CN112604838A

CN112604838A - Nozzle device and spray gun

Info

Publication number: CN112604838A
Application number: CN202011458538.9A
Authority: CN
Inventors: 李羿含; 姬迎风; 李星彤; 魏平; 徐建
Original assignee: Hubei Super Aviation Technology Co ltd
Current assignee: Hubei Super Aviation Technology Co ltd
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2021-04-06
Anticipated expiration: 2040-12-10
Also published as: CN112604838B

Abstract

The invention relates to the technical field of airplane landing gear beam fatigue crack repairing equipment, in particular to a nozzle device and a spray gun. The nozzle device comprises a Laval nozzle, wherein the Laval nozzle comprises a contraction cavity, a throat acceleration cavity and an expansion cavity which are sequentially communicated; the interior of the Laval nozzle is also provided with a partition part which equally divides the throat accelerating cavity into two sub-accelerating cavities, and the partition part is used for equally dividing a single air flow in the contraction cavity into two air flows which are respectively guided into the two sub-accelerating cavities for acceleration; the pipe wall of the Laval nozzle is provided with two powder inlets communicated with the expansion cavity. The invention has the beneficial effects that: the single-strand airflow can be uniformly divided into two airflows when passing through the dividing part and respectively introduced into the two sub-acceleration cavities of the throat acceleration cavity, the two metal powders are conveyed into the expansion cavity along with the two airflows and are accelerated and fully mixed through the two sections, and the accelerated and fully mixed metal powders impact the substrate to form a new coating.

Description

Nozzle device and spray gun

Technical Field

The invention relates to the technical field of airplane landing gear beam fatigue crack repairing equipment, in particular to a nozzle device and a spray gun.

Background

With the increase of combat training frequency and strength, the landing gear of a large number of active main combat types starts to generate fatigue cracks with different degrees, and once the fatigue cracks are generated, if the fatigue cracks are not processed in time, the service life of the landing gear is seriously influenced. Fatigue cracks are found in the landing gear beam when a certain type of airplane is overhauled, and the cold spraying technology is determined to be adopted to increase the material and prolong the service life for repairing through earlier research and demonstration.

The cold spraying equipment adopted at present preheats high-pressure carrier gas to a higher temperature by an electric heater, the carrier gas enters a Laval nozzle to be accelerated to form supersonic airflow, spraying powder is carried by powder conveying airflow and is axially injected into the nozzle, and then high-speed particles impact a substrate in a solid state to generate severe plastic deformation to form a coating due to the fact that the supersonic airflow in the nozzle is accelerated to a high speed.

In order to ensure that the strength of the repaired landing gear meets the standard, a metal coating generally needs to be prepared, the conventional method in the preparation process of the metal composite coating is to mechanically mix two or more kinds of powder according to a certain proportion and then put the mixture into a powder feeder, the particle size and density difference of the mixed powder particles are large, the uniform mixing is difficult to effectively mix, and the component proportion of the mixed powder added into a Laval nozzle through the powder feeder may deviate.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a nozzle device to solve the problem that the strength of a coating is influenced due to the poor mixing effect of powder prepared by a metal coating.

The technical scheme for solving the technical problems is as follows: a nozzle device comprises a Laval nozzle, wherein the Laval nozzle comprises a contraction cavity, a throat acceleration cavity and an expansion cavity which are sequentially communicated; the interior of the Laval nozzle is also provided with a partition part which equally divides the throat accelerating cavity into two sub-accelerating cavities, and the partition part is used for equally dividing a single air flow in the contraction cavity into two air flows which are respectively guided into the two sub-accelerating cavities for acceleration; the pipe wall of the Laval nozzle is provided with two powder inlets communicated with the expansion cavity, and the two powder inlets are respectively used for sending two kinds of powder into the accelerated two air flows and fully mixing the two kinds of powder in the expansion cavity.

Further, the two powder inlets are symmetrically arranged along the axis of the feeding direction of the Laval nozzle; the angle between the powder inlet and the axis is-degrees.

Furthermore, a sheath is arranged on the outer surface of the Laval nozzle at one end of the expansion cavity; a heat exchange channel spirally wound along the outer wall of the Laval nozzle is arranged in the sheath; the heat exchange channel comprises a liquid inlet and a liquid outlet which are arranged on the sheath.

Further, the laval nozzle and the partition are integrally formed.

Further, the section area of the contraction cavity gradually decreases from the feed inlet to the throat accelerating cavity; the section area of the expansion cavity gradually increases from the throat accelerating cavity to the discharge hole.

A spray gun comprises a heating device, a powder feeder and the nozzle device.

