A quantitative pressurizing device and method for pasting a wind tunnel balance

Abstract

A quantitative pressurization device for pasting a wind tunnel balance belongs to the field of aerospace wind tunnel test technology. The present invention includes a nut, a guide shaft, a strain sensor, a lower crossbeam, an upper crossbeam and a force screw. Two guide shafts are provided, and the axes of the two guide shafts are arranged parallel to each other. The two guide shafts penetrate the upper crossbeam, the strain sensor and the lower crossbeam from top to bottom in sequence, and are located on the guide shafts on the top side of the upper crossbeam and the bottom side of the lower crossbeam. The thread is matched with a nut, and the force screw vertically penetrates the upper crossbeam and cooperates with its thread. The bottom of the force screw is in contact with the top surface of the strain sensor, and a wind tunnel strain balance is clamped between the strain sensor and the lower crossbeam. The present invention can achieve pressurization quantification and standardization and normalization of balance pasting pressurization to solve the problem that the current wind tunnel balance pasting technology does not provide a combination solution of a force nut and a pressure sensor, and the friction between the force nut and the bolt may cause errors.

Description

Technical Field

[0001] The invention relates to a wind tunnel balance pasting quantitative pressurizing device and method, belonging to the technical field of aerospace wind tunnel test. Background Art

[0002] Aerospace vehicle development requires the rapid establishment of a complete aerodynamic database within a short R&D cycle to provide a basis for subsequent performance evaluation, load calculation and structural design. The strain gauge balance is one of the key equipment for wind tunnel force measurement experiments. The accuracy of the balance directly affects the accuracy of wind tunnel test data. The accuracy of the strain gauge balance is mainly determined by the balance design, processing, pasting and calibration. The quality of strain gauge pasting is one of the key factors determining the accuracy of the wind tunnel balance, so the pasting process must be carried out in accordance with a scientific and reasonable pasting process.

[0003] During the pasting process of the wind tunnel strain balance, applying quantitative pressure to the resistance strain gauge on the surface of its measuring element is an important step to ensure that the balance has good performance. At present, the pasting of wind tunnel strain balances mainly relies on the experience of the pasting personnel to estimate the pasting pressure, and it is impossible to accurately apply quantitative pressure. If the pasting pressure is too high, the resistance value after pasting will be abnormal, and if the pressure is too low, there will be bubbles inside the strain gauge or the bonding will be unreliable. If the pressure-applying fixture is not standardized and the pressure is uneven during pressurization, the strain gauge will be unevenly stressed, causing the strain gauge sensitive grid to deform and the resistance value to be abnormal. The existing balance pasting fixture does not have the quantitative pressurization function. The structural form and external dimensions of the fixture are customized according to the structural form and dimensions of a specific balance. The interchangeability of pasting fixtures between different balances is poor, and it is impossible to achieve the universal pasting of the pasting fixture for all rod-type wind tunnel strain balances.

[0004] At present, relevant design methods have also been developed in the quantitative pressurization of strain balance pasting. The existing patent publication number is CN107796593A, which is a universal rod-type wind tunnel strain balance pasting quantitative pressurization system. It adopts an integral frame structure to solve the problem that the pressure value cannot be quantified during the pasting process of the rod-type wind tunnel strain balance. However, it does not provide a combination of the force nut and the pressure sensor, and the friction between the force nut and the bolt may cause errors; and the existing patent publication number is CN112729763A, which is a symmetrical quantitative pressurization device for pasting a wind tunnel balance. It adopts a symmetrical structure and provides the balance with a quantitative pressurization function by calibrating the relationship between the spring compression and the pressure. However, the spring structure is not stable enough, the measurement process is prone to errors, and the service life is short.

[0005] Therefore, it is urgent to propose a novel wind tunnel balance pasting quantitative pressurization device and method to solve the above technical problems. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the friction between the force nut and the bolt will cause errors, and the problem that the spring structure is not stable enough and the measurement process is prone to errors. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0007] The technical solution of the present invention:

[0008] Solution 1: A quantitative pressurizing device for pasting a wind tunnel balance, comprising a nut, a guide shaft, a strain sensor, a lower crossbeam, an upper crossbeam and a force screw. Two guide shafts are provided, and the axes of the two guide shafts are provided parallel to each other. The two guide shafts penetrate the upper crossbeam, the strain sensor and the lower crossbeam in sequence from top to bottom. The upper and lower ends of the guide shaft are threaded with nuts, the force screw is threaded with the upper crossbeam, the bottom of the force screw is against the top surface of the strain sensor, and a wind tunnel strain balance is clamped between the strain sensor and the lower crossbeam.

