft (2) is of a hollow columnar structure, and a mounting part (22) for mounting and positioning the pitch control shaft (2) and the bearing (3) is arranged at the first end of the pitch control shaft (2);

the mounting part (22) is circumferentially provided with a bearing nut which is used for tightly matching the pitch control shaft (2) with the bearing (3), the booster control lever (4) is provided with the bearing (3) and a bearing seat (32), the bearing (3) is clamped between the bearing seat (32) and the pitch control shaft (2), and the bearing (3) and the bearing seat (32) are jointly inserted from the first end of the pitch control shaft (2) and fixed at the position of the bearing nut so as to realize the mounting and positioning of the pitch control shaft (2) and the bearing (3);

a groove structure (221) for observing the assembling condition of the pitch control shaft (2) and the bearing (3) is arranged at the central hole of the mounting part (22);

installation department (22) surface is equipped with and is used for pitch control axle (2) with waist shape hole (222) of bearing (3) axial locking lay when pitch control axle (2) assemble the tip of pitch control axle (2) be used for with waist shape hole (222) joint complex snap ring (8).

3. A tail rotor pitch steering shaft arrangement according to claim 2,

the number of the waist-shaped holes (222) is two, and the two waist-shaped holes (222) are symmetrically distributed on the outer surface of the mounting part (22);

the groove structures (221) are four, and the groove structures (221) are circumferentially arranged at intervals along the central hole of the mounting part (22).

4. A tail rotor pitch steering shaft arrangement according to claim 2,

the bearing (3) adopts a double-row angular contact ball bearing.

5. A tail rotor pitch steering shaft arrangement according to claim 2,

a flange edge structure (23) is arranged at the second end of the pitch control shaft (2), and bolt holes (231) for being connected with the fork-shaped piece (9) through bolts are distributed in the flange edge structure (23) so that the bolts can be placed into the pitch control shaft (2) from the second end;

the bolt holes (231) are arranged in multiple groups, and the bolt holes (231) are circumferentially arranged at intervals along the flange edge structure (23);

each group of bolt holes (231) are arranged in a plurality of equal intervals.

6. Tail-rotor pitch steering shaft arrangement according to claim 1,

the pitch control shaft (2) is made of an aluminum alloy material; and/or

The first supporting piece (5) is prepared from a graphite material; and/or

The second supporting piece (6) is made of graphite materials; and/or

The third supporting piece (7) is prepared by an outer layer made of polytetrafluoroethylene and a wrapping inner layer made of steel springs.

7. A method for producing a tail rotor pitch steering shaft device, which obtains the tail rotor pitch steering shaft device of claim 6,

the method comprises the following steps:

carrying out chemical nickel plating treatment on the outer surface of the guide external spline (21);

and a matching surface (24) which is arranged on the propeller pitch control shaft (2) and is contacted with the second sliding sleeve and the square ring is sprayed with chromium oxide.

8. Method for producing a tail rotor pitch steering shaft arrangement according to claim 7,

the chemical nickel plating treatment comprises the following specific steps:

a. pretreatment: carrying out chemical degreasing, corrosion, nitric acid brightening and zinc dipping on a to-be-plated base body of the aluminum alloy, and protecting a non-plated surface;

b. alkaline chemical nickel preplating: carrying out chemical nickel preplating on the pretreated substrate to be plated by adopting an alkaline preplating solution to obtain a preplated piece, wherein the pH value of the alkaline preplating solution is 8.5-9.2, the temperature of the chemical nickel preplating is 24-40 ℃, and the time is 4-10 min;

c. chemical nickel plating: carrying out chemical nickel plating on the pre-plated part by adopting a chemical plating solution, wherein the pH value of the chemical plating solution is 4.4-5, the temperature of the chemical nickel plating is 85-92 ℃, and the deposition rate of the chemical nickel plating is 8-12 mu m/h;

d. and (3) heat treatment: and (3) carrying out heat treatment on the finished product after the chemical plating, wherein the heat treatment temperature is 150-170 ℃, the heat treatment time is 10-12 h, and cooling to finish the chemical nickel plating treatment.