The invention has the beneficial effects that: this nozzle device will be through the preliminary acceleration of the single strand air current of shrink chamber through the heating, the single strand air current can evenly separate into two air currents and introduce respectively into two sub-acceleration intracavity in the acceleration chamber of throat when passing through the partition portion, two air currents move to the in-process in expansion chamber from the acceleration chamber of throat, two kinds of metal powder that will need mix are leading-in to two air currents through two powder inlets respectively, two kinds of metal powder are along with carrying along with two air currents and accelerating and intensive mixing through the two-stage process in the expansion chamber, thereby metal powder through accelerating and intensive mixing strikes the base plate and forms new coating.

Drawings

FIG. 1 is a schematic view showing an external structure of a nozzle device according to the present invention;

FIG. 2 is a cross-sectional view of a nozzle arrangement of the present invention;

fig. 3 is a schematic structural diagram of the second embodiment.

In the drawings, the components represented by the respective reference numerals are listed below:

1. the device comprises a Laval nozzle, 101, a contraction cavity, 102, a throat accelerating cavity, 103, an expansion cavity, 1a, a partition part, 1b, a powder inlet, 2, a sheath, 201, a heat exchange channel, 3, a heating device, 4 and a powder feeder.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

Landing gear is an attachment device for supporting an aircraft for ground (surface) movement during takeoff and landing or ground (surface) taxiing on the lower portion of the aircraft. The landing gear is the only part for supporting the whole airplane, so that the landing gear is an integral part of the airplane; without it, the aircraft cannot move on the ground. After the aircraft takes off, the landing gear may be retracted depending on flight performance. The landing gear device is an important part with force bearing and maneuverability of an aircraft, and plays an extremely important role in the safe taking-off and landing process of the aircraft, the landing gear beam (force bearing truss) at the upper part of the landing gear device is subjected to large alternating impact load in the taking-off and landing process of the aircraft, and once fatigue cracks occur, the flight safety is seriously threatened.

Cold spraying is a spray technique based entirely on the aerodynamic principle. The particles are low in heating temperature and still keep solid, and the solid particles are deposited on the surface of a workpiece through mechanical processes such as adiabatic shear instability caused plastic rheology or severe plastic deformation under the conditions of extremely high stress, strain and strain rate. Therefore, the particles are not easy to be oxidized, burnt, phase change, structure change and the like in the spraying process.

The residual stress of the coating is mainly compressive stress, the spraying efficiency is high, and thick coatings and even block materials can be prepared. Based on the characteristics, the technology has obvious advantages in the aspects of preparing and developing novel material coatings such as nano and amorphous material coatings and other heat-sensitive material coatings, and is low in energy consumption, recyclable in material resources and free of environmental pollution, thereby being a green spraying technology. Through the experiment, adopt the cold spraying mode of repairing to restore the tired line of aircraft landing gear roof beam, can effectively promote the structural strength and the surperficial integrality of landing gear roof beam, avoided the emergence life-span of the whole crackle of structure, promoted the fatigue life of landing gear roof beam base member to a large extent.

The spray pipe in the existing cold spraying equipment generally adopts a Laval spray pipe. The front half part of the nozzle is contracted from big to small to the middle to a narrow throat, and the narrow throat is expanded from small to big to the arrow bottom. The gas in the arrow body flows into the front half of the nozzle under high pressure, passes through the narrow throat and escapes from the rear half. The structure can change the speed of the airflow due to the change of the spray cross section area, so that the airflow is accelerated from subsonic speed to sonic speed to supersonic speed.

Example one

As shown in fig. 1 and 2, the nozzle device provided by the present invention comprises a laval nozzle 1, wherein the laval nozzle 1 comprises a contraction cavity 101, a throat acceleration cavity 102 and an expansion cavity 103 which are sequentially communicated, and the cross-sectional area of the contraction cavity 101 gradually decreases from a feed inlet to the throat acceleration cavity 102; the section area of the expansion cavity 103 gradually increases along the throat accelerating cavity 102 to the discharge hole; the interior of the laval nozzle 1 is further provided with a partition part 1a which equally divides the throat accelerating cavity 102 into two sub accelerating cavities, and the laval nozzle 1 and the partition part 1a are integrally formed.

