CN120249599B

CN120249599B - High-strength bolt heat treatment process for wind power blade

Info

Publication number: CN120249599B
Application number: CN202510506570.6A
Authority: CN
Inventors: 黄久远
Original assignee: Guangdong Yongji Intelligent Manufacturing Co ltd
Current assignee: Guangdong Yongji Intelligent Manufacturing Co ltd
Priority date: 2025-04-22
Filing date: 2025-04-22
Publication date: 2025-09-26
Anticipated expiration: 2045-04-22
Also published as: CN120249599A

Abstract

The invention relates to the technical field of bolt heat treatment, in particular to a high-strength bolt heat treatment process for a wind power blade, which comprises the following steps of presetting a bolt heat treatment state, and performing impact treatment on the root of a bolt thread through a bolt heat treatment device to form a nanocrystalline layer; and carrying out three-stage pulse nitriding in an ammonia atmosphere containing Ce-La mixed rare earth, and carrying out gradient cooling by adopting water-based atomized quenching liquid containing polyvinyl alcohol and graphene under the action of a transverse steady magnetic field. The method has the beneficial effects that the comprehensive performance of the high-strength bolt of the wind power blade is remarkably improved through the multi-step synergistic effect of surface mechanical nanocrystallization pretreatment, rare earth element gradient nitriding, magnetic field auxiliary gradient quenching, pulse current cryogenic composite tempering and the like. The concrete is that the surface hardness is greatly improved, meanwhile, the good toughness of the core part is maintained, the corrosion resistance and the fatigue life of the bolt are also obviously improved, and the service life of the bolt in an extreme marine environment is longer.

Description

High-strength bolt heat treatment process for wind power blade

Technical Field

The invention relates to the technical field of bolt heat treatment, in particular to a high-strength bolt heat treatment process for a wind power blade.

Background

In the field of fans, special fasteners for fans, such as high-strength bolts for wind power blades, are of critical importance. In order to improve the performance of such bolts, a heat treatment process becomes a key link. The traditional heat treatment process has certain limitations in improving the strength, the wear resistance and the like of the bolts. Along with the increasing complexity of the running environment of the fan, the requirement on the performance of the bolts is continuously improved, and the development of a novel and efficient high-strength bolt heat treatment process for the wind power blade is urgent, so that the requirement of long-term stable running of the fan is met.

Currently, conventional heat treatment processes face challenges in improving bolt performance, such as matching of surface hardness and core toughness, uniformity of nitriding depth and hardness, cracking risk during quenching, and limitation of tempering treatment on performance improvement. Particularly, in an extreme marine environment, the bolt needs to bear severe working conditions such as high salt spray corrosion, alternating load and the like, and higher requirements are put on the strength, corrosion resistance and fatigue life of the bolt.

Therefore, a novel and efficient high-strength bolt heat treatment process for wind power blades is developed to solve the performance bottleneck problem in the prior art, and becomes the technical problem to be solved urgently at present

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a high-strength bolt heat treatment process for wind power blades, which is used for realizing the higher requirements on the strength, corrosion resistance and fatigue life of bolts under severe working conditions such as high salt spray corrosion, alternating load and the like of the bolts in an extreme marine environment.

The technical scheme for solving the technical problems is as follows, and the high-strength bolt heat treatment process for the wind power blade comprises the following steps:

presetting a bolt heat treatment state, and performing impact treatment on the root of a bolt thread through a bolt heat treatment device to form a nanocrystalline layer;

Carrying out three-stage pulse nitriding in an ammonia atmosphere containing Ce-La mixed rare earth;

Under the action of a transverse steady magnetic field, carrying out gradient cooling by adopting water-based atomized quenching liquid containing polyvinyl alcohol and graphene;

liquid nitrogen cryogenic treatment is performed, followed by a pulsed current applied during tempering.

Further, the temperature at the first stage of the three-stage pulse nitriding is 520 ℃, the nitriding time is 2h, the temperature at the second stage of the three-stage pulse nitriding is 580 ℃, the nitriding time is 1.5h, the temperature at the third stage of the three-stage pulse nitriding is 500 ℃, and the nitriding time is 3h.

Further, the transverse steady magnetic field intensity is regulated and controlled in stages, and the transverse steady magnetic field intensity comprises an initial stage, a main quenching stage and a final cooling stage, and the atomization pressure of the quenching liquid and the transverse steady magnetic field intensity are synchronously regulated and controlled in each stage.

Further, the liquid nitrogen cryogenic treatment comprises a first stage, a second stage and a third stage of gradient cooling;

The first stage is that the temperature is reduced from 25 ℃ to-80 ℃ at the speed of 3 ℃ per minute and maintained for 15 minutes;

the second stage is that the temperature is reduced from-80 ℃ to-140 ℃ at a temperature reduction rate of 2 ℃ per minute, and the temperature is kept for 10 minutes;

The third stage is that the temperature is reduced from-140 ℃ to-196 ℃ at a temperature reduction rate of 1 ℃ per minute and maintained for 5 minutes.

Further, the bolt heat treatment device comprises a fixing frame, a rotary station frame capable of rotating by 90 degrees periodically is rotatably arranged on the fixing frame, four bolt fixing components are arranged on the rotary station frame, a vibration support capable of moving up and down is connected to the bolt fixing components in a transmission mode, a transmission bottom shaft is rotatably arranged on the inner wall of the vibration support, a magnetic suction shaft is rotatably arranged on the inner wall of the transmission bottom shaft, a magnetic suction groove for magnetic suction positioning of a bolt is formed in the top of the magnetic suction shaft, the transmission bottom shaft and the magnetic suction shaft are coaxially and reversely rotated, an upper material loading station, a lower material loading station, a nanometer processing station, a negative pressure cleaning station and a cleaning station are sequentially arranged on the fixing frame in a clockwise direction, a spray pipe mechanism is arranged at the position on the fixing frame, corresponding to the nanometer processing station, the negative pressure cleaning station and the cleaning station, nanometer impact treatment is carried out on the bolts at the nanometer processing station, and negative pressure suction removal and low temperature stress elimination of the bolts are carried out at the cleaning station.

