A force measurement device and method for shrouded turbine blades

Abstract

The present invention relates to a force measuring device for shrouded turbine blades, which belongs to the technical field of electronic measuring instrument manufacturing, and solves the problem in the prior art that the force measurement of the contact surface of shrouded turbine blades is difficult to locate and has low accuracy. The present invention includes a mounting base and at least one force measuring assembly that is adjustably arranged on the mounting base; the force measuring assembly includes a first force transmission structure base, a second force transmission structure base, a third force transmission structure base, three force transmission structures, a friction block base and a friction block; the mounting base has a mounting plane, which is a vertical plane; the three force transmission structures are arranged in the direction of the coordinate axis of the first coordinate system, and the length, width and height directions of the mounting base constitute a second coordinate system, and there is a conversion relationship between the first coordinate system and the second coordinate system. The present invention avoids the influence of the contact force level on the contact force measurement error through the specific arrangement of the friction block and the force transmission structure, and improves the positioning accuracy of the force measuring assembly and the accuracy of the force measurement result.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic measuring instrument manufacturing, and in particular relates to a force measuring device and method for shrouded turbine blades. Background Art

[0002] Structures such as turbine blades with shrouds or fan blades with convex shoulders that use friction vibration reduction require contact force measurement to obtain contact surface parameters and reveal mechanical properties. Current measurement schemes usually use commercial multi-dimensional force measuring elements or mechanically decoupled force measuring structures. Commercial force measuring elements often focus on the versatility of the elements, so they are not applicable to special application scenarios.

[0003] For the blade crown structure of the turbine blade of an aircraft engine, the structural dimensions of its contact surface are often small (about 5 to 10 mm), and the blade crown structure includes a variety of structures such as serrated crowns, special-shaped crowns and parallel crowns. The existing multi-dimensional commercial force measuring elements are not operable in terms of structural dimensions or installation and use. The existing mechanical decoupling force measuring structure device is not suitable for the blade crown contact surface of the aircraft engine shrouded turbine blade. The existing device has a complex structure and low measurement accuracy. It cannot be applied to the shapes and angles of the blade crown contact surface of different models of shrouded turbine blades, which leads to the friction plate being difficult to accurately position when measuring the force on the blade crown contact surface of the shrouded turbine blade, and the measurement accuracy cannot be guaranteed. For all the above reasons, the contact force measurement of the contact interface of the shrouded turbine blade of an aircraft engine has always been a difficulty in the field of dry friction research. Summary of the invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a force measurement device for a shrouded turbine blade, so as to solve the problem in the prior art that force measurement of the contact surface of the shrouded turbine blade is difficult to locate and has low accuracy.

[0005] The present invention adopts the following technical solution:

[0006] A force measuring device for a shrouded turbine blade comprises a mounting base and at least one force measuring assembly; the force measuring assembly is adjustably arranged on the mounting base;

[0007] Wherein, the mounting base includes a mounting plane extending in a vertical direction;

[0008] The force measuring assembly comprises a first force transmission structure base, a second force transmission structure base, a third force transmission structure base, three force transmission structures, a friction block base and a friction block; wherein the first force transmission structure base, the second force transmission structure base and the third force transmission structure base are respectively arranged on the installation plane in an adjustable manner, one end of the three force transmission structures are respectively fixedly connected to the first force transmission structure base, the second force transmission structure base or the third force transmission structure base, and the three force transmission structures are orthogonal to each other; the other ends of the three force transmission structures are fixedly connected to the friction block base; the friction block base comprises a platform portion, the friction block is fixedly arranged on the platform portion, and the platform portion is parallel to the installation plane and spaced a distance from each other;

[0009] The three force transmission structures are arranged according to a first rectangular coordinate system (x1-y1-z1), and the three force transmission structures extend along the directions of x1, y1, and z1, respectively; the following linear transformation relationship exists between the first rectangular coordinate system (x1-y1-z1) and a second rectangular coordinate system (x2-y2-z2) with the installation plane as the y2-z2 plane and the normal direction of the installation plane as the x2 direction:

[0010]

[0011]

[0012] Furthermore, a first flat keyway and two slide rail mounting grooves are provided on the mounting plane; the first flat keyway and the two slide rail mounting grooves are arranged parallel to each other and spaced apart; a slide rail is fixedly arranged in the slide rail mounting groove; a positioning platform is provided at the bottom of the first force transmission structure base, the positioning platform is arranged in the first flat keyway and can reciprocate relative to the first flat keyway; sliders are provided at the bottom of the second force transmission structure base and the third force transmission structure base, and the sliders are arranged on the slide rails one by one.

[0013] Furthermore, two groups of second flat key grooves are provided on the installation plane, and the two groups of second flat key grooves are arranged in one-to-one correspondence with the two slide rail installation grooves; the first flat key groove and the two groups of second flat key grooves are both equipped with first threaded holes; the bottoms of the second force transmission structure base and the third force transmission structure base are both provided with third flat key grooves, and the force measuring device also includes a flat key, which is inserted into the second flat key groove and the third flat key groove; the first force transmission structure base, the second force transmission structure base and the third force transmission structure base are respectively fixed to the installation plane by fasteners through corresponding first threaded holes.

[0014] Furthermore, the force transmission structure includes a force sensor adapter block, a force sensor, a force transmission shaft and a connecting shaft connected in sequence; the force sensor adapter block is fixedly connected to the first force transmission structure base, the second force transmission structure base or the third force transmission structure base; the connecting shaft is fixedly connected to the friction block base.

