阅读说明：本技术 用于叶片表面选区制备涂层的夹具及涂层的制备方法 (Clamp for preparing coating on selected area of blade surface and preparation method of coating ) 是由 何光宇 张兆路 杨竹芳 陈皎 韩霄 于 2020-06-12 设计创作，主要内容包括：本发明公开了用于叶片表面选区制备涂层的夹具及涂层的制备方法,所述夹具包括叶片固定轴、盖板支架、上盖板和下盖板,叶片固定轴与盖板支架连接,上盖板安装在盖板支架的上端面上,下盖板安装在叶片固定轴的下端面上,且上盖板与下盖板的错位卡合连接；可以在发动机叶片或者涡轮叶片的喷涂硬质涂层时利用本夹具对叶片进行夹持和固定,利用分区镀膜工艺在叶片表面制备出满足冲蚀和疲劳性能要求的涂层,满足对发动机叶片或者涡轮叶片局部喷涂硬质涂层的要求,降低叶片表面的冲蚀损伤,并且保证其叶片的疲劳强度,本夹具具有结构简单、使用方便、设计合理的特点。(The invention discloses a fixture for preparing a coating on a selected area of the surface of a blade and a preparation method of the coating, wherein the fixture comprises a blade fixing shaft, a cover plate bracket, an upper cover plate and a lower cover plate; the fixture can be used for clamping and fixing the blade when the hard coating is sprayed on the engine blade or the turbine blade, the coating meeting the requirements of erosion and fatigue performance is prepared on the surface of the blade by using a partitioned coating process, the requirement of locally spraying the hard coating on the engine blade or the turbine blade is met, the erosion damage on the surface of the blade is reduced, and the fatigue strength of the blade is ensured.)

1. A anchor clamps that is used for blade surface selection district preparation coating, its characterized in that: the novel blade cover plate comprises a blade fixing shaft (1), a cover plate support (2), an upper cover plate (3) and a lower cover plate (4), wherein the blade fixing shaft (1) is connected with the cover plate support (2), the upper cover plate (3) is installed on the upper end face of the cover plate support (2), the lower cover plate (4) is installed on the lower end face of the blade fixing shaft (1), and the upper cover plate (3) is connected with the lower cover plate (4) in a staggered clamping mode.

2. The fixture for selective preparation of coatings on blade surfaces according to claim 1, characterized in that: the blade fixing shaft (1) comprises a flange plate (11), a connecting shaft (12) and a connector (13), the flange plate (11) is arranged at the left end of the blade fixing shaft, the connecting shaft (12) is arranged at the right end of the flange plate (11), and the flange plate (11) is connected with the connector (13) through the connecting shaft (12); connector (13) are the U-shaped structure, including tenon portion joint groove (131), joint arch (132), first threaded connection hole (133), second threaded connection hole (134) and third threaded connection hole (135), tenon portion joint groove (131) set up the centre in connector (13), it is spacing to blade tenon portion all to be provided with joint arch (132) at tenon portion joint groove (131) outside upper and lower both ends, and the symmetry is provided with second threaded connection hole (134) in the protruding symmetry of upper portion joint, the protruding symmetry of going up of lower part joint is provided with third threaded connection hole (135), first threaded connection hole (133) set up the symmetry on the connector lateral wall on tenon portion joint groove (131) upper portion, and run through the lateral wall.

3. The fixture for selective preparation of coatings on blade surfaces according to claim 2, characterized in that: the cover plate support (2) is of a U-shaped groove structure, a fourth threaded connecting hole (21) and a fifth threaded connecting hole (22) are respectively formed in the side walls of the U-shaped groove at the upper end and the lower end of the cover plate support (2), and the fifth threaded connecting hole (22) is matched with the first threaded connecting hole (133) for use.

4. The fixture for selective preparation of coatings on blade surfaces according to claim 3, characterized in that: upper cover plate (3) including last roof (31), go up left riser (32), go up left baffle (33), go up right riser (34), upper end cover (35) and last preceding baffle (36), go up roof (31) and be the roof of upper cover plate (3), go up left riser (32) and set up the left side at last roof (31), go up left baffle (33) and set up the front end left part at last roof (31), go up right riser (34) and set up the right side at last roof (31), upper end cover (35) are inverted triangle-shaped, set up the rear end at last roof (31), go up preceding baffle (36) and set up the front end at last roof (31), be connected with last left baffle (33).