Further, the automatic screw machine comprises a servo motor arranged at the bottom of the fixing frame, an incomplete gear is arranged at the output shaft end of the servo motor, a transmission tooth surface is fixedly arranged on the incomplete gear, an intermittent shaft is arranged on the bottom surface of the rotary station frame, an intermittent gear meshed with the transmission tooth surface is fixedly arranged on the intermittent shaft, the meshing area of the transmission tooth surface corresponds to a central angle of 90 degrees, the radius of the incomplete gear is identical to that of the intermittent gear, a hollow tooth shaft is rotatably sleeved on the intermittent shaft, a driving gear ring is arranged on the hollow tooth shaft, a belt is connected between the output shaft end of the servo motor and the hollow tooth shaft in a transmission mode, a bottom cylinder is fixedly arranged on the fixing frame, a shaft bracket is fixedly arranged on the bottom cylinder, a transmission bevel gear and a driven gear in transmission connection with the driving gear are respectively arranged on the guide shaft at positions corresponding to the nanometer processing station, the negative pressure cleaning station and the cleaning station, the bolt fixing part is in adaptive connection with the transmission bevel gear, a screw rod is vertically arranged on the fixing frame, and the screw rod is connected with the lifting module.

Further, the bolt fixing component comprises a large circular shaft and a hollow shaft which are rotatably connected to the rotary station frame, one end of the large circular shaft is fixedly provided with a driven bevel gear meshed with the driving bevel gear, the hollow shaft and the large circular shaft are respectively provided with a first bevel gear, the two first bevel gears are meshed with each other, the hollow groove with two ends open and in sliding connection with the magnetic suction shaft is fixedly formed in the hollow shaft, the cross sections of the magnetic suction shaft and the hollow groove are regular hexagons, the large circular shaft is provided with an eccentric wheel, a follower wheel is rotatably arranged on the vibration support, the follower wheel is in rolling contact with the profile surface of the eccentric wheel, the vibration support is in sliding connection with the rotary station frame, and the top surface of the vibration support is provided with a vibration spring limited by the rotary station frame.

Further, the bolt fixing part further comprises a small circular shaft rotatably arranged on the vibration support, a conical tooth is arranged on the small circular shaft, a second conical tooth is arranged on the magnetic attraction shaft and the transmission bottom shaft, the two second conical teeth are in transmission connection with the conical teeth, and the two second conical teeth are respectively arranged on two sides of the conical tooth.

Further, spray tube mechanism includes pipe and follow-up seat, pipe fixed mounting is on handling the frame, two T shape guide arms are installed to the top surface of follow-up seat, two T shape guide arms all with pipe sliding connection, the inner wall of follow-up seat rotates and installs a spiral protection tube, the bottom fixed mounting who revolves protection tube has the sealed gum ring of being connected with the transmission lower shaft, the inner wall fixed mounting who revolves protection tube has a shower nozzle, the shower nozzle is oriented the bolt thread root with 45 inclination, a logical chamber has been offered to the top fixed of revolving protection tube, the tail end and the logical chamber intercommunication of shower nozzle, the bottom of pipe is through bellows and logical chamber rotation intercommunication, the cover is equipped with a follow-up spring on the bellows, the top fixed of pipe is provided with the nanometer material takeover with high pressure nanoparticle send into the device intercommunication in the nanometer processing station, the top fixed negative pressure of pipe is provided with the negative pressure with in the negative pressure cleaning station and is connected with the suction remover, the top fixed of washing liquid in the washing station is provided with the washing joint with send into the device intercommunication, the outside in the cleaning station of a spiral protection tube is fixed to be provided with a heating coil.

Further, still including rotating the sleeve of cover on locating the end section of thick bamboo, the fixed dirt absorbing runner that has seted up in inside of magnetic attraction axle, dirt absorbing runner's bottom is through going out dirty pipe and sleeve intercommunication, set up on the magnetic attraction axle be circumference array distribution and with dirt absorbing runner intercommunication's dirt absorbing hole, a blowdown chamber has been seted up to the fixed inside of end section of thick bamboo, a blowdown hole with blowdown chamber intercommunication has been seted up to the fixed position that just corresponds the cleaning station on the end section of thick bamboo, fixed mounting has the dirt accumulation case with blowdown chamber intercommunication on the mount.

Further, the magnetic attraction shaft is made of permanent magnetic materials, and the cross section of the magnetic attraction groove is regular hexagon.

The beneficial effects of the invention are as follows:

1. Through the multi-step synergistic effects of surface mechanical nanocrystallization pretreatment, rare earth element gradient nitriding, magnetic field assisted gradient quenching, pulse current cryogenic composite tempering and the like, the technical scheme remarkably improves the comprehensive performance of the high-strength bolt of the wind power blade. The concrete is that the surface hardness is greatly improved, meanwhile, the good toughness of the core part is maintained, the corrosion resistance and the fatigue life of the bolt are also obviously improved, and the service life of the bolt in an extreme marine environment is longer.

2. Based on the traditional heat treatment process, various innovations are carried out, such as forming a nanocrystalline layer by adopting tungsten carbide cobalt particles with the particle size of 100 mu m for impact treatment, introducing rare earth elements Ce-La for gradient nitriding, utilizing a steady magnetic field to assist gradient quenching, combining pulse current for cryogenic composite tempering and the like. The innovative processes not only improve the performance of the bolts, but also remarkably improve the production efficiency. The magnetic field assisted quenching realizes the gradient control of the cooling rate from the surface to the core by optimizing the magnetic field intensity and the quenching liquid injection speed, and avoids the cracking risk in the traditional quenching process. Meanwhile, the pulse current deep-cooling composite tempering technology further improves the strength and toughness of the bolt, so that the whole heat treatment process is more efficient and controllable.

3. According to the invention, the uniformity of the surface treatment of the bolt is remarkably improved, the shearing resistance and the fatigue life of the bolt are enhanced, a uniform nanocrystalline layer with the thickness of 50-80 mu m and the grain size of <100nm is formed at the root of the thread by combining high-frequency micro-amplitude vibration with tungsten carbide cobalt particle impact through a dynamic vibration regulation mechanism, compared with the traditional static impact, the grain refining efficiency is improved by 40%, the thickness deviation of the nanocrystalline layer is reduced from +/-15% to +/-5%, the problems of weak shearing resistance and short fatigue life caused by uneven particle distribution in the traditional process are solved, and the technology creatively introduces an eccentric wheel-follower vibration structure and regular hexagon magnetic attraction positioning, so that the bolt has no displacement deviation in the impact and is suitable for extreme wind load working conditions.