9. Method for producing a tail rotor pitch steering shaft arrangement according to claim 8,

the specific steps of the spray chromium oxide treatment comprise:

chromium oxide powder is sprayed on the matching surface (24) of the pitch control shaft (2) through a plasma spraying device, the temperature of the matching surface (24) is controlled to be lower than 160 ℃ during spraying, and grinding is carried out to form a chromium oxide coating.

10. Method for producing a tail rotor pitch steering shaft arrangement according to claim 7,

the method further comprises the step of carrying out defect tolerance design and defect tolerance test on the pitch control shaft (2).

Technical Field

The invention relates to the field of tail reducers of helicopters, in particular to a tail rotor pitch control shaft device. Furthermore, the invention also relates to a preparation method of the tail rotor pitch control shaft device.

Background

The helicopter tail reducer tail rotor pitch control shaft is a key part which is arranged in the tail rotor shaft and reciprocates along the axis to control the pitch of a tail rotor blade, the conventional typical structure is shown in figure 1, the tail rotor pitch control shaft arranged in the tail rotor shaft is pushed in a reciprocating mode in the axial direction of a tail rotor booster control lever, and a guide key of the tail rotor pitch control shaft reciprocates in the axial direction along a guide groove of a guide cylinder to realize the pitch control of the tail rotor blade. The guide cylinder is generally made of aluminum, a guide key of a tail rotor pitch control shaft reciprocates in a guide groove of the aluminum guide cylinder, and the guide groove is easy to have heavy abrasion. The supporting piece is arranged between the tail rotor pitch control shaft and the tail rotor shaft, the supporting piece is generally arranged at the front end and the rear end of the tail rotor pitch control shaft, but the tail rotor pitch control shaft is complex in structure and easy to cause serious abrasion and structural deformation through long-term repeated friction, so that the stability and reliability of the whole control system are poor, and potential safety hazards exist.

Disclosure of Invention

The invention provides a tail rotor pitch control shaft device and a preparation method thereof, and aims to solve the technical problems that the conventional tail rotor pitch control shaft is frequently moved, is easily abraded to cause structural deformation, and the service life of parts is shortened.

The technical scheme adopted by the invention is as follows:

a tail rotor pitch steering shaft arrangement comprising: the propeller pitch control device comprises a tail propeller shaft, a propeller pitch control shaft, a booster control lever and a support assembly, wherein the tail propeller shaft is used for being matched and connected with an inner spline of the tail propeller shaft and reciprocating along the axial direction of the inner spline of the tail propeller shaft so as to realize pitch control of a propeller tail blade; the first supporting piece comprises a first sliding sleeve sleeved on the guide external spline; the second supporting piece comprises a second sliding sleeve and a square ring, wherein the second sliding sleeve and the square ring are sleeved at one end, far away from the booster operating rod, of the propeller pitch operating shaft; the third support member includes a piston seal ring for mating with the reducer case bore and mounting on the bearing bushing of the bearing.

Furthermore, the pitch control shaft is of a hollow columnar structure, and a first end of the pitch control shaft is provided with an installation part for installing and positioning the pitch control shaft and the bearing; the installation part is circumferentially provided with a bearing nut which is used for tightly matching the propeller pitch control shaft with the bearing, the booster control shaft is provided with a bearing and a bearing seat, the bearing is clamped between the bearing seat and the propeller pitch control shaft, the bearing and the bearing seat are jointly inserted into the position of the bearing nut from the first end of the propeller pitch control shaft and are fixed at the position of the bearing nut so as to realize the installation and the positioning of the propeller pitch control shaft and the bearing, and the central hole of the installation part is provided with a groove structure which is used for observing the assembly condition; the outer surface of the mounting part is provided with a kidney-shaped hole for axial locking of the pitch control shaft and the bearing, and a snap ring which is arranged at the end part of the pitch control shaft and is used for clamping and matching with the kidney-shaped hole is arranged when the pitch control shaft is assembled.

Furthermore, two waist-shaped holes are adopted, and the two waist-shaped holes are symmetrically distributed on the outer surface of the mounting part; the groove structures are four and are circumferentially arranged at intervals along the central hole of the mounting part.

Further, the bearing adopts a double-row angular contact ball bearing.