5. The fixture for selective preparation of coatings on blade surfaces according to claim 4, characterized in that: the lower cover plate (4) comprises a lower bottom plate (41), a lower right vertical plate (42), a lower right baffle plate (43), a lower left vertical plate (44), a lower end cover (45) and a lower front baffle plate (46), wherein the lower bottom plate (41) is a bottom plate of the lower cover plate (4), the lower right vertical plate (42) is arranged on the right side of the lower bottom plate (41) and is in matched dislocation clamping with the upper right vertical plate (44), the lower right baffle plate (43) is arranged on the right side of the front end of the lower bottom plate (41) and is matched with the upper left baffle plate (33) for use, the blade fixing shaft (1) is limited, the lower left vertical plate (44) is arranged on the left side of the lower bottom plate (41) and is in matched dislocation clamping with the upper left vertical plate (32), the lower end cover plate (45) is triangular and is arranged at the rear end of the lower bottom plate (41), and the lower front baffle plate (46) is arranged at the front end of the lower bottom plate (41).

6. The fixture for selective preparation of coatings on blade surfaces according to claim 5, characterized in that: the upper top plate (31) is provided with a first fixing connecting hole (311) and a first sliding fixing groove (312), the first fixing connecting hole (311) is matched with the fourth threaded connecting hole (21) for use, the first sliding fixing groove (312) is matched with the fourth threaded connecting hole (21) and a hexagon bolt for use, and the cover plate bracket (2) is connected with the upper cover plate (3); and a second fixed connecting hole (411) and a second sliding fixing groove (412) are formed in the lower bottom plate (41), the second fixed connecting hole (411) is matched with the third threaded connecting hole (135) for use, and the second sliding fixing groove (412) is matched with the third threaded connecting hole (135) and the hexagon bolt for use.

7. The fixture for selective preparation of coatings on blade surfaces according to claim 5, characterized in that: and third sliding fixing grooves (341) are correspondingly arranged on the upper left vertical plate (32), the lower right vertical plate (42), the upper right vertical plate (34) and the lower left vertical plate (44), and the upper left vertical plate (32), the lower right vertical plate (42), the upper right vertical plate (34) and the lower left vertical plate (44) are fixed in a staggered manner.

8. The fixture for selective preparation of coatings on blade surfaces according to claim 5, characterized in that: the upper end cover (35) is provided with an arc-shaped groove (351) and a first blade limiting groove (352), the arc-shaped groove (351) is an inclined edge of an inverted triangle, and the first blade limiting groove (352) is arranged at the lower end of the arc-shaped groove (351); the lower end cover (45) is provided with an arc-shaped protrusion (451) and a second blade limiting groove (452), the arc-shaped protrusion (451) is a triangular bevel edge, and the second blade limiting groove (452) is arranged at the upper end of the arc-shaped protrusion (451); the arc-shaped groove (351) and the arc-shaped protrusion (451) are matched for use to form a clamping gap for clamping the front end part of the blade, and the radians of the arc-shaped groove (351) and the arc-shaped protrusion (451) are the same as the radians of the front end part of the blade; the first blade limiting groove (352) and the second blade limiting groove (452) are matched for use, and the upper side portion and the lower side portion of the front end portion of the clamping blade are clamped.

9. A method for producing a blade surface coating using the fixture option for producing a blade surface coating of claim 1, characterized in that: the method comprises the following steps:

s1, pretreatment: carrying out sand blasting treatment on a blade coating area by using 70-micron fine sand, respectively carrying out ultrasonic cleaning on the blade subjected to sand blasting for 2 times by using acetone and absolute ethyl alcohol, wherein each time is 15 minutes, and rapidly drying the blade by using high-purity nitrogen;

s2, connecting the blade fixing shaft with a cover plate support by using a hexagonal screw, clamping the blade tenon part processed in the step S1 in a tenon part clamping groove, and respectively installing an upper cover plate and a lower cover plate, wherein during installation, the relative positions of the fixing shaft, the upper cover plate and the lower cover plate are adjusted according to the position of a blade coating area, so that the blade coating area can be completely clamped outside a gap, and the blade fixing shaft is connected with a coating machine by using a bolt for coating;

s3, Ti ion implantation preparation, wherein before preparation, a coating machine is vacuumized to the vacuum degree of 1.0 × 10^-4-5.0×10^-3Pa, raising the temperature of the vacuum chamber to 400 ℃ -¹⁵-1.0×10¹⁶Ion/m²；