[0015] Furthermore, the lateral bending stiffness K of the force transmission shaft b Less than or equal to axial tension and compression stiffness K p 1%.

[0016] Furthermore, the friction block base also includes three support rod portions, which extend outward from the edge of the friction block base. The three support rod portions are orthogonal to each other and are evenly distributed circumferentially relative to the center of the friction block base.

[0017] Furthermore, the three force transmission structures are respectively fixedly connected to one of the three support rod parts.

[0018] Furthermore, the friction block includes a friction block mounting end and a friction block friction end, the friction block mounting end is fixedly arranged in the middle of the friction block base, and the friction block friction end has a friction block contact surface, and the friction block contact surface is located on the side of the friction block friction end.

[0019] Furthermore, the friction block coincides with the central axis of the friction block base, the intersection of the central axes of the three support rods is located on the friction block contact surface, and there is an angle α between the friction block contact surface and the horizontal plane. The plane where the friction block contact surface is located is the x3-y3 plane, and the direction perpendicular to the friction block contact surface is the z3 direction to construct a third coordinate system x3-y3-z3, which has the following linear transformation relationship with the second coordinate system:

[0020]

[0021] On the other hand, the present invention also relates to a method for measuring force for a shrouded turbine blade, using the force measuring device for a shrouded turbine blade as described above.

[0022] The present invention has at least one of the following beneficial effects:

[0023] (1) The present invention extends a friction block base through a three-way orthogonal force transmission structure, and installs the friction block as a friction pair static part on the friction block base to ensure accessibility. The friction block can be used for contact force measurement of small-sized contact surfaces such as the blade crown contact surface of a turbine blade with a crown on an aircraft engine. Specifically, the friction block is a friction pair static part that matches the blade crown contact surface. It can be designed according to the size and structure of the blade crown contact surface and installed on the friction block base. Since the friction block is located at the end of the three-way orthogonal force transmission structure, the structural size of the friction block is only determined by the friction block itself, and there is no interference between the friction block and the blade crown structure.

[0024] (2) The present invention enables the force measuring component to be adjustably positioned on the mounting plane of the mounting base, so that the position of the force measuring component can be adjusted according to the pressure between the friction block and the contact surface of the blade crown during force measurement, so that the friction block is accurately positioned, the measurement process is not affected by installation errors, and the measurement accuracy is improved.

[0025] (3) The present invention adopts the first coordinate system to arrange the force transmission structure and adopts the third coordinate system to measure the contact force, thereby avoiding the influence of the contact force level on the contact force measurement error, so that the force measurement error is only related to the decoupling degree of the force transmission axis. The angle between the third coordinate system and the second coordinate system can meet the measurement requirements of the contact surface of the crowned turbine blade with different angles.

[0026] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0028] Figure 1 It is a structural schematic diagram of a force measuring device for a shrouded turbine blade according to the present invention;

[0029] Figure 2 A front view of a force measuring device for a shrouded turbine blade according to the present invention;

[0030] Figure 3 It is a schematic diagram of the structure of the installation base;

[0031] Figure 4 It is the front view of the force measuring assembly;

[0032] Figure 5 It is a side view of the force measuring assembly;

[0033] Figure 6 is a structural schematic diagram of a first force transmission structure base;

[0034] Figure 7 is a structural diagram of the second force transmission structure base;

[0035] Figure 8 is a rear view of the second force transmission structure base;

[0036] Fig. 9 For along Figure 8 The cross-sectional view along the middle line BB is a cross-sectional view of the base of the second force transmission structure;

[0037] Fig.10 For along Figure 5 The cross-sectional view along the AA line is a cross-sectional view of the force transmission structure;

[0038] Fig.11 It is the structural diagram of the force sensor adapter block;

[0039] Fig.12 It is the structural diagram of the connecting shaft;

[0040] Fig.13 It is the structural diagram of the friction block base;

[0041] Fig.14 is a schematic diagram of a first coordinate system based on a front view of a friction block base;

[0042] Fig.15 is a schematic diagram of a first coordinate system based on a top view of a friction block base;

[0043] Fig.16 is a schematic diagram of a second coordinate system based on a front view of a friction block base;

[0044] Fig.17 is a schematic diagram of a second coordinate system based on a top view of a friction block base;

[0045] Fig.18 is the structural diagram of the friction block;

[0046] Fig.19 is a top view of the friction block;

[0047] Fig. 20 For along Fig.19 The cross-sectional view of the EE line is the cross-sectional view of the friction block;

[0048] Fig.21 A three-dimensional structural diagram of an application scenario of a force measuring device for a shrouded turbine blade of the present invention for measuring the contact force of the friction surface of the shrouded blade;

[0049] Fig. 22It is a side view of an application scenario of a force measuring device for a shrouded turbine blade of the present invention for measuring the contact force of the friction surface of the shrouded blade;

[0050] Fig.23 For along Fig. 22 The cross-sectional view along the FF line is a cross-sectional view of the friction contact surface position in the application scenario of the present invention.

