Aero-engine dovetail type tenon blade measuring method based on mathematical model

Abstract

The invention discloses an aero-engine dovetail type tenon blade measuring method based on a digital model, and provides a measuring clamp which comprises a bottom plate and a plurality of clamping tools which are arranged on the upper end face of the bottom plate and are regularly arranged at intervals. Each clamping tool is used for clamping and positioning a dovetail tenon of a dovetail tenon blade to be measured, and the clamping and positioning size of each clamping tool is adjustable; a to-be-measured dovetail-type tenon blade is installed on each clamping tool, and the clamping tools are used for clamping and positioning the dovetail-type tenon of the to-be-measured dovetail-type tenon blade; a three-coordinate measuring method is adopted, the to-be-measured dovetail-shaped tenon blade on each clamping tool is measured successively, and after the to-be-measured dovetail-shaped tenon blade on the current clamping tool is measured, a new to-be-measured dovetail-shaped tenon blade is replaced to wait for next measurement. The cost can be reduced, and the measurement efficiency can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of measuring compressor blades of aircraft engines, and in particular relates to a method for measuring dovetail tenon blades of aircraft engines based on digital modeling. Background Art

[0002] Aero-engine rotor blades are usually installed and positioned using a dovetail tenon structure, which can effectively transmit torque and withstand the huge centrifugal force generated by high-speed rotation. The dovetail type is used as a measurement reference, but due to its unique geometric shape and complex contour, the positioning stability is relatively poor, which brings difficulties to accurate measurement.

[0003] The traditional measurement method relies on designing and manufacturing a set of special three-dimensional measurement fixtures for each type of blade. The function of these fixtures is to convert the dovetail type, a difficult-to-measure reference, into the fixture's own measurement system, thereby achieving the measurement of the blade size. Although this method meets the measurement accuracy requirements to a certain extent, it has cost and efficiency issues. Specifically, first, each set of fixtures needs to be customized according to the specific size and shape of the blade, which not only increases the complexity of the design work, but also prolongs the cycle from design to production of new blades. Secondly, after completing the measurement of a blade, the traditional measurement method needs to stop the machine for loading and unloading and re-clamping the blade, which greatly affects the measurement efficiency. In addition, with the continuous updating and iteration of aircraft engine models, each new type of blade needs to be equipped with a corresponding measurement fixture, which further increases the cost of storage and maintenance of the fixture. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for measuring dovetail tenon blades of an aero-engine based on digital modeling, which can reduce costs and improve measurement efficiency.

[0005] In order to solve the above technical problems, the present invention is implemented by the following technical solutions: A method for measuring a dovetail tenon blade of an aero-engine based on a digital model, comprising: A measuring fixture is provided, the measuring fixture comprising a bottom plate and a plurality of clamping fixtures arranged on the upper end surface of the bottom plate and arranged at regular intervals, each of the clamping fixtures is used to clamp and position the dovetail tenon of the dovetail tenon blade to be measured, and the clamping and positioning size of each of the clamping fixtures is adjustable; A dovetail tenon blade to be measured is installed on each clamping fixture, and the dovetail tenon of the dovetail tenon blade to be measured is clamped and positioned by using the clamping fixture; The three-coordinate measurement method is used to measure the dovetail tenon blade to be measured on each clamping fixture one by one, and after measuring the dovetail tenon blade to be measured on the current clamping fixture, a new dovetail tenon blade to be measured is replaced and waits for the next measurement.

[0006] Furthermore, the three-coordinate measurement method is used to measure the dovetail tenon blades to be measured on each clamping fixture one by one, specifically: For each clamping fixture, a three-coordinate measurement coordinate system is pre-established; According to the preset measurement sequence, in the three-coordinate measurement coordinate system corresponding to each clamping fixture, a three-coordinate measuring machine is used to perform cyclic measurement on the dovetail tenon blade to be measured on each clamping fixture.

[0007] Furthermore, for each clamping fixture, a three-coordinate measurement coordinate system is pre-established, specifically: Select any clamping fixture and establish a three-coordinate measurement rough positioning coordinate system for the clamping fixture; Taking the three-coordinate measurement rough positioning coordinate system of the clamping fixture as a reference and combining the positional relationship between the other clamping fixtures and the clamping fixture, establish the three-coordinate measurement rough positioning coordinate system of the other clamping fixtures; During measurement, the blade digital model coordinate system is aligned with the three-coordinate measurement coarse positioning coordinate system, the theoretical parameters of the measurement points are obtained from the blade digital model, and the three-coordinate measurement coordinate system is established through the coordinate system fitting method.