S4, preparing the titanium nitride coating, which comprises the following specific steps: (1) depositing a TiN coating on the surface of the Ti ion sputtering layer obtained by sputtering; (2) adjusting the bias voltage of the ion plating matrix to-350V, turning on a Ti target power supply, and introducing N₂The gas flow is 20-30sccm, and Ti ions and N generated by the Ti target₂After the gas reaction, depositing the gas on the surface of the interlayer to obtain a TiN deposited coating; (3) during deposition, the arcing current is 110-120mA, the magnetic filtering current is 2.0A, and the voltage is 24.2V; (4) depositing a TiN coating for 8 hours;

and S5, stopping arc, cooling, taking out the blade, and finishing the preparation of the coating without the gradual change coating on the surface of the blade.

10. The method for selective preparation of blade surface coatings according to claim 9, characterized in that: a preparation process of the transition layer can be further arranged between the step S3 and the step S5, and the specific process is as follows:

preparing a transition layer:

(1) sequentially adjusting the bias voltage of a substrate of the magnetic filtering ion injection composite coating machine to-800V, -600V and-400V, and respectively carrying out Ti ion sputtering under each bias voltage;

(2) opening the Ti target, setting the arcing current to be 110-120mA, the magnetic filtering current to be 3.0A and the voltage to be 24.2V;

(3) the sputtering time under the bias voltage of each matrix is 30-120 s;

(4) obtaining a Ti ion sputtering layer with the thickness of 150nm-600nm on the surface of the matrix injected with Ti ions;

and finishing the preparation of the coating with the gradient coating on the surface of the blade.

Technical Field

The invention belongs to the technical field of advanced manufacturing of aero-engines, and particularly relates to a clamp for preparing a coating on a selected area of a blade surface and a preparation method of the coating.

Background

In the process of flying, taking off and landing in desert areas, dust, sand and the like in the air can cause serious erosion to the blades of the engine, particularly to a certain area range at two sides of the blade tips under the action of high-speed airflow, and can cause the falling of the area near the blade tips when serious, thereby having larger influence on the performance of the engine in terms of structure; the hard coating is introduced to the surface of the blade, so that the erosion resistance of the blade can be remarkably improved, but the introduction of the hard coating can cause the reduction of the fatigue strength of the blade;

the test research and numerical simulation show that most of sand dust particles erode the blade near the blade tip, and the improvement of the erosion resistance of the blade, particularly the area near the blade tip, is particularly important, so that the coating is prepared on the area with serious erosion damage on the surface of the blade tip, the reduction of the fatigue strength of the coating on the blade is controlled on the premise of solving the problem of erosion of the sand dust on the specific area of the blade, and the method has important significance for improving the application of the hard coating on the aeroengine.

Disclosure of Invention

Aiming at the existing problems, the invention aims to provide a method and a fixture for preparing a coating on a selected area of the surface of a blade, which can clamp and fix the blade when a hard coating is sprayed on the engine blade or the turbine blade, and utilize a sectional coating process to prepare the coating meeting the requirements of erosion and fatigue performance on the surface of the blade, thereby meeting the requirements of locally spraying the hard coating on the engine blade or the turbine blade, reducing the erosion damage on the surface of the blade and ensuring the fatigue strength of the blade.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a anchor clamps for blade surface selective area preparation coating, including blade fixed axle, apron support, upper cover plate and lower apron, the blade fixed axle is connected with the apron support, and the upper cover plate is installed on the up end of apron support, and the lower apron is installed on the lower terminal surface of blade fixed axle, and the upper cover plate is connected with lower apron dislocation block.