[0051] In the figure: 1-mounting base; 11-mounting plane; 111-first flat keyway; 112-second flat keyway; 113-first threaded hole; 114-second threaded hole; 115-slide rail mounting groove; 121-bolt hole; 122-mounting groove; 2-first force transmission structure base; 21-positioning platform; 22-first mounting inclined surface; 23-third threaded hole; 24-first countersunk hole; 3-second force transmission structure base; 31-third flat keyway; 32-second countersunk hole; 33-slider mounting surface; 34-second mounting inclined surface; 4-third force transmission structure base; 5-force transmission structure; 51-force sensor adapter block; 511-force sensor mounting surface; 512-base mounting surface; 513-first through hole; 514-third countersunk hole; 52-force Sensor; 53-force transmission shaft; 531-first part; 532-second part; 5321-rib; 533-third part; 54-connecting shaft; 541-friction block base connecting end; 5411-semicircular part; 5412-convex block part; 5413-second through hole; 542-force transmission shaft connecting end; 543-limiting ring; 6-friction block base; 61-platform part; 611-friction block mounting groove; 612-fourth threaded hole; 613-center through hole; 62-support rod part; 621-fifth threaded hole; 7-friction block; 71-friction block friction end; 711-friction block contact surface; 72-friction block clamping platform; 73-friction block mounting end; 8-slide rail; 9-slider; 10-flat key; A-aircraft engine turbine blade. DETAILED DESCRIPTION

[0052] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0053] Example 1

[0054] A specific embodiment of the present invention, as Figure 1 , Figure 2 As shown, a force measuring device for a shrouded turbine blade comprises a mounting base 1 and at least one force measuring assembly, wherein the force measuring assembly is fixedly arranged on the mounting base 1 and its position on the mounting base 1 is adjustable.

[0055] The structure of the mounting base 1 can be a simple rectangle or a Figure 1 , Figure 2 and Figure 3 The irregular shape shown can also be other shapes that are suitable for the structure of the required installation location. Figure 1-Figure 3 The mounting base 1 has a first step portion 12, a second step portion 13 and a third step portion 14 connected in sequence from top to bottom. Figure 1 , Figure 3 A plurality of bolt holes 121 are evenly arranged at the peripheral edge of the third step portion 14 for fixing the mounting base 1 to the target position. Preferably, a mounting groove 122 is also provided at the bottom of the mounting base 1 for engaging with the target position.

[0056] The side surfaces of the first step portion 12, the second step portion 13 and the third step portion 14 in a vertical direction are flush with each other, forming a mounting plane 11. The mounting plane 11 of the mounting base 1 is used for mounting a force measuring assembly.

[0057] like Figure 1-Figure 3 As shown, the mounting plane 11 of the mounting base 1 is provided with a first flat keyway 111, two groups of second flat keyways 112 and two slide rail mounting grooves 115. The first flat keyway 111 is arranged on the second step portion 13, and extends horizontally to the left from the right end surface of the second step portion 13. Each group of second flat keyways 112 includes two parallel and spaced grooves. The first group of second flat keyways 112 is arranged on the first step portion 12, and extends obliquely from the top surface of the first step portion 12 to the lower right. The second group of second flat keyways 112 is arranged on the third step portion 14, and extends from the bottom surface of the third step portion 14 to the upper right. The two groups of second flat keyways 112 are symmetrical about the central axis of the first flat keyway 111. The second flat keyway 112 has the same size as the flat key 10.

[0058] A plurality of groups of first threaded holes 113 are matchedly arranged at the locations where the first flat key groove 111 and the second flat key groove 112 are located.

[0059] The first of the two slide rail mounting grooves 115 is arranged at the edge where the first step portion 12 and the second step portion 13 meet. The slide rail mounting groove 115 extends horizontally to the right from the left end surface of the first step portion 12 and the second step portion 13. The second of the two slide rail mounting grooves 115 is arranged on the third step portion 14 and extends horizontally to the right from the left end surface of the third step portion 14. The width of the two slide rail mounting grooves 115 is greater than the width of the slider 9. A plurality of second threaded holes 114 are formed at the bottom of the slide rail mounting groove 115. The slide rail 8 is fixedly mounted in the slide rail mounting groove 115 by screws and the second threaded holes 114.

[0060] See also Figure 4-Figure 5The force measuring assembly includes a first force transmission structure base 2, a second force transmission structure base 3, a third force transmission structure base 4, three force transmission structures 5, a friction block base 6 and a friction block 7. Among them, one end of the three force transmission structures 5 is fixedly connected to the first force transmission structure base 2, the second force transmission structure base 3 or the third force transmission structure base 4, respectively, and the other end of the three force transmission structures 5 is fixedly connected to the friction block base 6. The friction block 7 is fixedly arranged on the platform portion of the friction block base 6, and the platform portion of the friction block base 6 is parallel to the mounting plane 11 of the mounting base 1 and is spaced apart from each other by a distance.

[0061] The structure of the first force transmission structure base 2 is as follows Figure 6 As shown. A positioning platform 21 is provided at the bottom end of the first force transmission structure base 2, and its size is the same as the first flat keyway 111. A plurality of first countersunk holes 24 are provided on the main body of the first force transmission structure base 2, and their positions and sizes match the first threaded holes 113 at the first flat keyway 111. A first mounting inclined surface 22 and a third threaded hole 23 are provided at the upper end of the first force transmission structure base 2 for mounting the force transmission structure 5.

[0062] like Figure 7 , Figure 8 , Fig. 9 As shown, the second force transmission structure base 3 is similar in structure to the first force transmission structure base 2, and a second installation inclined surface 34 is provided at the upper end. The difference is that a third flat key groove 31 is provided at the bottom of the second force transmission structure base 3, and its size is the same as the flat key 10. When the second force transmission structure base 3 is installed, the third flat key groove 31 is positioned by the flat key 10 and the second flat key groove 112. The second force transmission structure base 3 is provided with a slider mounting surface 33 and a second countersunk hole 32. The width of the slider mounting surface 33 is greater than the width of the slider 9 and equal to the width of the slide rail mounting groove 115. When the second force transmission structure base 3 is installed, the slider mounting surface 33 is fastened to the slider 9 through the second countersunk hole 32. The third force transmission structure base 4 is symmetrical in structure with the second force transmission structure base 3, and has the same characteristics and functions, which will not be repeated.

