A static test device for applying gas load to aeroengine blades

Abstract

The present application belongs to the field of testing mechanical components of aircraft engine blades, and in particular, relates to a static test device for applying gas loads to aircraft engine blades. Loading bags and loading plates of different specifications and shapes can be designed to be arranged along the length direction of the blades, thereby adapting to blade shapes with complex spatial structures. Loading bags and loading plates of different shapes and sizes can be designed according to different aerodynamic regions of the blades to achieve the application of different aerodynamic forces, so as to conduct test verification under load conditions that are closer to their actual working conditions.

Description

Technical Field

[0001] The present application belongs to the field of testing mechanical components of aircraft engine blades, and in particular, relates to a static test device for applying gas loads to aircraft engine blades. Background Art

[0002] In aviation turbine engines, the working conditions of various blades (fan, compressor, turbine rotor blades, stator blades) have a great impact on engine performance. In order to make the structural design and stress analysis of the blades more reliable, static load testing of the blades under working conditions is an important means to ensure their reliability.

[0003] In normal operation, the blades will be subject to aerodynamic loads (mainly including aerodynamic force and aerodynamic bending moment) generated by the gas in the engine airflow channel and centrifugal loads generated by rotation around the axis (stator blades and guide vanes do not bear centrifugal loads). In the blade component test, the current commonly used method for applying aerodynamic loads on the blades is to equate the aerodynamic loads to concentrated forces based on the stress equivalence principle and apply loads in a square area around the point of force application. Taking the static test device for gas loads on stator blades as an example, Figure 3 The middle blade 43 is fixed to the first column 41 and the second column 45 by the blade root fixing plate 42 and the blade tip fixing plate 44, and simulates the actual installation method of the stator blade; the blade is loaded by the weight 46, and the load acts on the blade through the long plate 48, and the micrometer 47 is used to measure the displacement of the point on the back of the blade corresponding to the loading center.

[0004] Figure 3 In the test scheme shown, when the blade is simplified to a beam structure, a gas load (simplified to a uniformly distributed load for the sake of simplicity of calculation) and a concentrated force (the concentrated load is set to the middle of the beam for the sake of simplicity of calculation) are applied to the beam structure. The comparison diagram of the shear force diagram and the bending moment diagram of the beam structure is shown in the figure below. Figure 7-Figure 12 As shown. Figure 7 , Figure 8 , Fig. 9 It can be found that if the reliability of the support positions at both ends of the blade is evaluated according to the stress equivalence principle, F=qL, where F is the concentrated force, L is the length, and q is the uniformly distributed load; at this time, the shear force and bending moment at the supports at both ends of the blade under the influence of concentrated force or aerodynamic load are the same, that is, the stress is equivalent.

[0005] However, for other sections, the shear force and bending moment caused by concentrated force and gas load are not the same, that is, the reliability analysis of non-test sections when using concentrated force loading is quite different from the reliability analysis of non-test sections when using aerodynamic load loading. For example, the axial deflection of the compressor stator blade is an important parameter. If the deflection is too large, it will collide with the rotor blade in front. Figure 3In the test shown, accurate axial deflection is required to analyze its reliability. When F = qL, Fig.10 , 11 、12 The deflection of the concentrated force at L / 2 is:

[0006]

[0007] Where: E—elastic modulus; I—moment of inertia.

[0008] The deflection of the gas load at L / 2 is:

[0009]

[0010] According to equations (1) and (2), it can be found that the deflection of the concentrated force and the gas load at L / 2 is different, and the actual bending axis equation is also different. Therefore, the test method of using the stress equivalence principle to equate the aerodynamic load to the concentrated force is not conducive to the reliability analysis of the non-assessed section. From the perspective of comprehensive reliability test analysis of the blade, the aerodynamic load should not be equivalent to the concentrated force for loading.