Further, a flange edge structure is arranged at the second end of the pitch control shaft, and bolt holes for being connected with the fork-shaped part through bolts are distributed in the flange edge structure, so that the bolts can be placed into the pitch control shaft from the second end of the pitch control shaft; a plurality of groups of bolt holes are arranged at intervals along the circumferential direction of the flange edge structure; each group of bolt holes are arranged in a plurality of equidistant mode.

Further, the pitch control shaft is made of an aluminum alloy material; and/or the first support is prepared from a graphite material; and/or the second support is prepared from graphite materials; and/or the third supporting piece is prepared by adopting polytetrafluoroethylene as an outer layer and a steel spring as a wrapping inner layer.

According to another aspect of the present invention, there is also provided a method for preparing a tail rotor pitch steering shaft device, which obtains the above-mentioned tail rotor pitch steering shaft device, including the steps of: performing chemical nickel plating treatment on the outer surface of the guide external spline; and chromium oxide is sprayed on the matching surface of the propeller pitch control shaft, which is contacted with the second sliding sleeve and the square ring.

Further, the chemical nickel plating treatment comprises the following specific steps:

a. pretreatment: carrying out chemical degreasing, corrosion, nitric acid brightening and zinc dipping on a to-be-plated base body of the aluminum alloy, and protecting a non-plated surface;

b. alkaline chemical nickel preplating: carrying out chemical pre-nickel plating on the pretreated matrix to be plated by adopting an alkaline pre-plating solution to obtain a pre-plated part, wherein the pH value of the alkaline pre-plating solution is 8.5-9.2, the temperature of the chemical pre-nickel plating is 24-40 ℃, and the time is 4-10 min;

c. chemical nickel plating: chemical nickel plating is carried out on the pre-plated piece by adopting chemical plating solution, the pH value of the chemical plating solution is 4.4-5, the temperature of the chemical nickel plating is 85-92 ℃, and the deposition rate of the chemical nickel plating is 8-12 mu m/h;

d. and (3) heat treatment: and (3) carrying out heat treatment on the finished product after the chemical plating, wherein the heat treatment temperature is 150-170 ℃, the heat treatment time is 10-12 h, and cooling to finish the chemical nickel plating treatment.

Further, the specific steps of the chromium oxide spraying treatment comprise: and spraying chromium oxide powder on the matching surface of the pitch control shaft by using plasma spraying equipment, controlling the temperature of the matching surface to be lower than 160 ℃ in the spraying process, and grinding to form a chromium oxide coating.

Further, the method further comprises the step of carrying out defect tolerance design and defect tolerance test on the pitch control shaft.

The invention has the following beneficial effects:

the invention relates to a tail rotor pitch control shaft device, which comprises a tail rotor shaft, a pitch control shaft and a booster control lever, wherein the tail rotor shaft is matched with the pitch control shaft through an internal spline and an external spline, the booster control lever is connected with the pitch control shaft through a bearing and axially reciprocates along the internal spline of the tail rotor shaft under the axial reciprocating pushing of the booster control lever, so that the pitch of a tail rotor blade is changed, and the tail rotor pitch control shaft device adopts three-point support: the first support piece, the second support piece and the third support piece guarantee stable operation movement of the propeller pitch control shaft, reduce misalignment of the propeller pitch control shaft and the tail rotor booster control lever, relieve bending moment caused by unbalance loading, reduce abrasion or overheating faults of the propeller pitch control shaft and a bearing and the like, and improve stability and reliability of axial movement of the propeller pitch control shaft, so that the service life of the tail rotor propeller pitch control shaft device is prolonged.

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic view of a prior art tail rotor pitch control shaft;

FIG. 2 is a schematic view of a tail rotor pitch steering shaft arrangement of a preferred embodiment of the present invention;

FIG. 3 is a schematic view of a pitch steering shaft of the preferred embodiment of the present invention; and

FIG. 4 is a left side view of the pitch steering shaft of the preferred embodiment of the present invention.