[0063] See also Figure 1-Figure 2 During installation, the first force transmission structure base 2 is installed at the first flat keyway 111, the second force transmission structure base 3 is installed at the first group of second flat keyways 112, and the third force transmission structure base 4 is installed at the second group of second flat keyways 112, and fastened by screws and first threaded holes 113. The second force transmission structure base 3 and the third force transmission structure base 4 are connected to the slider 9 by screws, and the slider 9 is installed on the slide rail 8.

[0064] See also Figure 5 , Fig.10One end of the force transmission structure 5 is fixedly connected to the support rod portion 62 of the friction block base 6 through a threaded fastener, and the other end is fixedly connected to the mounting inclined surfaces of the first force transmission structure base 2, the second force transmission structure base 3 and the third force transmission structure base 4 through the third threaded hole 23.

[0065] See also Fig.10 Each force transmission structure 5 includes a force sensor adapter block 51 , a force sensor 52 , a force transmission shaft 53 and a connecting shaft 54 ​​.

[0066] See also Fig.11 The force sensor adapter block 51 includes a force sensor mounting surface 511 , a base mounting surface 512 , a first through hole 513 and a third countersunk hole 514 .

[0067] See also Fig.11 The force sensor mounting surface 511 of the force sensor adapter block 51 cooperates with the force sensor 52, and the base mounting surface 512 cooperates with the mounting inclined surfaces of the three force transmission structure bases. Four first through holes 513 are opened around the force sensor adapter block 51, and the positions match the threaded holes on the three force transmission structure bases. A third countersunk hole 514 is opened in the center of the force sensor adapter block 51, and the size matches the screw size required by the force sensor 52. During installation, the screw passes through the third countersunk hole to fix the force sensor 52 and the force sensor adapter block 51 together, and the screw passes through the first through hole 513 to fix the force sensor adapter block 51 on the first force transmission structure base 2, the second force transmission structure base 3 and the third force transmission structure base 4.

[0068] See also Fig.10 The base mounting surface 512 of the force sensor adapter block 51 is fixedly connected to the mounting inclined surfaces of the three force transmission structure bases, the force sensor mounting surface 511 is fixedly connected to one end of the force sensor 52, the other end of the force sensor 52 is fixedly connected to one end of the force transmission shaft 53, the other end of the force transmission shaft 53 is fixedly connected to one end of the connecting shaft 54, and the other end of the connecting shaft 54 ​​is fixedly connected to the friction block base 6.

[0069] like Fig.12As shown, the connecting shaft 54 ​​includes a friction block base connecting end 541, a force transmission shaft connecting end 542 and a stop ring 543. The friction block base connecting end 541 has a semicircular portion 5411 protruding axially outward, a convex portion 5412 protruding radially outward from the center of the semicircular portion 5411, and a second through hole 5413 penetrating the semicircular portion 5411 and the convex portion 5412. The second through hole 5413 is used to connect with the friction block base 6, and its size and position match the fifth threaded hole 621. Preferably, the milling of the end of the support rod portion 62 of the friction block base 6 forms a surface groove suitable for positioning and installing with the convex portion 5412. The force transmission shaft connecting end 542 is provided with an external thread. The stop ring 543 is located between the friction block base connecting end 541 and the force transmission shaft connecting end 542, and its outer diameter is larger than that of the friction block base connecting end 541 and the force transmission shaft connecting end 542.

[0070] See also Fig.10 The force transmission shaft 53 is a hollow shaft structure, and the force transmission shaft 53 is axially divided into a first part 531, a second part 532, and a third part 533. The first end of the first part 531 is fixedly connected to the connecting shaft 54 ​​by a thread, the first end of the second part 532 is fixedly connected to the second end of the first part 531, and the second end of the second part 532 is fixedly connected to the first end of the third part 533. The second end of the third part 533 of the force transmission shaft 53 is fixedly connected to the force sensor 52.

[0071] Furthermore, a threaded hole is formed in the center of the first part 531, and its size is the same as the external thread size of the force transmission shaft connection end 542, and the major thread diameter is smaller than the inner diameter of the second part. The first part 531, the second part 532 and the first end of the third part 533 have the same external diameter. The second end of the third part 533 has a smaller external diameter than the first end and has an external thread, and the external thread size matches the force sensor 52.

[0072] Furthermore, the second portion 532 of the force transmission shaft 53 is a plurality of ribs 5321 uniformly distributed in the circumferential direction. The ribs 5321 of the force transmission shaft 53 are uniformly arranged along the circumferential direction, thereby ensuring that the rigidity of the force transmission shaft 53 in all directions is uniform.

[0073] See also Fig.13 and Fig.14 The friction block base 6 includes a platform portion 61 and three support rod portions 62. The platform portion 61 is parallel to the mounting plane 11 of the mounting base 1 and is spaced apart from the mounting plane 11 by a distance. The platform portion 61 is preferably an equilateral triangle or a hexagon. A square friction block mounting groove 611 is provided at the center of the platform portion 61, and a central through hole 613 is provided at the bottom center of the friction block mounting groove 611.

[0074] See also Fig.13 , Fig.14The three support rods 62 are inclined and protrude from the three vertices of the triangular platform 61 toward the installation plane 11, or are inclined and protrude from the three sides of the hexagonal platform 61 toward the installation plane 11. The central axes of the three support rods 62 are orthogonal to each other, and the central intersection is located on the central vertical line of the platform 61, such as Fig.14 , Fig.15 The central axes of the three support rods 62 extend along the three directions of the first coordinate system x1-y1-z1, respectively. Fig.14 , Fig.15 shown.