4. According to the invention, a three-stage pulse nitriding process is adopted, an ammonia atmosphere containing Ce-La rare earth is combined to form a rare earth element gradient permeation layer, compared with a single temperature nitriding process, the surface hardness uniformity is improved by 30%, the service life of a salt spray corrosion test is prolonged by more than 2 times, the salt spray corrosion test is remarkably adapted to the offshore high salt spray environment, the gradient design breaks through the temperature control bottleneck of the traditional nitriding process, and the deep diffusion of the rare earth element is promoted by dynamically adjusting the temperature, so that the dual advantages of high hardness and corrosion resistance are achieved.

5. According to the invention, under a transverse magnetic field of 0.5-1.2T, atomized quenching liquid containing graphene is adopted for gradient cooling, and the magnetic field intensity and cooling rate are dynamically adjusted through a machine learning model, so that residual stress fluctuation is reduced to be within +/-50 MPa from the conventional +/-150 MPa.

6. According to the invention, high-precision multi-station cooperation, production efficiency and consistency are improved, the positioning precision of the rotary station frame reaches +/-0.1 mm based on an incomplete gear intermittent gear structure driven by a servo motor, and the rotary station frame is matched with a regular hexagonal magnetic suction groove for clamping, so that circumferential sliding of bolts is thoroughly eliminated, compared with the traditional continuous rotary station, the multi-station switching efficiency is improved by 50%, the consistency of the thickness of a nano layer is improved to 98%, and the equipment design solves the industrial problems of large positioning deviation and unstable clamping of the traditional device through fusion of a mechanical structure and intelligent control, and provides reliable guarantee for batch production.

Drawings

FIG. 1 is a flow chart of a heat treatment process for high-strength bolts of wind power blades

FIG. 2 is a schematic diagram of a high-strength bolt heat treatment process for a wind turbine blade;

FIG. 3 is a schematic view of the overall structure of the bolt heat treatment apparatus of the present invention;

FIG. 4 is a schematic cross-sectional view of FIG. 1 according to the present invention;

FIG. 5 is a schematic view of a partial enlarged structure at A in FIG. 4 according to the present invention;

FIG. 6 is a schematic view of a partially enlarged structure of the present invention at B in FIG. 4;

FIG. 7 is a schematic view of a partially enlarged structure of the present invention at C in FIG. 4;

FIG. 8 is a schematic view of the structure of the negative pressure suction tube, the nano-material connection tube and the cleaning joint of the invention;

FIG. 9 is a schematic view of the structure of the bottom cartridge and intermittent gear of the present invention;

FIG. 10 is a schematic view of the structure of the axle housing and bottom cartridge of the present invention;

FIG. 11 is a schematic view of the structure of the magnetic attraction tank and the vibration shell of the invention.

In the drawings, the list of components represented by the various numbers is as follows:

1. The device comprises a bolt heat treatment device, 2, a fixed frame, 3, a rotary station frame, 4, a vibration bracket, 5, a transmission bottom shaft, 6, a magnetic attraction shaft, 7, a magnetic attraction groove, 8, a treatment frame, 9, a servo motor, 10, an incomplete gear, 11, an intermittent shaft, 12, an intermittent gear, 13, a hollow gear shaft, 14, a driving gear ring, 15, a bottom cylinder, 16, a shaft bracket, 17, a guide shaft, 18, a driven gear, 19, a screw lifting module, 20, a large round shaft, 21, a hollow shaft, 22, an eccentric wheel, 23, a follower wheel, 24, a vibration spring, 25, a small round shaft, 26, a follower seat, 27, a T-shaped guide rod, 28, a rotary protective cylinder, 29, a spray head, 30, a through cavity, 31, a corrugated pipe, 32, a follower spring, 33, a nano material connecting pipe, 34, a negative pressure suction pipe, 35, a cleaning joint, 36, a heating coil, 37, a sleeve, 38, a dirt suction runner, 39, a dirt suction hole, 40, a hollow shaft, 41, a dirt discharge hole, 42, a dirt box, 43, a dirt discharge box, a dirt discharge pipe, a guide pipe, 45 and a dirt discharge pipe.

Detailed Description

The principles and features of the present invention are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.

The present invention provides the following preferred embodiments

1-2, A high-strength bolt heat treatment process for a wind power blade comprises the following steps of:

SS01, surface mechanical nanocrystallization pretreatment, namely presetting a bolt 43 heat treatment state, wherein the bolt heat treatment device 1 adopts tungsten carbide cobalt particles with the particle size of 100 μm to perform impact treatment on the root of the thread of the bolt 43 at the speed of 300m/s to form a nanocrystalline layer with the thickness of 80 μm and the grain size of less than 100 nm;

SS02 and rare earth element gradient nitriding, namely three-stage pulse nitriding is carried out in an ammonia atmosphere containing 1.2wt% of Ce-La mixed rare earth;

The synergic catalysis mechanism of rare earth element (Ce-La) is as follows:

The surface activation is that the atomic radius of Ce (cerium) and La (lanthanum) rare earth elements is larger (Ce: 0.182nm, la:0.187 nm), the high surface energy characteristic can be preferentially adsorbed on the surface of the bolt, oxide films and impurities are removed, active sites are formed, and NH ₃ is promoted to be decomposed into active nitrogen atoms (N).

And the diffusion of the grain boundary is accelerated, rare earth elements are biased to the grain boundary in the nitriding process, the diffusion activation energy of nitrogen atoms is reduced, and the permeation of nitrogen to the matrix is accelerated. Experiments show that the nitrogen diffusion coefficient can be improved by 30-40% by adding 1.2wt% of Ce-La mixed rare earth.

Nitride refinement regulation, namely rare earth element inhibits coarsening of Fe ₃ N, promotes uniform precipitation of epsilon-Fe ₂₃ N phase, forms a fine nitride layer, and improves surface hardness (HV can reach 1200-1400) and corrosion resistance

In the step SS02, the temperature in the first stage of three-stage pulse nitriding is 520 ℃, the nitriding time is 2h, the temperature in the second stage of the three-stage pulse nitriding is 580 ℃, the nitriding time is 1.5h, the temperature in the third stage of the three-stage pulse nitriding is 500 ℃, and the nitriding time is 3h;

the three-section pulse type temperature gradient design is specifically as follows:

The first stage (520 ℃ C. X2 h) is that the medium temperature stage is mainly formed by gamma' -Fe ₄ N, rare earth elements are enriched on the surface, nano-level CeN/LaN particles are formed as nucleation points, and a high-hardness base layer (the thickness is about 10-15 mu m) is laid.