[0009] Preferably: the strain sensor includes an upper slide, a lower slide, a "bow"-shaped beam and a strain gauge, the guide shaft slides through the left and right sides of the upper slide and the lower slide, the upper slide and the lower slide are fixedly connected by the "bow"-shaped beam, and a strain gauge is arranged on the "bow"-shaped beam.

[0010] Preferably, a cushion block is provided between the strain sensor and the wind tunnel strain balance, and between the lower cross beam and the wind tunnel strain balance.

[0011] Preferably, a rubber sheet is provided between the cushion block and the wind tunnel strain balance.

[0012] Preferably, two "bow"-shaped beams are provided, and the two "bow"-shaped beams are arranged inversely.

[0013] Preferably, eight strain gauges are arranged on the two "bow"-shaped beams, and the eight strain gauges form a Wheatstone bridge.

[0014] Solution 2: A method for quantitatively pressurizing a wind tunnel balance by pasting is implemented based on a device for quantitatively pressurizing a wind tunnel balance as described in Solution 1, and includes the following steps:

[0015] Step 1: Paste the strain gauge onto the "bow" beam;

[0016] Step 2: Calibrate the function K relationship between the voltage signal output of the strain sensor and the applied force through calibration;

[0017] ;

[0018] in, Calibrate the applied force for the strain sensor, m To calibrate the voltage signal output of the strain sensor;

[0019] Step 3: Install the pad on the strain sensor and the lower beam by screws, and stick a layer of rubber on the surface where the pad contacts the wind tunnel strain balance;

[0020] Step 4: Pass the strain sensor through the two guide shafts;

[0021] Step 5: Nuts are threadedly fitted at both ends of each guide shaft, and the nuts clamp the lower crossbeam and the upper crossbeam onto the guide shaft;

[0022] Step 6: Pass the wind tunnel strain balance through the space between the strain sensor and the lower beam, and adjust the position of the wind tunnel strain balance so that the position to be pasted is between the strain sensor and the pad of the lower beam;

[0023] Step 7: Match the force screw with the upper beam thread, tighten the force screw, observe the output of the strain sensor, and stop when the force screw reaches the specified pressure value. At this point, the quantitative pressurizing device for the balance has completed a pasting process.

[0024] The present invention has the following beneficial effects:

[0025] 1. The present invention can realize pressurization quantification, solve the problem that the friction between the force nut and the bolt will cause errors, avoid the situation in the prior art where the spring structure is not stable enough and the measurement process is prone to errors, and can realize the standardization and normalization of balance sticking pressurization;

[0026] 2. The present invention adopts a "bow" type strain sensor as a core component, and calibrates it through the balance calibration technology, so that the accuracy and repeatability of the balance pasting quantitative pressurization device itself meet the requirements of the balance national military standard qualification index;

[0027] 3. The present invention can be applied to balances of different sizes by replacing pads of different sizes to meet the needs of balance beams of different specifications;

[0028] 4. The present invention can avoid the "bow"-shaped strain sensor from twisting when pasting and pressurizing through the guide shaft, changing the previous requirement that the pressure plate needs to be close to the root of the beam to prevent twisting, thereby further adapting to balances of different sizes;

[0029] 5. The present invention has a simple structure and an ingenious design, can be reused, and saves test costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a usage status diagram of a quantitative pressurization device pasted on a wind tunnel balance;

[0031] Figure 2 It is a three-dimensional diagram of a quantitative pressurization device pasted on a wind tunnel balance;

[0032] Figure 3 is a front view of the strain sensor of the present invention;

[0033] Figure 4 is a main-view stereogram of the strain sensor of the present invention;

[0034] Figure 5 is a side-view stereogram of the strain sensor of the present invention;

[0035] Figure 6 is a connection circuit diagram of eight strain gauges of the present invention;

[0036] Figure 7 It is a structural schematic diagram of the cushion block of the present invention.

[0037] In the figure: 1-nut, 2-wind tunnel strain balance, 3-guide shaft, 4-strain sensor, 5-lower beam, 6-upper beam, 7-force screw, 8-pad, 9-rubber, 41-upper slide seat, 42-lower slide seat, 43-"bow" beam, 44-strain gauge. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0039] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection is a non-detachable connection including but not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but not limited to conventional detachable methods such as threaded connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can always be found in the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example: a fixed connection is selected as a welding connection, and a detachable connection is selected as a hinge connection.