[0008] Furthermore, the preset measurement sequence specifically includes: According to the number of dovetail tenon blades to be measured, the number of measurements and the starting sequence number of the dovetail tenon blades to be measured are set; Select any clamping fixture to start measuring, set the starting number of measurements to 1 and the starting sequence number of the dovetail tenon blade to be measured to 1, after measuring the dovetail tenon blade to be measured on the clamping fixture, add 1 to the measurement number, add 1 to the blade sequence number, and measure the dovetail tenon blade to be measured on the next clamping fixture; The dovetail tenon blades to be measured on each clamping fixture are measured in a cycle in sequence until the number of measurements reaches the measurement times.

[0009] Furthermore, the clamping fixture includes a positioning column, a first positioning block, a second positioning block and a third positioning block, the positioning column is vertically installed on the upper end surface of the base plate, and the upper end surface of the positioning column is used to position the bottom surface of the dovetail tenon; the first positioning block is fixed to a position of the upper end surface of the positioning column close to the first side, and the second positioning block is connected to a position opposite to the first positioning block through a displacement adjustment component, and the displacement adjustment component can adjust the second positioning block away from or close to the first positioning block, and the surfaces of the first positioning block and the second positioning block facing each other are used to position the two end surfaces of the dovetail tenon; the third positioning block is fixed to a position of the upper end surface of the positioning column close to the second side, the first side is perpendicular to the second side, and the third positioning block is used to position the working surface of the dovetail tenon.

[0010] Furthermore, the displacement adjustment component includes a sliding hole and a slider slidably arranged in the sliding hole, the sliding hole is opened through the first side and the third side of the positioning column, the first side is opposite to the third side, and the second positioning block is fixed on the slider.

[0011] Furthermore, the displacement adjustment assembly also includes a pad, a screw and an elastic member, the pad is fixed to the first side of the positioning column, a through hole is formed on the pad, a threaded hole is formed on an end surface of the slider facing the pad, one end of the screw is movable through the through hole and is threadedly connected to the threaded hole, the elastic member is sleeved on the screw, and one end of the elastic member abuts against an end surface of the slider facing the pad, and the other end of the elastic member abuts against the pad.

[0012] Furthermore, the elastic member is a spring.

[0013] Furthermore, the positioning column is detachably connected to the upper end surface of the base plate.

[0014] Furthermore, the positioning column is detachably connected to the upper end surface of the base plate via a positioning pin and a bolt.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention provides a method for measuring dovetail tenon blades of aircraft engines based on digital modeling. By adopting a clamping fixture with adjustable clamping and positioning dimensions, universal clamping of dovetail tenon blades of different sizes is realized. A set of measuring fixtures can meet the measurement requirements of various types of blades, thereby avoiding the need to design and manufacture special fixtures for each new blade, and reducing the design, manufacturing and subsequent storage costs of the fixture. The present invention adopts the design of multiple clamping fixtures, so that when measuring a blade on a clamping fixture, other clamping fixtures can prepare the next blade to be measured, thereby realizing seamless connection of blade measurement, and blades can be measured continuously on multiple clamping fixtures without stopping and waiting, thereby greatly improving measurement efficiency and realizing an efficient operation mode of "one person and multiple machines". With the continuous updating and iteration of aircraft engine models, traditional methods need to continuously design and manufacture new measuring fixtures to adapt to new blades. The present invention can easily cope with the measurement requirements of blades of different models and sizes through adjustable clamping fixtures and flexible measurement procedures, without the need to frequently replace fixtures, thereby enhancing the flexibility and adaptability of measurement. In summary, the present invention effectively solves the problems of high cost and low efficiency in traditional measurement methods, and provides a new efficient, economical and flexible method for measuring aircraft engine blades.

[0016] Furthermore, the positioning accuracy is ensured by the design of the blade number simulation combined coordinate system and the self-circulation of the measurement program.

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the specific implementation modes of the present invention, the drawings required for use in the description of the specific implementation modes will be briefly introduced below. Obviously, the drawings described below are some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a flow chart of a method for measuring an aircraft engine dovetail tenon blade based on digital modeling according to an embodiment of the present invention; Figure 2 It is a schematic diagram of the front view of the measuring fixture structure according to an embodiment of the present invention; Figure 3 It is a left view of the measuring fixture structure according to an embodiment of the present invention; Figure 4 Schematic diagram of different viewing angles of the positioning column in the embodiment of the present invention; Figure 5 Schematic diagram of the second positioning block and the slider at different viewing angles in an embodiment of the present invention; Figure 6 Schematic diagram of a pad at different viewing angles in an embodiment of the present invention; Figure 7 Schematic diagram of different viewing angles of the third positioning block in an embodiment of the present invention; Figure 8a This is the front view of the dovetail tenon; Figure 8b It is a schematic diagram of the relationship between the blade coordinate system and the tenon; Fig. 9 It is a flow chart of the measurement procedure of an embodiment of the present invention.