And the second stage (580 ℃ C. Multiplied by 1.5 h) is to heat to above austenitizing temperature to accelerate nitrogen to diffuse toward the core, and meanwhile, rare earth elements migrate inwards along the grain boundary to form a depth gradient transition layer (the total permeation layer reaches 0.3-0.4 mm) so as to relieve stress concentration caused by abrupt hardness change.

And the third section (500 ℃ multiplied by 3 h) is to stabilize epsilon phase in the cooling tempering stage, react rare earth elements with residual austenite to generate LaFeO ₃/Ce₂O₃ oxide film, seal micropores and improve salt spray corrosion resistance (ASTM B117 salt spray test life >1000 h).

The equipment is a controlled atmosphere pulse nitriding furnace (the purity of ammonia is more than or equal to 99.99 percent), and Ce-La mixed rare earth powder (Ce: la=3:1).

The ammonia atmosphere is NH ₃ flow 1.8L/min, mixed with Ce-La rare earth powder (200 meshes) 1.2wt%.

The temperature-time parameters are as follows:

The first stage is 520 ℃ multiplied by 2h, and the furnace pressure is 0.15MPa;

the second stage is that the temperature is 580 ℃ and the furnace pressure is 0.08MPa (periodic pulse is that 0.12MPa/0.05MPa is switched every 10 min);

And in the third stage, the temperature is 500 ℃ and the furnace pressure is 0.20MPa, and the time is 3 h.

The performance test results are as follows:

hardness gradient (HV 0.3):

Depth (mum)	0 (Surface)	50	100	200	300
						Hardness value	1320	980	750	620	450

The deep bias polymerization of Ce-La realizes the cross-scale performance matching of 'surface superhard-core tough', three-stage variable-temperature coupling pulse ammonia gas breaks through the diffusion dynamics limit of traditional isothermal nitriding, the permeation speed is improved by 40%, and the service life of the bolt in the offshore high-salt-fog environment is prolonged by more than 2 times due to the synergistic effect of the rare earth oxide film and the gradient nitriding layer.

SS03, magnetic field assisted gradient quenching, in which under the action of a transverse steady magnetic field of 1.2T, water-based atomized quenching liquid containing 20wt% of polyvinyl alcohol and 0.05wt% of graphene is adopted for gradient cooling;

The regulation mechanism of the transverse steady magnetic field is as follows:

Magnetostriction effect is that a transverse magnetic field of 1.2T induces a ferromagnetic material (such as 42CrMo steel) to generate anisotropic strain (delta L/L is approximately equal to 5 multiplied by 10 ^-6), so that the austenitic lattice is preferentially oriented along the magnetic field direction, and the martensitic transformation resistance is reduced.

Lorentz force inhibits bubbles, in the process of atomizing the quenching liquid, lorentz force (F=qv×B) generated by a magnetic field causes charged fog drops to generate precession motion, breaks a steam film, and improves a heat exchange coefficient (3800W/m ² K, which is 40% higher than that of the traditional water quenching).

Dislocation orientation arrangement, namely dislocation lines under a magnetic field are preferentially arranged along a {110} crystal face sliding system to form a substructure parallel to the direction of the magnetic field, and the shearing strength is improved (tau_max is improved by 18% -22%).

The characteristics of the graphene reinforced quenching liquid comprise:

0.05wt% of graphene improves the heat conductivity coefficient of quenching liquid from 0.6W/m.K to 1.8W/m.K (improving by 200%), and graphene sheets are aligned under a magnetic field (XRD shows (002) plane orientation degree > 85%), so that a rapid heat conduction channel is formed.

The wettability is optimized, namely graphene is adsorbed on the surface of a steel piece, the contact angle is reduced from 78 degrees to 32 degrees, the critical temperature of the Leidenfrost effect (from 280 ℃ to 450 ℃) is broken through, and the rapid transition from stable film boiling to nucleate boiling is realized.

Stress buffering, namely forming a three-dimensional network structure by polyvinyl alcohol (20wt%) and graphene, inhibiting the abrupt change of viscosity of the quenching liquid (eta=12 mPa.s at 25 ℃ and eta=3.2 mPa.s at 300 ℃) and reducing the concentration of thermal stress.

Dynamic control of gradient cooling includes:

Magnetic field-cooling coupling by increasing the spray speed of the quenching liquid from 2m/s to 5m/s through a magnetic field intensity gradient of 0.5T to 1.2T (0.1T is increased every 30 s), and realizing a cooling rate gradient from surface to core (surface: 220 ℃ per s, core: 45 ℃ per s).

And (3) regulating the phase change time sequence, namely forming lath martensite (the lath width is 50-80 nm) on the surface preferentially, keeping 10-15% of residual austenite in the core, and obtaining a hard-surface, heart-tough tissue (surface hardness HRC58-60, core impact energy AKU=75J).

The equipment comprises a transverse magnetic field quenching furnace (the magnetic field intensity is 0-2T adjustable) and a graphene modified atomized quenching system.

Magnetic field procedure:

The initial stage (0-30 s) is that a 0.5T steady magnetic field;

a main quenching stage (30-90 s) of linearly lifting to 1.2T;

the final cooling stage (90-120 s) is kept at 1.2T.

Parameters of quenching liquid:

polyvinyl alcohol concentration 20wt% (molecular weight 130,000);

Graphene content 0.05wt% (sheet diameter 5-10 μm, layer number < 5);

the atomization pressure is 0.4-0.8 MPa gradient pressurization.

It should be noted that, the synergistic effect of the 1.2T transverse magnetic field and the graphene quenching liquid improves the heat exchange efficiency to 2.3 times of the traditional oil quenching, avoids the high cracking risk of water quenching, and improves the fatigue life.

The method is suitable for mass production of wind power main shaft bolts, and service life is prolonged from 8 years to 15 years under the extreme working condition of a fan (alternating load + -250 kN and frequency 0.5 Hz), and intermediate maintenance and replacement are not needed.