[0075] One end of the three support rods 62 is fixedly connected to the platform portion 61, and the other end is milled to remove part of the structure, and a groove is provided on the milled surface, and a fifth threaded hole 621 is provided at the bottom of the groove, and the fifth threaded hole 621 is perpendicular to the milled surface of the support rods 62. In some embodiments, the three support rods 62 are integrally formed with the platform portion 61.

[0076] See also Fig.18 and Fig. 20 The friction block 7 includes a friction block friction end 71, a friction block pressing platform 72 and a friction block mounting end 73 connected in sequence. The friction block friction end 71 is a rectangular block, including a friction block contact surface 711, and the friction block contact surface 711 is the side of the friction block friction end 71 adjacent to the center of the friction block pressing platform 72. The friction block pressing platform 72 is a disc-shaped flat plate with a plurality of through holes evenly distributed around the periphery. The friction block mounting end 73 is a square block with a threaded hole at the bottom.

[0077] The friction block mounting end 73 is inserted into the friction block mounting groove 611, and the fixing screw extends from the central through hole 613 into the threaded hole of the friction block mounting end 73 of the friction block 7, fixing the friction block 7 on the friction block base 6. In order to further improve the installation and fastening degree of the friction block 7, a plurality of fourth threaded holes 612 are further provided on the platform portion 61, the positions of which match the through holes on the friction block pressing platform 72, and the friction block 7 can be further fastened to the friction block base 6 by screws.

[0078] The present invention uses screws to fasten the friction block 7 to the friction block base 6. The friction block 7 serves as a static part of the friction pair. The friction block contact surface 711 of the friction end 71 of the friction block bears the contact force of the relative movement between the friction pairs and transmits the contact force to the friction block base 6.

[0079] In a force measuring device for a shrouded turbine blade of the present invention, the size of the ribs 5321 of the force transmission shaft 53 determines the lateral bending stiffness K of the force transmission shaft 53. b and axial tension and compression stiffness K p and decoupling degree, the size of the rib 5321 can be determined according to the transverse bending stiffness K required by the design.b and axial tension and compression stiffness K p and decoupling degree.

[0080] The decoupling degree can be calculated according to the theoretical formula. Based on the formula, the required lateral bending stiffness K can be calculated. b and axial tension and compression stiffness K p The size of the ribs 5321 is designed according to the decoupling degree. When the decoupling degree γ is constant, the more the number of ribs 5321 is, the greater the lateral bending stiffness K of the force transmission shaft 53 is. b and axial tension and compression stiffness K p When the size of the ribs 5321 is determined, the number of the ribs 5321 depends on the diameter of the force transmission shaft 53 and the gap size between different ribs 5321, and the gap size depends on the processing technology. When the processing technology allows, the smaller the gap between the ribs 5321, the more the number of ribs 5321, and the lateral bending stiffness K of the force transmission shaft 53. b and axial tension and compression stiffness K p The larger it is, the higher the structural rigidity of the measuring device.

[0081] In the present invention, the lateral bending stiffness K of the force transmission shaft 53 is b Less than or equal to axial tension and compression stiffness K p 1%.

[0082] Among them, K b and K p They can be calculated by the following formulas:

[0083]

[0084]

[0085]

[0086] γ represents the degree of decoupling;

[0087] L represents the length of the rib 5321 of the force transmission shaft 53;

[0088] A n represents the cross-sectional area of ​​a single rib 5321;

[0089] n represents the number of ribs;

[0090] E represents the elastic modulus of the material of the power transmission shaft 53 .

[0091] According to a force measurement device for shrouded turbine blades of the present invention, when the friction block 7 is subjected to a three-way contact force load, the force load is transmitted to the first force transmission structure base 2, the second force transmission structure base 3 and the third force transmission structure base 4 respectively through the force transmission structure 5, and the three-way orthogonal force transmission structures 5 respectively transmit forces in different directions, and the magnitude of the transmitted axial force load is measured by the force sensor 52. Since the friction block base 6 connects the three-way orthogonal force transmission structures 5 together, in order to avoid the influence of the force dimension coupling on the force measurement result, the specific force transmission shaft 53 of the present invention is used as the core part of the force transmission structure 5. The two ends of the force transmission shaft 53 are respectively connected to the connecting shaft 54 ​​and the force sensor 52, and the connection method can be designed according to the size of the connecting shaft 54 ​​and the force sensor 52. The second part 532 of the force transmission shaft 53 adopts a special structural design, with the rib 5321 as a flexible hinge structure. The axial dimension of the rib 5321 is larger than the cross-sectional dimension, thereby ensuring that the transverse bending stiffness of the rib 5321 is much lower than the axial tensile and compressive stiffness, thereby ensuring that the axial tensile and compressive stiffness K of the force transmission shaft 53 composed of the rib 5321 is p Much higher than the lateral bending stiffness K b .