The reference numbers illustrate:

1. a tail rotor shaft; 11. matching an internal spline; 2. a pitch control shaft; 21. guiding the external spline; 22. an installation part; 221. a groove structure; 222. a waist-shaped hole; 23. a flange edge structure; 231. bolt holes; 24. a mating surface; 3. a bearing; 31. a bearing bush; 32. a bearing seat; 4. a booster operating lever; 5. a first support member; 6. a second support member; 7. a third support member; 8. a snap ring; 9. a fork member.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

FIG. 1 is a schematic view of a prior art tail rotor pitch control shaft; FIG. 2 is a schematic view of a tail rotor pitch steering shaft arrangement of a preferred embodiment of the present invention; FIG. 3 is a schematic view of a pitch steering shaft of the preferred embodiment of the present invention; FIG. 4 is a left side view of the pitch steering shaft of the preferred embodiment of the present invention.

As shown in fig. 2 and 3, the tail rotor pitch steering shaft device of the present embodiment includes: the propeller pitch control device comprises a tail rotor shaft 1, a pitch control shaft 2, a booster control lever 4 and a support assembly, wherein the tail rotor shaft 1 is used for being matched and connected with an inner spline 11 of the tail rotor shaft 1 and reciprocating along the axial direction of the inner spline 11 of the tail rotor shaft 1 to realize pitch control of a propeller tail blade, the pitch control shaft 2 is provided with a guide outer spline 21 used for being matched with the inner spline 11 of the tail rotor shaft 1, the booster control lever 4 is arranged at a first free end of the pitch control shaft 2 and is in transmission connection with the pitch control shaft 2 through a bearing 3, the support assembly is used for supporting the pitch control shaft 2 to axially control reciprocating motion, and comprises a first support piece 5, a second support piece 6 and a third support piece 7; the first support 5 comprises a first sliding sleeve sleeved on the guide external spline 21; the second supporting piece 6 comprises a second sliding sleeve and a square ring, wherein the second sliding sleeve and the square ring are sleeved at one end, far away from the booster operating rod 4, of the propeller pitch operating shaft 2; the third support 7 comprises a piston seal intended to cooperate with the internal bore of the reducer case and to be mounted on the bearing bush 31 of the bearing 3. The invention relates to a tail rotor pitch control shaft device, which comprises a tail rotor shaft 1, a pitch control shaft 2 and a booster control lever 4, wherein the tail rotor shaft 1 is matched with the pitch control shaft 2 through an internal spline and an external spline, the booster control lever 4 is connected with the pitch control shaft 2 through a bearing 3, and axially reciprocates along an internal spline 11 of the tail rotor shaft 1 under the axial reciprocating pushing of the booster control lever 4, so that the pitch of a tail rotor blade is changed, and the tail rotor pitch control shaft device adopts three-point support: the first support piece 5, the second support piece 6 and the third support piece 7 ensure that the propeller pitch control shaft 2 can stably perform control motion, the misalignment between the propeller pitch control shaft 2 and the tail rotor booster control lever 4 is reduced, bending moment caused by unbalance loading is relieved, the faults of abrasion or overheating of the propeller pitch control shaft 2 and the bearing 3 are reduced, the stability and reliability of axial motion of the propeller pitch control shaft 2 are improved, and the service life of the tail rotor propeller pitch control shaft device is prolonged. The first support piece 5 adopts a first sliding sleeve, the second support piece 6 adopts a second sliding sleeve and a square ring, and the inner ring surfaces of the first sliding sleeve and the second sliding sleeve are both suitable working surfaces for operating and sliding the propeller pitch control shaft 2, so that the good support effect is achieved, and meanwhile, the axial reciprocating motion of the propeller pitch control shaft 2 is not hindered. The second support piece 6 is also provided with a square ring, the overall wear resistance of the second sliding sleeve can be increased, and the square ring is convenient to replace and low in cost. The third supporting piece 7 is a piston sealing ring which is assembled in a groove of a bearing bush 31 on the bearing 3 and is matched with an inner hole of a casing of the speed reducer, the bearing 3 and the pitch control shaft 2 perform control reciprocating motion, and the piston sealing ring also performs reciprocating motion with the bearing 3.