SS04, pulse current cryogenic composite tempering, namely, firstly carrying out liquid nitrogen cryogenic treatment for-196 ℃ multiplied by 2h, and then applying pulse current of 1000A/cm ² and 10kHz in the tempering process at 450 ℃ for 4h;

The equipment comprises a liquid nitrogen cryogenic box (-196 ℃ C.+/-2 ℃ C.) and a high-frequency pulse tempering furnace (maximum current density 1500A/cm ²).

And (3) deep cooling treatment:

the temperature is-196 ℃;

time 2h (comprising 30min step cooling: 25 ℃ C. Fwdarw.80 ℃ C. Fwdarw.140 ℃ C. Fwdarw.196 ℃ C.).

The first stage, 25 ℃ to-80 ℃ and the cooling rate is 3 ℃ per min, and the temperature is kept for 15min;

and in the third stage, the temperature is reduced by-140 ℃ to-196 ℃ at the rate of 1 ℃ per minute, and the temperature is kept for 5 minutes.

Microcracks caused by quenching (crack density is reduced from 15 bars/cm ² to less than or equal to 2 bars/cm ² of the traditional process) are inhibited by three-stage gradient cooling (total time is 30 min).

Pulse tempering:

Temperature 450 ℃ (furnace temperature uniformity ± 5 ℃);

current parameter 1000A/cm ², 10kHz square wave pulse (50 μs pulse width, 450 μs interval);

time 4h (2 cycles, 30min air cooling every 2 h).

The strength and toughness of the wind power bolt are improved through the space-time cooperation of the deep cooling and the pulse current, so that the service life of the wind power bolt is longer in an extreme marine environment.

The invention relates to a high-strength bolt heat treatment process for a wind power blade, which comprises the following steps of:

SS05, real-time process regulation and control, namely dynamically regulating the magnetic field intensity and cooling rate of the SS03 step through a machine learning model to control the fluctuation of the surface residual stress within +/-50 MPa;

The problem of uneven residual stress distribution caused by parameter fixation in the traditional heat treatment process is solved by dynamically adjusting the magnetic field strength and the cooling rate through a machine learning model, in a specific work flow, the system collects temperature gradient, magnetic field strength and cooling fluid flow data in a quenching stage in real time, and combines the material characteristics of the bolts 43, and the surface residual stress fluctuation is strictly controlled within +/-50 MPa through the trained neural network prediction optimal parameter combination.

The inventor also finds that in the heat treatment process of the high-strength bolt of the wind power blade, the uniformity of the surface treatment is poor, and in the traditional mechanical impact treatment method, due to the lack of a dynamic vibration regulation mechanism, the nano particles are unevenly distributed, so that the consistency of the thickness of a nano crystal layer and the size of crystal grains is poor, and the shearing resistance and the fatigue life of the root of the bolt thread are affected.

As shown in fig. 3-11, the invention also designs a bolt heat treatment device 1 for realizing impact treatment on the root of the screw thread of the bolt.

The invention relates to a bolt heat treatment device 1, which comprises a fixed frame 2, wherein a rotary station frame 3 capable of periodically rotating by 90 degrees is rotatably arranged on the fixed frame 2, four bolt fixing parts are arranged on the rotary station frame 3, a vibration support 4 capable of moving up and down is connected to the bolt fixing parts in a transmission way, a transmission bottom shaft 5 is rotatably arranged on the inner wall of the vibration support 4, a magnetic suction shaft 6 is rotatably arranged on the inner wall of the transmission bottom shaft 5, a magnetic suction groove 7 for magnetic suction positioning of a bolt 43 is formed in the top of the magnetic suction shaft 6, and the transmission bottom shaft 5 and the magnetic suction shaft 6 coaxially and reversely rotate;

The magnetic suction shaft 6 is made of permanent magnetic materials, and the cross section of the magnetic suction groove 7 is regular hexagon.

The regular hexagonal magnetic attraction groove 7 is precisely matched with the hexagonal structure of the head of the bolt 43, zero clearance positioning is achieved, in the working flow, the magnetic attraction shaft 6 made of permanent magnetic materials is used for quickly fixing the bolt 43 through magnetic force, the regular hexagonal section of the hollow groove is matched, the bolt 43 is prevented from sliding circumferentially in the processing process, compared with a round or square groove, the design clamping efficiency is improved by 60%, the standard wind power bolt 43 specification is adapted, the thickness deviation of the thread root nanometer layer caused by clamping looseness is avoided, and the process stability in mass production is ensured;

The fixing frame 2 is sequentially provided with a loading and unloading station, a nano treatment station, a negative pressure cleaning station and a cleaning station along the clockwise direction, the fixing frame 2 is provided with a treatment frame 8 in a lifting manner, the positions of the treatment frame 8, which correspond to the nano treatment station, the negative pressure cleaning station and the cleaning station, are respectively provided with a spray pipe mechanism, the bolts 43 perform nano impact treatment on the nano treatment station, the negative pressure suction of nano particles is performed on the negative pressure cleaning station, and the cleaning and low-temperature stress elimination of the bolts 43 are performed on the cleaning station.

The automatic cleaning device is characterized by further comprising a servo motor 9 arranged at the bottom of the fixed frame 2, an incomplete gear 10 is arranged at the output shaft end of the servo motor 9, a transmission tooth surface is fixedly arranged on the incomplete gear 10, an intermittent shaft 11 is arranged on the bottom surface of the rotary station frame 3, an intermittent gear 12 meshed with the transmission tooth surface is fixedly arranged on the intermittent shaft 11, the corresponding central angle of the meshing area of the transmission tooth surface is 90 degrees, the radius of the incomplete gear 10 is the same as that of the intermittent gear 12, a hollow tooth shaft 13 is rotatably sleeved on the intermittent shaft 11, a driving gear ring 14 is arranged on the hollow tooth shaft 13, a belt is connected between the output shaft end of the servo motor 9 and the hollow tooth shaft 13 in a transmission manner, a bottom cylinder 15 is fixedly arranged on the fixed frame 2, a shaft bracket 16 is fixedly arranged on the bottom cylinder 15, a guide shaft 17 is rotatably arranged at positions corresponding to the nano-processing station, the negative pressure cleaning station and the cleaning station, a driven gear 18 is respectively arranged on the guide shaft 17, a vertical lifting screw rod 19 is in a transmission connection with the driving gear ring 14 in a matched manner, and a lifting screw rod 19 is arranged on the fixed frame 2, and a processing module is connected with the screw rod 8.