[0020] In the figure: 1-base plate; 2-positioning column; 3-first positioning block; 4-second positioning block; 5-third positioning block; 6-displacement adjustment assembly; 60-slider; 600-threaded hole; 61-pad; 62-screw; 7-positioning pin; 8-bolt. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Combination Figures 1 to 8b As shown, an embodiment of the present invention provides a method for measuring an aircraft engine dovetail tenon blade based on digital modeling, mainly to achieve cost reduction and improvement of measurement efficiency by optimizing the design of the measurement fixture and the measurement process. The measurement method includes the following steps: S1. Provide a measuring fixture, which includes a base plate 1 and a plurality of clamping fixtures arranged on the upper end surface of the base plate 1 and arranged at regular intervals, each clamping fixture is used to clamp and position the dovetail tenon of a dovetail tenon blade to be measured, and the clamping and positioning size of each clamping fixture is adjustable.

[0023] Specifically, the measuring fixture is mainly composed of a base plate 1 and a plurality of clamping fixtures. The base plate 1 serves as the basis of the entire fixture to ensure the stability of the fixture. On the upper end surface of the base plate 1, a plurality of clamping fixtures are arranged at regular intervals. These clamping fixtures are used to clamp and position the dovetail tenon blades to be measured. The design of each clamping fixture takes into account the geometric shape and contour characteristics of the dovetail tenon to ensure that it can clamp the blade tightly and stably. The clamping and positioning dimensions of each clamping fixture are adjustable. No matter how the size or shape of the blade changes, it can be adapted by adjusting the clamping fixture, which greatly enhances the versatility of the fixture.

[0024] S2. Install a dovetail tenon blade to be measured on each clamping fixture, and use the clamping fixture to clamp and position the dovetail tenon of the dovetail tenon blade to be measured.

[0025] That is to say, before measuring, the dovetail blade to be measured needs to be mounted on each clamping fixture. This is achieved through the clamping mechanism of the clamping fixture, ensuring that the blade can be stably positioned on the fixture. Since the clamping and positioning dimensions of the clamping fixture are adjustable, it can adapt to blades of different sizes and shapes, without the need to design and manufacture dedicated fixtures for each type of blade.

[0026] S3. Use the three-coordinate measurement method to measure the dovetail tenon blade to be measured on each clamping fixture one by one, and after measuring the dovetail tenon blade to be measured on the current clamping fixture, replace the new dovetail tenon blade to be measured and wait for the next measurement.

[0027] According to the above steps, the blades on each clamping fixture are measured in turn until all the blades to be measured are measured.

[0028] That is to say, after the blade is stably positioned by the clamping fixture, the blade is measured by a three-dimensional coordinate measuring machine. It should be understood that the three-dimensional coordinate measurement method is a high-precision and high-efficiency measurement method that can accurately obtain the size and shape information of the blade. In the specific implementation, the blades on each clamping fixture are measured one by one. In order to improve the measurement efficiency, after measuring the blade on the current clamping fixture, the new blade to be measured is immediately replaced and wait for the next measurement. In this way, there is no need to stop the machine for loading and unloading and re-clamping of the blade during the measurement process, which greatly shortens the measurement cycle.

[0029] For example, a high-precision coordinate measuring machine (CMM) is used to measure the blade on the fixture. Before measurement, the CMM needs to be calibrated to ensure the accuracy of the measurement result.

[0030] In more detail, by constructing a digital model of the blade, accurate prediction and simulation of the blade dimensions can be achieved. During the measurement process, the actual measurement results can be compared with the digital model, so that potential errors can be discovered and corrected in a timely manner.

[0031] Since the measuring fixture of the present invention is universal, the number and types of fixtures can be greatly reduced, which not only reduces the storage and maintenance costs of the fixtures, but also improves the utilization rate and turnover rate of the fixtures. In practical applications, it is only necessary to adjust and configure the clamping fixture according to actual needs to meet the measurement requirements of different types of blades. The digital model-based dovetail tenon blade measurement method for aircraft engines provided by the present invention has the advantages of low cost, high efficiency, and strong versatility. By applying the method of the present invention, the measurement accuracy and efficiency of aircraft engine rotor blades can be greatly improved.

[0032] In one achievable manner, a three-dimensional coordinate measuring machine is used to measure each dovetail tenon blade to be measured on each clamping fixture one by one, specifically: a. For each clamping fixture, a three-coordinate measurement coordinate system is established in advance.