Preferably, the blade fixing shaft comprises a flange plate, a connecting shaft and a connector, the flange plate is arranged at the left end of the blade fixing shaft, the connecting shaft is arranged at the right end of the flange plate, and the flange plate and the connector are connected through the connecting shaft; the connector is the U-shaped structure, including tenon portion joint groove, joint arch, first threaded connection hole, second threaded connection hole and third threaded connection hole, tenon portion joint groove sets up in the centre of connector, all is provided with the joint arch at tenon portion joint inslot portion's upper and lower both ends and carries on spacingly to the blade tenon portion, and the symmetry is provided with second threaded connection hole in the upper portion joint arch, and the symmetry is provided with third threaded connection hole in the lower part joint arch, first threaded connection hole sets up the symmetry on the connector lateral wall on tenon portion joint groove upper portion, and runs through the lateral wall.

Preferably, the cover plate support is of a U-shaped groove structure, a fourth threaded connecting hole and a fifth threaded connecting hole are formed in the side walls of the U-shaped groove at the upper end and the lower end of the cover plate support respectively, and the fifth threaded connecting hole is matched with the first threaded connecting hole for use.

Preferably, the upper cover plate include the roof, go up left riser, go up left baffle, go up right riser, upper end cover and last preceding baffle, go up the roof and be the roof of upper cover plate, go up left riser setting in the left side of last roof, go up left baffle setting in the front end left part of last roof, go up right riser setting on the right side of last roof, the upper end cover is inverted triangle-shaped, sets up the rear end at last roof, goes up preceding baffle setting in the front end of last roof, is connected with last left baffle.

Preferably, the lower cover plate comprises a lower bottom plate, a lower right vertical plate, a lower right baffle, a lower left vertical plate, a lower end cover and a lower front baffle, the lower bottom plate is a bottom plate of the lower cover plate, the lower right vertical plate is arranged on the right side of the lower bottom plate and is in matched staggered clamping with the upper right vertical plate, the lower right baffle is arranged on the right side of the front end of the lower bottom plate and is matched with the upper left baffle to be used for limiting the blade fixing shaft, the lower left vertical plate is arranged on the left side of the lower bottom plate and is in matched staggered clamping with the upper left vertical plate, the lower end cover is triangular and is arranged at the rear end of the lower bottom plate, and the lower front baffle is arranged at the front end of the lower bottom plate and is.

Preferably, the upper top plate is provided with a first fixed connecting hole and a first sliding fixing groove, the first fixed connecting hole is matched with the fourth threaded connecting hole for use, and the first sliding fixing groove is matched with the fourth threaded connecting hole and the hexagon bolt for use, so that the cover plate bracket is connected with the upper cover plate; and a second fixed connecting hole and a second sliding fixing groove are formed in the lower base plate, the second fixed connecting hole is matched with the third threaded connecting hole for use, and the second sliding fixing groove is matched with the third threaded connecting hole and the hexagon bolt for use.

Preferably, last left riser and right riser down, go up right riser and left riser down on all correspond and be provided with the third fixed slot that slides, carry out the dislocation to going up left riser and right riser down, going up right riser and left riser down and fixing.

Preferably, the upper end cover is provided with an arc-shaped groove and a first blade limiting groove, the arc-shaped groove is an inclined edge of an inverted triangle, and the first blade limiting groove is arranged at the lower end of the arc-shaped groove; the lower end cover is provided with an arc-shaped bulge and a second blade limiting groove, the arc-shaped bulge is a triangular bevel edge, and the second blade limiting groove is arranged at the upper end of the arc-shaped bulge; the arc-shaped groove and the arc-shaped bulge are matched for use to form a clamping gap for clamping the front end part of the blade, and the radians of the arc-shaped groove and the arc-shaped bulge are the same as the radian of the front end part of the blade; the first blade limiting groove and the second blade limiting groove are matched for use, and the upper side portion and the lower side portion of the front end portion of the clamping blade are clamped.