When the wind power blade high-strength bolt 43 heat treatment equipment runs, the servo motor 9 is started, the hollow gear shaft 13 is driven to rotate through a belt, the driving gear ring 14 on the hollow gear shaft 13 rotates along with the hollow gear shaft 13, the driving gear ring 14 and the driven gear 18 are mutually matched to drive the guide shaft 17 to rotate, meanwhile, the incomplete gear 10 at the output shaft end of the servo motor 9 is meshed with the intermittent gear 12, as the corresponding central angle of the meshing area of the transmission tooth surface is 90 degrees, and the radius of the incomplete gear 10 is the same as that of the intermittent gear 12, the precise periodic 90-degree rotation of the rotary station frame 3 is realized, seamless switching of nano treatment, cleaning and cleaning stations is ensured, the screw rod lifting module 19 carries out precise lifting on the treatment frame 8, and the traditional rotary station frame 3 always causes positioning deviation due to mechanical gaps, so that the continuity and accuracy of a heat treatment process are influenced.

The bolt fixing part comprises a large circular shaft 20 and a hollow shaft 21 which are rotatably connected to the rotary station frame 3, a driven bevel gear meshed with the driving bevel gear is fixedly arranged at one end of the large circular shaft 20, first bevel gears are respectively arranged on the hollow shaft 21 and the large circular shaft 20, the two first bevel gears are mutually meshed, hollow grooves with two ends open and in sliding connection with the magnetic attraction shaft 6 are fixedly formed in the hollow shaft 21, the cross sections of the magnetic attraction shaft 6 and the hollow grooves are regular hexagons, an eccentric wheel 22 is arranged on the large circular shaft 20, a follower wheel 23 is rotatably arranged on the vibration support 4, the follower wheel 23 is in rolling contact with the outline surface of the eccentric wheel 22, the vibration support 4 is in sliding connection with the rotary station frame 3, and a vibration spring 24 limited by the rotary station frame 3 is arranged on the top surface of the vibration support 4.

When carrying out surface mechanical nanocrystallization pretreatment to wind power blade high strength bolt 43, big circular shaft 20 rotates under the external power drive, the driven bevel gear and the transmission bevel gear meshing of its one end, and then drive big circular shaft 20 rotation, eccentric wheel 22 on the big circular shaft 20 rotates along with it, eccentric wheel 22 promotes follower 23, make vibration support 4 slide along rotatory station frame 3, vibration spring 24 plays elastic reset effect, realize the high frequency slight vibration of bolt 43 in the nanometer impact treatment, hollow shaft 21 and the first bevel gear intermesh on the big circular shaft 20, and hollow shaft 21 inside hollow groove and magnetic attraction axle 6 sliding connection, the cross section of magnetic attraction axle 6 and hollow groove is regular hexagon, bolt 43 clamping stability has been strengthened, particle uneven distribution in the tradition static impact, influence the homogeneity on nanocrystalline layer, this structure is through the rolling contact of eccentric wheel 22 and follower 23 and the elastic reset of vibration spring 24, make bolt 43 screw thread root and tungsten carbide cobalt particle fully contact, nanocrystalline layer forms more evenly, grain refining efficiency promotes 40%, displacement deviation in the processing simultaneously, wind power blade 43 has guaranteed that wind power performance under the extreme stability is reached under the wind power, the extreme performance of wind power 43 is reached, and the service life-span is improved.

The bolt fixing part further comprises a small circular shaft 25 rotatably arranged on the vibration support 4, a conical tooth is arranged on the small circular shaft 25, a second conical tooth is arranged on the magnetic attraction shaft 6 and the transmission bottom shaft 5, the two second conical teeth are in transmission connection with the conical tooth, and the two second conical teeth are respectively arranged on two sides of the conical tooth.

The conical teeth on the small round shaft 25 are meshed with the magnetic suction shaft 6 and the second conical teeth of the transmission bottom shaft 5, so that coaxial reverse rotation of the transmission bottom shaft 5 and the magnetic suction shaft 6 is realized, in a working flow, the magnetic suction shaft 6 drives the bolt 43 to rotate, meanwhile, the transmission bottom shaft 5 reversely drives the rotary protection cylinder 28 in the spray pipe mechanism to rotate, the spray head 29 always precisely covers the thread root part at a 45-degree inclination angle when the rotary protection cylinder 28 rotates, the covering uniformity of nano particles at the thread root part of the bolt 43 can be effectively improved through coaxial reverse rotation arrangement of the spray head 29 and the bolt 43 during nano treatment, the overflow rate of the nano particles can be effectively reduced through arrangement of the protection cylinder, the safety during nano treatment operation is further improved, the residual rate of non-nano particles at the thread root part of the bolt 43 and the inner wall of the protection cylinder can be effectively reduced through arrangement of the protection cylinder and the vibration structure during the treatment of the bolt 43, and the inner wall cleanliness of the protection cylinder is effectively improved.

The spray pipe mechanism comprises a guide pipe 45 and a follow-up seat 26, the guide pipe 45 is fixedly arranged on the treatment frame 8, two T-shaped guide rods 27 are arranged on the top surface of the follow-up seat 26, the two T-shaped guide rods 27 are in sliding connection with the guide pipe 45, a rotary protection cylinder 28 is rotatably arranged on the inner wall of the follow-up seat 26, a sealing rubber ring connected with the transmission bottom shaft 5 is fixedly arranged at the bottom end of the rotary protection cylinder 28, a spray head 29 is fixedly arranged on the inner wall of the rotary protection cylinder 28, the spray head 29 faces the root of a screw thread of a bolt 43 at a 45-degree inclination angle, a through cavity 30 is fixedly arranged at the top of the rotary protection cylinder 28, the tail end of the spray head 29 is communicated with the through cavity 30, the bottom end of the guide pipe 45 is rotatably communicated with the through a corrugated pipe 31, and a vibration following spring 32 is sleeved on the corrugated pipe 31.

In the work flow, the rotary protection cylinder 28 is connected with the transmission bottom shaft 5 through a sealing glue ring, the corrugated pipe 31 compensates lifting displacement under the buffer of the vibration spring 32, finally, the rotary protection cylinder 28 generates driven vibration rotation along with the vibration rotation motion of the transmission bottom shaft 5, and the sealing property of the joint of the transmission bottom shaft 5 and the rotary protection cylinder 28 can be effectively ensured through the setting of the sealing glue ring.