As shown in fig. 2, 3 and 4, in the present embodiment, the pitch control shaft 2 is a hollow cylindrical structure, and a first end of the pitch control shaft 2 is provided with a mounting portion 22 for mounting and positioning the pitch control shaft 2 and the bearing 3. The installation part 22 is circumferentially provided with a bearing nut for tightly matching the pitch control shaft 2 with the bearing 3, the booster control lever 4 is provided with the bearing 3 and a bearing seat 32, the bearing 3 is clamped between the bearing seat 32 and the pitch control shaft 2, and the bearing 3 and the bearing seat 32 are inserted into the first end of the pitch control shaft 2 and fixed at the position of the bearing nut so as to realize the installation and positioning of the pitch control shaft 2 and the bearing 3. A groove structure 221 for observing the assembly condition of the pitch control shaft 2 and the bearing 3 is arranged at the central hole of the mounting part 22. The outer surface of the mounting part 22 is provided with a kidney-shaped hole 222 for axial stopping of the pitch control shaft 2 and the bearing 3, and the clamping ring 8 is arranged at the end part of the pitch control shaft 2 and used for clamping and matching with the kidney-shaped hole 222 when the pitch control shaft 2 is assembled. The pitch control shaft 2 is provided with a mounting portion 22 at the end connected to the bearing 3, and the mounting portion 22 comprises an annular flange extending radially at the end surface of the pitch control shaft 2 in a hollow cylindrical shape, so that the bearing 3 and the pitch control shaft 2 are mounted in place, i.e. the booster lever 4 is in driving connection with the pitch control shaft 2. The central hole formed by the annular flange is provided with a groove structure 221 and a kidney-shaped hole 222 so as to be convenient for observing whether the nut and the snap ring 8 are installed in place. Specifically, the bearing 3, the bearing bush 31 and the bearing seat 32 are installed into a whole, then the bearing 32 is close to an inner ring at one end of the pitch control shaft, the end face of the pitch control shaft is tightly pressed with the inner ring, the bearing nut is connected with the bearing seat 32 and is stopped by the snap ring 8, meanwhile, the bearing 3 is close to an outer ring at one end of the booster control shaft, the end face of the booster control shaft is tightly pressed with the booster control shaft, the Suluke nut is locked with the bearing bush 32, and therefore the end of the pitch control shaft is connected with the end of the booster control shaft. The pitch control shaft 2 and the bearing 3 are installed in place by abutting the bearing nut against the installation part 22, and the contact area between the pitch control shaft 2 and the installation part of the bearing 3 is increased, so that the connection stability is increased. The mounting part 22 at the end face of the pitch control shaft 2 is further provided with a kidney-shaped hole 222, and the snap ring 8 is arranged in the kidney-shaped hole 222, so that an axial stopping effect is achieved, the friction loss between the pitch control shaft 2 and the bearing 3 is reduced, and the overall operation stability is maintained.

Preferably, two waist-shaped holes 222 are adopted, and the two waist-shaped holes 222 are symmetrically arranged on the outer surface of the mounting portion 22. Four groove structures 221 are adopted, and the four groove structures 221 are circumferentially arranged at intervals along the central hole of the mounting portion 22. The number of the above-mentioned components is determined so as to satisfy the operational stability of the entire tail rotor pitch control shaft device. More preferably, the bearing 3 is a double row angular contact ball bearing.

As shown in fig. 3, in this embodiment the second end of the pitch control shaft 2 is provided with a flange structure 23, and the flange structure 23 is provided with bolt holes 231 for bolting with the fork 9 for placing bolts from the second end of the pitch control shaft 2 into the interior. The bolt holes 231 are arranged in multiple groups, and the multiple groups of bolt holes 231 are circumferentially arranged at intervals along the flange edge structure 23. Each group of bolt holes 231 is a plurality of bolt holes 231 arranged at equal intervals. The end, away from the booster operating rod 4, of the pitch control shaft 2 is provided with a flange edge structure 23, and a bolt hole 231 is distributed in the flange edge structure 23 and is connected with the fork-shaped part 9 in a matched mode through a bolt. Compared with the connection by adopting a semicircular key or a nut in the prior art, the threaded hole formed in the flange edge structure 23 connects the pitch control shaft 2 with the fork-shaped part 9 through a bolt, so that the contact area of the connection part is increased, the connection is firmer, and the fretting wear of the connection part is reduced. Meanwhile, the fork-shaped part 9 can adopt a split structure, is convenient to disassemble and assemble when used in an external field, improves the maintainability of the tail rotor pitch control shaft device, and is particularly suitable for a hub integrated tail rotor shaft structure. The tail rotor shaft 1 is also provided with 3 horn holes, and the fork-shaped parts 9 are led out from the 3 horn holes, so that the overall length of the propeller pitch control shaft 2 is greatly reduced and the weight of the propeller pitch control shaft 2 is reduced in the overall design of the tail rotor pitch control shaft device.