A method for producing a blade surface coating using a fixture option for producing a coating on a blade surface, comprising the steps of:

s1, pretreatment: carrying out sand blasting treatment on a blade coating area by using 70-micron fine sand, respectively carrying out ultrasonic cleaning on the substrate sample block subjected to sand blasting for 2 times by using acetone and absolute ethyl alcohol, each time for 15 minutes, and rapidly drying by using high-purity nitrogen;

s2, connecting the blade fixing shaft with a cover plate support by using a hexagonal screw, clamping the blade tenon part processed in the step S1 in a tenon part clamping groove, respectively installing an upper cover plate and a lower cover plate, adjusting the relative positions of the fixing shaft, the upper cover plate and the lower cover plate according to the position of a blade coating area during installation so that the blade coating area can be completely clamped outside a gap, and connecting the blade fixing shaft with a coating machine through a bolt for coating;

s3, Ti ion implantation preparation, wherein before preparation, a coating machine is vacuumized to the vacuum degree of 1.0 × 10^-4-5.0×10^{- 3}Pa, raising the temperature of the vacuum chamber to 400-¹⁵-1.0×10¹⁶Ion/m²；

S4, preparing the titanium nitride coating, which comprises the following specific steps: (1) depositing a TiN coating on the surface of the Ti ion sputtering layer obtained by sputtering; (2) adjusting the bias voltage of the ion plating matrix to-350V, turning on a Ti target power supply, and introducing N₂The gas flow is 20-30sccm, and Ti ions and N generated by the Ti target₂After the gas reaction, depositing the gas on the surface of the transition layer to obtain a TiN deposition coating; (3) during deposition, the arcing current is 110-120mA, the magnetic filtering current is 2.0A, and the voltage is 24.2V; (4) depositing a TiN coating for 8 hours;

and S5, stopping arc, cooling, taking out the blade, and finishing the preparation of the coating without the gradual change coating on the surface of the blade.

Preferably, a preparation process of the transition layer may be further provided between the step S3 and the step S5, and the specific process is as follows:

preparing a transition layer:

(1) sequentially adjusting the bias voltage of a substrate of the magnetic filtering ion injection composite coating machine to-800V, -600V and-400V, and respectively carrying out Ti ion sputtering under each bias voltage;

(2) opening the Ti target, setting the arcing current to be 110-120mA, the magnetic filtering current to be 3.0A and the voltage to be 24.2V;

(3) the sputtering time under the bias voltage of each matrix is 30-120 s;

(4) obtaining a Ti ion sputtering layer with the thickness of 150nm-600nm on the surface of the matrix injected with Ti ions;

and finishing the preparation of the coating with the gradient coating on the surface of the blade.

The invention has the beneficial effects that: the invention discloses a clamp for preparing a coating on a selected area of the surface of a blade and a preparation method of the coating, and compared with the prior art, the clamp has the following improvements:

(1) the invention designs a fixture for preparing a coating on a selected area of the surface of a blade, which can clamp and fix the blade when a hard coating is sprayed on the surface of an engine blade or a turbine blade, and the coating meeting the requirements of erosion and fatigue performance is prepared on the surface of the blade by using a zoned coating process, so that the requirement of locally spraying the hard coating on the surface of the engine blade or the turbine blade is met, erosion damage on the surface of the blade is reduced, and the fatigue strength of the blade meets the use requirement;

(2) meanwhile, according to the service requirement of the blade, the distance between the upper end cover and the lower end cover is adjusted by adjusting the connecting bolts between the fixed shaft and the lower cover plate and between the cover plate bracket and the upper cover plate and adjusting the position of the fixed bolt passing through the third sliding fixed groove, so that the dislocation depth between the upper end cover and the lower end cover is adjusted, the size of a clamping gap is adjusted, the control of the size of an ion release gap is realized, and a gradient coating and a non-gradient coating meeting the erosion and fatigue performance requirements are prepared on the surface of the blade;

(3) in addition, the fixture can adjust the relative positions of the blade fixing shaft and the upper cover plate and the lower cover plate by adjusting the positions of the hexagon bolts in the first sliding fixing groove and the second sliding fixing groove according to the sizes of different engine blades or turbine blades, so that the coating meeting the requirements of erosion and fatigue performance can be prepared for the blades with different sizes, and the fixture has the advantages of simplicity and convenience in use and reasonable design.

Drawings

FIG. 1 is a schematic structural view of a coating fixture for selective preparation of blade surfaces according to the present invention.