[0011] At the same time according to Figure 3 It can be found that when the loading plate 48 is used to apply concentrated force in the existing test scheme, the concentrated force will apply contact pressure to the blade through the loading plate 48, but since the contact area between the loading plate 48 and the blade is small, the contact position between the blade and the loading plate 48 is subjected to a large pressure, and the pressure at this contact position is far greater than the pressure that should be present under the working state, that is, the pressure at this contact position is over-tested, which can easily lead to damage here, resulting in abnormal damage mode of the blade, which brings inconvenience to the development and verification process of the blade. Summary of the invention

[0012] In order to solve the above problems, the present application provides a static test device for applying gas load to an aircraft engine blade, comprising: a loading unit and a bracket for mounting the loading unit;

[0013] The loading unit includes a loading rod, a loading plate and a loading capsule; the loading rod includes a connecting rod and a movable rod, the connecting rod is connected to a bracket, a dynamometer is installed on the loading rod, the movable rod moves axially relative to the connecting rod, the movable rod is connected to the loading plate, a loading capsule is installed on a side of the loading plate away from the movable rod, the loading capsule has a cavity, and the cavity is filled with fluid; the loading capsule is in contact with the aircraft engine blade test piece;

[0014] The technical effects brought about by the above technical features are: according to the traditional blade loading method recorded in the background art, the loading is uneven, and the present application adopts a flexible loading method, through which the loading bag is in full contact with the surface of the aircraft engine blade, and uses the principle of the same pressure of the fluid to make the gas load on the surface of the aircraft engine blade uniform;

[0015] The bracket comprises a support plate and fixing plates installed at both ends of the support plate, wherein the support plate comprises a plurality of long grids, wherein the connecting rod of the loading unit is connected to the long grids and slides in the long grids; the loading unit comprises a plurality of loading units, which are distributed along the length direction of the bracket, and the plurality of loading units are connected to the same loading capsule;

[0016] The technical effect brought about by the above-mentioned technical features is that the same loading bag can more advantageously apply a uniform load. In addition, because the surface profile of the aircraft engine blades is uneven and different blades have different surface profiles, the bracket adopts the form of multiple grids to adaptively install the loading unit, so that the loading device can be adjusted according to the surface profile of the aircraft engine blades, thereby achieving uniform loading of the aircraft engine blades.

[0017] Preferably, the loading plate has a groove for accommodating the loading capsule on one end surface connected to the loading capsule, and the groove has an arc edge with fewer edges and corners to avoid damaging the loading capsule.

[0018] Preferably, the support plates are distributed in an arc shape along the width direction of the aircraft engine blade test piece;

[0019] The technical effect brought about by the above-mentioned technical features is: according to the profile of the engine blade test piece, the support plate of the support plate surface can be close to the profile of the engine blade test piece to a certain extent. When the loading unit is installed on the support plate through profile proximity, the force direction of the loading unit is perpendicular to the surface of the engine blade test piece, thereby better simulating the real aerodynamic load environment.

[0020] Preferably, when the gas load applied to the aeroengine blade is less than a first preset value, the fluid filled in the loading bag is gas, and when the gas load applied to the aeroengine blade is greater than the first preset value, the fluid filled in the loading bag is liquid;

[0021] The technical effect brought by the above technical features is: when the gas load applied to the aircraft engine blade is less than the first preset value, when the fluid in the loading bag is gas, the deformation of the loading bag caused by the weight of the fluid itself can be reduced; the loading bag is prevented from forming a water droplet shape, thereby preventing the loading bag 5 from being unable to fully fit with the aircraft engine blade when the loading force is small;

[0022] However, when the gas load applied to the aircraft engine blade is greater than the first preset value, because the gas has a large compression ratio, when the loading force is too large, the gas compression amount is large, which is not conducive to loading, so it is more appropriate to use liquid.

[0023] Preferably, when the gas load applied to the aeroengine blade is less than a second preset value, the material of the loading bag is elastic, and when the gas load applied to the aeroengine blade is greater than the second preset value, the material of the loading bag is a flexible non-elastic material;

[0024] The technical effect brought by the above technical features is: when the loaded load becomes larger, the elastic loading bag loses stability due to elasticity, that is, when the load is greater than the second preset value, when the loading continues, the elastic loading bag has its own elastic modulus lower than the expected value, resulting in the increase of the fluid pressure of the loading bag being much smaller than the increase of the force-bearing area of ​​the loading bag, thereby causing the applied load and the load received by the loading blade to be nonlinear, therefore, the material of the loading bag is a flexible material without elasticity;