The top end of the guide pipe 45 in the nano treatment station is fixedly provided with a nano material connecting pipe 33 communicated with the high-pressure nano particle feeding device, the top end of the guide pipe 45 in the negative pressure cleaning station is fixedly provided with a negative pressure suction pipe 34 communicated with the negative pressure suction device, the top end of the guide pipe 45 in the cleaning station is fixedly provided with a cleaning joint 35 communicated with the cleaning liquid feeding device, and the outside of the rotary protection cylinder 28 in the cleaning station is fixedly provided with a heating coil 36.

In different stations of the high-strength bolt 43 heat treatment of the wind power blade, the spray pipe mechanism plays an important role, in the nano treatment station, high-pressure nano particles enter the guide pipe 45 through the nano material connecting pipe 33, then enter the through cavity 30 at the top end of the rotary protection cylinder 28 through the corrugated pipe 31, finally spray out from the spray head 29 facing the thread root of the bolt 43 at a 45-degree inclined angle, impact treatment is carried out on the thread root of the bolt 43, at this moment, the follow-up seat 26 can slide on the guide pipe 45 through the T-shaped guide rod 27, the distance between the spray head 29 and the bolt 43 is adjusted, the rotary protection cylinder 28 can rotate, the spray head 29 can better cover the thread root of the bolt 43, in the negative pressure cleaning station, the negative pressure suction pipe 34 is connected with the negative pressure suction device, residual nano particles after nano treatment are sucked out, in the cleaning station, cleaning liquid enters through the cleaning joint 35, the spray head 29 sprays cleaning liquid to clean the bolt 43, the heating coil 36 outside the rotary protection cylinder 28 of the cleaning station can heat the cleaning liquid, the cleaning liquid is improved, the traditional spray pipe mechanism is difficult to accurately treat and clean the thread root of the bolt 43, and has a single function, the design of the spray pipe mechanism can be ingenious, different realization of different functions, the accurate treatment of the thread root of the bolt 43 can be realized, the accurate, the high-strength of the wind power blade is improved, the high-strength performance of the whole wind power blade is ensured, and the high-strength, the whole performance of the wind power blade is ensured, and high quality, can be better realized, and improved, and the performance, and the quality and improved

When the wind power blade high-strength bolt 43 heat treatment equipment is operated, the nano material connecting pipe 33 is communicated with the high-pressure nano particle feeding device, tungsten carbide cobalt particles with the particle size of 50-100 mu m can be stably conveyed to the spray head 29 at the speed of 200-300m/s, the root of the thread of the bolt 43 is subjected to impact treatment to form a high-quality nano crystal layer, the negative pressure suction pipe 34 is communicated with the negative pressure absorber in the negative pressure cleaning station, residual nano particles after the nano treatment are timely and effectively absorbed, the influence of the particles on the subsequent process is avoided, the cleaning joint 35 is communicated with the cleaning liquid feeding device in the cleaning station, sufficient cleaning liquid is provided for cleaning the bolt 43, and the heating coil 36 outside the rotary protective cylinder 28 can perform low-temperature thermal stress elimination on the processed bolt 43 after the cleaning is finished.

The high-pressure nanoparticle feeding device can adopt a Sulzer Metco spraying system or a Praxair powder feeding device, and is selected or replaced according to actual conditions, and redundant description is omitted here.

Still including rotating sleeve 37 that the cover was located on the end section of thick bamboo 15, the fixed dirt absorbing runner 38 that has offered in inside of magnetic attraction axle 6, dirt absorbing runner 38's bottom is through going out dirty pipe 44 and sleeve 37 intercommunication, set up on the magnetic attraction axle 6 be the circumference array distribution and with dirt absorbing runner 38 intercommunication the dirt absorbing hole 39 of a set of, a blowdown chamber 40 has been offered to the fixed interior of end section of thick bamboo 15, a blowdown hole 41 with blowdown chamber 40 intercommunication of having offered on the end section of thick bamboo 15 and the fixed position that corresponds the cleaning station, fixed mounting has the dirt accumulation case 42 with blowdown chamber 40 intercommunication on the mount 2.

The dirt sucking hole 39 in the magnetic sucking shaft 6 is communicated with the dirt discharging cavity 40 of the bottom cylinder 15, so that the cleaning waste liquid is directionally collected.

The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

1. A heat treatment process for high-strength bolts of wind turbine blades, characterized by comprising the following steps:

The bolt heat treatment state is preset, and the bolt thread root is subjected to impact treatment by the bolt heat treatment device to form a nanocrystalline layer;

Three-stage pulse nitriding is carried out in an ammonia atmosphere containing Ce-La mixed rare earth;

Under the action of a transverse steady magnetic field, gradient cooling is performed using a water-based atomized quenching liquid containing polyvinyl alcohol and graphene.

Liquid nitrogen cryogenic treatment is performed, followed by pulsed current applied during the tempering process.

2. A heat treatment process for high-strength bolts for wind turbine blades according to claim 1, characterized in that the temperature of the first stage of the three-stage pulse nitriding process is 520°C and the nitriding time is 2 hours, the temperature of the second stage is 580°C and the nitriding time is 1.5 hours, and the temperature of the third stage is 500°C and the nitriding time is 3 hours.

3. A heat treatment process for high-strength bolts for wind turbine blades according to claim 1, characterized in that the intensity of the transverse steady-state magnetic field is regulated in stages, including an initial stage, a main quenching stage, and a final cooling stage; the atomization pressure of the quenching liquid is synchronously regulated with the intensity of the transverse steady-state magnetic field in each stage.

4. A heat treatment process for high-strength bolts for wind turbine blades according to claim 1, characterized in that the liquid nitrogen cryogenic treatment comprises a first stage, a second stage, and a third stage of gradient cooling;

The first stage: 25°C to -80°C, cooling rate 3°C/min, hold for 15 minutes;

The second stage: -80°C to -140°C, cooling rate 2°C/min, hold for 10 minutes;

The third stage: -140°C to -196°C, cooling rate 1°C/min, holding for 5 minutes.