In this embodiment, the pitch control shaft 2 is made of an aluminum alloy material. And/or the first supporting piece 5 is prepared from a graphite material; and/or the second support 6 is made of graphite material. And/or the third supporting piece 7 is prepared by adopting polytetrafluoroethylene as an outer layer and a steel spring as a wrapping inner layer. The existing propeller pitch control shaft 2 is made of steel materials, so that the overall strength of the propeller pitch control shaft 2 is guaranteed, and serious abrasion in the process of controlling reciprocating motion is prevented, but the propeller pitch control shaft 2 made of the existing steel materials is heavier in quality, and an oil storage mechanism needs to be additionally designed, so that the structure is complex, and the processing difficulty is increased. The aluminum alloy material is adopted to replace a steel part, and the weight reduction can reach 60-70%. According to the tail rotor pitch control shaft device, the pitch control shaft 2 made of the aluminum alloy material is applied to the tail rotor pitch control shaft device through the optimization of the whole structure and the combination of the three-point support design, so that the weight of the tail rotor pitch control shaft device is greatly reduced. The pitch control shaft 2 is made of aluminum alloy, the weight of the pitch control shaft is about 1.1kg, and the weight of the pitch control shaft is reduced by about 2kg compared with that of the pitch control shaft made of steel. Above-mentioned third support piece 7 is piston seal, and piston seal mainly constitutes: the outer layer is made of polytetrafluoroethylene material and wraps the steel spring of the inner layer. By adopting a double-layer structure, on one hand, the piston sealing ring has better wear resistance when sliding; on the other hand, when the bearing is supported, the rigidity of the bearing is weaker than that of the first support part 5 and the second support part 6, so that the supporting load is more distributed to the other two support parts, the load transmitted to the bearing 3 is reduced, the abrasion of the bearing 3 is reduced, and the service life of the bearing 3 is prolonged.

According to another aspect of the present invention, as shown in fig. 3, there is also provided a method for preparing a tail rotor pitch steering shaft device, which obtains the above-mentioned tail rotor pitch steering shaft device, and comprises the following steps: the outer surface of the guide male spline 21 is subjected to electroless nickel plating. And a matching surface 24 which is arranged on the propeller pitch control shaft 2 and is contacted with the second sliding sleeve and the square ring is sprayed with chromium oxide. In order to further increase the hardness and the wear resistance of the pitch control shaft 2 made of an aluminum alloy material, the outer surface of the guide external spline 21 is subjected to chemical nickel plating treatment to provide the overall hardness and the wear resistance of the pitch control shaft 2, and the guide external spline 21 is positioned in the tail reducer due to the optimized design of the tail rotor pitch control shaft device, so that the requirement on corrosion resistance is not high. Moreover, for aviation products, the requirements of surface roughness and dimensional accuracy required by the aviation products can be met by subsequent grinding, the guide external splines 21 on the pitch control shaft 2 are limited by the subsequent grinding, and the problems can be explained by adopting chemical nickel plating treatment. The matching surface 24 which is contacted with the second sliding sleeve and the square ring is sprayed with chromium oxide for hardening treatment so as to improve the wear resistance of the matching surface 24, and the matching surface 24 has a part which exposes the tail speed reducer, so that higher corrosion resistance is required.

In this embodiment, the method includes the following steps: the chemical nickel plating treatment comprises the following specific steps:

a. pretreatment: carrying out chemical degreasing, corrosion, nitric acid brightening and zinc dipping on a to-be-plated base body of the aluminum alloy, and protecting a non-plated surface;

b. alkaline chemical nickel preplating: carrying out chemical pre-nickel plating on the pretreated matrix to be plated by adopting an alkaline pre-plating solution to obtain a pre-plated part, wherein the pH value of the alkaline pre-plating solution is 8.5-9.2, the temperature of the chemical pre-nickel plating is 24-40 ℃, and the time is 4-10 min;

c. chemical nickel plating: chemical nickel plating is carried out on the pre-plated piece by adopting chemical plating solution, the pH value of the chemical plating solution is 4.4-5, the temperature of the chemical nickel plating is 85-92 ℃, and the deposition rate of the chemical nickel plating is 8-12 mu m/h;

d. and (3) heat treatment: and (3) carrying out heat treatment on the finished product after the chemical plating, wherein the heat treatment temperature is 150-170 ℃, the heat treatment time is 10-12 h, and cooling to finish the chemical nickel plating treatment.