[0033] Specifically, for each clamping fixture, before measuring, a three-coordinate measurement coordinate system needs to be established in advance. The specific method is to select one or more fixed reference points or reference surfaces on each clamping fixture; then, use a three-coordinate measuring machine to measure these reference points or reference surfaces, and establish a corresponding three-coordinate measurement coordinate system based on the measurement results. This coordinate system will serve as the benchmark for subsequent measurements to ensure that all measurement data can be compared and analyzed in a unified coordinate system.

[0034] b. According to the preset measurement sequence, in the three-coordinate measurement coordinate system corresponding to each clamping fixture, use the three-coordinate measuring machine to perform cyclic measurement on the dovetail tenon blade to be measured on each clamping fixture.

[0035] That is to say, after the three-dimensional coordinate measurement coordinate system is established and the measurement sequence is preset, the three-dimensional coordinate measuring machine is used to perform cyclic measurement on each dovetail tenon blade to be measured on the clamping fixture. The three-dimensional coordinate measuring machine can automatically and accurately obtain the size and shape information of the blade.

[0036] In one achievable manner, a three-coordinate measurement coordinate system is pre-established for each clamping fixture, specifically: a. Select any clamping fixture and establish the three-dimensional measurement rough positioning coordinate system of the clamping fixture. In other words, among all the clamping fixtures, select one as the reference clamping fixture, and this selection can be arbitrary.

[0037] b. Taking the three-coordinate measurement rough positioning coordinate system of the clamping fixture as the reference, combined with the positional relationship between the remaining clamping fixtures and the clamping fixture, establish the three-coordinate measurement rough positioning coordinate system of the remaining clamping fixtures; c. During measurement, align the blade digital model coordinate system with the three-coordinate measurement coarse positioning coordinate system, obtain the theoretical parameters of the measurement points from the blade digital model, and establish the three-coordinate measurement coordinate system through the coordinate system fitting method.

[0038] In one achievable manner, the preset measurement sequence specifically includes: a. According to the number of dovetail blades to be measured, set the number of measurements and the starting sequence number of the dovetail blades to be measured.

[0039] That is, according to the total number of dovetail blades to be measured, the total number of measurements is set, which is equal to the total number of blades to ensure that each blade can be measured. At the same time, the starting sequence number of the dovetail blade to be measured is set, which must be the same as the sequence number of the first blade to be measured to ensure that the output sequence number is correct.

[0040] b. Select any clamping fixture to start measuring, set the starting number of measurements to 1 and the starting sequence number of the dovetail tenon blade to be measured to 1. After measuring the dovetail tenon blade to be measured on the clamping fixture, add 1 to the measurement number and the blade sequence number, save the conclusion and measure the dovetail tenon blade to be measured on the next clamping fixture.

[0041] That is to say, any clamping fixture is selected as the starting measurement point. The selection can be arbitrary. Then, the starting number of the measurement quantity is set to 1, and the starting sequence number of the dovetail tenon blade to be measured is 1, which means that the first blade with sequence number 1 is measured. After selecting the starting clamping fixture and initializing the measurement count, the measurement is started. The three-coordinate measuring machine is used to measure the dovetail tenon blade to be measured on the starting clamping fixture according to the pre-established three-coordinate measurement coordinate system. After the measurement is completed, the measurement quantity is increased by 1, and the blade sequence number is 1, indicating that one blade has been measured. Then the conclusion is output, and the measurement of the dovetail tenon blade to be measured on the next clamping fixture is carried out, and the above measurement steps are repeated. After each measurement is completed, the measurement count and the blade sequence number are updated to ensure that the measurement of each blade is recorded.

[0042] c. Measure the dovetail tenon blades to be measured on each clamping fixture in turn in a cycle until the number of measurements reaches the measurement times, that is, all the blades to be measured have been measured and the measurement process is completed.

[0043] In one implementable manner, the clamping fixture includes a positioning column 2, a first positioning block 3, a second positioning block 4 and a third positioning block 5. The positioning column 2 is vertically installed on the upper end surface of the base plate 1, and the upper end surface of the positioning column 2 is used to position the bottom surface of the dovetail tenon; the first positioning block 3 is fixed to a position of the upper end surface of the positioning column 2 close to the first side, and the second positioning block 4 is connected to a position opposite to the first positioning block 3 through a displacement adjustment component 6. The displacement adjustment component 6 can adjust the second positioning block 4 away from or close to the first positioning block 3. The surfaces of the first positioning block 3 and the second positioning block 4 facing each other are used to position the two end surfaces of the dovetail tenon; the third positioning block 5 is fixed to a position of the upper end surface of the positioning column 2 close to the second side, the first side is perpendicular to the second side, and the third positioning block 5 is used to position the working surface of the dovetail tenon.