Fig. 2 is a schematic structural view of the blade fixing shaft of the present invention.

Fig. 3 is a schematic structural view of the cover plate bracket of the present invention.

Fig. 4 is a schematic structural diagram of the upper cover plate of the present invention.

Fig. 5 is a partially enlarged view of the upper cover plate a of the present invention.

Fig. 6 is a schematic structural view of the lower cover plate of the present invention.

Fig. 7 is a partially enlarged view of the lower cover plate B of the present invention.

FIG. 8 is a schematic view of a coating with a graded coating on selected areas prepared on the surface of a blade by ion plating according to example 1 of the present invention.

FIG. 9 is a schematic view of the coating of embodiment 2 of the present invention prepared by ion plating on the surface of the blade without a graded coating in selected areas.

Fig. 10 is a schematic view of the structure of the blade of the present invention.

Wherein: 1. the blade fixing shaft, 11, a flange plate, 12, a connecting shaft, 13, a connecting head, 131, a tenon part clamping groove, 132, a clamping protrusion, 133, a first threaded connecting hole, 134, a second threaded connecting hole, 135, a third threaded connecting hole, 2, a cover plate bracket, 21, a fourth threaded connecting hole, 22, a fifth threaded connecting hole, 3, an upper cover plate, 31, an upper top plate, 311, a first fixing connecting hole, 312, a first sliding fixing groove, 32, an upper left vertical plate, 33, an upper left baffle, 34, an upper right vertical plate, 341, a third sliding fixing groove, 35, an upper end cover, 351, an arc-shaped groove, 352, a first blade limiting groove, 36, an upper front baffle, 4, a lower cover plate, 41, a lower bottom plate, 411, a second fixing connecting hole, 412, a second sliding fixing groove, 42, a lower right vertical plate, 43, a lower right baffle, 44, a lower left vertical plate, 45, an arc-shaped protrusion, 452. a second blade limiting groove 46, a lower front baffle plate 5 and a blade;

in fig. 8, reference numeral 1 denotes a graded coating layer;

in fig. 9, reference numeral 2 indicates no graded coating;

in fig. 10, reference numeral 3 denotes a blade dovetail portion.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following further describes the technical solution of the present invention with reference to the drawings and the embodiments.

Referring to the drawings of fig. 1-10, the fixture for preparing the coating on the selected area of the blade surface and the preparation method of the coating are shown, the fixture for preparing the coating on the selected area of the blade surface comprises a blade fixing shaft 1, a cover plate support 2, an upper cover plate 3 and a lower cover plate 4, the blade fixing shaft 1 is connected with the cover plate support 2, the upper cover plate 3 is installed on the upper end face of the cover plate support 2, the lower cover plate 4 is installed on the lower end face of the blade fixing shaft 1, and the upper cover plate 3 is connected with the lower cover plate 4 in a staggered and clamped mode.

The blade fixing shaft 1 comprises a flange plate 11, a connecting shaft 12 and a connector 13, wherein the flange plate 11 is arranged at the left end of the blade fixing shaft, the connecting shaft 12 is arranged at the right end of the flange plate 11, and the flange plate 11 is connected with the connector 13 through the connecting shaft 12; the connecting head 13 is of a U-shaped structure and comprises a tenon portion clamping groove 131, a clamping protrusion 132, a first threaded connecting hole 133, a second threaded connecting hole 134 and a third threaded connecting hole 135, the tenon portion clamping groove 131 is arranged in the middle of the connecting head 13 and is a groove portion in the middle of the connecting head 13, and when the blade tenon connecting device is used, the blade tenon portion is clamped and connected, the clamping protrusion 132 is arranged at the upper end and the lower end of the outer portion of the tenon portion clamping groove 131, the blade tenon portion clamped into the tenon portion clamping groove 131 is limited, the blade tenon portion is prevented from slipping when blades are sprayed, the second threaded connecting hole 134 is symmetrically arranged on the upper clamping protrusion, the third threaded connecting hole 135 is symmetrically arranged on the lower clamping protrusion, and the first threaded connecting hole 133 is symmetrically arranged on the side wall of the connecting head at the upper portion of the tenon portion clamping groove 131 and;

the apron support 2 be U type groove structure, and be provided with fourth threaded connection hole 21 and fifth threaded connection hole 22 on the upper and lower both ends U-shaped groove lateral wall of apron support 2 respectively, fifth threaded connection hole 22 uses with the cooperation of first threaded connection hole 133, during the use, passes fifth threaded connection hole 22 and first threaded connection hole 133 with the hex bolts in proper order, is connected blade fixed axle 1 with apron support 2.