5. A heat treatment process for high-strength bolts of wind turbine blades according to any one of claims 1 to 4, characterized in that the bolt heat treatment device comprises a fixed frame (2), a rotating workstation (3) that can periodically rotate 90° is rotatably mounted on the fixed frame (2), the rotating workstation (3) is provided with four bolt fixing components, a vibration bracket (4) that can move up and down is connected to the bolt fixing components, a transmission bottom shaft (5) is rotatably mounted on the inner wall of the vibration bracket (4), and the inner wall of the transmission bottom shaft (5) is provided with a rotation axis. A magnetic shaft (6) is rotatably mounted, and a magnetic groove (7) for magnetically positioning a bolt (43) is provided on the top of the magnetic shaft (6). The transmission bottom shaft (5) rotates coaxially with the magnetic shaft (6) in opposite directions. The fixed frame (2) is provided with loading and unloading stations, a nano-processing station, a negative pressure cleaning station, and a cleaning station in a clockwise direction. A processing frame (8) is movably mounted on the fixed frame (2). A nozzle mechanism is provided on the processing frame (8) at positions corresponding to the nano-processing station, the negative pressure cleaning station, and the cleaning station.

6. A heat treatment process for high-strength bolts of wind turbine blades according to claim 5, characterized in that it also includes a servo motor (9) installed at the bottom of the fixed frame (2), an incomplete gear (10) is installed on the output shaft end of the servo motor (9), and a transmission tooth surface is fixedly provided on the incomplete gear (10), an intermittent shaft (11) is installed on the bottom surface of the rotating work station (3), an intermittent gear (12) meshing with the transmission tooth surface is fixedly installed on the intermittent shaft (11), the meshing area of the transmission tooth surface corresponds to a central angle of 90°, the radius of the incomplete gear (10) is the same as the radius of the intermittent gear (12), a hollow gear shaft (13) is rotatably sleeved on the intermittent shaft (11), and the hollow gear shaft (13) A driving gear ring (14) is installed on the servo motor (9), and a belt is connected to the output shaft end of the servo motor (9) and the hollow gear shaft (13). A bottom cylinder (15) is fixedly installed on the fixed frame (2), and a shaft frame (16) is fixedly installed on the bottom cylinder (15). A guide shaft (17) is rotatably installed on the shaft frame (16) and corresponding to the positions of the nano-processing station, the negative pressure cleaning station and the cleaning station. The guide shaft (17) is respectively installed with a transmission bevel gear and a passive gear (18) connected to the driving gear ring (14). The bolt fixing component is adapted to be connected to the transmission bevel gear. A vertically arranged screw lifting module (19) is installed on the fixed frame (2), and the screw lifting module (19) is connected to the processing frame (8).

7. A heat treatment process for high-strength bolts for wind turbine blades according to claim 6, characterized in that the bolt fixing component comprises a large circular shaft (20) and a hollow shaft (21) rotatably connected to a rotating work station frame (3), one end of the large circular shaft (20) is fixedly mounted with a passive bevel gear meshing with a transmission bevel gear, a first bevel gear is mounted on both the hollow shaft (21) and the large circular shaft (20), the two first bevel gears mesh with each other, the interior of the hollow shaft (21) is fixedly opened with openings at both ends and A hollow groove is slidably connected to the magnetic shaft (6), and the cross-sections of the magnetic shaft (6) and the hollow groove are both regular hexagons. An eccentric wheel (22) is installed on the large circular shaft (20), and a follower wheel (23) is rotatably installed on the vibration bracket (4). The follower wheel (23) is in rolling contact with the contour surface of the eccentric wheel (22). The vibration bracket (4) is slidably connected to the rotating work station (3), and a vibration spring (24) is installed on the top surface of the vibration bracket (4) and is limited by the rotating work station (3).

8. A heat treatment process for high-strength bolts of wind turbine blades according to claim 7, characterized in that the bolt fixing component also includes a small circular shaft (25) rotatably mounted on the vibration bracket (4), a conical tooth is installed on the small circular shaft (25), and a second conical tooth is installed on each of the magnetic shaft (6) and the transmission bottom shaft (5), and the two second conical teeth are both connected to the conical tooth in a transmission manner, and the two second conical teeth are respectively arranged on both sides of the conical tooth.

9. A heat treatment process for high-strength bolts of wind turbine blades according to claim 6, characterized in that the nozzle mechanism comprises a guide tube (45) and a follower seat (26), the guide tube (45) is fixedly mounted on the processing frame (8), two T-shaped guide rods (27) are mounted on the top surface of the follower seat (26), and the two T-shaped guide rods (27) are both slidably connected to the guide tube (45), a rotary sleeve (28) is rotatably mounted on the inner wall of the follower seat (26), a sealing rubber ring connected to the transmission bottom shaft (5) is fixedly mounted on the bottom end of the rotary sleeve (28), a nozzle (29) is fixedly mounted on the inner wall of the rotary sleeve (28), the nozzle (29) is inclined at a 45° angle toward the thread root of the bolt (43), and the rotary sleeve (28) is fixedly mounted with a nozzle. A through cavity (30) is fixedly provided at the top, the tail end of the nozzle (29) is connected to the through cavity (30), the bottom end of the conduit (45) is rotatably connected to the through cavity (30) through a bellows (31), a vibration spring (32) is sleeved on the bellows (31), the top end of the conduit (45) in the nano-processing station is fixedly provided with a nano-material connecting pipe (33) connected to a high-pressure nano-particle feeding device, the top end of the conduit (45) in the negative pressure cleaning station is fixedly provided with a negative pressure suction pipe (34) connected to a negative pressure suction device, the top end of the conduit (45) in the cleaning station is fixedly provided with a cleaning joint (35) connected to a cleaning liquid feeding device, and a heating coil (36) is fixedly installed on the outside of the rotary casing (28) in the cleaning station.

10. A heat treatment process for high-strength bolts of wind turbine blades according to claim 7, characterized in that it also includes a sleeve (37) rotatably sleeved on the bottom cylinder (15), a sewage suction channel (38) is fixedly opened inside the magnetic shaft (6), and the bottom end of the sewage suction channel (38) is connected to the sleeve (37) through a sewage outlet pipe (44), a group of sewage suction holes (39) distributed in a circumferential array and connected to the sewage suction channel (38) are opened on the magnetic shaft (6), a sewage discharge cavity (40) is fixedly opened inside the bottom cylinder (15), a sewage discharge hole (41) connected to the sewage discharge cavity (40) is fixedly opened on the bottom cylinder (15) and corresponding to the position of the cleaning station, and a sewage storage box (42) connected to the sewage discharge cavity (40) is fixedly installed on the fixed frame (2).