[0044] Specifically, the positioning column 2 is vertically mounted on the upper end surface of the base plate 1, and its design purpose is to provide a stable support and positioning reference for the bottom surface of the dovetail tenon. The upper end surface of the positioning column 2 is precisely machined to ensure good contact and positioning accuracy with the bottom surface of the dovetail tenon. The first positioning block 3 is fixed to the upper end surface of the positioning column 2 near the first side (for example, the right side). The side surface of the first positioning block 3 (that is, the surface facing the second positioning block 4) is precisely machined to locate one end surface of the dovetail tenon to ensure accurate axial positioning of the blade during the measurement process. The second positioning block 4 is connected to the position facing the first positioning block 3 (for example, the left side) through the displacement adjustment component 6. The displacement adjustment component 6 allows the second positioning block 4 to move away from or close to the first positioning block 3 within a certain range to adapt to dovetail tenons of different sizes. The side surface of the second positioning block 4 is also precisely machined to locate the other end surface of the dovetail tenon together with the first positioning block 3. The displacement adjustment component 6 allows the second positioning block 4 to be fine-tuned in the horizontal direction to ensure that the blade is firmly clamped in the correct position during the measurement process. The third positioning block 5 is fixed to the upper end surface of the positioning column 2 near the second side (for example, the front end), and is perpendicular to the first side. The chamfered surface (i.e., the working surface positioning surface) of the third positioning block 5 is used to position the working surface of the dovetail tenon (i.e., the main functional surface of the blade).

[0045] When in use, the position of the second positioning block 4 is adjusted by the displacement adjustment assembly 6 to adapt to the size of the dovetail tenon to be measured. The dovetail tenon to be measured is placed on the upper end surface of the positioning column 2 so that its bottom surface is in close contact with the upper end surface of the positioning column 2. Then, the two end surfaces of the blade are positioned by the side of the first positioning block 3 and the second positioning block 4 to ensure that the blade is accurately positioned in the axial direction. Finally, the working surface of the blade is positioned by the side of the third positioning block 5. After the blade is clamped in the clamping fixture, the blade is measured using a three-dimensional measuring machine according to the preset measurement sequence and measurement procedure. During the measurement process, the three-dimensional measuring machine will automatically record the coordinate data of each measuring point and generate a three-dimensional dimension diagram of the blade.

[0046] In one possible implementation, the displacement adjustment component 6 includes a sliding hole and a slider 60 slidably disposed in the sliding hole. The sliding hole is opened through the first side and the third side of the positioning column 2. The first side is opposite to the third side. The second positioning block 4 is fixed on the slider 60.

[0047] Specifically, the sliding hole is a channel that runs through the first side and the third side of the positioning column 2, which is used to accommodate the sliding of the slider 60. The shape and size of the sliding hole must ensure the smooth sliding of the slider 60 therein. The first side is opposite to the third side, that is, they are located on opposite sides of the positioning column 2, so that the slider 60 can slide in the horizontal direction. The slider 60 is the core component of the displacement adjustment component 6, which is slidably arranged in the sliding hole. The shape and size of the slider 60 match the sliding hole to ensure its smooth sliding in the sliding hole. One end of the slider 60 is fixedly connected to the second positioning block 4, and the other end can be equipped with an adjustment mechanism (such as an adjustment screw, an adjustment handle, etc.) for manually or automatically controlling the sliding of the slider 60 in the sliding hole.

[0048] The working principle of the displacement adjustment component 6 is as follows: when the position of the second positioning block 4 needs to be adjusted to accommodate dovetail tenons of different sizes, this is achieved by controlling the sliding of the slider 60 in the slide hole. Exemplarily, this can be accomplished by manually rotating the adjustment screw, pushing the adjustment handle, and the like. As the slider 60 slides, the second positioning block 4 will also move accordingly, thereby changing the distance between it and the first positioning block 3. By adjusting the sliding distance of the slider 60 in the slide hole, the position of the second positioning block 4 can be precisely controlled. No matter how the size of the dovetail tenon changes, the position of the second positioning block 4 can be adjusted to ensure that it is clamped in the correct position.

[0049] Preferably, the displacement adjustment assembly 6 further includes a pad 61, a screw 62 and an elastic member, the pad 61 is fixed to the first side of the positioning column 2, a through hole is provided on the pad 61, a threaded hole 600 is provided on one end surface of the slider 60 facing the pad 61, one end of the screw 62 is movably passed through the through hole and is threadedly connected with the threaded hole 600, the elastic member is sleeved on the screw 62, and one end of the elastic member abuts against one end surface of the slider 60 facing the pad 61, and the other end of the elastic member abuts against the pad 61. Exemplarily, the screw 62 is a knurled high head screw.