Different from common metal nickel plating, the chemical nickel plating process has the advantages that the aluminum alloy material belongs to a difficult-to-plate base material, and the problems of poor plating layer binding force, poor covering quality and the like exist, so that a plating solution with high hardness requirement and high phosphorus content is required to be adopted for the plating solution. Secondly, the nickel plating process is more demanding, and the surface of the aluminum alloy substrate needs a pretreatment process which can be too fine.

The chemical nickel plating treatment step comprises:

a. the pretreatment comprises the following specific steps: the non-plated surface is first coated with a protective film. (1) Chemical oil removal: removing oil stains on the surface of the aluminum alloy base material by using a chemical reagent, wherein the chemical reagent mainly comprises 30-70 g/L sodium phosphate, 30-50 g/L sodium carbonate and 5-10 g/L sodium silicate, and the chemical oil removal temperature is 60-90 ℃ until the aluminum alloy base material is completely removed. The sodium phosphate has an emulsifying effect, the sodium carbonate has certain alkalinity and a buffering effect, so that the solution keeps alkalinity, the sodium silicate has a certain saponification effect, and the chemical reagent reduces the surface tension between oil stain and deoiling liquid to achieve the oil removing effect. (2) And (3) corrosion: the method adopts alkali corrosion, wherein the alkali liquor mainly comprises 40 g/L-60 g/L sodium hydroxide and 40 g/L-50 g/L sodium fluoride, the main formula is sodium hydroxide (40-60) g/L and sodium fluoride (40-50) g/L, the alkali corrosion temperature is generally 60-90 ℃, and the alkali corrosion time is 20-60 s, so as to remove a surface passivation layer, such as aluminum oxide. (3) Nitric acid light emission: the concentration of the adopted nitric acid solution is 50-80%, the temperature is room temperature, and the time is 5-10 s. The nitric acid has the function of neutralizing alkaline substances on the surface, inhibiting the rate of regenerating an oxide film, and removing gray substances and firmer black films which do not participate in alkaline reaction but are still adsorbed on the surface loosely during alkaline corrosion. (4) Zinc dipping: after dirt on the surface of the aluminum alloy base material is removed, the first zinc dipping, the zinc removing and the second zinc dipping are carried out, the zinc dipping solution adopts a formula produced by Chongqing Haodao company, the main salt brand is LD-5908A, the concentration is 200 ml/L-350 ml/L, the temperature is 10 ℃ to 30 ℃, and the time is 15 s-100 s. The purpose of zinc deposition is to deposit a thin layer of zinc on the surface of an aluminum alloy matrix through a displacement reaction between the aluminum alloy matrix and zinc ions in a zinc deposition solution, so that the surface activity of the matrix is reduced, and the surface of the aluminum alloy matrix is prevented from being re-oxidized. Meanwhile, the zinc film layer can reduce the potential difference between the aluminum alloy substrate and the pre-plated nickel layer, enhance the binding force between the substrate and the nickel plating layer, improve the surface hardness, the dimensional accuracy and the binding force of the part, and realize accurate and controllable plating layer thickness.

b. Alkaline chemical nickel preplating: and carrying out chemical nickel preplating on the pretreated substrate to be plated by adopting an alkaline pre-plating solution, wherein the alkaline pre-plating solution is a plating solution produced by Chongqing Standao company, the main salt brand is LD-5420A, the concentration is 35-60 ml/L, the pH value of the alkaline pre-plating solution is 8.5-9.2, the temperature of the chemical nickel preplating is 24-40 ℃, and the time is 4-10 min. The aluminum alloy is formed into thin compact nickel through alkaline chemical nickel pre-plating, and then the next nickel plating is carried out, so that the binding force and the corrosion resistance of the plating layer are improved.