[0025] The method for determining the second preset value includes: using a loading bladder made of elastic material, and using the loading bladder to load the aeroengine blade according to a plurality of preset first loads, measuring the first load of the aeroengine blade, and drawing a first load-load curve diagram; using a loading bladder made of flexible non-elastic material, and using the loading bladder to load the aeroengine blade according to a plurality of preset second loads, measuring the second load of the aeroengine blade, and drawing a second load-load curve diagram;

[0026] Obtain a first interval in which the derivative of the first load-load curve diagram meets the preset conditions, and use the first load corresponding to the first interval as the first range of the loading bag of the elastic material; obtain a second interval in which the derivative of the second load-load curve diagram meets the preset conditions, and use the second load corresponding to the second interval as the second range of the loading bag of the flexible non-elastic material; the intersection of the first range and the second range is the second preset value.

[0027] Preferably, the initial pressure of the loading bag fluid is equal to the atmospheric pressure, that is, the loading bag has a good deformation ability and can be fitted with the surface of the aircraft engine blade before loading.

[0028] Preferably, the connecting rod of the loading rod is Y-shaped, and comprises a first rod, a second rod and a third rod, the first rod and the second rod are connected to the bracket along the width direction of the aircraft engine blade test piece, the third rod is connected to the movable rod, and the load direction and position of the movable rod on the loading bag are adjusted by adjusting the length and position of the first rod and the second rod;

[0029] Preferably, the loading units include multiple ones distributed along the length direction of the bracket, and each of the loading units has a loading bag. Because the shape and size of the loading bag are different according to the corresponding blade, it can fit better and load more conveniently when the surface of the aircraft engine blade changes greatly.

[0030] Preferably, each loading bag has an inlet mouth with an external thread, and the inlet mouth passes through the external thread to be connected to the internal thread hole of the loading rod through the loading plate, the end of the inlet mouth is conical, and the lower end of the internal thread hole of the loading rod has a conical protrusion, and when the inlet mouth is screwed into the internal thread hole, the conical protrusion blocks the conical end of the inlet mouth to achieve sealing.

[0031] The advantages of the present application include: loading bags and loading plates of different specifications and shapes can be designed to be arranged along the length direction of the blade, thereby adapting to the blade shape with complex spatial structure; and loading bags and loading plates of different shapes and sizes can be designed according to different aerodynamic areas of the blade to achieve the application of different aerodynamic forces, so as to carry out experimental verification under load conditions that are closer to its actual working state. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a loading unit in Example 1;

[0033] Figure 2 is a schematic diagram of the bracket of Example 1;

[0034] Figure 3 Background technology Schematic diagram of traditional loading scheme;

[0035] Figure 4 This is a schematic diagram of a slice of an aircraft engine blade;

[0036] Figure 5 is a schematic diagram of the loading capsule;

[0037] Figure 6 It is a schematic diagram of the internal threaded hole of the loading rod;

[0038] Figure 7 This is the concentrated force diagram of the traditional test device;

[0039] Figure 8 is the force diagram of the actual gas load;

[0040] Fig. 9 This is the concentrated force shear diagram of the traditional test device;

[0041] Fig.10 is the shear force diagram of the actual gas load;

[0042] Fig.11 This is the concentrated force bending moment diagram of the traditional test device;

[0043] Fig.12 Bending moment diagram for actual gas load. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0045] Embodiment 1: The airflow state in the working area of ​​the blade is complex. Since the present invention focuses on the method of applying gas load to the blade, the airflow state on the blade surface is not analyzed. It is only assumed that the pressure difference between the blade basin and the blade back at each position in the blade structure is P.

[0046] like Figure 1 The loading unit 11 shown includes a loading rod 1, a loading disk 4 and a loading capsule 5; a dynamometer 2 is installed on the loading rod 1, the loading rod 1 includes a connecting rod and a movable rod, the connecting rod is connected to a bracket 22, the movable rod moves axially relative to the connecting rod, the movable rod is connected to the loading disk 4, a loading capsule 5 is installed on a side of the loading disk 4 away from the movable rod, the loading capsule 5 has a cavity, and the cavity is filled with fluid; the loading capsule 5 is in contact with the aircraft engine blade test piece; the loading capsule 5 can be designed as a rectangular parallelepiped structure and form an air cavity, the loading capsule 5 has an inlet nozzle, the inlet nozzle 3 is a cylindrical structure with a hole in the middle, and the liquid can be filled into the air cavity through the middle hole of the inlet nozzle 3. After being filled with liquid, the inlet nozzle 3 can be connected to the loading rod 1 through a thread, because the connection method between the loading rod 1 and the inlet nozzle 3 is designed as a conical surface sealing structure Figure 5 , Figure 6 As shown, the connection between the two has a good sealing effect on the liquid in the air cavity.