[0050] That is to say, the pad 61 is a flat plate fixed on the first side of the positioning column 2. A through hole is provided on the pad, and the through hole is used to accommodate the screw 62. The pad 61 is designed to provide a support and positioning reference for the screw 62, as well as to provide support for the elastic member, while ensuring that the screw 62 can pass through and be threadedly connected with the threaded hole 600 on the slider 60. The screw 62 is a rod-shaped part with an external thread, one end of which is movable through the through hole on the pad 61 and then threadedly connected with the threaded hole 600 on the slider 60. The screw 62 is designed to achieve threaded connection and separation with the slider 60 by rotating its external threaded part, thereby controlling the sliding distance of the slider 60 in the sliding hole. The elastic member is an elastic element sleeved on the screw 62, such as a spring, a rubber pad, etc. One end of the elastic member is against the end face of the slider 60 facing the pad 61, and the other end is against the pad 61. The elastic member is designed to provide an outward thrust for the slider 60 . When the screw 62 is loosened, the elastic member can push the slider 60 to move away from the pad 61 , thereby achieving the distance adjustment of the second positioning block 4 .

[0051] In this embodiment, the working principle of the displacement adjustment component 6 is as follows: when it is necessary to adjust the second positioning block 4 away from the first positioning block 3, the screw 62 can be rotated counterclockwise (assuming that clockwise rotation is the tightening direction) to gradually withdraw the screw 62 from the threaded hole 600 on the slider 60. At this time, under the elastic force of the elastic member, the slider 60 will be pushed away from the pad 61, that is, the slider 60 will slide outward from the slide hole. As the slider 60 moves, the second positioning block 4 will also move away from the first positioning block 3 accordingly, thereby achieving adaptation to dovetail tenons of different sizes. When it is necessary to adjust the second positioning block 4 close to the first positioning block 3, the screw 62 is rotated clockwise to gradually enter the threaded hole 600 on the slider 60. At this time, the screw 62 will pull the slider 60 to move in the direction close to the pad 61, that is, the slider 60 will slide into the slide hole. As the slider 60 moves, the second positioning block 4 will also move close to the first positioning block 3 accordingly. At the same time, the movement of the slider 60 will compress the elastic member, causing it to produce a certain deformation.

[0052] Preferably, the elastic member is a spring. The spring has good stability and durability. During the displacement adjustment process, the spring can continuously provide a stable thrust to ensure that the slider 60 slides smoothly in the slide hole. Compared with other elastic elements, the spring has the advantages of low cost, easy processing and installation, etc., which is conducive to reducing the manufacturing cost of the displacement adjustment component 6 and improving the overall economic benefits.

[0053] Specifically, the spring is sleeved on the screw 62 and is located between the end surface of the slider 60 facing the pad 61 and the pad 61. When the screw 62 is loosened, the elastic force of the spring can push the slider 60 to move away from the pad 61; and when the screw 62 is tightened, the spring is compressed.

[0054] In one implementation, the positioning column 2 is detachably connected to the upper end surface of the base plate 1. The detachable connection design makes the positioning column 2 and the base plate 1 easy to maintain during long-term use. When the positioning column 2 or the base plate 1 is damaged or worn, the damaged part can be replaced separately without replacing the entire measuring device, thereby reducing maintenance costs.

[0055] Preferably, the positioning column 2 is detachably connected to the upper end surface of the base plate 1 by means of the positioning pin 7 and the bolt 8. The positioning pin 7 is inserted into the pre-designed positioning holes on the positioning column 2 and the base plate 1, thereby achieving preliminary positioning and fixation between the two. The use of the positioning pin 7 helps prevent the positioning column 2 from shifting or rotating during the tightening of the bolt 8, thereby ensuring the accuracy of the measurement. The bolt 8 passes through the threaded hole on the positioning column 2 and cooperates with the threaded hole or nut on the base plate 1, thereby achieving the connection between the positioning column 2 and the base plate 1. Example like Figure 2 As shown, the measuring fixture includes a base plate 1 and four sets of clamping fixtures with the same structure, one set of clamping fixtures is the first station, and the other three are the second, third and fourth stations respectively. The four stations are evenly distributed on the base plate 1 in a matrix manner. The distance between the two outer sides of the clamping fixture and the center line and edge of the base plate is A mm. The bottom surface and two side surfaces of the base plate are used as reference planes, and the verticality of adjacent side surfaces is within 0.01 mm.

[0056] Combination Fig. 9 As shown, in this embodiment, when the three-coordinate measurement method is used for measurement, a measurement program is compiled, which is specifically as follows: (1) Import the mathematical model of the blade to be measured into the measurement software.