c. Chemical nickel plating: chemical nickel plating is carried out on the pre-plated piece by adopting chemical plating solution, the chemical plating solution is produced by Chongqing Haidao company, the main salt brand is LD-5904A, the concentration is 40 ml/L-60 ml/L, the pH value of the chemical plating solution is 4.4-5, the temperature of the chemical nickel plating is 85-92 ℃, and the deposition rate of the chemical nickel plating is 8-12 mu m/h. The treatment time is determined according to the requirement of the thickness of the nickel layer.

d. And (3) heat treatment: and (3) carrying out heat treatment on the finished product subjected to chemical plating in a drying oven at the temperature of 150-170 ℃ for 10-12 h, and cooling in an air cooling mode to finish the chemical nickel plating treatment.

In this embodiment, the step of spraying chromium oxide includes: chromium oxide powder is sprayed on the matching surface 24 of the pitch control shaft 2 through a plasma spraying device, the temperature of the matching surface 24 is controlled to be lower than 160 ℃ in the spraying process, and grinding is carried out to form a chromium oxide coating. The plasma jet equipment mainly comprises a copper anode and a tungsten cathode, and both the copper anode and the tungsten cathode are cooled in a water cooling mode. The gas flows around the cathode and through the anode, being ionized by the arc generated between the two electrodes. The mechanical compression effect of the plasma promotes the energy to be gathered at the outlet of the nozzle, the gas has extremely high temperature under the action of electric energy and molecular energy, the speed is set to be 700-1000 m/s according to the type and the speed of the gas flow, the temperature can reach 15000-20000 ℃, and a proper amount of chromium oxide powder is melted and accelerated by the high-temperature plasma gas and then sprayed on the surface of the matching surface 24. The process material of the plasma spraying chromium oxide coating is chromium oxide powder, and the chromium oxide is ceramic with excellent chemical stability and has the characteristics of high hardness, wear resistance and corrosion resistance. In addition, the chromium oxide has a low friction coefficient, so that the chromium oxide coating can keep the friction coefficient and the abrasion loss small even under the high-temperature dry friction condition, and is suitable for controlling the reciprocating sliding of the pitch control shaft 2 to reduce the abrasion of the pitch control shaft 2. Also, during the spraying operation, the temperature of the faying surface 24 must be controlled to maintain the texture of the aluminum alloy material, with the maximum temperature of the aluminum alloy generally not exceeding 160 ℃. The surface roughness of the coating after plasma spraying is Ra 4-7, and Ra is less than 0.2 after grinding. The thickness of the coating after plasma spraying is 0.20 mm-0.30 mm; grinding to 0.07 mm-0.15 mm; porosity < 5% microscopic region. The appearance of the chromium oxide coating is uniform and consistent, and the chromium oxide coating does not peel off; there should be no separation of the coating during grinding, no cracks or grinding burns.

In this embodiment, the design of the defect tolerance and the test of the defect tolerance of the pitch control shaft 2 are also included. Defects are inevitably generated in the processes of production, manufacturing, assembly, transportation, use and maintenance of parts, and the influence of the possibly generated defects on the use of the parts must be considered in the design process, so that the maintainability of the product is improved. In order to improve the service life and the economy of the part, through the defect tolerance design and the defect tolerance test, the part can be continuously used as long as the defect does not expand during the inspection interval period even if the part has the defect, and the part is prevented from being retired in advance. When designing the defect tolerance of the part, firstly, the surface of the part is preset with defects: salt spray corrosion, scratches, craters, etc., and then strength test verifications were performed until the part developed cracks that could be inspected and the time the test was run was recorded. According to the test time, the inspection period of the part can be determined, namely the inspection period is actually determined to be less than the test time, if the inspection period is short, for example, less than a set repair interval requirement, the structure of the part needs to be optimized, and after the optimization, the defect tolerance test verification is continuously carried out, and the steps are iterated until the use requirement of the tail rotor pitch control shaft device is met. The pitch control shaft determines the inspection period of the pitch control shaft by using defect tolerance design and defect tolerance test, and greatly improves the maintainability and the economical efficiency of products.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.