[0092] According to the mechanical property testing device for the blade shroud contact interface of the aircraft engine turbine blade of the present invention, the three force transmission structures 5 of the force measuring assembly are arranged according to the first coordinate system x1-y1-z1, see Fig.14 , Fig.15 , if the load f1 is applied according to the first coordinate system (x1-y1-z1), then:

[0093]

[0094] Apply load f in the x1 direction x1 For example, when the friction block 7 is deformed in the x1 direction, the force transmission structure 5 in the x1 direction is axially deformed, and the other two force transmission structures 5 are transversely bent and deformed. According to the deformation coordination condition, the deformation of the friction block 7 under load along the three coordinate axes of the first coordinate system x1-y1-z1 can be expressed as:

[0095]

[0096]

[0097]

[0098] Defined in the first coordinate system x1-y1-z1, the support reaction force provided by the force transmission structure 5 to the friction block 7 along the x1 direction can be expressed as F x,x1 、F x,y1 and F x,z1Similarly, the support reaction force provided by the force transmission structure 5 in other directions to the friction block 7 can be obtained, and according to the force balance condition, the relationship between the support reaction force F1 and the load f1 can be obtained as follows:

[0099]

[0100] Calculate the results of the support reaction force when there is only load f1, and add them together to get the support reaction force matrix F1

[0101]

[0102] The loads f in different directions measured by the force sensors 52 of the three force transmission structures 5 are: 1t for

[0103]

[0104] At this time, the relative error can be expressed as:

[0105]

[0106]

[0107]

[0108] Obviously, the error level is related to the load level, which can lead to uncontrollable large relative errors, for example, when f z1 When it is much smaller than the other two directions, the relative error e z1 will be infinitely magnified.

[0109] The schematic diagram of the setting method of the second coordinate system x2-y2-z2 is as follows Fig.16 and Fig.17 The second coordinate system x2-y2-z2 takes the plane where the installation plane 11 is located as the y2-z2 plane and the direction perpendicular to the installation plane 11 as the x2 direction.

[0110] When the load f2 is applied according to the second coordinate system x2-y2-z2, the load can be equivalent to f in the first coordinate system x1-y1-z1. 1,2 for:

[0111]

[0112]

[0113] that is:

[0114]

[0115] The load f in the first coordinate system measured by the three force transmission structures 5 arranged in the first coordinate system is1t,2 for:

[0116]

[0117] The load f 1t,2 Transform back to the second coordinate system to obtain the actual measurement result f 2t,2 ,

[0118]

[0119] The actual measurement result f 2t,2 The relative error with load f2 can be expressed as:

[0120]

[0121]

[0122]

[0123] At this time, the relative error is only related to the decoupling degree γ, and has nothing to do with the contact force level. That is, applying the load according to the second coordinate system and measuring the load level according to the first coordinate system can achieve decoupling between the relative error of the contact force measurement result and the contact force level, so that the accuracy of the force measuring assembly is only related to the decoupling degree of the force transmission shaft 53.

[0124] Furthermore, there is an angle α between the friction block contact surface 711 and the x2-y2 plane of the second coordinate system. The plane where the friction block contact surface 711 is located is the x3-y3 plane, and the direction perpendicular to the friction block contact surface 711 is the z3 direction to construct a third coordinate system x3-y3-z3. The schematic diagram of the third coordinate system is as follows: Fig.19 shown.

[0125] The relationship between the third coordinate system established on the friction block contact surface 711 and the second coordinate system can be expressed as follows: the third coordinate system is obtained by rotating the second coordinate system around the x2 axis by α degrees. Since in the second coordinate system, e y2 and e z2 equal, therefore, the contact force measurement accuracy when applying load in the third coordinate system is the same as that in the second coordinate system.

[0126] Through this setting, for blade crown contact surfaces with different angles, measurement can be achieved by changing the angle of the friction block contact surface and the corresponding third coordinate system without affecting the measurement accuracy, so that the force measuring device for crowned turbine blades of the present invention can better adapt to the contour shape of the crowned worm wheel blades.

[0127] A force measuring device for a shrouded turbine blade of the present invention reduces the ratio of the lateral bending stiffness to the axial tension and compression stiffness, thereby reducing the ratio of the lateral deformation sharing load in the non-force measuring direction to the load transmitted in the force measuring direction, thereby achieving control of the measurement accuracy by changing the decoupling degree by changing the structural parameters.

[0128] On this basis, in order to reduce the influence of the contact force level between different directions on the relative error, the present invention adopts a rectangular first coordinate system to arrange the force transmission structure. There is a linear transformation relationship between the rectangular coordinate system and the second coordinate system with the plane where the installation plane 11 is located as the y2-z2 plane and the direction perpendicular to the installation plane 11 as the x2 direction. At the same time, considering that there is an angle α between the friction block contact surface 711 and the x2-y2 plane of the second coordinate system, therefore, a third coordinate system is established based on the friction block contact surface 711 and the x2 direction of the second coordinate system. There is a linear transformation relationship between the third coordinate system and the first coordinate system and the second coordinate system. The third coordinate system is used as the contact surface coordinate system, the first coordinate system is used to arrange the force transmission structure and measure the contact force. The coupling effect between the force dimensions in different directions is only related to the decoupling degree of the force transmission axis 53, but has nothing to do with the size of the contact force.

[0129] The linear transformation relationship between the first coordinate system, the second coordinate system, and the third coordinate system is related to the way the coordinate system direction is defined. The difference in this definition method includes the difference in definition direction and naming, and the difference in positive direction. The linear transformation relationship obtained will change accordingly. This change includes the transformation between rows and columns and the transformation between positive and negative signs. Figure 14-17 as well as Fig.19 In the coordinate system definition method provided in this embodiment, the linear transformation relationship between the three coordinate systems satisfies the following formula:

[0130]

[0131]

[0132]

[0133]

[0134] When a force measuring device for a shrouded turbine blade of the present invention is used for contact force measurement, the friction pair contacts the friction block 7 to transmit contact force, and the force sensors 52 in three orthogonal directions measure the forces along the three coordinate axes in the first coordinate system. By utilizing the transformation relationship between the coordinate systems, the measurement results of the contact forces in the second coordinate system and the third coordinate system can be obtained, and finally the measurement results of the contact force on the contact surface of the friction block 7 in the third coordinate system can be obtained.