[0057] (2) Establishing a three-coordinate measurement coordinate system (2.1) Establish the initial coordinate system Four points are measured on the upper end surface of the positioning column 2 of the clamping fixture at the first station to construct a first plane, which is used as the Z-axis direction of the initial coordinate system of the measured blade; four points are measured on the B reference plane of the measuring fixture to construct a second plane, which is used as the -Y-axis direction of the initial coordinate system; four points are measured on the C reference plane of the measuring fixture to construct a third plane, and an intersection of the first plane, the second plane, and the third plane is constructed as the zero point of the coordinate system.

[0058] (2.2) Establishing the measurement coordinate system Six points are evenly distributed on the reference surfaces on both sides of the tenon of the blade digital model, four points are evenly distributed on the end surface of the tenon, and one point is selected on the edge plate. The measurement coordinate system is established by the iterative method. The termination condition of the iterative coordinate system is that the deviation between the theoretical value and the measured value of the above 11 points in the vector direction is less than 0.002mm. This coordinate system is the final three-coordinate measurement coordinate system of the first workstation.

[0059] (2.3) Establishment of the three-coordinate measurement coordinate system for the remaining workstations The coordinate system of the first station is offset by +2A+Cmm in the X-axis direction to become the initial coordinate system of the second station. The coordinate system of the second station measurement is offset by +2A+Bmm in the Y-axis direction to become the initial coordinate system of the third station. The coordinate system of the third station measurement is offset by -2A-Cmm in the X-axis direction to become the initial coordinate system of the fourth station. The establishment method of the measurement coordinate systems of the other stations is the same as (2.2).

[0060] (3) Determine the number of automatic measurement cycles According to the number of blades to be measured, determine the measurement cycle conditions, and the number of cycles is equal to the number of measured parts. Set the number of measured parts to C1, the measurement start number C2 to 1, and C2+1 after each measurement. Use WHILE / END_WHILE statements to control the loop. When C2>C1, the loop ends.

[0061] (4) Feature measurement and evaluation (4.1) Measurement and evaluation of blade tenon profile with variable tolerance A reasonable probe direction is selected according to the position of the measured feature in the digital model, and three sections are selected on the length of the tenon in the digital model. The tenon contour curve is scanned by open-line scanning on each section. According to the requirements of different tolerance bands, the scanned curve is segmented and evaluated according to different tolerances to obtain the contour value of each tolerance band.

[0062] (4.2) Measurement and evaluation of other features Select the measured characteristics in the digital model, automatically generate measurement statements, select a reasonable probe angle, and use the fitting method and algorithm in the measurement software that meets the requirements of the drawing to measure and evaluate other measured features.

[0063] (4.3) Add safe movement points at appropriate locations in the measurement procedure based on factors such as the structure of the measuring tool and the location of the measurement feature.

[0064] (5) Automatic measurement conclusion output (5.1) Continuous part number output Clamp and measure the test parts according to the sequence number, set the starting sequence number to C3, and after the measurement of the first station is completed, save the measurement report of the blade with sequence number C3, and assign C3=C3+1. Start the measurement of the second station, and after the measurement of the second station is completed, save the measurement conclusion of the blade C3, and assign C3=C3+1, and so on, and the sequence numbers of the parts are accumulated in sequence until the measurement is completed; (5.2) Output of interval part sequence number It is achieved by jointly measuring the number of parts C1 and the starting serial number of parts C3. For example, for serial numbers 1 - 15, 20 - 40, 42 - 80, a total of three measurements are required. a. Set C1 = 15 and C3 = 1, and start the measurement. b. Set C1 = 21 and C3 = 20, and start the measurement. c. Set C1 = 39 and C3 = 42, and start the measurement. Judge whether C2 < C1. If the condition is not met, the program continues to run and measures the blades at the next station. If the condition is met, the program ends; When measuring the blades on a coordinate measuring machine in this embodiment, a four-station and multi-part-number shared measuring fixture can be used to achieve uninterrupted automatic detection of dovetail-shaped parts. By programming different measuring programs, one measuring fixture can be used to measure multiple different types of blades, changing the situation where a set of coordinate measuring fixtures is used for one type of blade, saving the design, manufacturing, and storage costs of the measuring fixtures. When the four-station measuring fixture measures a batch of blades, by programming a cyclic measuring program, the measuring machine continuously and automatically measures the blades at the four stations, saving the time of stopping the machine to wait for loading and unloading the blades and inputting the part serial number after measuring one blade, improving the measuring efficiency, and realizing "one person, multiple machines". This measuring method can be extended to the coordinate measurement of any part.

[0065] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention.