The partition part 1a is used for equally dividing a single air flow in the contraction cavity 101 into two air flows which are respectively guided into the two sub-acceleration cavities for acceleration; the tube wall of the laval nozzle 1 is provided with two powder inlets 1b communicated with the expansion cavity 103, the powder inlets 1b are connected to a powder feeder, and the two powder inlets 1b are respectively used for feeding two kinds of powder into two accelerated air flows and fully mixing the two kinds of powder in the expansion cavity 103. This nozzle device will pass through contraction chamber 101 and tentatively accelerate through the single-stranded air current of heating, single-stranded air current can evenly divide into two air currents and introduce respectively into two sub-acceleration chambeies of throat acceleration chamber 102 when passing through partition portion 1a, two air currents move the in-process of expansion chamber 103 from throat acceleration chamber 102, two kinds of metal powder that will mix are leading-in to two air currents through two powder entrances 1b respectively, two kinds of metal powder are carried along with two air currents and are passed through two-stage process in the expansion chamber 103 and accelerate and the intensive mixing, thereby metal powder through accelerating and intensive mixing strikes the base plate and forms new coating.

In the present embodiment, the two powder inlets 1b are symmetrically arranged along the axis of the feeding direction of the laval nozzle 1; the angle between the powder inlet 1b and the axis is 60-90 degrees, which can ensure that the metal powder can be smoothly conveyed into the expansion cavity 103 along the powder inlet 1 b.

Research and development personnel show that in the improvement process of the cold spraying device, an important improvement direction is to improve the working gas, when the type of the working gas is determined, the temperature is the only factor capable of changing the speed, and the metal powder is accelerated along with the carrying and dragging of the airflow; however, for some metal powder with low melting point and softer, because the throat accelerating cavity 102 is narrower, the metal powder is easy to adhere in the throat accelerating cavity 102 of the laval nozzle 1, and the pipe blockage phenomenon can occur after long-time operation.

In order to further improve the problem of pipe blockage, the outer surface of the Laval nozzle 1 at one end of the expansion cavity 103 is also provided with a sheath 2; a heat exchange channel 201 spirally wound along the outer wall of the Laval nozzle 1 is formed in the sheath 2; heat transfer passageway 201 is including seting up inlet and the liquid outlet on sheath 2, the leading-in coolant liquid of inlet, and the coolant liquid through the heat transfer is discharged along the liquid outlet, carries out the heat transfer through the outside to Laval spray tube 1, effectively reduces the temperature of expanding the chamber 103 inner wall, avoids long-time working process, and the high temperature leads to metal powder to melt and the adhesion is expanding the chamber 103 inner wall in the expansion chamber 103, has reduced the risk of stifled pipe.

Example two

As shown in fig. 3, a spray gun comprises a heating device 3 and a powder feeder 4, and further comprises a nozzle device, wherein high-pressure airflow is heated through the heating device 3, the heated airflow is conveyed into the nozzle device, metal powder is conveyed into an expansion cavity 103 of the nozzle device through the powder feeder 4, the metal powder is accelerated and fully mixed and then sprayed to the surface of a base layer of an aircraft landing gear to be repaired, the sprayed landing gear coating has high bonding strength and can reach more than 100MPa, and the requirements of strong load and long service life in the fields of aviation, aerospace and the like can be completely met.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A nozzle device comprises a Laval nozzle (1), and is characterized in that the Laval nozzle (1) comprises a contraction cavity (101), a throat acceleration cavity (102) and an expansion cavity (103) which are sequentially communicated; the interior of the Laval nozzle (1) is also provided with a partition part (1a) which equally divides the throat accelerating cavity (102) into two sub-accelerating cavities, and the partition part (1a) is used for equally dividing a single air flow in the contraction cavity (101) into two air flows which are respectively led into the two sub-accelerating cavities for acceleration; the wall of the Laval nozzle (1) is provided with two powder inlets (1b) communicated with the expansion cavity (103), and the two powder inlets (1b) are respectively used for sending two kinds of powder into two accelerated air flows and fully mixing the two kinds of powder in the expansion cavity (103).

2. A nozzle device according to claim 1, characterized in that the two powder inlets (1b) are arranged symmetrically along the axis of the feed direction of the laval nozzle (1); the angle between the powder inlet (1b) and the axis is 60-90 degrees.

3. A nozzle device according to claim 1, characterized in that the outer surface of the laval nozzle (1) at the end of the expansion chamber (103) is further provided with a jacket (2); a heat exchange channel (201) spirally wound along the outer wall of the Laval nozzle (1) is arranged in the sheath (2); the heat exchange channel (201) comprises a liquid inlet and a liquid outlet which are arranged on the sheath (2).

4. A nozzle device according to claim 1, characterized in that the laval nozzle (1) is formed integrally with the partition (1 a).

5. A nozzle device according to claim 1, characterized in that the cross-sectional area of the converging chamber (101) decreases gradually from the inlet opening to the throat accelerating chamber (102); the cross-sectional area of the expansion cavity (103) gradually increases along the throat accelerating cavity (102) to the discharge hole.

6. A spray gun comprising heating means (3) and a powder feeder (4), characterized by further comprising a nozzle device according to any one of claims 1-5.