[0047] Since the loading capsule 5 is a thin rubber shell filled with liquid, it has good deformation ability. Since there are no sharp edges on the loading plate and the blades, and the pressure difference P between the blade basin and the blade back is not very large, the loading capsule 5 is not easy to be damaged. The force F of the loading rod on the loading capsule 5 can be obtained by connecting the loading rod to the dynamometer. Assuming that the surface area of ​​the loading capsule 5 and the blade is S, the pressure P of the loading rod on the surface of the blade basin through the loading capsule 5 is:

[0048]

[0049] According to the knowledge of fluid mechanics, the pressure at all places on the fluid surface is the same. At this time, the pressure distribution of the pressure P on the surface of the blade basin is also very uniform, meeting the test requirements;

[0050] Figure 2 The middle bracket includes a fixed plate and a support plate. The fixed plate is fixed at a fixed end. The support plate is installed between the fixed plates. It is a plurality of rectangular plates with rectangular holes in the middle distributed along the arc. The bracket is fixed through these rectangular holes. Figure 5 The loading bag 5 and loading unit connected to the dynamometer shown in the figure, and because the support plate is distributed in an arc shape, can adapt to blades with complex spatial structures, so that the loading rod is basically perpendicular to the surface of the blade basin and remains basically vertical, so that there is no relative sliding between the loading bag 5 and the blade during the loading process.

[0051] In summary, the present application can adapt to the blade shape with complex spatial structure by designing loading bags 5 and loading plates of different specifications and shapes so that they are arranged along the length direction of the blade. Loading bags 5 and loading plates of different shapes and sizes can be designed according to the different aerodynamic regions of the blade to achieve the application of different aerodynamic forces, so as to conduct experimental verification under load conditions that are closer to its actual working state.

[0052] Embodiment 2: The present application provides a static test device for applying a gas load to an aircraft engine blade, comprising: a loading unit 11 and a bracket 22 for mounting the loading unit 11;

[0053] The loading unit 11 includes a loading rod 1, a loading plate 4 and a loading capsule 5; the loading rod 1 includes a connecting rod and a movable rod, the connecting rod is connected to the bracket 22, the movable rod moves axially relative to the connecting rod, the movable rod is connected to the loading plate 4, the loading capsule 5 is installed on a side of the loading plate 4 away from the movable rod, the loading capsule 5 has a cavity, and the cavity is filled with fluid; the loading capsule 5 is in contact with the aircraft engine blade test piece;

[0054] The technical effects brought by the above technical features are: according to the traditional blade loading method recorded in the background art, the loading is uneven, and the present application adopts a flexible loading method, through which the loading bag 5 is in full contact with the surface of the aircraft engine blade, and the principle of the same pressure of the fluid is used to make the gas load on the surface of the aircraft engine blade uniform;

[0055] The support 22 has a support plate 8 and fixed plates 7 installed at both ends of the support plate 8, the support plate 8 has a plurality of long grids, the connecting rod of the loading unit 11 is connected to the long grids and slides in the long grids; the loading unit 11 includes a plurality of loading units 11 distributed along the length direction of the support 22, and the plurality of loading units 11 are connected to the same loading capsule 5;

[0056] The technical effect brought about by the above-mentioned technical features is that the same loading bag 5 can more advantageously apply a uniform load. In addition, because the profile of the aircraft engine blades is uneven and different blades have different profiles, the bracket 22 adopts the form of multiple grids to adaptively install the loading unit 11, so that the loading device can be adjusted according to the profile of the aircraft engine blades to achieve uniform loading of the aircraft engine blades.