[0066] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0067] In the present invention, unless otherwise clearly specified and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection, an electrical connection, or a communication with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0069] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0070] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for measuring dovetail tenon blades of an aero-engine based on digital model, characterized in that: include: A measuring fixture is provided, the measuring fixture comprising a base plate (1) and a plurality of clamping fixtures arranged on the upper end surface of the base plate (1) and arranged at regular intervals, each of the clamping fixtures being used to clamp and position a dovetail tenon of a dovetail tenon blade to be measured, and the clamping and positioning dimensions of each of the clamping fixtures are adjustable; A dovetail tenon blade to be measured is installed on each clamping fixture, and the dovetail tenon of the dovetail tenon blade to be measured is clamped and positioned by using the clamping fixture; The three-coordinate measurement method is used to measure the dovetail tenon blade to be measured on each clamping fixture one by one, and after measuring the dovetail tenon blade to be measured on the current clamping fixture, a new dovetail tenon blade to be measured is replaced and waits for the next measurement.

2. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 1, characterized in that: The three-coordinate measurement method is used to measure the dovetail tenon blade to be measured on each clamping fixture one by one, specifically: For each clamping fixture, a three-coordinate measurement coordinate system is pre-established; According to the preset measurement sequence, in the three-coordinate measurement coordinate system corresponding to each clamping fixture, a three-coordinate measuring machine is used to perform cyclic measurement on the dovetail tenon blade to be measured on each clamping fixture.

3. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 2, characterized in that: For each clamping fixture, a three-coordinate measurement coordinate system is pre-established, specifically: Select any clamping fixture and establish a three-coordinate measurement rough positioning coordinate system for the clamping fixture; Taking the three-coordinate measurement rough positioning coordinate system of the clamping fixture as a reference and combining the positional relationship between the other clamping fixtures and the clamping fixture, establish the three-coordinate measurement rough positioning coordinate system of the other clamping fixtures; During measurement, the blade digital model coordinate system is aligned with the three-coordinate measurement coarse positioning coordinate system, the theoretical parameters of the measurement points are obtained from the blade digital model, and the three-coordinate measurement coordinate system is established through the coordinate system fitting method.

4. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 2, characterized in that: The preset measurement sequence specifically includes: According to the number of dovetail tenon blades to be measured, the number of measurements and the starting sequence number of the dovetail tenon blades to be measured are set; Select any clamping fixture to start measuring, set the starting number of measurements to 1 and the starting sequence number of the dovetail tenon blade to be measured to 1, after measuring the dovetail tenon blade to be measured on the clamping fixture, add 1 to the measurement number, add 1 to the blade sequence number, and measure the dovetail tenon blade to be measured on the next clamping fixture; The dovetail tenon blades to be measured on each clamping fixture are measured in a cycle in sequence until the number of measurements reaches the measurement times.

5. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 1, characterized in that: The clamping fixture comprises a positioning column (2), a first positioning block (3), a second positioning block (4) and a third positioning block (5); the positioning column (2) is vertically mounted on the upper end surface of the base plate (1); the upper end surface of the positioning column (2) is used to position the bottom surface of the dovetail tenon; the first positioning block (3) is fixed at a position of the upper end surface of the positioning column (2) close to the first side; the second positioning block (4) is connected to a position directly opposite to the first positioning block (3) through a displacement adjustment component (6); the displacement adjustment component (6) can adjust the second positioning block (4) away from or close to the first positioning block (3); the surfaces of the first positioning block (3) and the second positioning block (4) facing each other are used to position the two end surfaces of the dovetail tenon; the third positioning block (5) is fixed at a position of the upper end surface of the positioning column (2) close to the second side; the first side is perpendicular to the second side; the third positioning block (5) is used to position the working surface of the dovetail tenon.

6. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 5, characterized in that: The displacement adjustment component (6) comprises a sliding hole and a sliding block (60) slidably arranged in the sliding hole, the sliding hole is opened through the first side and the third side of the positioning column (2), the first side is opposite to the third side, and the second positioning block (4) is fixed on the sliding block (60).

7. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 6, characterized in that: The displacement adjustment assembly (6) further comprises a backing plate (61), a screw (62) and an elastic member, wherein the backing plate (61) is fixed to a first side of the positioning column (2), a through hole is formed on the backing plate (61), a threaded hole (600) is formed on one end surface of the slider (60) facing the backing plate (61), one end of the screw (62) is movable through the through hole and is threadedly connected to the threaded hole (600), the elastic member is sleeved on the screw (62), one end of the elastic member abuts against one end surface of the slider (60) facing the backing plate (61), and the other end of the elastic member abuts against the backing plate (61).

8. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 7, characterized in that: The elastic member is a spring.

9. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 5, characterized in that: The positioning column (2) is detachably connected to the upper end surface of the base plate (1).

10. The method for measuring an aircraft engine dovetail blade based on digital modeling according to claim 9, characterized in that: The positioning column (2) is detachably connected to the upper end surface of the base plate (1) via a positioning pin (7) and a bolt (8).

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