[0040] Specific implementation method 1: Combination Figure 1-Figure 7The present embodiment is described. A quantitative pressurizing device for pasting a wind tunnel balance in the present embodiment comprises a nut 1, a guide shaft 3, a strain sensor 4, a lower crossbeam 5, an upper crossbeam 6 and a force screw 7. Two guide shafts 3 are provided, and the axes of the two guide shafts 3 are provided parallel to each other. The two guide shafts 3 pass through the upper crossbeam 6, the strain sensor 4 and the lower crossbeam 5 in sequence from top to bottom. The upper and lower ends of the guide shaft 3 are threadedly fitted with nuts 1. The force screw 7 is threadedly fitted with the upper crossbeam 6. The bottom of the force screw 7 is against the top surface of the strain sensor 4. A wind tunnel strain balance 2 is clamped between the strain sensor 4 and the lower crossbeam 5.

[0041] Pads 8 are provided between the strain sensor 4 and the wind tunnel strain balance 2, and between the lower cross beam 5 and the wind tunnel strain balance 2. Pads 8 of different sizes can be replaced to suit different balances for quantitative pasting and pressurization, which has a wider range of applications.

[0042] A rubber sheet 9 is provided between the cushion block 8 and the wind tunnel strain balance 2 .

[0043] The strain sensor 4 includes an upper slide 41, a lower slide 42, a "bow"-shaped beam 43 and a strain gauge 44. The guide shaft 3 slides through the left and right sides of the upper slide 41 and the lower slide 42. The upper slide 41 and the lower slide 42 are fixedly connected by the "bow"-shaped beam 43. The strain gauge 44 is arranged on the "bow"-shaped beam 43. The "bow"-shaped beam 43 is designed to be a winding "bow" shape, so that the strain sensor 4 is an integrally processed "bow"-shaped strain sensor, which realizes quantitative pasting and pressurization of the wind tunnel balance. The "bow"-shaped beam 43 increases the total length of the measuring beam, thereby increasing the total deformation of the measuring beam when pressure is applied.

[0044] There are two "bow"-shaped beams 43, and the two "bow"-shaped beams 43 are arranged inversely to each other, forming a symmetrical layout and having good stability.

[0045] At least two force applying screws 7 are provided to improve the stability of the applied force.

[0046] The two "bow" beams 43 are provided with eight strain gauges 44, such as Figure 3 As shown, the lateral distance between each pair of adjacent strain gauges 44 is , 8 strain gauges 44 form a Wheatstone bridge, point library.

[0047] The upper slide seat 41, the lower slide seat 42 and the "bow" beam 43 are processed from a piece of integral high-strength steel, that is, they are integrally processed and formed.

[0048] Root strain of the bow beam 43 and overall deformation for:

[0049] ;

[0050] ;

[0051] Wherein: P is the applied pressure, L is the length of the “bow” beam 43, E is the elastic modulus of the steel material selected for the “bow” beam 43, b is the width of the “bow” beam 43, h is the thickness of the “bow” beam 43, I is the moment of inertia of the “bow” beam 43, is the lateral distance between each two adjacent strain gauges 44;

[0052] Specific implementation method 2: Combination Figure 1-Figure 7 This embodiment describes a method for quantitatively pressurizing a wind tunnel balance, which is implemented based on a quantitatively pressurizing device for pasting a wind tunnel balance as described in the first embodiment, and includes the following steps:

[0053] Step 1: Paste the strain gauge 44 onto the “bow” beam 43;

[0054] Step 2: Calibrate the function K relationship between the voltage signal output of the strain sensor 4 and the applied force through calibration;

[0055] ;

[0056] Among them, among them, Calibrate the applied force for the strain sensor, m To calibrate the voltage signal output of the strain sensor 4;

[0057] Step 3: Install the pad 8 on the strain sensor 4 and the lower crossbeam 5 by screws, and stick a layer of rubber 9 on the contact surface between the pad 8 and the wind tunnel strain balance 2;

[0058] Step 4: Pass the strain sensor 4 through the two guide shafts 3;

[0059] Step 5: Nuts 1 are threadedly fitted at both ends of each guide shaft 3, and the nuts 1 clamp the lower crossbeam 5 and the upper crossbeam 6 onto the guide shaft 3;

[0060] Step 6: Pass the wind tunnel strain balance 2 through the strain sensor 4 and the lower cross beam 5, and adjust the position of the wind tunnel strain balance 2 so that the position to be pasted is located between the strain sensor 4 and the pad 8 of the lower cross beam 5;

[0061] Step 7: Thread the force screw 7 into the upper crossbeam 6, tighten the force screw 7, observe the output of the strain sensor 4, and stop when the force screw 7 reaches the specified pressure value. At this point, the quantitative pressurizing device for the balance has completed a pasting process.