[0057] Furthermore, the loading plate 4 has a groove for accommodating the loading capsule 5 on one end surface connected to the loading capsule 5 , and the groove has a circular arc edge with fewer edges and corners to avoid damaging the loading capsule 5 .

[0058] Furthermore, the support plate 8 is distributed in an arc shape along the width direction of the aircraft engine blade test piece;

[0059] The technical effect brought about by the above-mentioned technical features is: according to the profile of the engine blade test piece, the arc surface of the support plate 8 can be close to the profile of the engine blade test piece to a certain extent. When the loading unit 11 is installed on the support plate 8 through profile proximity, the force of the loading unit 11 is transmitted perpendicular to the engine blade test piece, thereby better simulating the real aerodynamic load environment.

[0060] Further, when the gas load applied to the aeroengine blade is less than the first preset value, the fluid filled in the loading bag 5 is gas, and when the gas load applied to the aeroengine blade is greater than the first preset value, the fluid filled in the loading bag 5 is liquid;

[0061] The technical effect brought by the above technical features is: when the gas load applied to the aircraft engine blade is less than the first preset value, when the fluid in the loading bag 5 is gas, the deformation of the loading bag 5 caused by the weight of the fluid itself can be reduced; the loading bag 5 is prevented from forming a water droplet shape, thereby preventing the loading bag 5 from being unable to fully fit with the aircraft engine blade when the loading force is small;

[0062] However, when the gas load applied to the aircraft engine blade is greater than the first preset value, because the gas has a large compression ratio, when the loading force is too large, the gas compression amount is large, which is not conducive to loading, so it is more appropriate to use liquid.

[0063] Further, when the gas load applied to the aeroengine blade is less than the second preset value, the material of the loading bag 5 is elastic, and when the gas load applied to the aeroengine blade is greater than the second preset value, the material of the loading bag 5 is not elastic;

[0064] The method for determining the second preset value comprises: using a loading capsule (5) made of elastic material, and using the loading capsule (5) to load an aircraft engine blade according to a plurality of preset first loads, measuring a first load on the aircraft engine blade, and drawing a first load-load curve diagram; using a loading capsule (5) made of flexible non-elastic material, and using the loading capsule (5) to load an aircraft engine blade according to a plurality of preset second loads, measuring a second load on the aircraft engine blade, and drawing a second load-load curve diagram;

[0065] A first interval in which the derivative of the first load-load curve diagram meets the preset conditions is obtained, and a first load corresponding to the first interval is used as a first range of the loading bag (5) of the elastic material; a second interval in which the derivative of the second load-load curve diagram meets the preset conditions is obtained, and a second load corresponding to the second interval is used as a second range of the loading bag (5) of the flexible non-elastic material; the intersection of the first range and the second range is the second preset value.

[0066] The technical effect brought about by the above technical features is that when the loaded load becomes larger, the elastic loading bag 5 loses stability due to its elasticity, so a non-elastic material is used for the case where the loaded load is larger.

[0067] Furthermore, the initial pressure of the fluid in the loading bag 5 is equal to the atmospheric pressure, that is, the loading bag 5 has a good deformation ability and can be fitted with the surface of the aircraft engine blade before loading.

[0068] Furthermore, the connecting rod of the loading rod 1 is Y-shaped, having a first rod, a second rod and a third rod. The first rod and the second rod are connected to the bracket 22 along the width direction of the aircraft engine blade test piece, and the third rod is connected to the movable rod. By adjusting the length and position of the first rod and the second rod, the load direction and position of the movable rod on the loading bag 5 are adjusted, which is not illustrated in the accompanying drawings.

[0069] Furthermore, the loading units 11 include a plurality of loading units 11 distributed along the length direction of the bracket 22 , and each of the loading units 11 has a loading capsule 5 .

[0070] Furthermore, each loading bag 5 has an inlet mouth 3, and the inlet mouth 3 has an external thread. The inlet mouth 3 passes through the loading plate 4 through the external thread and is connected to the internal thread hole of the loading rod 1. The end of the inlet mouth 3 is conical, and the lower end of the internal thread hole of the loading rod 1 has a conical protrusion. When the inlet mouth 3 is screwed into the internal thread hole, the conical protrusion blocks the conical end of the inlet mouth 3 to achieve sealing.