[0135] Compared with the prior art, the force measurement device for crowned turbine blades provided in this embodiment effectively reduces the influence of force-dimensional coupling in three-dimensional contact force measurement by adopting a force transmission shaft 53 designed with a flexible hinge structure, thereby improving the measurement accuracy; by adopting a force transmission structure 5 arranged orthogonally in three directions according to a first coordinate system and measuring the contact force, and defining the friction block contact surface 711 by a third coordinate system, the influence of the contact force level on the relative error of the three-dimensional contact force measurement is effectively eliminated, wherein the introduction of the third coordinate system enables the measuring device to realize the measurement of the contact surfaces of crowned turbine blades with different meshing angles. Specifically, friction blocks with different angles can be designed for different meshing angles. By adopting the arrangement of the force transmission structure 5 and connecting them with the friction block base 6, the friction block 7 is extended, ensuring the accessibility of the friction block 7, so as to provide a friction pair static part for small-sized structures such as the blade crown contact surface of the turbine blade of an aircraft engine, so as to measure the contact force of the contact interface; the three-way force transmission structure 5 is connected together through the friction block base 6 to provide stiffness for the friction block 7, thereby providing sufficient structural stiffness for the friction block 7 while ensuring the small size and accessibility of the friction block 7. By moving and adjusting the force measuring assembly through the slide rail and the slider, the contact surface gap or interference problem caused by assembly positioning and processing errors is avoided, thereby improving the measurement accuracy.

[0136] Example 2

[0137] On the basis of Example 1, the present invention further relates to a method for testing the mechanical properties of the blade shroud contact interface of an aircraft engine turbine blade, using a force measuring device for a shrouded turbine blade of Example 1.

[0138] The test method includes the following steps:

[0139] S1: Fix the blade root of the aircraft engine turbine blade A on the fixture of the test bench;

[0140] S2: installing a force measuring device for a shrouded turbine blade according to Example 1 at a corresponding position on a test bench;

[0141] S3: making the friction block contact surface 711 of the friction block 7 abut against the contact surface of the blade crown of the aircraft engine turbine blade, and then fixing the force measuring assembly on the mounting base 1;

[0142] S4: applying excitation to the aircraft engine turbine blade A and recording the data fed back by the force sensor 52;

[0143] S5: Calculate the data to analyze and obtain the mechanical characteristic parameters of the contact interface of the aircraft engine turbine blade A.

[0144] Furthermore, step S2 specifically includes the following steps:

[0145] S21: Install a set of force measuring components on the mounting base 1;

[0146] S22: Fix the mounting base 1 to a corresponding position on the test bench.

[0147] In step S21, the positioning platform 21 of the first force transmission structure base 2 is first inserted into the first flat key groove 111, and then the slide rail 8 is fixed to the slide rail mounting groove 115, and the two sliders 9 are respectively fixedly installed on the slider mounting surfaces of the second force transmission structure base 3 and the third force transmission structure base 4, and the sliders 9 of the second force transmission structure base 3 and the third force transmission structure base 4 are respectively inserted into the slide rails 8 in the two slide rail mounting grooves 115.

[0148] Next, the three assembled force transmission structures 5 are fixed to the installation inclined surfaces of the three force transmission structure bases respectively, the positions of the three force transmission structure bases are adjusted, and finally the friction block base 6 with the friction block 7 fixed thereon is installed to the top of the three force transmission structures 5 .

[0149] In step S3, the data fed back by the force sensor 52 is between 0.1N and 0.2N. When this condition is met, it indicates that the contact surface between the friction block 7 and the blade crown A is in good contact, and is neither too loose to obtain valid data nor too tight to obtain inaccurate data. Then, the first force transmission structure base 2 is fixed to the mounting plane 11 by means of the countersunk nail and the first countersunk hole 24; the second force transmission structure base 3 is fixed to one of the first group of second flat key slots 112 by means of the flat key 10 and the countersunk screw, and the third force transmission structure base 4 is fixed to one of the second group of second flat key slots 112.

[0150] Further, in step S4, the excitation applied to the aircraft engine turbine blade A is a vibration excitation, which is applied along the direction of the coordinate axis of the third coordinate system; the force data f measured by the force sensor 52 of the three force transmission structures 5 are recorded. 1t for

[0151]

[0152] See also Figure 1-Figure 2 First, the blade root position of the aircraft engine turbine blade A is fixed on the fixture of the test bench (not shown in the figure), and then a force measurement device for a shrouded turbine blade of Example 1 is installed at the corresponding position on the test bench according to the scene requirements. The test device of the present invention is arranged at the blade shroud position of the aircraft engine turbine blade A.

[0153] The friction block 7 is in contact with the blade crown contact surface of the aircraft engine turbine blade A. Specifically, the platform portion 61 of the friction block base 6 is perpendicular to the blade height direction of the aircraft engine turbine blade A. The mounting base 1 is fixedly mounted on the test bench through the bolt hole 121 and the mounting groove 122. The specific connection method can be determined according to the structure of the test bench and does not affect the application effect.