[0062] In step 7, the force screw 7 is rotated, the "bow" beam 43 is compressed and deformed, and the strain sensor 4 outputs a voltage. The relationship between the pressure and the output voltage is calibrated by the output voltage, and the quantitative pressurization of the wind tunnel strain balance 2 is achieved during the pasting and pressurization process, as shown in the following formula:

[0063] ;

[0064] in, Apply force to the strain sensor. Output for pasting voltage signal;

[0065] In order to verify the quantitative pressurization device for pasting a wind tunnel balance in this embodiment, a five-component wind tunnel strain balance 2 is quantitatively pasted and pressurized. The design load of the strain sensor 4 is 10kg, the self-loading repeatability is 0.018%, and the loading error is 0.25%;

[0066] The zero drift of wind tunnel strain balance 2 after pasting is no more than 0.2μV / V, and the return to zero is no more than 0.2μV / V. The calibration accuracy of the balance meets the advanced indicators of the national military standard, and the accuracy meets the qualified indicators of the national military standard, that is, the quantitative pressurization device for pasting the balance can ensure the adhesion and calibration results of the five-component balance.

[0067] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A quantitative pressurizing device for pasting a wind tunnel balance, characterized in that: The invention comprises a nut (1), a guide shaft (3), a strain sensor (4), a lower cross beam (5), an upper cross beam (6) and a force screw (7), wherein two guide shafts (3) are provided, and the axes of the two guide shafts (3) are arranged parallel to each other, and the two guide shafts (3) pass through the upper cross beam (6), the strain sensor (4) and the lower cross beam (5) in sequence from top to bottom, and the upper and lower ends of the guide shaft (3) are threadedly matched with the nut (1), the force screw (7) is threadedly matched with the upper cross beam (6), the bottom of the force screw (7) is against the top surface of the strain sensor (4), and a wind tunnel strain balance (2) is clamped between the strain sensor (4) and the lower cross beam (5); The strain sensor (4) comprises an upper slide seat (41), a lower slide seat (42), a "bow"-shaped beam (43) and a strain gauge (44); the guide shaft (3) slides through the left and right sides of the upper slide seat (41) and the lower slide seat (42); the upper slide seat (41) and the lower slide seat (42) are fixedly connected via the "bow"-shaped beam (43); and the strain gauge (44) is provided on the "bow"-shaped beam (43).

2. A wind tunnel balance pasting quantitative pressurizing device according to claim 1, characterized in that: A cushion block (8) is provided between the strain sensor (4) and the wind tunnel strain balance (2), and between the lower cross beam (5) and the wind tunnel strain balance (2).

3. A wind tunnel balance pasting quantitative pressurizing device according to claim 2, characterized in that: A rubber sheet (9) is provided between the cushion block (8) and the wind tunnel strain balance (2).

4. A wind tunnel balance pasting quantitative pressurizing device according to claim 3, characterized in that: The “bow”-shaped beams (43) are provided with two, and the two “bow”-shaped beams (43) are arranged inversely.

5. A wind tunnel balance pasting quantitative pressurizing device according to claim 4, characterized in that: Eight strain gauges (44) are arranged on the two "bow"-shaped beams (43), and the eight strain gauges (44) form a Wheatstone bridge.

6. A method for quantitatively pressurizing a wind tunnel balance, which is realized by relying on a quantitatively pressurizing device for pasting a wind tunnel balance as claimed in claim 5, characterized in that: The following steps are involved: Step 1: Paste the strain gauge (44) onto the "bow" beam (43); Step 2: Calibrate the function K relationship between the voltage signal output of the strain sensor (4) and the applied force through calibration; ； in, Calibrate the applied force for the strain sensor, m For calibrating the voltage signal output of the strain sensor (4); Step 3: Install the pad (8) on the strain sensor (4) and the lower crossbeam (5) by means of screws, and a layer of rubber (9) is pasted on the contact surface between the pad (8) and the wind tunnel strain balance (2); Step 4: Pass the strain gauge sensor (4) through the two guide shafts (3); Step 5: Nuts (1) are threadedly fitted at both the upper and lower ends of each guide shaft (3), and the nuts (1) clamp the lower crossbeam (5) and the upper crossbeam (6) onto the guide shaft (3); Step 6: Pass the wind tunnel strain balance (2) through the strain sensor (4) and the lower cross beam (5), and adjust the position of the wind tunnel strain balance (2) so that the position to be pasted is located between the strain sensor (4) and the pad (8) of the lower cross beam (5); Step 7: Fit the force screw (7) with the thread of the upper crossbeam (6), tighten the force screw (7), observe the output of the strain sensor (4), and stop tightening the force screw (7) when it reaches the specified pressure value.

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