[0071] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A static test device for applying gas load to an aircraft engine blade, characterized in that: include: A loading unit (11) and a bracket (22) for mounting the loading unit (11); The loading unit (11) comprises a loading rod (1), a loading disc (4) and a loading capsule (5); a dynamometer (2) is mounted on the loading rod (1); the loading rod (1) comprises a connecting rod and a movable rod; the connecting rod is connected to a bracket (22); the movable rod moves axially relative to the connecting rod; the movable rod is connected to the loading disc (4); a loading capsule (5) is mounted on a side of the loading disc (4) away from the movable rod; the loading capsule (5) has a cavity filled with fluid; the loading capsule (5) contacts an aircraft engine blade test piece; The bracket (22) comprises a support plate (8) and fixing plates (7) mounted at both ends of the support plate (8), wherein the support plate (8) comprises a plurality of long grids, and the connecting rod of the loading unit (11) is connected to the long grids and slides in the long grids; When the gas load applied to the aeroengine blade is less than a second preset value, the material of the loading bag (5) is an elastic material; when the gas load applied to the aeroengine blade is greater than the second preset value, the material of the loading bag (5) is a flexible non-elastic material; The method for determining the second preset value comprises: using a loading capsule (5) made of elastic material, and using the loading capsule (5) to load an aircraft engine blade according to a plurality of preset first loads, measuring a first load on the aircraft engine blade, and drawing a first load-load curve diagram; using a loading capsule (5) made of flexible non-elastic material, and using the loading capsule (5) to load an aircraft engine blade according to a plurality of preset second loads, measuring a second load on the aircraft engine blade, and drawing a second load-load curve diagram; A first interval in which the derivative of the first load-load curve diagram meets the preset conditions is obtained, and a first load corresponding to the first interval is used as a first range of the loading bag (5) of the elastic material; a second interval in which the derivative of the second load-load curve diagram meets the preset conditions is obtained, and a second load corresponding to the second interval is used as a second range of the loading bag (5) of the flexible non-elastic material; the intersection of the first range and the second range is the second preset value.

2. The static test device for applying gas load to an aircraft engine blade according to claim 1, characterized in that: The loading units (11) include a plurality of loading units (11), the plurality of loading units (11) are distributed along the length direction of the bracket (22), and the plurality of loading units (11) are connected to the same loading capsule (5).

3. The static test device for applying gas load to aeroengine blades according to claim 1, characterized in that: The support plate (8) is distributed in an arc shape along the width direction of the aircraft engine blade test piece.

4. The static test device for applying gas load to aeroengine blades according to claim 1, characterized in that: When the gas load applied to the aircraft engine blade is less than a first preset value, the fluid filled in the loading bag (5) is gas; when the gas load applied to the aircraft engine blade is greater than the first preset value, the fluid filled in the loading bag (5) is liquid.

5. The static test device for applying gas load to aeroengine blades according to claim 3, characterized in that: The initial pressure of the fluid in the loading bladder (5) is equal to the atmospheric pressure.

6. The static test device for applying gas load to aeroengine blades according to claim 1, characterized in that: The connecting rod of the loading rod (1) is Y-shaped and comprises a first rod, a second rod and a third rod. The first rod and the second rod are connected to a bracket (22) along the width direction of the aircraft engine blade test piece. The third rod is connected to the movable rod. By adjusting the length and position of the first rod and the second rod, the load direction and position of the movable rod on the loading bag (5) are adjusted.

7. The static test device for applying gas load to an aircraft engine blade according to claim 1, characterized in that: The loading units (11) include a plurality of loading units (11) distributed along the length direction of the bracket (22), and each loading unit (11) has a loading bag (5).

8. The static test device for applying gas load to aeroengine blades according to claim 7, characterized in that: Each loading bag (5) has an inlet mouth (3) having an external thread. The inlet mouth (3) passes through the loading plate (4) through the external thread and is connected to the internal thread hole of the loading rod (1). The end of the inlet mouth (3) is conical, and the lower end of the internal thread hole of the loading rod (1) has a conical protrusion. When the inlet mouth (3) is screwed into the internal thread hole, the conical protrusion blocks the conical end of the inlet mouth (3) to achieve sealing.

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