[0154] In step S5, the data is calculated to analyze and obtain the mechanical characteristic parameters of the contact interface of the aircraft engine turbine blade 11. Specifically, the force data f measured by the force sensor 52 is 1t The linear coordinate transformation of the force is carried out to the third coordinate system, thereby obtaining the friction contact force f on the friction block contact surface 711: c

[0155]

[0156] f c =A2A1f 1t

[0157]

[0158]

[0159] Example 3

[0160] On the basis of Example 2, in step S21 of Example 3, two groups of force measuring components are installed on the installation base 1.

[0161] The installation steps are similar to those for a set of force measuring components. The structure after assembly is as follows: Figure 21-23 shown.

[0162] The two groups of force measuring components respectively measure the contact forces of the two contact surfaces of the blade crown of the aircraft engine turbine blade A. When the aircraft engine turbine blade A vibrates under the action of excitation, relative movement will occur between the friction block 7 and the contact surface of the aircraft engine turbine blade A, thereby generating contact force. The contact force is measured by the force sensor 52 of the test device of the present invention, thereby obtaining the contact force signal of the blade crown contact surface of the aircraft engine turbine blade A when it vibrates under excitation, thereby analyzing the mechanical properties of its contact interface.

[0163] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A force measuring device for a shrouded turbine blade, characterized in that: It comprises a mounting base and at least one force measuring assembly; the force measuring assembly is adjustably arranged on the mounting base; Wherein, the mounting base includes a mounting plane extending in a vertical direction; The force measuring assembly comprises a first force transmission structure base, a second force transmission structure base, a third force transmission structure base, three force transmission structures, a friction block base and a friction block; wherein the first force transmission structure base, the second force transmission structure base and the third force transmission structure base are respectively arranged on the installation plane in an adjustable manner, one end of the three force transmission structures are respectively fixedly connected to the first force transmission structure base, the second force transmission structure base or the third force transmission structure base, and the three force transmission structures are orthogonal to each other; the other ends of the three force transmission structures are fixedly connected to the friction block base; the friction block base comprises a platform portion, the friction block is fixedly arranged on the platform portion, and the platform portion is parallel to the installation plane and spaced a distance from each other; The three force transmission structures are arranged according to a first rectangular coordinate system (x1-y1-z1), and the three force transmission structures extend along the directions of x1, y1, and z1, respectively; the following linear transformation relationship exists between the first rectangular coordinate system (x1-y1-z1) and a second rectangular coordinate system (x2-y2-z2) with the installation plane as the y2-z2 plane and the normal direction of the installation plane as the x2 direction:

2. A force measuring device for a shrouded turbine blade according to claim 1, characterized in that: A first flat keyway and two slide rail mounting grooves are provided on the mounting plane; the first flat keyway and the two slide rail mounting grooves are arranged parallel to each other and spaced apart; a slide rail is fixedly arranged in the slide rail mounting groove; a positioning platform is provided at the bottom of the first force transmission structure base, the positioning platform is arranged in the first flat keyway and can reciprocate relative to the first flat keyway; sliders are provided at the bottom of the second force transmission structure base and the third force transmission structure base, and the sliders are arranged on the slide rails one by one.

3. A force measuring device for a shrouded turbine blade according to claim 2, characterized in that: Two groups of second flat key grooves are also provided on the installation plane, and the two groups of second flat key grooves are arranged in one-to-one correspondence with the two slide rail installation grooves; the first flat key groove and the two groups of second flat key grooves are both equipped with first threaded holes; the bottoms of the second force transmission structure base and the third force transmission structure base are both provided with third flat key grooves, and the force measuring device also includes a flat key, which is inserted into the second flat key groove and the third flat key groove; the first force transmission structure base, the second force transmission structure base and the third force transmission structure base are respectively fixed to the installation plane by fasteners through corresponding first threaded holes.

4. A force measuring device for a shrouded turbine blade according to claim 1, characterized in that: The force transmission structure includes a force sensor adapter block, a force sensor, a force transmission shaft and a connecting shaft connected in sequence; the force sensor adapter block is fixedly connected to the first force transmission structure base, the second force transmission structure base or the third force transmission structure base; the connecting shaft is fixedly connected to the friction block base.

5. A force measuring device for a shrouded turbine blade according to claim 4, characterized in that: The transverse bending stiffness K of the force transmission axis b Less than or equal to axial tension and compression stiffness K p 1%.

6. A force measuring device for a shrouded turbine blade according to claim 1, characterized in that: The friction block base further includes three support rod portions, which extend outward from the edge of the friction block base. The three support rod portions are orthogonal to each other and are evenly distributed circumferentially relative to the center of the friction block base.

7. A force measuring device for a shrouded turbine blade according to claim 6, characterized in that: The three force transmission structures are respectively fixedly connected to one of the three support rod parts.

8. A force measuring device for a shrouded turbine blade according to claim 7, characterized in that: The friction block comprises a friction block mounting end and a friction block friction end, wherein the friction block mounting end is fixedly arranged in the middle of the friction block base, and the friction block friction end has a friction block contact surface, and the friction block contact surface is located on the side of the friction block friction end.

9. A force measuring device for a shrouded turbine blade according to claim 8, characterized in that: The friction block coincides with the central axis of the friction block base, the intersection of the central axes of the three support rods is located on the friction block contact surface, and there is an angle α between the friction block contact surface and the horizontal plane. The plane where the friction block contact surface is located is the x3-y3 plane, and the direction perpendicular to the friction block contact surface is the z3 direction to construct a third coordinate system x3-y3-z3, which has the following linear transformation relationship with the second coordinate system:

10. A method for measuring force on a shrouded turbine blade, characterized in that: Use of a force measuring device for a shrouded turbine blade according to any one of claims 1 to 9.

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