The upper cover plate 3 comprises an upper top plate 31, an upper left vertical plate 32, an upper left baffle 33, an upper right vertical plate 34, an upper end cover 35 and an upper front baffle 36, the upper top plate 31 is the top plate of the upper cover plate 3, the upper left vertical plate 32 is arranged on the left side of the upper top plate 31, the upper left baffle 33 is arranged on the left side of the front end of the upper top plate 31, the upper right vertical plate 34 is arranged on the right side of the upper top plate 31, the upper end cover 35 is in an inverted triangle shape and is arranged at the rear end of the upper top plate 31, the upper front baffle 36 is arranged at the front end of the upper top plate 31 and is connected with the upper left baffle 33, a first fixed connecting hole 311 is formed in the upper top plate 31, the first fixed connecting hole 311 is matched with the fourth threaded connecting hole 21 for use, and a hexagonal bolt sequentially penetrates through the first fixed connecting hole 311 and the fourth threaded connecting hole 21 to connect;

the lower cover plate 4 comprises a lower bottom plate 41, a lower right vertical plate 42, a lower right baffle 43, a lower left vertical plate 44, a lower end cover 45 and a lower front baffle 46, wherein the lower bottom plate 41 is a bottom plate of the lower cover plate 4, the lower right vertical plate 42 is arranged on the right side of the lower bottom plate 41 and is in matched staggered clamping with the upper right vertical plate 44, the lower right baffle 43 is arranged on the right side part of the front end of the lower bottom plate 41 and is matched with the upper left baffle 33 for use to limit the blade fixing shaft 1, the lower left vertical plate 44 is arranged on the left side of the lower bottom plate 41 and is in matched staggered clamping with the upper left vertical plate 32, the lower end cover 45 is triangular and is arranged at the rear end of the lower bottom plate 41, and the lower front baffle 46 is arranged at the front end of the lower bottom plate 41 and is; a second fixed connecting hole 411 is formed in the lower base plate 41, the second fixed connecting hole 411 is matched with the third threaded connecting hole 135 for use, and when the blade fixing shaft 1 is used, the blade fixing shaft passes through the second fixed connecting hole 411 and the third threaded connecting hole 135 in sequence through a hexagon bolt, so that the blade fixing shaft 1 is connected with the lower cover plate 4;

third sliding fixing grooves 341 are correspondingly arranged on the upper left vertical plate 32, the lower right vertical plate 42, the upper right vertical plate 34 and the lower left vertical plate 44, and are used for fixing the upper left vertical plate 32, the lower right vertical plate 42, the upper right vertical plate 34 and the lower left vertical plate 44 in a staggered manner;

the upper end cover 35 is provided with an arc-shaped groove 351 and a first blade limiting groove 352, the arc-shaped groove 351 is a bevel edge of an inverted triangle, and the first blade limiting groove 352 is arranged at the lower end of the arc-shaped groove 351; the lower end cover 45 is provided with an arc-shaped protrusion 451 and a second blade limiting groove 452, the arc-shaped protrusion 451 is a triangular bevel edge, and the second blade limiting groove 452 is arranged at the upper end of the arc-shaped protrusion 451; the arc-shaped groove 351 and the arc-shaped protrusion 451 are matched for use to form a clamping gap for clamping the front end part of the blade, and the radians of the arc-shaped groove 351 and the arc-shaped protrusion 451 are the same as the radians of the front end part of the blade; spacing recess 352 of first blade and the cooperation of the spacing recess 452 of second blade are used, carry out the joint to the upper and lower both sides portion of joint blade front end, during the use, through with upper end cover 35 and lower end cover 45 dislocation joint, form the joint gap, can satisfy the spraying that has gradual change layer coating and no gradual change layer coating simultaneously through the gap size in adjustment joint gap.